Journal Article

Biomass is the main driver of changes in ecosystem process rates during tropical forest succession

Martínez-Ramos, Miguel, Bongers, Frans, Poorter, Lourens, Lohbeck, Madelon

2015

Overview

Over half of the world's forests are disturbed, and the rate at which ecosystem processes recover after disturbance is important for the services these forests can provide. We analyze the drivers' underlying changes in rates of key ecosystem processes (biomass productivity, litter productivity, actual litter decomposition, and potential litter decomposition) during secondary succession after shifting cultivation in wet tropical forest of Mexico. We test the importance of three alternative drivers of ecosystem processes: vegetation biomass (vegetation quantity hypothesis), community-weighted trait mean (mass ratio hypothesis), and functional diversity (niche complementarity hypothesis) using structural equation modeling. This allows us to infer the relative importance of different mechanisms underlying ecosystem process recovery. Ecosystem process rates changed during succession, and the strongest driver was aboveground biomass for each of the processes. Productivity of aboveground stem biomass and leaf litter as well as actual litter decomposition increased with initial standing vegetation biomass, whereas potential litter decomposition decreased with standing biomass. Additionally, biomass productivity was positively affected by community-weighted mean of specific leaf area, and potential decomposition was positively affected by functional divergence, and negatively by community-weighted mean of leaf dry matter content. Our empirical results show that functional diversity and community-weighted means are of secondary importance for explaining changes in ecosystem process rates during tropical forest succession. Instead, simply, the amount of vegetation in a site is the major driver of changes, perhaps because there is a steep biomass buildup during succession that overrides more subtle effects of community functional properties on ecosystem processes. We recommend future studies in the field of biodiversity and ecosystem functioning to separate the effects of vegetation quality (community-weighted mean trait values and functional diversity) from those of vegetation quantity (biomass) on ecosystem processes and services.

• Publisher: Ecological Society of America
• Subject: aboveground biomass / Biodiversity / biodiversity experiment / biodiversity-ecosystem functioning / Biomass / Biomass production / carbon storage / community-weighted mean / Decomposition / Dry matter / dry matter content / Ecological function / Ecological processes / Ecological succession / ecosystem functioning / ecosystem processes / Ecosystems / Environmental changes / field experimentation / Forest ecology / Forest ecosystems / forest succession / Forests / Functional diversity / functional properties / functional traits / land-use / leaf area / Leaf litter / leaf traits / Leaves / Litter / Mexico / neotropical forests / Plant Development - physiology / plant functional traits / plant litter / Plants - classification / Population Dynamics / predict litter decomposition / primary productivity / Productivity / secondary forest / secondary succession / Shifting cultivation / Species / species richness / structural equation modeling / Time Factors / tree productivity / Tropical Climate / Tropical forests / Vegetation / Vegetation effects