Effects of Droughts on Vegetation Condition and Ecosystem Service Delivery in Data-Poor Areas: A Case of Bobirwa Sub-District, Limpopo Basin and Botswana

Abstract

Understanding the effects of droughts on vegetation and ecosystem services (ES) is important for climate change adaptation. However, drought occurrence varies across space and time. We examined drought dynamics and impacts on vegetation and ES in the semi-arid Limpopo Basin of Botswana. Weather station precipitation, remotely sensed normalized difference vegetation index (NDVI) and participatory mapping exercises provided data for the analyses. Results show that between 1980 and 2015, rainfall anomaly indices of potential drought years ranged between −4.38 and −0.12. The longest spell of below-average rainfall occurred between 1992 and 1996. On average, drought events lasted for 1.9 years and recurred every 2.3 years. Although the overall drought frequency was 3.7 times in every 5 years, drought prevalence increased to 50%, 60% and 70% between 1981–1990, 1991–2000, and 2001–2010, respectively. The wet season average vegetation condition index between 2000 and 2015 revealed the occurrence of severe-to-extreme droughts in 2002–2003, 2005, 2008–2009 and 2012–2013 and light-to-moderate droughts in 2004, 2006–2007 and 2011, giving a drought prevalence of 73.3%. The increased frequency and severity of droughts is diminishing natural vegetation, crop productivity and several provisioning ES through moisture stress and drought-induced agricultural expansions. There exists an urgent need for smallholder irrigation development in Bobirwa sub-district to improve crop productivity and reduce the drought-induced conversion of woodlands to agriculture.

Drought Disaster Risk Adaptation through Ecosystem Services-Based Solutions: Way Forward for South Africa

“…Using selected parameters, the analysis identified a few types of approaches that improve ecosystem functionality and provide significant environmental and socioeconomic benefits, thereby helping to adjust to drought effects. However, out of 12 researches on drought and ecosystem services-related studies, only one study was done on Limpopo Basin and Botswana, which basically focused on the effects of droughts on vegetation and ecosystem services and its relevance to climate change adaptation including drought events [16]. In order to successfully incorporate these approaches into ecosystem services-based adaptation programs and complement them with more conventional drought disaster risk mitigation and management strategies, more information on these approaches is required.…”

“…In total, 12 papers were acquired; after reading through their titles and abstracts, however, it was noted that all of them dealt with topics beyond the scope of this review. For instance, a study focused on the effects of droughts on vegetation conditions and ecosystem service [16]. Another study dealt with the short-term effects of crop diversity on resilience and ecosystem service provision under drought [17].…”

Vegetation Trends, Drought Severity and Land Use-Land Cover Change during the Growing Season in Semi-Arid Contexts

“…For example, when compared to the mean, vegetation productivity was very limited in 2002-2003 (the worst drought episode in the time series). Drought occurrence was evident during the growing seasons of eight declared drought years in line with [21,30]. FAO special alert for Southern Africa in 2015 noted the retarded growth of early-planted crops as soil moisture was very low at the beginning of the growing season in most parts of the southern African region, including Botswana [44].…”

“…This bareland condition due to drought-induced vegetation decline is further exacerbated by human activities, such as overgrazing. In some instances, such as in Bobonong, researchers [30] found increases in bareland patches in communal grazing areas. Despite declining vegetation conditions during a four-year prolonged drought (2002)(2003)(2004)(2005), livestock overgrazed and natural pastures degraded, as pastoralists had no incentive to destock or sell their cattle because of the slump in prices due to the prevalence of Foot-and-Mouth cattle disease during the drought.…”

“…With the increasing availability of free satellite image datasets of good temporal and spatial resolution, RS affords rapid and cost-effective assessment and monitoring of droughts. Drought effects on vegetation and ecosystem services were examined in the Bobirwa sub-district, Botswana using RS-based indices [30]. Although the drought situation is increasingly assessed in Botswana, the use of RS in examining droughts in Botswana is still very limited.…”