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Native grasslands have been vastly transformed with the expansion of human activities. Applied fire regimes offer conservation-based management an opportunity to enhance remaining grassland biodiversity and secure its persistence into the future. Fire regimes have complex interactions with abiotic and biotic ecosystem components that influence environmental heterogeneity and biodiversity. We examined the pyrodiversity–biodiversity hypothesis, which suggests that more species are supported where pyrodiversity, that is, the level of environmental heterogeneity associated with different fire regimes, is greater. A mesocosm-type field experiment, maintained for 38 yr, was used to determine the response of plant diversity to 1-, 2-, 5- and 12-yr fire-return interval treatments, with early-dormant, middormant and early–growing season burns. Our sampling regime was designed to assess the influence of fire treatments and combinations thereof, over spatial scale, on plant diversity. Pyrodiversity was maximized where fire regime diversity, simulated by varying the size of patches with different fire treatments, was greatest. Species richness was predicted to be reduced at short and long extremes of fire-return interval, as suggested by the intermediate-disturbance hypothesis. The influence of fire treatments on alpha and beta diversity, and plant functional groups, were tested using multivariate and Bayesian models. Multilevel models of plant height and growth form, with fire-return interval, reflected the strong indirect influence of fire-return interval on sward structure and the plant environment. The pyrodiversity–biodiversity and intermediate-disturbance hypotheses were only partially supported and depended on the plant group and spatial scale of assessment. Although both frequent and infrequent burns made important contributions to overall species richness, richness peaked where 20–40% of the area was protected from frequent fires. The larger contribution of frequent burning to diversity was due to an interaction with scale and forb turnover over the trial area. Extremes in fire-return intervals reduced forb richness, supporting the predictions of the intermediate-disturbance hypothesis. Spring burns had a weak negative influence on forb alpha diversity, but only at small scales. For a meaningful contribution of management to plant diversity, traditional fixed biennial burns need to be supplemented with smaller patches burned with longer fire-return intervals, and extremes in fire-return intervals avoided.

African elephants can convert woodland to shrubland or grassland. Moderate conversion observed at low elephant densities may improve conditions for other animals, while extensive transformation at high densities may reduce plant and animal diversity. The threshold density separating facilitation from habitat destruction varies spatially and is partly determined by food choice, which differs between adult bulls and members of breeding herds. When elephants consume herbaceous forage, woodland damage is low but this increases when woody plants are the primary food source. Consequently, an understanding of diet selection by elephants is important for forecasting the degree of vegetation conversion. One hypothesis is that elephants select forage that provides the highest rate of intake. The mass harvested per trunkload is a constraint to intake and therefore this study sought to determine if trunkload mass changes seasonally; varies across common forage types utilised by elephants; and differs between adult bulls and members of breeding herds. Mechanistic models were used to estimate the mass harvested per trunkload of green grass, mixed green and dry grass, forbs, and leaves and bark from woody plants across a heterogenous, semi-arid savanna at a daily time step for one annual cycle. Separate models were constructed for adult bulls and members of breeding herds. Harvestable mass changed seasonally for herbaceous forage and for leaves from woody plants but was constant for canopy bark. The maximum average trunkload mass of green grass was >75 times heavier than the bite mass reported for other grazers while trunkloads of leaves from woody plants were only eight times heavier than the bite mass reported for other browsers. This is attributed to the advantage provided by the trunk, which increases harvestable mass beyond the constraint of mouth volume, particularly when feeding on grass. Herbaceous forage yielded heavier trunkloads than leaves and bark from woody plants during the wet season, but this was reversed in the dry season. Adult bulls harvested heavier trunkloads than members of breeding herds for all forage types except forbs; and adult bulls harvested disproportionately large trunkloads of grass and bark. The strong correlation between the model outputs and well-established trends in the seasonal changes in elephants' diet suggests that elephants are preferential foragers of the largest trunkload on offer. Consequently, they are grazers when suitable herbaceous forage is available, and browsers when it is scarce. Green grass provides adult bulls with disproportionately large trunkloads and, therefore, adult bulls are predicted to have a strong preference for green grass. Availability of suitable green grass during the dry season may therefore buffer woodlands from heavy impact by adult bulls. Consequently, where possible, protected areas with elephants should aim to include key grass resources.

