Climate change and management of forest biodiversity: predicting the impacts of climate matching strategies on plant-herbivore-enemy interactions.

The world is experiencing rapid climate change with a predicted rise in global average temperatures of 2-5 deg C over the next 50 years. Among a range of predicted ecosystem impacts, one already documented is a temperature-driven shift in species distributions & within-species genetic diversity in many mobile animal taxa. However, long-lived plants, including keystone forest trees, disperse slowly & cannot adapt to rapid climate change within the lifespan of individuals. Forests are likely to be among the first habitats impacted by climate change, a realisation driving the search for appropriate management responses. Current practice involves replanting every 50 - 100 years with locally sourced seed populations (or provenances). However, as climates change, local tree phenotypes are predicted to become increasingly poorly adapted to local conditions. One strategy that has been proposed to mitigate this impact in forestry is replanting with 'climate matched' tree populations, i.e. to identify areas in Europe that experience now the climate predicted for the UK 50 - 100 years from now, & to use provenances from these locations in replanting. Though intuitively attractive, climate matching is not without risk. Planting with non-native tree provenances may disrupt highly-specific interactions between local trees and associated animals, potentially undermining ecosystem processes including natural pest control valued at billions of dollars annually. Further, non-native trees are likely to respond to northern seasonal patterns in such a way that their usual timing of key biological processes, particularly the timing of production of new leaves in spring (or budburst), is disrupted. This in turn could have major consequences for dependent animals - particularly herbivorous insects and the predators that depend on them (including many song birds). This project addresses the key question for climate matching: what is the impact of growing non-native oak provenances, with different biological traits to native oaks, on the biodiversity of herbivores and predators? The work contributes to predicting the biodiversity consequences of climate change, directly addressing Topic 3 (points 2 & 3) in the EHFI call & testing hypotheses of general relevance in climate change ecology. We will examine these issues in the sessile oak, Quercus petraea, a keystone species for hundreds of associated animal species in Britain and continental Europe. We will make use of a large-scale experiment in France that recreates the impact of climate matching by growing sessile oaks from many parts of Europe and Asia Minor together in a single trial, all exposed to the same community of local herbivores and predators. As expected in climate matching, oaks imported from differing latitudes open their leaves at very different times, some earlier and some later than local oaks. We will examine the biodiversity consequences of variation in this and other biological traits by surveying the insect herbivores and their wasp natural enemies in 20 provenances capturing the full biological and genetic diversity of sessile oak. Specifically, we will test how biodiversity changes in response to differences in traits (including timing of budburst) between local and non-native oaks. We aim not only to test a range of hypotheses of general importance in climate change ecology, but also to generate statistical relationships that allow forestry managers and other stakeholders to predict likely biodiversity consequences of climate matching as a strategy. This project addresses the stated aims of the CEH and NERC missions to predict the regional & local impacts of environmental change from days to decades, to quantify the impact of environmental change on natural resources (Challenge IV, CEH Science Strategy), & to identify strategies & control measures to mitigate impacts of environmental change on ecosystems, ecosystem services (Challenge VI).