Characterising connectivity for fragmented landscapes in support of regional planning and impact assessment

Tiang, Darrel Chin Fung (2023) Characterising connectivity for fragmented landscapes in support of regional planning and impact assessment. MPhil thesis, University of Nottingham.

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Biodiversity loss resulting from habitat fragmentation and land use change is occurring at an increasing rate globally. Fragmentation can lead to genetic isolation within or between populations, due to loss in connectivity. The issue of ensuring ecological protection of fragmented areas must be addressed. Methods for accurately characterising connectivity within a landscape and integrating the study of connectivity loss into impact assessments is crucial. This thesis addresses this gap. It: (1) investigates the extent of ecological connectivity has been considered as part of infrastructure impact assessments (2) characterises connectivity for landscapes fragmented by agriculture, by considering how fine-scaled vegetation such as scattered trees support connectivity and the implications of ignoring such elements have on land use planning and (3) applies a spatially explicit scenario analysis of alternative road alignments and mitigation options to address common criticisms of the lack of consideration of connectivity in environmental impact assessments.

This work begins by providing a systematic review on the extent of ecological connectivity research in the context of linear infrastructure Environmental Impact Assessments (EIAs). that the review revealed that there is a lack of consideration of specific locational impacts or design alternatives for reducing harmful impacts to biodiversity, in linear infrastructure EIA. There is also much uncertainty regarding best methods and metrics to quantify and compare between multiple design options, and it is evident that research seldom recommends mitigation measures or their specific locations in environmental impact assessments. It is necessary to develop quantitative approaches for assessing the effects of transport networks on landscape connectivity at large spatial scales. It is shown in this chapter that while such approaches do exist, there are few published instances compared to the global geographic scope and scale of infrastructure projects; consequently, there are few examples from which to draw upon. Overall, the review showed a lack of standardised and efficient procedures to guide EIAs and decision making. The need for such procedures is made imperative by the increases in the number and extent of infrastructure developments, many of which require environmental impact assessments.

Subsequently, an assessment of connectivity within a fragmented landscape dominated by agriculture and pasture was conducted. It demonstrated how fine-scaled vegetation such as scattered trees support connectivity and the implications of ignoring such elements in regional scale land use planning. Modern connectivity modelling techniques rarely consider fine-scale movement patterns associated with movement between fine-scaled structural connectivity features, such as scattered trees, roadside corridors, and small habitat patches. This connectivity assessment mapped scattered trees in an agricultural area where pasture was the predominant human-altered land cover, then used a least-cost path analysis and a graph-theoretic approach to show that by ignoring scattered trees, simulated movement patterns do not match typical movement patterns seen in field research. The work showed that connectivity models that omit fine-scale landscape elements may misrepresent connectivity patterns.

Building on our findings above, we attempted to address common shortcomings of infrastructure EIAs. Construction of roads is one of the leading causes of habitat fragmentation and biodiversity loss on a global scale. This study represents the first research to combine both a scenario assessment and an evaluation of mitigation strategies for a road infrastructure project. It applied a spatially explicit connectivity model that considers fine-scale movement patterns, along with scenario analysis of alternative road alignments for a bypass in the Australian town of Beaufort. The wildlife connectivity model used expert-based parameterization of species movement traits and a combination of least-cost pathways, circuit theory, and graph theory to represent five conservation targets with contrasting dispersal abilities and habitat needs. For each of target, impacts of four distinct road alignments were modelled, with mitigation measures and alternatives routes then evaluated to identify the least damaging. The results demonstrated that each conservation target was affected differently, with terrestrial species with greater dispersal distances being the most affected. However, the modelling indicated that one alignment option had least impact overall, and that combining this route with wildlife crossing structures increases connectivity for all conservation targets. This real-world case study demonstrated the feasibility of integrating ecological connectivity modelling with scenario analysis in EIAs using a clear and quantitative manner.

The work presented in this thesis shows how fine-scale movement patterns can be characterised and modelled, and incorporated into EIAs and mitigation proposals for infrastructure development. It shows how specific measures can avoid, minimise, or mitigate adverse effects from infrastructure development, and more broadly to help land managers identify important conservation values that are often ignored. The quantitative assessments and models show how knowledge about dispersal networks, and the availability and distribution of suitable and accessible habitat can be used assess the effects of land use changes on a region's fauna and flora. Different species experience habitat fragmentation in different ways and at different scales, underlining the necessity for species-specific EIAs undertaken at appropriate at spatial scales.

Item Type: Thesis (University of Nottingham only) (MPhil)
Supervisors: Lechner, Alex
Gibbins, Christopher
Keywords: ecology; biodiversity; landscapes fragmented; environmental impact assessments
Subjects: Q Science > QH Natural history. Biology
Faculties/Schools: University of Nottingham, Malaysia > Faculty of Science and Engineering — Science > School of Environmental and Geographical Sciences
Item ID: 73704
Depositing User: TIANG, Darrel
Date Deposited: 22 Jul 2023 04:40
Last Modified: 24 Jul 2023 02:08

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