放牧和模拟降水对短花针茅荒漠草原植物功能群多样性的影响

为探究放牧和降水变化对植物功能群的影响,本文以内蒙古短花针茅(Stipa breviflora)荒漠草原为研究对象,开展了野外控制试验。试验设置围封和适度放牧,分别进行模拟降水处理(减少降水量50%、自然降水、增加降水量50%、增加降水量100%),并在每年8月观测植物群落组成。结果表明:减水会降低植物功能群多样性、生物量和物种数量,增水有利于植物功能群多样性的提高。多年生丛生禾草多样性随降水量的增加而升高。同时,对降水梯度和功能群多样性进行拟合分析发现,降水量低于年降水量16%则不利于除灌木、半灌木外其他功能群植物的生长。围封草地增水67%~79%时,功能群的Simpson指数、Shannon-Wiener指数、Pielou指数值均较高,功能群多样性较高;由于放牧提高了植物的水分利用效率,放牧地各指数在增水26%~50%时较高,功能群多样性较高。综上,适度的放牧及水分补充有利于提高植物功能群多样性。

高寒草地植物物种多样性与功能多样性的关系

物种多样性与功能多样性的关系是生态学当前研究的热点问题之一,不同区域典型生态系统物种多样性和功能多样性的关系研究有利于生物多样性保护理论的全面发展。以青藏高原地区的主要草地生态系统—高寒草甸和高寒草原为研究对象,采用4个物种多样性指数(Patrick丰富度指数、Shannon-Weiner多样性指数、Pielou均匀度指数和Simpson优势度指数)和9个功能多样性指数(FAD功能性状距离指数、MFAD功能性状平均距离指数、基于样地的FDp和基于群落的FDc功能树状图指数、FRic功能体积指数、FEve功能均匀度指数、Rao功能离散度常二次熵指数、FDiv功能离散指数、FDis功能分散指数),分析了高寒草地植物物种多样性、功能多样性关系及其与初级生产力的关系,以期阐明3个科学问题:不同草地类型的高寒草地生态系统植物物种多样性和功能多样性有何差异?高寒草地生态系统的植物物种多样性和功能多样性有何关系?高寒草地生态系统物种多样性、功能多样性对生态系统功能的影响有何异同?研究结果表明:(1)与高寒草原相比,高寒草甸具有更高的物种多样性、功能丰富度和功能离散度;(2)高寒草甸中,Patrick丰富度与功能丰富度指数(FAD、MFAD、FDp、FDc)和功能离散度指数(FDiv)的具有较强的相关性,最优拟合方程分别为幂函数和二次多项式函数;(3)高寒草原中,Patrick丰富度与功能丰富度指数(FAD、MFAD、FDp、FDc、FRic)、Shannon指数和Simpson指数与FEve指数的相关性较强,最优拟合方程为二次多项式函数,Pielou指数与FEve指数的相关性较强,最优拟合方程为指数函数;(4)高寒草甸的初级生产力分别与物种丰富度指数Patrick、功能离散指数FDiv具有较强的相关性;而高寒草原的初级生产力与4个物种多样性指数间均具有较强的相关性,与功能离散指数FDiv具有较强的相关性,最佳拟合方程均为二次多项式函数。研究的总体结论为:物种多样性、功能多样性、二者之间的关系以及二者与生态系统服务功能(以初级生产力为例)之间的关系在高寒草甸和高寒草原群落中表现迥异,因此在研究青藏高原高寒草地的生态功能时,不能仅仅测度传统的物种多样性,还应测度与物种多样性、生态功能密切相关的功能多样性。

