Highly Cited Articles
The following is a list of the most cited articles published from 2018 to 2020, according to Web of Science.
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ZHU Wen-Quan, PAN Yao-Zhong, ZHANG Jin-Shui
Chin J Plant Ecol    2007, 31 (3): 413-424.   DOI: 10.17521/cjpe.2007.0050
Abstract5468)   HTML52)    PDF (585KB)(5102)       Save

Aims Net primary productivity (NPP) is a key component of the terrestrial carbon cycle. Model simulation is commonly used to estimate regional and global NPP given difficulties to directly measure NPP at such spatial scales. A number of NPP models have been developed in recent years as research issues related to food security and biotic response to climatic warming have become more compelling. However, large uncertainties still exist because of the complexity of ecosystems and difficulties in determining some key model parameters.
Methods We developed an estimation model of NPP based on geographic information system (GIS) and remote sensing (RS) technology. The vegetation types and their classification accuracy are simultaneously introduced to the computation of some key vegetation parameters, such as the maximum value of normalized difference vegetation index (NDVI) for different vegetation types. This can remove some noise from the remote sensing data and the statistical errors of vegetation classification. It also provides a basis for the sensitivity analysis of NPP on the classification accuracy. The maximum light use efficiency (LUE) for some typical vegetation types in China is simulated using a modified least squares function based on NOAA/AVHRR remote sensing data and field-observed NPP data. The simulated values of LUE are greater than the value used in the CASA model and less than the values simulated with the BIOME-BGC model. The computation of the water restriction factor is driven with ground meteorological data and remote sensing data, and complex soil parameters are avoided. Results are compared with other studies and models.
Important findings The simulated mean NPP in Chinese terrestrial vegetation from 1989-1993 is 3.12 Pg C (1 Pg=1015 g). The simulated NPP is close to the observed NPP, and the total mean relative error is 4.5% for 690 NPP observation stations distributed in the whole country. This illustrates the utility of the model for the estimation of terrestrial primary production over regional scales.

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Cited: CSCD(319)
Ecological stoichiometry: Searching for unifying principles from individuals to ecosystems
HE Jin-Sheng, HAN Xing-Guo
Chin J Plant Ecol    2010, 34 (1): 2-6.   DOI: 10.3773/j.issn.1005-264x.2010.01.002
Abstract2947)   HTML15)    PDF (316KB)(3811)       Save
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Cited: CSCD(312)
ZENG De-Hui, CHEN Guang-Sheng
Chin J Plant Ecol    2005, 29 (6): 1007-1019.   DOI: 10.17521/cjpe.2005.0120
Abstract4679)   HTML33)    PDF (966KB)(3441)       Save

The biological sciences developed very fast during the 20th century and have become increasingly sophisticated and predictive. Along with this trend, areas of research also have become increasingly specialized and fragmented. However, this fragmentation and specialization risks overlooking the most inherent biological characteristics of living organisms. One can ask if the living organisms on the earth have unified and essential characteristics that can connect the disparate disciplines and levels of biological study from molecular structure of genes to ecosystem dynamics. By exploring this question, a new science, ecological stoichiometry, has been developed over the past two decades. Ecological stoichiometry is a study of the mass balance of multiple chemical elements in living systems; it analyzes the constraints and consequences of these mass balances during ecological interactions. All biological entities on the earth have a specific elemental composition and specific elemental requirements, which influence their interactions with other organisms and their abiotic environment in predictable ways. Ecological stoichiometry has been incorporated successfully into many levels of biology from molecular, cellular, organismal and population to ecosystem and globe. At present, the principles of ecological stoichiometry have been broadly applied to research on population dynamics, trophic dynamics, microbial nutrition, host-pathogen interactions, symbiosis, comparative ecosystem analysis, and consumer-driven nutrient cycling. This paper reviews the concepts, research history, principles, and applications of ecological stoichiometry and points out future research hotspots in this dynamic field of study with an aim to promote this discipline of research in China.

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Cited: CSCD(300)
MENG Ting-Ting, NI Jian, Wang Guo-Hong
Chin J Plant Ecol    2007, 31 (1): 150-165.   DOI: 10.17521/cjpe.2007.0019
Abstract6020)   HTML80)    PDF (682KB)(6153)       Save

Plant traits link environmental factors, individuals and ecosystem structure and functions as plants respond and adapt to the environment. This review introduces worldwide classification schemes of plant functional traits and summarizes research on the relationships between plant functional traits and environmental factors such as climate (e.g., temperature, precipitation and light), geographical variation (e.g., topography, ecological gradients and altitude), nutrients and disturbance (including fire, grazing, invasion and land use), as well as between plant functional traits and ecosystem functions. We synthesize impacts of global change (e.g., climate change) on plant functional traits of individuals and plant communities. Research on plant functional traits is very fruitful, being applicable to research on global change, paleovegetation and paleoclimate reconstruction, environmental monitoring and assessment and vegetation conservation and restoration. However, further studies at large scale and including multi-environmental factors are needed and methods of measuring traits need to be improved. In the future, study of plant functional traits in China should be accelerated in a clear and systematic way.

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Cited: CSCD(258)
PIAO Shi-Long, FANG Jing-Yun, HE Jin-Sheng, XIAO Yu
Chin J Plan Ecolo    2004, 28 (4): 491-498.   DOI: 10.17521/cjpe.2004.0067
Abstract4362)      PDF (274KB)(3236)       Save

Estimating carbon storage in terrestrial ecosystems has been a central focus of research over the past two decades because of its importance to terrestrial carbon cycles and ecosystem processes. As one of the most widespread ecosystem types, China’s grasslands play an important role in global change research. The grasslands in China, which are distributed primarily throughout the temperate regions and on the Tibetan Plateau, were classified into 17 community types. In the present study, a statistical model was established to estimate grassland biomass and its geographical distribution in China based on a grassland inventory data set and remote sensing data (Normalized Difference Vegetation Index) using GIS and RS techniques. We found that there was a significant correlation between aboveground biomass density and the maximum annual NDVI when expressed as a power function (R2=0.71, p<0.001). The aboveground biomass was estimated to be 146.16 TgC (1Tg=1012 g) and belowground biomass was estimated as 898.60 TgC (6.15 times of the above biomass) for a total biomass of 1 044.76 TgC. This value accounts for about 2.1%-3.7% of the world’s grassland biomass. The grassland biomass is distributed primarily in the arid and semiarid regions of Northern China and the Qinghai-Xizang Plateau. The average biomass density of China’s grasslands was 315.24 gC·m-2, smaller than the world average. The aboveground biomass density decreases from southeastern China toward the northwest corresponding with changes in precipitation and temperature. Furthermore, aboveground biomass density reached the lowest levels at 1 350 m elevation and peak levels at 3 750 m above sea level which most likely is related to China’s three-step topographical background. The ratio of total biomass of grassland to forest biomass in China is 1/4, much higher than that of the world, suggesting a greater contribution of grasslands to China’s carbon pool.

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Cited: CSCD(258)
Advances and perspective in research on plant-soil-microbe interactions mediated by root exudates
WU Lin-Kun, LIN Xiang-Min, LIN Wen-Xiong
Chin J Plant Ecol    2014, 38 (3): 298-310.   DOI: 10.3724/SP.J.1258.2014.00027
Abstract4275)   HTML41)    PDF (621KB)(6726)       Save

Root exudates have specialized roles in nutrient cycling and signal transduction between a root system and soil, as well as in plant response to environmental stresses. They are the key regulators in rhizosphere communication, and can modify the biological and physical interactions between roots and soil organisms. Root exudates play important roles in biogeochemical cycle, regulation of rhizospheric ecological processes, and plant growth and development, and so on. Root exudates also serve roles in the plant-plant, plant-microbe, and microbe-microbe interactions. Plant allelopathy, intercropping system, bioremediation, and biological invasion are all the focal subjects in the field of contemporary agricultural ecology. They all involve the complex biological processes in rhizosphere. There are increasing evidences that various positive and negative plant-plant interactions within or among plant populations, such as allelopathy, consecutive monoculture problem, and interspecific facilitation in intercropping system, are all the results of the integrative effect of plant-microbe interactions mediated by root exudates. Recently, with the development of biotechnology, the methods and technologies relating to soil ecological research have achieved a remarkable progress. In particular, the breakthroughs of meta-omics technologies, including environmental metagenomics, metatranscriptomics, metaproteomics, and metabonomics, have largely enriched our knowledge of the soil biological world and the biodiversity and function diversity belowground. Research on plant-soil-microbe interactions mediated by root exudates has important implications for elucidating the functions of rhizosphere microecology and for providing practical guidelines. The concept and components of root exudates as well as the functions are reviewed in this paper. An overview on the root-bacteria, root-fungi, and root-fauna interactions is presented in detail. Methods to study root exudates and microbial communities are reviewed and the aspects needed to be further studied are also suggested.

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Cited: CSCD(220)
N and P stoichiometry of plant and soil in lower subtropical forest successional series in southern China
LIU Xing-Zhao, ZHOU Guo-Yi, ZHANG De-Qiang, LIU Shi-Zhong, CHU Guo-Wei, YAN Jun-Hua
Chin J Plant Ecol    2010, 34 (1): 64-71.   DOI: 10.3773/j.issn.1005-264x.2010.01.010
Abstract2925)   HTML6)    PDF (493KB)(2461)       Save

Aims Nitrogen (N) and phosphorus (P) are two key elements of life and are major limiting nutrients in many ecosystems across the world. The balance of N and P has become the focal point of global change ecology and biogeochemistry, especially as aggravated by atmospheric nitrogen deposition. Although N:P stoichiometry has proved useful in studies of nutrient limitation, biogeochemical cycles, forest succession and degraded land, little is known about it in lower subtropical forest succession. Therefore, our objective is to better understand nutrient controlling factors of plant-soil interaction and reveal interactions of N and P to provide insight and theoretical fundamentals for forest management.

Methods We measured total N and P of organs of dominant species and different soil layers in three forests in Dinghushan Biosphere Reserve, Southern China: pine forest (PF, early successional stage), pine and broad-leaved mixed forest (MF, middle stage) and monsoon evergreen broad-leaved forest (MEBF, advanced stage).

