Exclosures restored the density and root colonization of arbuscular mycorrhizal fungi in Tigray, Northern Ethiopia

Abstract

Introduction: Exclusion of grazing animals and tree plantations were among the methods used for the restoration of degraded lands in tropical semiarid areas. Exclosures can foster secondary forest succession by improving soil conditions and modifying microclimate for understory growth. This paper compared the arbuscular mycorrhizal fungi (AMF) spore density, root colonization of woody plants and soil chemical properties under exclosure with increasing age, and grazing land at different slope positions. Methods: The study was conducted in northern Ethiopia from 12 exclosure sites paired each with adjacent grazing land in total from 24 sites 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 land uses. Composite soil and root samples were collected using nested plots measuring 100m 2 from four sides of 1763 plants for spore enumeration and root colonization. Soils for chemical properties were collected from the four corners and center of 5 m × 5 m plots. Results: All the 61 woody plant species that belong to 41 families were colonized by AMF. Spore density and root colonization were significantly higher in exclosures as compared to grazing land and increased with increasing ages of exclosures. Foot slope had significantly higher spore density and root colonization than middle and upper slopes. Soil chemical properties were significantly higher in the exclosure, oldest age of exclosure, and foot slope position (except P). AMF spore density and root colonization were significantly positively correlated with soil chemical properties.

Effect of community-based soil and water conservation practices on arbuscular mycorrhizal fungi types, spore densities, root colonization, and soil nutrients in the northern highlands of Ethiopia

“…The variation could be due to displacement of spores by erosion from the upper to down slope position. This is in agreement to Birhane et al [23] who found significantly higher spore density at the foot than the middle and upper slope positions. Large variations in spore density between slope positions could also be due to the properties of the soils, host relations, and the differential survival strategies of AMF [22].…”

“…It was also reported that livestock and human disturbances decreased AMF spore density, root colonization, and nutrient availability [22]. However, establishment of exclosures on degraded communal grazing lands significantly improved spore density and root colonization [23]. Nutrient stocks and concentrations of soil organic matter (SOM), total nitrogen (TN), and available phosphorus (AP) were found higher in areas with high AMF [21].…”

Effects of Forest Composition and Disturbance on Arbuscular Mycorrhizae Spore Density, Arbuscular Mycorrhizae Root Colonization and Soil Carbon Stocks in a Dry Afromontane Forest in Northern Ethiopia

“…Spore density was positively and significantly correlated with root colonization, as has been reported by others [48,[69][70][71]. However, some researchers indicated no correlation between spore density and root colonization [15,49].…”

“…Zhao et al [47] found that spore density ranged from 50 to 1908 in 100 g −1 dry soil across three forest types (i.e., primary, secondary and limestone forest) in the tropical ecoregions of SW China. Similarly, Birhane et al [4] found up to 69 spores 100 g −1 dry soil in dry deciduous wood lands, while Birhane et al [48] reported up to 2980 spores per 100 g of dry soil in a dry Afromontane forest. Moreover, Dobo et al [49] found spore densities ranging from 6 to 1010 from different plant species in three land-use types in southern Ethiopia.…”

How Diverse is Tree Planting in the Central Plateau of Burkina Faso? Comparing Small-Scale Restoration with Other Planting Initiatives

“…The ecological implications deriving from the implementation of fences have been described in a number of case studies from different regions of the world. The benefits consist in enhanced regeneration of natural vegetation, reduction of runoff and erosion, land stabilization, increase in water availability and improvement in soil physical and chemical properties [43][44][45][46][47][48]. Prolonged exclusion of livestock grazing produces over time a significant increase in aboveground and belowground biomass and species richness [49,50].…”