Walia Special Edition on the Bale Mountains (2011) - Zoologische ...

The three glades in the middle stratum had more variable land use histories, with two of the
three previously supporting small settlements with permanent grazing. Currently, only one of the
three glades is permanently grazed and associated with a settlement.
The glades in the lowermost stratum have a longer history of permanent grazing and
settlement than those at higher altitudes. We were unable to get historical data for Totani; this glade
differs in appearance from Ogate and Addeye, in that it is located on a freely-drained hill with rocky
outcrops rather than a flat, water-logged plain. While the vegetation composition is thought to be
relatively stable in the glades in this stratum, they are thought to have increased in size over the past
30 y.
Soil properties
In the glades, soil pH, total exchangeable bases and base saturation were negatively correlated with
altitude (in all cases with r > 0.8, p < 0.01) and positively correlated with one another (r > 0.9, p <
0.001). These three properties, along with cation exchange capacity, differentiated the glade soils
from the adjacent forest soils (Table 2), being higher in all cases in the forest soils (paired t tests,
p < 0.05). The other variables measured did not show an association with altitude, nor consistent
differences in glade and forest soils.
Soils at the higher altitudes tended to be free draining, both in the glades and the adjacent
forests. At the lower altitudes, the glades tended to be waterlogged or poorly drained (Table 2); the
forest soils in S-1850 and S-1750 are freely drained. The soils in the glades at the higher altitudes
were characterized by tunnelling, whereas at the lower altitudes tunnelling was absent. The soil
profile data are presented in the Appendix.
Vegetation
Species richness measured as morpho-species increased with altitude (Table 3, r = 0.79, P = 0.02,
N=8). The maximum value recorded was 15.2 morphospecies m-2 in Arrawa and the minimum in
Totani (5.6 morphospecies m-2 ). The pattern was strongly influenced by dicot species richness;
monocot species richness appeared unrelated to altitude. These patterns hold even if one examines
the permanently grazed and seasonally grazed glades independently.
<strong>Walia</strong>-<strong>Special</strong> <strong>Edition</strong> on the Bale Mountains 136