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Population growth and environmental shifts have elevated the pressure on land use and cover (LULC), necessitating vital management and adaptive strategies to preserve the balance between ecosystem services and human well-being in watersheds. It's pivotal to understand the implications of human-induced shifts from natural to human-dominated surroundings This study utilized Google Earth Engine (GEE) to analyze 31 years of LULC changes in Letaba watershed. Using GEE's random forest, LULC classes were mapped with 93% to 99% accuracy across four timeframes (1990, 2000, 2010, and 2021). Trends revealed declining water bodies (-4%), bare surfaces (-2%), natural forest (-3%), and grassland (-3%), while shrublands, plantations, and built-up areas increased at annual rates of 41%, 24%, and 47% respectively. This transformation reflects population-driven shifts, necessitating adaptive strategies. Given the importance of plantations for income, embracing climate-smart agriculture could ensure long-term food and environmental security, thus addressing the evolving dynamics in Letaba watershed. [ABSTRACT FROM AUTHOR]

Concerns about the growing pied crow I Corvus albus i population in southern Africa over the last 30 years (Cunningham et al., 2016) stem from the potential impacts on other species. Routes are displayed over a 30-m resolution raster of normalised difference vegetation index (NDVI) ranging from 0.01 (light grey) to 0.15 (dark grey) gl When multiple crows were observed, we only recorded the distance to the first crow spotted, which admittedly may introduce bias that suggests our density values (see results) are underestimated. We conducted road transects in Dronfield and Mokala and first developed a distance density function to determine how the probability of spotting pied crows changes with distance away from the observer along these transects. When a pied crow was detected, we stopped the car and recorded crow frequency and the perpendicular distance (in metres) between the crow(s) and the transect (i.e. distance sampling). [Extracted from the article]

Existing efforts to continuously monitor land cover change using satellite image time series have mostly focused on forested ecosystems in the tropics and the Northern Hemisphere. The notable difference in spectral reflectance that occurs following deforestation allows land cover change to be detected with relative accuracy. Less progress has been made in detecting change in low productivity or disturbance-prone vegetation such as grasslands and shrublands where natural dynamics can be difficult to distinguish from habitat loss. Renosterveld is a hyperdiverse, critically endangered shrubland ecosystem in South Africa with less than 5–10% of its original extent remaining in small, highly fragmented patches. I demonstrate that classification of satellite image time series using neural networks can accurately detect the transformation of Renosterveld within a few days of its occurrence and that trained models are suitable for operational continuous monitoring. A dataset of precisely dated vegetation change events between 2016 and 2021 was obtained from daily, high resolution Planet Labs satellite data. This dataset was then used to train 1D convolutional neural networks and Transformers to continuously detect land cover change events in time series of vegetation activity from Sentinel 2 satellite data. The best model correctly identified 89% of land cover change events at the pixel-level, achieving a f-score of 0.93, a 79% improvement over the f-score of 0.52 achieved using a method designed for forested ecosystems based on trend analysis. Models have been deployed to operational use and are producing updated detections of habitat loss every 10 days. There is great potential for continuous monitoring of habitat loss in non-forest ecosystems with complex natural dynamics. A key limiting step is the development of accurately dated datasets of land cover change events with which to train machine-learning classifiers. [ABSTRACT FROM AUTHOR]

Specific trait–environment interactions have led to globally unusual botanical radiations in the Cape Floristic Region (CFR) of South Africa. Yet it is unclear whether such interactions have similarly resulted in the diversification of the fauna independently of associations with plants.We explore this question for the Collembola genus Seira, which includes 89 species in the CFR, and appears to have diversified substantially into warm, dry fynbos shrublands—habitats atypical of those usually occupied by Collembola. Specifically, we determine whether thermal tolerance is higher for members of the genus in these shrublands compared with congeners in cooler, moister Afrotemperate Forests in the region, and with Collembola globally.Fynbos‐inhabiting Seira species have remarkable critical thermal maxima (CTmax) of on average 43°C, 5–6°C higher than congeners occupying the Southern Afrotemperate Forests, and Collembola globally, even when taking CTmax variation associated with regional climate into consideration.Thermal tolerance trait variation among the Seira species from different habitats is likely the consequence of variation in habitat temperature: fynbos shrublands are on average ~17°C warmer than Afrotemperate Forests. Moreover, periodic fires in the fynbos have a large effect on microhabitat temperatures, increasing them substantially (by ~7.5°C) in the year after fire, which may be especially relevant in selecting for higher thermal tolerance in species from this habitat.These results suggest that the remarkable richness of Seira in the CFR may in part be due to the evolution of very high CTmax values which have enabled them to take advantage of a hot, dry habitat that is unusual for Collembola. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

