Drivers and Mechanisms of Ecosystem Multifunctionality in Secondary Tropical Forests

Abstract Tropical forests provide vital ecosystem functions and services, yet global change is intensifying disturbance regimes and expanding the extent of young secondary forests. The question is to what extent these young forests recover ecosystem multifunctionality and under which conditions recovery proceeds faster. Here, we analyze the drivers and mechanisms that shape a comprehensive set of 16 ecosystem functions related to carbon, water, and nutrient cycling. We established plots in 36 young secondary forest stands (2.3–3.6 years since agricultural abandonment) in dry and wet regions in Ghana. In each plot, we measured eight forest attributes related to structure, diversity, and functional composition, six soil physical and chemical properties, and quantified 16 ecosystem functions to test how environmental conditions and forest attributes shape ecosystem functioning using structural equation modeling. Climatic wetness and soil conditions most strongly influenced ecosystem functions (9 functions each), followed by structure (8), diversity (5), and functional composition (4). The relative importance of these drivers and mechanisms varied across cycles: The carbon cycle was most influenced by forest attributes, whereas the water and nutrient cycles were primarily shaped by environmental conditions, with forest structure additionally shaping nutrient cycling. Hence, in early successional ecosystems, ecosystem multifunctionality is more strongly shaped by environmental conditions and vegetation quantity than by biodiversity, and different conditions are needed for the recovery of different cycles. When previous land use intensity has been low, forest recovery can proceed fast, and natural regeneration offers a scalable, low-cost opportunity for restoring multifunctionality, especially in wet tropical forests.