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1. Woody species' requirements and environmental sensitivity change from seedlings to adults, a process referred to as ontogenetic shift. Such shifts can be increased by climate change. To assess the changes in the difference of temperature experienced by seedlings and adults in the context of climate change, it is essential to have reliable climatic data over long periods that capture the thermal conditions experienced by the individuals throughout their life cycle. 2. Here we used a unique cross-European database of 2,195 pairs of resurveyed forest plots with a mean intercensus time interval of 37 years. We inferred macroclimatic temperature (free-air conditions above tree canopies--representative of the conditions experienced by adult trees) and microclimatic temperature (representative of the juvenile stage at the forest floor, inferred from the relationship between canopy cover, distance to the coast and below-canopy temperature) at both surveys. We then address the long-term, large-scale and multitaxa dynamics of the difference between the temperatures experienced by adults and juveniles of 25 temperate tree species. 3. We found significant, but species-specific, variations in the perceived temperature (calculated from presence/absence data) between life stages during both surveys. Additionally, the difference of the temperature experienced by the adult versus juveniles significantly increased between surveys for 8 of 25 species. We found evidence of a relationship between the difference of temperature experienced by juveniles and adults over time and one key functional trait (i.e. leaf area). Together, these results suggest that the temperatures experienced by adults versus juveniles became more decoupled over time for a subset of species, probably due to the combination of climate change and a recorded increase of canopy cover between the surveys resulting in higher rates of macroclimate than microclimate warming. 4. Synthesis. We document warming and canopy-cover induced changes in the difference of the temperature experienced by juveniles and adults. These findings have implications for forest management adaptation to climate change such as the promotion of tree regeneration by creating suitable species-specific microclimatic conditions. Such adaptive management will help to mitigate the macroclimate change in the understorey layer. [ABSTRACT FROM AUTHOR]

Forest vegetation and soils have been suggested as potentially important sinks for carbon (C) with appropriate management and thus are implicated as effective tools in stabilizing climate even with increasing anthropogenic release of CO2. Drought, however, which is often predicted to increase in models of future climate change, may limit net primary productio ( NPP) of dry forest types, with unknown effects on soil C storage. We studied C dynamics of a deciduous temperate forest of Hungary that has been subject to significant decreases in precipitation and increases in temperature in recent decades. We resampled plots that were established in 1972 and repeated the full C inventory by analyzing more than 4 decades of data on the number of living trees, biomass of trees and shrubs, and soil C content. Our analyses show that the decline in number and biomass of oaks started around the end of the 1970s with a 71% reduction in the number of sessile oak stems by 2014. Projected growth in this forest, based on the yield table's data for Hungary, was 4.6 kg C/m2. Although new species emerged, this new growth and small increases in oak biomass resulted in only 1.9 kg C/m2 increase over 41 years. The death of oaks increased inputs of coarse woody debris to the surface of the soil, much of which is still identifiable, and caused an increase of 15.5%, or 2.6 kg C/m2, in the top 1 m of soil. Stability of this fresh organic matter input to surface soil is unknown, but is likely to be low based on the results of a colocated woody litter decomposition study. The effects of a warmer and drier climate on the C balance of forests in this region will be felt for decades to come as woody litter inputs decay, and forest growth remains impeded. [ABSTRACT FROM AUTHOR]