Scielo RSS <![CDATA[Koedoe]]> http://www.scielo.org.za/rss.php?pid=0075-645820200002&lang=en vol. 62 num. 2 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Connections between abiotic and biotic components of a granite catena ecosystem in Kruger National Park</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200001&lng=en&nrm=iso&tlng=en <![CDATA[<b>Biotic and abiotic connections on a granitic catena: Framework for multidisciplinary research</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200002&lng=en&nrm=iso&tlng=en Local environmental gradients on a catenal scale create ecological patterns from the crest to the stream of the hillslope. Bottom-up drivers interact with top-down controls to give rise to these patterns. A multidisciplinary project was conducted to study the processes that govern functioning, structure and heterogeneity on a catena in a third-order catchment in the Southern Granite Supersite in the Kruger National Park. The project included abiotic components (e.g. groundwater-surface water interactions, soil chemical and physical properties) as well as biotic components (e.g. soil microbes, small aquatic organisms in ephemeral pools, plant communities, vegetation structure and mammal diversity). Each of these components was investigated in detail along the catenal gradient and reported on in separate articles in this special issue. The drought of 2015-2016 occurred during the sampling period of the study and information on the response of vegetation and mammals to the drought were included. In this article, a synthesis of findings from the separate components or disciplines is provided to highlight the interactive functioning and ecological patterns of the catena. These findings were then used to develop a framework for multidisciplinary studies in similar environments. The framework highlights the interactive relationships between various components of the ecosystem and the importance of a multidisciplinary approach.CONSERVATION IMPLICATIONS: The findings of this study were used to develop a conceptual framework outlining how a range of biotic and abiotic patterns and processes interact along the catenal gradient. The framework highlights the importance of recognising these interactions in a multidisciplinary approach focused on one supersite <![CDATA[<b>Identification of hydropedological flowpaths in Stevenson-Hamilton catena from soil morphological, chemical and hydraulic properties</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200003&lng=en&nrm=iso&tlng=en In highly variable water regimes of semi-arid savannahs, water is the key driving force for biotic and abiotic processes. Understanding and measuring components of the hydrological cycle at landscape scale is however difficult because of the spatiotemporal variation of these processes. Hydropedology is a new interdisciplinary research field aiming to use soil information to conceptualise hydrological processes at different scales. In this study, a hydropedological approach was used to identify key hydrological flowpaths on a granitic catena in the Stevenson-Hamilton Supersite in the Kruger National Park. Soils from 49 plots, spaced 10 m apart along a catena, were classified, and their morphology was interpreted in relation to the dominant hydrological response. Soil samples were taken at 10-cm-depth intervals for chemical and physical analysis to assess the relationship between their expected hydrological behaviour and physiochemical properties. The hydropedological survey indicated that the crest is dominated by freely drained recharge soils where infiltration and vertical drainage are dominant. On the midslope, the underlying bedrock has restricted permeability; this promotes lateral flow at the soil/bedrock interface. On the upper footslope, high clay content soils (sodic) restricts further lateral drainage, resulting in return flow (seepage). Overland flow is dominant on the upper and lower footslope. The valley bottom is occupied by freely drained alluvial soils, which act as a recharge zone. The chemical and physical analyses of soil support the interpretations of the hydropedological interpretation of the soil morphology.CONSERVATION IMPLICATIONS: Understanding hydrological processes is important for sustainable water resource management, especially in the areas with highly variable water regimes. A hydropedological approach provides an efficient method to characterise dominant flowpaths at landscape scale. This aids the estimation of the hydrological sensitivity of the landscape to climate and land use changes <![CDATA[<b>Groundwater-surface water interactions in an ephemeral savanna catchment, Kruger National Park</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200004&lng=en&nrm=iso&tlng=en The semi-arid conditions in savanna landscapes ensure that ephemeral drainage dominates the hydrological network in these dryland systems. Quantification of their hydrological processes is important to inform ecosystem understanding and future conservation efforts under a changing climate, and to provide guidance for restoration. By combining in situ hydrometric observations, hydrochemistry, remote sensing and a soil water balance model, we characterise the groundwater-surface water interactions in ephemeral low-order catchments of the granitoid regions of the southern Kruger National Park (KNP). Streams at the lowest orders are augmented by lateral interflows from the catena, although the second- and third-order stream reaches are conduits for groundwater recharge to the fractured rock aquifer; the soils of the crests and foot-slopes also show preferential flow, and are truly recharge soils, whilst the duplex soils of the midslopes clearly show their responsive nature to a low soil moisture deficit in the shallow horizons. Actual evaporation (aET) differed