Results
Subproject 2 is yielding fascinating results already. Biological surveys undertaken during 2014 and 2015 at two villages in northern Limpopo revealed exceptionally diverse communities of bats, mammalian carnivores, rodents, birds, ants and beetles (spiders were also collected but remain to be analysed). Species richness of all groups was comparable with values recorded from the nearby Soutpansberg Mountains, a globally-recognised biodiversity hotspot for many plants and animals. These multi-taxon surveys were carried out in the same spatial and temporal framework and accompanied by additional environmental datasets, such as LIDAR, allowing us to begin to gain an understanding of the landscape drivers of species richness turnover in diverse vertebrate and invertebrate taxa. Since these native communities are expected to provide important ecosystem services (predation, pollination, soil aeration) and to function as biological indicators of disturbance, their persistence in human-modified settlements, agricultural fields and rangelands was encouraging. However, it is clear that unsustainable resource use practices will impact negatively in the short to medium term on biodiversity and related ecosystem services. For example, fuelwood extraction has denuded the landscape of large trees which are important habitats for some birds and bats. The surveys revealed some unexpected "treasures" including rare and unusual species such as woolly bats (Kerivoula spp), Meller's mongoose and vampire ants.
Within the same subproject, we are attempting to quantify pollination and predation ecosystem services by native species within subtropical fruit orchards in the Levubu and Thohoyandou areas of northern Limpopo. To achieve this we excluded ants from mango trees in subsistence-farmer mango orchards and we excluded birds and birds from macadamia trees on six commercial macadamia orchards. Treatments of the latter involved day-time exclusion (excluding birds), night- time exclusion (excluding bats), complete exclusion (excluding birds and bats) and control treatments. While the pollination trials have been completed, the predation trials are in progress. Only in recent years have such predator exclusion trials been attempted in tropical regions. Teja Tscarntke and Peter Taylor contributed to a recent review paper on the topic of predator exclusion in tropical agroecosystems published in 2015 in "Biological Reviews".
A third component of the Subproject is exploring the use of controlled temperature trials to calculate "day-degree" models based on the development of the major macadamia pest-stinkbug (Bathycoelia indica), as well as to measure the responses of native ant species to a range of temperatures, allowing the development of mechanistic models to simulate the impacts of future climate change on local ant communities. These experiments are in progress and expected to be completed by mid-2016.
Within the same subproject, we are attempting to quantify pollination and predation ecosystem services by native species within subtropical fruit orchards in the Levubu and Thohoyandou areas of northern Limpopo. To achieve this we excluded ants from mango trees in subsistence-farmer mango orchards and we excluded birds and birds from macadamia trees on six commercial macadamia orchards. Treatments of the latter involved day-time exclusion (excluding birds), night- time exclusion (excluding bats), complete exclusion (excluding birds and bats) and control treatments. While the pollination trials have been completed, the predation trials are in progress. Only in recent years have such predator exclusion trials been attempted in tropical regions. Teja Tscarntke and Peter Taylor contributed to a recent review paper on the topic of predator exclusion in tropical agroecosystems published in 2015 in "Biological Reviews".
A third component of the Subproject is exploring the use of controlled temperature trials to calculate "day-degree" models based on the development of the major macadamia pest-stinkbug (Bathycoelia indica), as well as to measure the responses of native ant species to a range of temperatures, allowing the development of mechanistic models to simulate the impacts of future climate change on local ant communities. These experiments are in progress and expected to be completed by mid-2016.