Climate envelope models for temperate trees in insular sector of the Russian Far East: current and future distribution of Kalopanax septemlobus (Araliaceae) and Phellodendron amurense var. sachalinense (Rutaceae)
Kirill A. Korznikov
Botanical Garden-Institute FEB RAS, Vladivostok, 690024, Russia
I modelled distribution of temperate trees species Kalopanax septemlobus (KS) and Phellodendron amurense var. sachalinense (PAS) in Sakhalin Island and the Kuril Islands (south boreal zone generally) according to climate change scenario for the time period until 2050 year. Climate envelope models was constructed based on actual species locations (n=38 for KS, n=29 for PAS) and WorldClime v.1.4 bioclimatic data (30 arcsin resolution) using the maximum entropy technique (MaxEnt v.3.3). I used six bioclimatic variables: mean annual temperature, Kira’s warm index, mean minimal temperature of coldest month, index of continentality, total precipitation in months with mean temperature below 0 °С, total precipitation in coldest quarter. I used RCP2.6 and RCP8.5 scenarios of global warming based on CCSM4 (Community Climate System Model). According to permutation importance and jackknife test Kira’s warm index is the most influential predictor for species distribution models, followed by total precipitation of the coldest quarter. Current climate models predict 1.27% (~1 100 km2) of islands territory for KS habitats and 2.55% of territory for PAS habitats with 50% minimum threshold probability of suitable habitats. Range of both species would begin to expand north in future. Models based on RCP2.6 projection (increase of annual mean temperature in region on 3.9 °C) predict 9.55% of territory for KS habitats and 14.65% of territory for PAS habitats. Models based on RCP8.5 projection (increase of annual mean temperature on 5.2 °C) predict 45.86% and 66.24% of territory for species habitats respectively. The trees regeneration niches are necessary to expansion of both species in suitable climate condition. The large-scale windfalls may promote ecological niches for temperate trees expansion in region.