高原鼠兔对高寒草甸植物物种多样性和功能多样性关系的影响

草地植物物种多样性和功能多样性的关系会因环境改变而变化。高原鼠兔干扰往往会改变其巢域范围内高寒草甸的水热过程,但尚不清楚其是否影响高寒草甸植物物种多样性和功能多样性的关系。本研究在甘肃碌曲、青海祁连和共和县同步选择调查区,每个调查区采用配对设置样地的方法,分析了高原鼠兔干扰对高寒草甸植物物种多样性和功能多样性关系的影响。结果表明:高原鼠兔干扰显著增加了物种丰富度指数和物种多样性指数,而没有明显影响物种均匀度指数。高原鼠兔干扰显著增加了功能丰富度指数(P<0.05),但没有显著影响功能均匀度指数和功能离散度指数。高原鼠兔干扰促进植物功能丰富度指数与物种丰富度指数的关系从对数函数关系转变为二次函数关系,植物功能均匀度指数与物种均匀度指数的关系从不显著相关变为显著正相关;高原鼠兔干扰显著减弱了植物功能丰富度指数与物种丰富度指数、植物功能丰富度指数和物种多样性指数间的正相关性、植物功能离散度指数与物种丰富度指数的负相关性,增加了植物功能离散度指数和植物物种多样性指数间的负相关性。这为解读高原鼠兔干扰下植物群落物种共存机制提供了基础信息,有助于了解高原鼠兔干扰下植物多样性影响高寒草甸生态系统功能的途径。

基于Sentinel-2数据的草地植物功能多样性遥感反演及其与生产力的关系

生物多样性与生态系统功能的关系是当前生态学研究的焦点和难点。植物功能多样性是影响生态系统功能的重要指标,开展植物功能多样性的研究对了解生物多样性与生态系统功能之间的关系有着重要意义。传统的草地植物功能多样性研究多以实地调查为主,不仅费时费力,而且由于受到时空的限制,很难拓展到大尺度的研究中。遥感技术的发展为评估草地功能多样性提供了一种经济、有效的手段。该研究选取内蒙古自治区锡林郭勒盟乌拉盖管理区草甸草原为研究区,利用Sentinel-2卫星影像和野外实测数据,选取了波段及植被指数等46个特征变量,探讨了逐步回归、偏最小二乘法(PLSR)和随机森林(RFR)等3种不同方法对草地植物功能丰富度(FRic)、功能均匀度(FEve)和功能离散度(FDiv)的反演精度,并基于PLSR反演草地地上生物量,进一步分析了研究区功能多样性与生产力的关系。研究结果表明:(1)波段B11、优化型土壤调节植被指数(OSAVI)、水波段指数(WBI)对FRic解释度最高;波段B6、B10、B12、类胡萝卜素反射指数1(CRI1)、双峰光学指数(D)、归一化差值指数45(NDI45)等6个特征变量对FEve解释度最高;波段B5、B9、B10、B11、加权差分植被指数(WDVI)、凸包面积等对FDiv解释度最高;(2)基于十折重复交叉验证,利用逐步回归估算的FRic和FEve反演精度远高于其他两种回归方法,R^(2)分别为0.52和0.44;而利用PLSR方法估算的FDiv反演精度最高(R^(2)=0.61);(3)群落地上生物量反演精度为R^(2)=0.61;FRic与地上生产力的关系最好(R^(2)=0.40),其次为FDiv(R^(2)=0.28)和FEve(R^(2)=0.27)。研究发现,基于Sentinel-2卫星影像能较好地反演草地功能多样性和生产力,为下一步能在大尺度上进行草地功能多样性估算及其与生产力关系研究提供了参考和依据。

园林植物群落多样性及景观形成的相关性研究

本研究探讨了园林植物群落多样性与景观形成的关系,并分析了其对实践和管理的意义。研究发现,植物群落多样性对景观的形态、层次和可持续性具有重要影响。它能增加景观的物种组成和丰富度,创造多样化的景观体验;同时,植物的功能多样性对景观的结构和生态系统服务产生影响。因此,在园林规划和管理中,应充分考虑植物群落多样性,保持其多样性并选择具有不同生态系统功能的植物,以创造更美观、生态友好和可持续的园林景观。

城市景观系统固碳设计策略

随着气候变化与全球变暖,减碳已成为全球普遍关注的话题。城市景观将有望通过景观生态系统作为新的碳汇手段,融合自然景观与城市建成景观为碳中和做出贡献。然而要提高景观碳汇效果不能单纯依靠植物,而是要综合考虑植物群落对于土壤固碳、蓝碳系统固碳、乃至整个景观生态系统碳汇的整体效益。但是如何在具体的设计项目中提升景观碳汇效率仍缺乏一个可操作的整体思路及设计模式。为此,该文在对景观碳汇发展历程、机制进行梳理,结合实证研究提出综合性景观系统碳汇的设计策略,以期为实现碳中和目标提供新思路与可操作方法。

