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climate change adaptation strategies.

      1.5.1 Ecosystem Services

Ecosystem health represents the system resilience, organisation, and vigour for the sustainable functioning (Costanza 1992). Ecosystem services are the major components of ecosystem health which not only provide benefits to the humankind but also help in regulating the overall functioning of an ecosystem (Verma et al. 2020b). For example, urban and peri‐urban forests help the urban society to tackle many of the issues such as protection from heat waves, flood/stormwater, pollution, etc. related to their livelihood (Green et al. 2016; Livesley et al. 2016). A few major ecosystem services (provisioning, supporting, cultural, and regulatory) provided by the urban vegetation include the temperature mitigation (urban cooling), noise level reduction, air purification, climate mitigation, nutrient cycling, C‐sequestration, pollination, providing food (garden and farms), recreation opportunities, ecotourism, run‐off mitigation, waste decomposition and detoxification, habitat for biodiversity, etc. (Steiner 2014; Dallimer et al. 2016; Aronson et al. 2017; Richards et al. 2019; Pedersen Zari 2019). Enumeration of ecosystem services of the urban ecosystems can be done by basic mapping to the valuation and management (McDonald and Marcotullio 2011). However, the extent of ecosystem services demanded by and provided to the urban dwellers varies from city to city throughout the world (Lososová et al. 2018; Richards et al. 2019). Moreover, an increase in extreme weather events has been reported to disrupt the provisioning of ecosystem services, causing an emerging challenge for finding appropriate adaptation measures (Wamsler et al. 2013). Site‐specific enumeration of ecology and climate conditions may help in developing ecosystem services‐based urban regeneration strategies (Pedersen Zari 2019). The ecosystem services are needed to be included in the major policy and decision‐making agendas related to the urban planning and designing in the changing climate scenarios (Pedersen Zari 2019). Thus, with the growth of urban population and climate change, finding the appropriate methods for improving the provisioning of ecosystem services is needed (Richards et al. 2019). Moreover, research on evaluating ecosystem services in the urban ecosystems from the tropical regions is also needed to be explored.

      1.5.2 Plant Adaptations

      Not all the species are sensitive to the higher temperature and drought conditions, as some of the species may escape these extreme conditions by developing resilience and adaptations. In a study on species distribution under varying ranges of the European regions, Lososová et al. (2018) reported that about 45% of species do not show any direct relationship with the geographical distribution and climatic conditions. Thus, with the ongoing climate change, several species have been expected to decline, whereas some other species (particularly alien) which showed resilience to the climate change may spread, particularly in the European urban ecosystems. In other words, the space/niches created due to the decline of a species would be filled up by those species which have the tendency to cope‐up with the increased temperature and drought conditions (Lososová et al. 2018). The fast‐growing annuals (herbs) respond more quickly to the environmental changes as compared to the perennial herbs and woody vegetation (Grime 2001), thus these species may have wider distribution ranges in the future. The ruderal life strategy, production of large number of seeds/propagules and self‐pollination traits help the annual herbs to track the environmental changes more quickly (Aarssen 1998; Lososová et al. 2018). Therefore, they are considered as the key indicators of the ongoing climate change. Further, the dominance of plants using the C₄ photosynthetic pathway has also been reported from the urban regions as compared to the non‐urban regions of the European countries (Duffy and Chown 2016). It is expected that the C₄ plant species have more adaptive capacity to the localised warming conditions created by the UHI effects in the European regions which can be a strategy for the shift in future vegetation cover in these regions with the climate change (Duffy and Chown 2016). Such type of studies related to the species composition and climate change adaptation are needed from the tropical regions of the world as well.

      1.5.3 Green Infrastructure

Green infrastructure is a strategic approach of landscape and environmental planning based on the principles of landscape and urban ecology (Niemelä 2014; Ramyar and Zarghami 2017). It represents the interconnected network of ecosystem structures such as green spaces (parks and gardens) and water bodies which are designed and managed for delivering numerous ecosystem services (European Commission 2013; Niemelä 2014; Green et al. 2016). These infrastructures are the critical components of the urban areas and provide several benefits to the humans in terms of ecological, environmental, and social challenges (Tzoulas and Greening 2011; Keniger et al. 2013; Ramyar and Zarghami 2017). Moreover, the concept of green infrastructure provides a common platform for scientists and researchers from ecology, social science, engineering, and landscape planners to interact and develop management systems for tackling different environmental issues (Pauleit et al. 2011). Green infrastructures can help in alleviating the impacts of UHI effect; however, UHI effect alternatively impacts the vegetation phenology, therefore, the role of these infrastructures in reducing UHI effect needs further research (Niemelä 2014; Dallimer et al. 2016). Therefore, increasing interests have been reported in investment in green infrastructure development and urban ecosystem regeneration in the recent years (Green et al. 2016). By having multiple benefits, green infrastructures are considered to play a major role in climate change adaptation (Ramyar and Zarghami 2017). Detailed viewpoint on different types of green infrastructures and their role in combating climate change has been given in the following sub‐sections.

      1.5.3.1 Green Space Development

      Urban greening programmes are the leading features of the policies related to the climate change mitigation (Weissert et al. 2014). In view of ongoing climate change, potential research and management emphasis has been given to identifying the impacts of socio‐demographic and environmental drivers on green spaces and the benefits derived from their conservation (Niemelä 2014; Verma et al. 2020c). The key tangible ecosystem services derived from the green spaces include mitigation of air pollution and UHI effect as well as physical and physiological health benefits to the residents (Verma et al. 2020b; Wang et al. 2020). Cooling effect provided by the green spaces is the most important ecosystem service which helps in mitigating UHI effect (Yu et al. 2017). The cooling effect of green spaces has been extensively explored by several researchers which involve two eco‐physiological mechanisms viz. evapotranspiration and shadowing (Jiao et al. 2017; Wang et al. 2020). Size and characteristics (shape, structure, and composition/configuration) of green space is more important for cooling effect as it increases with increasing size of the green spaces (Jaganmohan et al. 2016; Yu et al. 2017); however, it is still controversial and several other factors come into the play (Monteiro et al. 2016). However, there is a threshold value of efficiency (TVoE) above which increase in vegetation cover may not lead to a consequent decrease in land surface temperature (Bao et al. 2016; Yu et al. 2017). Tree‐based green spaces showed the highest cooling effect followed by bush and grassland (Kong et al. 2014). Since the canopy size and structure vary with the tree species, they provide different wind speed patterns which resulted in variable cooling effects (Armson et al. 2012). In addition, different trees have different eco‐physiological mechanisms (e.g. evapotranspiration and leaf area index) which depend on the resource availability and management practices (Wang et al. 2020). Kuang et al. (2015) observed a positive correlation between the cooling effect of green space and normalised difference vegetation index (NDVI). In addition, the presence of water bodies along with the green spaces improve the cooling effect. For example, green spaces connected with water bodies showed higher cooling effect, whereas grassland‐based green spaces showed weak cooling effect (Yang et al. 2020). Therefore, for climate change mitigation, interconnected green space and water body conservation and development are strongly suggested (Yu et al. 2017).

The magnitude of reduction of the temperature by one unit with the increase in vegetation (tree) cover is known as cooling efficiency (CE) which varies with the size and shape of the green spaces (Zhou et al. 2017; Wang et al. 2020). Compact green spaces with circular or square shapes provide more CE (Yu et al. 2017). Moreover, the regional climatic conditions also play

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