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Climate data matching the scales at which organisms experience climatic conditions are often missing. Yet, such data on microclimatic conditions are required to better understand climate change impacts on biodiversity and ecosystem functioning. Here we combine a network of microclimate temperature measurements across different habitats and vertical heights with a novel radiative transfer model to map daily temperatures during the vegetation period at 10 meter spatial resolution across Switzerland. Our data reveals strong horizontal and vertical variability in microclimate temperature, particularly for maximum temperatures at 5 cm above the ground and within the topsoil. Compared to macroclimate conditions as measured by weather stations outside forests, diurnal air and topsoil temperature ranges inside forests were reduced by up to 3.0 and 7.8 °C, respectively, while below trees outside forests, e.g. in hedges and below solitary trees, this buffering effect was 1.8 and 7.2 °C. We also found that in open grasslands, maximum temperatures at 5 cm above ground are on average 3.4 °C warmer than that of macroclimate, suggesting that in such habitats heat exposure close to the ground is often underestimated when using macroclimatic data. Spatial interpolation was achieved by using a hybrid approach based on linear mixed effects models with input from detailed radiation estimates that account for topographic and vegetation shading, as well as other predictor variables related to the macroclimate, topography and vegetation height. After accounting for macroclimate effects, microclimate patterns were primarily driven by radiation, with particularly strong effects on maximum temperatures. Results from spatial block cross-validation revealed predictive accuracies as measured by RSME's ranging from 1.18 to 3.43 °C, with minimum temperatures generally being predicted more accurately than maximum temperatures. The microclimate mapping methodology presented here enables a more biologically relevant perspective when analysing climate-species interactions, which is expected to lead to a better understanding of biotic and ecosystem responses to climate and land use change. [ABSTRACT FROM AUTHOR]

Background and aims Climate-change induced warmer spring temperatures advance tree leaf-out and result in earlier shading of the forest floor. Climate change also leads to more frequent droughts. Forest understorey herbs may respond to these environmental changes by varying traits at different hierarchical levels of organization. While trait mean variation at the inter-individual level in response to environmental changes is well-studied, little is known about how variation at the intra-individual level responds. Methods We sampled genets of the forest understorey herb Galium odoratum from 21 populations in three regions in Germany, varying in microclimatic conditions. The genets were transplanted into a common garden, where we applied shading and drought treatments. We measured plant height and leaf length and width, and calculated the coefficient of variation (CV) at different hierarchical levels: intra-population, intra-genet, intra-ramet and intra-shoot. Key results Variance partitioning showed that intra-shoot CV represented most of the total variation, followed by intra-ramet CV. We found significant variation in CV of plant height and leaf width among populations of origin, indicating that CV is at least partly genetically based. The soil temperature at populations' origins correlated negatively with CV in plant height, suggesting adaptation to local conditions. Furthermore, we observed that early shade led to increased intra-ramet CV in leaf length, while drought reduced intra-shoot CV in leaf width. Finally, intra-shoot leaf width mean and CV were independent under control conditions but correlated under drought. Conclusions Our experimental results reveal correlations of intra-individual variation with soil temperature, indicating that intra-individual variation can evolve and may be adaptive. Intra-individual variation responded plastically to drought and shading, suggesting functional changes to improve light capture and reduce evapotranspiration. In conclusion, intra-individual variation makes up the majority of total trait variation in this species and can play a key role in plant adaptation to climatic change. [ABSTRACT FROM AUTHOR]

Forests play a crucial role in fighting climate change by acting as carbon vacuum cleaners, absorbing and storing carbon dioxide (CO2) emissions. Forest edges, which are areas where forests meet grasslands or roads, can store more carbon than the forest interior due to increased sunlight and warmth. Forest edges are becoming more prevalent due to forest fragmentation caused by human activities. Protecting small forest patches and planting new forests, even small ones, is essential in maximizing carbon storage and combating climate change. [Extracted from the article]

Background and Aims Hedgerows have been shown to improve forest connectivity, leading to an increased probability of species tracking the shifting bioclimatic envelopes. However, it is still unknown how species in hedgerows respond to temperature changes, and whether effects differ compared with those in nearby forests. We aimed to elucidate how ongoing changes in the climate system will affect the efficiency of hedgerows in supporting forest plant persistence and migration in agricultural landscapes. Methods Here we report results from the first warming experiment in hedgerows. We combined reciprocal transplantation of plants along an 860-km latitudinal transect with experimental warming to assess the effects of temperature on vegetative growth and reproduction of two common forest herbs (Anemone nemorosa and Geum urbanum) in hedgerows versus forests. Key Results Both species grew taller and produced more biomass in forests than in hedgerows, most likely due to higher competition with ruderals and graminoids in hedgerows. Adult plant performance of both species generally benefitted from experimental warming, despite lower survival of A. nemorosa in heated plots. Transplantation affected the species differently: A. nemorosa plants grew taller, produced more biomass and showed higher survival when transplanted at their home site, indicating local adaptation, while individuals of G. urbanum showed greater height, biomass, reproductive output and survival when transplanted northwards, likely owing to the higher light availability associated with increasing photoperiod during the growing season. Conclusions These findings demonstrate that some forest herbs can show phenotypic plasticity to warming temperatures, potentially increasing their ability to benefit from hedgerows as ecological corridors. Our study thus provides novel insights into the impacts of climate change on understorey plant community dynamics in hedgerows, and how rising temperature can influence the efficiency of these corridors to assist forest species' persistence and colonization within and beyond their current distribution range. [ABSTRACT FROM AUTHOR]

