Regional Implications: timber yield and conservation concerns
Our results imply that the composition of mid-altitude, monospecific
spruce forests will become increasingly mixed over the coming decades
under rapid high-altitude warming (Beniston, Diaz and Bradley 1997).P . abies comprises the majority of roundwood timber supply
in many European countries, with population sizes bolstered by
continental reforestation efforts since the 1950s and a longstanding
preference for Picea lumber over products from mixed-deciduous
forests (Fanta 1997). Picea is increasingly regarded as an
unsustainable timber-species choice, due to high drought susceptibility
and worsening spruce beetle outbreaks (Hanewinkel et al. 2013). In these
cool-humid Carpathian Picea forests, moisture sensitivity is
somewhat higher in southern locations, but the majority of these sites
have actually increased in productivity over 1980-2010 (Schurman et al.
2019). However, our results imply that managers in the region wishing to
maintain monospecific Picea stands will battle against improved
growing conditions for species like Fagus sylvatica that are
likely to outcompete Picea .
The Carpathians are among Europe’s most ecologically pristine
ecoregions. In fact, sampling within fragments of primary forest
throughout the Carpathians provided the rare opportunity to study a
naturally occurring low-altitude range limit of Picea abies in
Europe, where intense management has otherwise led to an artificial
proliferation of Picea at low altitudes. The unique structural
characteristics of these monospecific Picea forests, for example,
disturbance patches generated by spruce beetle outbreaks, are crucial
habitat elements for multiple species of high conservation value
(Mikolaš et al. 2017). Critically, alpine areas conducive to
monospecific Picea forests are shrinking, and the likely
encroachment of low altitude tree species implies major changes to the
variety of habitats found in these forests (Dirnböck et al. 2011).
Determining whether species associated with monospecific spruce forests
can adapt to forthcoming changes in forest composition emerges as a
critical conservation priority.