Agriculture Reference
In-Depth Information
Figure 2. Map of the SADIE index of clustering of the
Stipa tenacissima
tussock cover and soil depth
assessed in a 100 m
2
plot (positive and negative values mean patch and gaps zones respectively, see
Perry et al. 1999). The spatial pattern of both variables is assessed with the SADIE index of
aggregation. (I
a
) in the plot (the reader is referred to Maestre and Cortina 2004, for a detail description
of the SADIE method in semiarid steppes) in zones close to the
S. tenacissima
stands I (A) and III (B)
(see Table 2). I
a
= SADIE index of aggregation, where the clumped, random and regular spatial pattern
is defined when: I
a
> 1(*), I
a
≈1 (n.s.) and I
a
< 1 (*) respectively. * and n.s. mean significant values (at
p
< 0.05) and no significant values (
p
> 0.05) respectively assessed by a permutation test.
Figure 3.
Stipa tenacissima
tussocks belonging to stand III in the upper part of the assessed micro-
basin. The arrow underlines the rock outcrop in this area.
