Understanding how plants are constructed—i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals—is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among species adapted to different environments. While a variety of models dealing with biomass allocation exist, we lack a synthetic understanding of the underlying processes. This is partly due to the lack of suitable data sets for validating and parameterizing models. To that end, we present the Biomass And Allometry Database (BAAD) for woody plants. The BAAD contains 259 634 measurements collected in 176 different studies, from 21 084 individuals across 678 species. Most of these data come from existing publications. However, raw data were rarely made public at the time of publication. Thus, the BAAD contains data from different studies, transformed into standard units and variable names. The transformations were achieved using a common workflow for all raw data files. Other features that distinguish the BAAD are: (i) measurements were for individual plants rather than stand averages; (ii) individuals spanning a range of sizes were measured; (iii) plants from 0.01–100 m in height were included; and (iv) biomass was estimated directly, i.e., not indirectly via allometric equations (except in very large trees where biomass was estimated from detailed sub‐sampling). We included both wild and artificially grown plants. The data set contains the following size metrics: total leaf area; area of stem cross‐section including sapwood, heartwood, and bark; height of plant and crown base, crown area, and surface area; and the dry mass of leaf, stem, branches, sapwood, heartwood, bark, coarse roots, and fine root tissues. We also report other properties of individuals (age, leaf size, leaf mass per area, wood density, nitrogen content of leaves and wood), as well as information about the growing environment (location, light, experimental treatment, vegetation type) where available. It is our hope that making these data available will improve our ability to understand plant growth, ecosystem dynamics, and carbon cycling in the world's vegetation.

Accurate estimation of tree and forest biomass is key to evaluating forest ecosystem functions and the global carbon cycle. Allometric equations that estimate tree biomass from a set of predictors, such as stem diameter and tree height, are commonly used. Most allometric equations are site specific, usually developed from a small number of trees harvested in a small area, and are either species specific or ignore interspecific differences in allometry. Due to lack of site‐specific allometries, local equations are often applied to sites for which they were not originally developed (foreign sites), sometimes leading to large errors in biomass estimates. In this study, we developed generic allometric equations for aboveground biomass and component (stem, branch, leaf, and root) biomass using large, compiled data sets of 1203 harvested trees belonging to 102 species (60 deciduous angiosperm, 32 evergreen angiosperm, and 10 evergreen gymnosperm species) from 70 boreal, temperate, and subtropical natural forests in Japan. The best generic equations provided better biomass estimates than did local equations that were applied to foreign sites. The best generic equations included explanatory variables that represent interspecific differences in allometry in addition to stem diameter, reducing error by 4–12% compared to the generic equations that did not include the interspecific difference. Different explanatory variables were selected for different components. For aboveground and stem biomass, the best generic equations had species‐specific wood specific gravity as an explanatory variable. For branch, leaf, and root biomass, the best equations had functional types (deciduous angiosperm, evergreen angiosperm, and evergreen gymnosperm) instead of functional traits (wood specific gravity or leaf mass per area), suggesting importance of other traits in addition to these traits, such as canopy and root architecture. Inclusion of tree height in addition to stem diameter improved the performance of the generic equation only for stem biomass and had no apparent effect on aboveground, branch, leaf, and root biomass at the site level. The development of a generic allometric equation taking account of interspecific differences is an effective approach for accurately estimating aboveground and component biomass in boreal, temperate, and subtropical natural forests.

An analysis is presented of three possible pathways of reproductive allocation, namely, allocation of resources to reproductive organs from reproductive shoots, from non‐reproductive shoots and from the main trunk. These pathways were examined by comparing the amount of storage starch in reproductive shoots, non‐reproductive shoots and the main trunk in Styrax obassia, a typical masting tree species, during a year of little flowering (1999) and in a mass‐flowering year (2000). In addition, we measured rates of light‐saturated photosynthesis in leaves of reproductive and non‐reproductive shoots to examine the contribution of photosynthetic production to reproductive costs. In both the main trunk and non‐reproductive shoots the pattern of seasonal variation in the amount of starch did not differ between 1999 and 2000. However, in the mass‐flowering year, the amount of starch in the reproductive shoots was less than that in non‐reproductive shoots during the growing season. Thus, reproductive shoots bore most of the cost of reproduction, although non‐reproductive shoots and the main trunk also bore some of the cost. Mass‐based rates of light‐saturated photosynthesis of the leaves of reproductive shoots were significantly higher than those of non‐reproductive shoots during both the flowering and the fruiting period. However, leaves of reproductive shoots had a significantly smaller area, a lower mass per area, and lower concentrations of nitrogen than leaves of non‐reproductive shoots, although the number of leaves did not differ between the two types of shoots. Therefore, the amount of photosynthate per shoot was significantly lower in reproductive shoots than in non‐reproductive shoots. These results suggest that the cost of reproduction depends predominantly on storage starch in reproductive shoots, although it is still unclear how much photosynthate is allocated to reproductive organs from non‐reproductive shoots.