between catena elements with surprisingly little variation at third-order hillslopes, with the greatest overall aET at the first order. Meanwhile, soil water balances demonstrated a significant variation in storage of the riparian zones as a result of interflow from upslope and aET losses. Furthermore, data support broader-scale observations that groundwater recharge through the vadose zone to the fractured rock aquifer is dependent upon threshold antecedent precipitation conditions. Moderate precipitation events (5 mm/day - 35 mm/day) over a 2-3 week period initiate groundwater responses with a 2-3 month lag, whilst intense precipitation events (>100 mm/day) are expressed within 2-3 weeks.CONSERVATION IMPLICATIONS: Understanding the lateral connectivity of terrestrial ecosystems to the ephemeral drainage network expressed via hydrological processes in these savanna landscapes is important to infer potential impacts of climate variability on the continued conservation of these ecosystems, both within and external to protected areas <![CDATA[<b>Hydrological response in a savanna hillslope under different rainfall regimes</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200005&lng=en&nrm=iso&tlng=en Soil water is a link between precipitation and the functioning of ecological systems. It is therefore critical to understand exactly how soil water regimes are affected by changes in precipitation. This is especially true for the variable water regimes of savanna ecosystems. Therefore, understanding the effects of precipitation on soil water was the central goal of this article. The hydropedological behaviour of a catena in the Stevenson Hamilton Research Supersite of the Kruger National Park was configured as a conceptual model of catchment modelling framework, a toolbox of various model structures and processes. The model was parameterised using measured hydraulic properties of the soils, and calibrated and validated using measured soil matric potentials and derived actual evapotranspiration (aET) data. The model was then used to simulate hydrological response under five different rainfall scenarios, ranging from 30% drier than the normal rainfall to 30% wetter than the normal rainfall. The scenarios also included rainfall years with fewer but larger rain events, that is, more intense rainfall events. In general, the model performed well with Pearson's correlation coefficient (R) values ranging between 0.66 and 0.87 and between 0.58 and 0.69 for correlations with daily soil matric potential and daily aET, respectively. Scenario analysis indicates non-linearity in the response of hydrological processes to changes in precipitation. This is especially evident in a seven-fold increase in the duration of saturation at the seepage surface associated with a 30% increase in rainfall. In general, the impact of drying conditions (30% below average rain) has a greater influence on soil water contents, overland flow and percolation from the riparian zone to bedrock than a 30% increase in rainfall would have on the same process.CONSERVATION IMPLICATIONS: This article presents realistic predictions of the potential impact of changes in precipitation on hydrological processes in an important area of the Kruger National Park. These predictions would enable decision-makers to be prepared for the anticipated changes in near-surface hydrological processes associated with climate changes <![CDATA[<b>The rhizobiome of herbaceous plants in Clovelly and Sterkspruit soils of the Stevenson-Hamilton supersite</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200006&lng=en&nrm=iso&tlng=en By attracting microorganisms from the surrounding soil via root exudates, the composition of microbial populations in the rhizosphere of plants is regulated and maintained according to the genotype of the plant and its abiotic soil environment. This project investigated the bacterial diversity of the rhizosphere microbiome (i.e. rhizobiome) of the three most common herbaceous plants (Kyphocarpa angustifolia [Amaranthaceae, Caryophyllales], Melhania acuminata [Malvaceae, Malvales] and Sida cordifolia [Malvacae, Malvales]) growing mutually in two different soil types (Clovelly [top] and Sterkspruit [bottom]) with differing abiotic characteristics at a granite catenal supersite in the Kruger National Park, South Africa. Two plant species (K. angustifolia and S. cordifolia) occurred at both the top and bottom sites, whilst M. acuminata only occurred at the top site. Ten rhizosphere samples were collected per plant from both the top and bottom sites, comprising a total of 50 samples. Biolog EcoPlates™ were used to assess differences in carbon source utilisation patterns by bacteria in the rhizobiome. For next-generation sequencing analysis, the DNA from four randomly selected rhizosphere soil samples from each plant species, at both the top and bottom sites, was combined to yield two samples from each locality for each species. Targeted metagenomic sequencing of the 16S rRNA gene region (V3 and V4 regions) was used to characterise the rhizobiome. Actinobacteria and Proteobacteria were the most dominant phyla in all rhizobiomes, and unique and shared operational taxonomic units were identified in all the rhizobiomes. Principal component analysis of the Biolog data revealed no disparity between the five rhizobiomes.CONSERVATION IMPLICATIONS: The results obtained in this study could play a role in micro-ecological scale conservation and management because microbial diversity in soils plays a vital role in shaping above-ground biodiversity and terrestrial ecosystem dynamics <![CDATA[<b>Fungal community structure variability between the root rhizosphere and endosphere in a granite catena system in Kruger National Park, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200007&lng=en&nrm=iso&tlng=en Fungi