Table of Content
Volume 30 Issue 2
30 March 2006

Research Articles
STUDY ON ECOSYSTEM SERVICES: PROGRESS, LIMITATION AND BASIC PARADIGM
XIE Gao-Di, XIAO Yu, LU Chun-Xia
Chin J Plan Ecolo. 2006, 30 (2):  191-199.  doi:10.17521/cjpe.2006.0028
Abstract ( 3398 )   PDF (706KB) ( 1711 )
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The concept of ecosystem services was first used in 1960s in abroad and the terminology of “ecosystem services” appeared in 1981. Three classificat ions of ecosystem services included function classification, structure classification and description classification, in which function classification has been used widely. The relationship between ecosystem services and biodiversity was examined to understand the mechanism of formation and variation in ecosystem services. At present, many case studies have been conducted to obtain the economic values of ecosystem services at local, river basin, regional and national levels with three kinds of methods: economic method, emergy method and benefit transfer. In China, the concept of ecosystem services was introduced in 1990s and, since then, there have been many studies about ecosystem services which involves the in troduction of abroad studies, forming and accumulating process of ecosystem services and case studies. Because of limitations on the studies of ecosystem services, including the reliability of the evaluation results, confusion of ecological capital and ecosystem services, uncertainty of the quantity of ecosystem services, uncertainty of the monetary values of ecosystem services, and complexity of ecosystem functions and services. A new paradigm of ecosystem services should be set to strictly distinguish the ecosystem services from ecological capital, to evaluate the ecosystem services on the basis of ecological monitoring and ecological models, and to divide the region into different units in evaluation of regional ecosystem services . The researches on ecosystem services should pay more attention in the complex relationships between ecosystem services, structure and processes, the response and feedback of ecosystem services to human activities, the impacts of changes in ecosystem services on human well_being, the impacts of policies and institutions on ecosystem services, and the monetary values of ecosystem services from different kinds of ecosystems.

CARBON SEQUESTRATION: MANNERS SUITABLE FOR CARBON TRADE IN CHINA AND FUNCTION OF TERRESTRIAL VEGETATION
LI Xin-Yu, TANG Hai-Ping
Chin J Plan Ecolo. 2006, 30 (2):  200-209.  doi:10.17521/cjpe.2006.0029
Abstract ( 2420 )   PDF (840KB) ( 1094 )
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The Kyoto Protocol provides three mechanisms that would allow transfers or crediting of emission reductions achieved in other countries. Reductions of greenhouse gases (GHGs) emission are attained at the lowest possible cost, with equal benefit to the environment. Developing countries can benefit from the investment of funds available for project development, gain new emission_reduction technology, and earn a profit by selling their emission reductions credit. The core issue of carbon trade is whether there is enough carbon sequestration credit for trading after offsetting the CO2 emission. This paper compared and synthe sized most of the potential and existing manners of CO2 emission reduction and carbon sequestration in current aspects of techniques, cost_effective, effect on th e carbon sink of ecosystem and other aspects. Large_scale biogas cogeneration or co_firing in coal power stations with cost_effective and energy_saving measures can reach better emission_reduction benefit and carbon sequestration efficiency . The process of carbon sequestration in terrestrial ecosystem, which can remove carbon from the atmosphere and sequester it in biomass and soil, is most safety and efficiency, with no expense of CO2 separation and purification as well. Not only forest ecosystem possesses one of the most reliable carbon sequestration processes, but also the large_scale grassland soil and farmland soil do have. As a result, some projects related to CO2 emission reduction and carbon sequestration, such as establishing natural forest and grassland reserves, planting high_yield woodland, setting up artificial pasture with high productivity and stable yield, adopting way of eco_agriculture, remaining more straw in the field, making the best use of marginal land to grow bio_energy，promoting the exploitation of bio_energy and other projects, which are cost_efficient and suitable for China, should be conducted to enforce and increase carbon sequestration of terrestrial ecosystem in accordance with their respective characters.

ADAPTIVE SIGNIFICANCE OF HERKOGAMY AND FLORAL BEHAVIOUR
RUAN Cheng-Jiang, JIANG Guo-Bin
Chin J Plan Ecolo. 2006, 30 (2):  210-220.  doi:10.17521/cjpe.2006.0030
Abstract ( 3209 )   PDF (849KB) ( 992 )
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With their critical role in plant pollination and mating system, the adaptive significance of herkogamy and floral behavior has well been studied in plant reproductive biology and evolutionary ecology. Here we review recent progress in this field, especially discuss the adaptive significance of movement approach herkogamy in monadelphous tube in Malvaceae, which involves decrease of herkogamy resulting from the curvature of stigma lobe. Herkogamy, the spatial separation of pollen presentation and pollen receipt with in flowers, appears in many animal_pollinated plants. Due to its positive correlation with outcrossing rates in some species with mixed_mating systems, herkogam y has been previously considered as a mechanism to prevent self_pollination. However, increasing evidences suggest that herkogamy may act as a mechanism to reduce interference between the reproductive functions of female and male organs. Functional studies of heterostylous species indicate that sex_organ reciprocity serves to promote cross_pollen transfer between floral morphs and that enantiostyly and stigma_height dimorphism function in a similar manner.  Intra_floral sex interference often contains physical interference and pollen clogging. The former involves stamens obstructing the deposition of outcrossing pollen on stigmas and pistil reducing pollen export (an experimental evidence is given recently). The latter involves pollen discounting and ovule discounting, an d its experimental evidence has been largely reported in many plants.  The behaviors of different floral parts (style, stamen, pollen, corolla, etc.) may have adaptive significance, including reducing intrafloral male_female interf erence, avoiding self_pollination, promoting delayed autonomous selfing, and responding to the harsh environment. Movement approach of herkogamy in monadelphous tube in Malvaceae, making the herkogamy decrease by the curvature of stigma lobe, is unusual and intriguing, and its adaptive significance may involves promoting outcrossing, facilitating delayed selfing if outcrossing fails, and interferences between two sexual organs.  We believe that the trends studying on the their functions are transiting from the research stage mainly depending on the description to comprehensive resear ch phase combining modern experimental technology (e.g. the molecular markers of SSR, SNP, AFLP) and advanced apparatus multi_seasons with traditional method , and with the development of the capacity of field experiments and control conditions，transiting from traditional and classical observations to combining floral manipulation in the field experiments.

