西藏草地植物功能性状与多项生态系统服务关系

针对植被功能性状与生态系统服务功能之间的相互关系,构建了西藏草地株高和可食性两种功能性状的9项指标,并基于土壤和植物采样,分析了9项植物功能性状指标和5项生态系统服务指标间的相关性,探讨了4种机制(Mass ratio,Selection,Niche complementarity及Insurance)在西藏草地的适用性。结果表明,9项功能性状指标中,株高Rao和可食种与所有种株高CWM比分别与土壤有机碳、土壤全氮和土壤含水率3项生态系统服务指标呈显著负相关及显著正相关。说明群落植被对光能竞争的互补性及可食性状植株在群落中的光能资源相对竞争力,与土壤固碳、肥力供给及水源涵养有显著相关关系。而群落可食种、优势种、优势种与次优势种对光能资源竞争力水平,可食植株多样性、可食植株在群落中的优势度及其光能资源竞争力均值,对草地生态系统服务无显著影响。西藏草地植物功能性状对多项生态系统服务的影响机制从光能资源竞争角度更符合Niche complementarity和Insurance理论,而从可食功能性状角度更符合Mass ratio和Selection理论。     

A landscape‐scale assessment of the relationship between grassland functioning,community diversity,and functional traits

Livestock farmers rely on a high and stable grassland productivity for fodder production to sustain their livelihoods. Future drought events related to climate change, however, threaten grassland functionality in many regions across the globe. The introduction of sustainable grassland management could buffer these negative effects. According to the biodiversity–productivity hypothesis, productivity positively associates with local biodiversity. The biodiversity–insurance hypothesis states that higher biodiversity enhances the temporal stability of productivity. To date, these hypotheses have mostly been tested through experimental studies under restricted environmental conditions, hereby neglecting climatic variations at a landscape‐scale. Here, we provide a landscape‐scale assessment of the contribution of species richness, functional composition, temperature, and precipitation on grassland productivity. We found that the variation in grassland productivity during the growing season was best explained by functional trait composition. The community mean of plant preference for nutrients explained 24.8% of the variation in productivity and the community mean of specific leaf area explained 18.6%, while species richness explained only 2.4%. Temperature and precipitation explained an additional 22.1% of the variation in productivity. Our results indicate that functional trait composition is an important predictor of landscape‐scale grassland productivity.     

中国东南部农区蚂蚁物种多样性研究

为探清我国东南部农区内蚂蚁物种多样性,本研究共设置86个采样单元格,每个单元格内选择农田、草地和人工林3种生境,每种生境设置3个重复样地,每个重复生境设置5个1 m2的重复采样样方,用吸虫器采集样方内的地表蚂蚁。结果表明：在我国东南部农区共采集鉴定地表蚂蚁30 077头,隶属于7亚科49属155种;长江中下游地区共采集蚂蚁5亚科34属93种,其中优势种3个,常见种9个,稀有种81个;华南地区采集蚂蚁7亚科42属124种,其中优势种2个,常见种11个,稀有种111个。红火蚁Solenopsis invicta Buren是华南地区个体数目最多的物种,占个体总数的39.40%;物种数目、个体密度、多样性指数和优势度指数均表现为华南地区＞长江中下游地区;不同生境内蚂蚁群落的物种数目、多样性指数和均匀度指数表现为人工林＞草地＞农田,个体密度和优势度指数人工林生境最低;两个地区3种生境蚂蚁群落间相似性系数0.2437~0.6581,处于极不相似至中等相似水平。结果表明,我国东南部农区蚂蚁种类丰富,在农区的生物多样性保护中具有重要价值;红火蚁在华南地区入侵扩散严重,亟需治理;农区内不同土地利用方式造成的生境差异影响蚂蚁群落的物种组成和多样性;不同区域、不同生境的蚂蚁群落间差异明显。     

Using functional traits to predict grassland ecosystem change: a mathematical test of the response-and-effect trait approach