Important findings Soil N content in the 0-10 cm soil layer increased with succession; values in PF, MF and MEBF were 0.440, 0.843 and 1.023 g·kg-1, respectively. The largest value of P content in the same layer was in MF (0.337 g·kg-1); the values in PF and MEBF were 0.190 and 0.283 g·kg-1, respectively. Plant foliage N and P content decreased with succession; the largest values for roots were in MF, and the values in PF equaled those in MEBF. Soil N:P ratio in the 0-10 cm layer significantly increased with succession; 2.3, 2.5 and 3.6, respectively. The N:P ratio of various plant organs also increased with succession, and the value in foliage was close to that in roots; the foliage N:P ratios were 22.7, 25.3 and 29.6, respectively. We discussed the characteristics of N:P ratios in soil and plants of the lower subtropical forest ecosystem, the law of N:P ratios in soil and plants in successional series, and the limiting effect of P on the lower subtropical forest ecosystem.

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Cited: CSCD(203)
YUAN Wen-Ping, ZHOU Guang-Sheng
Chin J Plan Ecolo    2004, 28 (4): 523-529.   DOI: 10.17521/cjpe.2004.0071
Abstract3473)      PDF (307KB)(3172)       Save
Droughts are the world’s costliest natural disasters, causing an estimated $6-$8 billion in global damages annually and affecting more people than any other form of natural disaster. Given the consequences and pervasiveness of droughts, it is important to assess the specialized indices that are used to assess drought severity. The standardized precipitation index (SPI) has several characteristics that are an improvement over previous indices, including its simplicity and temporal flexibility that allow it to examine both short term and long term drought conditions. Computation of the SPI involves fitting a gamma probability density function to a given time series of monthly precipitation totals for a weather station. The resulting parameters are then used to find the probability of a particular precipitation event over a given time scale. This probability is then converted to the standard normal random variable SPI index value. In this article, 1-month SPI are calculated and compared with the Z-index, the most widely used index in China. The results demonstrated that 1-month SPI calculated for 7 observational stations are greatly consistent with Zindex, but that the SPI rarely relates to distributing on precipitation, avoiding some of the irregularities associated with the Z-index. Thus, the SPI is superior to the Z-index in its application. We also investigated drought and flood events from 1951-1995 for Beijing in greater detail. By using the 24-month SPI (SPI24), three well-defined drought and flood events were identified from the data series. In general, the same drought and flood events were observed using the 12-month SPI (SPI12) as the SPI24, although there were some interruptions where the SPI12 values approached zero or became negative for short periods. For 3-month periods (SPI3), the SPI values frequently fell above and below zero. These results highlight the SPI characteristics at different time scales. As the time scale increases from 1 to 24 months, the SPI responds more slowly to short-term precipitation variation, and the cycles of positive (wet conditions) and negative (drought) SPI values become more visible. The possibility of calculating the SPI for different time scales enhances its analysis capacity, since it allows the estimation of different antecedent conditions in the soils. Whereas the shortest scales (1 to 3 months) quantifies superficial soil water, which bears a direct significance for agriculture, the longest accumulation scales (12 to 24 months) indicate the state of subsoil moisture as well as other surface and subsurface water resources. The joint consideration of different SPI scales in the analysis contributed to a satisfactory explanation of risk conditions before each flood event reported. These results indicate that the SPI is an effective index for assessing drought conditions at different time scales and should be adopted for use in China.
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Cited: CSCD(203)
C : N : P stoichiometric characteristics of four forest types’ dominant tree species in China
WANG Jing-Yuan, WANG Shao-Qiang, LI Ren-Lan, YAN Jun-Hua, SHA Li-Qings, HAN Shi-Jie
Chin J Plant Ecol    2011, 35 (6): 587-595.   DOI: 10.3724/SP.J.1258.2011.00587
Abstract2655)   HTML7)    PDF (4148KB)(3031)       Save

Aims The nitrogen and phosphorus characteristics of plants represent plant features and responses to environmental factors. Our objectives are to distinguish leaf and litter C : N : P stoichiometric characteristics, nitrogen and phosphorus resorption of trees, and the relationship between stoichiometric ratio and temperature and precipitation for four typical regions in China.

Methods We studied temperate coniferous, subtropical evergreen broad-leaved, tropical monsoon and tropical plantation forest in the Changbaishan, Dinghushan, Xishuangbanna and Qianyanzhou Ecological Stations, respectively. We analyzed leaf and litter C : N : P, N, P and the relation of N, P nutrition limitation at each station.

Important findings Leaf C : N : P in temperate needle and broad-leaved mixed, subtropical evergreen broad-leaved, tropical rain and subtropical plantation forests were 321 : 13 : 1, 561 : 22 : 1, 442 : 19 : 1 and 728 : 18 : 1, respectively. Litter C : N : P of the four forest types were 552 : 14 : 1, 1 305 : 35 : 1, 723 : 24 : 1, 1 950 : 27 : 1, respectively. The C : N of evergreen coniferous forest is higher than in evergreen broad-leaved and deciduous broad-leaved forests, but C : P has no relationship with forest type. Leaf N : P was highest in evergreen broad-leaved forest and lowest in deciduous broad-leaved forest. Plant N : P has a linear relation with latitude and mean monthly temperature, but neither N or P concentration has such a relationship. Plant at high latitude are easily limited by N, those in low latitude are easily limited by P, but results show that plants limited by N or P don’t have higher N or P resorption. Stoichiometric ratios of leaf and litter are consistent, but environmental factors have different effects on different kinds of plant.

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Cited: CSCD(171)
YANG Yuan-He, PIAO Shi-Long
Chin J Plant Ecol    2006, 30 (1): 1-8.   DOI: 10.17521/cjpe.2006.0001
Abstract5526)   HTML20)    PDF (616KB)(2481)       Save

To advance our understanding of the effects of climate change on grassland ecosystems, we used a time series (1982-1999) data set of the Normalized Difference Vegetation Index (NDVI) together with historical climate data to analyze interannual variations in grassland vegetation cover and explore the relationships between NDVI and climatic factors on the grasslands of the Tibetan Plateau. The NDVI increased significantly by a ratio of 0.41% a-1 and a magnitude of 0.001 0 a-1 during the growing season (p=0.015). An increase in NDVI during the growing season resulted from both the advanced growing season and accelerated vegetation activity. The largest NDVI increase was in the spring with a ratio of 0.92% a-1 and a magnitude of 0.001 4 a-1. The NDVI increase in the summer was a secondary contributor to the NDVI increase during the growing season with a ratio of 0.37% a-1 and a magnitude of 0.001 0 a-1. In the spring, the NDVI increased significantly in the alpine grasslands (alpine meadow and alpine steppe) and temperate steppe (p<0.01;p=0.001; p=0.002). During the summer, a significant NDVI increase was found in alpine meadows (p=0.027). However, the NDVI increase in alpine and temperate steppe was not significant (p=0.106; p=0.087). In the autumn, no significant increase was found in the three grasslands (p=0.585; p=0.461; p=0.143). In the spring, the NDVI increase in three grasslands was corresponded to an increase in temperature. In the summer, the NDVI was related to temperature and sensitive to precipitation in the spring in the alpine grasslands (alpine meadow and alpine steppe). However, no significant statistical relationship was found between NDVI and climatic factors in temperate steppe. Significant lagged correlations between precipitation and NDVI were found for alpine grasslands (alpine meadow, alpine steppe).

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Cited: CSCD(170)
YE Zi-Piao, YU Qiang
Chin J Plant Ecol    2008, 32 (6): 1356-1361.   DOI: 10.3773/j.issn.1005-264x.2008.06.016
Abstract3564)   HTML12)    PDF (870KB)(2914)       Save

Aims Our objective is to compare a new photosynthetic light-response model with the non-rectangular hyperbola, rectangular hyperbola, and Prado-Moraes model in fitting data and obtaining the maximum net photosynthetic rate and the light saturation point.

Methods We measured the light-response of photosynthetic rate of winter wheat (Triticum aestivum) under the same chamber CO2 concentration and different air temperatures in North China Plain using a gas analyzer Li-6400. The measured data were simulated by the new photosynthetic light-response model and the non-rectangular hyperbola, rectangular hyperbola and Prado-Moraes models, respectively.

Important findings The new photosynthetic light-response model shows advantage over the non-rectangular hyperbola, rectangular hyperbola, and Prado-Moraes models in fitting data on the maximum net photosynthetic rate and the light saturation point. The main photosynthetic parameters calculated by the new one were very close to the measured data (R2=0.999 4 and R2=0.998 7). Results showed that the apparent quantum was not an ideal indicator to assess the light use efficiency of plants. We suggest the apparent quantum yield be replaced by the quantum yield at the light compensation point due to the unity of the quantum yield for any C3plantspecies under certain environmental conditions.

