Browsing by Author "February, Edmund Carl"

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    The benefits and burdens of living beside the Cederberg Wilderness Area
    (2015) Wilson, John Martin Roy; Wynberg, Rachel Paula; February, Edmund Carl
    A great deal is riding on conservation efforts of the twenty-first century. In an era of extinction rates one thousand times faster than ever before, protected areas have emerged as the most widely used tool available to conservationists to curb the loss of species (Child, 2004; Jepson & Ladle, 2010) . The number and extent of protected areas has increased dramatically over the past century, and their future growth is guaranteed by international and national policies (Brockington et al., 2008). The growing prevalence of protected areas on a global landscape has increased contact between communities and conservation, frequently with conflict arising as a consequence (Dowie, 2009). Increasing recognition of the impact of protected areas on local people has given rise to international consensus is that there is a dearth of knowledge surrounding these implications which needs to be addressed (Brockington et al., 2006; Igoe, 2006; West et al., 2006) . It is this gap that this study sets out to ameliorate. The overarching aim of this research was to investigate the benefits and burdens that local communities experience from living beside a protected area. Further, this study also investigated the causes of these benefits and burdens, how they were distributed between communities at a local scale, and how local perception of the protected area was influenced as a result of these experiences. The Cederberg Wilderness Area, which has a history of restricting resource use dating back to the 1890s, was selected as the protected area of interest. Of the nine neighbouring communities, consideration of the origin and similarity between communities resulted in Bosdorp and Heuningvlei adopted as representatives for the study area. Household surveys, key informant interviews, observations and documentary evidence were utilised to obtain data, and triangulation was used across methods to validate findings (Jick, 1979). Household surveys and key informant interviews were conducted over two separate field visits between March and April, 2014. In particular, the findings of this study were considered in terms of the ecosystem services framework, as the dominant theory suggested in literature surrounding the benefits and burdens that people obtain from protected areas (CBD, 1992; Government of South Africa, 2010; MA, 2005). This study found that a total of 14 beneficial uses of natural resources provided directly or indirectly by the Cederberg Wilderness Area were enjoyed by the case study communities at a local scale. The distribution of these beneficial resource uses between the two communities varied widely, with just six of the 14 uses enjoyed in both communities. In addition to income generated directly by the Cederberg Wilderness Area through conservation and indirectly through tourism, participants agreed that they received benefits in terms of aesthetics, recreation, education, and spirituality. Seven burdens were raised by participants, with all but one shared between communities. However, the less economically able of the two communities, Heuningvlei, did experience a greater number and distribution of burdens than Bosdorp, the village from which most employees of the CWA originate, and the community who receive considerably more average monthly household income. Although all participants in Bosdorp disagreed with the statement that life would be better without rules associated with the Cederberg Wilderness Area, a third of Heuningvlei participants agreed therewith. The most noteworthy observation in terms of incongruence with the literature was the extent to which both communities benefited from the protected area. The reason suggested for this observation was twofold. First, the long history of living with resource restrictions in Heuningvlei has allowed the community to adjust its norms, values and practices in order to maximise benefit from the Cederberg Wilderness Area. Second, the establishment of the Bosdorp community in close proximity to the operational offices for the Cederberg Wilderness Area has allowed residents to maximise employment and other opportunities from the protected area. In order to ascertain the causes of the observations mentioned above, the findings were framed in terms of the ecosystem services framework. This framework was subsequently found to be ineffective in identifying these causes. However, all observations left unexplained by the ecosystem services framework were explained by adopting Access Theory (Ribot & Peluso, 2003). This highlighted the important role the communities played in realising ecosystem services, and allowed for an evaluation of the appropriateness of the ecosystem services framework for incorporating social dimensions in conservation approaches. In conclusion, it was ascertained that many of the findings observed in this study were highly contextual and more often determined by the social systems in question as opposed to ecological systems. Therefore, conservation approaches that aim to achieve more resilient systems must take these social systems into consideration. It was also concluded that the current dearth of information about the social implications of protected areas limits the utility of debates surrounding the need to take these implications into consideration in conservation practices, and poses a potential fatal flaw to conservation practices based on false assumptions of social systems. This study ends by calling for further research on this matter in order to achieve management approaches that result in resilient biodiversity conservation.
