This paper aims to provide a baseline for conservation planning by documenting patterns of plant diversity and vegetation in the upper catchment of the Cuito River. 417 species are recorded from this region. Nine of these are species potentially new to science. Ten species are newly recorded from Angola, with an additional species only recorded previously within Angola from the northern enclave of Cabinda. The 108 new provincial records for Moxico clearly indicate the lack of collections from Angola’s largest province. We note the existence of extensive peat deposits in the Cuito river system for the first time and suggest that one of Barbosa’s vegetation types in the area needs to be reassessed.
Abstract. Van Staden N, Siebert SJ, Cilliers DP, Wilsenach D, Frisby AW. 2020. Floristic analysis of semi-arid mountain ecosystems of the Griqualand West centre of plant endemism, Northern Cape, South Africa. Biodiversitas 21: 1989-2002. The Griqualand West Centre (GWC) is one of 13 centres of plant endemism in South Africa. Despite its unique flora, it remains poorly conserved and studied. A recent study identified an extensive geographical core area for the GWC, but endemic plant species were found to be absent from certain parts within these borders. To address this, we refined the current GWC borders based on an ecological niche model, which predicted that endemic species are restricted to four mountain ranges within GWC. Mountain floras within these refined borders were then floristically compared to assess whether they are hotspots of endemicity. Floristically, the Asteraceae, Fabaceae, Malvaceae, and Poaceae were the dominant plant families. Mountain ecosystems differed from one another at species level, with indicator species explaining the compositional differences. Distribution patterns of indicator species were determined by mean annual precipitation, Ca: Mg ratios, soil pH, cation exchange capacity, iron, and sand content. These environmental factors are possible drivers of niche partitioning, environmental filtering and habitat specialization in each mountain ecosystem. Limestone and banded ironstone habitats were identified as conservation priority areas, since they contained the highest numbers of rare and threatened GWC restricted-range species, of which six were narrow endemics.
The co-existence of woody plants and grasses characterises savannas, with the horizontal and vertical spatial arrangement of trees creating a heterogeneous biotic environment. To understand the influence of biogeophysical drivers on the spatial patterns of 3D structure of woody vegetation, these patterns need to be explained over large areas to capture the context. The aim of the study was to produce an ecologically meaningful savanna classification using LiDAR (Light Detection and Ranging). We then applied the classification to detect change in a protected area (PA) and a communal rangeland (CR). Canopy height model (CHM) and volumetric pixel (voxel) data from the Carnegie Airborne Observatory-Alpha system were used to create the structural classification. Vegetation was classified as shrub (1-3 m), low tree (3-6 m), high tree (6-10 m) or tall tree (N10 m). A hierarchical a priori approach was used to develop classification criteria. Metrics were based on the cover and spatial arrangement of the height classes: Canopy Cover, Sub-canopy Cover, Canopy Layers, Simpson's Diversity Index and Cohesion. For change detection four of the metrics were used (Canopy Cover, Canopy Layers, Cohesion and Number of height classes present). Gains, losses and persistence (GLP) of cover at each height class and of the four structural metrics were calculated. GLP of clusters of each metric (calculated using Local Indicators of Spatial Association) were used to assess the changes. Trees N3 m in height showed gains up to 2.2 times higher in the CR where they are likely to be protected for cultural reasons, but losses of up to 3.2 times more in the PA, possibly due to treefall caused by elephant and/or fire. A 3D classification approach was successful in detecting fine scale, short term changes between land uses, and can thus be used as a monitoring tool for savanna woody vegetation structure.The Griqualand West Centre of plant endemism (GWC) is located in north-central South Africa, extending through parts of the Northern Cape and North-West provinces. It is a vast area (roughly 450 × 220 km) and larger than KwaZulu-Natal. The high local floristic diversity of the region is well knowna single survey by John Acocks in 1953 yielded more species per sample point than any other across South Africa. Despite this obvious diverse and endemic-rich edaphic flora, the GWC has remained vaguely defined and floristically poorly explored because of its large size, complex geology, complex mosaic of vegetation types and arid environment. The GWC was, prior to this study, only broadly defined based on its geology. This study aims to quantitatively test the existence, floristic composition and boundaries of the GWC. Data regarding the plant taxa present in the area, their affinities and distribution was sourced from the Plants of Southern Africa (POSA) database, literature surveys, herbarium collections and field work. Plant distributions were mapped with ArcGIS (ESRI 2011) and criteria were developed to classify taxa as endemic, near-endemic or flori...
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