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Cited: CSCD(155)
LIU En-Ke, ZHAO Bing-Qiang, LI Xiu-Ying, JIANG Rui-Bo, LI Yan-Ting, HWAT Bing So
Chin J Plant Ecol    2008, 32 (1): 176-182.   DOI: 10.3773/j.issn.1005-264x.2008.01.020
Abstract5253)   HTML22)    PDF (371KB)(4897)       Save

Aims Cropping practices and fertilizer/organic matter application affects the soil microbial growth and activity. In china, only few studies have been conducted on the influence of long-term fertilizer and organic matter with fertilizer application on the soil biological properties. Our objective was to study the changes in soil biological and biochemical characteristics under a long-term (15 years) field experiment involving fertility treatments (inorganic fertilizers and organic matter with fertilizers) and two crop rotation systems.
Methods In 1990, thirteen different treatments were established in the Drab Fluvo-aquic soil in Beijing for the long-term experiment. Six treatments were chosen in this study. Four were in a wheat-maize rotation receiving no fertilizer (CK), mineral fertilizers (NPK), mineral fertilizers plus farmyard manure (NPKM) and mineral fertilizers with maize straw incorporated (NPKS). One was in a wheat-maize/wheat-soybean rotation receiving NPK (NPKF). The other was abandoned arable land (CK0) growing weeds. The amount of chemical fertilizer per year was N 150 kg·hm-2, P2O5 75 kg·hm-2, K2O 45 kg·hm-2, manure 22.5 Mg·hm-2 and maize straw 2.25 Mg·hm-2. Established methods were used to analyze soil enzymes and soil physical and chemical characteristics. Analysis was done using an integrative method combining correlation and component analyses in SPSS.
Important findings The soil organic C (SOC) and total N (STN) content, microbial biomass C (SMB-C) & N (SMB-N), activities of soil invertase, phosphatase and urease, and the ratio of SMB-C/SOC and SMB-N/STN were found higher in long-term (15 years) abandoned arable land than those in cultivated arable land soils. However, the soil metabolic quotient, pH value and bulk density of fallow soil were lower than those in cultivated arable land soils. The soil nutrient concentration, microbial biomass C & N, activities of soil invertase, phosphatase and urease, were higher in treatments with fertilizer application (NPK, NPKM, NPKS and NPKF) compared to no fertilizer application treatment (CK). The above soil parameters were also found higher in wheat-maize/wheat-soybean rotation cropping system compared to continuous wheat-maize cropping system. Among the fertilizer application treatments (NPK, NPKM, NPKS and NPKF), NPKM had relative higher soil nutrient concentration, microbial biomass C & N, and enzyme activities compared to other fertilizer application treatments. However, the soil metabolic quotient, pH value and bulk density of NPKM were lower than them.

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Cited: CSCD(149)
YE Wan-Hui, CAO Hong-Lin, HUANG Zhong-Liang, LIAN Ju-Yu, WANG Zhi-Gao, LI Lin, WEI Shi-Guang, WANG Zhang-Ming
Chin J Plant Ecol    2008, 32 (2): 274-286.   DOI: 10.3773/j.issn.1005-264x.2008.02.005
Abstract3939)   HTML14)    PDF (2702KB)(1683)       Save

Aims Lower subtropical evergreen broadleaved forest in Dinghushan is one of typical vegetations in Southern China. Its vegetation is protected very well. Because of its geographical location, the composition of its flora is transitional between the subtropical and tropical. A 20 hm2 permanent plot of 400 m × 500 m was established in 2005 for long-term monitoring of the biodiversity in the forest.
Methods The plot was established following the field protocol of the 50 hm2 plot in Barro Colorado Island (BCI) in Panama. All free-standing trees with diameter at breast height (DBH) at least one centimeter were mapped and identified to species.
Important findings There are 71 617 individuals, belonging to 210 species, 119 genera and 56 families. Its floristic composition is transitional between the subtropical and tropical. The vertical structure of the forest is clear. There are five layers from the top of the canopy to the ground floor, three tree layers (upper, middle and low), one shrub layer and one herb layer, respectively. Based on important value, Castanopsis chinensis, Schima superba and Engelhardtia roxburghiana are the three most dominant species in the upper layer. There are many shade-tolerant and intermediate light-demanding species, such as Cryptocarya chinensis, Xanthophyllum hainanense, Machilus chinensis in mid-layer. Species in low layer are rich and complex, which composition varies a lot. The species-area curve indicates that there is high diversity in the forest and the number of species is close to BCI. There is high proportion of rare species represented by <20 individuals which account for 52.38% of the total number of species. Among these rare species 45% of them lead to be rare by species characteristics, 20% by the floristic transitional nature of the plot, while the rest by disturbances.Size distribution of all individuals shows an invert J-shape, which indicates that the community is in a stable and normal growth status. Size distributions of the dominant species are classified into four types based on their size-class frequencies, unimodal in the top layer, inverse J-shape in middle layer, close to inverse J-shape in middle and low layer, and L-shape in low and shrub layer. Dominant species in different layers are aggregated by the spatial pattern analysis and the spatial patterns of these species in different layers vary with size-classes. However, spatial patterns of them also show complementary within the same size classes, especially in 10-40 cm DBH. The individuals with DBH>40 cm are randomly distributed.

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Cited: CSCD(137)
YANG Hong-Xiao, ZHANG Jin-Tun, WU Bo, LI Xiao-Song, ZHANG You-Yan
Chin J Plant Ecol    2006, 30 (4): 563-570.   DOI: 10.17521/cjpe.2006.0074
Abstract3274)   HTML3)    PDF (413KB)(1653)       Save

Background and Aims Artemisia ordosica is an important sand fixation plant in north China, whereas few studies were conducted on its population patterns. Population patterns of this species are therefore studied, and the aims are mainly: 1) how spatial scales are related to population patterns, 2) whether plant sizes effect population patterns, and 3) what roles environments play in the process of pattern formation?
Methods Two plots in the size of 50 m×50 m were established in the Mu Us sandy land, and all the A. ordosica plants were recorded and mapped. After that, the data were analyzed with the method of point pattern analysis.
Key results On the scales less than certain critical points, the population is usually characterized by non-random distribution (being clumped or regular), and their spatial association is considerably strong, but may be positive or negative. By contrast, if the scales enlarge beyond these points, the plants will disperse randomly, and their spatial association will loosen greatly. Small individuals are more likely to follow clumped distribution than those big ones. The spatial association between plants will turn from positive to negative if their size differences are enlarged increasingly. Unlike the A. ordosica plants growing in fixed sandy land, those plants in semi-fixed sandy land are easier to follow clumped distribution and associate with each other positively.
Conclusions Population patterns and spatial association of A. ordosica depend on spatial scales, individual sizes and environments, and so do their intra-specific relationships. If A. ordosica plants are transplanted into shifting sandy land for sand control and vegetation restoration, they ought to be arranged in the form of clumped distribution rather than regular distribution.

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Cited: CSCD(129)
ZHU Yan, ZHAO Gu-Feng, ZHANG Li-Wen, SHEN Guo-Chun, MI Xiang-Cheng, REN Hai-Bao, YU Ming-Jian, CHEN Jian-Hua, CHEN Sheng-Wen, FANG Teng, MA Ke-Ping
Chin J Plant Ecol    2008, 32 (2): 262-273.   DOI: 10.3773/j.issn.1005-264x.2008.02.004
Abstract3710)   HTML14)    PDF (2581KB)(1948)       Save

Aims Mainly distributed in China, subtropical evergreen broad-leaved forest is one of important vegetation types in the world. Here we report preliminary results of floristic characteristics, community composition, vertical structure, size class structure, and spatial structure of Gutianshan(GTS) forest plot.
Methods We established a 24-hm2 (600 m×400 m) forest permanent plot from November, 2004 to September, 2005 in mid-subtropical evergreen broad-leaved forest of Gutianshan Nature Reserve, China. Following the standard census procedure of the Centre for Tropical Forest Science (CTFS), all free-standing trees ≥1 cm in diameter at breast height (DBH) in the forest were mapped, tagged and identified to species. We employed software R 2.6.0 to analyze our data.
Important findings The results of floristic characteristics indicates that the tropical elements are more than temperate elements. At family level, the proportion of the pantropic type is the greatest (28.6%), the number of the tropic elements are more than temperate ones (24/13). At genus level,there are 53 tropic genera and 44 temperate ones. As for community composition, there are 159 species, 103 genera and 49 families, 140 700 individuals in total. The evergreen tree species in community are dominant (i.e. 91 species, total relative dominance is 90.6%, importance value is 85.6%, accounts for 85.9% of the total abundance). GTS forest plot is typical mid-subtropical evergreen broad-leaved forest, which displays characteristics of both temperate deciduous broad-leaved forest and tropical rain forest. On the one hand, community composition has obvious dominant species, which is similar to temperate deciduous broad-leaved forest. There are 3 mostly dominant species, Castanopsis eyrei, Schima superba and Pinus massoniana. Large numbers of rare species (59 rare species, equal to or less than one tree per hm2) in the community account for 37.1% species richness, which is similar to tropical rain forest. Vertical structure is composed of canopy layer (63 species), sub-tree layer (70 species), shrub layer (26 species).The structure of DBH size class of all species in the plot generally appears reverse 'J' shape, which indicates successful community regeneration. Spatial distribution of several dominant species, from small to adult tree or old tree, shifts from closer aggregation to looser aggregation, and shows different habitat preference. Finally, we compare the large plot approach with conventional sampling method.

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Cited: CSCD(126)
A review of acclimation of photosynthetic pigment composition in plant leaves to shade environment
SUN Xiao-Ling, XU Yue-Fei, MA Lu-Yi, ZHOU He
Chin J Plant Ecol    2010, 34 (8): 989-999.   DOI: 10.3773/j.issn.1005-264x.2010.08.012
Abstract3253)   HTML15)    PDF (450KB)(3107)       Save

Chlorophylls function in harvesting light energy, funneling the excitation to reaction center and converting sunlight into chemical energy, and carotenoids are responsible for light harvesting and photoprotection. Both are vital for photosynthesis. We summarized the distribution and function of the main photosynthetic pigments and variation of pigment composition and content in sun and shade plants. Sun plants possess larger xanthophyll cycle pool size (violaxanthin + antheraxanthin + zeaxanthin), but de-epoxidation level is lower than that of shade plants. The ratio of lutein to xanthophyll cycle pool size is positively correlated to plant shade tolerance. Light intensity and spectral quality vary between different shade sources. Generally for plant growth, building shade is better than vegetation shade, and deciduous shade exceeds coniferous shade. Variation in light intensity may activate two cycles in plants, xanthophyll cycle and lutein epoxide cycle, for light harvesting or energy dissipation. Some species may alter chlorophyll content and Chl a/b ratio to acclimate to different light intensity, but this character is not related to their shade tolerance. Temporary shade is not necessarily detrimental. Xanthophyll cycle pool size is not only determined by daily photon receipt, but also by the way photon flux is distributed over the daylight hours, because light and temperature are both essential for optimal photosynthetic metabolism. The best photosynthetic performances of plants were obtained with the reinforcement of blue, red and far red wavelengths and with a red: far red ratio closer to that observed in nature. We reviewed internal and external factors affecting photosynthetic pigment content and composition, and determined that during the acclimation to different light environments, plants altered pigment composition and content mainly through adjusting the ratio of reaction center to light harvesting complex and PSI/PSII. We also discussed current research problems and provided insight into future relevant research.