The Influence of Plant Diversity and Functional Composition on Ecosystem Stability of Four Stipa Communities in the Inner Mongolia Plateau

The main purpose of this study was to examine the effects of plant species diversity and functional composition (the identity of the plant functional groups) on ecosystem stability of Stipa, communities in the Inner Mongolia Plateau. The research work was based on a 12-year study (from 1984 to 1995) of species abundance, diversity, and primary productivity of four Stipa communities, i.e. S. baicalensis Roshev., S. grandis P. Smirn., S, krylovii Roshev., and S. klemenzii Roshev. respectively. The Shnnon-Wiener index was used as a measurement of plant diversity, while functional composition was used to differentiate the functional groups that were included in the communities. The plant species of four Stipa communities were classified into functional groups based on the differences in life forms and ecological groups, which influence their performance in resource requirements, seasonality of growth, tolerance to water stress, and life history. Plant species were classified into five functional groups based on their differences in life form, shrubs and half shrubs, perennial bunch grasses, perennial rhizome grasses, forbs, annuals and biennials. Based on their differences in water requirement these species were classified into four functional groups: xerads, intermediate xerads, intermediate mesophytes, and mesophytes. The results showed: 1) Plant species diversity stabilized ecosystem processes. Shannon-Wiener index were 2.401 4, 2.172 0, 1.624 8, 0.354 3 from S. baicalensis community to S. grandis, S. krylovii and S. klemenzii community, respectively. The dynamics of the aboveground net primary productivity (ANPP) for a 12-year's period showed a reverse pattern, the coefficients of variation of the four communities were 21.94%, 20.63%, 29.21% and 39.72% respectively. 2) The Life form functional group component of diversity was a greater determinant of the ecosystem processes than the species component of diversity. The effects of perennial bunch grasses, perennial rhizome grasses and forbs on community stability were highly significant. 3) The ecological group component of diversity was also a great determinant of the ecosystem processes. The effects of xerads, intermediate xerads, and mesophytes on community stability were also very strong.

Research on Stoichiometry of Early-spring Herbs Functional Group in the Subtropical Artificial Wetland

[Objective]The aim was to carry out stoichiometry on the early-spring herbs functional group in subtropical artificial wetland.[Method]UV-Vis spectrophotometer was used for the determination of nitrate-nitrogen,ammonium nitrogen and phosphorus concentrations.Potassium persulfate absorptiometry was used for the measurement of total N content,while the flame photometer was used to detect the potassium and sodium concentration in plants.All the nutrient determination of plant samples were repeated for four times.[Result]The four nutrient concentrations in almost all samples were in the normal range of natural plant nutrition concentrations;in early-spring herbs functional groups,different species showed diversity on the nutrient concentrations;plant height had no significant effect on the nutrient concentrations in plants;the nutrient concentrations of non-grass group plants were higher than that of grass group plants;the nutrient concentrations of the annual herb were higher than that of perennial herbs.[Conclusion]The study had provided basis for the understanding of the effects of changes in nutritional conditions on species diversity,community structure and succession of the system.

青藏高原高寒草地土壤微生物群落及影响因子

青藏高原是我国生态安全的重要屏障,但目前青藏高原上大尺度上的微生物地理学研究还很缺乏.因此,采用高通量测序技术,在跨越2121 km的尺度上针对高寒草地不同生态系统类型研究了土壤原核生物(细菌和古菌)微生物量、多样性和群落组成的分布格局,及与气候、植物和土壤因子的关系.在高寒草甸、高寒草原、高寒灌丛和高寒荒漠中,高寒荒漠具有最低的微生物多样性,而高寒草甸具有最高的微生物量碳.高寒草地土壤微生物的多样性与大气温度而非降水显著相关,说明其在高寒条件下可能受温度而非水分控制.微生物多样性随耦合了水、热要素的干旱指数的增加而降低,解释量比单一要素更高.此外,植物功能群多样性与微生物多样性有显著的正相关关系,解释量比植物物种多样性更高.结构方程模型显示,干旱指数和年均温通过影响植物功能群多样性和地上生物量而改变土壤表层的碳氮比,从而直接或间接影响到微生物多样性.与多样性不同,土壤微生物量碳与可溶性有机碳、氨态氮、速效磷及碳氮比等土壤营养指标和植物地上生物量具有显著的相关性.这些结果意味着微生物多样性和微生物量可能有着不同的控制因子;随着未来青藏高原的'暖湿化',干旱指数的降低可能提高土壤微生物的多样性.

