Contributions of a Global Network of Tree Diversity Experiments To

Contributions of a global network of tree diversity experiments to sustainable forest plantations Kris Verheyen, Margot Vanhellemont, Harald Auge, Lander Baeten, Christopher Baraloto, Nadia Barsoum, Simon Bilodeau-Gauthier, Helge Bruelheide, Bastien Castagneyrol, Douglas Godbold, et al. To cite this version: Kris Verheyen, Margot Vanhellemont, Harald Auge, Lander Baeten, Christopher Baraloto, et al.. Con- tributions of a global network of tree diversity experiments to sustainable forest plantations. AMBIO: A Journal of the Human Environment, Springer Verlag, 2015, online first (1), 10.1007/s13280-015- 0685-1. hal-01204232 HAL Id: hal-01204232 https://hal.archives-ouvertes.fr/hal-01204232 Submitted on 23 Oct 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Ambio 2016, 45:29–41 DOI 10.1007/s13280-015-0685-1 PERSPECTIVE Contributions of a global network of tree diversity experiments to sustainable forest plantations Kris Verheyen, Margot Vanhellemont, Harald Auge, Lander Baeten, Christopher Baraloto, Nadia Barsoum, Simon Bilodeau-Gauthier, Helge Bruelheide, Bastien Castagneyrol, Douglas Godbold, Josephine Haase, Andy Hector, Herve´ Jactel, Julia Koricheva, Michel Loreau, Simone Mereu, Christian Messier, Bart Muys, Philippe Nolet, Alain Paquette, John Parker, Mike Perring, Quentin Ponette, Catherine Potvin, Peter Reich, Andy Smith, Martin Weih, Michael Scherer-Lorenzen Received: 31 January 2015 / Revised: 16 June 2015 / Accepted: 27 June 2015 / Published online: 12 August 2015 Abstract The area of forest plantations is increasing part of REDD?. Forest plantations already provide up to worldwide helping to meet timber demand and protect 33 % of the total industrial roundwood volume harvested natural forests. However, with global change, monospecific annually in the world, and are projected to make up as plantations are increasingly vulnerable to abiotic and biotic much as 50 % of the global industrial roundwood produc- disturbances. As an adaption measure we need to move to tion by 2040 (Kanninen 2010). Beyond wood production, plantations that are more diverse in genotypes, species, and plantations also provide a range of other ecosystem ser- structure, with a design underpinned by science. TreeDivNet, vices, including carbon sequestration and water retention a global network of tree diversity experiments, responds to this (Pawson et al. 2013). Moreover, when incorporated into need by assessing the advantages and disadvantages of mixed integrated landscape management, plantations can play a species plantations. The network currently consists of 18 large role in achieving biodiversity conservation objectives experiments, distributed over 36 sites and five ecoregions. by offsetting the need to extract resources from natural With plantations 1–15 years old, TreeDivNet can already forests (Paquette and Messier 2010). provide relevant data for forest policy and management. In Currently, plantation forests are almost exclusively this paper, we highlight some early results on the carbon planted as monocultures (Nichols et al. 2006, Box 1). Yet, sequestration and pest resistance potential of more diverse several reviews published recently provide evidence, from plantations. Finally, suggestions are made for new, innovative both natural forests and plantations that biomass produc- experiments in understudied regions to complement the tion and the delivery of other ecosystem services can existing network. improve with tree diversity (Nadrowski et al. 2010; Scherer-Lorenzen 2014). Furthermore, global change may Keywords Biodiversity experiments Á increase disturbance frequencies and intensities in both Functional biodiversity research Á Plantation forest Á natural forest (Woods et al. 2005) and plantations (Pawson Sustainable forest management Á Ecological restoration et al. 2013), significantly affecting wood supply chains with severe economic consequences (Hanewinkel et al. 2012). Forest plantations that are diverse in genotypes, A GLOBAL CALL FOR SUSTAINABLE FOREST species, structure, and function, should be better able to PLANTATIONS adapt to changing environmental conditions than monocultures (van Hensbergen 2006; Bauhus et al. 2010). This Although the global forest area declined by ca. 13 million calls for the development of novel, more diversified forest ha per year between 2000 and 2010, the forest plantation plantations that can improve plantations’ stability, pro- area actually increased annually by ca. 5 million ha in the ductivity, and delivery of ecosystem