WORLD BIODIESEL UTILIZATION AND DEVELOPMENT STRATEGIES IN CHINA
JIA Hu-Sen, XU Yi-Nong
Chin J Plan Ecolo. 2006, 30 (2):  221-230.  doi:10.17521/cjpe.2006.0031
Abstract ( 1730 )   PDF (865KB) ( 719 )
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The stocks of fossil fuels, currently the major energy source driving the global socioeconomy, is being heavily depleted due to increasing anthropogeni cactivities worldwide, and its burning contributes to global climate warming and air pollution. In contrast, biodiesel is an alternative non_toxic, biodegradable, and renewable alternative energy source. This paper discusses the essence, properties and the development of biodiesel fuels, mainly in European countries; discusses the international supply and demand of soybean and rapeseed, the main biodiesel feedstock; and analyzes the production and consumption of edible plant oils in China and its balance as it is affected by international biodiesel development. Considering that domestic foodstuffs and plant oil production currently are insufficient to feed the 1.3 billion people in China due to limited agricultural lands, ultimately ways are needed to grow biodiesel feedstock on unproductive agricultural lands, such as saline_alkaline lands, poor soil, desertified soils, and plough_withdrawn land.

THREE TEMPERATURE (3T) MODEL——A METHOD TO ESTIMATE EVAPOTRANSPIRATION AND EVALUATE
QIU Guo-Yu, WANG Shuai, WU Xiao
Chin J Plan Ecolo. 2006, 30 (2):  231-238.  doi:10.17521/cjpe.2006.0032
Abstract ( 2677 )   PDF (643KB) ( 846 )
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The “Three temperatures (3T) model” is a recently proposed method to estimate evapotranspiration and evaluate environmental quality. Because the key components for this model are three temperature variables, it is referred to as the “3T model”. This study discusses the procedures used to estimate evaporation , and model is verified based on a theoretical analysis and experimental data. By introducing a reference dry soil (a soil without evaporation), soil evaporation (E) can be calculated by:LE=Rn-G-(Rnd-Gd)(Ts-Ta/Tsd-Ta where L is latent heat of vaporization, Rn and Rnd are the net radiations of drying and dry soil, respectively. G and Gd are soil heat fluxes in drying soil and dry soil, respectively. Ts and Tsd are the surface temperatures of drying soil and dry soil, respectively. Ta is the air temperature. Results of the experimental work indicated that the energy fluxes over drying and dry soil were significantly different. Soil heat flux and net radiation on the dry soil are smaller than that on the drying soil, whereas the heat flux of the dry soil is higher than that of the drying soil. Typically, the dry soil surface temperature was higher than that of the drying soil surface temperature and the drying soil surface temperature was higher than the air temperature. Results of a field experiment showed that the measured E (using of a weighing lysimeter) and the calculated E using the 3T model agreed with each other and the mean absolute error (MAE) between them was 0.17 mm•d-1 with a regression coefficient of r2=0.88. Furthermore, by using the temperature measured by infrared thermometers , the MAE between measured and estimated evaporation was 0.15 mm•d -1 with a regression coefficient of r2=0.94. These results showed that evaporation as estimate d by 3T model is accurate. The main advantage of the 3T model is that only a few parameters (temperature, net radiation and soil heat flux) are required. Soil surface resistance, aerodynamic resistance, and other empirical parameters are no t necessary.

LAND COVER DYNAMICS OF DIFFERENT TOPOGRAPHIC CONDITIONS IN BEIJING
WU Xiao-Pu, TANG Zhi-Yao, CUI Hai-Ting, FANG Jing-Yun
Chin J Plan Ecolo. 2006, 30 (2):  239-251.  doi:10.17521/cjpe.2006.0033
Abstract ( 2500 )   PDF (1705KB) ( 1059 )
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Topographic conditions play an important role in controlling land cover dynamic processes. In this study, remotely sensed data and geographic information system were applied to analyze the changes in land cover along topographic gradients from 1978 to 2001 in Beijing, a rapidly urbanized mega city in China. The study was based on five periods of land cover maps derived from remotely sensed data, Landsat MSS for 1978, Landsat TM for 1984, 1992, 1996 and 2001, and digital elevation model (DEM) derived from a 1: 250 000 topographic map. The entire area was divided into 10 land cover types: conifer forest, broadleaf forest, mixed forest, shrub, brushwood, meadow, farmland, built_up, water body and bare land. The results are summarized below. 1) Shrub, forest, farmland and built_up consist of the main land cover types of the Beijing area. The most significant land cover change from 1978 to 2001 was a decrease in farmland and an expansion of built_up areas. Farmland decreased fro m 6 354 to 3 813 km2 over the 23 years, while built_up areas increased from 421 to 2 642 km2. Forest cover increased from 17.2% to 24.7% of the total area. The conversion matrix analysis indicated that transformation of farmland to built_up area was the most significant process and afforestation was the primary cause of replacement of shrub to forest. 2) Topographic conditions are of great importance to the distribution of land cover types and the process of land cover changes. Elevation has a strong impact on the distribution of land cover types. The area below 100 m mostly consisted of farmland and built_up areas, and the area above 100 m is mainly covered by shru b and forest. Shrub has a maximum frequency in elevations between 100 and 1 000 m, while forests were dominant in areas above 800 m. According to the analysis of land cover changes in different elevation ranges, the greatest change was below 100 m due to urbanization. The main land cover change process that occurred ab ove 100 m was transformation from shrub to forest. This result was constant with the vertical change of natural vegetation distribution in Beijing.  3) Slope has a large influence on the distribution of land cover types. Farmland and built_up areas are distributed primarily in flat areas, while shrub and forest occupy steeper lands as compared with other land cover types. Forest frequency increased with increasing slope. Land cover change processes differed with slope gradients. In the plain area, land cover change occurred as the result of urbanization. With increasing slope gradients, afforestation, which converted shrub to forest, was the primary land cover change process.

