Browsing by Author "Jewell, Mark Davidson"
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Item Partitioning the effect of composition and diversity of tree communities on leaf litter decomposition and soil respiration(Wiley, 2016) Jewell, Mark Davidson; Shipley, Bill; Low-Décarie, Etienne; Tobner, Cornelia M; Paquette, Alain; Messier, Christian; Reich, Peter BThe decomposition of plant material is an important ecosystem process influencing both carbon cycling and soil nutrient availability. Quantifying how plant diversity affects decomposition is thus crucial for predicting the effect of the global decline in plant diversity on ecosystem functioning. Plant diversity could affect the decomposition process both directly through the diversity of the litter, and/or indirectly through the diversity of the host plant community and its affect on the decomposition environment. Using a biodiversity experiment with trees in which both functional and taxonomic diversity were explicitly manipulated independently, we tested the effects of the functional diversity and identity of the living trees separately and in combination with the functional diversity and identity of the decomposing litter on rates of litter decomposition and soil respiration. Plant traits, predominantly leaf chemical and physical traits, were correlated with both litter decomposition and soil respiration rates. Surface litter decomposition, quantified by mass loss in litterbags, was best explained by abundance-weighted mean trait values of tree species from which the litter was assembled (functional identity). In contrast, soil respiration, which includes decomposition of dissolved organic carbon and root respiration, was best explained by the variance in trait values of the host trees (functional diversity). This research provides insight into the effect of loss of tree diversity in forests on soil processes. Such understanding is essential to predicting changes in the global carbon budget brought on by biodiversity loss.Item A traits-based test of the home-field advantage in mixed-species tree litter decomposition(Oxford University Press, 2015) Jewell, Mark Davidson; Shipley, Bill; Paquette, Alain; Messier, Christian; Reich, Peter BBackground and Aims Litter often decomposes faster in its environment of origin (at ‘home’) than in a foreign environment (‘away’), which has become known as the home-field advantage (HFA). However, many studies have highlighted the conditional nature of the HFA, suggesting that current understanding of this phenomenon is not yet sufficient to generalize across systems. Methods The HFA hypothesis was tested for mono-specific and mixed-species litter using a tree-based experiment that manipulated the functional identity and diversity of the host tree community. Litter types of varying quality were transplanted between several host tree communities and decomposition rates were measured using litterbags. Since the decomposer community should respond to traits of the litter input and not their taxonomic identity, a traits-based index of litter–tree similarity was developed. Key Results Mono-specific litter exhibited HFA, but when the same litter was decomposed in mixture, this trend was not observed. Mixed-species litter decomposed on average no faster or slower than monoculture litter and exhibited both positive and negative species interactions. These non-additive interactions of decomposition rates in mixture were influenced by the degree of similarity between litter and tree traits. Both synergistic and antagonistic interactions decreased in magnitude with increasing litter–tree similarity such that mixture rates were predictable from monocultures. Conclusions The HFA occurred more strongly for mono-specific litter than for the litter types mixed together because interactions between species may have masked this effect. However, when expressed as a function of trait similarity between litters and tree communities, the HFA was not detected.