The role of plant community structure and plant functional traits for above- and belowground carbon (C) fluxes was studied for 2 years in a mesocosm experiment with grassland monoliths, using continuous gas exchange measurements and soil analyses. Here we test the response-and-effect trait hypothesis, by applying a mathematical framework used to predict changes in C fluxes after a change in disturbance through the community response ( R ) and effect ( E ) traits. Monoliths were extracted from two contrasted long-term field treatments (high vs. low grazing disturbance) and exposed to both low and high (simulated grazing) disturbance during a 2 years experiment. Carbon dioxide exchanges were measured continuously in an open flow system. Net ecosystem productivity and ecosystem C balance were positively correlated at low disturbance with plant species richness. Aboveground net primary productivity (ANPP) and soil C sequestration were, however, unrelated to these variables. Community aggregated leaf (specific leaf area, leaf dry-matter content) and root and rhizome (specific length, tissue density, diameter) traits responded ( R ) significantly to changes in disturbance, indicating an increased dominance of conservative plant growth strategies at low compared with high disturbance. Applying the mathematical framework, ANPP was predicted by distribution of leaf traits within the community (functional divergence), while mean root and rhizome traits had significant effects ( E ) on soil C sequestration, irrespective of the experimental disturbance and of the year. According to highly significant linear regression models, between 6% and 61% of the transient changes in soil C sequestration resulted from community root and rhizome (response-and-effect) traits after a change in disturbance.     

基于功能性状的生态系统服务研究框架

功能性状通过影响生态系统的属性和过程及其维持来影响生态系统服务。功能多样性-生态系统功能关系的研究有助于深入探讨生态系统服务形成机制, 也为生态系统服务研究提供了一个切入点。该文对目前的功能性状和生态系统服务研究框架进行了介绍, 回顾了功能多样性-生态系统功能关系的研究现状, 总结了目前功能性状在生态系统服务研究中的应用, 提出了基于功能性状的生态系统服务研究框架。在这个研究框架中, 首先选取对生态系统功能影响显著的非生物因子和功能多样性指数, 然后量化非生物因子和功能多样性与生态系统功能, 以及生态系统功能-生态系统服务之间的关系, 进而构建功能多样性与生态系统服务的数量关系。与此同时, 利用群落构建理论和物种共存机制分析功能多样性-生态系统功能变化的机制联系, 以研究生态系统服务形成和变化机制, 为生态系统服务管理决策提供科学依据。     

Greater variation in boreal plant community composition and community-level traits at local- than regional-scale

Questions

Rapid climate change in northern latitudes is expected to influence plant functional traits of the whole community (community-level traits) through species compositional changes and/or trait plasticity, limiting our ability to anticipate climate warming impacts on northern plant communities. We explored differences in plant community composition and community-level traits within and among four boreal peatland sites and determined whether intra- or interspecific variation drives community-level traits.

Location

Boreal biome of western North America.

Methods

We collected plant community composition and functional trait data along dominant topoedaphic and/or hydrologic gradients at four peatland sites spanning the latitudinal extent of the boreal biome of western North America. We characterized variability in community composition and community-level traits of understorey vascular and moss species both within (local-scale) and among sites (regional-scale).

Results

Against expectations, community-level traits of vascular plant and moss species were generally consistent among sites. Furthermore, interspecific variation was more important in explaining community-level trait variation than intraspecific variation. Within-site variation in both community-level traits and community composition was greater than among-site variation, suggesting that local environmental gradients (canopy density, organic layer thickness, etc.) may be more influential in determining plant community processes than regional-scale gradients.

Conclusions

Given the importance of interspecific variation to within-site shifts in community-level traits and greater variation of community composition within than among sites, we conclude that climate-induced shifts in understorey community composition may not have a strong influence on community-level traits in boreal peatlands unless local-scale environmental gradients are substantially altered.     