IDENTIFICATION OF THE SPECTRAL CHARACTERISTICS OF SALTMARSH VEGETATION USING INDIRECT ORDINATION: A CASE STUDY FROM CHONGMING DONGTAN, SHANGHAI
GAO Zhan-Guo, ZHANG Li-Quan
Chin J Plan Ecolo. 2006, 30 (2):  252-260.  doi:10.17521/cjpe.2006.0034
Abstract ( 2509 )   PDF (619KB) ( 1180 )
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Remote sensing is a major source of spatial information of the attributes of the earth's surface, and remote sensing technology has become a primary tool for vegetation classification at large scales. The relationship between vegetation and their spectral characteristics is key for interpreting remote sensing images. This study related characteristics of saltmarsh vegetation at the intertidal zone of Chongming Dongtan Nature Reserve, Shanghai, to patterns of their spectral reflectance. Paired measurements of saltmarsh community and spectral cha racteristics were carried out along three transects covering the major variations in vegetation and environment within the study area. The spectral characteristics were measured by a ground FieldSpec Pro JR spectroradiometer and the spectral data were converted to simulate the 10 bands of Compact Airborne Spectrogr aphic Imager (CASI) bandset. The spectral data sets were then ordinated using Pr incipal Component Analysis (PCA), an indirect ordination technique. The eigenvalue of the first PCA axis was 19.9, which represented 98.5% of the variation in the spectral data. A sequence of bare mudflat, Scirpus mariqueter community, Spartina alterniflora community and Phragmites australis community changed along the first ordination axis showed a strong correspondence with variation in the bands six to ten, i.e. the simulated CASI wavebands covering the 736 to 870 nm wavel engths. A significant relationship between the first axis PCA scores for the spectral data of quadrats and their percentage community cover and height also was identified. The second axis accounted for only 1.4% of the variation in the spectral data and it proved impossible to demonstrate any close link between any specific plant community type and a distinct set of spectral characteristics because of its low representation of the variation in the spectral data. Our study has demonstrated that the variation in the spectral data of saltmarsh vegetation at Chongming Dongtan Nature Reserve can be identified using the indirect ordination technique of PCA and then applying correlation and regression analyses to explain the relationships between the variation in the spectral data with the vegetation and ecological data. Our results indicate that PCA is of value for identifying relationships between community types and the spectral data of CASI bandsets for saltmarsh vegetation. This could provide an effective and practical approach for classification of saltmarsh vegetation at large scales and for monitoring spatio_temporally dynamic patterns of saltmarshes at Chongming Dong tan Nature Reserve. Further work is required in order to test these conclusions. The method has been evaluated for a single season with a limited sample of salt marsh plant communities, and the application of PCA and spectral data of CASI bandsets to other saltmarsh vegetation as well as multi_seasonal spectral data are necessary to determine whether similar patterns emerge and whether the approach has more general applicability in terms of characterizing remote sensing/spectral imagery and community types in saltmarsh vegetation.

QUANTITATIVE RELATIONSHIPS BETWEEN CANOPY SPECTRAL REFLECTANCE AND LEAF STOMATAL CONDUCTANCE IN RICE
TIAN Yong-Chao, ZHU Yan, YAO Xia, ZHOU Chang-Jun, CAO Wei-Xing
Chin J Plan Ecolo. 2006, 30 (2):  261-267.  doi:10.17521/cjpe.2006.0035
Abstract ( 2796 )   PDF (696KB) ( 824 )
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This investigation was conducted to determine the quantitative relatio nship between leaf stomatal conductance and canopy spectral reflectance of rice crops under different water and nitrogen regimes. Results showed that leaf stomatal conductance on main stem leaves under different water treatments decreased in the following order throughout the growth cycle: GsL1 > GsL2 > GsL3 > GsL4. The leaf stomatal conductance in the high nitrogen treatment was higher than in the low nitrogen treatment when the soil water content was above W3. Below W3, there were no significant differences in leaf stomatal conductance between the high and low nitrogen treatments. It also was found that the correlation between the ratio index R(1 650, 760) and stomatal conductance averaged over different layer leaves was the following: GsL1 > GsL12 > GsL123 > GsL1234 > GsL2 > GsL3 > GsL4 (GsL1, GsL2, GsL3, GsL4, GsL12, GsL123 and GsL1234 denoted the first, second , third, fourth leaf and two leaves, three leaves, four leaves from top). The best relationship was between canopy stomatal conductance (the product of GsL1 and LAI) and R(1 650, 760). The ratio index R(1 650, 760) showed a power relations hip with both stomatal conductance of L1 and canopy leaf stomatal conductance with an RMSE of 0.05 and 0.24, respectively. It was concluded that the ratio index R can be used to monitor leaf stomatal conductance during different growth stages of rice.

