The ecology of Maesopsis eminii Engl. in tropical Africa

Maesopsis eminii is referred to as one of the most widely distributed African tree species. However, its occurrence in Africa has never been mapped and little is known as to how this species can sustain in different environments. To gain insight into Maesopsis’ ecology, we (i) made a synthesis of its functional trait data from the literature, (ii) investigated phenological patterns using data on four M. eminii trees from Yangambi, DR Congo, (iii) assessed an empirical provenance trial from Uganda on 600 Maesopsis trees and (iv) synthesized geo‐referenced point location maps of Maesopsis entailing WorldClim precipitation and temperature and FAO soils, rainfall and ecological zones for Africa. We found M. eminii to straddle the equator equidistantly in terms of latitude (10.97°N and 10.98°S) covering five forest types where twenty soil types and variable rainfall regimes support complex plant biodiversity. Maesopsis eminii was, however, largely concentrated in the tropical rainforest ecosystem which contains fertile Orthic Ferralsol soils. More than 97% of the point locations were found where annual precipitation was >1000 mm, and 82% occurred where average annual temperature was 22–28°C. Its functional traits, phenology and provenance trial findings explained its occurrence in Africa.     

Plant species diversity is correlated with climatic factors differently at the community and the functional group levels: A case study of desert steppe in Inner Mongolia,China

In the desert steppe of Inner Mongolia, mean annual precipitation was found to be the dominant factor that correlated positively with species richness at the community level and for the perennial forb functional group. Shrub and semi-shrub functional group exhibited positive correlation with mean temperature of the coldest month.     

The spatial frequency of climatic conditions affects niche composition and functional diversity of species assemblages: the case of Angiosperms

Climatic conditions vary in spatial frequency globally. Spatially rare climatic conditions provide fewer suitable environments than common ones and should impose constraints on the types of species present locally and regionally. We used data on 467 North American angiosperms to test the effects of the spatial frequency of climatic conditions on ecological niche specialisation and functional diversity. We predicted that rare climates should favour generalist species that are able to inhabit a broader range of climatic conditions. Our results show that climate frequency filters species that differ in niche breadths and rare environments host species combinations with greater functional diversity. The proposed analytical approaches and hypotheses can be adapted to investigate different aspects of ecological assemblies and their biodiversity. We discuss different mechanisms regarding how spatial frequency of environments can affect niche composition and functional diversity. These should be useful while developing theoretical frameworks for generating a deeper understanding of its underpinnings.     

Climate change threats to the global functional diversity of freshwater fish

Climate change impacts on freshwater ecosystems and freshwater biodiversity show strong spatial variability, highlighting the importance of a global perspective. While previous studies on biodiversity mostly focused on species richness, functional diversity, which is a better predictor of ecosystem functioning, has received much less attention. This study aims to comprehensively assess climate change threats to the functional diversity of freshwater fish across the world, considering three complementary metrics—functional richness, evenness and divergence. We built on existing spatially explicit projections of geographical ranges for 11,425 riverine fish species as affected by changes in streamflow and water temperature extremes at four warming levels (1.5°C, 2.0°C, 3.2°C and 4.5°C). To estimate functional diversity, we considered the following four continuous, morphological and physiological traits: relative head length, relative body depth, trophic level and relative growth rate. Together, these traits cover five ecological functions. We treated missing trait values in two different ways: we either removed species with missing trait values or imputed them. Depending on the warming level, 6%–25% of the locations globally face a complete loss of functional diversity when assuming no dispersal (6%–17% when assuming maximal dispersal), with hotspots in the Amazon and Paraná River basins. The three facets of functional diversity do not always follow the same pattern. Sometimes, functional richness is not yet affected despite species loss, while functional evenness and divergence are already reducing. Other times, functional richness reduces, while functional evenness and/or divergence increase instead. The contrasting patterns of the three facets of functional diversity show their complementarity among each other and their added value compared to species richness. With increasing climate change, impacts on freshwater communities accelerate, making early mitigation critically important.     