Land-cover change and habitat loss are widely recognised as the major drivers of biodiversity loss in the world. Land-cover maps derived from satellite imagery provide useful tools for monitoring land-use and land-cover change. KwaZulu-Natal, a populous yet biodiversity-rich province in South Africa, is one of the first provinces to produce a set of three directly comparable land-cover maps (2005, 2008 and 2011). These maps were used to investigate systematic land-cover changes occurring in the province with a focus on biodiversity conservation. The Intensity Analysis framework was used for the analysis as this quantitative hierarchical method addresses shortcomings of other established land-cover change analyses. In only 6 years (2005-2011), a massive 7.6% of the natural habitat of the province was lost to anthropogenic transformation of the landscape. The major drivers of habitat loss were agriculture, timber plantations, the built environment, dams and mines. Categorical swapping formed a significant part of landscape change, including a return from anthropogenic categories to secondary vegetation, which we suggest should be tracked in analyses. Longer-term rates of habitat loss were determined using additional land-cover maps (1994, 2000). An average of 1.2% of the natural landscape has been transformed per annum since 1994. Apart from the direct loss of natural habitat, the anthropogenically transformed land covers all pose additional negative impacts for biodiversity remaining in these or surrounding areas. A target of no more than 50% of habitat loss should be adopted to adequately conserve biodiversity in the province. Our analysis provides the first provincial assessment of the rate of loss of natural habitat and may be used to fulfil incomplete criteria used in the identification of Threatened Terrestrial Ecosystems, and to report on the Convention on Biological Diversity targets on rates of natural habitat loss.

Accurately detecting the magnitude and direction of population trends provides essential information for conservation management. There are numerous local and international long-term waterbird monitoring programmes with substantial variation in how frequently surveys are conducted. We aimed to assess how temporal frequency of waterbird surveys influence three aspects of population trends: (1) level of uncertainty around estimates of long-term trends; (2) frequency, duration and overlap of significant short-term increases or declines in trend trajectory; and (3) differences between estimated change in population size measured over four different time periods. Data from 28 years of surveys at a waste water treatment facility in South Africa were used to model the population trend of 41 waterbird species. We used generalised additive mixed-models to compare significance and magnitude of population change trends between monthly and biannual surveys. Direction and shape of species trends were similar between protocols although uncertainty around trends was generally lower when monthly data were used. The number of significant trend trajectories, the majority of which were declines, was higher in monthly models. Temporal overlap of periods of significant change of trends of the two protocols averaged 30%. However, both sampling protocols offered similar conclusions about long-term change in population size of species. General patterns differed conspicuously among species, although groups of species showed similar trajectories of population change. We conclude that biannual surveys are appropriate if the goal is to assess general patterns of population change. However, if management action relies on understanding the significance of population trajectories, surveys at a finer temporal scale are required, especially for species showing a pattern of unpredictable movement. Trade-offs between logistical constraints and statistical rigour as well as species identity need to be carefully considered for the design of long-term monitoring programmes of waterbirds.

Background: Inselberg summits adjacent to the Maloti–Drakensberg escarpment occupy an alpine zone within the Drakensberg Alpine Centre (DAC). Inselbergs, the escarpment and surrounding mountains such as Platberg experience a severe climate; inselberg summits are distinct by being protected from human disturbance. Objectives: The aim of this article was to describe for the first time the flora of inselberg summits and to assess their potential contribution to conservation of DAC plant diversity. Method: We investigated whether the flora of inselberg summits formed a representative subset of the DAC flora in terms of shared, especially endemic or near endemic, species and representation of families. All species were listed for six inselbergs between Giant’s Castle and Sentinel, located in the Royal Natal National Park (RNNP) during November 2005. Comparisons, using literature, were made with floras of the DAC, as well as Platberg, an inselberg approximately 60 km north from Sentinel in the RNNP. Results: We recorded 200 species of pteridophytes and angiosperms on inselbergs, 114 DAC endemics or near endemics, one possible new species, and several range and altitudinal extensions. Asteraceae, Poaceae and Ericaceae comprised 42.1% of endemic and near endemic species, with Scrophulariaceae and Hyacinthaceae contributing 8.8%. Inselberg and DAC floras differed in respective rankings of Crassulaceae (8th vs. > 15th), Polygalaceae, Apiaceae and Rosaceae (10th, 11th, 12th vs. > 15th), Poaceae (2nd vs. 5th), Cyperaceae (3rd vs. 4th) and Scrophulariaceae (6th vs. 2nd). Growth forms on inselbergs were consistent with DAC flora. Inselbergs shared 40% of species with Platberg. Conclusion: Inselbergs, which supported 7.9% of species occurring in the DAC flora, are well protected from human impact, lack alien plants, but, despite this, are highly vulnerable to climate change. Conservation importance of inselbergs will increase as escarpment vegetation becomes increasingly degraded as a consequence of intensifying land use.

Loss of biodiversity caused by impact of elephants (Loxodonta africana) on African woodlands may require a management response, but any action should be based on an understanding of why elephants choose to utilise trees destructively. Comprehension of elephant feeding behaviour requires consideration of the relative value of the plant groups they may potentially consume. Profitability of available food is partly determined by the time to locate a food patch and, therefore, as a foundation for understanding the influence of food availability on diet selection, key controls on the density of grass, forb, and browse patches were investigated across space and time in a semi-arid African savanna. Density of food patches changed seasonally because plant life-forms required different volumes of soil water to produce green forage; and woody plants and forbs responded to long-term changes in soil moisture, while grasses responded to short-term moisture pulses. Soil texture, structure of woody vegetation and fire added further complexity by altering the soil water thresholds required for production of green forage. Interpolating between regularly-timed, ground-based measurements of food density by using modelled soil water as the predictor in regression equations may be a feasible method of quantifying food available to elephants in complex savanna environments.