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Cited: CSCD(117)
C:N:P stoichiometry across evergreen broad-leaved forests, evergreen coniferous forests and deciduous broad-leaved forests in the Tiantong region, Zhejiang Province, eastern China
YAN En-Rong, WANG Xi-Hua, GUO Ming, ZHONG Qiang, ZHOU Wu
Chin J Plant Ecol    2010, 34 (1): 48-57.   DOI: 10.3773/j.issn.1005-264x.2010.01.008
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Aims Little is known about constrained ratios of carbon, nitrogen, and phosphorus (C:N:P) in terrestrial ecosystems. Our objective was to examine the C:N:P stoichiometry and its relationship with N and P resorption in evergreen broad-leaved forests (EBLF), evergreen coniferous forests (CF) and deciduous broad-leaved forests (DF) at the regional scale.

Methods The study was conducted in Tiantong National Forest Park (29°52′ N, 121°39′ E), Zhejiang Province, eastern China. To estimate foliar and litter C:N:P ratios and N and P resorption efficiencies, we quantified the C, N and P concentrations in leaf and litterfall in EBLF, CF and DF. We used type II regression slopes (reduced major axis, RMA) to determine whether C:N:P stoichiometry varied across gradients of forest production and nutrients.

Important findings The C:N:P ratios in EBLF, CF and DF were 758:18:1, 678:14:1 and 338:11:1 in fresh leaves and 777:13:1, 691:14:1 and 567:14:1 in litterfall, respectively. The foliar C:N ratio was highest in CF, intermediate in EBLF and lowest in DF, while the foliar C:P and N:P ratios were highest in EBLF, intermediate in CF and lowest in DF. In contrast, the litterfall C:N and C:P ratios were higher in EBLF than in CF and DF, and there were no significant differences of N:P ratio among forests. The type II regression slope for N vs. P in leaves of overall plants was statistically >1, suggesting an increasing investment of N with increasing of P in fresh leaves. In contrast, the slope for N vs. P in litterfall approximated 1. N resorption in EBLF was significantly higher than in CF and in DF, but the highest P resorption was observed in DF. Although foliar N:P ratios indicated that EBLF was P limited, DF was N limited and CF was both N and P limited, the nutrient resorption efficiency did not respond with relatively high N resorption in EBLF and high P resorption in DF. We concluded that the relative higher resorption of N and P before leaf abscission could be an inherent property of plants, but was not a mechanism thought to have evolved to conserve nutrients in environments with limited N or P supply.

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Cited: CSCD(117)
Seasonal variations of leaf nitrogen and phosphorus stoichiometry of three herbaceous species in Hangzhou Bay coastal wetlands, China
WU Tong-Gui, WU Ming, LIU Li, XIAO Jiang-Hua
Chin J Plant Ecol    2010, 34 (1): 23-28.   DOI: 10.3773/j.issn.1005-264x.2010.01.005
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Aims Homeostasis constrains the elemental composition of individual species within narrow bounds no matter the chemical composition of the environment or the resource base. Our objective was to determine the dynamics of leaf stoichiometry during the growth period of plants and the optimum time for stoichiometry study.

Methods We monitored leaf N, P stoichiometry of Scirpus mariqueter, Carex scabrifolia and Phragmites australis, the dominant species in Hangzhou Bay coastal wetlands, at different growth stages from May to October 2007.

Important findings Leaf N, P stoichiometry of the Scirpus, Carex and Phragmites species showed differences: 7.41-17.12, 7.47-13.15 and 6.03-18.09 mg·g-1 for N, 0.34-2.60, 0.41-1.10 and 0.35-2.04 mg·g-1 for P, and 7.19-30.63, 11.58-16.81 and 8.62-21.86 for N:P ratios, respectively. The arithmetic means for the three species were (11.69 ± 2.66), (10.17 ± 1.53) and (11.56 ± 3.19) mg·g-1 for N, (0.93 ± 0.62), (0.74 ± 0.23) and (0.82 ± 0.53) mg·g-1 for P, and 16.83 ± 8.31, 14.53 ± 3.91 and 16.49 ± 5.51 for N:P, respectively, but there was no significant difference of N, P stoichiometry (p > 0.05). It showed high N, P concentrations at the early stage of growth because of small biomass and then decreased greatly with leaf expansion during the fast growth period, increased as leaf growth became stable and decreased again with leaf senescence. Leaf N:P was low at the early stage of growth and then increased, decreased strongly at the fast growth period, and became stable after leaf maturation.

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Cited: CSCD(116)
Stoichiometric characteristics of plants, litter and soils in karst plant communities of Northwest Guangxi
ZENG Zhao-Xia,WANG Ke-Lin,LIU Xiao-Li,ZENG Fu-Ping,SONG Tong-Qing,PENG Wan-Xia,ZHANG Hao,DU Hu
Chin J Plan Ecolo    2015, 39 (7): 682-693.   DOI: 10.17521/cjpe.2015.0065
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Aims The objectives of this study were to characterize the C:N:P stoichiometry of the “plant-litter-soil” continuum and to better understand nutrient cycling and stability mechanisms in karst forest ecosystems in Southwest China. Methods Three representative forest sites were selected for each of the primary and secondary communities (28 years of natural restoration) in Northwest Guangxi, and measurements were made on carbon (C), nitrogen (N), and phosphorus (P) contents in plants, litter and soils. Important findings Compared with other regions, the plants in karst forest ecosystems had relatively lower C content and higher N content, with a lower C:N ratio in consistency with the characteristics of plants. After 28 years of natural recovery, N and P absorption in secondary forests were at a relatively stable state compared with the primary forest communities. The values of N:P ratio varied from a range of 16-19 in the primary forest communities to 17-19 in the secondary forest communities, without apparent difference in the mean vale between the two contrasting community types. Soil organic C, N and P in karst forests occurred primarily in the top 0-10 cm soil layer, at 92.0 mg·g-1 C, 6.35 mg·g-1 N, and 1.5 mg·g-1 P, respectively. In contrast, the nutrient utilization efficiency and nutrient resorption rate were lower in karst forest plants than in other plant types, with karst forest plants exhibiting a relatively rapid nutrient turnover rate. The N resorption rate was lower, and the P resorption higher, in the primary forest communities than in the secondary forest communities, indicating that the higher N deficiency and lower P deficiency of the primary forest communities compared with the secondary forest communities. Determination of the C:N:P stoichiometric characteristics in the plant-litter-soil continuum in this study provides a scientific guidance for restoration of the vulnerable karst ecosystem in Southwest China.
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Cited: CSCD(116)
Ecological adaptation of plants and control of rocky-desertification on karst region of Southwest China
GUO Ke, LIU Chang-Cheng, DONG Ming
Chin J Plant Ecol    2011, 35 (10): 991-999.   DOI: 10.3724/SP.J.1258.2011.00991
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Karst region of Southwest China is ecologically very fragile. It has been suffering from severe rock-desertification and its vegetation has been damaging heavily. The restoration or reconstruction of the vegetation is extremely difficult. In recent years, a lot of pure and application-oriented basic researches have been performed in order to scientifically and technologically support the management of the rock-desertification. In this paper, we summarize habitat characteristics of the karst region and review the progress in ecological researches on plant adaptation, plant population, plant community and ecosystem in the region. In addition, as for current situation in management of the rock-desertification, we propose, particularly from angle of plant ecology, expectations for further researches in the region.

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Cited: CSCD(100)
Review of the roles of plants and soil microorganisms in regulating ecosystem nutrient cycling
JIANG Jing, SONG Ming-Hua
Chin J Plant Ecol    2010, 34 (8): 979-988.   DOI: 10.3773/j.issn.1005-264x.2010.08.011
Abstract2797)   HTML12)    PDF (665KB)(3858)       Save

Above- and below-ground are important components of terrestrial ecosystems. Plants and microorganisms are dependent on each other, and they are important in the linkage between above- and below-ground processes. The relationship between plants and soil microorganisms and the fundamental role played by above- and below-ground feedbacks are important in controlling ecosystem processes and properties. Plant species play a fundamental role in nutrient absorption, nutrient accumulation, nutrient distribution and nutrient return. Soil microorganisms are important in controlling plant nutrient availability and soil quality. Our main objective is to summarize the relationships between plants and microbes, such as facilitation and competition. Plants, as producers, provide nutrients for soil microorganisms via leaf litter and root exudation. Soil microorganisms, as decomposers, break down organic matter and provide nutrients to plants. A wide range of soil microbes form intimate symbiotic associations with plants, and this can stimulate plant productivity by delivering limited nutrients to their host plants. However, both plants and microbes compete for nutrients because plant nutrient uptake and microbial immobilization occur simultaneously. We provide an integrated analysis of effects of plant diversity on soil microbial diversity, as well as direct and indirect effects of soil microbes on plant diversity and productivity. Previously, the mechanisms of plants and microorganisms in regulating ecosystem nutrient cycling have been controversial. Litter chemical composition and diversity should be considered important functional traits that explain the mechanisms. It is clear that interactions between plants and microbes play a fundamental role in maintaining the stability of natural ecosystems. This review elucidates the linkage between aboveground and belowground processes, which have been treated separately in the past.

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Cited: CSCD(99)
Leaf stoichiometry of trees in three forest types in Pearl River Delta, South China
WU Tong-Gui, CHEN Bu-Feng, XIAO Yi-Hua, PAN Yong-Jun, CHEN Yong, XIAO Jiang-Hua
Chin J Plant Ecol    2010, 34 (1): 58-63.   DOI: 10.3773/j.issn.1005-264x.2010.01.009
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Aims Plant or biomass stoichiometry can be used to distinguish biological entities (genes, cells, organisms, etc.) based on element composition. Our objective was to determine the stoichiometry characteristics and examine nutrient limitation in evergreen broad-leaved forest, coniferous and broad-leaved mixed forest and coniferous forest.