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    Climatic reconstruction using wood charcoal from archaeological sites
    (1990) February, Edmund Carl; Parkington, John
    This thesis assesses the feasibility of using wood charcoal from archaeological sites as a palaeoclimatic indicator. Three techniques are described: (i) charcoal identification from Xylem Anatomy. (ii) Ecologically Diagnostic Xylem Analysis and (iii) stable carbon isotope analysis on wood charcoal. The first is a well established method of environmental reconstruction. This is the first systematic application of Ecologically Diagnostic Analysis and the first application of stable carbon isotope analysis on wood charcoal. Charcoal identification shows that the most common woody species at Elands Bay today are also evident in the archaeological record over the last 4000 years, indicating a relatively stable plant community composition. Previous studies of wood anatomy have shown that there are links between vessel size, vessel number and climate. This study demonstrates that the wood anatomy of Rhus is not simply related to climatic factors, necessitating the employment of a wide range of statistical analytical techniques to identify climatic signals. In contrast, the anatomy of Diospyros shows strong correlations with temperature. Factor analysis of anatomical parameters of charcoal from Elands Bay archaeological sites indicates that there have been temperature changes over the last 4000 years. Stable carbon isotope ratios (¹³C/¹²C) of plants have been found to be a useful indicator of water use efficiency; plants in drier habitats exhibit more positive values than their more mesic relatives. The results of an isotopic analysis on modern wood charcoal show that ¹³C/¹²C ratios can be related to temperature and rainfall. The climatic component of the range in variation of ¹³C/¹²C in the archaeological record is not as easy to identify due to increased use of fossil fuels since the beginning of the Industrial Revolution. Indications are that wood charcoal does carry a climatic signal. A larger sample from more areas may give more dependable results.
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    Determining the potential drivers of invasive C4 grasses at De Hoop Nature Reserve, South Africa
    (2018) Munyai, Nthabeliseni Meryling; February, Edmund Carl; Bond, William John
    Grassland and shrubland distribution in SA is associated with rainfall seasonality. In grassland the vegetation is exclusively C4 while the shrub and tree component is generally C3. Shrublands, in contrast, are predominantly C3, for both woody and herbaceous species, though there can be a small C4 sedge and grass component. The C4 grassy biomes dominate the warm season rainfall region while C3 grasses predominate in the shrublands of the cool season rainfall regions. The C4 grasses are poorly competitive in cold climates. There are however anomalous patches of C4 grasses in cool season rainfall regions dominated by fynbos shrublands such as those at Potberg, De Hoop Nature Reserve, Overberg region, South Africa. Although the southern Overberg region receives rainfall year-round, more than half of the rain falls in the cooler months of the year. These C4 grassland patches appear to be invading the fynbos even on the nutrient poor podsols. The main objective of this study was to gain a better understanding of the ecology of these anomalous C4 grasslands in a fynbosdominated region. I first explored the role of roads as a conduit for grass invasion by sampling sites adjacent to and further away from the road verge. This was done by identifying all species in plots 5 m (Roadside pots) and 100 m (Adjacent plots) from the road verge every 500 m along a 14 km management road at Potberg. My results show that the most common C4 grasses were Cynodon dactylon and Eragrostis curvula whilst the most common C3 grass was Merxmuellera disticha. Both Roadside and Adjacent plots had more C4 grass species than C3 grasses. The frequency distribution of both C3 and C4 grass species was significantly higher on the Roadside plots than on the Adjacent plots. Although there was a higher incidence of C4 grass occurrence on the Roadside plots I conclude that, roadsides are not the conduit for C4 grass invasion into fynbos as several large patches of the C4 grass Eragrostis curvula and Imperata cylindrica can be found several kilometres away from the roadside and there are fewer C4 grasses away from the road verge. I then explored the impacts of C4 grasses on fynbos species diversity by identifying all the plants in 100 plots, half in fynbos-dominated vegetation and half in grassy patches. My results show that C4 grasses had a negative effect on fynbos species richness. The areas invaded by the C4 grass had fewer fynbos species (average of 7) compared to areas with C3 grasses (average 17). Some C4 grasses had more of an effect than others with some of the most aggressive the clonally spreading species Imperata cylindrica, Setaria sphacelata var. torta and Cynodon dactylon. C4 grasses such as Aristida diffusa and Themeda triandra occur naturally in the fynbos with little impact on fynbos species richness. Eragrostis curvula, a tall bunch grass, was also