青藏高原高寒草地群落叶片功能性状对降水的非线性响应

群落叶片功能性状受到外界环境和自身发育的共同影响,其响应特征和过程的研究有助于了解环境胁迫下植物的适应策略,以应对全球变化下的生物多样性和生态系统功能丧失。通过对青藏高原高寒草地115个样点的调查取样,测定群落叶片碳、氮和磷含量(LC、LN和LP)及干物质量(LDMC)4种能够反映植物生存策略的叶片功能性状,以物种相对多度为基础计算群落加权平均值(CWM)。结合降水量、气温和土壤因子,探索高寒草地群落叶片功能性状响应机制。结果表明：(1)降水量对群落叶片功能性状影响显著(P<0.01),而温度对群落叶片功能性状影响不显著(P>0.05);(2)土壤全氮和有机碳对CWM＿LC、CWM＿LN、CWM＿LP和CWM＿LDMC影响显著(P<0.01),且除CWM＿LDMC外,其余性状均表现为非线性响应,呈先下降后上升趋势;(3)土壤含水量和容重对CWM＿LC、CWM＿LN、CWM＿LP和CWM＿LDMC影响显著(P<0.05),且土壤含水量对各性状的影响为非线性,呈先下降后上升趋势。该研究说明水分是青藏高原高寒草地群落叶片功能性状的主要影响因子,高寒草地对恶劣环境的适应...     

蚂蚁群落与栖境关系研究进展及新趋势

生物群落与栖境的关系是生态学研究的核心之一,蚂蚁群落由于在陆地生态系统中的生物量、分布以及具备的生态功能的重要性,是研究这种关系的理想对象。在查阅大量文献的基础上,简述了蚂蚁物种多样性与栖境关系研究现状。介绍了蚂蚁功能群划分以及在不同尺度上与栖境关系的应用研究,评述了功能群应用的限制。阐明了功能特征的定义以及基于形态特征和营养级方面的蚂蚁群落功能特征与栖境的研究,并对功能特征的研究趋势进行了展望。     

Using root traits to understand temporal changes in biodiversity effects in grassland mixtures

Biodiversity–ecosystem functioning (BEF) studies typically show that species richness enhances community biomass, but the underlying mechanisms remain debated. Here, we combine metrics from BEF research that distinguish the contribution of dominant species (selection effects, SE) from those due to positive interactions such as resource partitioning (complementarity effects, CE) with a functional trait approach in an attempt to reveal the functional characteristics of species that drive community biomass in species mixtures. In a biodiversity experiment with 16 plant species in monocultures, 4‐species and 16‐species mixtures, we used aboveground biomass to determine the relative contributions of CE and SE to biomass production in mixtures in the second, dry year of the experiment. We also measured root traits (specific root length, root length density, root tissue density and the deep root fraction) of each species in monocultures and linked the calculated community weighted mean (CWM) trait values and trait diversity of mixtures to CE and SE. In the second year of the experiment, community biomass, CE and SE increased compared to the first year. The contribution of SE to this positive effect was greater than that of CE. The increased contribution of SE was associated with root traits: SE increased most in communities with high abundance of species with deep, thick and dense roots. In contrast, changes in CE were not related to trait diversity or CWM trait values. Together, these results suggest that increased positive effects of species richness on community biomass in a dry year were mainly driven by increased dominance of deep‐rooting species, supporting the insurance hypothesis of biodiversity. Positive CE indicates that other positive interactions did occur, but we could not find evidence that belowground resource partitioning or facilitation via root trait diversity was important for community productivity in our biodiversity experiment.     

Exploring the community assembly of subalpine meadow communities based on functional traits and community phylogeny

Aims The community assembly has been a prominent issue in community ecology. This work was intended to explore the mechanisms of the species coexistence and biodiversity in communities. Our objective was to explore the mechanisms of community assembly in subalpine meadow plant communities along slope gradients in Gannan Tibetan Autonomous Prefecture, Gansu Province, Northwest China.Methods We selected five slope-oriented plots to construct a super-tree representing the species pool. We surveyed the leaf functional traits and soil environmental factors in different slopes. Then we tested the phylogenetic signal of leaf dry matter content (LDMC), specific leaf area (SLA), leaf nitrogen content (LNC) and leaf phosphorus content (LPC).Important findings The changes of slope aspect had significant influence on soil water content (SWC) and soil nutrient content. Most of the plants leaf functional traits had significant difference along different slope aspects. The LDMC was higher in south and southwest slope than north slope, while SLA, LNC and LPC were relatively high in north and northwest slope. The LPC showed feeble phylogenetic signal, while LDMC, SLA, LNC did not have a significant phylogenetic signal. With changes in the slope aspect from south to north, community phylogenetic structure shifted from over-dispersion to clustered dispersion. In south and southwest slope, habitat filtering was the driving force for community assembly. Interspecific competition was the main driving factor for community assembly in north and northwest slope aspects. But in west slope, two indices showed contrary consequence. This means the process of community assembly in west slope was more complicated and its phylogenetic index may be the result of several mechanisms working together.     

