Increasing human modification of forest landscapes leads to biodiversity loss and ecosystem degradation, particularly in the tropics. Ambitious programs to restore ecosystems are on the way, but most restoration pledges rely on monospecific tree plantations that fail to provide ecological and social benefits. While the potential for increasing tree diversity to restore ecosystem structure and functioning and to provide key ecosystem services is increasingly recognized, a rigorous evaluation of this potential at the pan-tropical scale is missing.
The overall objectives of the ReDiv project are to assess the effect of tree diversity on stand structural complexity and productivity across different contexts in the (sub)tropics and to facilitate the monitoring of forest structural integrity.
To achieve this objective, we will first take advantage of 12 tree diversity experiments established in the tropics as part of the largest network of biodiversity experiments worldwide TreeDivNet.

First, we will use a terrestrial laser scanner and a drone to measure stand structural complexity (SSC), i.e. the three-dimensional distributional patterns of trees and their canopies. By comparing with existing estimates of reference SSC in nearby old-growth forests, we will develop indicators of forest structural integrity that will be tested across the different tree diversity experiments. Next, we will use existing tree inventory data from the 12 experiments to systematically quantify ground-based SSC and primary productivity.

This will allow us, for the first time at such worldwide pantropical scale, to :

• compare ground-based and remotely-sensed measures of SSC along a gradient of tree diversity
• quantify the strength and shape of the relationships between tree diversity, SSC and productivity and associated benefits in terms of wood production or carbon storage and forest structural integrity
• quantify the context-dependency of these relationships, in particular the influence of the environmental conditions such as climate, soil and topography, or human interventions affecting planting density, plantation age or land-use history
• infer conditional causality underlying the tree diversity-productivity relationship via changes in SSC under specific contexts.

We will transfer the acquired knowledge to the scientific communities and targeted stakeholder groups with dedicated workshops.
The expected impacts are threefold:

• address future avenues in the field of research on biodiversity and ecosystem functioning relationship related to scaling-up, context-dependency and representativeness
• develop the application of terrestrial laser scanning and drone imagery with an indicator of forest structural integrity
• provide knowledge relevant for existing tropical forest landscape restoration projects.

The methodology is divided in three work packages (WP):

• WP1 focuses on data collection. We will measure stand structural complexity from terrestrial laser scanning and drone-based imagery in the experimental sites and nearby old-growth forests. We will also compile existing dataset of tree inventories to quantify ground-based stand structure and productivity.
• WP2 focuses on data analysis. We will compare ground-based and remotely-sensed methods. We will quantify the relationship between stand structural complexity, productivity and tree diversity within and across experimental sites, quantify the context-dependency of these relationships and analyze conditional causal influences.
• WP3 focuses on knowledge transfer and outreach.

Funding and Partners
The project is funded by the Swiss National Science Foundation (SNSF)

Principal investigator

• Clara Zemp, Conservation Biology Lab, Université de Neuchâtel, Switzerland

Employees

• Akshay Bharadwaj Munjurpet Balaji, Conservation Biology Lab, Université de Neuchâtel, Switzerland
• Magnus Onyiriagwu, Conservation Biology Lab, Université de Neuchâtel, Switzerland

Project partners

• Luis Abdala Roberts , Universidad Autónoma de Yucatán, Campus de Ciencias Biológicas y Agropecuaria, Mexico
• Chengjin Chu , MAPPING, Sun Yat-sen University, China
• Gislene Ganade , Restoration Ecology Lab, Universidade Federal do Rio Grande do Norte, Brazil
• Joannès Guillemot , UMR Eco&Sols INRA, France
• Jefferson S. Hall , Smithsonian Tropical Research Institute, United States of America
• Bruno Herault , Direction régionale Afrique de l'Ouest Forêt et Savane humide, CIRAD (Recherche agronomique pour le dévlpt), Ivory Coast
• Holger Kreft , Biodiversity, Macroecology & Biogeography, University of Göttingen, Germany
• Bart Muys , Department of Earth and Environmental Sciences, University of Leuven, Belgium
• Catherine Potvin , Neotropical Ecology Lab: Science for Empower, McGill University, Canada
• Goddert von Oheimb , Biodiversity and Nature Conservation, Technical University Dresden, Germany

Extra information

Extra information can be found here.