Abstract:
Land use/cover (LULC) change has resulted from complex interactions of natural phenomena
and human activities. Population growth coupled with economic growth has increased the
demand of land resources for centuries and causing changes at various levels ranging from local
to global scales. Land use practice affects the distribution and supply of soil nutrients to plants
by altering soil properties. This study aimed at understanding the magnitude of LULC changes
and its drivers. It also attempts to examine the influence of LULC on soil properties in Rib
watershed. Satellite imageries of 1986, 1996, 2006, and 2016, field observation and four key
informant interviews were employed. In addition, soil samples were taken over natural forest,
grazing and cultivated lands in the two agroecological zones (Dega and High Dega) with five
replications. The samples were taken at two depths: 0-15cm (surface layer) and 15- 30cm
(subsurface layer) and mixed up to obtain composite and representative samples. Household
survey was also employed to obtain data on farmers’ perception of drivers of LULC changes.
Image analysis was accomplished on ERDAS Imagine and Arc GIS software to detect land
use/cover changes. Descriptive statistics, pair-wise ranking technique, Multivariate analysis of
variance (MANOVA), and Spearman’s rank correlation coefficient analyses in SPSS were
employed. The findings of this study revealed an expansion of cropland and settlement,
plantation, and bare land by 39.01, 24.88 and 5.62 ha/year, respectively between 1986 and 2016.
On the contrary, natural forest, grassland, and grazing land have decreased by 30, 26.6 and 12.9
ha/ year, respectively. Plantation shows increasing trends in Dega agroecological zone, whereas
in the High Dega cultivated/ farmlands & settlements, bare land has increased rapidly at the
expenses of other LULC. Significant differences (p<0.05) were also observed in OC, Ca2+, clay,
and silt fractions between the soils of natural forest, grazing land, and cultivated in the two
agroecologies. Soils of natural forest has higher OC, OC stock and TN. For instance, soils of
natural forest has higher OC stock (188.32 Mg/ha) as compared to soils of cultivated lands
(72.75 Mg/ha). BD of cultivated land was significantly higher than natural forest and grazing
lands. LULC changes were driven by increasing demands for new farmlands and increasing
demand for eucalyptus wood in rural and urban centres. Moreover, weakness in law enforcement
on natural resource conservation, low level of public participation in watershed management, and
low level of livelihood diversification were among the drivers of change. Therefore, the study
has suggested that the watershed ought to be enriched with of watershed restoration and natural
resource conservation activities.