The long-term effectiveness of ecological restoration projects is seldom reported in the scientific literature. This paper reports on the outcomes of ecosystem restoration following the clearing of alien Pinus plantations and associated alien plant invasions over 13 years from an 8000 ha mountain catchment in the Western Cape Province, South Africa. We examined the goals, methods and costs of management, and the ecological outcomes in terms of reduced alien plant cover and native vegetation recovery. While the goals were not explicitly formulated at the outset, they were implicitly focussed on the conservation of water resources, the restoration of biodiversity, and the provision of employment. Initially, most (>90% of the area) was occupied by Pinus and Acacia invasions, mostly at low densities. The cost of control (initial clearing and up to 16 follow-up visits to remove emergent seedlings) amounted to almost ZAR 50 million (14 ZAR ∼ 1US$). Although the cover of alien plants was greatly reduced, over 1000 ha still support dense or medium invasions (>25% cover), and the area occupied by scattered Pinus plants increased by over 3000 ha to >5700 ha. A reliance on passive restoration had not yet resulted in full recovery of the natural vegetation. The mean number of species, and total projected canopy cover on 50 m 2 plots was lower in cleared than in comparable reference sites with pristine vegetation (21 vs 32 species/plot, and 94 vs 168% cover respectively). While the project is ongoing, we conclude that the entire area could revert to a more densely-invaded state in the event of a reduction of funding. Several changes to the management approach (including the integrated use of fire, a greater use of power tools, and active re-seeding of cleared areas with indigenous shrubs) would substantially increase the future effectiveness of the project and the sustainability of its outcomes. [ABSTRACT FROM AUTHOR]

Aim Climate change and other anthropogenic global change drivers act in complex, mutually exacerbating ways to alter the abundance and distribution of species. In South Africa, pied crows Corvus albus have increased in numbers and range in recent decades. Popular opinion links these changes to urbanisation and infrastructure development, but there has been no empirical test of this idea. We aimed to clarify the drivers of pied crow population changes in South Africa. Location South Africa. Methods We used publicly available long-term datasets, the Southern African Bird Atlas Project and University of Delaware Gridded Climate Database, and spatial data from government bodies, to assess relationships between pied crow population and range changes, land use, infrastructure, urbanisation and climate change. Results Pied crow numbers have increased significantly in the past three decades, but rate of increase varied geographically, with crows declining in the northeast and increasing in the south-west of South Africa. Pied crow population changes were strongly correlated with climate change. Crows have benefited most from climate warming in the shrubland biomes of south-western South Africa. Pied crows are tree nesters, and within these shrublands, there is a strong positive relationship between the rate of population increase and the density of powerline infrastructure, which may facilitate pied crows' increase by providing nesting sites. Main conclusions Pied crow numbers have increased in response to climate warming, with their spread facilitated by electrical infrastructure in south-western South Africa, providing a clear example of compound influence of multiple global change drivers promoting a significant change in species range and reporting rate. Pied crows are generalist predators and there is popular concern about their ecological impact in areas where increases have occurred. We highlight the importance of understanding the ecosystem-level implications of increased numbers of pied crows in South Africa's shrubland biomes. [ABSTRACT FROM AUTHOR]

The Afrotropical two-eyed orange lungless spider genus Diploglena Purcell, 1904 is revised. Both sexes of the South African type species, D. capensis Purcell, 1904, are redescribed, as well as the females of the Namibian subspecies D. capensis major Lawrence, 1928. The males of this species are described for the first time, and it is elevated to species level as D. major stat. n.; it is also recorded from Botswana and South Africa for the first time. Four new species are described: D. arida sp. n., D. dippenaarae sp. n. and D. proxila sp. n. from South Africa, and D. karooica sp. n. from South Africa and Namibia. All of the species are distributed in arid and semi-arid vegetation types, including desert, Nama and Succulent Karoo, fynbos and dry savannahs. [ABSTRACT FROM AUTHOR]

Invasive alien plants (IAPs) are regarded as the leading ecological threat to the recently established Garden Route National Park (GRNP) along the Cape south coast of South Africa. The extensive and long-standing presence of commercial forestry in the region has contributed substantially to the current load of IAPs in the area. The GRNP's fragmented, linear configuration and a multitude of anthropogenic and ecological disturbances in the landscape contribute to its susceptibility to alien plant invasion. In compiling a checklist of alien flora for the park, we recorded 244 species of alien plants in 77 families, of which 58% (141 species) have not been recorded for the region by the Southern African Plant Invaders Atlas. Of the GRNP alien plant species, 9% are casual aliens, 27% naturalised, 59% invasive, and 5% transformers. Among South African National Parks, the GRNP ranks second in terms of alien plant species richness and has the largest proportion of invasives and transformers for those parks where invasion status was recorded. Transformer species in the GRNP are almost exclusively tree species introduced from Australasia > 100 years ago for forestry purposes or sand stabilisation. Natural habitat within the park that is most threatened by IAPs is fynbos shrublands and riparian habitat. Our analysis indicates that the pressure of IAPs in the GRNP is escalating. Substantial and sustained management actions will be required to mitigate impacts from alien plant invasions in the GRNP. We identified species posing emerging or escalating threats that require improved control or regulation. [ABSTRACT FROM AUTHOR]

