Quantifying the Impact of Climate Change and Forest Management on Swedish Forest Ecosystems Using the Dynamic Vegetation Model LPJ-GUESS

Boreal and temperate forests are undergoing structural, compositional and functional changes in response to increasing temperatures, changes in precipitation, and rising CO2, but the extent of the changes in forests will also depend on current and future forest management. This study utilized the dynamic vegetation model LPJ-GUESS enabled with forest management (version 4.1.2, rev11016) to simulate changes in forest ecosystem functioning and supply of ecosystem services in Sweden. We compared three alternative forest policy scenarios: Business As Usual, with no change in the proportion of forest types within landscapes; Adaptation and Resistance, with an increased area of mixed stands; and EU-Policy, with a focus on conservation and reduced management intensity. LPJ-GUESS was forced with climate data derived from an ensemble of three earth system models to study long-term implications of a low (SSP1-2.6), a high (SSP3-7.0), and a very high (SSP5-8.5) emissions scenario. Increases in net primary production varied between 4% and 8% in SSP1-2.6, 21%-25% in SSP3-7.0 and 25%-29% in SSP5-8.5 across all three forest policy scenarios, when comparing 2081-2100 to 2001-2020. Increased net primary production was mediated by a higher soil nitrogen availability and increased water use efficiency in the higher emission scenarios SSP3-7.0 and SSP5-8.5. Soil carbon storage showed small but significant decreases in SSP3-7.0 and in SSP5-8.5. Our results highlight differences in the predisposition to storm damage among forest policy scenarios, which were most pronounced in southern Sweden, with increases of 61%-76% in Business-As-Usual, 4%-11% in Adaptation and Resistance, and decreases of 7%-12% in EU-Policy when comparing 2081-2100 to 2001-2020.