Abstract
The extreme variability in the topography, altitude and climatic conditions in the temperate Grassland Mountains of Southern Africa is associated with the complex mosaic of grassland communities with pockets of woodland patches. Understanding the relationships between plant communities and environmental parameters is essential in biodiversity conservation, especially for current and future climate change predictions. This article focused on the spatial distribution of woodland communities and their associated environmental drivers in the Golden Gate Highlands (GGHNP) National Park in South Africa. A generalized linear model (GLM) assuming a binomial distribution, was used to determine the optimal environmental variables influencing the spatial distribution of the woodland communities. The Coefficient of Variation (CV) was relatively higher for the topographic ruggedness index (68.78%), topographic roughness index (68.03), aspect (60.04%), coarse fragments (37.46%) and the topographic wetness index (31.33) whereas soil pH, bulk density, sandy and clay contents had relatively less variation (2.39%, 3.23%, 7.56% and 8.46% respectively). In determining the optimal number of environmental variables influencing the spatial distribution of woodland communities, roughness index, topographic wetness index, soil coarse fragments, soil organic carbon, soil cation exchange capacity and remote-sensing based vegetation condition index were significant (p 0.05) and positively correlated with the woodland communities. Soil nitrogen, clay content, soil pH, fire and elevation were also significant but negatively correlated with the woodland communities. The area under the curve (AUC) of the receiver operating characteristics (ROC) was 0.81. This was indicative of a Parsimonious Model with explanatory predictive power for determination of optimal environmental variables in vegetation ecology.Conservation implications: The isolated woodland communities are sources of floristic diversity and important biogeographical links between larger forest areas in the wider Drakensberg region. They provide suitable habitats for a larger number of forest species and harbour some of the endemic tree species of South Africa. They also provide watershed protection and other important ecosystem services. Understanding the drivers influencing the spatial distribution and persistence of these woodland communities is therefore key to conservation planning in the area.
Highlights
Several studies across the world have attempted to predict the impact of environmental factors on the spatial distribution of plant communities in different landscapes (Hutyra et al 2005; Salazar, Nobre & Oyama 2007)
We looked at the spatial distribution of the woodland communities and their associated environmental drivers
Using Gate Highlands National Park (GGHNP) broad vegetation map and classification by Manfred (1990), woodland polygons were grouped into four different categories (Figure 3), namely Afromontane forests (Olinia, Podocarpus, Kiggelaria), Euclea woodland, Leucosidea woodland, and Protea woodland
Summary
Several studies across the world have attempted to predict the impact of environmental factors on the spatial distribution of plant communities in different landscapes (Hutyra et al 2005; Salazar, Nobre & Oyama 2007). The findings from these studies predict changes in dry woodland and Afromontane forests because of climatic changes. Previous studies on structural and floristic composition of the Afromontane forests and other woodland communities in Golden Gate Highlands National Park (GGHNP) were restricted to a smaller area before the expansion of the park to its current footprint (Manfred 1990).
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.