Methods We determined C, N, P stoichiometry of leaves of 19 dominant trees of 16 taxa in three forest types at the Pearl River Delta Forest Ecosystem Research Station, Guangdong Province, South China.

Important findings Leaf stoichiometry showed large variations: C ranged from 434 to 537 mg·g-1, N from 6.8 to 23.0 mg·g-1, P from 0.56 to 2.10 mg·g-1, C:N from 21.22 to 70.74, C:P from 227.14 to 844.64 and N:P from 5.26 to 20.91. Leaf N, P, C:N and C:P were linearly correlated (p < 0.01). Leaf C, C:P and N:P (weighted average ± standard deviation: (517.85 ± 35.96), (727.47 ± 231.52) and (15.71 ± 3.76) mg·g-1, respectively) were the highest in coniferous forest, followed by mixed forest (509.47 ± 19.38, 553.01 ± 152.32 and 10.93 ± 1.89, respectively) and evergreen broad-leaved forest (481.59 ± 18.35, 412.19 ± 200.91 and 9.46 ± 4.28, respectively), and a reverse sequence was detected for leaf P content. The sequence for N content was coniferous forest ((12.20 ± 5.65) mg·g-1) > evergreen broad-leaved forest ((11.50 ± 4.24) mg·g-1) > mixed forest ((10.51 ± 5.22) mg·g-1) and for C:N was mixed forest (51.35 ± 13.65) > coniferous forest (47.40 ± 15.85) > evergreen broad-leaved forest (45.59 ± 14.70), and higher nutrient use efficiency was discovered in three forest types. Several evergreen broad-leaved trees and evergreen broad-leaved forest had shortages of N.

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Cited: CSCD(94)
YAN En-Rong, WANG Xi-Hua, ZHOU Wu
Chin J Plant Ecol    2008, 32 (1): 13-22.   DOI: 10.3773/j.issn.1005-264x.2008.01.002
Abstract5053)   HTML4)    PDF (405KB)(1781)       Save

Aims It is well documented that nitrogen (N) and phosphorus (P) are the two main growth-limiting nutrients for plants in many natural environments. Plant N:P ratio has proved useful as an indicator of shifts from N (P) to P (N) limitation because it is easily determined and compared. However, little is known about the plant N:P ratio in evergreen broad-leaved forests (EBLF), particularly the pattern along secondary succession. Therefore, our goal was to examine the relationship between the form of nutrient limitation and secondary successional stage by using the N:P ratio of plant leaves (ratio of N to P concentration) as an indicator.
Methods The research was completed in Tiantong National Forest Park (29°52' N, 121°39' E, 200 m elevation), Zhejiang Province, East China. Leaf N and P concentrations of dominant tree species along a secondary succession gradient of EBLF were quantified to provide canopy N:P ratios for different communities. Leaf N and P concentrations of common plant species in a given community were then determined to emphasize the relationships between differences in the N:P ratios among species at each successional stage.
Important finding Shifts in the N:P ratios of species were consistent along the successional series, although the N:P ratios of different species in a given community varied considerably. At the community level, the lowest N:P ratio (7.38) was found in grassland, which was usually considered a primary stage of EBLF succession. Thereafter, the N:P ratio increased to 19.96 in the shrub stage, declined to an average of 14-16 in the mid-stages of succession, including coniferous forest and coniferous-broadleaved mixed forest, and increased at the end stages of succession (e.g. 18.77 in the Schima superba community and 20.13 in the Castanopsis fargesii community). These results suggest that the productivity of vegetation in the Tiantong region is N-limited in the primary stages of succession, N- and P-limited in the mid-succession stages and probably P-limited in the shrub and mature EBLF stages.

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Cited: CSCD(94)
Spatial patterns of Castanopsis eyrei and Schima superba in mid-subtropical broad- leaved evergreen forest in Gutianshan National Reserve, China
LI Li, CHEN Jian-Hua, REN Hai-Bao, MI Xiang-Cheng, YU Ming-Jian, YANG Bo
Chin J Plant Ecol    2010, 34 (3): 241-252.   DOI: 10.3773/j.issn.1005-264x.2010.03.001
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Aims Many mechanisms of forest patterns have been examined in tropical rain forest; however, there are only a handful of similar studies on subtropical broad-leaved evergreen forest. Our objective is to analyze the main mechanisms of distribution pattern of Castanopsis eyrei and Schima superba in GTS (Gutianshan) forest plot.

Methods Based on a stem map of a 24 hm2 permanent plot in the middle subtropical broad-leaved evergreen forest at Gutianshan National Reserve, we analyzed the distribution pattern of the dominant species C. eyrei and S. superba in saplings, juvenile trees, adult trees, large trees and old trees using spatial point pattern analysis. We also examined spatial associations among different growth stages.

Important findings Castanopsis eyrei and S. superba had a clustered distribution across a range of scales (0-100 m). Saplings, juvenile trees and adult trees tended to be more clumped than big trees. Old trees tended to be somewhat more clumped than big trees. Our results suggested that the two species have obvious habitat preferences at larger scales. For C. eyrei, saplings were significantly positively associated with juvenile trees at scales ≤ 100 m, as were saplings and adult trees, juvenile trees and adult trees, adult trees and big trees. Generally there was no correlation between big trees and old trees at scales ≤ 10 m, whereas their association tended to be positive at larger scales (10-100 m). Generally there were negative or no correlations between other size classes. For S. superba, the saplings were significantly positively associated with juvenile trees at scales ≤ 100 m, as were saplings and adult trees, juvenile trees and adult trees. Generally there were negative or no correlations between juvenile trees and old trees, adult trees and old trees, big trees and old trees, saplings and big trees, juvenile trees and big trees, adult trees and big trees. Generally there was negative correlation between saplings and old trees at scales ≤ 20 m, whereas their association tended to be positively at larger scales (25-100 m). These results suggested that dominant species facilitated coexistence of other species through emptying space for colonization of other species, which is probably attributed to density dependence or the Janzen-Connell effect. Both processes depended on species in intensity and acting time.

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Cited: CSCD(93)
XUE Li, HE Yue-Jun, QU Ming, WU Min, XU Yan
Chin J Plant Ecol    2005, 29 (3): 415-421.   DOI: 10.17521/cjpe.2005.0055
Abstract3015)   HTML4)    PDF (590KB)(1283)       Save

Litter characteristics, such as standing crop, water holding capacity, and proportional water holding capacity and absorption rates, were studied in plantations of Cunninghamia lanceolata, Pinus massoniana, Pinus elliottii, Acacia mangium and Eucalyptus urophylla. The dry litter standing crop of C. lanceolata plantation was the largest (6.5×10 3 kg·hm -2 ) among the five plantations, followed by the P. massoniana and A. mangium plantations (5.5×10 3 kg·hm -2 ), the P. elliottii plantation (4.1×10 3 kg·hm -2 ) and the E. urophylla plantation (4.0×10 3 kg·hm -2 ). The order of total water holding capacity of litter was C. lanceolata plantation (17.9×10 3 kg·hm -2 ) > A. mangium plantation (14.8×10 3 kg·hm -2 ) > E. urophylla plantation (14.0×10 3 kg·hm -2 ) > P. massoniana plantation (10.6×10 3 kg·hm -2 ) > P. elliottii plantation (9.8×10 3 kg·hm -2 ). The proportional water holding capacity as a percentage of the litter dry weight in E. urophylla, C. lanceolata, A. mangium, P. elliottii and P. massoniana plantations were 351%, 274%, 269%, 235% and 191%, respectively. The total water holding capacity and proportional water holding capacity of litter increased logarithmically with increasing time immersed in water. The water absorption rate of litter in E. urophylla plantation was the largest among the five plantations, medium in the C. lanceolata and A. mangium plantations, lower in the P. elliottii plantation, and lowest in the P. massoniana plantation. Water absorption rates of litter in all plantations decreased according to equation Y=a+b·t -1 with increasing time immersed in water.

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Cited: CSCD(91)
Ecological stoichiometry of plant nutrients at different restoration succession stages in typical steppe of Inner Mongolia, China
YIN Xiao-Rui, LIANG Cun-Zhu, WANG Li-Xin, WANG Wei, LIU Zhong-Ling, LIU Xiao-Ping
Chin J Plant Ecol    2010, 34 (1): 39-47.   DOI: 10.3773/j.issn.1005-264x.2010.01.007
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Aims Much research is being done on plant nutrients and stoichiometry. Our purpose was to reveal the effects of grazing on plant nutrients and stoichiometry in a typical steppe of Inner Mongolia of China.

Methods We studied nutrient content of C, N and P and their ratio in soil and leaves of dominant plants in three adjacent sites: fenced since 1983 and 1996 and unfenced. We employed the stoichiometric approach and assessed the effects of grazing on spatio-temporal patterns of nutrient cycling between plants and soil in restoration succession of degenerate steppes.

Important findings Both total soil nutrient content and the ratio of the soil total nitrogen and soil total phosphorus (STN:STP) were lower in overgrazed plant communities compared to fenced plant communities at different levels of restoration. Conversely, the ratio of soil organic carbon and STN (SOC:STN) was higher in overgrazed plant communities. The total organic carbon content (TOC) of most plants was higher in fenced communities and lower in grazed communities and was positively correlated with time since community restoration began. However, the content of total nitrogen (TN) and total phosphorus (TP) in plants was higher in fenced communities than that in grazed communities. Both TN and TP correlated negatively with time since restoration began and positively with the degree of degradation due to overgrazing. TP had a larger range in values compared to TN. The stoichiometry ratios of nitrogen and phosphorus (N:P) and carbon and nitrogen (C:N) in leaves were the lowest in grazed communities and correlated negatively with the degree of degradation. These communities had less total N than total P; however, this pattern was reversed in fenced communities, where sometimes both N and P were limiting. We propose that stoichiometry ratios in dominant plant species can serve as indicators of direction of plant succession in this typical steppe.