Contribution of plant traits to the explanation of temporal variations in carbon and water fluxes in semiarid grassland patches

Aims Accurate prediction of spatiotemporal variations in carbon and water fluxes of heterogeneous landscape is critical to comprehensively address the effects of climate change and vegetation dynamics on landscape and regional carbon and water cycling.Methods A field study was conducted to characterize the seasonal variations in gas fluxes and explore their relationships with abiotic and biotic factors in a small grassland landscape.Daytime carbon and water fluxes including net ecosystem exchange,gross ecosystem productivity,ecosystem respiration and evapotranspiration(ET)were measured for three types of grassland patches over a growing season using the closed chamber method.The key plant trait variables were measured,based on which community weighted mean(CWM)and functional variance(FDvar)were calculated.Important Findings The results showed that the temporal variations in the carbon and water fluxes were regulated by meteorological,soil and community functional variables.Inclusion of the CWM and FDvar of plant trait measures greatly improved the degree of explanation of the predict models.Specific leaf area and leafδ^(13)C content(Lδ^(13)C)were the most important trait variables in affecting the variations of the gas fluxes.CWMs indices had greater importance than FDvar indices in predicting the variation of the C fluxes but FDvar indices were more important for ET than C fluxes.Our findings demonstrated that mass ratio hypothesis and the complementary effects hypothesis are not mutually exclusive but have different relative importance for different ecosystem processes.Community functional traits played important roles in predicting the spatiotemporal variations of carbon and water fluxes in semiarid grassland.

A buried Neolithic paddy soil reveals loss of microbial functional diversity after modern rice cultivation

It has been documented that human activities are causing the rapid loss of taxonomic, phylogenetic, genetic and functional diversity in soils. However, it remains unclear how modern intensive rice cultivation impacts the soil microbiome and its functionality. Here we examined the microbial composition and function differences between a buried Neolithic paddy soil and an adjacent, currently-cultivated paddy soil using high throughput metagenomics technologies. Our results showed that the currently cultivated soil contained about 10-fold more microbial biomass than the buried one. Analyses based on both 16S rRNA genes and functional gene array showed that the currently cultivated soil had significantly higher phylogenetic diversity, but less functional diversity than the buried Neolithic one. The community structures were significantly different between modern and ancient soils, with functional structure shifting towards accelerated organic carbon （C） degradation and nitrogen （N） transfor- mation in the modem soils. This study implies that, modern intensive rice cultivation has substantially altered soil microbial functional structure, leading to functional homogenization and the promotion of soil ecological functions related to the acceleration of nutrient cycling which is necessary for high crop yields.

Grazing effects on the relationship between plant functional diversity and soil carbon sequestration regulated by livestock species

Grazing exerts a profound influence on both the plant diversity and productivity of grasslands,while simultaneously exerting a significant impact on regulating grassland soil carbon sequestration.Moreover,besides altering the taxonomic diversity of plant communities,grazing can also affect their diversity of functional traits.However,we still poorly understand how grazing modifies the relationship between plant functional diversity(FD)and soil carbon sequestration in grassland ecosystems.Here,we conducted a grazing manipulation experiment to investigate the effects of different grazing regimes(no grazing,sheep grazing(SG)and cattle grazing(CG))on the relationships between plant FD and soil carbon sequestration in meadow and desert steppe.Our findings showed that different livestock species changed the relationships between plant FD and soil organic carbon(SOC)in the meadow steppe.SG decoupled the originally positive relationship between FD and SOC,whereas CG changed the relationship from positive to negative.In the desert steppe,both SG and CG strengthened the positive relationship between FD and SOC.Our study illuminates the considerable impact of livestock species on the intricate mechanisms of soil carbon sequestration,primarily mediated through the modulation of various measures of functional trait diversity.In ungrazed meadows and grazed deserts,maintaining high plant FD is conducive to soil carbon sequestration,whereas in grazed meadows and ungrazed deserts,this relationship may disappear or even reverse.By measuring the traits and controlling the grazing activities,we can accurately predict the carbon sequestration potential in grassland ecosystems.