Assessment of the functional role of tree diversity: the multi-site FORBIO experiment

in Plant Ecology and Evolution (2013), 146(1), 26-35

Context – During the last two decades, functional biodiversity research has provided strong support for the hypothesis that more biodiverse ecosystems have the potential to deliver more and better ... [more ▼]

Context – During the last two decades, functional biodiversity research has provided strong support for the hypothesis that more biodiverse ecosystems have the potential to deliver more and better services. However, most empirical support for this hypothesis comes from simple structured communities that are relatively easy to manipulate. The impact of forest biodiversity on forest ecosystem functioning has been far less studied. Experiment design – In this paper, we present the recently established, large-scale FORBIO experiment (FORest BIOdiversity and Ecosystem Functioning), specifically designed to test the effects of tree species diversity on forest ecosystem functioning. FORBIO’s design matches with that of the few other tree diversity experiments worldwide, but at the same time, the FORBIO experiment is unique as it consists of a similar experimental set-up at three sites in Belgium (Zedelgem, Hechtel-Eksel and Gedinne) with contrasting edaphic and climatological c haracteristics. This design will help to provide answers to one of the most interesting unresolved questions in functional biodiversity research, notably whether the effects of complementarity on ecosystem functioning decrease in less stressful and more productive environments. At each site, FORBIO consists of 41 to 44 plots (127 plots in total) planted with monocultures and mixtures up to four species, selected from a pool of five site-adapted, functionally different tree species. When allocating the treatments to the plots, we maximally avoided any possible covariation between environmental factors. Monitoring of ecosystem functioning already started at the Zedelgem and Gedinne sites and will start soon in Hechtel-Eksel. Multiple processes are being measured and as the trees grow older, we plan to add even more processes. Expected results – Not only basic science, but also forest management will benefit from the results coming from the FORBIO experiment, as FORBIO is, for instance, also a test case for uncommon, not well-known tree species mixtures. To conclude, FORBIO is an important ecosystem experiment that has the potential to deliver badly needed insights into the multiple relationships between biodiversity and ecosystem functioning, which will be valuable for both science and practice. [less ▲]

Assessment of the effects of tree species diversity on forest biodiversity and ecosystem functioning (FORBIO) - Final Report

Report (2010)

Forests are biodiversity hotspots worldwide with 70% of terrestrial biodiversity being included in forested landscapes. However, deforestation, forest degradation and fragmentation lead to an increasing ... [more ▼]

Forests are biodiversity hotspots worldwide with 70% of terrestrial biodiversity being included in forested landscapes. However, deforestation, forest degradation and fragmentation lead to an increasing rate of species extinctions. Hence, predicting the consequences of changes in species numbers, in distribution patterns of taxa, and of shifts in dominance, has become a major challenge for community and ecosystem ecology. However, until now the relationships between biodiversity and ecosystem functioning in forests have been largely underexplored Therefore, the overall aims of the BELSPO cluster project FORBIO are: to review, synthesize and disseminate existing knowledge about the benefits and drawbacks of mixed stands vs monocultures (WP1); and to establish a highly innovative, large-scaled forest biodiversity experiment to evaluate the impact of increasing tree diversity on forest ecosystem functioning (WP2). To achieve the first objective, a so-called ‘white paper’ has been compiled by the FORBIO team members which has been published in Dutch as a special issue of the BosRevue and in French as a special issue of Forêt Wallone. Among stakeholders, many different opinions exist about the functioning of mixed forests and therefore the scientific evidence was confronted with stakeholder perceptions on ecosystem services in mixed forests compared to monocultures. The principal outcome was that stakeholders appear to have quite strong opinions on the functioning of mixed vs monoculture stands, whereas the review of the scientific literature highlighted the lack of specific information on forest ecosystem services in mixed forests compared to monocultures, in particular from studies where confounding factors can be eliminated or accounted for. The second objective was met by establishing two large-scaled tree diversity experiments in Zedelgem (Flanders) and Gedinne (Wallonia). Based on a state-of-the-art experimental design, 32 810 and 33 304 trees of five different species were planted in 42 and 44 experimental plots in Zedelgem and Gedinne, respectively. A third experiment with a similar design will be established in Hecthel-Eksel (Flanders) in 2011. FORBIO’s short-term contributions to sustainable development are mainly related to the fact that the project has introduced the state-of-the-art concepts and empirical support on the various relationships between biodiversity and ecosystem functioning to a large audience of forest owners, managers, users and scientists in Belgium. In the long-run, FORBIO will significantly contribute to a better understanding of the importance of tree species diversity for the functioning of forest ecosystems and the ecosystem services that they provide thanks to the establishment of the two (and soon three) large-scaled tree diversity experiments. Furthermore, the experiments, embedded in the worldwide TreeDivNetwork, will most likely continue to act as an attractor for researchers from Belgium and abroad. [less ▲]