colonise various substrates such as organic matter (dead or alive) from plants or animals. These fungi can be specialists (i.e. belonging to a substrate) or generalists (i.e. surviving on different types of organisms). Fungi fulfil various functions in specialised niches, for example, acting as plant pathogens, helping in plant growth from the root systems or decomposing organic matter and fertilising soil. Species are specialised to occur in only one niche, or others can utilise or occur in various niches. For example, certain species occur only within certain plant tissues (endophytes), on the exterior surface of the plants growing above the ground (epiphytes) or below the ground in the sphere surrounding the roots (rhizosphere). Different soil types or conditions can favour certain species. This study used environmental sequencing to characterise the fungal communities associated with the root exterior and interior of Sida cordifolia, a plant growing across the varying soil conditions of the catena system. Fungal rhizosphere communities between three commonly occurring plant species - S. cordifolia, Melhania acuminata (both Malvaceae) and Kyphocarpa angustifolia (Amaranthaceae) - in one of the soil types were also studied to compare and contrast the fungal rhizosphere communities of these herbs. Molecular Operational Taxonomic Units co-occurred between niches, soil conditions and the rhizospheres of three plants at the same location, whilst others were restricted to only one niche or plant species. Results showed that soil conditions in a catena can influence the associations of fungal species between different catena zones, on the outside and inside of the roots, and that these communities also differ between plant species.CONSERVATION IMPLICATIONS: This study showed that complex and sensitive fungal communities are associated with plant roots in different zones of the catena. This is most likely also true between different habitats and soil types on a larger scale. This study emphasises the need to also manage a catena system on the micro-ecological scale whilst framing conservation and management plans of the Kruger National Park <![CDATA[<b>Vegetation distribution along a granite catena, southern Kruger National Park, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200008&lng=en&nrm=iso&tlng=en This study aimed to investigate how environmental factors drive the assemblage of vegetation within a landscape at various scales, particularly to which extent a sequence of soil forms (catena) influences plant community distribution in a savanna of Kruger National Park, South Africa. On a regional scale, the geology and associated soil forms correspond to the Granite Lowveld Vegetation Type. These associations were studied at the scale of a single hillslope, comprising concurrent soil and vegetation surveys from the crest to footslopes. From chemical and physical soil analyses, strong correlations between the distribution of soil moisture content, soil forms and plant species at community, sub-community and variant levels were found. A Vachellia exuvialis-Pogonarthria squarrosa-dominated savanna is restricted to the well-drained, nutrient-poor, acidic and sandy soils of the crests and upper-midslopes of the granite domes. On sodic sites along lower-midslopes, Dactyloctenium aegyptium-Sporobolus nitens grasslands dominate the clay-rich soils. The footslopes are characterised by the grass Themeda triandra and the shrub Flueggea virosa. The grass Panicum maximum growing under tall trees such as Diospyros mespiliformis and Spirostachys africana typifies riparian vegetation along seasonal streams on deep alluvial soil. The association between plant communities and soil forms exemplifies the interdependency of biotic and abiotic components that maintain heterogeneity within the ecosystem from biome to community scale.CONSERVATION IMPLICATIONS: This article contributes to understanding plant species distribution along a granite catena; an integral part of which are sodic sites that become overutilized by game, which, albeit natural, could severely impact these sites during drought situations <![CDATA[<b>Vegetation structure and spatial heterogeneity in the Granite Supersite, Kruger National Park</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200009&lng=en&nrm=iso&tlng=en Spatial heterogeneity is the unequal distribution of landscape features and consists of diversity in vegetation structure, number and size of woody plants, patchiness in grass cover, sub-canopy habitats, etc. A granite catena (hillslope) comprises of a gradient of soils, hydrology patterns and vegetation composition, creating a spatially heterogeneous area with variety in animal habitats. Objectives were to determine small-scale spatial heterogeneity along a catena near Skukuza, such as vegetation structure, patchiness, size and cover of woody and grass components, to describe certain catenal processes. Tree sizes and canopy cover were measured and the point method used on seven 100 m transects representing different catenal zones. Grasses were categorised according to grazing value, ecological status and percentage shade tolerant grasses. A total of 155 tree canopies were present. Large trees (&gt; 5 m) occurred in riparian zone and upper midslope, but were low in number (< 4 per transect). Woody plants ranged in number from 8 to 32, canopy cover 4.5% - 33.6%, and grass cover from 47% to 69% between zones. A strong correlation was found between canopy cover and shade-tolerant grasses. Size of sub-canopy habitats are mostly determined by size of woody plants and both are important to animals. Various factors related to vegetation contributed to heterogeneity and spatial stratification patterns of the catena ecosystem.CONSERVATION IMPLICATIONS: Concerns about the decline in tree numbers