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Table of Content
    Volume 43 Issue 7
    20 July 2019
      
    Divergent responses of plant functional groups to precipitation in grassland
    Chin J Plant Ecol. 2019, 43 (7):  0-0.  doi:10.17521/cjpe.2018.0230
    Abstract ( 91 )   PDF (440KB) ( 36 )   Save
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    Abstract Aims Variability of precipitation plays a key role in regulating the effects of climate change to community assembly and functioning of ecosystem (CAFE) in arid and semi-arid grassland regions. Plant functional groups (PFGs), as the basic components in constituting CAFE, vary with their identities (i.e., identity-dependent) in response to climate change. Here, we examine how the PFGs respond the variation of precipitation and contributing to alter the response of plant community aboveground biomass (AGB) to climate change. Methods We have conducted a long-term ecological research of AGB since 1982 in the typical steppe grassland of Inner Mongolia, China. We used the monthly-observation dataset from 1982 to 2015. Important findings We found that 1) the precipitation-concentration degree (PCD) was declining with an increase of small rainfall events (≤ 5 mm) in last 35 years; 2) precipitation pulse caused a decrease of AGB, in particularly annuals and biennials (AB),perennial forbs (PF),and perennial rhizome grass (PR), conversely increasedperennial bunchgrasses (PB); 3) AGB, perennial forbs (PF) and semi-shrubs (SS) were positively associated with growing season rainfall, and AGB was positively correlated to PCD while shrubs (S) was negatively correlated to PCD; 4) AGB had a negative correlation with contribution percentages about I-II precipitation toannual precipitation; 5) AGB had the negative correlations with frequency of occurrence and contribution percentages in both I precipitation(0.1-5 mm)and VI precipitation(20-25 mm).It is concluded that the increase of small precipitation events will significantly reduce the community aboveground biomass. Small precipitation events have important ecological significance for vegetation growth in arid and semi-arid regions.
    Patterns and affecting factors of nitrogen use efficiency of plant leaves and roots in Inner Mongolia and Qinghai-Xizang Plateau grasslands
    FU YIWen Da-Shuan TIAN Jinsong Wang Zhao KenTian
    Chin J Plant Ecol. 2019, 43 (7):  0-0.  doi:10.17521/cjpe.2019.0044
    Abstract ( 44 )   PDF (841KB) ( 7 )   Save
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    Abstract Aims Nitrogen use efficiency (NUE) is a key functional trait in plants, which closely relates to ecosystem functions. However, it is still unclear about the regional patterns and affecting factors of plant NUE. Methods This study analyzed leaf or root NUE response patterns with environmental factors and plant functional groups in 139 grassland plant species from 82 sampling sites of Inner Mongolia and Qinghai-Xizang Plateau. Important findings 1) We found that leaf NUE (53 g·g-1) in meadow steppe was significantly greater than those in alpine meadow (46 g·g-1), desert steppe (41 g·g-1) and typical steppe (39 g·g-1). Root NUE (108 g·g-1) in alpine meadow was higher than those in other ecosystems. 2) Leaf NUE was more sensitive to temperature than root NUE, but with increasing drought index they all showed a significant decrease. 3) Leaf and root NUE in forbs were significantly lower than sedges and grasses. In addition, there was a NUE reduction of 48% and 60% in legume than non-legume leaf and root respectively. 4) No relationship was existed between plant NUE and soil nitrogen content. Overall, there was some difference in the spatial patterns between leaf and root NUE in the Inner Mongolia and Qinghai-Xizang Plateau grasslands. The main impacting factors were plant functional group and drought index. This study systematically reveals the spatial patterns of plant NUE in both types of grasslands and the key influential factors. These results are helpful to understand the mechanisms maintaining grassland productivity in China under global change, providing more scientific evidence for grassland management.
    13C pulse labeling reveals the effects of grazing on assimilate carbon partitioning in an alpine meadow
    Chin J Plant Ecol. 2019, 43 (7):  0-0.  doi:10.17521/cjpe.2019.0009
    Abstract ( 33 )   PDF (637KB) ( 3 )   Save
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    Aims In this study, we aim to understand how grazing influence assimilate carbon partitioning based on our long-term winter light grazing and enclosure experiment in an alpine meadow on the Qinghai-Xizang Plateau. Methods We use the 13C tracer method to reveal the effects of light grazing on assimilate carbon partitioning and C transition in different carbon pools. Important findings The results showed that 13C in shoot of grazed plots accounted for about 32% of 13C content at the beginning, 13C in root and soil accounted for about 22%, and 13C loss through shoot respiration accounted for about 30% on the 30th day after 13C labeling. In the two different treatments of light grazing and enclosure, there is a significant difference in the retention of photosynthetic carbon in the soil and the rate of release of photosynthetic carbon with soil respiration. Under light grazing treatment, plants invested more photosynthetic carbon into root and soil carbon pools. Compared with enclosure treatment, 13C input rate from shoot to the soil was faster in light grazing treatment, and release rate through soil respiration was the fastest, while the recovery rate of 13C in shoot and shoot respiration was low. Grazing is an important management method of grassland. Grazing can cause changes in the structure and function of ecosystems, and induce large variation in soil carbon storage. Alpine meadow in the Qinghai-Xizang Plateau is one of grasslands with the highest elevation in the world. Alpine meadow has large soil carbon storage due to low temperature. Our results showed that there is no difference in soil C stocks in grassland ecosystems due to light grazing and fence enclosure. And light grazing does not have a significant impact on soil carbon stocks.