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Cited: CSCD(90)
LÁ Chao-Qun, TIAN Han-Qin, HUANG Yao
Chin J Plant Ecol    2007, 31 (2): 205-218.   DOI: 10.17521/cjpe.2007.0025
Abstract3301)   HTML9)    PDF (504KB)(2270)       Save

Human activities have greatly changed the pathway and rate of nitrogen transferred from atmosphere to terrestrial ecosystems worldwide. Anthropogenic nitrogen enrichment, as a result of chronic nitrogen deposition, has caused a wide range of impacts on ecosystem structures and functions. In this paper, we summarize the main effects of anthropogenic nitrogen addition on terrestrial ecosystems as follows:

1) Increased nitrogen input may have influences on plant production and ecosystem carbon storage, and the direction and magnitude of responses are determined by initial nitrogen status of ecosystems (N-limited or N-saturated) and local properties of vegetation and soil;

2) Chronic nitrogen addition can also alter soil nitrogen cycling, decrease the capability of soil to retain N, even lead to soil acidification, depletion of base cation, and affect decomposition of SOC;

3) Both high rate of nitrogen deposition and chronic low nitrogen addition may accelerate losses of N-contained gas, but the magnitude of influences depends on initial status of ecosystem (N-limited or P-limited);

4) N enrichment will affect species richness in terrestrial ecosystems, plant communities' structures and dynamics. It may also contribute to forest expansion into grasslands, alter species composition and diversity of mycorrhizal fungi;

5) Continuous N input and the resulting changes in plant composition and physiological feature may have effects on consumption rate and population dynamics of herbivorous insects, and eventually change ecosystem trophic structure through food chain;

6) Since the influences of N addition, increased concentration of CO2 and O3 on ecosystem properties and processes are interdependent, it is difficult to distinguish each effect.

We also summarized the current status of researches on N deposition in China, and proposed the potential research activities and recommendations.

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Cited: CSCD(88)
LUAN Qing-Shan, SUN Jun, SONG Shu-Qun, SHEN Zhi-Liang, YU Zhi-Ming
Chin J Plant Ecol    2007, 31 (3): 445-450.   DOI: 10.17521/cjpe.2007.0054
Abstract3213)   HTML5)    PDF (333KB)(2856)       Save

Aims The Yangtze River Estuary (YRE) faces eutrophication caused by discharge of industrial and agricultural sewage. This leads to frequent harmful algae blooms involving the rapid proliferation of specific toxic species. The aims of our study are to: 1) apply scientific methods and field experiments to clarify the distributional relationship between phytoplankton species and the environment, and 2) provide data on species and environment informative for further research on estuary ecosystem protection.
Methods An interdisciplinary survey of hydrological, chemical and biological resources was conducted in the YRE on August 28 - September 6, 2004. Phytoplankton cell counts and species identification were performed with an inverted microscope at ×100-×400 magnification after sedimentation for 24 h in 25 ml Utermøhl chambers. Temperature, salinity, pH and dissolved oxygen were measured by a pre-calibrated YSI 6000. Other abiotic environmental data were obtained based on protocols of marine investigations. Canonical correspondence analysis (CCA) was applied to explore the relationship between phytoplankton species and environmental parameters using CANOCO4.0.
Important findings Turbidity and nutrient gradient along the Yangtze River runoff were the most important factors influencing the distribution of phytoplankton species. Transparency, nitrate and silicate were major factors affecting the phytoplankton community structure. The dominant phytoplankton species Proboscia alata f. gracillima preferred low nitrate concentration and clear offshore areas, while Skeletonema costatum preferred high nitrate and more turbid waters. CCA can be a useful tool to understand the spatial distribution of phytoplankton species in marine ecosystems.

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Cited: CSCD(87)
Seasonal variations of leaf C:N:P stoichiometry of six shrubs in desert of China’s Alxa Plateau
NIU De-Cao, LI Qian, JIANG Shi-Gao, CHANG Pei-Jing, FU Hua
Chin J Plant Ecol    2013, 37 (4): 317-325.   DOI: 10.3724/SP.J.1258.2013.00031
Abstract1267)   HTML4)    PDF (294KB)(2479)       Save

Aims Our objective was to explore seasonal variations of leaf C:N:P stoichiometry in plants with the same growth form.
Methods We chose six shrubs in the desert of the Alxa Plateau in north-central China (Zygophyllum xanthoxylum, Nitraria tangutorum, Reaumuria soongorica, Ceratoides lateens, Oxytropis aciphylla and Ammopiptanthus mongolicus) and observed their phenological stages from May to October 2010. Leaf samples were collected during this period, and leaf C, N and P contents and C:N:P stoichiometry were monitored.
Important findings Seasonal dynamics of leaf C, N and P contents and C:N, C:P and N:P mass ratio in the six shrubs were species-specifics, and the variation of leaf C, N and P and C:N, C:P and N:P mass ratios in different species were also dramatically different. Based on variation analysis among different seasons within species, there were less seasonal dynamics in C and N contents and C:N mass ratio than the other three parameters including P contents and C:P and N:P mass ratios. The range of values of coefficient of variation (CV) for C and N contents and N:P mass ratio was 0.60%-10.20%, 6.09%-20.50% and 5.87%-18.78%, respectively. For the other three parameters, the range of CV values for P content was 16.43%-43.43%, and C:P and N:P mass ratios were 8.48%-31.95% and 11.86%-40.73%, respectively. With the comprehensive analysis based on the total variation (resulting from two factors: season and species) for each parameter in these six shrubs, the rank of CV for each parameter was P (28.85%) > C:P (25.02%) > N:P (22.18%) > N (14.22%) > C:N (12.48%) > C (4.62%). Factorial analysis of variation for each parameter, with sampling date (season) and species as independent variables, showed that leaf C and N contents and leaf C:N, C:P and N:P mass ratios were mainly determined by plant species. For leaf P contents, it was the sampling date (season).

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Cited: CSCD(86)
CHEN Guang-Sheng, TIAN Han-Qin
Chin J Plant Ecol    2007, 31 (2): 189-204.   DOI: 10.17521/cjpe.2007.0024
Abstract3758)   HTML11)    PDF (562KB)(2812)       Save

Land use/cover change (LUCC) is one of the most concerned environmental problems by scientists, land managers and policy makers. LUCC can affect energy flow, biogeochemical and hydrological cycling in terrestrial ecosystems through altering land surface and species composition. Ecosystem carbon cycling responds differently to various LUCC types, showing a pattern of CO2 release into the atmosphere when LUCC from a high-biomass forest to low-biomass grassland, cropland or urban area. Previous reports indicated that global terrestrial ecosystem released 2.21 Pg C (1 Pg C=1015 g C) per year induced by LUCC during the 1990s, which explains about 25% of the global C emission per year in the same period; and in the last two centuries, the released C from LUCC accounts for 50% of the C emission from fossil fuel combustion. The LUCC patterns are totally diversified for regions around the world, which cause obviously different C fluxes among them. The reports showed that LUCC in the tropics is a C source, while it is a C sink in the middle and high latitude regions in the northern hemisphere, which possibly explain a large part of the “missing carbon sink" in the terrestrial ecosystems. Currently, modeling is the most popular way to simulate LUCC-induced changes in ecosystem C cycling. The quantitative relationship between LUCC patterns and their related processes and ecosystem carbon cycling remains uncertain. This uncertainty causes great discrepancies in the estimation of terrestrial ecosystem CO2 fluxes from land use/cover changes. In the near future, except for carrying on long-term experiments to determine these quantitative relationships, model development by integrating LUCC with vegetation dynamic model and ecosystem process model will be essential for making an accurate estimation of C fluxes induced by LUCC. Sound land management can greatly increase C storage in the terrestrial ecosystems during LUCC processes. However, the quantification of land management effects is not well-established yet and land management is thus not included in most simulation models of LUCC impacts, which needs more researches in the future.

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Cited: CSCD(86)
LAN Guo-Yu, HU Yue-Hua, CAO Min, ZHU Hua, WANG Hong, ZHOU Shi-Shun, DENG Xiao-Bao, CUI Jing-Yun, HUANG Jian-Guo, LIU Lin-Yun, XU Hai-Long, SONG Jun-Ping, HE You-Cai
Chin J Plant Ecol    2008, 32 (2): 287-298.   DOI: 10.3773/j.issn.1005-264x.2008.02.006
Abstract3789)   HTML17)    PDF (2318KB)(1022)       Save

Aims Tropical seasonal rain forest in Xishuangbanna is one of the most species-rich forest ecosystems in China. This area is also one of the biodiversity hotspots for conservation priorities of the world. For the purpose of monitoring long-term dynamics of tree populations, a 20-hm2 plot was established in a dipterocarp forest in Mengla Nature Reserve in 2007 by Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences and Xishuangbanna Administration of Nature Reserves, in collaboration with Alberta University, Canada and Tunghai University (Taiwan, China).
Methods The construction technology and field protocol followed those applied in the establishment of the 50 hm2 plot in the tropical forest of Barro Colorado Island in Panama, developed by Center for Tropical Forest Science, Smithsonian Tropical Research Institute in 1980. All free-standing trees with diameter at breast height (DBH) ≥ 1 cm were tagged, mapped, measured (girth) and identified to species in the plot. Spatial distribution patterns of four dominant canopy tree species (among different tree size classes) and 12 rare species were analyzed by using a point pattern analysis Ripley's L-function.
Important findings A total of 95 834 free-standing individuals with DBH ≥ 1 cm were recorded in the 20 hm2 plot. Of which, 95 498 individuals were identified to species level. This plot included 468 species belonging to 213 genera and 70 families, except for another 336 individuals that could not be identified yet. The flora of plot was mainly composed of species in tropical families. Shorea wantianshuea that dominates the forest canopy was ranked the second in terms of importance value, although it had the largest basal area. Pittosporopsis kerrii, an understory tree species showed the highest abundance (20 918 individuals). The four canopy species had a large number of juveniles and exhibited size structures with reverse-J shape associated with continuously regenerating populations. Young trees (saplings and poles) revealed a clumped spatial distribution, but adults tended to have a random distribution. Most of the 12 rare tree species in the plot also showed aggregated distribution pattern.