Microbial community composition and functional diversity in the rhizosphere of maize

This study investigates the small-scale stratification of bacterial community composition and functional diversity in the rhizosphere of maize. Maize seedlings were grown in a microcosm with a horizontal mesh (53 M) creating a planar root mat and rhizosphere soil. An unplanted microcosm served as control. Thin slices of soil were cut at different distances from the mesh surface (0.2–5.0 mm) and analysed for bacterial community composition by PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) of 16S rDNA and tested for activities of different enzymes involved in C, N, P and S cycling. Bacterial community composition and microbial functional diversity were affected by the presence of the maize roots. The bacterial composition showed a clear gradient up to 2.2 mm from the root surface, while no such gradient was observed in the unplanted pot. Invertase and phosphatase activities were higher in the close vicinity of maize roots (0.2–0.8 mm), whereas xylanase activity was unaffected. This study shows that the changes in bacterial community composition and functional diversity induced by roots may extend several millimetres into the soil.     

Environmental predictability of taxonomic and functional community composition in high‐latitude streams

相似文献   

Permafrost condition determines plant community composition and community‐level foliar functional traits in a boreal peatland

Boreal peatlands are critical ecosystems globally because they house 30%–40% of terrestrial carbon (C), much of which is stored in permafrost soil vulnerable to climate warming‐induced thaw. Permafrost thaw leads to thickening of the active (seasonally thawed) layer and alters nutrient and light availability. These physical changes may influence community‐level plant functional traits through intraspecific trait variation and/or species turnover. As permafrost thaw is expected to cause an efflux of carbon dioxide (CO₂) and methane (CH₄) from the soil to the atmosphere, it is important to understand thaw‐induced changes in plant community productivity to evaluate whether these changes may offset some of the anticipated increases in C emissions. To this end, we collected vascular plant community composition and foliar functional trait data along gradients in aboveground tree biomass and active layer thickness (ALT) in a rapidly thawing boreal peatland, with the expectation that changes in above‐ and belowground conditions are indicative of altered resource availability. We aimed to determine whether community‐level traits vary across these gradients, and whether these changes are dominated by intraspecific trait variation, species turnover, or both. Our results highlight that variability in community‐level traits was largely attributable to species turnover and that both community composition and traits were predominantly driven by ALT. Specifically, thicker active layers associated with permafrost‐free peatlands (i.e., bogs and fens) shifted community composition from slower‐growing evergreen shrubs to faster‐growing graminoids and forbs with a corresponding shift toward more productive trait values. The results from this rapidly thawing peatland suggest that continued warming‐induced permafrost thaw and thermokarst development alter plant community composition and community‐level traits and thus ecosystem productivity. Increased productivity may help to mitigate anticipated CO₂ efflux from thawing permafrost, at least in the short term, though this response may be swamped by increase CH₄ release.     

生态学的多样性指数:功能与系统发育

生物多样性是生态学的核心问题。传统的多样性指数仅包含物种数和相对多度的信息,这类基于分类学的多样性指数并不能很好地帮助理解群落构建和生态系统功能。不同物种对群落构建和生态系统功能所起到的作用类型和贡献也不完全相同,且物种在生态过程中的作用和贡献往往与性状密切相关,因此功能多样性已经成为反映物种群落构建、干扰以及环境因素对群落影响的重要指标。同时,由于亲缘关系相近的物种往往具有相似的性状,系统发育多样性也可以作为功能多样性的一个替代。功能多样性和系统发育多样性各自具有优缺点,但二者均比分类多样性更能揭示群落和生态系统的构建、维持与功能。     

Ecosystem services provided by semi-natural and intensified grasslands: Synergies,trade-offs and linkages to plant traits and functional richness

Question

Semi-natural grasslands (SNG) are important for maintaining biodiversity and ecological processes in farmland. Current pasture-based livestock production mainly occurs on intensified grasslands (IG) that have been agronomically improved. Although it is documented that SNG and IG differ in terms of plant diversity, their ability to provide ecosystem services (ES) in farmland is less explored. Here, we review the role of SNG and IG in delivering ES, illustrate their trade-offs and synergies, and examine how ES can be assessed by using plant traits and functional richness.

