The population dynamics of some woody species in the kalahari sand vegetation of Hwange national park

A Dissertation Submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the Degree of Master of ScienceThe nopulaHon dynamics and principal controlling factors of six woody species found in the Kalahari Sand vegetation of Hwange Nation?1 Park are Investigated. The populations fror- woodland and sc areas of known human disturbance (logging) are compared with undisturbed sites. The effects of edaphic factors, frost-, fire and elephant damage on the woody species are examined. The results show the populations from the disturbed are?s vo be generally unstable with a decline in the woodlands. The estimated rerr litment of pluri lug a is 0,2 ?f the rate p.eedel to woodlands In the presen state* T1 influence of soil mo,svure is of major importance in determining vegetation 'hysiognomy an^ species composition. Frost and fire =*lso have a strong modifying influence on the vegetation through the differing sensitivities of each species. Frost, fire and elephant account for 57'''., and 19* of the damage (excluding unknown factors). In conclusion a hypo*-hes s showing *-he interaction of abiotic and bioMc factors on the three stages of vegetation cycling : woodland, scrub and grassland, Is presented

Bridging the divide between intuitive social-ecological value and sustainability in the Manica Highlands of southern Africa (Zimbabwe-Mozambique)

Southern African mountains remain poorly studied as social-ecological systems (SES) and are poorly represented in the global mountain discourse. However, these mountains provide essential ecosystem services (ES) that underpin local and regional development. Quantitative data on ES, their representation in policy, and the political will for sustainable management are limited. We demonstrate this using the Manica Highlands (MH; Zimbabwe—Mozambique): benefiting one million immediate and five million downstream beneficiaries, the seven identified ES are supported in the literature but lack recent quantitative data needed to persuade policymakers for action to promote sustainability. The ES are most at risk from mining, alien invasive species, rapid land transformation, and climate change – yet fine-scale quantitative data to inform mountain-specific policy on these are also lacking. We recommend a ‘science to policy to action’ agenda for the MH, but highlight that the greatest challenge to achieving sustainability is a lack of effective governance; therefore it may be difficult to change ‘immediate benefits’-thinking to higher ideals that would render the ES of the MH sustainable. As a result, academics, civic society, policy makers and governance instruments should work closely together to quantify the value of the MH, and to formulate specific policy for the MH.Travel and workshops (2015) were supported by the Swiss National Science Foundation (SNF; Grant No. IZ07Z0_160871), and a draft manuscript was supported by a South African National Research Foundation post-doctoral fellowship for VRC (2014–2016). The manuscript was completed with support from a University of the Free State (UFS) Afromontane Research Unit Post-doctoral Fellowship (for JDD), and publication costs were covered by the UFS.http://www.elsevier.com/locate/ecoser2020-10-01hj2019Plant Production and Soil Scienc

Large scale pre-rain vegetation green up across Africa

Information on the response of vegetation to different environmental drivers, including rainfall, forms a critical input to ecosystem models. Currently, such models are run based on parameters that, in some cases, are either assumed or lack supporting evidence (e.g., that vegetation growth across Africa is rainfall‐driven). A limited number of studies have reported that the onset of rain across Africa does not fully explain the onset of vegetation growth, for example, drawing on the observation of prerain flush effects in some parts of Africa. The spatial extent of this prerain green‐up effect, however, remains unknown, leaving a large gap in our understanding that may bias ecosystem modelling. This paper provides the most comprehensive spatial assessment to‐date of the magnitude and frequency of the different patterns of phenology response to rainfall across Africa and for different vegetation types. To define the relations between phenology and rainfall, we investigated the spatial variation in the difference, in number of days, between the start of rainy season (SRS) and start of vegetation growing season (SOS); and between the end of rainy season (ERS) and end of vegetation growing season (EOS). We reveal a much more extensive spread of prerain green‐up over Africa than previously reported, with prerain green‐up being the norm rather than the exception. We also show the relative sparsity of postrain green‐up, confined largely to the Sudano‐Sahel region. While the prerain green‐up phenomenon is well documented, its large spatial extent was not anticipated. Our results, thus, contrast with the widely held view that rainfall drives the onset and end of the vegetation growing season across Africa. Our findings point to a much more nuanced role of rainfall in Africa's vegetation growth cycle than previously thought, specifically as one of a set of several drivers, with important implications for ecosystem modelling

[Zavala's receipt of purchase from C. E. Childes, October 20, 1830]

Zavala's receipt of purchase from C. E. Childes: Philadelphia October 20, 183

Grazing behaviour of the giraffe in Hwange National Park, Zimbabwe

The giraffe (Giraffa camelopardalis) is usually described as an exclusive browser, feeding only on shrubs and trees, preferrably between 2 and 5 m above ground (Lamprey, 1963; McNaughton & Georgiadis, 1986; Ciofolo & Le Pendu, 2002). Although browsing seems to be an easier form of feeding for giraffes in terms of accessibility and vigilance (Young & Isbell, 1991), a few studies mention that the giraffe also ‘very occasionally’ feeds on grass (Pienaar, 1963; Du Toit, 2005). To be able to graze, a giraffe has to adopt the typical ‘drinking position’, where the forelegs are splayed out laterally, and sometimes the carpal joints are also flexed. In this position, the animals are particularly vulnerable to predators (Périquet et al., 2010). In this note, we show that grazing, although not a core activity, is a recurrent event in a nutrient-poor environment such as Hwange National Park and suggest a possible function