Fjölrit RALA - 05.12.1999, Qupperneq 40

38
Agropastoralism and fires in the Mediterranean
Correlation between stocking rate (SR) and bumed surface (S) being very low, it
can be inferred that the use of fire was mainly related to the clearance of the existing
pastures and to the creation of new ones independent of stocking rate. Stocking rate
(SR) is mainly linked with soil productivity: on irrigated soil, SR can be 20 sheep ha'1
with no need to use fire as an agronomic practice; on the contrary, in areas having a
SR of 1 sheep ha_l fire can be intensely used.
The correlations mentioned above confirm the close relationship between number
of fires or extension of bumed areas and sheep number rather than stocking rate.
In addition the number of outbreaks (NO) showed a low correlation with bumed
surfaces, thus confirming the high incidence of catastrophic events, while the positive
correlation with UR (0.223) highlights the socioeconomic component in fire phe-
nomenon.
The regression between sheep number and bumed surface (Figure 2) showed that to
each sheep head corresponds 0.13 ha of bumed area, explaining 35.1% oftotal vari-
ance.
Y=737.141 + 0.13403DX
R-Squared=0551
SN
Figure 2. The relationship between sheep number and burned surface (ha) between 1980 and 1990
in Northern Sardinia, Italy.
The regression between sheep number change and bumed surfaces (Figure 3)
showed the presence of tw’o almost independent components: the first one related to
sheep number change (regression line) and the second one to all the other factors in-
fluencing the phenomenon (broken line), partially excluding SN as a consequence of