ANALYSIS OF HUMAN_INDUCED STEPPE DEGRADATION BASED ON REMOTE SENSING IN XILIN GOLE, INNER MONGOLIA, CHINA
CAO Xin, GU Zhi-Hui, CHEN Jin, LIU Jin, SHI Pei-Jun
Chin J Plan Ecolo. 2006, 30 (2):  268-277.  doi:10.17521/cjpe.2006.0036
Abstract ( 2846 )   PDF (700KB) ( 802 )
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Grassland degradation in arid and semi_arid steppe results from the integrated impacts of nature and human factors and is one of the most important ecological and economic issues in China. It is necessary to discriminate betweenn atural and human_induced degradation for purposes of rehabilitation and restoration of degraded steppe regions. Based on existing research, we proposed a method that integrated regression analysis and residual analysis to discriminate between areas degraded by human activities and those caused naturally. We applied this method to the Xilin Gole Steppe in Inner Mongolia, China as a case study using Pathfinder NOAA/AVHRR  NDVI data from 1983 to 1999 and meteorological data within the same time period. Firstly, we constructed a regression model using the first 6 years (1983_1988) of data for each pixel between annual maximal  NDVI and meteorological data (precipitation and temperature) including a time lag for precipitation. Secondly, the difference or residuals between actual and predicted maximal  NDVI were derived for the latter 11 years (1989-1999). The analysis of the trends in the residuals of the first data set over time indicated that pixels with negative trends were human_induced degradation. The results showed that the Xilin Gole Steppe experienced a heavier degree of human_induced degradation from 1989 to 1999 with larger areas being impacted. The results are in accord with the status quo of the study area.

CLONAL INTEGRATION MODIFIES RESPONSES OF HEDYSARUM LAEVE TO LOCAL SAND BURIAL IN MU US SANDLAND
LIU Feng-Hong, YE Xue-Hua, YU Fei-Hai, DONG Ming
Chin J Plan Ecolo. 2006, 30 (2):  278-285.  doi:10.17521/cjpe.2006.0037
Abstract ( 2484 )   PDF (670KB) ( 920 )
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In arid and semi_arid inland deserts, a major environmental stress for the plants is recurrent sand burial, which can influence the physical and biotic microenvironment of the plants and soil. Previous studies have shown that different sand burial depths have different effects on plants. Slight sand burial could increase the height increment, leaf biomass and the number of new ramets of the plants, while heavy sand burial impaired the growth of the plants and even decreased their survival. In other words, below a certain burial threshold level, the growth of the plants is stimulated probably because of multiple factors. However, as the level of burial increases, the positive response declines until it becomes a negative factor. Sand dunes are frequently colonized and stabilized by many rhizomatous clonal plants in arid and semi_arid inland deserts. Clonal physiological integration often helps clonal plants buffer local environmental stresses encountered by the ramets. The rhizomatous clonal semi_shrub, Hedysarum laeve, is a dominant plant species and important for vegetation restoration in the Mu Us sandland. We conducted a field experiment to investigate whether clonal integration can increase the threshold of sand burial and help rhizomatous H. laeve tolerate heavy sand burial. The results showed that slight sand burial could accelerate ramet growth and enhance their leaf biomass, stem biomass and shoot biomass. Heavy sand burial reduced the biomass of the plants and impaired survival and growth of the ramets. Clonal integration increased the thre shold of sand burial. Ramets connected to other ramets had greater height increm ent, stem biomass, leaf biomass and shoot biomass as compared to ramets that were not connected to other ramets under heavy sand burial. These results suggested that clonal physiological integration could help H. laeve ramets to tolerate relatively heavy sand burial, and clonal integration should play a role in H. laeve occupying the Mu Us sandland.

