Through litter decomposition enormous amounts of carbon is emitted to the atmosphere. Numerous large-scale decomposition experiments have been conducted focusing on this fundamental soil process in order to understand the controls on the terrestrial carbon transfer to the atmosphere. However, previous studies were mostly based on site-specific litter and methodologies, adding major uncertainty to syntheses, comparisons and meta-analyses across different experiments and sites. In the TeaComposition initiative, the potential litter decomposition is investigated by using standardized substrates (Rooibos and Green tea) for comparison of litter mass loss at 336 sites (ranging from -9 to +26 °C MAT and from 60 to 3113 mm MAP) across different ecosystems. In this study we tested the effect of climate (temperature and moisture), litter type and land-use on early stage decomposition (3 months) across nine biomes. We show that litter quality was the predominant controlling factor in early stage litter decomposition, which explained about 65% of the variability in litter decomposition at a global scale. The effect of climate, on the other hand, was not litter specific and explained <0.5% of the variation for Green tea and 5% for Rooibos tea, and was of significance only under unfavorable decomposition conditions (i.e. xeric versus mesic environments). When the data were aggregated at the biome scale, climate played a significant role on decomposition of both litter types (explaining 64% of the variation for Green tea and 72% for Rooibos tea). No significant effect of land-use on early stage litter decomposition was noted within the temperate biome. Our results indicate that multiple drivers are affecting early stage litter mass loss with litter quality being dominant. In order to be able to quantify the relative importance of the different drivers over time, long-term studies combined with experimental trials are needed.

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1.One of the major problems in understanding growth trends in long-lived trees is the difficulty of separately quantifying the effects of tree size and age. Careful statistical control of the axiomatic age×size covariation is therefore required to identify long-term trends in tree growth and their drivers, and to predict forests' responses to environmental changes reliably. 2.To address this issue, we present a novel tree growth model: a 'two-dimensional lognormal growth model'. This is an extension of the one-dimensional lognormal growth model, in which tree growth is modelled primarily as a function of size. Our model assesses the trend in tree growth over time by explicitly partitioning the effects of age and size, controlling the covariation. The model is then extended to incorporate the effects of neighbourhood crowding and individual tree variation. 3.To demonstrate our model, we apply it to long-term monitoring data from a mature (104-yearold) plantation of Japanese cedar. Thinning operations of various intensities have been applied to this plantation, and the diameter of each individual tree has been measured repeatedly. 4.We observed a pronounced age-related decline in diameter growth. However, at each age, greater tree size was associated with a higher growth rate. The growth-size curve predicted from the model became flatter with tree age, and the curve's peak shifted rightwards as tree age increased. The model reveals that the sensitivity of a target tree to neighbourhood crowding depends strongly on neighbours' size, and also provides an estimate of among-tree variation in Accepted ArticleThis article is protected by copyright. All rights reserved. growth performance. 5.Although the relationships between growth, size and age in long-lived trees are very complex, our growth model supports the conclusion that it is possible to predict long-term trends in tree growth reliably with respect to both age and size. In addition, the model's flexibility will facilitate more robust testing of species-specific responses to long-term environmental changes.

We investigated the structure and dynamics of the multi-stemmed understory shrub Lindera triloba (Sieb. et Zucc.) Blume over 3 years in an old-growth coniferous forest, and quantitatively evaluated the factors affecting the ramet production, growth, and survival. Most genets sprouted continuously and exhibited multiple-stemmed structures with a few large and many small ramets. The skewed ramet-size distribution within genets resulted from the local crowding of neighboring trees, but not from the number of ramets within genets. This indicated that inter-plant competition is asymmetric (i.e., larger individuals outcompete one-sidedly smaller ones), but intra-plant competition (i.e., competition among ramets within genets) is symmetric (i.e., smaller ones also competitively affect larger ones). The local crowding of neighboring understory trees consistently negatively affected the ramet production, growth, and survival of L. triloba. Intra-genet crowding (i.e., crowding of ramets within genets) also negatively affected the ramet dynamics. On the other hand, the largest-ramet size within genets had positive relationships with the ramet dynamics, indicating that physiological integration within genets plays a role as supporting younger ramets. Based on our results, to fully understand genet persistence strategies in clonal shrub species, it is important to consider the effects of intra-genet crowding and modular integration, as well as plant-to-plant interaction.

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Subdioecy is thought to occupy a transitional position in the gynodioecy-dioecy pathway, explaining one of the evolutionary routes from hermaphroditism to dioecy. Quantifying any female reproductive advantage of females versus hermaphrodites is fundamental to examining the spectrum between subdioecy and dioecy; however, this is challenging, as multiple interacting factors, such as pollen limitation and resource availability, affect plant reproduction. We compared the female reproductive success of females and hermaphrodites via a field experiment in which we hand-pollinated individuals of the subdioecious shrub Eurya japonica of similar size growing under similar light conditions. Effects of pollen limitation and seed quality were also evaluated through comparing the results of hand- and natural-pollination treatments and performing additional laboratory and greenhouse experiments. Overall, females had higher fruit set and produced heavier fruit and more seeds than hermaphrodites, and these results were more pronounced for hand-pollinated than for natural-pollinated plants of both sexes. We also found that seeds naturally produced by females had a higher mean germination rate. These results indicate that females had a pronounced advantage in female reproductive success under conditions of no pollen limitation. The sexual difference in the degree of pollen limitation suggests a pollinator-mediated interaction, whereas the higher female reproductive success of females even under natural conditions implies that E. japonica is a good model species for elucidating the later stages of the gynodioecy-dioecy pathway.

We tested the effect of general flowering (GF), community‐wide masting, and drought stress on current‐year tree diameter growth and aboveground biomass increment (ABI). General flowering but not drought had a marginally significant negative effect on tree growth and ABI at the community level. Analyses of dominant species clarified this pattern.

In L. triloba, physiological integration exists at the whole-plant level, and sprouted ramets are dependent on assimilates translocated from main ramets, but this dependence weakens as sprouted ramets get larger. Female sprouted ramets can grow in a physiologically independent manner from the main ramet earlier than those of males. This study highlights the importance of considering modular structures and physiological integration when evaluating sexual differences in demographic patterns of clonal plants.