inside Kruger National Park are addressed. Mammal habitats and plant communities are impacted by the decline. The research can be linked to the long-term exclosure studies on granites at Nkuhlu <![CDATA[<b>Plant community structure and possible vegetation changes after drought on a granite catena in the Kruger National Park, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200010&lng=en&nrm=iso&tlng=en A preliminary study investigated the associations between vegetation communities along catenary soil gradients in 2015. The severe drought of 2016 in South Africa presented the opportunity to study post-drought savanna vegetation changes. This hillslope transect was surveyed for five successive seasons. The Braun-Blanquet method was used, and the data were analysed by means of the TWINSPAN algorithm, which resulted in the classification of different communities on the crest, sodic site and riparian area. Change in herbaceous and grassy vegetation composition and diversity in the transect is compared between rainfall years, wet and dry seasons, and three different zones (crest, sodic site and riparian areas). Spatial and temporal autocorrelation of the woody component shifted the focus to variance within the graminoid and herbaceous layers. Clear vegetation changes were observed on the crest and the sodic sites, whereas changes in the riparian area were less obvious. In all three habitats, species richness decreased after the drought and did not reach pre-drought levels even after two years. However, plant species diversity was maintained as climax species were replaced by pioneer and sub-climax species. These changes in community structure, which had reverted to systems dominated by climax species by the end of the sampling period, might be an indication of the savanna ecosystem's resilience to drought conditions.CONSERVATION IMPLICATIONS: Although clear vegetation changes were observed in the five successive seasons after the drought, this study showed that the savanna ecosystem is relatively resistant to drought and that human intervention is not needed <![CDATA[<b>Variation in mammal diversity and habitat affect heterogeneity and processes of a granite catena</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200011&lng=en&nrm=iso&tlng=en A higher variety of habitats normally result in higher diversity of species. The granite catenas near Skukuza, Kruger National Park (KNP), consist of different soil types along the hillslope, creating different habitats. Objectives were to determine the mammal species present on a catena and surrounding areas; to indicate their main period of activity; and to indicate human visibility in each catenal zone to explain landscape of fear principles. Camera trap surveys were conducted for short periods and repeated over three years. In total, 31 mammal species were observed on the catena, and its nearest waterholes. Small to mega-sized mammals were present, but some species were only observed during one survey period. Small changes were noticed in activity periods between survey periods, probably due to the drought. A severe drought changed vegetation structure and visibility, but the study area appeared to act as a drought forage refuge. The lowest visibility was found at the sodic patch upper-midslope ecotone, and shrub veld. This can possibly explain the lower number of mammal observations in these areas. Different habitats and habitat features were described which can affect the presence of mammals, i.e. the mud wallows that were created and maintained by the mammals. Future studies can focus on the impact of seasonal changes in mammal presence and on mammal diversity during a normal rainfall year.CONSERVATION IMPLICATIONS: To understand the mechanisms of herbivores as ecosystem drivers, aspects such as vegetation, soil and mammals should be combined. Better understanding of mammals, their habitats and associated processes can lead to better conservation actions <![CDATA[<b>First report of various <i>Fusarium</i> species from the Stevenson-Hamilton Supersite granite catena system in the Kruger National Park, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200012&lng=en&nrm=iso&tlng=en A higher variety of habitats normally result in higher diversity of species. The granite catenas near Skukuza, Kruger National Park (KNP), consist of different soil types along the hillslope, creating different habitats. Objectives were to determine the mammal species present on a catena and surrounding areas; to indicate their main period of activity; and to indicate human visibility in each catenal zone to explain landscape of fear principles. Camera trap surveys were conducted for short periods and repeated over three years. In total, 31 mammal species were observed on the catena, and its nearest waterholes. Small to mega-sized mammals were present, but some species were only observed during one survey period. Small changes were noticed in activity periods between survey periods, probably due to the drought. A severe drought changed vegetation structure and visibility, but the study area appeared to act as a drought forage refuge. The lowest visibility was found at the sodic patch upper-midslope ecotone, and shrub veld. This can possibly explain the lower number of mammal observations in these areas. Different habitats and habitat features were described which can affect the presence of mammals, i.e. the mud wallows that were created and maintained by the mammals. Future studies can focus on the impact of seasonal changes in mammal presence and on mammal diversity during a normal rainfall year.CONSERVATION IMPLICATIONS: To understand the mechanisms of herbivores as ecosystem drivers, aspects such as vegetation, soil and mammals should be combined. Better understanding of mammals, their habitats and associated processes can lead to