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

from each plot were sorted into morpho-species and counted. Morpho-species were categorized into
dicots and monocots and species richness by morpho-species was calculated for each site. Samples
were pressed and air dried in the field for a maximum period of three weeks and then transported to
a facility for oven-drying (80°C, 24h). Dry weight of aboveground biomass was calculated for each
morpho-species for each site.
Data analysis
Mean values with associated standard errors were calculated for each glade and forest site. Paired
t-tests were conducted to compare soil properties in the glades and adjacent forest sites. Spearman
rank correlation analyses were used to determine associations between altitude and soil and
vegetation variables.
Results
General attributes
The glades are variable in appearance, soil types, grazing regimes and history of land use (Fig. 2,
Table 1). The glades in the upper stratum tended to be irregular in shape and topography, whereas
those in the lower stratum tended to be bigger, flatter and more regular in shape. Grazing tended to
be seasonal at higher altitudes and permanent at the lower altitudes. Land use history was variable
within strata and across strata.
The three glades in the uppermost stratum had similar land use histories. Before the Derg
regime (approx. 30 y before present (hereafter, bp), the three glades were permanently inhabited
and permanently grazed. Kella was the site of a former imperial governmental village more than
70 y bp, but the village was gradually abandoned before the rise of the Derg. Shifa and Arrawa
supported smaller settlements. Only one of the three glades is currently used for settlement, and
this is seasonal use only. Currently all three glades are used seasonally for grazing. Oral histories
indicated that trees, shrubs and tall herbs have increased in abundance, the size of the glade has
decreased and bio-turbation has increased in importance over the past 30 y.
Figure 2. Three of the forest glades in the Harenna sampled in this study.
<strong>Walia</strong>-<strong>Special</strong> <strong>Edition</strong> on the Bale Mountains 134