BACKGROUND

Forests harbor between 50% and 90% of Earth's terrestrial species and deforestation is therefore the greatest single driver of species extinctions. According to FAO, around 13 million ha of forest are lost annually, with no sign of decreasing rate of deforestation. No less than 12% of the world's species of plants, 44% of birds, 57% of amphibians, 75% of mammals and 87% of reptiles, would be then threatened by forest decline. And yet, since the seminal work of the Millennium Ecosystem Assessment (MEA), it is now widely acknowledged that biodiversity provides many ecosystem services, which are "the benefits human populations derive, directly or indirectly, from ecosystem structures and functions". Ecosystem services are often classified into four categories (MEA): provisioning services (e.g. fiber, fuel), regulating services (e.g., climate regulation), cultural services (e.g. recreational enjoyment) and supporting services (e.g. nutrient cycling). Human dependence on ecosystem services from forests is a key element of the new Sustainable Development Goals of the United Nations and the Conference on Climate Change in Paris (COP 21) is expected to further underline this dependency. The on-going biodiversity loss thus raises concerns that the functioning and stability of forest ecosystems might be affected and the provision of ecosystem services compromised. Recent studies suggest that these negative effects of biodiversity loss could be of a comparable magnitude to those of climate change and worth billions of dollars.

Mainly for logistical reasons, functional biodiversity research in terrestrial systems has been mostly conducted in grasslands until recently. Forest ecosystem functioning and the role biodiversity plays remain poorly understood despite their global importance. Contrasting results have been observed with positive effect of forest biodiversity on stand productivity, resistance to pests and leaf litter decomposition.   Other ecological functions such as those related to biogeochemical cycling, may be less sensitive to changes in tree diversity and are more strongly controlled by site conditions, although recent conceptual advances related to functional trait diversity have enabled better understanding of these effects. The evidence also differs among forest types with better evidence from the tropics than in boreal forests, for example. Furthermore, the relative sensitivity of ecosystem services to different components of forest biodiversity (species richness, functional, phylogenetic or structural diversity) is also poorly known. Finally, few previous studies have focused on the measurement of more than a single ecosystem service at a time, hence precluding the analysis of possible trade-offs/complementarities/synergies among multiple ecosystem services.

OBJECTIVES

The main goals of the CoBES Task Force is therefore to gather the available knowledge on the effects of forest biodiversity on ecosystem services provisioning in managed forests, in order to:

• provide forest managers with relevant information for improving the sustainable management of their forests and inform policy-makers;
• identify new priority research avenues for the IUFRO community, including how other environmental factors, such as climate change and invasive species, influence biodiversity - ecosystem services relationships;
• inform policy makers of the cross-sectoral importance of ecosystem services from forests.

In particular the objectives of CoBES are to:

• develop literature reviews and meta-analyses to better quantify the effect of forest biodiversity on single and multiple ecosystem services;
• highlight the fundamental ecological mechanisms underlying the relationship between forest biodiversity and ecosystem services;
• propose a conceptual framework for designing mixed forest plantations;
• reinforce the cooperation amongst IUFRO divisions in order to cover the largest array of forest ecosystem services and their dependency on forest biodiversity;
• improve the links between IUFRO and the main actors in the field of biodiversity and ecosystem services, i.e. the International Platform on Biodiversity and Ecosystem Services (IPBES), EcoSERVICES of DIVERSITAS, Future Earth and IUCN.

PLANNED ACTIVITIES

In line with our main objectives the CoBES Task Force will organize the following five activities, in its first term of two years (2015-2017):

• Develop and manage a database of IUFRO colleagues working on relationships between forest biodiversity and ecosystem services;
• Provide scientific syntheses and meta-analyses to estimate the overall effect of forest biodiversity on a series of ecosystem services and their synergies or trade-offs.
• Publish a special issue of the journal ‘Biodiversity and Conservation' with papers on the topic "Forest Biodiversity and Ecosystem Services".
• Produce an opinion paper about how to design mixed planted forests so as to sustain productivity while supporting other services.
• Organize joint meetings or conferences between IUFRO working parties and in cooperation with international initiatives such as IPBES.