• Energy Research

Abstract Whereas temporal variability of plant phenology in response to climate change has already been well studied, the spatial variability of phenology is not well understood. Given that phenological shifts may affect the magnitude of biotic interactions, there is a need to investigate how the variability in environmental factors relates to the spatial variability in herbaceous species’ phenology by at the same time considering their functional traits to predict their general and species-specific responses to future climate change. In this project, we analysed phenology records of 148 herbaceous species, which were observed for a single year by the PhenObs network in 15 botanical gardens. For each species, we characterised the spatial variability in six different phenological stages across gardens. We used boosted regression trees to link these variabilities in phenology to the variability in environmental parameters (temperature, latitude, and local habitat conditions) as well as species traits (seed mass, vegetative height, specific leaf area, and temporal niche) hypothesised to be related to phenology variability. We found that spatial variability in the phenology of herbaceous species was mainly driven by the variability in temperature but also photoperiod was an important driving factor for some phenological stages. In addition, we found that early-flowering and less competitive species indicated by small specific leaf area and vegetative height were more variable in their phenology. Our findings contribute to the field of phenology by showing that besides temperature, photoperiod and functional traits are important to be included when spatial variability of herbaceous species is investigated.

Forest dynamics and demography Tropical forest succession has been viewed mostly by considering trees in categories of early-, mid-, and late-successional species, corresponding to a fast–slow continuum of life history strategies. Rüger et al. now show that the fast–slow continuum does not capture the demographic strategy of the long-lived pioneer species, an important component of many tropical forests (see the Perspective by Bugmann). They developed a forest model that allows for objective predictions of tropical forest dynamics and validated the model's predictions against independent data. These findings should advance our understanding of tropical forest dynamics and facilitate sustainable tropical forest management. Science , this issue p. 165 ; see also p. 128

Data on plant communities (biomass and relative cover of all target species), plant traits (41 different traits, measured on 59 species), and 42 ecosystem properties/functions, measured between 2003 and 2012 in the Jena Main Biodiversity experiment. In floodplain grasslands of the Saale river, near Jena (Germany) 78 20x20 m grassland plots were set up, in which combinations of 1, 2, 4, 8 or 16 species were sown, from a species pool of 60. Thereby, the aim was to create a gradient in plant species richness and functional composition. In each year from 2003-2012, relative cover (in %) of each target species was estimated within 3x3 m subplots. In addition, plant biomass was measured in both spring and summer.In addition, we compiled trait data for 59 of the 60 sown species, based on a combination of existing literature, pot experiments and measurements in the Jena Main Biodiversity experiment monoculture (1-species) plots. Data on 41 traits was collected. Finally, we measured in 41 different ecosystem functions in the Jena Main Biodiversity experiment. Each ecosystem function was measured in at least 3 different years between 2003 and 2012.The "R2.model.random.text[x]" (where x is a number from 1 to 40) are secondary data files, and the outcome of statistical models. In these, 100 times a random subset of 1 to 40 (out of the 41) plant traits were analysed as predictors of the 42 ecosystem functions, in order to assess how the proportion of variance in ecosystem functioning explained by traits (R2 values) depends on the number of traits analysed.

AbstractClimate extremes are on the rise. Impacts of extreme climate and weather events on ecosystem services and ultimately human well‐being can be partially attenuated by the organismic, structural, and functional diversity of the affected land surface. However, the ongoing transformation of terrestrial ecosystems through intensified exploitation and management may put this buffering capacity at risk. Here, we summarize the evidence that reductions in biodiversity can destabilize the functioning of ecosystems facing climate extremes. We then explore if impaired ecosystem functioning could, in turn, exacerbate climate extremes. We argue that only a comprehensive approach, incorporating both ecological and hydrometeorological perspectives, enables us to understand and predict the entire feedback system between altered biodiversity and climate extremes. This ambition, however, requires a reformulation of current research priorities to emphasize the bidirectional effects that link ecology and atmospheric processes.

Summary Phenology has emerged as key indicator of the biological impacts of climate change, yet the role of functional traits constraining variation in herbaceous species’ phenology has received little attention. Botanical gardens are ideal places in which to investigate large numbers of species growing under common climate conditions. We ask whether interspecific variation in plant phenology is influenced by differences in functional traits. We recorded onset, end, duration and intensity of initial growth, leafing out, leaf senescence, flowering and fruiting for 212 species across five botanical gardens in Germany. We measured functional traits, including plant height, absolute and specific leaf area, leaf dry matter content, leaf carbon and nitrogen content and seed mass and accounted for species’ relatedness. Closely related species showed greater similarities in timing of phenological events than expected by chance, but species' traits had a high degree of explanatory power, pointing to paramount importance of species’ life‐history strategies. Taller plants showed later timing of initial growth, and flowered, fruited and underwent leaf senescence later. Large‐leaved species had shorter flowering and fruiting durations. Taller, large‐leaved species differ in their phenology and are more competitive than smaller, small‐leaved species. We assume climate warming will change plant communities’ competitive hierarchies with consequences for biodiversity.

AbstractFundamental axes of variation in plant traits result from trade-offs between costs and benefits of resource-use strategies at the leaf scale. However, it is unclear whether similar trade-offs propagate to the ecosystem level. Here, we test whether trait correlation patterns predicted by three well-known leaf- and plant-level coordination theories – the leaf economics spectrum, the global spectrum of plant form and function, and the least-cost hypothesis – are also observed between community mean traits and ecosystem processes. We combined ecosystem functional properties from FLUXNET sites, vegetation properties, and community mean plant traits into three corresponding principal component analyses. We find that the leaf economics spectrum (90 sites), the global spectrum of plant form and function (89 sites), and the least-cost hypothesis (82 sites) all propagate at the ecosystem level. However, we also find evidence of additional scale-emergent properties. Evaluating the coordination of ecosystem functional properties may aid the development of more realistic global dynamic vegetation models with critical empirical data, reducing the uncertainty of climate change projections.