scholarly journals The influence of the 1991/92 drought on the woody vegetation of the Kruger National Park

Koedoe ◽  
1995 ◽  
Vol 38 (2) ◽  
Author(s):  
A.J. Viljoen

All observations and data related to the impact of the 1991/92 drought on the woody vegetation, excluding the riverine vegetation of major rivers, are summarised. This includes data from a visual estimate of damage from aerial photographs, surveys on selected sites, and general observations. Despite lower rainfall, the area north of the Olifants River (excluding the far-northern part) was less affected than the area south of it, suggesting that the woody vegetation in the north is more adapted to drought. A characteristic of the drought was the localised distribution pattern and variable intensity of damage to the same species in the same general area. Information on 31 species are presented briefly. Although a large number of woody species was to some extent damaged, when the woody vegetation is considered as a whole, the influence of the drought was not very severe.

Koedoe ◽  
2016 ◽  
Vol 58 (1) ◽  
Author(s):  
Corli Coetsee ◽  
Benjamin J. Wigley

This study explores the impact of browsers on vegetation types within the Mapungubwe National Park and specifically whether rocky outcrops or ridges in the park serve as refugia from browsers, particularly elephants. We sampled 80 transects at 20 sites and recorded 1740 plants comprising 65 species. We found that a high proportion (> 80%) of the woody vegetation sampled indicated browser utilisation. Although certain woody species (e.g. Albizia harveyi, Boscia albitrunca, Lannea schweinfurthii) appeared to be preferred by browsers, browsing levels were relatively high among all woody species. High levels of browsing by herbivores other than elephants suggest that they have a significant impact on the park’s vegetation. We did not find that rocky ridges acted as refugia to browsers, but instead found that vegetation in rocky ridges was more severely impacted by browsers than vegetation in flat areas, despite vegetation being more accessible in flat areas. If elephant numbers continue to increase at the current rate (e.g. elephant numbers doubled between 2007 and 2010), we predict that some of the heavily utilised species will become locally rare over time.Conservation implications: High levels of browsing by both elephant and smaller herbivores contribute to significant impacts on vegetation away from rivers in Mapungubwe National Park. Without management interventions that address both types of impact, structural and species diversity are bound to decrease over the short to medium term.


2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Kiros Tsegay Deribew

AbstractThe main grassland plain of Nech Sar National Park (NSNP) is a federally managed protected area in Ethiopia designated to protect endemic and endangered species. However, like other national parks in Ethiopia, the park has experienced significant land cover change over the past few decades. Indeed, the livelihoods of local populations in such developing countries are entirely dependent upon natural resources and, as a result, both direct and indirect anthropogenic pressures have been placed on natural parks. While previous research has looked at land cover change in the region, these studies have not been spatially explicit and, as a result, knowledge gaps in identifying systematic transitions continue to exist. This study seeks to quantify the spatial extent and land cover change trends in NSNP, identify the strong signal transitions, and identify and quantify the location of determinants of change. To this end, the author classifies panchromatic aerial photographs in 1986, multispectral SPOT imagery in 2005, and Sentinel imagery in 2019. The spatial extent and trends of land cover change analysis between these time periods were conducted. The strong signal transitions were systematically identified and quantified. Then, the basic driving forces of the change were identified. The locations of these transitions were also identified and quantified using the spatially explicit statistical model. The analysis revealed that over the past three decades (1986–2019), nearly 52% of the study area experienced clear landscape change, out of which the net change and swap change attributed to 39% and 13%, respectively. The conversion of woody vegetation to grassland (~ 5%), subsequently grassland-to-open-overgrazed land (28.26%), and restoration of woody vegetation (0.76%) and grassland (0.72%) from riverine forest and open-overgrazed land, respectively, were found to be the fully systematic transitions whereas the rest transitions were recorded either partly systematic or random transitions. The location of these most systematic land cover transitions identified through the spatially explicit statistical modeling showed drivers due to biophysical conditions, accessibility, and urban/market expansions, coupled with successive government policies for biodiversity management, geo-politics, demographic, and socioeconomic factors. These findings provide important insights into biodiversity loss, land degradation, and ecosystem disruption. Therefore, the model for predicted probability generally suggests a 0.75 km and 0.72 km buffers which are likely to protect forest and grassland from conversion to grassland and open-overgrazed land, respectively.


2016 ◽  
Vol 19 (2) ◽  
pp. 265-286 ◽  
Author(s):  
GUILLAUME LETURCQ

Abstract The environmental impacts of hydroelectric dams in Brazil are investigated in local and regional scales, for the last years. In this paper, we analyze the impact than the establishment of a hydroelectric dam has for the people and their spaces, with the comparative experiences occurred for the North and South of Brazil. We will focus on aspects related to the organization of families, social fight, the compensation and resettlement of people affected by the dam's construction, as well we take a look to the similarities between the two areas, with emphasis on aspects related to migration, mobility and landscapes. For this, we rely on research carried out on the river Uruguay (South), based on interviews, questionnaires and studies of primary and secondary sources, from 2007 to 2014 and also in a survey that is currently being held in Belo Monte area (North), which also uses primary and secondary sources, with fieldwork periods.