We examined whether extensive dry season dieback and mortality in a South African fynbos community were due to drought or pathogen attack. Plant dieback and mortality have been reported elsewhere in similar plant communities suggesting potential for a widespread climatic or biotic threat to this community. We collected tissue samples from Brunia noduliflora, the dominant plant in the community, and cultured them for potential plant pathogens. We also measured dry season predawn and midday water potentials of healthy and stressed plants and constructed pressure-volume curves to assess turgor loss point. Plant stress and mortality were monitored over a 2-year study period. Both healthy plants and plants that displayed moderate signs of stress had dry season predawn water potentials well above their turgor loss point suggesting plants were not water stressed. However, plants displaying >60% crown dieback had much lower water potentials (as low as −12 MPa). A previously undescribed fungus ( Pythium sp.) was isolated from the root vascular tissue of all stressed plants and was not present in healthy plants. The proximate cause of plant stress was likely pathogen-induced, while the ultimate cause of plant death appears to be extreme water stress. The present study suggests that Brunia (Bruniceae), Leucadendron (Proteaceae) and Erica (Ericaceae), all emblematic and dominant genera within the diverse fynbos community, may be susceptible to Pythium infection. This may pose a serious threat to communities already threatened by climate change. [ABSTRACT FROM AUTHOR]

Two new species of Neanurinae (Collembola) are described from the Western Cape, South Africa: Ectonura monochaeta sp. n. and Ectonura barrai sp. n. E. monochaeta sp. n. differs from other species in the genus by its strongly reduced chaetotaxy, and the lateral shift of dorso-internal chaetae on Abd. V and their integration in the tubercles (De+DL). E. barrai sp. n. is similar to E. natalensis (Womersley, 1934), but differs in chaetotaxic details and chaetal group arrangement. A key to the seven species of Neanurinae recorded from South Africa is given. [ABSTRACT FROM AUTHOR]

1. Fire is an important process in Mediterranean-ecosystem shrublands, and prescribed burning is often used to manage these ecosystems. Analyses of past fire regimes are required to interpret biotic responses to fire, as well as to assess the degree to which management interventions have been able to influence the fire regime. 2. We used a spatial data base of fires within 10 protected areas covering >720 000 ha to examine the frequency, seasonality, size and cause of fires over four decades. Our study covered five fire climate zones and a range of mountain fynbos shrubland types. We examined whether regular prescribed burning would be necessary to rejuvenate the vegetation, and also to reduce the incidence and extent of wildfires. 3. Cumulative fire frequency distributions indicated that the probability of fire was not strongly affected by post-fire age, with 50% of the area experiencing a successive fire within 10–13 years after the previous fire in most areas. This suggests that the accumulation of fuel did not limit the occurrence of wildfires, and that regular prescribed burning would not necessarily reduce the risk of wildfires. 4. Inland zones experienced more severe fire weather than coastal zones (∼35% vs. 11–19% of days with high to very high fire danger, respectively). Despite these differences, fire return periods were similar (10–13 years), suggesting that the availability of ignitions, and not fuel or weather, limited the occurrence of wildfires. 5. Despite a policy that promoted prescribed burning, a relatively small area (between 4·6% and 32·4% of the area of all fires) burned in prescribed burns. Seasonal restrictions for safety and ecological reasons, the imperative to integrate planned fires with invasive alien plant treatments and unplanned wildfires have all contributed to the relatively small area that burnt in prescribed burns. 6. Synthesis and applications. Recurrent wildfires,... [ABSTRACT FROM AUTHOR]

During a recent survey of Penicillium spp. from fynbos soils in the Western Cape Province of South Africa, several undescribed species were isolated. Similar isolates of one of these species also were collected in the Western Cape from Protea infructescences. These strains were compared morphologically to known species of Penicillium but could not be identified with previously published keys. Morphologically these strains belong to subgenus Biverticillium. They are distinguished by strongly funiculose colonies covered by glutinous exudates and conidiophores with thin acerose phialides (8.5-10[-12] x 2.0 2.5 µm) that give rise to chains of subspheroidal to ellipsoidal conidia (2.5-3.0 x 1.5-2.5 µ-m). Charateristically short (100-150[-250] µm) determinate synnemata are produced in culture after prolonged incubation with much longer synnemata produced in nature. Based on differences in morphology and molecular characters, the strains are described here as Penicillium ramulosum sp. nov. [ABSTRACT FROM AUTHOR]