services. Since plan- same time period, representing ca. 7 %, i.e., 264 million ha, tations are often established near human settlements, they of the global forest area in 2010 (FAO 2010). Afforestation are the primary window through which society looks at rates may increase further due to incentives for carbon forest management. Changing the way we manage plan- sequestration and the global pledge to protect the remain- tations and setting objectives for them can therefore have ing natural forests of the world against degradation, e.g., as profound and rapid impacts on the social acceptance of Ó Royal Swedish Academy of Sciences 2015 www.kva.se/en 123 30 Ambio 2016, 45:29–41 forestry (Paquette and Messier 2013). It has been noted, long-term silvicultural trials were established to identify however, that foresters currently resist establishing mixed the most productive species and provenances to plant in plantations, in large parts because of the perception that novel forests. The trials were definitely a success for the mixing genotypes and species reduces yield and compli- development of production-oriented management; large- cates forest management operations (Carnol et al. 2014). scale forest plantations were established with fast-growing TreeDivNet, a new global network of tree diversity tree species. The trials were often designed as common experiments, responds to the need for a solid, science- garden experiments comparing the growth and perfor- based framework for documenting and understanding the mance of different species and provenances at one site, i.e., benefits and drawbacks of mixed plantations. In this paper, under similar environmental conditions. Despite the lively we explain the need for new afforestation trials and present debate about the advantages and disadvantages of pure the TreeDivNet network of experimental plantations. We versus mixed forests (even in that early era), most of the show some early results from the network and formulate trials consisted of monocultures or, less frequently, two- suggestions for additional experimental plantations that species mixtures (Scherer-Lorenzen 2014). Presently, may cover existing research gaps. 300 years after von Carlowitz´s proposition of sustainability and given recent advances in biodiversity science (e.g., Cardinale et al. 2012), we need to know which mixtures BOX 1 provide higher levels of biomass production and of other ecosystem services and how environmental conditions Multi-species tree plantations are still relatively rare affect the relationship between tree diversity and forest worldwide, but is this topic important within the functioning, both in space and time. forest research communities and is there an increas- To address these issues, several scientific approaches are ing interest in the last 10 years? We investigated available. Given the long lifespan and size of trees, simu- these questions using the software WORDSTAT 6.0 lation models that predict ecosystem service output along a (Pe´ladeau 2003) by comparing the percentage of range of tree diversities and environmental conditions are abstracts containing the word ‘‘plantation’’ that also an obvious approach. However, such models need param- contained the words ‘‘species mixture, mixed system, eterization, which is an enormous challenge given how mixed plantation, mixed-species plantation or multi- poorly we understand biotic interactions among species. species plantation’’ between the proceedings of the Parameters can be estimated based on experiments or IUFRO World Congresses1 of 2005 and 2014. In the observational studies, but both the types and ranges of tree proceedings of 2014, we found 2426 abstracts of diversities we seek to study are not always present. Still, which 267 used the term ‘‘plantation’’. Of these 267 highly interesting and relevant work has been accom- abstracts, 20 (or 7.5 %) also used at least one of the plished with simulation tools (e.g., Morin et al. 2011). terms referring to mixed plantation mentioned above. Observational studies are invaluable for providing real- In the proceedings of 2005, we found 1454 abstracts world reference data (Baeten et al. 2013), but also have of which 238 used the term ‘‘plantation’’. Of these many drawbacks because tree species composition strongly 238 abstracts, only 1 (or 0.4 %) used at least one of depends on environmental factors or management. Exper- the terms referring to mixed plantation. This clearly iments avoid these issues, but there are still relatively few shows that the interest

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