2026-09-23T12:17:58Zhttps://repository.unam.edu.na/server/oai/request

oai:repository.unam.edu.na:11070/42722026-06-27T22:01:08Zcom_11070_3406com_11070_3311com_11070_3304col_11070_87

Kwembeya, Ezekiel Nashini, Martha E. 2026-06-24T11:11:17Z 2026-06-24T11:11:17Z 2024 http://hdl.handle.net/11070/4272 A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Biodiversity Management Namibia's arid conditions renders its vegetation vulnerable to changes in precipitation, affecting plant growth and biomass allocation. Recurring droughts, intensified by climate change lead to alterations in biomass allocation. Thus resulting in the reduction of medicinal products, livestock fodder, and food sources while disrupting nutrient cycles. This study investigated herbaceous drought responses in biomass allocation and the influence of environmental variables on these patterns, aiming to inform ecosystem management to conserve Namibia's biodiversity. Twenty fixed rainout shelters (4 m x 4 m) were used at Neudamm Agricultural Farm to simulate drought conditions with four treatments (0%, 20%, 40%, and 80% rainfall reduction), each replicated five times. Environmental parameters, including temperature (measured with a mercury thermometer), soil moisture content and chlorophyll content (using a SPAD-502 Plus Chlorophyll meter) were recorded before biomass harvesting. Biomass was collected from 0.5 m x 0.5 m quadrants, with aboveground biomass clipped at ground level and belowground biomass obtained through soil excavation. The Generalized Linear Models indicate that drought treatments are significant predictors of reproductive biomass allocation (χ²(3) = 13.114, p < 0.004), while temperature significantly influences vegetative biomass allocation (χ²(1) = 17.103, p < 0.004). The Friedman test results show a significant difference in chlorophyll content across drought treatments (χ² = 18.456, df = 1, p < 0.001), with Aptosimum lineare and Ocimum americanum exhibiting the highest chlorophyll levels under treatment 60 highlighting the resilience of these species in arid savannas. These findings underscore the significant impact of drought on biomass allocation and the need for targeted interventions to mitigate its effects on plant growth and development en University of Namibia Climate change Drought Rainout shelters Herbaceous plants Namibia University of Namibia Vegetative and reproductive biomass allocation responses of herbaceous plant species to induced drought in a semi–arid highland savanna, central, Namibia Thesisopen.access