An assessment of the potential biodiversity impacts from biofuel production in South Africa

[摘要] ENGLISH ABSTRACT: Biofuels are being promoted as a global necessity to meet climate change targetsthrough the replacement of fossil fuels. Many countries have identified biofuels as apotential mechanism to meet these challenges, with policy directives driving biofuelproduction. The South African government has proposed that biofuels form part of thecountry's future renewable energy and has proposed a draft biofuel strategy. This studyaims to investigate appropriate approaches to determine potential biodiversity impactsfrom biofuel production.Since biofuels are not currently grown to any large extent in South Africa, impact wasmodelled using future scenarios of converting available land within the Eastern CapeProvince of South Africa. Suitable species were identified using the species distributionmodelling programme MaxEnt. Some of the proposed biofuel crops were considered asinvasive (i.e. they spread from sites where they are cultivated) or are very likely to beinvasive in South Africa. This study also highlighted the considerable overlap betweensuitable growing areas and areas considered important for future biodiversityconservation.The biodiversity intactness index (BII), a broad based biodiversity indicator, was usedto assess the biodiversity implications of transforming available land to biofuels. The BIIindicates losses of biodiversity between 17.6% and 42.1% for the land use scenariosidentified. An important finding was that excluding important biodiversity areas thatoccur outside of protected areas can reduce biodiversity losses by as much as 13% andmaintain an overall intactness of ~70%. Currently the BII does not account forfragmentation or landscape configuration. This was addressed by developing a revisedbiodiversity intactness index (R-BII) which included the effect of patch-size and habitatfragmentation on biodiversity intactness. This study found that although the original BIIreported on the biodiversity trends of large-scale shifts in land-use across multiplescales it could not detect changes in landscape configuration which was reflected by theR-BII.Land-use change can impact on ecosystem processes that underpin the provisioning ofecosystem services by changing the combinations of species and the plant functional traits within communities. The impacts of cultivating potential biofuel species (Acaciamearnsii, Sorghum halepense and Eucalyptus species) were investigated using a plantfunctional traits approach. These species were shown to affect the leaf nitrogen content,leaf phosphorous content and leaf dry matter content associated with importantecosystem functions within an ecosystem service hotspot in the Eastern Cape. A declinein functional diversity was reported for all transformed land-uses by as much as ~40%.These shifts may be used to identify potential changes to ecosystem services associatedwith natural vegetation.The methods used in this thesis highlight the overall relevance of this work and itsimportance to minimising biodiversity resulting from biofuel production. Some of thekey findings address resolving spatial conflict, using biodiversity indicators, assessingimpacts of potential invasive species and planning for ecosystem services. New driversof change to land-use, such as biofuel production, are a major challenge to conservationbiologists and planners and the insights derived in from this study can be successfullyapplied to guide biofuel production.

[发布机构] Stellenbosch University