The origin of litter chemical complexity during decomposition

Abstract

The chemical complexity of decomposing plant litter is a central feature shaping the terrestrial carbon (C) cycle, but explanations of the origin of this complexity remain contentious. Here, we ask: How does litter chemistry change during decomposition, and what roles do decomposers play in these changes? During a long-term (730 days) litter decomposition experiment, we tracked concurrent changes in decomposer community structure and function and litter chemistry using high-resolution molecular techniques. Contrary to the current paradigm, we found that the chemistry of different litter types diverged, rather than converged, during decomposition due to the activities of decomposers. Furthermore, the same litter type exposed to different decomposer communities exhibited striking differences in chemistry, even after > 90% mass loss. Our results show that during decomposition, decomposer community characteristics regulate changes in litter chemistry, which could influence the functionality of litter-derived soil organic matter (SOM) and the turnover and stabilisation of soil C.

Responses of peat carbon at different depths to simulated warming and oxidizing

“…Just like soil characters that are determined by vegetation and vary markedly with climate (Chu et al, 2010;Zak and Kling, 2006), peat as the remains of vegetation may also differ among the whole depth profile as a result of climate change during peat development (Moore and Dalva, 1997) and cryoturbation (O'Donnell et al, 2012;Rinkes et al, 2013;Treat et al, 2014;Wickings et al, 2012). Under a warm and humid climate, peat mainly derives from Cyperaceae and Equisetaceae; under a cool and dry climate, however, it mainly consists of Picea remains (Guo et al, 2013).…”

Impact of fine litter chemistry on lignocellulolytic enzyme efficiency during decomposition of maize leaf and root in soil

“…To our knowledge, this study is the first to assess enzyme efficiency, i.e., the amount of enzyme activity required to decompose the litter, in experiments performed under such tightly controlled conditions. Indeed Sinsabaugh et al (2002) and recently Wickings et al (2012) determined enzyme efficiency in decomposing litter bags under field conditions and noted the importance of other environmental variables, such as climate and soil type, on their results.…”

“…However, most of these studies are based on relationships established between litter mass loss and measured enzyme activities and do not take into account the changes in specific substrates catalyzed by the enzyme of interest nor the complexity of cell walls that hinders substrate degradation (Himmel 2007). In addition most studies addressing the drivers of changes in litter chemistry during decomposition and relationships with enzyme efficiency were performed in situ using litterbags and acknowledge that factors such as soil type, climate or N availability might interfere (Sinsabaugh et al 2002;Wickings et al 2012). An important challenge for understanding and modeling litter decomposition is thus to link enzyme production, activity and turnover to litter quality evolution (Schimel and Weintraub 2003;Allison 2005;Moorhead et al 2012).…”

Long term effects of reduced fertilizer rates on millet yields and soil properties in the West-African Sahel

“…2). There may be no difference in phenols, which are recalcitrant plant derived compounds found in lignin (Grandy and Neff 2008;Wickings et al 2012), due to a combination of factors. First, there is a strong similarity of plant biomass in all cases (millet), which may lead to the same abundance of phenols regardless of treatment.…”

“…Spectroscopic techniques that can directly measure the different chemical forms of organic C and N in soils provide novel information on how nutrients and organic matter (OM) are cycling under different management practices. The forms of C and N that are in soil organic matter (SOM) reflect different points in the decomposition sequence from fresh plant material to decomposed and stabilized materials (Wickings et al 2012). The newly developed soil continuum model (Lehmann and Kleber 2015) considers soil organic matter as having chemical structure and turnover times that are dictated by aggregation with soil, sorption on mineral surfaces, and biological transformations into biopolymers of varying size.…”