Ecological connectivity networks in rapidly expanding cities.

Amal Najihah M Nor,Ron Corstanje,Gavin M Siriwardena,Darren R Grafius,Jim A Harris

doi:10.1016/j.heliyon.2017.e00325

Amal Najihah M Nor, Ron Corstanje + Show 3 more

Open Access

https://doi.org/10.1016/j.heliyon.2017.e00325

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Abstract

Urban expansion increases fragmentation of the landscape. In effect, fragmentation decreases connectivity, causes green space loss and impacts upon the ecology and function of green space. Restoration of the functionality of green space often requires restoring the ecological connectivity of this green space within the city matrix. However, identifying ecological corridors that integrate different structural and functional connectivity of green space remains vague. Assessing connectivity for developing an ecological network by using efficient models is essential to improve these networks under rapid urban expansion. This paper presents a novel methodological approach to assess and model connectivity for the Eurasian tree sparrow (Passer montanus) and Yellow-vented bulbul (Pycnonotus goiavier) in three cities (Kuala Lumpur, Malaysia; Jakarta, Indonesia and Metro Manila, Philippines). The approach identifies potential priority corridors for ecological connectivity networks. The study combined circuit models, connectivity analysis and least-cost models to identify potential corridors by integrating structure and function of green space patches to provide reliable ecological connectivity network models in the cities. Relevant parameters such as landscape resistance and green space structure (vegetation density, patch size and patch distance) were derived from an expert and literature-based approach based on the preference of bird behaviour. The integrated models allowed the assessment of connectivity for both species using different measures of green space structure revealing the potential corridors and least-cost pathways for both bird species at the patch sites. The implementation of improvements to the identified corridors could increase the connectivity of green space. This study provides examples of how combining models can contribute to the improvement of ecological networks in rapidly expanding cities and demonstrates the usefulness of such models for biodiversity conservation and urban planning.

Highlights

In urban systems, green spaces play a key role in conserving biodiversity in a sustainable landscape by providing habitat, food sources and connectivity between groups which otherwise would be isolated by the urban matrix [1, 2]
The results suggest that planning for priority corridors should be developed at the link between patches which have low values of least-cost path lengths (LCP length) and effective resistances (EffResist), for example, Kuala Lumpur showed the lowest effective resistance value followed by Jakarta and Metro Manila (Table 6)
We can conclude that the popular least-cost model is an efficient and reliable method to identify corridors for which maintenance and improvement have to be prioritized to establish and implement ecological networks

Summary

Introduction

Green spaces play a key role in conserving biodiversity in a sustainable landscape by providing habitat, food sources and connectivity between groups which otherwise would be isolated by the urban matrix [1, 2]. Urban expansion has increased fragmentation in the landscape and has eliminated green space, dispersal corridors [5]. In this regard, fragmentation decreases connectivity, increasing isolation of habitats and green space loss [5]. Conservation of green space connectivity through ecological networks in rapidly expanding cities is needed to protect the biodiversity in urban area

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