Short-Term Influence of Burning on Species Abundance, Biomass Production, Wood Plant Density and Browsing Unit in an Albany Thicket of the Eastern Cape, South Africa

Sive Tokozwayo,Masibonge Gxasheka,Ayanda Kwaza,Thubela Thubela,Unathi Gulwa,Nobulungisa Mgujulwa,Amahle Sogoni,Nokonwaba Jokani,Thozama Theophilus Bozo,Yanga Mkabile,Siza Mthi,Nkululeko Nyangiwe

doi:10.4236/as.2022.131007

Abstract

Fire is regarded as management practice for maintaining grasslands and savannas. The vegetation occurring in fire prone areas becomes highly adapted to fire occurrences in savannas and grasslands. However, documentation on the influence of burning on vegetation is still limited in an albany thicket biome. The aim of the study was to evaluate the short-term influence of burning on species abundance, biomass production, wood plant density and browsing unit. Six plots (2500 m2) were demarcated; in each plot two parallel transects of 120 m2 with 5 m distance apart were measured. Three plots were burned in spring season, while no burning was done on the other remaining plots. Forty points per plot were obtained using step-point method to determine the relative abundance at burned and unburned plots. Woody plants occurred within a transect were identified, counted and recorded to determine density and browsing unit. Three quadrats (i.e. 0.25 m2) per plot were randomly laid within the transect; aboveground plant material within a quadrat were harvested. A total of 18 samples were harvested and oven dried at 60˚C for 48 hours to determine biomass production. The results showed that Themeda triandra (14%) and Panicum maximum (10%) were most abundant grass species at the burned plots. Burned plots had significantly higher biomass production (4804 kg/ha) compared to unburned plots (3641 kg/ha). Vachellia karoo (burned: 65.85% & unburn: 13.70%) and Searsia pallens (burned: 26.83% & unburned: 6.85%) were most dominant wood plant species at both burned and unburned plots. Burned plots had the highest browsing unit (3221 BU/ha) compared to unburned plots (2058 BU/ha). The decrease of woody plants at the burned plots proved that fire has a tremendous potential for managing woody plants. This study provided information on short-term influence of burning, however further long-term trials are required to determine the effects of burning.

Highlights

Bush encroachment is described as an increase in the abundance of woody vegetation and in savanna and grassland biomes [1]
The unburned site was dominated by mixed species which includes Panicum Maximum (15%), Themeda triandra (8%), Alloterpsis semialata (8%), Eragrostis curvula (9%), Melica Decumbens (8%) and forbs (13%)
This study revealed that unburned site (5112 plants/ha) had the highest density of woody plants compared to burned site (3485 plants/ha) (Figure 4)

Summary

Introduction

Bush encroachment is described as an increase in the abundance of woody vegetation and in savanna and grassland biomes [1]. Encroachment is perceived as the most extensive forms of degradation and a globally threat to the savanna and grassland biomes in both semi-arid and arid regions [2] [3] [4]. Ecologists perceived bush encroachment as a beneficiary in terms of carbon capture and storage [6]. It may permanently change the structure and functioning of savanna ecosystem [1]. Burning is done for removing grass litter or moribund, reducing tick infestation on grasses, controlling undesirable plants and improving grass quality in terms of nutrient content [8]

Objectives

Methods

Results

Conclusion