Catching a Fever: A Comparison of Vachellia xanthophloea Populations in the Limpopo and Luvuvhu River Floodplains of the Makuleke Contractual Park

Authors

Kianie B. David, University of Nebraska-LincolnFollow

First Advisor

Lord Ameyaw

Committee Members

John Carroll, Sabrina Russo

Date of this Version

7-2025

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Natural Resource Sciences

Under the supervision of Professor Lord Ameyaw

Lincoln, Nebraska, July 2025

Comments

Copyright 2025, Kianie B. David. Used by permission

Abstract

This study investigates patterns of stand structure regeneration, growth characteristics, and coarse woody debris (CWD) patterns in Vachellia xanthophloea (fever tree) stands within the Makuleke Contractual Park (MCP), a semi-arid savanna system in northern Kruger National Park (KNP), South Africa. Fieldwork was conducted across two stand types: a monospecific fever tree stand in Rietbok Vlei and a mixed-species stand in the Western Nhlangaluwe Floodplain where fever tree is established with Faidherbia albida (ana tree). Data were collected from 20 total 1/4-acre (1,011 m²) circular plots between both stands in 2024 and 2025, including seedling root collar diameter (RCD), mature tree diameter at breast height (DBH) and height, damage class, CWD accumulation and decay class, volumetric water content (VWC), canopy cover, elevation, and understory composition. The mixed-species stand supported higher seedling abundance in 2024 and 2025, along with greater mean RCD. This stand also exhibited higher soil moisture, more consistent canopy cover, and greater understory species richness, indicating more favorable microsite conditions for regeneration. Mature fever trees in the mixed-species stand exhibited a greater DBH, while height did not differ meaningfully between stands. The monospecific stand had a greater variation in elevation and contained more CWD overall, showing higher frequencies of advanced decay classes and suggesting elevated mortality and possible even-aged senescence. Damage observations revealed greater disturbance in the monospecific stand, particularly from elephants, insects, and ungulates. A pulse event in January 2025 rainfall spurred a 57.4% increase in seedling abundance at Rietbok Vlei in 2025. This suggests that recruitment and succession is disturbance-driven in the monospecific stand. These data reflect differences in regeneration, growth, and stand senescence decline between stand types and provide insight into the biotic and abiotic factors shaping fever tree populations in the MCP. Observed patterns align with existing models of episodic recruitment, patch dynamics, and species bottlenecks, and may support future long-term forest health monitoring in the MCP.

Advisor: Dr. Lord Ameyaw