Restoration of degraded drylands through exclosures enhancing woody species diversity and soil nutrients in the highlands of Tigray, Northern Ethiopia

Abstract

Exclusion of grazing animals and tree plantations were among the methods used for the rehabilitation of degraded lands in tropical semiarid areas. Exclosures can foster secondary forest succession by improving soil conditions, attracting seed-dispersal agents and modifying microclimate for understory growth. This paper compares the woody species diversity and soil chemical properties under exclosure with increasing age and grazing land at different slope positions. The study has been conducted in northern Ethiopia from 12 exclosure sites paired each with adjacent grazing land with four treatments replicated three times. In the entire study 216 plots were examined of which 108 were in exclosures and 108 in communal grazing lands.There were four age classes and three slope positions in each of the landuses. Vegetation data were collected using plots measuring 100 m 2 . Soils for physicochemical properties were collected from the four corners and center of 5 × 5m plots which was inside the 10 × 10m plot. A total of 61 woody plant species belonging to 41 families were recorded. Diversity and species richness were higher in the exclosures than in grazing lands. Among exclosures these parameters were higher in exclosures older than 30 years and at the foot of the slope. Grazing lands, the youngest exclosures and upper elevation gradient recorded lower values. Chemical soil properties were significantly higher in the exclosures, among them in the oldest exclosures and at foot elevation (except for P) than these were in the grazing land, the youngest exclosures and upper parts of slopes respectively. Exclosures are instrumental to improve the woody species diversity and soil chemical properties in the drylands.

Diversity of Woody Species and Biomass Carbon Stock in Response to Exclosure Age in Central Dry Lowlands of Ethiopia

“…Only three family names, i.e., Boraginaceae, Fabaceae, and Tiliaceae were observed in the open grazing land (Tables 4-7). As in many other places of Ethiopia, the Fabaceae family contributed the greatest number of species in the study area (Mekuria and Yami, 2013;Mekuria et al, 2015;Gebremedihin et al, 2018). Despite its consistency, both family numbers and species numbers increase with an increase in age of exclosure.…”

Ecosystem Service Values Changes in Response to Land-Use/Land-Cover Dynamics in Dry Afromontane Forest in Northern Ethiopia

“…Trends observed in the first period (1985–2000) could be explained by the improvement of dense forest and open forest as a result of the introduction of different interventions (e.g., intensive soil and water conservation, exclosure establishment, and community participation) [47,48,49]. The impacts of these interventions could have translated into the improvements observed between 1985 and 2000.…”

A global systematic review on orchid data in Protected Areas

“…Protected Areas are a key component of the global response to environmental changes and degradation (Gaston et al, 2008;Conroy et al, 2011). They positively contribute to biodiversity conservation (Leverington et al, 2010;Akasaka et al, 2017;Ruchin & Makarkin, 2017;Gebremedihin et al, 2018). The effectiveness of Protected Area Networks in different regions depends on representativeness of endemic and threatened taxa (Jackson et al, 2009;Vellak et al, 2009;Gray et al, 2016), size (Schödelbauerová et al, 2009;Leroux et al, 2015), type (Lemenager et al, 2014;Fitzsimons, 2015;Furlonge et al, 2015), and protection support on behalf of government and non-government authorities Leverington et al, 2010;Tuvi et al, 2011;Bicknell et al, 2017).…”