EFFECTS OF SOIL TEMPERATURE AND MOISTURE ON SOIL SURFACE CO2 FLUX OF FORESTS IN NORTHEASTERN CHINA
YANG Jin-Yan, WANG Chuan-Kuan
Chin J Plan Ecolo. 2006, 30 (2):  286-294.  doi:10.17521/cjpe.2006.0038
Abstract ( 2184 )   PDF (807KB) ( 1124 )
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Forest ecosystems in northeastern China play an important role in both local and national carbon budgets because of their large area extent and huge amount of carbon storage. The spatial and temporal changes in soil surface CO2 flux (RS), the major CO2 source to the atmosphere from terrestrial ecosystem s, directly influence the local and regional carbon budgets. However, few data on RS were available for this region. In this study, we used an infrared gas exchange analyzer (LI_COR 6400) to measure the RS and related biophysical factors, and examined soil temperature and moisture effects on soil respiration for six secondary temperate forest ecosystem types: Mongolian oak (dominated by Quercus mongolica), poplar_birch (dominated by Populus davidiana and Betula platyphylla), mixed_wood (no dominant tree species), hard_wood forests (dominated by Fraxinus mandshurica, Juglans mandshurica and Phellodendron amurense), Korean pine ( Pinus koraiensis) and Dahurian larch (Larix gmelinii) plantations. Our specific objectives were to: 1) compare the soil temperature, soil moisture, RS, and Q10 (temperature coefficient) of the six forest types; 2) quantify the seasonality of RS and related environmental factors; and 3) determine the environmental factors affecting the RS, and construct models of RS against the related environmental factors.  Soil temperature, soil moisture and their interactions significantly (p < 0. 01) influenced the RS, but their effects depended on forest type and soil depth. These factors could explain 67.5%－90.6% of the variations in the RS data. During the growing season, the soil temperature at 10 cm depth in the different forest types did not differ significantly but soil moisture did. The RS for the oak, pine, larch, hardwood, mixed_wood, and poplar_birch stands varied from 1.89－5.2 3, 1.09－4.66, 0.95－3.52, 1.13－5.97, 1.05－6.58, and 1.11－5.76 µmol CO2•m－2•s－1, respectively; the Q10values for those stands were 2.32, 2.76, 2.57, 2.94 , 3.55 and 3.54, correspondingly. The seasonality of RS was driven mainly by soil temperature and moisture, and was roughly consistent with that of soil temperature. The broad_leaved forests had a higher soil respiration rate than those of coniferous forests probably because of a more suitable soil thermal and moisture regimes and other biological factors.  The temperature sensitivity coefficient of soil respiration (Q10) showed a convex_type curve along a soil moisture gradient. The Q10tended to increase when soil moisture increased from 30.19 to 40.7, and then declined probably because the extremely high soil moisture content in the hardwood forest may impede activities of soil microbes and plant roots, and thus decrease decomposition rates and soil CO2 emission. Our study strongly recommended that estimation of soil surface CO2 flux from forest ecosystems should consider the comprehensive effects of both soil temperature and moisture on soil respiration so as to reduce uncertainties of ecosystem carbon budget studies in this region.

DIURNAL AND SEASONAL CO2 EXCHANGE ON CLEAR DAYS IN A TROPICAL SEASONAL RAINFOREST OF XISHUANGBANNA
ZHAO Shuang-Ju, ZHANG Yi-Ping, YU Gui-Rui, SONG Qing-Hai, SUN Xiao-Min
Chin J Plan Ecolo. 2006, 30 (2):  295-301.  doi:10.17521/cjpe.2006.0039
Abstract ( 2760 )   PDF (700KB) ( 756 )
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Tropical forests play an important role in altering the carbon budgets of terrestrial ecosystems. We examined patterns of diurnal and seasonal net ecosystem CO2 exchange (NEE) in a tropical seasonal rainforest of Xishuangbanna on clear days between November 2003 and October 2004. We found that the diurnal dynamics of NEE showed a single_peaked curve. During daytime throughout the year, NEE increased with solar radiation after sunrise, but fluctuated after sunset. Values of NEE (absolute values) in the foggy_cool and wet seasons were greater than those in the dry_hot season during daytime. During the night, NEE values were dominated by soil temperature and soil water content and were highest in the wet season, followed by those in the dry_hot season and lowest in the foggy_cool season. NEE, water vapor deficit (VPD) and air temperature (Ta) curves all showed pronounced seasonal variation, but photosynthetically available radiation (PAR) did not vary significantly. Maximum photosynthesis rates (Pmax) and dark respiration rates (Re) were greater when VPD≥16 hPa than when VPD<16 hPa , whereas photon density (α) was the opposite. Re was also greater when Ta≥25 ℃ than when Ta< 25 ℃ in the three seasons.α was reduced when Ta≥25 ℃ in the dry_hot and wet seasons. The Pmax increased in the dry_hot season and decreased in the wet season when Ta≥25 ℃. Our data suggested that PAR is the main factor influencing NEE diurnal dynamics, whereas both VPD and Ta play a major role in regulating NEE seasonal dynamics.

RELATIONSHIP BETWEEN HERBACEOUS ROOT SYSTEM AND VERTICAL SOIL SEDIMENT YIELD IN LOESS AREA
LI Peng, LI Zhan-Bin, LU Ke-Xin
Chin J Plan Ecolo. 2006, 30 (2):  302-306.  doi:10.17521/cjpe.2006.0040
Abstract ( 2294 )   PDF (455KB) ( 787 )
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Current knowledge about root morphology and its impacts on soil erosion is limited and, therefore, detailed analyses of root system in controlling soil erosion are needed. In order to determine the effects of root system on soil erosion quantitatively, root investigation and stratified runoff scouring were conducted in field. The distribution of vertical root biomass on three sites decre ased with the increase of soil depth in a similar manner. Most roots were concen trated in surface soil, and decreased to less than 0.2 kg•m-3 in soil below the depth of 40 cm. There was no significant difference in root biomass on the same soil depth from different points. Results from stratified runoff scouring on different soil depths in the field indicated that, on the surface soil layer, the existence of root could effectively improve soil resistance to runoff erosion, and its effect on sediment yield was dominant. While in deeper soil, sediment yield increased with the decrease of root distribution, and was more related to slope gradient, runoff discharge and soil properties. In addition, with the progress of runoff scouring, the form of soil erosion changed from sheet erosion to rill erosion. Investigation of the root distribution patterns revealed that the vertical sediment yield was closely related to root distribution characteristics. Further analysis of the root distribution pattern and the vertical sediment yield allowed establishment of a quantitative relationship between root biomass and vertical sediment yield.