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Responses of plant community biomass to nitrogen and phosphorus additions in an alpine meadow on the Qinghai-Xizang Plateau
YANG Xiao-Xia, REN Fei, ZHOU Hua-Kun, HE Jin-Sheng
Chin J Plant Ecol    2014, 38 (2): 159-166.   DOI: 10.3724/SP.J.1258.2014.00014
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Aims Rising soil temperature under the warming process stimulates microbial activity in soils on the Qinghai- Xizang Plateau. Moreover, the eastern edge of Qinghai-Xizang Plateau has been experiencing distinct atmospheric nitrogen deposition with an increasing trend. All of these have led to an increase in the available nutrients in soils. This study was aimed to determine the responses of carbon fixation in the alpine meadow to nitrogen and phosphorus additions on the Qinghai-Xizang Plateau.
Methods The study was conducted in an alpine meadow ecosystem at the Haibei National Field Research Station of Alpine Grassland Ecosystem, Northwest Institute of Plateau Biology, Chinese Academy of Sciences. Four treatments were set up in 2009, including control, nitrogen addition only (N), phosphorus addition only (P), and combined nitrogen and phosphorus additions (NP). Nutrients were added in June or July each year. The aboveground biomass of functional groups and the above- and belowground biomass of plant communities were measured by harvesting in 2012.
Important findings (1) N and P additions increased the aboveground biomass of grass, and the proportion of grass biomass in the community, but decreased the proportion of forb biomass in the community. Only P addition decreased the aboveground biomass of sedge, and the proportion of sedge biomass in the community. (2) N and P additions increased the aboveground biomass by 24% and 52%, respectively, compared with the control. (3) N addition had no effect on the belowground biomass, whereas P addition slightly increased the belowground biomass. (4) N addition had no effect on the total biomass, whereas P addition significantly increased the total biomass. Therefore, N and P additions could relieve the nutrient limitation and stimulate plant growth. Furthermore, the results suggest that the Qinghai-Xizang Plateau could be more limited by P than N on plant growth.

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HU Hui-Feng, WANG Zhi-Heng, LIU Guo-Hua, FU Bo-Jie
Chin J Plant Ecol    2006, 30 (4): 539-544.   DOI: 10.17521/cjpe.2006.0071
Abstract2953)   HTML11)    PDF (244KB)(2264)       Save

Background and Aims Shrublands is one of the major types of terrestrial ecosystems, which widely distributes from tropical to polar regions. Due to their largely distributional area in China, it is very important for us to exactly estimate their carbon storages and spatial distributions. Answers to the following questions were sought: (a) How much is the vegetation carbon storage of major shrublands in China? (b) How are their spatial distributions in China?
Methods Based on published biomass data in shrublands and 1∶4 000 000 digital vegetation map of China, carbon storage of major shrublands in China was estimated using the method of mean biomass carbon density for different shrublands types.
Key Results The carbon storage of six shrublands in China is 1.68±0.12 Pg C (1 Pg = 1015 g) with an total area of 15 462.64×104 hm2. The average vegetation carbon density is 10.88±0.77 Mg C·hm-2, varying from 5.92 to 17.00 Mg C·hm-2 for different shrubland types. The distribution of shrublands is spatially heterogeneous in the country. Shrublands in three provinces (Yunnan, Guizhou and Sichuan) in Southwest China occupies 23.5% of the total area and contributes to approximately one-third (32.6%) of the total carbon storage of six shrubland types in China due to favorable climeste and soil conditions. The area of six shrubland types in Inner Mongolia is the second largest among all the provinces. However, the vegetation carbon storage in Inner Mongolia shrublands is only 84.81 Tg C (1 Tg = 1012 g), following that of Yunnan, Guizhou, Sichuan, Jiangxi, and Hunan. The probable reason is ascribed to its arid or semiarid climatic conditions. Although shrublands hold about 1.5 times the area of forests in China, the carbon storage of shrublands corresponds 27%-40% of forests because carbon density of shrublands accounts for only one-fifth of forests. Similarly, the proportion of vegetation carbon storage of shrublands to that of grasslands in China varies from 36% to 55% due to the different areas of grasslands used in previous studies.
Conclusions This study draw the following conclusions: (a) As important ecosystem types in China, shrublands hold large vegetation carbon storage, which is main component of China's vegetation carbon storage. (b) Because of different climatic and soil conditions, their distributions are spatially heterogeneous in China and The average vegetation carbon density varies greatly for different shrubland types.

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C, N and P stoichiometric characteristics in leaves of Suaeda salsa during different growth phase in coastal wetlands of China
LI Zheng, HAN Lin, LIU Yu-Hong, AN Shu-Qing, LENG Xin
Chin J Plant Ecol    2012, 36 (10): 1054-1061.   DOI: 10.3724/SP.J.1258.2012.01054
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Aims Suaeda salsa is a typical species in coastal wetlands, and understanding change in its stoichiometric characteristics would help to assess its health status and target conservation efforts. We investigated which nutrient factor restricts its growth and proposed theories for protecting and managing coastal wetland by comparing the C, N and P stoichiometric characteristics of S. salsa in different growth periods.
Methods We collected S. salsa leaves in different growth phases from June to November 2010 in Yancheng coastal wetlands, Jiangsu Province. The C, N and P contents of the leaves were measured. Data were analyzed by correlation analysis between N content and C:N and P content and C:P. N content and P content were also analyzed.
Important findings Leaf C content of S. salsa had significant differences among three different growth phases, with the lowest in the growth phase and the highest in the decline phase. Leaf N content in the decline phase is significantly lower than in the mature and growth phases, and no significant difference of leaf P content was found. C:N and C:P were gradually increasing in the growth period while N:P showed a gradually decreasing trend. Correlation analysis indicated that C:N and C:P were negatively correlated with corresponding N, P content in three different phases. N content was positively linearly correlated with P content, indicating consistent demand of N and P by S. salsa. Furthermore, N is a restrictive factor for S. salsa in coastal wetlands during its growth and development.

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WU Jian-Guo, ZHANG Xiao-Quan, XU De-Ying
Chin J Plan Ecolo    2004, 28 (5): 657-664.   DOI: 10.17521/cjpe.2004.0088
Abstract2696)      PDF (284KB)(1578)       Save

Soil carbon is a large component of the global carbon cycle, and the influence of land-use changes on soil carbon pools can significantly affect atmospheric CO2 concentrations. Labile soil organic carbon (LSC) is the fraction of soil organic matter that is most sensitive to changes in land-use. Over the last several centuries, extensive areas of native vegetation in the Liupan Mountain Forest Zone have been converted to croplands and rangelands and, in last several decades, some of these former croplands and rangelands have returned to forests. The impacts of these land-use changes on soil organic carbon (SOC) are unclear. In order to assess the impacts of land-use change on LSC, we compared the LSC concentrations in adjacent plots of secondary forest (i.e. dominated by Quercus liaotungensis, Populus davidiana, or brushwood), cropland, rangeland, and 13, 18, and 25-year old larch (Larix principis-rupprechtii) plantations that were planted on former croplands and rangelands. All plots were the same elevation, exposure and soil type. The LSC concentrations were determined using a KMnO4 (333 mmol•L-1) oxidation technique. It was found that the mean content of LSC in 0-110 cm deep soil layer was 60% lower under cropland (0.605 gC•kg-1) and 36% lower in rangeland (0.973 gC•kg-1) than under the secondary forest (1.612, 1.68 and 1.325 gC•kg-1 for the brushwood, Populus davidiana and Quercus liaotungensis forests, respectively). LSC was 129% and 29% higher under the plantations (1.127, 1.520 and 1.523 gC•kg-1 for the 13, 18 and 25-year old Larix principis-rupprechtii plantations, respectively) than under the cropland and rangeland respectively. The change of LSC content with soil depth was greater under the secondary forest and plantation than under the cropland or rangeland. The difference of LSC content between secondary forest and rangeland or cropland was greater in the 0-70 cm depth than in the 70-90 cm deep soil layer, whereas differences in LSC content between the plantations and rangeland or cropland was greater in the 0-50 cm than 50-110 cm soil layer. The mean fraction of LSC in the 0-110 cm soil layer was 11% lower under cropland (0.087) and 4% lower under rangeland (0.094) than under the secondary forest (0.098, 0.099 and 0.099 for brushwood, Populus davidiana and Quercus liaotungensis forests, respectively). The mean LSC fraction was 13.3% and 5.3% higher under the plantations (0.103%, 0.093% and 0.101% for the 13, 18 and 25-year old Larix principis-rupprechtii plantations, respectively) than under the cropland and rangeland, respectively. The change in the LSC fraction with soil depth under cropland was greater than for all other land use types. The difference in the LSC fraction between secondary forests and rangeland or cropland was greater in the 0-20 cm and 70-110 cm than the 20-70 cm soil layer, whereas the difference in the LSC fraction between the plantation and rangeland or cropland was greater in the 0-110 cm soil layer. In general, the differences in LSC among the different land use types and changes with depth were greater for the content of LSC than the LSC fraction. Differences in LSC among the different land use types are attributed to differences in the inputs, stabilization and quality of soil organic matter, and the distribution of roots among the different land uses. The results of this study indicate that the LSC content and fraction will decline if natural secondary forest are converted to cropland or rangeland but will increase with afforestation of croplands or rangelands. In addition, the distribution of the content or fraction of LSC within the soil profile will change with changes in land use, but the change in the LSC fraction is smaller than the chaoge of the LSC content.

