Julia van Schalkwyk arthropod sampling in Houwhoek Nature Reserve

Sustainable land use study

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Sustainable land use study

Our KBR GreenMatter Mapula Scholar, Julia van Schalkwyk, provided us with a progress report on her doctoral study aimed at improving our knowledge about the biodiversity in the Kogelberg Biosphere Reserve. Her project aims to determine the value of the buffer and transition zones for biodiversity conservation, with the focus on plants and arthropods (insects, spiders and scorpions).

Julia van Schalkwyk sampling arthropods

Sampling arthropods in natural fynbos adjacent to apple orchards (near Groenlandberg Nature Reserve)

In most parts of the world, arthropod biomass and abundance dominate biodiversity, making them a vital part of ecosystems. Arthropods play important functional roles, such as improving soil structure, nutrient cycling, pollination and seed dispersal, as well as maintaining plant community composition and other animal populations, thereby contributing significantly to conservation.  In a large conservation area such as the Kruger National Park, as many as 50 000 to 60 000 species of insects could occur, with a biomass exceeding that of the mammal population.

Within the transition zone Julia is specifically looking at the impact of the deciduous fruit industry on arthropods. Unraveling the processes that drive community assembly is of particular importance for conservation in this highly fragmented region, and may contribute to successful conservation within the KBR. This is especially important within the buffer zone, which, if properly managed, can be extended to improve the long term conservation success of core areas.

Julia van Schalkwyk measuring local environmental variables

Measuring local environmental variables in an orchard

Factors within the natural landscape that may influence arthropod diversity are also investigated. These include the toposcape, that refers to differences in elevation and aspect and is important for the KBR since the transition zones tend to be restricted to lower elevations, core areas to higher elevations, and buffers in between these two, and local scale variables, such as physical characteristics of the habitat (vegetation structure, how rocky the habitat is, soil moisture, temperature) and plant species richness and composition.

The project will hopefully help us understand the natural arthropod diversity patterns within this biosphere reserve and how disturbed areas in the buffer and transition areas influence these values.

Julia van Schalkwyk arthropod sampling in Houwhoek Nature Reserve

Arthropod sampling in Houwhoek Nature Reserve

Julia’s overall progress to date is that her project proposal was presented to the University of Stellenbosch’s Department of Conservation Ecology and Entomology in May 2015, fieldwork started during the first available season of last year (October) with the sampling of  a total of 56 sites – 21 in the core area; 15 in buffer areas and 20 in transects from orchards into fynbos – using methods like pitfall trapping, sweep netting, and D-vac (modified leaf blower), and the first sorting of the collected data as well as the plant and arthropod samples. Since the last field work session, effort has been focused on identifying plant specimens.

So far she has identified more than 100 plant morphs (and still counting), and is now in the process of identifying most of these to species level. It is difficult to give an estimate of the number of arthropod species she hopes to find, but she expects there will be considerable energy required in sorting them all.

Julia van Schalkwyk - vegetation survey

Vegetation survey in Groenlandberg Nature Reserve

Among the problems encountered was the destruction of nine sites in the Houwhoek Nature Reserve with the Elgin fire of January 2016. Replacement sites are currently being identified

 

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  Vol 3, Issue 1 - March 2016.