Community assembly of adult odonates in lacustrine systems of an understudied world heritage site of south-eastern Zimbabwe

Odonata (dragonflies and damselflies) are efficacious for management and conservation efforts in freshwaters. In recent times, increased effort has gone into enhancing awareness, data and information on dragonflies among scientists and policymakers. Here, we examined the Odonata community of dams within the Matobo National Park, a world heritage site in southern Zimbabwe. Specifically, we determined diversity of larval and adult odonate in five dams over one year. Several physico-chemical parameters were measured, including pH, total dissolved salts (TDS), electrical conductivity (EC). Further, we assessed how habitat types (i.e., detritus, sand, gravel, plant type) affect Odonata communities. In addition, surveys were conducted to identify critical threats to Odonata in the Matobo National Park and surrounding areas. Broadly, results showed that Odonata nymphs and volant adults did not change predictably across all sampling occasions. Further, pH was positively correlated with Libellulidae and Platycnemididae, whereas TDS and EC were positively correlated with Libellulidae, Platycnemididae and Macromiidae. Contrariwise, Gomphidae were found to be negatively correlated to TDS, EC and pH. The threat analyses identified natural system modifications, agricultural expansion and intensification, as well as human intrusions and disturbance as the major threats to Odonata and freshwater resources in Matobo National Park. Taken together, these data provide baseline data that will be useful for future monitoring of threats and subsequently conservation strategies in the Matobo National Park and other protected areas in Southern Africa.https://worlddragonfly.org/ijoam2022Geography, Geoinformatics and Meteorolog

Impact of agricultural intensification on biodiversity and secondary succession in the Mid-Zambezi Valley, Northern Zimbabwe

In this thesis, the impact of woodland clearing, cultivation intensity and fallowing on tree species diversity, physiognomy and dominance was tested in the semi-arid mid-Zambezi valley, northern Zimbabwe. This study further tested the impact of agriculture on arthropod biodiversity using butterflies in the genus Charaxes (Lepidoptera: Nymphalidae) and beetles in the subfamily Cetoniinae (Coleoptera: Scarabaeidae). This study also investigated vegetation dynamics within recovering fallow areas. Results showed that, in both intensified and less intensified agricultural areas, conversion of natural woodland areas to cropped fields result in rapid decrease in tree diversity at field level, while at landscape level agricultural activities do not affect woody species diversity, at least in the short term. Instead, through selective cutting down of trees and subsequent crop cultivation negative impacts of woodland conversion is on tree physiognomy and dominance. At a higher trophic level, results showed that woodland clearing resulted in a decrease in abundance and loss of diversity of fruit-feeding butterflies of the genus Charaxes and beetles of the subfamily Cetoniinae with loss recorded in areas homogeneous intensively cultivated areas. Furthermore, results showed that, vegetation dynamics within fallow areas area characterised by a change in floristic composition with high rates of above-ground biomass accumulation driven by dominance of invasive species such as Acacia tortilis subsp spirocarpa. All sets of results in this study indicated that any efforts to conserve biodiversity within agricultural landscapes in the mid-Zambezi valley may have to focus on implementing an agricultural paradigm that maintains a mosaic of different land-use units, each in a different phase of clearance-cultivation-abandonment-recovery-clearance cycle.,Research Platform-Production and Conservation in Partnership,(RP-PCP)grant; DAAD; University of Zimbabwe Tropical Resource Ecology Programme(TREP

A test of the Lake Habitat Survey method in Cleveland Reservoir and Lake Chivero (Manyame River Basin, Zimbabwe)

The Lake Habitat Survey (LHS) method has only been applied once in a tropical African reservoir and could potentially be a useful tool for hydromorphological impact assessments. This study (October 2012) tested the application of the LHS method to two Zimbabwean reservoirs, Cleveland and Chivero, which are impacted differently by human activities within their catchments with varying levels of physical impacts and lakeshore use. The Lake Habitat Quality Assessment (LHQA) and Lake Habitat Modification Score (LHMS) were used to assess the habitat quality and the magnitude of human impact on the reservoirs. Cleveland Reservoir LHQA (78 out of 112) and LHMS (16 out of 42) scores are indicative of relatively low human pressure (e.g. angling and canoeing). Results show that although Cleveland Reservoir is coming under increasing anthropogenic pressure, it does not appear to suffer from major alien plant invasion as compared to Lake Chivero, which scored 62/112 and 32/42 for the LHQA and LHMS, respectively. There were no significant differences between the numbers of vegetation layers in the riparian vegetation of the two reservoirs. However, there were significant differences in the number of macrophyte species and shoreline/riparian pressures between the two reservoirs. In conclusion, the use of the LHS can better enhance quality and reliability of lake hydromorphological assessments in tropical systems, where such an investigation is required to support decision making, after adaptations of the method have been made, i.e., inclusion of catchment impacts on lakes and reservoirs in LHS scoring metrics.Keywords: Lake Habitat Modification Score, Lake Habitat Quality Assessment, human pressure, hydromorphology, catchmen

Farming does not necessarily conflict with tree diversity in the mid-Zambezi valley, Zimbabwe

We tested whether cultivation and fallowing have any significant effect on tree species diversity and dominance in semi-arid Zimbabwe. To this end, we quantified tree species diversity and physiognomy on two soil types (mutapo and bandati) stratified into three land-use categories, i.e., cultivated land, fallow land and woodland. Results showed that tree species diversity was significantly different on the two soil types. Tree species diversity was high on bandati soil and low on mutapo soil. Results also showed that there was significant difference in tree species diversity among the three land-use categories on mutapo soil but no differences on bandati soil. Pairwise comparisons revealed significant differences in species diversity between paired categories on mutapo soil but no significant differences on bandati soil. Tree physiognomy was significantly different among all three land use categories. Colophospermum mopane and Diospyros kirkii were the dominant species within woodlands, while Acacia tortilis subsp. spirocarpa replaced them as the dominant species within the fallow land category. These results indicate that woodland conversion for cultivation purposes has no immediate significant effect on tree species diversity on bandati soil, while it has a pronounced effect on mutapo soil, at least in the short term. (Résumé d'auteur