Over evolutionary time, the number of species in a community reflects the balance between the rate of speciation and the rate of extinction. Over shorter time-scales local species richness is also affected by how often species move into and out of the local community. These processes are at the heart of Hubbell's ‘unified neutral theory of biodiversity’ ( Hubbell 2001 ). Hubbell's spatially implicit, dispersal-limited neutral model is the most widely used of the many implementations of neutral theory and it provides an estimate of the rate of speciation in a metacommunity (if metacommunity size is known) and the rate at which species migrate into the local community from the wider metacommunity. Recently, this neutral model has been used to compare rates of speciation and migration in the species-rich fynbos of South Africa and in neotropical forests. Here we use new analytical methods for estimating the neutral model's parameters to infer speciation and dispersal rates for three sites in species-rich sclerophyll shrublands (equivalent to fynbos) in Western Australia (WA). Our estimates suggest that WA shrublands are intermediate between fynbos and tropical rainforest in terms of speciation and dispersal. Although a weak test, the model predicts species abundance distributions and species accumulation curves similar to those observed at the three sites. The neutral model's predictions also remain plausible when confronted with independent data describing: (1) known edaphic relationships between sites, (2) estimates of metacommunity species richness and (3) rates of speciation among resprouters and nonsprouters. Two of the site pairs, however, show species turnovers significantly different from those predicted by the spatially implicit form of the neutral model that we use. This suggests that non-neutral processes, in this case probably edaphic specialisation, are important in the WA shrubland metacommunity. The neutral model predicts similar rates of speciation in resprouter and sprouter taxa, a finding supported by recent molecular phylogenies. Finally, when converted into temporally scaled speciation rates and species longevities, the estimates produced by the neutral model seem implausible. The apparent departure from neutrality in the turnover of species between some sites and the implausible temporal dynamics may be due to the particular model chosen and does not reduce the significance of our other results, which confirm that local dispersal limitation, coupled with broader scale edaphic fidelity, combine to structure this biodiverse metacommunity. [ABSTRACT FROM AUTHOR]

Research in Mediterranean-climate shrublands in both South Africa and Australia shows that recruitment of proteoid shrubs (non-sprouting, serotinous Proteaceae) is best after warm-season (summer and autumn) fires and worst after cool-season (winter and spring) ones. This pattern has been attributed to post-dispersal seed attrition as well as size of pre-dispersal seed reserves. Here we investigate patterns of post-fire recruitment for four proteoid species in the eastern part of South Africa's fynbos biome, which has a bimodal (spring and autumn) rainfall regime. Despite the lack of significant differences in recruitment between cool- and warm-season burns, we find some evidence for favourable recruitment periods following fires in spring and autumn, immediately before, and coinciding with, the bimodal rainfall peaks. This suggests that enhanced recruitment is associated with conditions of high soil moisture immediately after the fire, and that rapid germination may minimize post-dispersal seed attrition. In two of the species, we also find a shift from peak flowering in winter and spring in the Mediterranean-climate part of the fynbos biome, to summer and autumn flowering in the eastern part. Because these two species are only weakly serotinous, warm-season flowering would result in maximal seed banks in spring, which could explain the spring recruitment peak, but not the autumn one. We conclude that eastern recruitment patterns differ significantly from those observed in the western and central parts of the biome, and that fire management protocols for the east, which are currently based on data and experience from the winter-rainfall fynbos biome, need to be adjusted accordingly. Fire managers in the eastern fynbos biome should be less constrained by requirements to burn within a narrow seasonal range, and should therefore be in a better position to apply the required management burns. [ABSTRACT FROM AUTHOR]

