Resurgence of warmth-demanding tree species and a common pending thermophilization in subalpine and northern boreal Sweden-an ecological signal of post-Little Ice Age climate improvement

Largely consistent with general predictions and earlier empirical studies, it appears that post-Little Ice Age climate warming has started to affect large-scale biogeographic patterns in northern Sweden. Long-term monitoring subalpine adjacent regions reveals sparse spread of broadleaved thermophilic tree species. Saplings Quercus robur, Ulmus glabra, Acer platanoides, Alnus glutinosa Betula pendula have responded recent by jump-dispersal the order 50-300 km northwards 500-800 m upwards, relative their natural range limits. Consistent treeline rise boreal species, thermophilies reinvaded where they grew during warmest phase Holocene, 9500-8000 years ago, but were subsequently extirpated Neoglacial cooling. Confined past 20 or so, unique observations termophilies comply background data, i.e. all seasons. These results may contribute more realistic vegetation models stressing distributions certain plant species are able track without substantial migrational lag. Hitherto, evolution appear be well within frames dynamics postglacial era, although mechanisms differ.