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Land uses and soil and water conservation (SWC) structures affect topsoil moisture and carbon stocks, particularly in the water deficit semi-arid environment of the northern Ethiopian highlands. This study was undertaken to assess the effects of land use and SWC structures on topsoil moisture, biomass, and soil carbon. Soil moisture was measured manually using gravimetric methods and theta probes with data loggers. Vegetation was inventoried and soil samples collected to assess carbon stocks of biomass and soils of different land uses. Merebmiti catchment had higher average gravimetric soil moisture content (GSMC; 24%) in wetlands, with the lowest (13%) in exclosures, whereas Mayleba catchment had relatively higher GSMC (14%) in exclosures and the lowest (8%) in rangelands. In both catchments, GSMC was higher at sampling locations closer to SWC structures than farther away. Merebmiti had significantly more biomass carbon (28.9 Mg ha−1) than Mayleba (6.32 Mg C ha−1). Higher soil organic carbon stocks were found in exclosures (46.1 ± 2.20 Mg ha−1) and wetlands (62.1 ± 2.9 Mg ha−1) than in frequently cultivated croplands (24.3 ± 1.4 Mg ha−1). Effective management of land use and implementation of SWC structures remarkably improves topsoil moisture content and carbon stocks in these catchments. [ABSTRACT FROM AUTHOR]

Exclosures are established with the objective of rehabilitating degraded lands and restoring of woody vegetation. Various studies have been conducted to evaluate the success of exclosure on restoring woody species diversity. However, works focusing on the effect of topographic factors on woody species diversity are scarce. Understanding the factors that determine woody species diversity is important for management purposes. Therefore, this paper analyzes the effect of altitude, slope, and aspect as topographic variables on woody species diversity in Dawsura exclosure in northern Ethiopia. Data on species identity, abundance, slope, elevation and aspect were recorded from 58 sampling plots. Different diversity indices were used to analyze the data and one-way ANOVA and linear regression was conducted. There were a total of 34 woody species represented 15 families, of which 62% and 38% were trees and shrubs respectively. Altitude (r 2 = 0.63, p = 0.000 and r = 0.794, p < 0.01) and slope (r 2 = 0.57, p = 0.002 and r = 0.68, p < 0.01) correlated significantly and positively with Shannon diversity, whereas aspect (r 2 = 0.12, p = 0.378 and r = 0.27, p > 0.05) did not correlate significantly with Shannon diversity. Woody species diversity at moderate (1.44) and high (1.85) altitudes was significantly different from that of low (0.86) altitude areas (p = 0.0013). Furthermore, significantly higher woody species diversity was recorded at steep slope (1.88) and moderately steep slope (1.62) areas as compared to the gentle slope (0.95) areas. No significant variation was observed in woody species diversity among the aspect categories (p > 0.05). The study concludes that woody species diversity is largely regulated by slope and altitude than aspect in the exclosure. We suggest other environmental and anthropogenic variables should be taken into consideration in future studies on woody species diversity., (© 2019 The Author(s).)