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ZHANG Wen-Hui, DUAN Bao-Li, ZHOU Jian-Yun, LIU Xiang-Jun
Chin J Plan Ecolo    2004, 28 (4): 483-490.   DOI: 10.17521/cjpe.2004.0066
Abstract2272)      PDF (426KB)(1269)       Save

Quercus variabilis is an important economic tree because it not only provides timber and firewood for local farmers, but also is used to produce cork, tannin extract, and edible fungi for commercial use. It is distributed in 22 provinces in China from sub-tropical to temperate regions and at altitudes that range from 50 to 2 000 m. It also plays an important role in the conservation of water and soil. However, little is known about the physiological tolerance mechanisms of drought stress. In order to discriminate among the drought-tolerant characteristics of different Q. variabilis provenances, we conducted a drought stress experiment using potted 3-year old seedlings of four provenances from different regions. Changes in superoxide dismutas activity (SOD), catalase activity (CAT), malondial dehyde content (MDA), electrolyte leakage rate, osmotic potential at saturation (ψπsat), osmotic potential at turgor loss point (Wπtlp), water saturation deficit at turgor loss point (WSDtlp), and modulus of elasticity (εmax) of leaves were measured and analysed as soil drought conditions developed. Under similar conditions of soil drought stress, provenance 4 (from Huanglong Mt. in the loess plateau) and provenance 3 (from the north slope of Qinling Mt.) revealed more antioxidant ability than provenance 2 (from Funiu Mt.) and provenance 1 (from the north slope of Bashan Mt.). During the development of soil drought stress, the MDA content and electrolyte leakage rate were enhanced to different extents in the four provenances; the greatest change was provenance 1 and the lowest change in provenance 4. The activities of SOD and CAT increased at the beginning of stress conditions but decreased at the end of the drought stress period. All provenances had the ability to maintain turgor and osmotic adjustment throughout the experiment but distinct differences among provenances were apparent: provenance 4 and provenance 3 had greater turgor maintenance and osmotic adjustment while provenance 1 performed the worst. Using Fuzzy synthetic evaluation of the parameters of water relations and the activities of two cell defense enzymes to water stress in leaves, the level of drought-tolerance among the four provenances decreased in the following order: provenance 4> provenance 3> provenance 2> provenance 1. Among the four provenances, provenance 4 was significantly different from the provenance 2 and provenance 1 (p<0.05). Differences in the drought tolerant characteristics of the four provinces resulted from long-term evolution and adaptation to their particular environmental conditions and are most likely genetically controlled. Therefore, these characteristics should be used for selecting and identifying drought tolerant provenances for use in forest management and restoration of Q. variabilis in arid regions.

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Allocation of nonstructural carbohydrates for three temperate tree species in Northeast China
YU Li-Min, WANG Chuan-Kuan, WANG Xing-Chang
Chin J Plant Ecol    2011, 35 (12): 1245-1255.   DOI: 10.3724/SP.J.1258.2011.01245
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Aims The content and allocation of nonstructural carbohydrates (NSC) in trees reflect whole-tree carbon balance regimes, and are crucial to determine growth / survivorship trade-off of trees and model tree carbon balance between uptake and investments in structure or loss. Our objective was to examine the concentration and allocation patterns of NSC for three temperate tree species, i.e., Korean pine (Pinus koraiensis), Dahurian larch (Larix gmelinii) and Mongolian oak (Quercus mongolica).
Methods During the mid-growing season (July of 2010), all biomass tissues, including foliage, branch, stem and root, were randomly sampled from three dominant trees for each species. The stem samples were taken from mid-canopy and breast height, and divided into sapwood and heartwood, while the root samples were divided into fine (diameter < 2 mm), medium (2-5 mm) and coarse roots (>5 mm). All samples were dried, ground, and analyzed for NSC concentrations (including soluble sugar and starch) with a modified phenol-sulfuric acid method.
Important findings The concentrations of NSC and its component differed significantly among species and tissues. Concentration ranges were 0.65-8.45, 1.96-5.95 and 3.00-13.90 g·100 g-1 DM for soluble sugar, starch, and NSC, respectively. On average, the contents of NSC and its components followed the order of: larch > oak > pine. Concentrations in the foliage and roots were higher than those in other tissues. Within the stems, the longitudinal variations in the concentrations of NSC and its components were insignificant, whereas the differences between sapwood and heartwood varied with species and NSC components. There was no significant difference in soluble sugar concentration between sapwood and heartwood, but significant differences in starch and total NSC concentration. The concentrations of NSC and its components varied insignificantly with root diameters for larch and pine, but significantly for oak. Oak invested more soluble sugar to aboveground growth, whereas the two conifers did more to roots. Nevertheless, starch was mainly reserved in stems, and the intra-tree allocation pattern of starch exhibited an opposite trend to soluble sugar, leading the total NSC to be relatively balanced between roots and branches. In the stems, heartwood was the major reserve of NSC and starch, while sapwood was the major reserve of soluble sugar for the two conifers. In the roots, coarse root was the dominant reserves of NSC and its components. We concluded that the inter- and intra-specific variations in the NSC and its components in this study reflect differences in growth strategies and within-tree carbon source / sink strength for the three temperate tree species.

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Canopy leaf N and P stoichiometry in grassland communities of Qinghai-Tibetan Plateau, China
YANG Kuo, HUANG Jian-Hui, DONG Dan, MA Wen-Hong, HE Jin-Sheng
Chin J Plant Ecol    2010, 34 (1): 17-22.   DOI: 10.3773/j.issn.1005-264x.2010.01.004
Abstract2735)   HTML6)    PDF (315KB)(2003)       Save

Aims Leaf N and P stoichiometry has been widely studied at the species level in both aquatic and terrestrial ecosystems, however, it lacks research at the community level. Since the ecological stoichiometric characteristics could play important roles in connecting different levels of ecological studies and former studies mainly focused on the individual level, in this study, we try to figure out the pattern of foliar N and P at the community level of grassland ecosystems in Qinghai-Tibetan Plateau. Additionally, we also try to find out the relationships between community level leaf N, P and site climate factors.

Methods Leaf samples were collected from 47 research sites in Qinghai-Tibetan Plateau at the end of the growing season yearly from 2006 to 2008. We measured the leaf N concentrations by using an elemental analyzer and the leaf P concentration based on a molybdate/stannous chloride method. Climate data of annual mean temperature and annual mean precipitation (65 national standard stations) between 2006 and 2008 were used to interpolate into gridded data with a resolution of 1 km × 1 km through the tchebycheffian spline function.

Important findings Leaf N, P concentrations and N:P ratios at the community level over the southern part of Qinghai-Tibetan Plateau were 23.2 mg·g-1, 1.7 mg·g-1 and 13.5, respectively. Significant inter-annual differences were presented in leaf N, P concentrations and N:P ratios. Mean annual temperature was strongly correlated with leaf N, P and N:P ratios. Besides, the correlations between climate factors and leaf N, P, N:P ratios were generally consistent with the previous results found at the global scale. Our results suggest that the high variation in leaf P concentration and its strong correlation with environmental factors reveal that, to some extent, stoichiometric traits at the community level are adaptive to local environmental conditions.

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ZHANG Feng, ZHOU Guang-Sheng, WANG Yu-Hui
Chin J Plant Ecol    2008, 32 (4): 786-797.   DOI: 10.3773/j.issn.1005-264x.2008.04.007
Abstract3638)   HTML7)    PDF (429KB)(2563)       Save

Aims Vegetation net primary productivity (NPP) and its responses to global change have been focuses of global change research. Accurately estimating the spatial patterns and temporal dynamics of net primary productivity (NPP) of terrestrial ecosystems is of great interest to human society and is necessary for understanding the carbon cycle of the terrestrial biosphere. But only a few evidences in various biomes are available on the performance of global models of terrestrial net primary productivity (NPP) at ecosystem level.

Methods Vegetation net primary productivity (NPP) derived from a carbon model (Carnegie-Ames- Stanford Approach, CASA) and its inter-annual change at ecosystem level in Inner Mongolian typical steppe, China, are investigated in this study using 1982~2002 time series data sets of normalized difference vegetation index (NDVI) at 8 km spatial resolution and paired ground-based information on vegetation, climate, soil, and solar radiation, after CASA model is validated by the aboveground biomass of 13 years’ continuous observation.

Important Findings Results show that 21-year averaged annual NPP is 290.23 g C·m-2·a-1, ranging between 145.80 g C·m-2·a-1 and 502.84 g C·m-2·a-1. From 1982 to 2002, annual NPP shows a slightly increasing trend, while from 1982 to 1999 a significant increase (p<0.01) is observed, and the increasedNPP is mainly due to the increases of the amplitude of the NPP annual cycle. Annual precipitation significantly affects the variation of NPP, and there is no significant positive correlation between NPP and annual mean temperature.

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Controlling action of soil organic matter on soil moisture retention and its availability
LIU Xiao-Dong, QIAO Yu-Na, ZHOU Guo-Yi
Chin J Plant Ecol    2011, 35 (12): 1209-1218.   DOI: 10.3724/SP.J.1258.2011.01209
Abstract2383)   HTML4)    PDF (504KB)(2553)       Save

Aims Assessment of the ecological benefits of forest in soil water retention based on conventionally monitored factors and exploration of the relation between forest carbon-sink function and hydrological benefits has special meaning in Millennium Ecosystem Assessment. Our objectives were to 1) characterize the spatial and temporal variations of soil moisture in three subtropical forests and 2) determine the controlling action of soil organic matter on soil moisture retention during vegetation succession.
Methods Standard plots were established in Pinus massonnianaconiferous forest (PF), mixedPinus massonniana-broad-leaved forest (PBF) and monsoon evergreen broad-leaved forest (MBF). We measured soil water content every 10 days from 2002 to 2008 using neutron probes and analyzed soil organic matter content in the laboratory by the potassium dichromate oxidation method.
Important findings With natural succession from planted PF to climax MBF, soil water content (0-30 cm soil layer) increased significantly; soil water content was highest in MBF and lowest in PBF. The distribution patterns of soil moisture in the three forests were different: the soil moisture of MBF decreased with soil depth, was more homogeneous in the soil profile in PBF and was lower at the surface than in deeper layers in PF. The soil water characteristic curves showed that under the same matrix suction the magnitude of soil water content (0-40 cm soil layer) was: MBF > PBF > PF; the soil of MBF was the most retentive. Further analysis indicated that soil porosity had the greatest impact on soil moisture, followed by saturated soil water content and soil organic matter content, while soil bulk density had a minimal impact. In the process of natural succession, soil moisture was significantly correlated with the soil organic matter content ( p = 0.014), as the soil organic matter could affect soil moisture holding (p = 0.030). Accordingly, we recommend soil organic matter as an effective and integrated index for appraising forest ecosystem services.

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