Influence of Grazing Intensity on Soil Properties and Shaping Herbaceous Plant Communities in Semi-Arid Dambo Wetlands of Zimbabwe

Abstract

Key issues of concern regarding the environmental impacts of livestock on grazing land are their effects on soil, water quality, and biodiversity. This study was carried out to determine how grazing intensity influences soil physical and chemical properties and occurrence of herbaceous plant species in dambo wetlands. Three categories of grazing intensity were selected from communal, small scale commercial and large scale commercial land. Dambos from the large scale commercial land functioned as the control. Data analysis included ANOVA and multivariate tests from CANOCO. There were significantly negative changes to soil nutrient status in communal dambos though with a higher number of rare taxa. Sodium, phosphorous, pH and infiltration rate were significant determinants of plant species occurrence. Overgrazing is threatening the productivity, stability, and ecological functioning of dambo soils in communal Zimbabwe. These dambos also require special conservation and management priorities as they contain a large number of rare plant species.

Institutional arrangements governing wetland utilization and conservation in communal areas of Zimbabwe

“…Nevertheless, cattle trampling is reported by 9.8% household heads and 26.7% teenagers to be responsible for desiccation in unprotected wetland sections. The effect of cattle trampling on wetlands was also well studied (Sibanda, 2005;Dahwa et al, 2013;Morris and Reich, 2013).…”

Influence of Grazing Intensity on Swamp Plant Communities in the Tropical Montane Wetland Ecosystems, Nilgiris, Southern India

“…Several studies have demonstrated that grazing intensity is one of the main drivers of wetland ecosystem dynamics (Marty, 2005; Jones et al, 2011; Dahwa et al, 2013). For instance, high grazing intensity is strongly correlated with high plant mortality and low recruitment rates, leading to changes in community structure and loss of species diversity (Milchunas et al, 1988;Gordon et al, 2004;Mysterud, 2006).…”

“…However, excessive grazing can result in the ecological disturbance of vulnerable grassland and wetland ecosystems leading to biodiversity loss and biological invasions (Milchunas and Lauenroth, 1993;Perevolotsky and Seligman, 1998;Marty, 2005;Dahwa et al, 2013). Thus the response of local and regional biodiversity to grazing may be positive or negative depending upon its intensity and frequency and the species specific responses of the constituent vegetative and herbivore taxa (Freilich et al, 2003;Maestas et al, 2003).…”

“…Grazing by large herbivores plays a key role in maintaining the diversity, structure and function of many terrestrial ecosystems (Dahwa et al, 2013;Howland et al, 2014;Freitas et al, 2014;Ingerpuu and Sarv, 2015). However, excessive grazing can result in the ecological disturbance of vulnerable grassland and wetland ecosystems leading to biodiversity loss and biological invasions (Milchunas and Lauenroth, 1993;Perevolotsky and Seligman, 1998;Marty, 2005;Dahwa et al, 2013).…”

Effect of temporal variation in precipitation on the demography of four herbaceous populations in a tropical dry forest area in Northeastern Brazil

“…For example, variations in the availability of nutrients and water content in the soil on a small scale, form microhabitats that harbor herbaceous populations more numerous (Haskell, Flaspohler, Webster, & Meyer, 2010;Dahwa et al, 2013). Although we have not quantified the soil properties in this study, it is possible that they can mitigate the effect of temporal variation in precipitation and contribute to the maintenance of some herbaceous populations of the caatinga.…”