植物功能性状对全球气候变化的指示作用研究进展

以大气CO2浓度升高、大气温度升高、干旱胁迫加剧及紫外辐射增强为特征的全球变化对陆地生态系统产生巨大影响,植物作为陆地生态系统的重要组成部分,其功能性状对全球变化的指示作用为探寻全球变化规律、减缓气候变化提供了科学依据。该文主要综述了植物生理功能性状改变(形态变化、气孔调节、光合结构及光合途径改变和植物光合、呼吸速率及水分生理变化等)和物候功能性状改变对全球变化的指示作用,以及植物群落物种丰富度或数量增加等群落特征变化对全球气候变暖的指示作用。最后指出,完善植物功能性状指标和建立从植物个体、群落到生态系统功能的网络指示系统是今后植物功能性状指示研究的发展方向。     

Geographical variation and environmental correlates of functional trait distributions in palms (Arecaceae) across the New World

Functional traits play a key role in driving biodiversity effects on ecosystem functioning. Here, we examine the geographical distributions of three key functional traits in New World palms (Arecaceae), an ecologically important plant group, and their relationships with current climate, soil and glacial–interglacial climate change. We combined range maps for the New World (N = 541 palm species) with data on traits (leaf size, stem height and fruit size), representing the leaf–height–seed plant strategy scheme of Westoby, to estimate median trait values for palm species assemblages in 110 × 110‐km grid cells. Spatial and non‐spatial multi‐predictor regressions were used with the Akaike Information Criterion to identify minimum adequate models. Present‐day seasonality in temperature and precipitation played a major role in explaining geographical variation of all traits. Mean annual temperature and annual precipitation were additionally important for median leaf size. Glacial–interglacial temperature change was the most important predictor for median fruit size. Large‐scale soil gradients played only a minor role overall. These results suggest that current climate (larger median trait values with increasing seasonality) and glacial–interglacial temperature change (larger median fruit size with increasing Quaternary temperature anomaly) are important drivers for functional trait distributions of New World palms. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 602–617.     

Tracking lags in historical plant species’ shifts in relation to regional climate change

Can species shift their distributions fast enough to track changes in climate? We used abundance data from the 1950s and the 2000s in Wisconsin to measure shifts in the distribution and abundance of 78 forest‐understory plant species over the last half‐century and compare these shifts to changes in climate. We estimated temporal shifts in the geographic distribution of each species using vectors to connect abundance‐weighted centroids from the 1950s and 2000s. These shifts in distribution reflect colonization, extirpation, and changes in abundance within sites, separately quantified here. We then applied climate analog analyses to compute vectors representing the climate change that each species experienced. Species shifted mostly to the northwest (mean: 49 ± 29 km) primarily reflecting processes of colonization and changes in local abundance. Analog climates for these species shifted even further to the northwest, however, exceeding species’ shifts by an average of 90 ± 40 km. Most species thus failed to match recent rates of climate change. These lags decline in species that have colonized more sites and those with broader site occupancy, larger seed mass, and higher habitat fidelity. Thus, species’ traits appear to affect their responses to climate change, but relationships are weak. As climate change accelerates, these lags will likely increase, potentially threatening the persistence of species lacking the capacity to disperse to new sites or locally adapt. However, species with greater lags have not yet declined more in abundance. The extent of these threats will likely depend on how other drivers of ecological change and interactions among species affect their responses to climate change.     

Invertebrate assemblages of pools in arid‐land streams have high functional redundancy and are resistant to severe drying

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浙江古田山亚热带常绿阔叶林开花物候:气候因素、系统发育关系和功能性状的影响

植物的开花物候受气候因素、植物系统发育关系和功能性状的影响。然而当前植物开花物候研究中未见同时考虑这3个因素的报道。为了解它们相互之间的影响, 本研究利用中国东部地区浙江省古田山国家级自然保护区亚热带常绿阔叶林24 ha大样地(GTS; 118°03′50′′-118°11′12.2′′ E, 29°10′19′′-29°17′41′′ N)设置的130个种子雨收集器5年的开花数据检验这3个因素对开花的影响。结果表明, 古田山植物的开花高峰期集中在5月, 群落开花格局明显受温度和降雨的影响。利用植物DNA条形码数据研究发现, 植物间系统发育关系对古田山植物开花时间有显著影响, 亲缘关系近的物种开花时间更相近。植物的平均开花时间受最大树高的影响, 但不受传粉方式、花色、种子质量和扩散方式的影响。该研究结果说明气候因素、植物系统发育关系和功能性状都可能影响植物开花物候格局, 同时考虑这3个因素能够帮助我们更好地理解开花物候格局。     