EFFECTS OF SEAWATER TREATMENTS ON THE PHYSIOLOGICAL AND BIOCHEMICAL CHARACTERISTICS OF HELIANTHUS TUBEROSUSSEEDLINGS AND RESPONSE TO PHOSPHORUS SUPPLY
LONG Xiao-Hua, LIU Zhao-Pu, XU Wen-Jun
Chin J Plan Ecolo. 2006, 30 (2):  307-313.  doi:10.17521/cjpe.2006.0041
Abstract ( 2019 )   PDF (582KB) ( 743 )
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Growing plants that are tolerant to salt_water is one option for exploiting mudflats along the coast. Pot experiments were carried out to study the effects of seawater on growth, inorganic and organic osmotic, antioxidant enzyme, membrane permeability in Helianthus tuberosus seedlings and response to phosphorus supply. The results showed that 1) compared with the control, the fresh weights of roots and aerial parts of Helianthus tuberosus seedlings treated with 10 % seawater changed slightly, even were higher than the control, whereas decreased with treatment of 25% seawaters. The fresh weights of roots and aerial parts increased with the concentration of phosphorus augment. The trends of dry weights of roots and aerial parts resembled the trends of fresh weights with the same treatments. 2) The contents of proline and soluble_sugar increased obviously with inc reasing seawater concentrations. The contents of proline and soluble_sugar increased on 8 days and decreased on 12 days after the treatments of 10% and 25% seawater. They both increased with phosphorus augment. 3) The activities of SOD, POD and CAT in leaves of seawater_stressed plants were significantly stimulated compared to control plants, and the trends toned up with increasing seawater concent rations. The activities of SOD, POD and CAT all significantly stimulated with phosphorus augment. 4) Compared with the control, there was slight change of MDA content in leaves of Helianthus tuberosus seedlings treated with 10% seawater. The MDA content and ELP significantly increased with the treatment of 25% seawater . They both decreased with phosphorus augment. 5）The Na+ and Cl- contents of the aerial parts and roots significantly increased with increasing seawater concent rations and time lasting. And the contents of Na+ and Cl- decreased with phosphorus augment. Compared with the control, the contents of K+, Ca2＋ and Mg2＋of the aerial parts and roots increased, and they all increased with phosphorus augment. Above all, phosphorus can improve nutrition and increase resisting salinity for Helianthus tuberosus seedlings.

LEAF ANATOMY OF DOMINANT PLANT SPECIES IN THE SUCCESSIONAL COMMUNITIES OF XIANGSHAN MOUTNAIN, HUAIBEI, CHINA
SHI Gang-Rong, TANG Ying, ZHANG Zheng
Chin J Plan Ecolo. 2006, 30 (2):  314-322.  doi:10.17521/cjpe.2006.0042
Abstract ( 2487 )   PDF (705KB) ( 937 )
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The results of eco_anatomical observations on the leaf blades of 5 dominant species in a mixed forest of Xiangshan Mountain, Huaibei, China, indicated that these species share some xeromorphic characteristics such as a developed epidermal cuticle or hairs, total_palisade or flourishing palisade tissue, and developed vascular tissue in middle vein. Ziziphus jujuba var. spinosa and Vitex negundo var. cannabifolia , the two dominant species widely distributed throughout Xiangshan Mountain, show great plasticity in their lamina structure in two aspects: 1) Within the same community, the lamina structure shows temporal developmental plasticity with leaves collected at the beginning of May being more characteristic of sun plants as compared to those in mid September; 2) In different successional community, lamina structure are indicative of environmental plasticity. The shrub_herb communities tend to have xeromorphic/sun leaves, shrub communities have xerom orphic/sun leaves, the sparse mixed forest has mesophytic/sun leaves, and the Platycladus orientalis forest has mesophytic/shade leaves. These differences in leaf anatomy reflect both the ability for plants to adapt heterogeneous habitats as well as differences in the environment of the different communities. The results of non_parameter correlation analysis showed that the lamina structure was in fluenced by many environment factors, with soil water content, relative humidity and wind velocity being the principle factors. Lamina anatomical characteristics, such as cuticle thickness of the upper epidermis, stomatal density, thickness of the palisade tissue, leaf thickness, xylem thickness and bundle thickness of the middle vein, all were negatively correlated to soil water content and relative humidity and positively correlated to wind velocity.

AN EFFECTIVE IN VITRO PROTOCOL FOR INCREASING MYCORRHIZAL FORMATION RATE OF CATHAYA ARGROPHYLLA
XING Shu-Tang, LI Yu-Hua, SUN Xue, LUN Zhi-Ming, VAARIO Lu-Min
Chin J Plan Ecolo. 2006, 30 (2):  323-329.  doi:10.17521/cjpe.2006.0043
Abstract ( 2573 )   PDF (654KB) ( 789 )
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An effective in vitro ectomycorrhizal formation protocol of Cathaya argyrophylla, which is an endangered important tree belonging to the family Pinaceae, has been developed. Over 60% of the seeds germinated following 7 d on an agar medium that were treated by cutting and removing 1/5-1/3 of the seed coat and endosperms. A modified MS medium (MMS) containing 1/4 concentration of macro elements, 1/2 concentration of micro elements and full concentration of Fe salt and vitamins of the MS medium was used for seedling growth of C. argyophylla. An RM medium provided appropriate growth conditions for the hyphae of Cenococcum geophilum. The RM medium resulted not only in more rapid growth but also in progressively smoother fungal layers resulting in a thin homogeneous myceliamat upon the medium surface. The growth of C. argyophylla on the MMS medium was compared to growth on the RM medium. The results showed that seedlings of C. argyophylla also grew well on the RM medium. Therefore, the RM medium was selected for in vitro ectomycorrhizal formation between C. argyophylla and C. geophilum. To solve the problem of sterilization of non_autoclavable containers, surface sterilization was achieved by 70% ethanol solution or 0.05% NaOCl solution followed by ultraviolet radiation. The results showed that all treated containers were sterilized and 87.5% of seedlings were mycorrhizal seedlings. This method will facilitate detailed studies on ectomycorrhizal development of C. argyrophylla and on ectomycorrhizal seedling applications.

