The fragmentation and loss of habitat reduce wildlife connectivity, leading to a constriction of species movement and an increase in the risk of extinction (Richards et al., 2017; Scolozzi & Geneletti, 2012; Syphard et al., 2011; Vergnes et al., 2012). In urban environments, green spaces are isolated by a matrix of buildings and roads, which restricts movement between green spaces such as urban forests and parklands (Goddard et al., 2010; Nor, Corstanje, Harris, & Brewer, 2017). Urbanisation is a significant cause of habitat fragmentation, particularly in low- and middle-income countries, where cities are rapidly urbanising due to high rates of population growth, rural-urban migration, and economic modernisation (Lechner et al., 2020; Richards et al., 2017; Richards & Belcher, 2019; Shathy, 2016).
Southeast Asia is one of the most rapidly urbanising regions in the world, with poorly planned cities resulting in habitat degradation, loss, and fragmentation, negatively impacting on biodiversity and urban ecosystem services (Lourdes et al., 2021; Richards et al., 2017; Seto et al., 2012). Urbanisation in Southeast Asia is of particular concern for conservation globally, as the region is home to four out of 34 of the planet’s biodiversity hotspots (Myers et al., 2000), and many of the countries in the region still have some relatively intact landscapes with high forest cover (Lechner et al., 2021; Hughes, 2017; Wilcove et al., 2013). Southeast Asia is also undergoing rapid social and environmental changes due to infrastructure development spurned on by increasing investment such as in transport networks (Ng et al., 2020; Teo et al., 2019) and massive urban development schemes such as Indonesia’s new planned capital Borneo (Teo et al., 2020). However, in Southeast Asia - unlike many cities in the highly urbanised Global North - urban green spaces such as in the Greater Kuala Lumpur, an urban conurbation with a population of around 7.5 million people, have the capacity to support biodiversity, even though they are found with a high-density urban matrix (Aida et al., 2016; Samantha et al., 2020; Tee et al., 2019a; Teo et al., 2021). Even within Southeast Asia, Greater Kuala Lumpur is remarkable for its rich wildlife, including threatened mammals like tapirs (Tapirus indicus), serows (Capricornis sumatrensis), gibbons (Hylobates bar), pig-tailed macaques (Macaca nemestrina), and pangolins (Manis javanica.
The continuing loss of biodiversity due to anthropogenic land use changes from urbanisation is especially concerning in countries like Malaysia, one of the most urbanised countries in Southeast Asia (United Nations, 2018). Malaysia's urbanisation percentage was 42% in 1980 and 76% in 2018 (United Nations, 2018). Urbanisation in Greater Kuala Lumpur has led to the loss of green space, including primary and secondary forest and former plantations (Mc Donald et al., 2008; Ramakreshnan et al., 2018; Seto et al., 2012), resulting in a decline of the total green space per capita from 13 m² in 2010 to 8.5 m² in 2014 (Kanniah & Siong, 2017). Clearly, given the rapid pace and scale of infrastructure development in Malaysia and other cities in the region, there is a need to protect and conserve existing green space before it is lost to development (Lechner et al., 2021). Conservation of green spaces for biodiversity and ecosystem services need to be embedded into planning, in particular ensuring that these cities incorporate urban greening efforts to ensure resiliency and support ecological processes such as connectivity (Lourdes et al., 2021; Sanusi & Bidin, 2020).
Characterising landscape connectivity using spatially explicit GIS modelling approaches is critical to realistically describe networks of urban green spaces and their potential to support urban planning approaches that considers and maintains biodiversity values (Honeck et al., 2020). While there are extensive examples of the application of connectivity modelling to urban environments in the Global North such as across Europe and North America (Balbi et al., 2021; Han & Keeffe, 2021; Serret et al., 2014; Tannier et al., 2016), there are very few examples in the tropics, in particular Southeast Asia with the majority of connectivity studies confined to agricultural or forested landscapes (e. g.: Brodie et al., 2015; Hearn et al., 2018; de la Torre et al., 2019). This study represents one of the first urban connectivity studies conducted in a Southeast Asian city.
Common approaches to modelling the impact of fragmentation on connectivity utilise graph theoretic approaches to characterise a landscape as a network of patches and linkages, and their importance for connecting landscapes (Minor & Urban, 2008; Rayfield et al., 2011). Potential for dispersal between patches are based on ecological characteristics such as minimum viable patch size and interpatch dispersal distance (Lechner, Doerr, et al., 2015; Tiang et al., 2021). In addition to quantifying the importance of patches and linkages using graph metrics, graph components can identify which groups of patches are interconnected but isolated from other groups of patches (Minor & Urban, 2008; Rayfield et al., 2011). The patterns in size and shape of these components can be used to characterise fragmentation and isolation (Lechner and Doerr, et al., 2015).
Underlying any connectivity modelling approach is spatial data describing land cover for characterising habitat and how the matrix may impede or support dispersal. In countries where urbanisation is rapid, major changes in land use can occur within a space of years and therefore it is essential to use spatial data that represent recent land cover (Ngo et al., 2020; Gao and O’Neill, 2020; Richards & Belcher, 2019). In Malaysia and many other developing countries, available spatial data are either not publicly available or have unsuitable spatial or temporal resolution. Remote sensing approaches utilising multi-date mosaics can be used to address cloud cover in Google Earth Engine (GEE), which is particularly problematic in the tropics, hold great potential for providing high quality inputs for connectivity modelling (Ang et al. 2021).
The objective of this paper is to characterise ecological connectivity for mammals within Greater Kuala Lumpur and identify important patches and linkages for connecting urban green spaces. We first map land cover across Greater Kuala Lumpur with GEE to identify potential habitat. We then model connectivity using the remote sensing data, expert-based parameterisation, and graph metrics for a range of dispersal guilds representing small and medium terrestrial and arboreal mammals. We conclude by discussing how such methods could be rapidly applied to other urban areas and the implication of the analysis for connecting urban habitat in the tropics such as in Greater Kuala Lumpur, and other highly urbanising and fast developing Southeast Asian cities.