Golf courses and estates are one form of development threatening coastal vegetation in South Africa's Cape Floristic Region. They occupy substantial tracts of land, fragmenting indigenous vegetation. This study investigates the effects on bird community structure and function of replacing natural Strandveld vegetation with a 170-ha golf estate in which 46 ha of Strandveld vegetation was retained in conditions ranging from pristine to moderately degraded. Bird assemblages of the remaining Strandveld patches in the golf estate were compared with those of an adjacent Strandveld conservation area. Field work was conducted during the birds' breeding season, in October and November 2005. The golf estate was more species rich overall, but many species were uncommon, several were present only as a consequence of the creation of new habitats, and species were not evenly distributed across the remaining Strandveld fragments. Bird diversity and abundance were significantly higher in the adjacent conservation area. It is estimated that more than 8500 individual birds were displaced by construction of the golf estate and four Strandveld species were not represented at all within the estate. Within the estate, species richness rose with increasing Strandveld patch size and the minimum area of continuous pristine vegetation required to maintain the natural species assemblage was estimated at 51 ha. The golf estate was characterized by a high proportion of generalist and granivorous species, but at the cost of reduced numbers of frugivores and nectarivores. Energy flow through the bird communities in the two areas was thus markedly different, and pollination and fruit dispersal potential within the golf estate were reduced substantially. Golf courses and golf estates inevitably will not substitute for the natural habitats they have replaced, but careful design with input from ecological theory can reduce the adverse effects of fragmentation. [ABSTRACT FROM AUTHOR]

1. Gradients of animal impact known as piospheres tend to develop around artificial watering points, particularly in arid zones. Such grazing gradients represent a potential opportunity for differentiating the long-term effects of livestock activity from other environmental patterns. In this study, the impact of watering point provision on the plant cover, species richness and community structure of Karoo shrublands, South Africa, was investigated in the context of the evolutionary history and current grazing management practices of the region. 2. The impacts of watering point provision were investigated by sampling plant cover and composition along transects placed at set distances, ranging from 10 m to 2200 m, from 11 watering points. 3. Karoo vegetation cover and structure are relatively resilient to livestock grazing. Karoo plant diversity, as measured by species richness, evenness and dominance, was not as resilient. Twice as many species decreased as increased near watering points. The majority of species that decreased were regarded as being highly palatable to livestock. Heavy grazing, leading to death or repeated reproductive failure, is the most likely mechanism leading to the decline of such species. 4. The highly disturbed area immediately adjacent to watering points was dominated by forbs and contained a large proportion of alien species. Adjacent to this was a zone dominated by widespread shrub species of medium to low palatability. Areas most distant from watering points contained a greater proportion of species known to be highly palatable to livestock. The ability of dominant Karoo shrubs to tolerate heavy grazing may have allowed rangeland managers to maintain stocking rates above that which can be tolerated by the majority of species but which are supported by a minority of grazing-tolerant species. 5. Synthesis and applications. Highly palatable species are more abundant in areas distant from water points. Larger paddocks therefore provide a refuge for sensitive species that might otherwise be lost from the rangeland as a whole. Species that tend to occur away from watering points represent potentially useful indicators of grazing pressure. The use of these species as indicators of rangeland condition among landowners should be promoted. [ABSTRACT FROM AUTHOR]

Question: In semi-arid systems, rainfall gradients can cause plant-plant interactions to shift from negative to positive or vice versa. However, the importance of a second major abiotic factor, soil nutrients, has rarely been considered. We consider different combinations of both factors and ask: do net adultseedling interactions become less competitive and more facilitative with increasing overall abiotic harshness? Location: Succulent Karoo, Western Cape, South Africa. Methods: We examined the interactions between seedlings and adult shrubs at two sites. Sites differ in rainfall, and each contain two habitats: Nutrient-rich mounds associated with underground termitaria and a relatively nutrient-poor matrix. We carried out a spatial pattern analysis of community-wide seedling-adult associations. We then conducted field and greenhouse experiments to test the effects of soil and the presence of neighbouring shrubs on the growth and survival of six seedling species. Results: At the higher rainfall site, both competitive and facilitative effects of adults on seedlings were found but did not differ by habitat, despite the more benign conditions in the mound habitat. At the lower rainfall site, adult shrubs generally had neutral effects on seedlings in the matrix habitat. In the nutrient-rich mound habitat, however, adult shrubs had strong and consistently competitive effects on seedlings. Conclusion: Seedling-adult interactions could not be predicted by a simple overall gradient of abiotic harshness, demonstrating the need for more complex, mechanistic models to predict plant-plant interactions. We suggest that rainfall and soil nutrients affect seedling-adult relations through their interactive effects on the life-history attributes of the species [ABSTRACT FROM AUTHOR]

Smoke is an important factor involved in fire and post-fire germination cues. The role of smoke in stimulating germination was first highlighted in South Africa in a study on Audouinia capitata, a threatened fynbos species. Further studies on South African fynbos, Californian chaparral and Australian species have illustrated the widespread ability of smoke to promote germination of many species from fire-prone areas. However, smoke-stimulated germination is not limited to species from fire-prone habitats, and a variety of species from fire-free habitats also respond positively. Smoke and aqueous smoke extracts can potentially be used for a variety of applications related to seed technology. These include uses in horticulture, agriculture, ecological management and rehabilitation of disturbed areas. [ABSTRACT FROM AUTHOR]