better conservation actions <![CDATA[<b>Integrating multi-scaled and multidisciplinary studies: A critical reflection on the Kruger National Park research supersites</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200013&lng=en&nrm=iso&tlng=en The Kruger National Park (KNP) research supersites were designed to encourage place-based research in order to geographically focus research activities on known and well described study sites as opposed to ad hoc site selection practiced previously. This was done by (i) delineating sites using a clear rationale, (ii) providing basic meta-data for these sites, and (iii) actively encouraging scientists to conduct research on these sites and share data freely. The underlying concept was that geographically focused research would facilitate data and knowledge exchanges and lead to long-term, multi-scaled and cross-disciplinary studies at these data-rich sites, facilitating an integrated and collectively developed understanding that would be hard to achieve otherwise. This essay acts as a short-term reflection on the KNP supersites and an introductory text for the special issue focusing on the outcomes from a multi-disciplinary study conducted on the southern granitic supersite. It starts off by briefly introducing the supersite concept, followed by a reflection on the achievements and challenges towards achieving the main objectives of the supersites. In addition, and as part of the "data-begets-data" philosophy underlying the supersites (i.e positive feedback of place-based data attracting further research and hence collection of further data), updated lists of references and available datasets are provided.CONSERVATION IMPLICATIONS: This paper highlights the successes and challenges of geographically focusing research in the KNP to the research supersites in order to facilitate integrative and multi-scaled learning in savanna systems. It also provides updated lists of references and available datasets to further stimulate research at these sites <![CDATA[<b>A tribute to Frederick (Fred) J. Kruger</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200014&lng=en&nrm=iso&tlng=en The Kruger National Park (KNP) research supersites were designed to encourage place-based research in order to geographically focus research activities on known and well described study sites as opposed to ad hoc site selection practiced previously. This was done by (i) delineating sites using a clear rationale, (ii) providing basic meta-data for these sites, and (iii) actively encouraging scientists to conduct research on these sites and share data freely. The underlying concept was that geographically focused research would facilitate data and knowledge exchanges and lead to long-term, multi-scaled and cross-disciplinary studies at these data-rich sites, facilitating an integrated and collectively developed understanding that would be hard to achieve otherwise. This essay acts as a short-term reflection on the KNP supersites and an introductory text for the special issue focusing on the outcomes from a multi-disciplinary study conducted on the southern granitic supersite. It starts off by briefly introducing the supersite concept, followed by a reflection on the achievements and challenges towards achieving the main objectives of the supersites. In addition, and as part of the "data-begets-data" philosophy underlying the supersites (i.e positive feedback of place-based data attracting further research and hence collection of further data), updated lists of references and available datasets are provided.CONSERVATION IMPLICATIONS: This paper highlights the successes and challenges of geographically focusing research in the KNP to the research supersites in order to facilitate integrative and multi-scaled learning in savanna systems. It also provides updated lists of references and available datasets to further stimulate research at these sites <![CDATA[<b>A tribute to Pieter Johannes (Johann) du Preez</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0075-64582020000200015&lng=en&nrm=iso&tlng=en The Kruger National Park (KNP) research supersites were designed to encourage place-based research in order to geographically focus research activities on known and well described study sites as opposed to ad hoc site selection practiced previously. This was done by (i) delineating sites using a clear rationale, (ii) providing basic meta-data for these sites, and (iii) actively encouraging scientists to conduct research on these sites and share data freely. The underlying concept was that geographically focused research would facilitate data and knowledge exchanges and lead to long-term, multi-scaled and cross-disciplinary studies at these data-rich sites, facilitating an integrated and collectively developed understanding that would be hard to achieve otherwise. This essay acts as a short-term reflection on the KNP supersites and an introductory text for the special issue focusing on the outcomes from a multi-disciplinary study conducted on the southern granitic supersite. It starts off by briefly introducing the supersite concept, followed by a reflection on the achievements and challenges towards achieving the main objectives of the supersites. In addition, and as part of the "data-begets-data" philosophy underlying the supersites (i.e positive feedback of place-based data attracting further research and hence collection of further data), updated lists of references and available datasets are provided.CONSERVATION IMPLICATIONS: This paper highlights the successes and challenges of geographically focusing research in the KNP to the research supersites in order to facilitate integrative and multi-scaled learning in savanna systems. It also provides updated lists of references and available datasets to further stimulate research at these sites