Wood decomposition and decomposer interactions

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Feldhaar & ThornWood decomposition and decomposer interactions (SP1)Wider research context: Higher tree diversity may be beneficial to saproxylic insects by enhancing the diversity of dead wood and forest heterogeneity. By providing food and nesting space for species foraging in leaf-litter or soil, dead wood is an important link between the above- and below-ground food web.Hypotheses: Here, we propose to study saproxylic insect communities along a tree diversity gradient in the BEF-China experiment. Our main hypotheses are: (1) Tree diversity is positively correlated to the amount and diversity of dead wood, which (2) leads to an increase in (functional trait) diversity of saproxylic insect communities. (3) Higher functional trait diversity of saproxylic insect communities with increasing tree diversity has a positive effect on wood decomposition. (4) Decomposition of suspended dead wood is slower than on the ground due to differences in microclimate and vertical stratification of insect communities.Methods: We will characterize the amount and diversity of naturally occurring dead wood in all core plots to assess resource quality and availability for saproxylic insects (WP1). We will characterize the functional and taxonomic diversity of saproxylic insect communities from dead wood in all core plots. For ants and termites, we will assess species pools from leaf litter and pitfall traps (with SP3 and SP6) since the presence of predatory ants within plots may prevent other insects from colonising dead wood (WP2). In the VIP plots we will expose dead wood from four different tree species and either allow insect colonization or exclude insects. We will characterize saproxylic insect communities in relation to wood traits and will measure wood mass loss (WP3). Moreover, we will compare wood decomposition and colonization by saproxylic insects of suspended dead wood with pieces exposed on the ground, again with and without insect exclusion (WP4).Innovation: We will extend previous work by including tree diversity as a driver of saproxylic insect communities and the entailing decomposition process. We will disentangle the direct effects of tree diversity on decomposer communities from indirect effects mediated through environmental changes affecting the local species pool, thereby altering community assembly processes in dead wood or interactions between decomposers and organisms of other trophic levels.Primary researchers involved: This project will be conducted by Heike Feldhaar (PI, Uni Bayreuth) and Simon Thorn (Co-PI, Uni Würzburg), in collaboration with our Chinese partner Arong Luo (Chinese Academy of Sciences).