Temporal and Spatial Change in Diameter Growth of Boreal Scots Pine, Norway Spruce, and Birch under Recent-Generation (CMIP5) Global Climate Model Projections for the 21st Century

Abstract

Abstract:We investigated how climate change affects the diameter growth of boreal Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), and silver birch (Betula pendula Roth) at varying temporal and spatial scales. We generated data with a gap-type ecosystem model for selected locations and sites throughout Finland. In simulations, we used the current climate and recent-generation (CMIP5) global climate model projections under three representative concentration pathways (RCPs) forcing scenarios for the period 2010-2099. Based on this data, we developed diameter growth response functions to identify the growth responses of forests under mild (RCP2.6), moderate (RCP4.5), and severe (RCP8.5) climate change at varying temporal and spatial scales. Climate change may increase growth primarily in the north, with a clearly larger effect on birch and Scots pine than Norway spruce. In the south, the growth of Norway spruce may decrease largely under moderate and severe climate change, in contrast to that of birch. The growth of Scots pine may also decrease slightly under severe climate change. The degree of differences between tree species and regions may increase along with the severity of climate change. Appropriate site-specific use of tree species may sustain forest productivity under climate change. Growth response functions, like we developed, provide novel means to take account of climate change in empirical growth and yield models, which as such include no climate change for forest calculations.

Effects of using certain tree species in forest regeneration on regional wind damage risks in Finnish boreal forests under different CMIP5 projections

“…A gap-type forest ecosystem model SIMA (Kellomäki et al 2005(Kellomäki et al , 2008(Kellomäki et al , 2018 was used to simulate the regeneration, Table 1 Simulation layout with stand and site conditions, climate projections and management activities (same simulation layout was used also in the study of Alrahahleh et al 2018)…”

“…The species-specific response to the temperature sum was modeled for the main Finnish boreal tree species, based on a downward-opening symmetrical parabola (Kienast 1987;Nikolov and Helmisaari 1992;Kellomäki et al 2008Kellomäki et al , 2018. This was done by assuming that the minimum and maximum values of the temperature sum define the geographical distribution of each tree species throughout the boreal zone (Table 1).…”

“…Climate change is expected to increase the productivity of forests, especially in the northern boreal zone, due to improving growing conditions (Bergh et al 2003;Briceño-Elizondo et al 2006;Koca et al 2006;Kellomäki et al 2008Kellomäki et al , 2018Poudel et al 2011). At the same time, it may decrease the productivity in the southern boreal zone (Koca et al 2006;Kellomäki et al 2008Kellomäki et al , 2018Reyer et al 2017). The responses of forests to climate change may differ greatly at the regional level.…”

“…This is related to differences in the prevailing environmental conditions (climate, site), current forest structure (age, species) and forest management regimes (Bergh et al 2003;Briceño-Elizondo et al 2006;Garcia-Gonzalo et al 2007;Kellomäki et al 2008;Lindner et al 2010;Alrahahleh et al 2018). Particularly under severe climate warming, the growth and success of Norway spruce are expected to decrease in Finland, especially on southern upland forest sites, if the growing conditions (temperature and water availability) become suboptimal for its growth (Briceño-Elizondo et al 2006;Jyske et al 2010;Kellomäki et al 2018;Ruosteenoja et al 2018). Increasing forest disturbances, such as wind damage, may also amplify, or even cancel out, any expected increases in the productivity of forests under changing climate (Kellomäki et al 2008;Reyer et al 2017).…”

“…In this context, we studied how the use of certain tree species in forest regeneration could affect the regional wind damage risks to Finnish boreal forests under the current climate and recent-generation global climate model (GCM) predictions (i.e., 10 GCMs of CMIP5, with wide variations in temperature and precipitation; Ruosteenoja et al 2016), using RCP4.5 and RCP8.5 over the period 2010-2099. The study employed forest ecosystem (SIMA; Kellomäki et al 2005Kellomäki et al , 2008Kellomäki et al , 2018 and mechanistic wind damage (HWIND; Peltola et al 1999b) model simulations on upland National Forest Inventory (NFI) plots throughout Finland. In a baseline management regime, forest regeneration was performed by planting the same tree species that was dominant before the final cut.…”