Persistence of boreal forest epiphytes under alternative objective-driven forest management scenarios

Abstract

Epiphytes need to colonize new suitable host trees before their existing host trees disappear in order to persist in forest landscapes. Thus, their persistence may be threatened by accelerated dynamics of intensive forest management [1], especially if suitable host trees will be scarcely located [2].

Wood production is a key global provisioning ecosystem service. In the European Union, the bioeconomy policy guides forest management for the provision of forest products and ecosystem services to meet global, EU wide and national demands. At the same time, the EU Biodiversity Strategy sets targets for the sustainable management of forests to maintain the persistence of species. It is therefore important to identify forestry practices that can reconcile the contrasting objectives of providing high forest product yields while also preserving forest biodiversity.

We studied how alternative, objective-driven forest management scenarios affect the persistence and metapopulation dynamics of epiphytic lichens and bryophytes in boreal forests. We fitted spatially explicit colonization-extinction models for six bryophyte species of varying host tree preferences and one epiphytic lichen (Lobaria pulmonaria) using landscape-scale data from north-eastern Finland. We simulated their metapopulation dynamics for 100 years into the future assuming different forest management scenarios created for a 66 000 ha study landscape in northern Sweden. The forest management scenarios varied in terms of tree species composition, management and retention practices and were constructed based on alternative criteria, such as the projected wood product demand under different future scenarios of Shared Socioeconomic Pathways [3] for the European Union.

Our results show how forest variables and connectivity to potential dispersal sources explain colonization and extinction dynamics and persistence for different forest epiphytes. Thus, our results pinpoint combinations of forestry and conservation strategies that best support the long-term persistence of species while meeting the defined forestry objectives. Altogether, our results help to reconcile forestry and biodiversity conservation in boreal forests.

The work is part of the BiodivERsA project GreenFutureForest.

References: 1. Belinchón R, Harrison PJ, Mair L, Várkonyi G & Snäll T. 2017. Local epiphyte establishment and future metapopulation dynamics in landscapes with different spatiotemporal properties. Ecology 98:741–750. 2. Johansson V, Ranius T & Snäll T. 2012. Epiphyte metapopulation dynamics are explained by species traits, connectivity, and patch dynamics. Ecology 93:235–241. 3. Riahi K, van Vuuren DP, Kriegler E… & Tavoni M. 2017. The Shared Socioeconomic Pathways and their energy, land use, and greenhouse gas emissions implications: An overview. Global Environmental Change 42:153–168.