Early stage litter decomposition across biomes

Abstract

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.

Response of Organic Matter Decomposition to No-Tillage Adoption Evaluated by the Tea Bag Technique

“…The effect of OM quality is known to be one of the key drivers of litter decomposition [26]. As expected, we found that high quality OM (green tea) was significantly (paired t-test, p < 0.001, n = 13) more decomposed than low quality OM (rooibos tea; Figure 2), confirming the direct influence of OM quality on mass loss rates [18,27]. Average decomposed mass of green tea (high quality organic matter (OM)) and rooibos tea (low quality OM).…”

“…The chronosequence approach used in the present study allowed us to isolate time from the other factors controlling this process, namely climatic conditions and soil properties [18]. Our study indicates that converting CT to NT might favor the decomposition of both low and high quality OM during the transition period.…”

“…Our study indicates that converting CT to NT might favor the decomposition of both low and high quality OM during the transition period. It must be noted that, even though the 30-day period of this experiment provides insight into the early stage of organic matter decomposition, long term decomposition involves other litter components [18], thus our results should not be extrapolated over the long run. Moreover, although our findings are in line with the accumulating evidence supporting the idea that microbial activity is higher in NT soil relative to CT soil, this work was a one-time area-specific study.…”

“…Commercially available tea bags are used as litterbags and the approach has the benefits of being a cost-effective and well-standardized method that can be used all over the world. By gathering data from 336 sites across different ecosystems, Djukic et al [18] have evidenced that this technique might be successfully used to identify the drivers of early stage litter decomposition at both global and biome scales. Tóth et al [19] have also shown that this approach might be used as an ecological indicator to assess impacts of agri-environmental schemes on soil functioning.…”

“…For this purpose, we investigated tea decomposition in soils along a chronosequence of 13 plots of different years under NT in northern France. This approach allowed us to isolate the effect of the time factor from other factors controlling OM decomposition, namely climatic conditions and soil properties [18].…”