Variation in Ecosystem Service Values in an Agroforestry Dominated Landscape in Ethiopia: Implications for Land Use and Conservation Policy

Abstract

Human pressure on a rugged and fragile landscape can cause land use/cover changes that significantly alter the provision of ecosystem services. Estimating the multiple services, particularly those obtained from agroforestry systems, is seldom attempted. A combined approach of geospatial technology, cross-sectional field investigations, and economic valuation of natural capital was used to develop an ecosystem service valuation (ESV) model to estimate changes in ESV between 1986 and 2015 in southern Ethiopia. Over 120 values were sourced, mainly from an ecosystem service valuation database and allied sources, to establish value coefficients via benefit transfer method. Our 1848 km 2 study landscape, with eight land use categories, yielded an annual total ESV of $129 × 10 6 in 1986 and $147 × 10 6 in 2015, a 14.2% ($18.3 million) increase in three decades, showing its relative resilience. Yet we observed losses of natural vegetation classes whose area and/or value coefficients were too small to offset their increased value from expanding agroforestry and wetland/marshes, which have the largest cover share and highest economic value, respectively. Appreciating the unique features of agroforests, we strongly recommend that their economic value is studied as a separate ecosystem for further valuation accuracy improvement.

Impact of Land Use/Cover Change on Ecosystem Service Values in the Kilombero Valley Floodplain, Southeastern Tanzania

“…Furthermore, an accuracy assessment was performed and indicated good overall classification results, with an accuracy of 86.7% and a kappa coefficient of 0.82, which satisfied the requirements of accuracy test and validated the classification results [29]. The eight LULC types were then compared with their corresponding equivalent biome, which were developed Costanza et al [1], Kindu et al [7] and Temesgen et al [33]. The most representative biome was used as a proxy for each LULC type, including (1) cropland for agriculture; (2) desert for bare land; (3) tropical forest for bushland; (4) tropical forest for forest; (5) grass/rangelands for grassland; (6) urban area for settlement; (7) rivers/lakes for water and (8) wetland/marsh for wetland (see Table 1).…”

“…Table 1. Land use and land cover (LULC) types with their areas in increment of 10 2 ha for 1990, 2010 and 2016 adapted from Msofe et al [29] and biome equivalents with their corresponding ecosystem service value coefficients (VC) in 1994 US$ ha −1 year −1 (a) modified local value coefficients (adapted from Kindu et al and Temesgen et al [7,33]), with permission from Elsevier, 2016 and MDPI, 2018, respectively (b) global value coefficients (adapted from Costanza et al [1], with permission from Nature research, 1997). Furthermore, an accuracy assessment was performed and indicated good overall classification results, with an accuracy of 86.7% and a kappa coefficient of 0.82, which satisfied the requirements of accuracy test and validated the classification results [29].…”

“…It was designated as a Ramsar site in 2002 and therefore managed by the Ministry of Natural Resources and Tourism through stipulated rules and regulations following the Ramsar convention [34]. (1) To estimate changes in ecosystem service values in response to land use/cover change that occurred over the past 26 years (1990-2016) in Kilombero Valley floodplain based on the adopted global and modified local value coefficients (1994 US$ ha -1 year -1 ) [1,7,33]. (2) To explore the changes of individual ecosystem function values due to the effects of dynamics in each land use and land cover type.…”

“…This study employed the benefit transfer approach to estimate the ecosystem service values based on the adopted global and modified local value coefficients of the ecosystem services for the target LULC types; for examples, see [6,11,37]. The adopted modified local value coefficients of the ecosystem services for cropland, desert, tropical forest, grasslands, urban and freshwater biomes were obtained from Kindu et al [7], whereas the value coefficients for wetland/marsh biome were obtained from Temesgen et al [33]. These coefficients were generated based on expert knowledge of the ecological conditions of the Ethiopian highlands landscape and from other literature, mainly from the TEEB valuation database [10].…”

“…Moreover, the change in the ESVs was determined by calculating the differences between the estimated values for each LULC category in The LULC datasets for each year, which were used as proxies for the measurement of the ESVs were prepared, and the corresponding area in hectares was assessed and presented in a raster in the GIS. In the ecosystem service valuation process, the value coefficients are assigned to each LULC type, according to this study value coefficients used were those of Costanza et al [1] and the adopted local modified ecosystem services coefficients followed those of Kindu et al and Temesgen et al [7,33] (see Table 1). Then, the total value of ecosystem services in the study area for 1990, 2010 and 2016 was calculated by multiplying the area of a given LULC type by the corresponding modified ecosystem service value coefficients that were extracted from weight factors of the ecosystem services per hectare of each biome, see equation (1), which was used by [7,11], as follows:…”