Increasing temperature decreases the predatory effect of the intertidal shanny Lipophrys pholis on an amphipod prey

Interactions between Lipophrys pholis and its amphipod prey Echinogammarus marinus were used to investigate the effect of changing water temperatures, comparing current and predicted mean summer temperatures. Contrary to expectations, predator attack rates significantly decreased with increasing temperature. Handling times were significantly longer at 19° C than at 17 and 15° C and the maximum feeding estimate was significantly lower at 19° C than at 17° C. Functional‐response type changed from a destabilizing type II to the more stabilizing type III with a temperature increase to 19° C. This suggests that a temperature increase can mediate refuge for prey at low densities. Predatory pressure by teleosts may be dampened by a large increase in temperature (here from 15 to 19° C), but a short‐term and smaller temperature increase (to 17° C) may increase destabilizing resource consumption due to high maximum feeding rates; this has implications for the stability of important intertidal ecosystems during warming events.     

Mechanisms driving plant functional trait variation in a tropical forest

Plant functional trait variation in tropical forests results from taxonomic differences in phylogeny and associated genetic differences, as well as, phenotypic plastic responses to the environment. Accounting for the underlying mechanisms driving plant functional trait variation is important for understanding the potential rate of change of ecosystems since trait acclimation via phenotypic plasticity is very fast compared to shifts in community composition and genetic adaptation. We here applied a statistical technique to decompose the relative roles of phenotypic plasticity, genetic adaptation, and phylogenetic constraints. We examined typically obtained plant functional traits, such as wood density, plant height, specific leaf area, leaf area, leaf thickness, leaf dry mass content, leaf nitrogen content, and leaf phosphorus content. We assumed that genetic differences in plant functional traits between species and genotypes increase with environmental heterogeneity and geographic distance, whereas trait variation due to plastic acclimation to the local environment is independent of spatial distance between sampling sites. Results suggest that most of the observed trait variation could not be explained by the measured environmental variables, thus indicating a limited potential to predict individual plant traits from commonly assessed parameters. However, we found a difference in the response of plant functional traits, such that leaf traits varied in response to canopy‐light regime and nutrient availability, whereas wood traits were related to topoedaphic factors and water availability. Our analysis furthermore revealed differences in the functional response of coexisting neotropical tree species, which suggests that endemic species with conservative ecological strategies might be especially prone to competitive exclusion under projected climate change.     

Late Quaternary climate legacies in contemporary plant functional composition

The functional composition of plant communities is commonly thought to be determined by contemporary climate. However, if rates of climate‐driven immigration and/or exclusion of species are slow, then contemporary functional composition may be explained by paleoclimate as well as by contemporary climate. We tested this idea by coupling contemporary maps of plant functional trait composition across North and South America to paleoclimate means and temporal variation in temperature and precipitation from the Last Interglacial (120 ka) to the present. Paleoclimate predictors strongly improved prediction of contemporary functional composition compared to contemporary climate predictors, with a stronger influence of temperature in North America (especially during periods of ice melting) and of precipitation in South America (across all times). Thus, climate from tens of thousands of years ago influences contemporary functional composition via slow assemblage dynamics.     

Winter severity determines functional trait composition of phytoplankton in seasonally ice‐covered lakes

