Vegetative and reproductive biomass allocation responses of herbaceous plant species to induced drought in a semi–arid highland savanna, central, Namibia

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

Grantor dc:publisher

University of Namibia

Year dc:date.issued

2024

Author dc:creator

• Nashini, Martha E.

Advisor dc:contributor.advisor

• Kwembeya, Ezekiel

• Climate change
• Drought
• Rainout shelters
• Herbaceous plants
• Namibia
• University of Namibia

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/11070/4272

OAI identifier oai:identifier

oai:repository.unam.edu.na:11070/4272