Abstract:
Land degradation is revealed in the form of vegetation and soil fertility degradation. It is
becoming a major ecological and agricultural problem in Ethiopia. To overcome the
problems of land degradation area exclosure is used as strategy to restore degraded lands in
Hulbarag Wereda, Siltie Zone, SNNPRS. The general objective is to assess and evaluate the
usefulness of exclosure technique in enhancing rehabilitation of degraded ecosystem and
thereby increase the natural capital in the area. Woody plant species and soil samples were
collected with the transects from area exclosure for eight year and adjacent degraded land
with similar landscape positions. Both soil and woody plant species were collected from
transects by systematic sampling plot design technique. The woody plant species were
identified by using a field guideline. The woody species diversity was determined by Shannon
diversity. To determine soil fertility status of area exclosure and adjacent degraded soil,
samples were analyzed for soil organic carbon (SOC), cation exchange capacity (CEC), total
nitrogen (TN), pH, electrical conductivity (EC), available phosphorus (Av. P), exchangeable
bases (K+
, Na+
, Ca+
, Mg2+), soil texture, moisture content and bulk density (BD).
Comparative assessment result of woody plant species analysis showed that the density of
woody species in the exclosure and degraded site were 778 and 222 individuals per hectare,
respectively. A total of 16 woody species, representing 12 families were recorded in the study
site. Out of the 12 families, all were recorded in the exclosure while 5 were recorded in the
degraded site. Out of the 16 species, 15 were recorded in the exclosure while six were in the
degraded site. A total of 10 species were recorded in the exclosure, which were absent in the
degraded site. Similarly a species was recorded in the degraded sites, which were not present
in the exclosure. Exclosed areas had significantly (P<0.05) different values for all soil
parameters except for bulk density, EC and pH. The higher bulk density, sand, EC, and pH
were recorded in the degraded site, whereas the rest of soil properties were high in exclosure.
The present study indicated that, the mean values for degraded and exclosure sites in soil of
OC, TN and Av.P were 2.21 and 1.61, 0.19 and 0.14, and 7.92 and 5.88, respectivily. Apart
from increasing woody plant species and soil fertility improvement, these local communities
has benefited from the exclosure by collecting of forage for livestock via cut-and-carry system
and farmland protection from clotting with silt and mud from the upper catchments. This has
enabled this local community to develop a positive attitude towards exclosure development.
Generally, area exclosure has a great contribution to restore woody plant species and soil
fertility status in the study area. Therefore, to improve the livelihood of the local community
area exclosure practices should be expanded to other degraded watersheds and private
farmlands.