How climate change will affect the community dynamics and functionality of lake ecosystems during winter is still little understood. This is also true for phytoplankton in seasonally ice‐covered temperate lakes which are particularly vulnerable to the presence or absence of ice. We examined changes in pelagic phytoplankton winter community structure in a north temperate lake (Müggelsee, Germany), covering 18 winters between 1995 and 2013. We tested how phytoplankton taxa composition varied along a winter‐severity gradient and to what extent winter severity shaped the functional trait composition of overwintering phytoplankton communities using multivariate statistical analyses and a functional trait‐based approach. We hypothesized that overwintering phytoplankton communities are dominated by taxa with trait combinations corresponding to the prevailing winter water column conditions, using ice thickness measurements as a winter‐severity indicator. Winter severity had little effect on univariate diversity indicators (taxon richness and evenness), but a strong relationship was found between the phytoplankton community structure and winter severity when taxon trait identity was taken into account. Species responses to winter severity were mediated by the key functional traits: motility, nutritional mode, and the ability to form resting stages. Accordingly, one or the other of two functional groups dominated the phytoplankton biomass during mild winters (i.e., thin or no ice cover; phototrophic taxa) or severe winters (i.e., thick ice cover; exclusively motile taxa). Based on predicted milder winters for temperate regions and a reduction in ice‐cover durations, phytoplankton communities during winter can be expected to comprise taxa that have a relative advantage when the water column is well mixed (i.e., need not be motile) and light is less limiting (i.e., need not be mixotrophic). A potential implication of this result is that winter severity promotes different communities at the vernal equinox, which may have different nutritional quality for the next trophic level and ecosystem‐scale effects.     

不同气候带间成熟林植物叶性状间异速生长关系随功能型的变异

为研究不同生物气候带内植物叶片大小与叶柄干重间的异速生长关系, 探讨不同植物功能型对叶内异速生长关系的效应, 在黑龙江呼中、吉林长白山、北京东灵山、浙江古田山、湖北神农架和四川都江堰6个地区, 选择典型地带性成熟林进行主要木本植物的叶片和叶柄性状的测定与统计分析。结果表明: 不同功能型和气候带植物叶片干重、面积、体积均与叶柄干重之间存在着显著的异速生长关系, 共同斜率分别为0.82、0.70和0.80, 均显著小于1.0。在相同叶柄干重下, 灌木较乔木支持更大的叶片体积, 但它们支持的叶片干重与叶片面积无显著差异; 常绿植物在给定叶柄干重下较落叶植物支持更高的叶片干重与体积, 但其支持的叶片面积小于落叶植物; 除神农架地区外, 在给定叶柄干重下, 亚热带的古田山、都江堰地区的植物较温带地区的植物支持更大的叶片干重、面积与体积, 而亚热带神农架地区的植物叶柄支持的叶片大小(面积、体积、干重)与温带地区相近。结果表明, 叶柄限制了叶片的不断增大(包括面积、体积和干重), 叶片和叶柄之间的异速生长关系受功能型、气候带及生境条件的影响。     

吉林灌木群落物种多样性与气候和局域环境因子的关系

为了研究气候和局域环境因子对物种多样性的相对作用大小,以及验证两种均匀度地理格局的假说在半湿润地区次生灌丛的适用性,对吉林东、南部地区的灌木群落进行了研究。共调查森林破坏后形成的次生灌丛样方45个,结合气候数据和局域环境因子数据,研究了气候、局域环境因子对群落、灌木层、草本层的物种丰富度、均匀度的影响,以及对不同水分生态型(旱生、旱中生、湿中生)灌木影响的差异。结果表明:1)吉林次生灌丛的群落、草本层物种丰富度,以及草本层均匀度,随纬度增加而显著上升。2)对物种多样性和气候、局域环境因子的分析表明,群落、草本层物种数主要受局域环境因子而不是气候的影响;其物种丰富度与纬度的反常关系,是由于灌木层盖度随降水增加而上升,从而导致物种数下降。灌木层物种数与纬度、气候因子的相关性不显著,则是由于不同水分生态型对气候梯度的响应不一致,反映出功能群对多样性格局的影响。3)群落、灌木层均匀度主要受气候因子的影响;而草本层均匀度主要受局域环境因子的影响,降水同样通过对灌木层盖度的影响间接作用于草本均匀度。但群落、灌木和草本层的结果,都支持均匀度随着环境条件改善而增加的假说,而不支持随着生产力增加、竞争加剧,从而导致均匀度下降的假说。结果表明,物种丰富度和均匀度的影响机制存在很大差异,但二者都受到局域环境因子的强烈影响。气候通过局域生物因素(如盖度、生活型)间接作用于多样性格局,是气候对多样性影响的一个重要方面,但尚未得到应有的重视。由于局域生物因素也随气候而变化,仅研究多样性和气候的表面关系,将无法准确预测气候变化对多样性的影响。     