Results

We found that SNG generate a wider range of ES than IG. Trade-offs exist between ES that appear more pronounced in IG between high biomass production and other ES. SNG are good in providing habitat for biodiversity, supporting pollination and cultural services. SNG also have a significantly wider range of plant functional traits and a higher functional richness, suggesting that the potential to supply ES in SNG is partly driven by higher number of species and their functional diversity.

Conclusion

Clearer trade-offs were found in IG compared with SNG, supported both by the literature and the functional richness. This suggests that functional knowledge could be a good complement to understand the mechanisms behind ES generation and could help with tailoring grassland management to sustain biodiversity, ecological functions and ES. Although both IG and SNG are likely needed for the long-term sustainability of food production, both could aim for a more balanced generation of ES, increasing biodiversity and functional redundancy at the landscape scale.     

Functional traits composition predict macrophytes community productivity along a water depth gradient in a freshwater lake

Functional trait composition of plant communities has been proposed as a helpful key for understanding the mechanisms of biodiversity effects on ecosystem functioning. In this study, we applied a step‐wise modeling procedure to test the relative effects of taxonomic diversity, functional identity, and functional diversity on macrophytes community productivity along water depth gradient. We sampled 42 plots and 1513 individual plants and measured 16 functional traits and abundance of 17 macrophyte species. Results showed that there was a significant decrease in taxonomic diversity, functional identity (i.e., stem dry mass content, leaf [C] and leaf [N]), and functional diversity (i.e., floating leaf, mean Julian flowering date and rooting depth) with increasing water depth. For the multiple‐trait functional diversity (FD) indices, functional richness decreased, while functional divergence increased with water depth gradient. Macrophyte community productivity was strongly determined by functional trait composition within community, but not significantly affected by taxonomic diversity. Community‐weighted means (CWM) showed a two times higher explanatory power relative to FD indices in determining variations in community productivity. For nine of sixteen traits, CWM and FD showed significant correlations with community productivity, although the strength and direction of those relations depended on selected trait. Furthermore, functional composition in a community affected productivity through either additive or opposite effects of CWM and FD, depending on the particular traits being considered. Our results suggested both mechanisms of mass ratio and niche complementarity can operate simultaneously on variations in community productivity, and considering both CWM and FD would lead to a more profound understanding of traits–productivity relationships.     

A practical guide to measuring functional indicators and traits in biocrusts

Biocrusts are multifunctional communities that are increasingly being used to restore degraded or damaged ecosystems. Concurrently, restoration science is shifting away from the use of purely structural metrics, such as relative abundance, to more functional approaches. Although biocrust restoration technology is advancing, there is a lack of readily available information on how to monitor biocrust functioning and set appropriate restoration goals. We therefore compiled a selection of 22 functional indicators that can be used to monitor biocrust functions, such as CO₂ exchange as an indicator of productivity or soil aggregate stability as a proxy for erosion resistance. We describe the functional importance of each indicator and the available protocols with which it may be measured. The majority of indicators can be measured as a functional trait of species by using patches of biocrust or cultures that contain only one species. Practitioners wishing to track the multifunctionality of an entire biocrust community would be advised to choose one indicator from each broad functional group (erosion resistance, nutrient accumulation, productivity, energy balance, hydrology), whereas a targeted approach would be more appropriate for projects with a key function of interest. Because predisturbance data are rarely available for biocrust functions, restoration goals can be based on a closely analogous site, literature values, or an expert elicitation process. Finally, we advocate for the establishment of a global trait database for biocrusts, which would reduce the damage resulting from repeated sampling, and provide a wealth of future research opportunities.