    Diversity and geographical variations of germplasm resources in Armeniaca mandshurica
    Hao XU Ming-Guo LIU shengjun dong yueliang wu haokai zhang
    Chin J Plant Ecol. 2019, 43 (7):  0-0.  doi:10.17521/cjpe.2019.0060
    Abstract ( 201 )   PDF (977KB) ( 12 )   Save
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    Abstract Aims Armeniaca mandshurica is an important species which serves the need of appreciation, economical use and wood. It has been in wild or semi-wild state for a long time so that few related studies have been conducted. This paper aimed to provide an important reference for the collection, evaluation and protection of germplasm resources in A. mandshurica. Methods The status of germplasm resources in the main distribution area of A. mandshurica was investigated, 47 typical sample trees from Liaoning, Jilin and Heilongjiang Province were selected for observation of 19 quantitative description traits and 7 qualitative description traits. The diversity of quantitative description traits was analyzed by using indicators such as coefficient of variation, and the diversity of qualitative description traits was analyzed by using indicators such as frequency distribution. The geographical variation regularity of quantitative description traits was analyzed by the trend surface method. A total of 115 pairs of SSR primers were used for PCR amplification for 47 A. mandshurica germplasms, and the genetic diversity of A. mandshurica germplasms was analyzed by using genetic similarity coefficient. Germplasms were classified by cluster analysis separately based on phenotypic traits and SSR markers. Important findings High phenotypic diversity was presented among different germplasms in A. mandshurica, and the coefficients of variation of 19 quantitative description traits were ranged from 9.40% to 55.98% where the largest coefficient of variation was twig length and the smallest coefficient of variation was kernel width; the Shannon-Wiener index of 7 qualitative description traits ranged from 0.58 to 1.22. Due to the significant correlation between geographical locations and main climatic factors of survey area, the quantitative description traits of A. mandshurica germplasms were closely related to their geographical locations. Among them, twig length showed a gradient variation of increasing from east to west, twig thickness and seed mass showed a gradient variation of increasing from north to south, fruit handle length showed a gradient variation of increasing from northeast to southwest; twig length and fruit handle length were positively correlated with altitude, twig thickness was negatively correlated with altitude, seed mass was little correlated with altitude. System clustering based on 26 phenotypic traits showed that 47 A. mandshurica germplasms could be divided into 4 categories, which mainly reflected the difference of the germplasm characteristics in A. mandshurica and to some extent also reflected the effect of germplasm productions; clustering analysis based on genetic similarity coefficients showed that 47 A. mandshurica germplasms were also divided into 4 categories, which reflected the effect of germplasm productions; Chi-square test showed that the correlation between the two clustering results was not significant, and the external environment was the key factor affecting phenotypic variations in Armeniaca mandshurica.
    Changes of potential geographical distribution for Tsoongiodendron odorum since Last Glacial Maximum
    Chin J Plant Ecol. 2019, 43 (7):  0-0.  doi:10.17521/cjpe.2018.0258
    Abstract ( 365 )   Save
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    Aims Tsoongiodendron odorum Chun is an ancient relic belonging to the family Magnoliaceae, but it is labelled endangered plant with extremely small populations and facing a serious threat of wild survival now. Using Ecological Niche Modelling (ENM) to project historical changes of species distribution pattern histories following the Last Glacial Maximum (LGM), this study aims to explore the impact of climate change on the distribution of T. odorum, and to evaluate the relationship between species distribution and determinant variables, so as to provide a framework for the conservation in the context of global warming. Methods Based on 96 modern geographical distribution records and 8 bioclimatic variables, we simulated the potential distribution of T. odorum during the LGM, Mid-Holocene, present and future (Period of 2061-2080 in the Representative Concentration Pathway 8.5 climate scenario) with MaxEnt model. The changes in distribution pattern were analyzed by SDM toolbox, while the importance of bioclimatic variables was evaluated by percent contribution, permutation importance and Jackknife test. Important findings (1) The highly suitable region of T. odorum was at Nanling region, and this area might be the glacial refugia that T. odorum survived in situ during the LGM because only slightly southward retreat was detected in LGM scenario. (2) In the two warming climate scenarios (Mid-Holocene and future), the area of the suitable region was reduced, while the decrease of future distribution is greater, which suggest that the warming climate might have a negative impact on the growth of T. odorum. (3) Overall the stability of geographical distribution range of T. odorum in each period indicates a certain extent climate adaptation. Human activity or self-breeding problem was likely the significant cause leading to endangered condition. Guangdong and Guangxi should be regarded as priority conservation areas by our results.
