Impatto dell’erbivoria causata da ungulati sulla rinnovazione naturale dell’abete bianco (Abies alba M.) al limite Sud del suo areale in Europa e nel Mediterraneo
Author(s)
Scarfò, Francesco
Date Issued
March 11, 2011
Type
Doctoral Thesis
Abstract
The Mediterranean Basin is considered one of the 25 biodiversity hotspots of the
planet. The silver fir populations of the Calabrian Serre are located to the south limit
of their distribution in Europe and in the Mediterranean Basin and they are
considered as relicts of high genetic variability.
Silver fir has an important economic and ecological role for the local populations and
for this reason it is important to: 1) analyze the disturbance that threaten its
abundance and the distribution; 2) analyze the degradation phenomena that can alter
the functionality. The natural regeneration of the white fir is subject to the impact of
the herbivores in everything of its distribution area but the studies about these effects
are scarce for the area of the Mediterranean Basin. The purpose of this study is to
assess the impact caused by disturbances on the silver fir natural regeneration in the
short period and therefore to asses: 1) the mortality induced by the ungulates (MIU)
in relationship to the natural mortality (MN); 2) the ungulate presence index in
relationship to the MIU; 3) the MIU with the purpose to implement a model for the
management in the short period and for the planning in the long period; 4) the
degrade status appraising the concept of threshold within which it is possible to
distinguish conditions of degrade from conditions of non degrade.
The disturbance magnitude and frequency was assessed using a random block with
two replicas experimental design. The control (EE) excluded seedlings and two
theses: non-excluded seedlings low disturbance (NEE1) non-excluded seedlings high
disturbance (NEE2). Parametric and non parametric test was used to assess the
differences. A survival logistic model of MIU model was carried out using the data
collected in the monitoring plots.
Ungulate presence in the study area has an important negative effect on the natural
regeneration and seedlings survival also raises negative effects on the principal
ecological functions of the silver fir woods. This effect was higher in the nonexcluded
areas in which the MIU was higher than the MN. In our study forest the
time necessary to attain a height threshold to escape from ungulates herbivores (150
cm height) is retarded for about 30 year in the non-excluded seedlings. Ungulates are
a major factor hindering the natural regeneration and conservation of the silver fir in
the southern limit of its distribution in Europe and in the Mediterranean Basin.
Additional information
Dottorato di ricerca in Scienze e tecnologie per la gestione forestale e ambientale
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