Complementaridade de atributos reduz a decomposição de folhas em assembleias experimentais
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Data
2018-03-06
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Universidade Federal de Goiás
Resumo
Theoretical and empirical evidence suggest that the mass ratio and the niche complementarity hypothesis are able to explain how species trait composition drives decomposition, an ecosystem process related with nutrient cycling and carbon sequestration. These two hypotheses are respectively related with the mean trait values of individuals present in a given community and its variance. Thus, it is impossible to test them adequately without experiments planned to approach these two aspects simultaneously. Although leaf functional traits influence decomposition process, an experimental design made to disentangle the unique, combined and strength of effects of the mechanisms proposed by MRH and NCH on decomposition should use leaf functional traits as predictors, but this has not yet been done. Here, we used two leaf nutritional traits (leaf nitrogen and magnesium-calcium content) and one structural trait (specific leaf area; SLA) from 20 species of seasonal dry forest to simulate leaf mixtures with different mean trait values (calculated as community-weighted mean; CWM) and variation of trait values (functional diversity; FD). For each trait, 40 leaf mixtures with different quasi-orthogonal combinations of CWM and FD were selected and left in the field to decompose for six months. We found that MRH mechanisms exert predominant role on decomposition where low and high CWM values were related with high biomass loss. Then, this add more evidence to support that the mean trait values of leaf mixtures are the main drivers of biomass loss. Contrary to previously evidences, trait complementarity does not increase efficiency and instead, an increasing in niche complementarity (high FD values) was followed by a decreasing in biomass loss efficiency. So, this question the importance of mechanism behind NCH on leaf decomposition. Additionally, we found that whereas nutritional traits were able to predict leaf decomposition, structural traits were not, in opposite to what is reported in the literature. Our results highlight that the mean resources quality of the leaf mixtures is the main driver of biomass loss and trait complementarity does not increase efficiency of biomass loss. Due to this, we proposed that in future studies mean resources quality of the leaf mixtures will be use as parameter to test and predict the possible impacts of human-induced changes on nutrient cycling and carbon sequestration.
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Atributos funcionais foliares , Diversidade funcional , Funcionamento de comunidades , Efeitos da biodiversidade em processos ecossistêmicos , Ciclagem de nutrientes , Biodiversity effects on ecosystem processes , Community functioning , Functional diversity , Leaf functional traits , Nutrient cycling
Citação
PLAZAS-JIMÉNEZ, D. Complementaridade de atributos reduz a decomposição de folhas em assembleias experimentais. 2018. 50 f. Dissertação (Mestrado em Ecologia e Evolução) - Universidade Federal de Goiás, Goiânia, 2018.