Tree-based ecosystem services supply and multifunctionality of church forests and their agricultural matrix near Lake Tana,Ethiopia

Ecosystem services(ES)are the connection between nature and society,and are essential for the well-being of local communities that depend on them.In Ethiopia,church forests and the surrounding agricultural matrix supply numerous ES.However,the ES delivered by both land use types have not yet been assessed simultaneously.Here we surveyed both church forests and their agricultural matrices,aiming to quantify,compare and unravel the drivers underlying tree-based ES supply,density and multifunctionality.We found that almost all church forests and half of the agricultural matrices provided high ES densities.ES multifunctionality was higher in the agricultural matrices,suggesting that people deliberately conserve or plant multifunctional tree species.Furthermore,the supply of all categories of ES was positively correlated with church forest age(p-value<0.001)in the agricultural matrix,while the extent of church forest was positively correlated with the density of all categories ecosystem services score in the church forests(p-value<0.001).Our results can be used to prioritize conservation efforts at sites that provide high levels of ES supply,ES density and ES multifunctionality,and to prioritize restoration efforts at sites with low levels thereof.

Changes in land use/cover mapped over 80 years in the Highlands of Northern Ethiopia

Despite many studies on land degradation in the Highlands of Northern Ethiopia, quantitative information regarding long-term changes in land use/cover(LUC) is rare. Hence, this study aims to investigate the LUC changes in the Geba catchment(5142 km2), Northern Ethiopia, over 80 years(1935–2014). Aerial photographs(APs) of the 1930 s and Google Earth(GE) images(2014) were used. The point-count technique was utilized by overlaying a grid on APs and GE images. The occurrence of cropland, forest, grassland, shrubland, bare land, built-up areas and water body was counted to compute their fractions. A multivariate adaptive regression spline was applied to identify the explanatory factors of LUC and to create fractional maps of LUC. The results indicate significant changes of most types, except for forest and cropland. In the 1930 s, shrubland(48%) was dominant, followed by cropland(39%). The fraction of cropland in 2014(42%) remained approximately the same as in the 1930 s, while shrubland significantly dropped to 37%. Forests shrank further from a meagre 6.3% in the 1930 s to 2.3% in 2014. High overall accuracies(93% and 83%) and strong Kappa coefficients(89% and 72%) for point counts and fractional maps respectively indicate the validity of the techniques used for LUC mapping.

Transferring Google Earth observations to GIS-software: example from gully erosion study

High-resolution images availableonGoogle Earth are increasingly beingconsulted in geographic studies.However,most studies limit themselves to visualizations or on-screen measurements.Google Earth allows users to create points,lines,and polygons on-screen,which can be saved as Keyhole Markup Language(KML)files.Here,the use of R statistics freeware is proposed to easilyconvertthese files to the shapefile format[or‘.shp file format’],which can be loaded into Geographic Information System(GIS)software(ESRI ArcGIS 9 in our example).The geospatial data integration in GIS strongly increases the analysis possibilities.

Using image-based modelling(SfM–MVS)to produce a 1935 ortho-mosaic of the Ethiopian highlands

Approximately 34,000 aerial photographs covering large parts of Ethiopia and dating back to 1935–1941 have been recently recovered.These allow investigating environmental dynamics for a past period that until now is only accessible from terrestrial photographs or narratives.As the archive consists of both oblique and vertical aerial photographs that cover rather small areas,methods of image-based modelling were used to orthorectify the images.In this study,9 vertical and 18 low oblique aerial photographs were processed as an ortho-mosaic,covering an area of 25 km2,west of Wukro town in northern Ethiopia.Using 15 control points(derived from Google Earth),a Root Means Square Error of 28.5 m in X 35.4 m in Y were achieved.These values can be viewed as optimal,given the relatively low resolution and poor quality of the imagery,the lack of metadata,the geometric quality of the Google Earth imagery and the recording characteristics.Land use remained largely similar since 1936,with large parts of the land being used as cropland or extensive grazing areas.Most remarkable changes are the strong expansion of the settlements as well as land management improvements.In a larger effort,ortho-mosaics covering large parts of Ethiopia in 1935–1941 will be produced.