locally dominant in places at the expense of fynbos species diversity. To examine the drivers influencing colonisation of fynbos by C4 grass, I set up a transplant experiment designed to examine the extent to which topographic position along a slope (moisture availability), an increase in nutrient availability and a decrease in competition for resources influences the establishment and growth of C4 grass. To do this I transplanted tufts of Setaria sphacelata var. torta in three positions along a slope, with and without nutrient additions and with and without competition for soil resources. I removed competition for resources by trenching and inserting a plastic sheath around each grass tuft to a depth of 500 mm. My results show an increase in mortality in drier treatments at the top of the slope. Trenching and fertiliser addition had significant positive effects on grass biomass and negative effects on root shoot ratios. Slope position however only had significant effects on root shoot ratios. Plants at the top of the slope had significantly higher root/shoot ratios than those plants at the bottom (P<0.05). Trenching did not have a significant effect on root shoot ratios (P>0.05). Based on the results of this research, it can be concluded that the grass patches have a negative effect on fynbos species diversity. These grass patches are not a remnant from when the reserve was still a farm but are relatively new and are not invading out from the roads. I examined rainfall seasonality from 1910 to 2015 and found no change. My results from trenching show that physical disturbance that breaks up fynbos root systems will help promote C4 grass invasion. Thus, any activities that increases physical disturbance of the fynbos such as off-road vehicles and trampling by large mammals must be avoided to maintain intact fynbos. While this has not occurred at Potberg, I speculate that because of fire suppression, there has been a decline in species diversity and a reduction in competition for resources allowing the C4 grasses to establish and dominate. The impact of fire on C4 grass needs more research, to understand if too frequent or less frequent fire will disturb fynbos and allow invasion by C4 grasses.
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    Plant xylem anatomy, dendrochronology and stable carbon isotopes as tools in rainfall reconstruction in Southern Africa
    (1997) February, Edmund Carl
    Within South Africa there is a growing need for a high resolution proxy rainfall data set that goes back beyond the historic record. As a contribution to meeting this need four techniques for rainfall reconstruction are evaluated. It is only from a new technique utilising measurements of vessel size and frequency in the cross-sectional xylem anatomy of archaeological charcoal that statements may be made on rainfall trends over the last 2000 years. These results indicate a general decrease in rainfall from 2300 BP to the present with a slightly wetter period during the Little Ice Age (1300 to 1800 A.D.). The results also suggest that present conditions are much drier than at any other time within the last 2000 years. The only limitations on this method are the resolution of the radiocarbon dates, a suitable distribution of sites and a calibration curve for the species analysed.
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    Rapid leaf deployment strategies in a deciduous savanna
    (Public Library of Science, 2016) February, Edmund Carl; Higgins, Steven Ian
    Deciduous plants avoid the costs of maintaining leaves in the unfavourable season, but carry the costs of constructing new leaves every year. Deciduousness is therefore expected in ecological situations with pronounced seasonality and low costs of leaf construction. In our study system, a seasonally dry tropical savanna, many trees are deciduous, suggesting that leaf construction costs must be low. Previous studies have, however, shown that nitrogen is limiting in this system, suggesting that leaf construction costs are high. Here we examine this conundrum using a time series of soil moisture availability, leaf phenology and nitrogen distribution in the tree canopy to illustrate how trees resorb nitrogen before leaf abscission and use stored reserves of nitrogen and carbon to construct new leaves at the onset of the growing season. Our results show that trees deployed leaves shortly before and in anticipation of the first rains with its associated pulse of nitrogen mineralisation. Our results also show that trees rapidly constructed a full canopy of leaves within two weeks of the first rains. We detected an increase in leaf nitrogen content that corresponded with the first rains and with the movement of nitrogen to more distal branches, suggesting that stored nitrogen reserves are used to construct leaves. Furthermore the stable carbon isotope ratios (δ 13 C) of these leaves suggest the use of stored carbon for leaf construction. Our findings suggest that the early deployment of leaves using stored nitrogen and carbon reserves is a strategy that is integrally linked with the onset of the first rains. This strategy may confer a competitive advantage over species that deploy leaves at or after the onset of the rains.