Detecting the imprints of past clear-cutting on riparian forest plant
communities along a Mediterranean river
Abstract
In riparian forests, clear-cutting causes long-lasting changes in both
riparian and aquatic biota. In this work, we examined if past
clear-cutting events occurred at different times have imprints on
riparian forests in a Mediterranean river in central Italy. We carried
out a randomized, plot-based vegetation survey of riparian forests in
systematically sampled 500 m-long sectors along the whole river,
dividing the riparian zone into two internal and two external strips.
From historical aerial photos, past clear-cutting events within plots
were detected and classified in age classes: i) cut in the past 8 years
(recent); ii) cut between 8 and 19 years ago (intermediate); iii) no
signs of clear-cutting in the last 19 years (distant). We analyzed the
responses of vegetation to clear-cutting and strip position. Alien
species richness increased and woody species richness decreased in
recently clear-cut areas compared to those with a distant clear-cutting
event. Moreover, recently cut woods showed an increase in alien and
synanthropic species. Intermediate clear-cut areas had higher levels of
invasion by alien species compared to areas with distant cut. Riparian
forests of internal strips are impacted by clear-cutting, but seem to
recover in 8-19 years thanks to their natural resilience. Conversely,
recent or intermediate clear-cutting events did not affect any of the
investigated vegetation attributes in the external strips since such
forests were already invaded by Robinia pseudoacacia after human
disturbance. Our results confirm that clear-cutting events can have
long-lasting effects on Mediterranean riparian forests, confirming the
vulnerability of river ecosystems to clear-cutting and suggesting the
need for more caution in management practices to improve the
conservation status of riparian forests.