Natural conditions for heliophilous tree-species following forest dieback in temperate zone after periglacial habitats

Abstract

Widespread forest dieback following a series of exceptionally dry seasons has made restoration by relic heliophilous tree-species uncertain. Using logistic regression, we identified conditions suitable for relic Norway spruce (Picea abies /L./ Karst.), Scots pine (Pinus sylvestris L.), European larch (Larix decidua Mill.), birches (Betula sp.), poplars (Populus sp.) and willows (Salix sp.) by comparing the relief and bedrock under stands that died abruptly between 2018 and 2020 at temperate zone after periglacial habitats of the Czech Republic. Extent of forest dieback was determined through automated object analysis on the basis of vectorised Planet Scope and Sentinel-2 satellite images. The object analysis consisted of mainly spruce stands and dieback indicated by a deep inter-year decrease in the vegetation indices. The overall occurrence of tree-species in pure or mixed stands was determined from a polygon geodatabase of forest management plans, while growth condition types were determined by overlaying biogeographically subdivided polygons. Dead forests provided suitable conditions for mixed conifer, birch, and poplar stands on 64.4 % of the greywackes, acid metamorphites, and waterlogged sediments on broken plateaus, depressions, and slopes. In comparison, pure stands of relic tree-species can cover 35.6 % of dead forest area. Restoration of mixed forests differenting over a range of growth conditions seems to be suitable for adaptation to climate change impacts.