THE EFFECTS OF ANTIOXIDANTS ON THE TRANSIENT EXPRESSION OF GUS GENE IN SOYBEAN HYPOCOTYLS MEDIATED BY AGROBACTERIUM TUMEFACIENS
JI Feng-Yuan, WANG Ge-Liang, XU Yi-Nong
Chin J Plan Ecolo. 2006, 30 (2):  330-334.  doi:10.17521/cjpe.2006.0044
Abstract ( 2765 )   PDF (443KB) ( 761 )
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Soybean hypocotyls have advantages of higher regeneration frequency and faster formation of adventitious shoots, and often be used in soybean transformation mediated by Agrobacterium tumefaciens. But the browning and necrosis of hypocotyls during co_cultivation greatly affects the efficiency of the transformation.The effects of antioxidants on the transient expression efficiency of GUS  (β-glucuronidase) gene in soybean hypocotyls mediated by Agrobacterium tumefaciens were studied by adding antioxidants (thiosulfate, L_cysteine, and dithiothreitol) in the co_cultivation medium，and the transient expression efficiency of the GUS gene was measured by histochemically method. The results showed that the antioxidant in the co_cultivation medium increased the transient expression efficiency up to 23.4% in hypocotyls. Further investigation demonstrated that higher transient expression efficiency was associated with concomitant decreases in the levels of hypocotyl browning. The stable expression of GUS gene in hypocotyls was found in the cambium cells, which was formed as deep blue zone on the hypocotyls. Our results also showed that concentration of Agrobacterium tumefaciens and co_cultivation time were the important factors that affected the transient expression efficiency of GUS gene in hypocotyls. In our experiments, the highest transient expression efficiency of GUS gene obtained by inoculating hypocotyls in Agrobacterium tumefaciens (OD600 0.6) and co_cultivating for 3 days in the darkness . All results suggested that antioxidants could efficiently improve transient expression efficiency of GUS gene in soybean hypocotyls.

EFFECTS OF LOW TEMPERATURE ON PHYSIOLOGICAL MECHANISMS OF COTTON FIBER STRENGTH FORMING PROCESS
JIANG Guang-Hua, MENG Ya-Li, CHEN Bing-Lin, BIAN Hai-Yun, ZHOU Zhi-Guo
Chin J Plan Ecolo. 2006, 30 (2):  335-343.  doi:10.17521/cjpe.2006.0045
Abstract ( 2358 )   PDF (603KB) ( 764 )
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It is believed that the thickening process of fiber in cotton is affected by low temperature as late seeding often produces poor quality cotton. Effects of temperature on the physiological mechanisms of cotton fiber strength forming processes were studied to determine whether low temperature was responsible for the bad quality of late maturing cotton by regulating temperature during growth. The results of a 2_year experiment showed that mean daily temperature of 24.0 ℃ during the boll stage between 25 to 50 days formed high_strength cotton fiber. Cotton fiber sucrose synthetase activity was the highest, β-1,3-glucanase activity was the lowest, and cellulose accumulation and accumulation rates were the highest at this temperature. When mean daily temperature was lower than 21.0 ℃, enzyme activity related to cotton fiber thickening development was reduced resulting in lower fiber strength. When mean daily temperature were around 15.0 ℃, the fiber sucrose synthetase activity evidently fell, β-1,3-glucanase activity incr eased, and quantity of cellulose accumulated and accumulation rate evidently declined. In this case, cotton fiber development was abnormal, and boll weight was only 3.22 g, and fiber strength only 15.73 cN•tex－1.

EFFECT OF NITROGEN AND PHOSPHORUS LEVEL AND SOWING DATE ON DYNAMIC CHANGE IN GRAIN FALLING NUMBER IN SPRING WHEAT IN GRAIN FILLING
ZHAO Xiu-Lan, LI Wen-Xiong
Chin J Plan Ecolo. 2006, 30 (2):  344-351.  doi:10.17521/cjpe.2006.0046
Abstract ( 2629 )   PDF (662KB) ( 713 )
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Wheat grain falling number (GFN) is an important index that indicates the alpha_amylase activity and starch quality properties of wheat. The temporal dynamics of GFN and the effects of environmental conditions on GFN during grain filling have been scarcely reported systematically in the literature. In the present paper, field experiments were carried out in Harbin in 2002 to investigate temporal patterns in GFN, and how GFN was affected by N and P treatments and meteorological conditions during grain filling. Three genotypes of spring wheat with different qualities were used: a high protein_rich gluten genotype (Wildcat') , a high protein_medium gluten genotype (DN7742') and a low protein_poor gluten genotype (`NKH9'). The N and P applications included four treatments: 225 kg•hm-2 N, 450 kg•hm-2 P2O5 (F1); 300 kg•hm-2 N, 300 kg•hm-2 P2O5 (F2); 300 kg•hm-2 N, 450 kg•hm-2 P2O5 (F3) and 300 kg•hm-2 N, 600 kg•hm-2 P2O5 (F4). The results showed that temporal changes in GFN after anthesis could be fitted with a third_order convex curve (single peak curve), indicating that GFN rose in the initial stages and then fell during the middle and upper stages of grain filling. The effects of genotype and environmental factors on GFN formation were compared using t his fitted curve. The temporal pattern in alpha_amylase activity fell to a greater extent during the initial stage and then rose weakly in the medium and upper stage. The results also indicated that from the 15th day after anthesis to maturity, with increasing nitrogen levels, medium phosphorus and high potassium levels (450 kg•hm-2 P2O5, 600-630 kg•hm-2 K2O), GFN in the high protein_rich gluten genotype increased and the peak value rose but was delayed, and GFN decreased and the curve peak values fell but was ahead in both the high protein_medium gluten and low protein_poor gluten genotypes. GFN in the three genotypes all decreased with increasing phosphorus levels in the medium or low nitrogen treatments and at high potassium levels (300 kg•hm-2 N, 600－610 kg•hm-2 K2O) , and the curve differed among the three genotypes. The balance of nitrogen, phosphorus and potassium inputs was the key to forming higher GFN (lower alpha_amylase activity) . Under conditions of moderate rainfall, the interaction of temperature and sunlight was the predominant influence on temporal formation patterns of GFN for different genotypes during grain filling, rainfall was the second, and PAR was the most sensitive among all the meteorological elements influencing the dynamic formation of GFN. Higher GFN was formed in all genotypes under conditions of high sun light and high temperatures. Under conditions of high sunlight and temperature, the GFN in the high protein_rich gluten genotype increased with increasing PAR. The effects of meteorological conditions as well as differences among enotypes on GFN could be modeled by curve changes in the third_order equation. The variation o f GFN in different genotypes under different environmental conditions (nitrogen and phosphorus fertilization and meteorological conditions) had significant affects on GFN.

