Accepted ArticleThis article is protected by copyright. All rights reservedThe growth and survival of individual trees determine the physical structure of a forest with important consequences for forest function. However, given the diversity of tree species and forest biomes, quantifying the multitude of demographic strategies within and across forests and the way that they translate into forest structure and function remains a significant challenge. Here, we quantify the demographic rates of 1,961 tree species from temperate and tropical forests and evaluate how demographic diversity (DD) and demographic composition (DC) differ across forests, and how these differences in demography relate to species richness, aboveground biomass, and carbon residence time.We find wide variation in DD and DC across forest plots, patterns that are not explained by species richness or climate variables alone. There is no evidence that DD has an effect on either aboveground biomass or carbon residence time.Rather, the DC of forests, specifically the relative abundance of large statured species, predicted both biomass and carbon residence time. Our results demonstrate the distinct demographic compositions of globally distributed forests, reflecting biogeography, recent history, and current plot conditions. Linking the demographic composition of forests to resilience or vulnerability to climate change, will improve the precision and accuracy of predictions of future forest composition, structure and function.

Questions:Quantifying tree species persistence through recurrent disturbances is of crucial importance for understanding forest dynamics in typhoon-prone regions.We ask the following: (a) What are the major determinants of dominant tree survival in frequently typhoon-disturbed forests? (b) Are survival determinants different between small and large trees?Location: A subtropical old-growth forest located in Fushan, Taiwan (24°45′34″N, 121°33′58″E), with frequent typhoon disturbances.Methods: Data were from three consecutive censuses of a 25-ha permanent forest plot that censused trees ≥1 cm in diameter every five years. The survival of three dominant tree species was modeled using generalized additive model and boosted trees with abiotic and biotic predictors. We evaluated model performance using validation data obtained from the two available census intervals.Results: Model validations showed that multi-stemming and tree size enhanced the survival of large and small trees, respectively. For the most dominant species, multi-stemming had a consistently positive effect on survival irrespective of diameter classes. Abiotic factors and conspecific density had little effect on tree survival. Furthermore, evaluating model performance based on the data used in the model construction (i.e., training data) overestimated the predictive ability of survival models. Conclusions:We showed that the survival determinants for the three most dominant species at Fushan changed from tree size for small trees to multi-stemming for large trees. The results suggest that the dominant species in this frequently typhoon-disturbed forest have the stature and architectural traits to persist, and thereby maintain their dominance and shape the forest physiognomy. Our approach illustrates how datasets from different census periods can be used in model validation to better assess model performance. K E Y W O R D Sdevelopmental change, Fushan Forest Dynamics Plot, life history strategy, mortality, multistemming, sprouting, subtropical forest, survival, tree size, typhoon disturbance 430 |

Lack of tree fecundity data across climatic gradients precludes the analysis of how seed supply contributes to global variation in forest regeneration and biotic interactions responsible for biodiversity. A global synthesis of raw seedproduction data shows a 250‐fold increase in seed abundance from cold‐dry to warm‐wet climates, driven primarily by a 100‐fold increase in seed production for a given tree size. The modest (threefold) increase in forest productivity across the same climate gradient cannot explain the magnitudes of these trends. The increase in seeds per tree can arise from adaptive evolution driven by intense species interactions or from the direct effects of a warm, moist climate on tree fecundity. Either way, the massive differences in seed supply ramify through food webs potentially explaining a disproportionate role for species interactions in the wet tropics.

Accurate estimates of forest biomass stocks and fluxes are needed to quantify global carbon budgets and assess the response of forests to climate change. However, most forest inventories consider tree mortality as the only aboveground biomass (AGB) loss without accounting for losses via damage to living trees: branchfall, trunk breakage,

The latitudinal gradient of declining species richness at higher latitudes is among the most fundamental patterns in ecology. However, whether changes in species composition across space (beta-diversity) contribute to this global gradient of species richness remains debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in high gamma-diversity areas to inflate measures of beta-diversity. We provide here a rigorous test, comparing species-packing and local heterogeneity across a latitudinal gradient in tree species richness in Asia, using beta-diversity metrics that correct the gamma-diversity and sampling bias. Our data include 21 large forest plots across a wide environmental gradient in East Asia. We demonstrate that local beta-diversity increases with topographic heterogeneity, but after accounting for this and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate, contributing to the latitudinal gradient of species richness. This supports the hypothesis of tighter species packing and larger niche space in tropical forests while demonstrating the importance of local processes in controlling beta-diversity.