Growing‐season temperature and precipitation are independent drivers of global variation in xylem hydraulic conductivity

Stem xylem‐specific hydraulic conductivity (K_S) represents the potential for plant water transport normalized by xylem cross section, length, and driving force. Variation in K_S has implications for plant transpiration and photosynthesis, growth and survival, and also the geographic distribution of species. Clarifying the global‐scale patterns of K_S and its major drivers is needed to achieve a better understanding of how plants adapt to different environmental conditions, particularly under climate change scenarios. Here, we compiled a xylem hydraulics dataset with 1,186 species‐at‐site combinations (975 woody species representing 146 families, from 199 sites worldwide), and investigated how K_S varied with climatic variables, plant functional types, and biomes. Growing‐season temperature and growing‐season precipitation drove global variation in K_S independently. Both the mean and the variation in K_S were highest in the warm and wet tropical regions, and lower in cold and dry regions, such as tundra and desert biomes. Our results suggest that future warming and redistribution of seasonal precipitation may have a significant impact on species functional diversity, and is likely to be particularly important in regions becoming warmer or drier, such as high latitudes. This highlights an important role for K_S in predicting shifts in community composition in the face of climate change.     

Species traits and climate velocity explain geographic range shifts in an ocean‐warming hotspot

Species' ranges are shifting globally in response to climate warming, with substantial variability among taxa, even within regions. Relationships between range dynamics and intrinsic species traits may be particularly apparent in the ocean, where temperature more directly shapes species' distributions. Here, we test for a role of species traits and climate velocity in driving range extensions in the ocean‐warming hotspot of southeast Australia. Climate velocity explained some variation in range shifts, however, including species traits more than doubled the variation explained. Swimming ability, omnivory and latitudinal range size all had positive relationships with range extension rate, supporting hypotheses that increased dispersal capacity and ecological generalism promote extensions. We find independent support for the hypothesis that species with narrow latitudinal ranges are limited by factors other than climate. Our findings suggest that small‐ranging species are in double jeopardy, with limited ability to escape warming and greater intrinsic vulnerability to stochastic disturbances.     

Changes in leaf nitrogen and phosphorus stoichiometry of woody plants along an altitudinal gradient in Changbai Mountain,China

Aims Leaf is the organ of plant photosynthesis, and it is important to understand the drivers for the variations of leaf nitrogen (N) and phosphorus (P) stoichiometry along geographical and climatic gradients. Here we aimed to explore: 1) the changes in leaf nitrogen (N) and phosphorus (P) stoichiometry of woody plants along an altitudinal gradient in Changbai Mountain, and 2) the relative contribution of climate, plant characteristics, and phylogeny to the changes in leaf N, P concentration and N:P.     

Plant functional groups mediate effects of climate and soil factors on species richness and community biomass in grasslands of Mongolian Plateau

植物功能群在调控气候和土壤因子对蒙古高原草原群落物种丰富度和生物量影响中的作用 植物功能群组成主要受环境因素驱动,同时植物功能群组成也是影响草地生物多样性和生产力的主要因素之一。因此,理解植物功能群在调控环境因素对生态系统功能和生物多样性影响中可能发挥的作用至关重要。通过对蒙古高原草原65个样点的植物生物量和物种丰富度的调查,将157种多年生草本植物分为两种植物功能群(即禾草和杂类草)。通过随机森林模型和普通最小二乘回归,确定与植物功能群物种丰富度和地上生物量显著相关的环境因素(即干燥度、土壤总氮和pH),并利用结构方程模型探讨筛选出的环境因素与群落物种丰富度和生物量间的关系,以及植物功能群在驱动这种关系中发挥的作用。干燥度与禾草、杂类草以及整个群落的地上生物量和物种丰富度均呈显著的单峰关系。所有的物种丰富度和生物量指标均与土壤总氮和pH值显著相关。禾草在维持蒙古高原草原生态系统群落生物量中起着关键作用,并受气候因素的直接影响。而杂类草物种丰富度决定了群落总丰富度,并受到土壤因素直接的调控。因此,群落组成在调控环境因素对群落生物量和植物多样性的影响中起着关键作用。