New insights into global decomposition: Analysis from the global wood blocks project

Globally, woody tissue decomposition is a key driver of the carbon flux between the biosphere and atmosphere. Woody species represent ~50% of extant plant diversity and ~4/5 of plant biomass on land, amounting to 457 Gt of carbon. Biotic agents (microbes and invertebrates) are key players in the decomposition of plant woody tissue. Which and how fast these different biotic agents do their job has different consequences on the breakdown of wood and is shaped by abiotic factors, the chemical and morphological traits of the wood, and biogeographical constraints. The interaction among these factors is poorly understood within and across ecosystems worldwide and are not modelled explicitly, decreasing the realism and accuracy of DGVM/biogeochemical models.

Initial analyses of one-year mass-loss data across 115 Global Wood Blocks transects (n = 6900) suggests the response of decomposition to insects increases with temperature and precipitation, and is quite variable, particularly at high temperatures. Second, biological drivers explain more variation in decomposition than environmental heterogeneity due to site to site variation. These findings are an important departure from current biogeophysical models that only assume physical fragmentation of the wood. Building on our initial results, and with the addition of two more years of mass-loss, microbial community composition, and initial and harvested samples chemical data, we will focus on the following themes:

• relative roles of biotic decay agents (both invertebrates and microbes) in decomposing wood within and across ecosystems
• effects of natural environmental gradients (including climate, fertility, elevation and anthropogenic modifications therein) and biogeographic patterns on wood decomposition
• effects of initial wood chemistry and changes in chemistry among sites and treatment through time
• patterns in microbial community composition through space and time and their impact on wood decomposition

Organising committee: 

• Habacuc Flores-Moreno (George Washington University, USA)
• Amy Zanne (George Washington University, USA)
• Jeff Powell (University of Western Sydney, Australia)
• Amy Austin (University of Buenos Aires, Argentina)