The theoretical and practical significance of tree species and functional diversity in designing novel forest ecosystems

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Natural forest ecosystems worldwide are being gradually eliminated and/or greatly simplified at an alarming rate by direct and indirect human interventions. Remaining natural and managed forests are being impacted by factors associated with global change (invasive species and pests; changing climate). This trend is likely to increase in the future due to increasing human population pressures and accelerating global change. These stresses are even more alarming considering that forests provide habitats for more than 65% of the terrestrial biodiversity and are key providers of many ecosystem services. Yet, compelling scientific evidence now shows that the productivity and resilience of natural and managed ecosystems are greatly dependent on the maintenance of biodiversity and complexity. In this project, we will focus on mechanisms involved in supplying two major forest ecosystem services: primary productivity in terms of wood and soil carbon sequestration. Scientists from 4 Canadian universities (Sherbrooke, Laval, UQAR & UQAM) will work together with collaborators from the US and Poland. The research will compare the role of tree species, phylogenetic and functional trait diversity in (1) maintaining healthy natural and managed forests; (2) contributing to more productive and resilient novel forest ecosystems; and (3) maximizing carbon sequestration. The core approach will be the establishment and monitoring of a series of world-unique experimental high-density single and mixed native and exotic tree species plantations in three different regions of north-eastern America and in one region of Poland. The project will evaluate how various mixtures of native and exotic tree species affect: (1) above and below-ground biomass and root distribution; (2) fine-root growth, morphological and architectural dynamics; (3) C, N, P and base cycling, storage and leaching in soils and decomposition; and (4) trophic complementarity. The results of this project will provide both government and private stakeholders the necessary knowledge to develop well-informed innovative policies and practices regarding the use of mixed species plantations and exotics as part of sustainable forest management.