Land cover change is the leading cause of global biodiversity decline. New satellite platforms allow for monitoring of habitats in increasingly fine detail, but most applications have been limited to forested ecosystems. I demonstrate the potential for detailed mapping and accurate dating of land cover change events in a highly biodiverse, Critically Endangered, shrubland ecosystem—the Renosterveld of South Africa. Using supervised classification of Sentinel 2 data, and subsequent manual verification with very high resolution imagery, I locate all conversion of Renosterveld to non-natural land cover between 2016 and 2020. Land cover change events are further assigned dates using high temporal frequency data from Planet labs. A total area of 478.6 hectares of Renosterveld loss was observed over this period, accounting for 0.72% of the remaining natural vegetation in the region. In total, 50% of change events were dated to within two weeks of their actual occurrence, and 87% to within two months. The Renosterveld loss identified here is almost entirely attributable to conversion of natural vegetation to cropland through ploughing. Change often preceded the planting and harvesting seasons of rainfed annual grains. These results show the potential for new satellite platforms to accurately map land cover change in non-forest ecosystems, and detect change within days of its occurrence. There is potential to use this and similar datasets to automate the process of change detection and monitor change continuously. [ABSTRACT FROM AUTHOR]

Deals with a study which attempted to model the distribution of communities and the fynbos/succulent karoo biome boundary in Matjiesrivier Nature Reserve in South Africa using several easily measurable environmental variables. Ecology of the Matjiesrivier Nature Reserve; Vegetation data in Matjiesrivier Nature Reserve; Application of the generalized linear models.

In the Mediterranean ecosystems of South Africa and Australia, the role of ants in the dispersal of seeds is well known and antagonistic interactions as well as myrmecochory occur. The high prevalence of seed dispersal by ants, environments. Ant dispersal has been considered unimportant in the Mediterranean region and , until now, no systematic study of ant-seed interaction has been undertaken. In the Mediterranean shrubland of Southern Italy the seed content of functioning nests of the ant Messor minor (André) has been quantitatively analyzed. The existence in the nest of seeds from shrub species, as well as those of the Fabacease and Poaceae, suggest that ant dispersal may be much more widespread in the Mediterranean environments than has been realized. A large proportion of the seeds came from fleshy-fruited shrub species previously reported to be bird dispersed, e.g. Rhamnus alaternus L., Myrtus communis L., Smilax aspera L., Pistacia lentiscus L. and Phillyrea latifolia L. Analysis of nest mounds showed that, although many seeds had been partially predated by the ants, a very large number had been collected, transported to the nest and subsequently removed to the mound without damage. Examination of the structure of the fruits and seeds of R. alaternus and M. communis, and summer fruiting phenology of R. alaternus, provided further evidence of specific adaptation to ant dispersal. The presence of an elaiosome on the seed is reported for the first time in both species. Feeding trials showed that ants selectively remove specific diasporas, preferentially collecting the seeds with the elaiosome. [ABSTRACT FROM AUTHOR]

1. The influence of seed availability, weather and microsite on natural emergence and survival of seedlings was investigated over 38 months in arid shrubland in the southern Karoo, South Africa, developed under <200 mm annual precipitation. 2. Small-scale clearing and herbivore exclusion experiments were conducted to test the hypotheses that seedling survival and growth were unaffected by competition and herbivory. 3. In undisturbed vegetation 20-800 seedlings m[SUP-2] emerged in the relatively cool and humid austral autumn. Densities of emerging seedlings were greater in microsites influenced by grazing, termitaria and plant litter than in undisturbed or exposed sites. The species composition of seedling assemblages resembled that of the vegetation. Survival varied from 5% in 1989 and 1990 to 25% in 1991, and appeared to be limited by the quantity of rain in winter and spring. 4. Vegetation clearing increased the amplitude of soil moisture oscillations at 50 mm below the soil surface, but reduced the rate of soil-moisture depletion at 150 mm below the surface. 5. The species composition of perennial seedlings in cleared vegetation was influenced by the original plant cover and the presence of plant litter on the soil surface. 6. Established plants had more influence on seedling survival than did grazing by wild animals or sheep. Proximity to mature perennials reduced both survival and growth of Karoo annuals and perennials. 7. Grazing by sheep and wild animals reduced the size, but not the survival, of perennial seedlings palatable to mammalian herbivores. Annual plants were larger and more abundant in clearings than in undisturbed shrubland. [ABSTRACT FROM AUTHOR]

Determines changes in biomass, size and distribution of plant parts as fuel and plant moisture and energy contents at two sites in South Africa invaded by the alien shrubs Hakea sericea and Acacia saligna. Use of the data to define fuel models and to simulate fire behavior using Rothermel's fire model.