Background and Aims It remains unclear whether invasive species can maintain both high biomass and reproductive output across their invaded range. Along latitudinal gradients, allocation theory predicts that faster flowering onset at high latitudes results in maturation at smaller size and thus reduced reproductive output. For annual invasive plants, more favourable environmental conditions at low latitudes probably result in stronger competition of co-occurring species, potentially driving selection for higher investment in vegetative biomass, while harsher climatic conditions and associated reproductive uncertainty at higher latitudes could reduce selection for vegetative biomass and increased selection for high reproductive investment (stress-gradient hypothesis). Combined, these drivers could result in increased or constant reproductive allocation with increasing latitude. Methods We quantified life-history traits in the invasive annual plant Impatiens glandulifera along a latitudinal gradient in Europe. By growing two successive glasshouse generations, we assessed genetic differentiation in vegetative growth and reproductive output across six populations, and tested whether onset of flowering drives this divergence. Key Results Trait variation was mainly caused by genetic differentiation. As expected, flowering onset was progressively earlier in populations from higher latitudes. Plant height and vegetative biomass also decreased in populations from higher latitudes, as predicted by allocation theory, but their variation was independent of the variation in flowering onset. Reproductive output remained constant across latitudes, resulting in increased reproductive allocation towards higher latitudes, supporting the stress-gradient hypothesis. We also observed trait genetic differentiation among populations that was independent of latitude. Conclusions We show that an annual invasive plant evolved several life-history traits across its invaded range in ~150 years. The evolution of vegetative and reproductive traits seems unconstrained by evolution of flowering onset. This genetic decoupling between vegetative and reproductive traits possibly contributes to the invasion success of this species. [ABSTRACT FROM AUTHOR]

Background and Aims Classic theory on geographical gradients in plant–herbivore interactions assumes that herbivore pressure and plant defences increase towards warmer and more stable climates found at lower latitudes. However, the generality of these expectations has been recently called into question by conflicting empirical evidence. One possible explanation for this ambiguity is that most studies have reported on patterns of either herbivory or plant defences whereas few have measured both, thus preventing a full understanding of the implications of observed patterns for plant–herbivore interactions. In addition, studies have typically not measured climatic factors affecting plant–herbivore interactions, despite their expected influence on plant and herbivore traits. Methods Here we tested for latitudinal variation in insect seed predation and seed traits putatively associated with insect attack across 36 Quercus robur populations distributed along a 20° latitudinal gradient. We then further investigated the associations between climatic factors, seed traits and seed predation to test for climate-based mechanisms of latitudinal variation in seed predation. Key Results We found strong but contrasting latitudinal clines in seed predation and seed traits, whereby seed predation increased whereas seed phenolics and phosphorus decreased towards lower latitudes. We also found a strong direct association between temperature and seed predation, with the latter increasing towards warmer climates. In addition, temperature was negatively associated with seed traits, with populations at warmer sites having lower levels of total phenolics and phosphorus. In turn, these negative associations between temperature and seed traits led to a positive indirect association between temperature and seed predation. Conclusions These results help unravel how plant–herbivore interactions play out along latitudinal gradients and expose the role of climate in driving these outcomes through its dual effects on plant defences and herbivores. Accordingly, this emphasizes the need to account for abiotic variation while testing concurrently for latitudinal variation in plant traits and herbivore pressure. [ABSTRACT FROM AUTHOR]

Bertrand et al. question our interpretation about warming effects on the thermophilization in forest plant communities and propose an alternative way to analyze climatic debt. We show that microclimate warming is a better predictor than macroclimate warming for studying forest plant community responses to warming. Their additional analyses do not affect or change our interpretations and conclusions. [ABSTRACT FROM AUTHOR]

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The colonization rates of understorey plants into forests growing on former agricultural land differ remarkably among species. Different dispersal and recruitment largely account for the contrasting colonization rates, but different effects of the soil legacies of former agricultural land use on plant performance may also play a role. Seven herbaceous forest species were sampled in paired post-agricultural and ancient forest stands to study whether land-use history has an effect on the aboveground nutrient concentrations (N, P and N:P ratios) and biomass of forest herbs and, if so, whether slow and fast colonizing species respond differently. Results showed that P concentrations were significantly affected by former land use with higher concentrations in the post-agricultural stands. N concentrations were unaffected and N:P ratios were significantly higher in the ancient stands. Nutrient concentrations varied considerably among species, but the variation was unrelated to their colonization capacity. Six out of the seven species had higher biomass in the post-agricultural stands relative to the ancient stands, and the degree to which the species increased biomass was positively related to their colonization capacity, i.e., the fast colonizing species showed the strongest increase. Such differential responses to past land use may contribute to the contrasting colonization capacity of forest plants. Land-use history thus affected both the nutrient concentrations and biomass of forest herbs, and only the biomass response was related to colonization capacity. [ABSTRACT FROM AUTHOR]