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 m 2) were demarcated; in each plot two parallel transects of 120 m 2 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 m 2) 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.
Bush encroachment is described as an increase in the abundance of woody vegetation and in savanna and grassland biomes [
The drivers of bush encroachment are complex to be understood, but are associated with overgrazing, climate related factors, exclusion of both burning and browsers [
Burning may also reduce light-limitations created by litter or woody plant cover, in that way grasses may receive more radiant energy which is vital for photosynthesis. Use of fire also improves nitrogen mineralization from organic matter [
Prescribed burning may suppress sapling from growing to maturity and producing seeds [
Bathurst burning trial is situated at 33˚32'42.83"S; 26˚50'25.24"E with elevation of 126 m, under Ndlambe Local Municipality in Sarah Baartman District (previously known as Cacadu District) of the Eastern Cape province (
terms of vegetation, Bathurst falls under the kowie thicket veld type (i.e. albany thicket biome) [
The research was conducted in the Eastern Cape at Bathurst Agricultural Research Station. In terms of grazing and browsing, the research was carried out in a protected area of the kowie thicket veld type. The experiment site was chosen since the vegetation was similar in terms of encroachment. Six plots were demarcated marked within the area 10 hectares, three of which were assigned to controlled burning and three of which were left unburned. The burning was done in early spring season before the first rain as suggested by [
Vegetation sampling was done at the beginning of spring prior burning in September 2019 (
Furthermore, grasses were classified according their ecological grouping, perenniality and nutritional value using Grasses of Southern Africa guide [
were oven dried at 60˚C for 48 hours [
A one-way ANOVA was performed using [
The relative abundance was calculated according to [
Relative abundance ( % ) = Number of individual species Number of species population × 1 00 %
Bush density was calculated according to [
BD = N WPT × S T
where BD = Bush density, NWPT = number of woody plants within the transect, ST = Size of the transect. Browsing unit was determined according to [
A total of 15 plant species were recorded, consisting of 31% decreasers, 25% increasers III, 25% increasers II, 13% increaser I and 6% forbs (
Fire changes plant communities by reducing the dominance of some plant species, but may also stimulate the growth of others [
Plants such as Melica decumbens, forbs and Elionorus muticus were less abundant at the burned site compared to unburned site, these plants may have
Relative abundance (%) | ||||
---|---|---|---|---|
Botanical name | Ecological status | Lifeform | Unburned | Burned |
Alloterpsis semialata | Increaser I | Perennial | 8 | 8 |
Aristida diffusa | Increaser III | Perennial | 1 | 2 |
Cymbopogon validis | Increaser I | Perennial | 2 | 3 |
Cynodon dactylon | Increasers II | Creeping | 5 | 10 |
Digitaria eriantha | Decreaser | Perennial | 5 | 9 |
Elionorus muticus | Increaser III | Perennial | 6 | 1 |
Eragrostis capensis | Increaser II | Perennial | 1 | 3 |
Eragrostis curvula | Increaser II | Perennial | 9 | 9 |
Forbs | Not known | Not known | 13 | 5 |
Helictotrichon turgidulum | Decreaser | Perennial | 4 | 6 |
Melica Decumbens | Increaser III | Perennial | 8 | 4 |
Microchloa Caffra | Increaser II | Perennial | 7 | 5 |
Panicum Maximum | Decreaser | Perennial | 15 | 10 |
Seteria sphacelata | Decreaser | Perennial | 4 | 6 |
Sporobolus africanus | Increaser III | Perennial | 4 | 5 |
Themeda triandra | Decreaser | Perennial | 8 | 14 |
been suppressed by fire at the burned site. The less abundance of forbs at the burned site compared to the unburned site, could be the fact that grasses may become more competitive and recovered faster after burning as compared forbs. This contradicts, [
Burned site had significantly (P < 0.05) higher biomass production (4804 kg/ha) compared to unburned site with the biomass production of 3641 kg/ha (
frequency and rainfall at burned regions. Furthermore, high dry matter yield at the burned confirms that fire has the stimulatory influence on the growth of some species and their litter production. Low dry matter production at unburned site may contributed by unremoved moribund around grass buds. The grass leaves grow from intercalary meristems and from new tillers from protected buds. Therefore, in the absence of fire tillers these may end up covered by moribund materials that could lead to slower growth rate of the vegetation in unburned areas [
Thirteen woody plant species were identified, 54% were acceptable (Brachylaena elliptica,Coddia rudis,Grewia occidentalis, Maytenus heterophylla,Scutia myrtia,Vachellia karoo) and 46% wereunacceptable (Diospyros lycioides,Lantana camara, Ptaeroxylon obliquum, Searsia pallens, Zanthoxylum capense and Trimeria trinervis) to browsers (
[
Relative abundance (%) | ||||
---|---|---|---|---|
Botanical name | Local name | Acceptability | Unburned | Burned |
Brachylaena elliptica | Isiduli | Acceptable | 4.11 | - |
Coddia rudis | Intsinde | Acceptable | 4.11 | - |
Diospyros lycioides | Umbhongisa | Unacceptable | 6.85 | 2.44 |
Grewia occidentalis | Umnqabaza | Acceptable | 31.51 | - |
Lantana camara | Utywala bentaka | Unacceptable | 9.59 | 3.66 |
Maytenus heterophylla | Umqaqoba | Acceptable | 1.37 | - |
Ptaeroxylon obliquum | Umthathi | Unacceptable | 1.37 | - |
Scutia myrtia | Isiphingo | Acceptable | 5.48 | 1.22 |
Searsia pallens | Intlolokotshane | Unacceptable | 6.85 | 26.83 |
Searsia incisa | Unongqutu | Acceptable | 6.86 | 1.22 |
Vachellia karoo | Umnga | Acceptable | 13.70 | 65.85 |
Zanthoxylum capense | Umnungwamabele | Unacceptable | 6.85 | - |
Trimeria trinervis | Indlebendlovu | Unacceptable | 1.37 | - |
intensity and fire tolerance. [
Albany thicket is characterized by two continuous layers of both grasses and woody plants [
[
Burned site had the highest browsing unit (3221 BU/ha) compared to unburned site with the browsing unit (2058 BU/ha) (
browsed by browsers at the height of 1.5 m. According to [
The results revealed that short-term burning yielded positive outcomes, and this was confirmed by the abundance of highly acceptable grasses (i.e. Themeda triandra, Panicum maximum, Cynodon dactylon and Digitaria eriantha) at burned site compared to unburned site. In terms of biomass production, similar trend was observed where burned site had more dry matter compared to unburned. However, short-term burning has shown potential for controlling or reducing wood plants as this was confirmed by significantly reduction of woody plant density at burned site. Burned site had high browsing unit compared to unburned site, which implies that most of the woody plants were within the reachable browsing height of 1.5 m for goats. This study recommends that further long-term trials need to be done to determine the effects of fire on rangeland vegetation.
The authors are indebted to the Bathurst and Dohne general workers for their assistance during the data collection and burning. We are also grateful to Dohne Agricultural Development Institute (ADI) and Department of Rural Development and Agrarian Reform (DRDAR) for permitting us to conduct this research.
The authors declare no conflicts of interest regarding the publication of this paper.
Tokozwayo, S., Thubela, T., Gxasheka, M., Mthi, S., Gulwa, U., Nyangiwe, N., Kwaza, A., Jokani, N., Mgujulwa, N., Mkabile, Y., Bozo, T.T. and Sogoni, A. (2022) 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. Agricultural Sciences, 13, 74-85. https://doi.org/10.4236/as.2022.131007