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.

No abstract

No abstract

No abstract

Potential species replacement within low-diversity shrub thicket communities was investigated for a Virginia barrier island. Seed bank species composition was quantified in a glasshouse study using soil samples collected beneath closed Myrica cerifera thickets, as well as from thicket gaps. Samples were collected from productive and aging thickets, corresponding to differences in soil age. These data were compared to species presently occurring within the thickets and gaps. Seedbank species composition was not indicative of current community composition for either the intact thickets or the gaps. Seed banks resembled a more pioneer community. Thirteen families, 23 genera, and 25 species were identified from the seed bank beneath the M. cerifera thickets. Four species were woody. The within-gap seed bank included 19 families, 30 genera, and 34 species. Eight species were woody. The current community included 21 families, 33 genera, and 36 species beneath the intact thickets as well as within the thicket gaps. Eighteen species were woody. The species richness of gaps was more than three times that of intact thickets. For low-diversity shrub thickets, gaps enhance species richness.