    Nestedness pattern detection of highly asymmetric networks in null model analysis
    Li-Tao Lin Ke-Ming MA
    Chin J Plant Ecol. 2019, 43 (7):  0-0.  doi:10.17521/cjpe.2019.0065
    Abstract ( 47 )   PDF (1155KB) ( 3 )   Save
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    Aims Null model is an important basis for nesting judgment. High asymmetry structure often appeared in plant symbolic fungal networks. Methods This paper aimed to explore the influence of matrix asymmetric change on the network nesting judgment based on various null model construction methods.. Important findings Constraints are different among different null models, reducing null space with adding qualifications during null model establishment. Highly constrained nulls are prone to cause type Ⅱerrors. Highly asymmetric network increased NT deviation whereas reducing NODF deviation basing on random null model, and the z-score showed that high asymmetric network contributed to the significant determination of NT and NODF. Row or column constrained null model showed different impact on the judgment of nestedness of asymmetric networks. Effect of network asymmetry change on nesting de-tection basing on column constrained nulls showed similar variation pattern with that of random null model, but lower nesting deviation and standard deviation. No significant difference of NT and NT de-viation were observed among different asymmetry networks basing on the row constrained nulls, with a lower NODF deviation in highly asymmetric network comparing with column constrained nulls. To more accurately determine whether asymmetrical networks have nested structures or not, we recommend using a combination of random and constrained null models. Result showed that r0 null model was better than r00 and c0 null models, when nesting level of different asymmetric networks were compared.
    The effects of long-term vegetation cover changes on the carbon fractions in soil aggregates of Mollisols
    Zhang Yihe Han Xiaozeng You Mengyang Hao Xiangxiang
    Chin J Plant Ecol. 2019, 43 (7):  0-0.  doi:10.17521/cjpe.2019.0028
    Abstract ( 36 )   PDF (669KB) ( 4 )   Save
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    Aims Soil aggregate is the main habitat for decomposition and transformation of soil organic carbon (SOC). It’s the key to regulate SOC sequestration. The stability mechanisms of SOC fractions may vary among different aggregate sizes. The aims of this study are to explore the SOC “fractionation” characteristics of aggregates, and to reveal the C sequestration mechanisms within soil aggregates after 31-year different vegetation cover in Mollisols. Methods A long-term field vegetation cover experiment (grassland, farmland and bare land) was established in Hailun Station of Chinese Academy of Sciences. Soil aggregate fractionation, further density and humus fractionation within different aggregate sizes were carried out. Important findings The results showed that after 31 years of grassland (GL), farmland (FL) and bareland (BL) treatments, the surface SOC and total nitrogen (TN) contents in GL with higher C inputs increased significantly, while the SOC and TN contents decreased in FL and BL, and significance were found in BL. The 2–0.25 mm aggregates was the excellent fraction in all three treatments. The stability of soil aggregate fell in the order of: GL > FL > BL. The mass proportion of soil aggregate and its associated content significantly improved in GL, and the proportion of microaggregate and its carbon allocation rate decreased. However, due to the lower C inputs in FL and BL, the distribution of aggregates was microaggregate > macroaggregate > silt-clay fraction, and OC content was higher in microaggregates. Different vegetation cover caused the C “fractionation” of density and humus fractions in aggregates. Compared with FL and BL soils, OC contents in light fractions in >2 mm and 2–0.25 mm aggregates were higher in GL, and the OC contents in FA, HA and HU were highest in 2–0.25 mm aggregates, while the humus OC in microaggregates were accumulated in FL and BL. Our results indicated that the plant-derived C entered into macroaggregates firstly, long-term grassland enhanced free and light C fractions in macroaggregate, which consequently improved the stability of soil aggregates and enhanced the “fractionation” effects of large aggregates on the humus fractions. Our results revealed that the carbon sequestration characteristics of soil aggregates under different vegetation cover in mollisol. The C “fractionation” characteristics in aggregates can provide theoretical basis and significant guidance for the study of soil carbon sequestration mechanism and optimization of black soil utilization.

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