Ecological corridors in urban landscapes: identifying and assessing an ecological corridor in Johannesburg

Mckendry, Tyrone Brent
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With the ever increasing rate of urbanisation, and the negative impacts that it has on ecosystems and biodiversity, urban ecologists must find effective and sustainable conservation strategies to implement in the future. Ecological corridors have been suggested as one possible management strategy for the conservation of urban wildlife in isolated habitat fragments. Increasing the level of connectivity between habitat patches by creating corridors is believed to allow for the integration of populations into a single demographic unit, thus improving the probability of survival. This study sought to assess the value of an ecological corridor (n=1) in Johannesburg. The corridor was identified using spatial mapping software and assessed against a number of landscape criteria essential for a functional corridor. Based on this assessment, one corridor was identified for further research. A focal mammal species was used to perform a least-cost path analysis on the selected corridor to determine a suitable route for wildlife movement along the corridor. Vegetation structure, cover and composition were assessed on site and all three sampling sites along the corridor were found to be comparable in both structure and species composition. A Generalised Linear Model showed no significant differences in vegetation structure or composition between sites, nor were there any significant differences between plant species richness and disturbance or vegetation structure and disturbance. Only one site had a lower percentage of exotic plant species which may be attributed to good land management. Camera traps and live trapping were used to record the (<50 kg) small mammal species richness at each site. A total of 13 small mammal species were recorded in the corridor. Two of the study sites yielded higher small mammal species richness values than the third site which is a protected area but the result was not significant. This may indicate a lack of connectivity between this site and the rest of the corridor. This study suggests that an urban ecological corridor that is being impacted by urbanisation is still able to provide habitat for small mammals and possibly allow for movement within the urban matrix. However, the presence and absence of species within the corridor does not take into consideration population demography which may be influenced by factors such as social behaviour. Therefore, the overall effectiveness of the urban ecological corridor as a management strategy will likely require careful consideration of not only the habitat characteristics of the corridor but also the genetic, behavioural and demographic parameters of a particular target species
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfillment of the requirements for the degree of Master of Science February 2019 in Johannesburg