Describes the behavior experimental fires in a South African fynbos, Macchia, vegetation and predictions from Rothermel's fire model. Comparison of results to fire behavior in other shrubland ecosystems; Greater fire spread rates and fire intensity in fynbos than in Scottish heathland.

Investigates the influence of annual and seasonal rainfall variability and systems of sheep grazing on the vegetation changes in a semi-arid, grassy dwarf shrubland in Karroo, South Africa. Use of ordination and bivariate methods; Temporal pattern of annual rainfall; Irruption of annual grasses during years with suitable rainfall; Influence of grazing on longer-lived plants.

(1) Random litterfall and litter production and decomposition of Leucospermum parile and Thamnochortus punctatus were monitored between 1981 and 1983 in a 5–7-yr old stand of coastal fynbos. south western Cape, South Africa. This vegetation has a characteristic physiognomy consisting of proteoid, ericoid and restioid elements. (2) Annual litter production was 84 and 72 g m-2 during 1981–82 and 1982–83 respectively with summer-autumn being the main period of litterfall; the major litter came from the ericoid elements. No differences were found in fats and waxes, soluble carbohydrates, soluble phenolics and total nitrogen between leaf litter of proteoid and ericoid elements and culm litter of the restioid elements. (3) Mean annual litter production under the canopies of L. parile was 357 and 429 g m-2 during 1981–82 and 1982–83. respectively, with 51-58% being leaf litter. Seasonal variations were found in the methanol-soluble carbohydrates (summer maximum) and lignin (winter maximum) in the leaf litter of JL, parile and a withdrawal of 41% nitrogen and 25-50% phosphorus was calculated during leaf abscission. (4) Female plants of T. punctatus had an annual litter production of 23 g m-2 compared with 12 g m-2 for males. The main litter category from both sexes was inflorescence parts. Holocellulose was the main organic constituent in fertile culm litter of both sexes of T. punctatus and the restioid group generally. (5) Turnover times of dry mass were calculated to be 14 5 and 114 yr for leaf litter of L. parile and sterile culms of T. punctatus, respectively, but male flowerheads of T. punctatus showed no significant decay. (6) Methanol-soluble carbohydrates, phenolics and holocellulose declined at approximately similar rates in decomposing leaves of L. parile. Changes in nitrogen and phosphorus contents in decomposing leaves of L. parile were negligible but accumulations of potassium, magnesium, calcium and iron were demonstrated. (7) These results are compared with those of other mediterranean type ecosystems. The frequent fires in the fynbos vegetation may preclude the development of a steady-state litter. [ABSTRACT FROM AUTHOR]

(1) The Clovelly soil studied under a mature coastal fynbos stand in the South-Western Cape, South Africa, showed low concentrations of exchangeable NH4+-N and NO3--N. (0.5–3.5 μg N g-1 for NH4+-N and 0.2–1.2 μg N g-1 NO3--N in the surface 10 cm) probably associated with the low total N content of this sandy soil. (2) The soil showed distinct gradients of decreasing quantities of organic matter, total N, exchangeable NH4+-N and NO3--N with depth. There was a linear relationship between organic matter content and total N concentration in the surface 100 cm. (3) Lateral differences in total N concentrations were not apparent between the soils of bare patches and soils of the rhizosphere regions of selected plants. (4) Lateral differences in NO3--N and exchangeable NH4+-N concentrations were significant (P < 0.01) and probably resulted from the N utilization patterns and soil microclimates differing beneath the species studied. (5) Significant seasonal changes in total N, NO3--N and NH4+-N were apparent in the soils. (6) Direct effects of fire were evidenced by the increased total N (input of 66 kg N ha-1) and exchangeable NH4+-N concentrations found at the soil surface immediately after a fire. The flush of available NH4+-N was of short duration. (7) The indirect effects of fire on soil N observed in the year following the fire were increased total N concentrations down the profile and increased concentrations of NO3--N which lasted nine months. (8) Fire is apparently an effective mineralizing agent in soils of the coastal fynbos and has substantial effects on the concentration, form and distribution of the low nitrogen reserves. [ABSTRACT FROM AUTHOR]

