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Evaluating the impacts of land-use/land-cover (LULC) changes on ecosystem
service values (ESVs) is essential for sustainable use and management of
ecosystems. In this study, we evaluated the impact of LULC changes on ESVs
over the period 1982–2016/17 in contrasting, strongly human-impacted
agro-ecological environments: Guder (highland), Aba Gerima (midland), and
Debatie (lowland) watersheds of the Upper Blue Nile basin, Ethiopia.
During the study period, the continuous expansion of cultivated land at
the expense of natural vegetation (bushland, forest, and grazing land)
severely reduced the total ESV by about US$58 thousand (35%) in Aba Gerima
and US$31 thousand (29%) in Debatie watersheds. In contrast, the
unprecedented expansion of plantations, mainly through the planting of
Acacia decurrens, helped the total ESV rebound by about US$71 thousand
(54%) in Guder watershed after 2006, after it had decreased by about US$61
thousand (32%) between 1982 and 2006. The reduction in natural forest area
was the major contributor to the loss of total ESV in the study
watersheds, ranging from a reduction of US$31 thousand (63%) in Debatie to
US$96.9 thousand (70%) in Guder between 1982 and 2016/17. On an
area-specific basis, LULC changes reduced the average ESV from US$560 ha–1
yr–1 (1982) in Guder to US$306 ha–1 yr–1 (2017) in Debatie watersheds.
Specific ESVs such as provisioning (mainly as food production) and
regulating services (mainly as erosion control and climate regulation)
accounted for most of the total ESVs estimated for the study watersheds.
In most cases the total and specific ESVs of the watersheds were
negatively associated with the population growth, which in turn was
positively associated with the expansion of cultivated land over the study
period. In Guder watershed, however, ESVs were positively associated with
population growth, especially after 2012. This resulted primarily from the
conversion of cultivated land to plantations (predominantly with
nitrogen-fixing Acacia decurrens trees) because of the farmers’ growing
desire to rehabilitate degraded cultivated land while simultaneously
generating income through the sale of charcoal from this fast-growing
tree. Our results suggest, therefore, that future policy measures and
directions should focus on improving vegetation cover through planting
multipurpose trees such as Acacia decurrens to prevent future loss of ESV
in the midland and lowland regions of the Uppe...
114 views reported since publication in 2020.