Remote sensing-based forest modeling reveals positive effects of functional diversity on productivity at local spatial scale

Abstract

SummaryForest biodiversity is critical for many ecosystem functions and services at plot scale, but it is uncertain how biodiversity influences ecosystem functioning across environmental gradients and contiguous larger areas. We used remote sensing and process-based terrestrial biosphere modeling to explore functional diversity–productivity relationships at multiple scales for a heterogeneous forest site in Switzerland.We ran the biosphere model with empirical data about forest structure and composition derived from ground-based surveys, airborne laser scanning and imaging spectroscopy for the years 2006–2015 at 10×10-m spatial resolution. We then related the model outputs forest productivity to functional diversity under observed and experimental model conditions.Functional diversity increased productivity significantly (p < 0.001) across all simulations at 20×20-m to 30×30-m scale, but at 100×100-m scale positive relationships disappeared under homogeneous soil conditions.Whereas local functional diversity was an important driver of productivity, environmental context (especially soil depth, texture and water availability) underpinned the variation of productivity (and functional diversity) at larger spatial scales. Integration of remotely-sensed information on canopy composition and structure into terrestrial biosphere models helps fill the knowledge gap about how plant biodiversity affects carbon cycling and biosphere feedbacks onto climate over large contiguous areas.