Drought adversely affects vegetation conditions and agricultural production and consequently the food security and livelihood situation of the often most vulnerable communities. In spite of recent advances in modeling drought risk and impact, coherent and explicit information on drought hazard, vulnerability and risk is still lacking over wider areas. In this study, a spatially explicit drought hazard, vulnerability, and risk modeling framework was investigated for agricultural land, grassland and shrubland areas. The developed drought hazard model operates on a higher spatial resolution than most available drought models while also being scalable to other regions. Initially, a logistic regression model was developed to predict drought hazard for rangelands and croplands in the USA. The drought hazard model was cross-verified for the USA using the United States Drought Monitor (USDM). The comparison of the model with the USDM showed a good spatiotemporal agreement, using visual interpretation. Subsequently, the explicit and accurate USA model was transferred and calibrated for South Africa and Zimbabwe, where drought vulnerability and drought risk were assessed in combination with drought hazard. The drought hazard model used time series crop yields data from the Food and Agriculture Organization Corporate Statistical Database (FAOSTAT) and biophysical predictors from satellite remote sensing (SPI, NDVI, NDII, LST, albedo). A McFadden's Pseudo R² value of 0.17 for the South African model indicated a good model fit. The plausibility of the drought hazard model results in southern Africa was evaluated by using regional climate patterns, published drought reports and a visual comparison to a global drought risk model and food security classification data. Drought risk and vulnerability were assessed for southern Africa and could also be spatially explicit mapped showing, for example, lower drought vulnerability and risk over irrigated areas. The innovative aspect of the presented drought hazard model is that it can be applied to other countries at a global scale, since it only uses globally available data sets and therefore can be easily modified to account for country-specific characteristics. At the same time, it can capture regional drought conditions through a higher resolution than other existing global drought hazard models. This model addressed the gap between global drought models, that cannot spatially and temporally explicitly capture regional drought effects, and sub-regional drought models that may be spatially explicit but not spatially transferable. Since we used globally available and spatially consistent data sets (both as predictors and response variables), the approach of this study can potentially be used globally to enhance existing modelling routines, drought intervention strategies and preparedness measures. [ABSTRACT FROM AUTHOR]

Many studies have investigated the water relations of indigenous plants in the fynbos shrublands of the Cape, South Africa. These have mainly focused on understanding the mechanisms by which individual plant species respond to droughts, the frequency and severity of which is expected to increase due to climate change. However, comparatively little information exists on the dynamics of water use by indigenous plants in the region, and, in particular, how water use varies seasonally and between sites. In this study we determined water use by 3 fynbos vegetation types growing at 4 different sites, namely: (i) lowland Atlantis Sand Plain fynbos growing on deep sandy soils, (ii) Kogelberg Sandstone fynbos growing in a riparian zone on deep alluvial soils, (iii) dryland Kogelberg Sandstone fynbos growing on shallow sandy soils at a montane site, and (iv) alluvial Swartland fynbos growing in clayey soils. Evapotranspiration (ET) was quantified at each site during specific periods using a boundary layer scintillometer and energy balance system. A simple dual source model in which the stand ET was calculated as the algebraic sum of outputs from soil evaporation and transpiration sub-models was used to scale up the ET measurements to annual values. The data showed large differences in ET depending on site characteristics and on plant attributes. Dense stands of riparian Sandstone Fynbos had an annual ET of 1 460 mm which exceeded the reference ET of 1 346 mm. Dryland Sandstone Fynbos used only 551 mm of water per year while the Sand Plain Fynbos' annual ET was 1 031 mm, which was similar to the reference ET of 1 059 mm. We conclude that some indigenous plant species use large volumes of water which should be accounted for in, e.g., groundwater recharge estimates, and calculations of incremental water gains after clearing alien invasive plants, among other applications. [ABSTRACT FROM AUTHOR]

Quantification of the water cycle components is key to managing water resources. Remote sensing techniques and products have recently been developed for the estimation of water balance variables. The objective of this study was to test the reliability of LandSAF (Land Surface Analyses Satellite Applications Facility) evapotranspiration (ET) and SPOT-Vegetation Normalised Difference Water Index (NDWI) by comparison with ground-based measurements. Evapotranspiration (both daily and 30 min) was successfully estimated with LandSAF products in a flat area dominated by fynbos vegetation (Riverlands, Western Cape) that was representative of the satellite image pixel at 3 km resolution. Correlation coefficients were 0.85 and 0.91 and linear regressions produced R2 of 0.72 and 0.75 for 30 min and daily ET, respectively. Ground-measurements of soil water content taken with capacitance sensors at 3 depths were related to NDWI obtained from 10-daily maximum value composites of SPOT-Vegetation images at a resolution of 1 km. Multiple regression models showed that NDWI relates well to soil water content after accounting for precipitation (adjusted R2 were 0.71, 0.59 and 0.54 for 10, 40 and 80 cm soil depth, respectively). Changes in NDWI trends in different land covers were detected in 14-year time series using the breaks for additive seasonal and trend (BFAST) methodology. Appropriate usage, awareness of limitations and correct interpretation of remote sensing data can facilitate water management and planning operations. [ABSTRACT FROM AUTHOR]