Koedoe ◽  
1991 ◽  
Vol 34 (2) ◽  
Author(s):  
I. Thrash ◽  
P.J. Nel ◽  
G.K. Theron ◽  
J. Du P. Bothma

Quantitative inventory surveys were done on the woody vegetation in permanently marked plots at distance intervals from the Wik-en-Weeg Dam, Kruger National Park, in 1973. The surveys were repeated in 1990 so that changes in the community composition, the density and the canopy cover and the survival of the woody vegetation could be determined in relation to distance from the dam. Relationships with distance from the dam were shown for the relative density ofCombretumapiculatum in all height classes, the relative canopy cover of the second height class of woody plants, the relative canopy cover of C. apiculatum plants, the survival of all height classes of woody plants and the survival of C. apiculatum and Colophospermum mopane plants. It was concluded that the provision of water for game at the Wik-en-Weeg Dam had an impact on the woody vegetation in the vicinity. The relationships of parameters of the two dominant species, Combretum apiculatum and Colophospermum mopane, with distance from the dam were compared. Combretum apiculatum parameters were more sensitive to impact associated with the dam than those of Colophospermum mopane.


Land ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 122 ◽  
Author(s):  
Meyer ◽  
Holloway ◽  
Christiansen ◽  
Miller ◽  
D’Odorico ◽  
...  

Savannas are extremely important socio-economic landscapes, with pastoralist societies relying on these ecosystems to sustain their livelihoods and economy. Globally, there is an increase of woody vegetation in these ecosystems, degrading the potential of these multi-functional landscapes to sustain societies and wildlife. Several mechanisms have been invoked to explain the processes responsible for woody vegetation composition; however, these are often investigated separately at scales not best suited to land-managers, thereby impeding the evaluation of their relative importance. We ran six transects at 15 sites along the Kalahari transect, collecting data on species identity, diversity, and abundance. We used Poisson and Tobit regression models to investigate the relationship among woody vegetation, precipitation, grazing, borehole density, and fire. We identified 44 species across 78 transects, with the highest species richness and abundance occurring at Kuke (middle of the rainfall gradient). Precipitation was the most important environmental variable across all species and various morphological groups, while increased borehole density and livestock resulted in lower bipinnate species abundance, contradicting the consensus that these managed features increase the presence of such species. Rotating cattle between boreholes subsequently reduces the impact of trampling and grazing on the soil and maintains and/or reduces woody vegetation abundance.


Koedoe ◽  
2014 ◽  
Vol 56 (1) ◽  
Author(s):  
Gregory A. Kiker ◽  
Rheinhardt Scholtz ◽  
Izak P.J. Smit ◽  
Freek J. Venter

Woody plant cover and species composition play an important role in defining the type and function of savanna ecosystems. Approximately 2000 sites in the Kruger National Park (KNP) were surveyed by F.J. Venter over a period from 1985 to 1989, recording vegetation, soil and topological characteristics. At each of these sites (approximately 20 m × 20 m each), woody vegetation cover and species were recorded using a rapid, Braun-Blanquet classification for three height classes: shrub (0.75 m – 2.50 m), brush (2.50 m – 5.50 m) and tree (> 5.50 m). The objective of this study was to re-analyse the vegetation component of the field data, with a specific focus to provide a spatially explicit, height-differentiated, benchmark dataset in terms of species occurrence, species richness and structural canopy cover. Overall, 145 different woody species were recorded in the dataset out of the 458 species documented to occur in the park. The dataset describes a woody layer dominated by a relatively small number of widely occurring species, as 24 of the most common woody species accounted for all woody species found on over 80% of all sites. The less common woody species (101) were each recorded on 20 sites or less. Species richness varied from 12 to 1 species per site. Structural canopy cover averaged 9.34%, 8.16% and 2.89% for shrub, brush and tree cover, respectively. The dataset provides a useful benchmark for woody species distribution in KNP and can be used to explore woody species and height class distributions, as well as comparison with more recent or future woody vegetation surveys.Conservation implications: The results provided evidence that large-scale, woody vegetation surveys conducted along roads offer useful ecosystem level information. However, such an approach fails to pick up less common species. The data presented here provided a useful snapshot of KNP woody vegetation structure and composition and could provide excellent opportunities for spatio-temporal comparisons.


Koedoe ◽  
1995 ◽  
Vol 38 (2) ◽  
Author(s):  
Y. Buermann ◽  
H.H. Du Preez ◽  
G.J. Steyn ◽  
J.T. Harmse ◽  
A. Deacon

Silt loads in the Olifants and Sabie river systems inside the Kruger National Park, were monitored by collecting water samples every consecutive week for a period of 20 months. The variation in silt concentration, changes in selected physico-chemical water quality variables and fish mortalities during flushing (i.e. release of silt, by sluicing) of the Phalaborwa Barrage, were also monitored. The Olifants River inside the Kruger National Park carried high silt loads in summer; in the dry season the suspensoid load was greatly reduced. A similar pattern was observed in the Sabie River, but the silt loads were generally lower. It was apparent that silt loads released from the Phalaborwa Barrage led to large variations in the natural silt loads of the Olifants River. These increased amounts of silt (25 000 mg/1 to >70 000 mg/1) caused drastic reductions in the dissolved oxygen concentration of the water, ranging from >6 mg/1 to 0 mg/1. Depending on the severity and duration of the flushing, fish succumb to such silt loads. These findings, as well as published information, indicate that the management strategy of flushing to improve storage capacity is ecological unacceptable. It is therefore suggested that the use of the Phalaborwa Barrage as a future reservoir should be critically re-evaluated.


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