Consequences of the reduction of plant diversity for litter decomposition: effects through litter quality and microenvironment

Abstract

Consequences of the reduction of plant diversity for litter decomposition: effects through litter quality and microenvironment. -Oikos 90: 357 -371.Decomposition of plant litter is a key process for the flow of energy and nutrients in ecosystems that may be sensitive to the loss of biodiversity. Two hypothetical mechanisms by which changes in plant diversity could affect litter decomposition are (1) through changes in litter species composition, and (2) by altering the decomposition microenvironment. We tested these ideas in relation to the short-term decomposition of herbaceous plant litter in experimental plant assemblages that differed in the numbers and types of plant species and functional groups that they contained to simulate loss of plant diversity. We used different litterbag experiments to separate the two potential pathways through which diversity could have an effect on decomposition. Our two litterbag trials showed that altering plant diversity affected litter breakdown differently through changes in decomposition microenvironment than through changes in litter composition. In the decomposition microenvironment experiment there was a significant but weak decline in decomposition rate in relation to decreasing plant diversity but no significant effect of plant composition. The litter composition experiment showed no effect of richness but significant effects of composition, including large differences between plant species and functional groups in litter chemistry and decomposition rate. However, for a nested subset of our litter mixtures decomposition was not accurately predicted from single-species bags; there were positive, non-additive effects of litter mixing which enhanced decomposition. We critically assess the strengths and limitations of our short-term litterbag trials in predicting the longer-term effects of changes in plant diversity on litter decomposition rates. MethodsThe litterbag trials were conducted as part of the BIODEPTH project (BIODiversity and Ecosystem Processes in Terrestrial Herbaceous systems: experimental manipulations of plant communities): a co-ordinated network of eight European fieldsites where the responses of a suite of ecosystem processes are monitored in relation to the direct manipulation of plant diversity

Biodiversity and decomposition in experimental grassland ecosystems

“…Species differ in aboveground litter quality, but the pattern of soil mineral nitrate availability along the species richness gradient is only weakly reflected in the aboveground litter quality gradient. Thus, higher species richness results in an averaging of the species differences in aboveground litter quality without significant interactions along a species richness gradient, as reported by Wardle et al (1997) and Hector et al (2000). This supports the hypothesis that litter production increases with higher plant species richness because of increased productivity.…”

“…However, litter decomposition studies have not shown consistent effects of plant species diversity on decomposition rates (Blair et al 1990;Elliott et al 1993;Fyles and Fyles 1993;Hart et al 1993;Klemmedson 1991;Knops et al 1996;Kochy and Wilson 1997;Taylor et al 1989;Williams and Alexander 1991). Four recent studies have specifically examined the effect of litter diversity on decomposition (Bardgett and Shine 1999;Finzi and Canham 1998;Hector et al 2000;Wardle et al 1997). Finzi and Canham (1998) and Hector et al (2000) found significant, but non-additive effects and Wardle et al (1997) found that biodiversity itself was not a significant determinant of decomposition rate.…”

“…Four recent studies have specifically examined the effect of litter diversity on decomposition (Bardgett and Shine 1999;Finzi and Canham 1998;Hector et al 2000;Wardle et al 1997). Finzi and Canham (1998) and Hector et al (2000) found significant, but non-additive effects and Wardle et al (1997) found that biodiversity itself was not a significant determinant of decomposition rate. In contrast, Bardgett and Shine (1999) studied six herbaceous species and found that increased litter diversity corresponded to increased litter decomposition and increased efficiency of soil biological processes.…”

Drivers of nitrogen leaching from organic layers in Central European beech forests

“…3b), short-term laboratory studies indicated a positive e ect of earthworms on nitri cation in soils containing beech litter (Scheu 1997). While the e ect diminished in mixed litter treatments (beech, nettle) because of N transfer among litter species, other studies reported increased mineralization and leaching due to mixing of soil organic matter and mineral soil (Hector et al 2000;Xiong et al 2014). …”

Influence of fire history and soil properties on plant species richness and functional diversity in a neotropical savanna

“…Measures of community functioning (e.g., productivity and nutrient cycling) have typically been found to be more consistently associated with functional diversity than with species richness Influence of fire history and soil properties on plant species richness and functional diversity in a neotropical savanna Hector et al 2000). There is growing evidence that functional diversity strongly determines ecosystem-level processes, such as resource acquisition, nutrient cycling, and productivity (e.g., Hooper & Vitousek 1997;Díaz & Cabido 2001;Hooper et al 2005).…”