ACCUMULATION DYNAMICS OF PROTEIN AND STARCH COMPONENTS IN GRAIN OF TWO WINTER WHEAT CULTIVARS WITH DIFFERENT CANOPY TEMPERATURE CHARACTERISTICS DURING THE FILLING STAGE
ZHU Yun-Ji, MA Dong-Yun, LI Xiang-Yang, GUO Tian-Cai, WANG Chen-Yang
Chin J Plan Ecolo. 2006, 30 (2):  352-358.  doi:10.17521/cjpe.2006.0047
Abstract ( 2506 )   PDF (588KB) ( 834 )
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Canopy temperature during the grain filling stage can affect grain yield and quality. Previous studies have focused on the effects of canopy temperature on physiological characteristics and yield, and its measurements have been used widely in recent years to study genotypic responses to drought and heat stress. This paper aims to understand the effects of canopy temperature on the main quality traits of winter wheat (Triticum aestivum) cultivars. The dynamic changes in the accumulation of protein and starch components during the filling stage in the grain of winter wheat cultivars with different canopy temperature characte ristics were studied in Henan Province over two growing seasons (2001 _ 2003). The results indicated that the canopy temperature of the three cultivars changed a lot during the filling stage. During the early stage, average canopy temperatures were maintained but there was a strong change in temperature among the cultivars during the mid and late filling stage, especially in the late filling stage. In the mid and late stage, the canopy temperature of ‘Yumai 50’ decreased and expressed a cold tail type. The canopy temperature of ‘Yumai 34’ and ‘Yumai 7 0’ tended to rise at the mid and late stages and expressed a warm tail type. The difference in canopy temperatures between the cold and warm tail type cultivars could be greater than 2 ℃. There were differences in patterns of protein and starch accumulation in the grain among cultivars. Accumulation of albumin, globulin and glutenin were significantly different in the late grain filling stage between warm and cold tail type cultivars, but there were no differences in gliadin accumulation. No significant differences of glutenin accumulation was observed within 15 d post_anthesis, but by 20 d after anthesis, significant differences (1% level ) were observed between the two cultivars with different canopy temperature characteristics during the grain filling stage. Accumulation content of glutenin of ‘Y umai 34’ and ‘Yumai 70’ at harvest were 46.19% and 19.7% higher than ‘Yumai 50’, respectively. The ratio of glutenin to total protein showed the same trend and indicated that the rising canopy temperature during the filling stage resulted in higher accumulations of glutenin. The content of glutenin was positively and significantly correlated with canopy temperature in the mid, late and total grain filling stage. The content of starch and amylose/amylopection during the grain filling stage did not show significant differences between the two types of cultivars, but significant differences (1% level) were found in pasting parameters, such as the peak of viscosity, through viscosity, final viscosity, pasting time, pasting temperature and setback value with the exception of the breakdown value. In particu lar, through viscosity of ‘Yumai 34’ and ‘Yumai 70’ were both 84.4% higher than that of ‘Yumai 50’, and final viscosity was 60.9%, 58.2% higher than that of ‘Yumai 50’, respectively.

ANALYSIS ON SOME MISTAKES IN THE APPLICATION OF STATISTICS IN ECOLOGICAL RESEARCHES
ZHANG Feng, WU Yu-Zhen, ZHANG Gui-ping, RU Wen-ming
Chin J Plan Ecolo. 2006, 30 (2):  361-364.  doi:10.17521/cjpe.2006.0048
Abstract ( 2940 )   PDF (428KB) ( 1621 )
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The application of statistical methods in ecological researches is more and more extensive, and it is very important for improvement and development of ecologica science. However, there are some mistakes when statistical methods are applied to ecological researches, 1) Regression analysis: correl ation index, R2, was incorrectly used to test whether a simple regression equation was significant or not. Correlation coefficient, r, was inappropriately used to describe the significance of curve regression e quations. Moreover, multiple linear regression equation was only tested by analysis of variance (ANOVA), but each regression coefficient in the equation was not tested; 2) ANOVA. t_test was applied inappropriately to test significance of the means of all treatments when the treatments in an experiment were more than 2. The reasons for these mistakes were investigated and methods to avoid these mistakes were introduced.

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