Invertebrate herbivore outbreaks have important impacts on system biogeochemical cycling, but these effects have been poorly documented in African savanna ecosystems. In semi-arid African savannas, outbreaks of the lepidopteran Imbrasia belina (mopane worm) affect discrete patches of the dominant Colophospermum mopane trees; larvae may completely defoliate trees for up to six weeks during each of the early and late growing seasons. We studied the impact of mopane worm outbreaks on the availability of nitrogen (N), phosphorus (P), and potassium (K) within mopane savanna by quantifying major nutrient pools in defoliated and non-defoliated savanna patches, including leaves, leaf litter, worm frass, and the soil beneath trees. Within an outbreak area, approximately 44 percent of trees were infested, supporting ~29,000 worms/ha, leading to ~640 kg/ha dry weight frass deposition at 1.4 g of frass/day-individual (fourth or fifth instar), compared with an average 1645 kg/ha dry weight of leaf on trees most of which should be deposited by litterfall at the end of the growing season. Frass had twofold higher P, 10 percent higher K, but equivalent N content than litter. Taking frass and litter deposition together, the N, P, and K contents added due to the outbreak event at our study site were 0.88, 5.8, and 2.8 times those measured in non-outbreak patches, a pattern which was reflected in the nutrient contents of soil surfaces beneath defoliated trees. Invertebrate herbivory appears to be an important driver for mopane savanna but has been largely neglected.

As a foundation for understanding the diet of African savanna elephants ( Loxodonta africana ), adult bulls and cows were observed over an annual cycle to determine whether harvesting ( P t ), chewing ( C t ) and handling times ( H t ) differed across food types and harvesting methods (handling time is defined as the time to harvest, chew and swallow a trunkload of food). Bulls and cows were observed 105 and 26 times, respectively (94 and 26 individuals), with a total of 64 h of feeding recorded across 32 vegetation types. Some food types took longer to harvest and chew than others, which may influence intake rate and affect choice of diet. The method used to gather a trunkload of food had a significant effect on harvesting time, with simple foraging actions being comparatively rapid and more difficult tasks taking longer. Handling time was constrained by chewing for bulls, except for the processing of roots from woody plants, which was limited by harvesting. Time to gather a trunkload had a greater influence on handling time for cows compared to bulls. Harvesting and handling times were longer for bulls than cows, with the sexes adopting foraging behaviors that best suited their energy requirements.

Habitat loss and climate change are primary drivers of global biodiversity loss. Species will need to track changing environmental conditions through fragmented and transformed landscapes such as KwaZulu-Natal, South Africa. Landscape connectivity is an important tool for maintaining resilience to global change. We develop a coarse-grained connectivity map between protected areas to aid decision-making for implementing corridors to maintain floristic diversity in the face of global change. The spatial location of corridors was prioritised using a biological underpinning of floristic composition that incorporated high beta diversity regions, important plant areas, climate refugia, and aligned to major climatic gradients driving floristic pattern. We used Linkage Mapper to develop the connectivity network. The resistance layer was based on land-cover categories with natural areas discounted according to their contribution towards meeting the biological objectives. Three corridor maps were developed; a conservative option for meeting minimum corridor requirements, an optimal option for meeting a target amount of 50% of the landscape and an option including linkages in highly transformed areas. The importance of various protected areas and critical linkages in maintaining landscape connectivity are discussed, disconnected protected areas and pinch points identified where the loss of small areas could compromise landscape connectivity. This framework is suggested as a way to conserve floristic diversity into the future and is recommended as an approach for other global connectivity initiatives. A lack of implementation of corridors will lead to further habitat loss and fragmentation, resulting in further risk to plant diversity.

Collective properties of biodiversity, such as beta diversity, are suggested as complementary measures of species richness to guide the prioritisation and selection of important biodiversity areas in regional conservation planning. We assessed variation in the rate of plant species turnover along and between environmental gradients in KwaZulu-Natal, South Africa using generalised dissimilarity modelling, in order to map landscape levels of floristic beta diversity. Our dataset consisted of 434 plots (1000 m 2 ) containing 997 grassland and savanna matrix species. Our model explained 79 % of the null deviance observed in floristic dissimilarities. Variable rates of turnover existed along the major environmental gradients of mean annual temperature, median rainfall in February, and soil cation exchange capacity, as well as along gradients of geographical distance. Beta diversity was highest in relatively warm, drier summer regions and on dystrophic soils. Areas of high beta diversity identify areas that should be included in conservation plans to maximise representation of diversity and highlight areas best suited to protected area expansion. Biome transition areas in high beta diversity areas may be susceptible to climate variability. Including beta diversity turnover rates in regional conservation plans will help to preserve evolutionary and ecological processes that create and maintain diversity.