The capacity of a forest ecosyste
m to recover following
major disturbances depends on the regeneration characteristics of the species and the environ
ment at the ti
me of establish
ment, resulting fro
m several interacting biotic and abiotic factors. At cli
matically stressed sites
major drivers of recruit
ment are the presence of a seed source and the availability of ¡®safe sites¡¯ for ger
mination, particularly in the harsh conditions resulting after a stand-replacing wildfire. Post-fire rehabilitation and restoration treat
ments can produce a deep ecological i
mpact on recruit
ment processes, acting on biotic legacies and altering the variety and
abundance of
microsites.
Two common post-fire management strategies, salvage logging and the absence of any post-fire intervention, were contrasted in a burned area located in Aosta Valley (North-Western Italy) to identify main environmental variables affecting seedlings and to quantify the effect of shelter elements on tree recruitment. Our hypothesis is that post-fire burned wood management may greatly affect microhabitat suitability for seedling survival in a dry mountain m>Pinus sylvestrism> forest.
Regeneration density five years after the fire was still low, even though tree species recruitment started immediately following the disturbance. Differences in species composition were found among the investigated treatments. Regeneration density and diversity were positively associated with deadwood. An exception was represented by m>Populus tremulam>, regenerating mostly vegetatively, whose behaviour differed from the other tree species. Ground cover conditions contributed to patterns of seedling occurrence. The strong spatial association of seedlings with deadwood suggests that deadwood produces microsites that enhance establishment of regeneration. The relationship between nurse deadwood elements and regeneration was found to be highly anisotropic, as a consequence of the higher protection from radiation and reduced soil moisture loss in the shady sides of the shelter element. In this context post-fire management, particularly when removing burned wood, should be implemented with an understanding of its potential to affect the capacity of the ecosystem to restore, influencing both directly and indirectly recruitment.
