园林景观设计生物多样性外文翻译文献

文献信息文献标题：Utilising exotic flora in support of urban indigenous biodiversity: lessons for landscape architecture（利用外来植物支持城市土著生物多样性：对景观建筑的经验教训）文献作者：Rastandeh A，Pedersen Zari M，K.Brown D，et al文献出处：《Landscape Research》,2018,43(5):708-720字数统计：英文3608单词，20220字符；中文6313汉字外文文献Utilising exotic flora in support of urban indigenousbiodiversity: lessons for landscape architecture Abstract Evidence shows that in the absence of intact natural habitats, some exotic patches of vegetation may play a compensatory role in supporting indigenous biodiversity in urban environments. This paper suggests that in urban settings where landscapes already contain non-natives, both indigenous and exotic flora may be necessary to maintain indigenous biodiversity. The research was constructed based upon a review of the current literature combined with a GIS-based spatial analysis of urban landscape patterns, using Wellington New Zealand as a case study. The research provides evidence concerning different aspects of utilising indigenous and exotic plant species to argue that a balanced proportion of indigenous to exotic plants may be advantageous in order to respond to some aspects of biodiversity loss. The results have three immediate implications for landscape architecture practices at the urban scale and reveal important issues that should be addressed by future research.KEYWORDS: exotic flora; indigenous biodiversity; landscape architecture; urban biodiversity1.Introduction: exotic-indigenous land coverThere is sufficient evidence to indicate that biodiversity is essential to support the healthy functioning of ecosystems (Balvanera et al., 2006; Cardinale et al., 2006; Lefcheck & Duffy, 2015) and to provide a wide range of ecosystem services supporting the quality of human life (Tzoulas et al., 2007; Colley, Brown, & Montarzino, 2016). Although urban biodiversity has received less attention in both research and practice (Niemelä, 1999; Alberti, 2005; Farinha-Marques, Lameiras, Fernandes, Silva, & Guilherme, 2011), there is a growing body of research on urban biodiversity worldwide (q.v. Müller & Kamada, 2011; Elmqvist et al., 2013) heralding a deeper understanding of the importance of urban biodiversity, regardless of it being indigenous or not. Particularly in the case of New Zealand, the question of indigenous vs. exotic biodiversity is extremely acute for at least two important reasons. First, New Zealand has been recognised as one of the world’s biodiversity hotspots (Myers, Mittermeier, Mittermeier, da Fonseca, & Kent, 2000). Geographical isolation of the country has resulted in a unique biodiversity. According to Brockie (2007), for example, about 80% of the 2500 species of native conifers, flowering plants and ferns are endemic to New Zealand. In addition, 71% of birds breeding in New Zealand before human arrival have been recognised as endemic species.Second, the introduction of a large number of exotic flora and fauna to the country has deeply affected New Zealand indigenous biodiversity (Allen & Lee, 2006). Since the early 1800s, Europeans have imported a wide range of exotic flora and fauna to New Zealand (Dawson, 2010). In addition, modification of land by humans has widely affected the indigenous state of the landscapes. Loss of most indigenous land cover in New Zealand has resulted (Walker, Price, & Rutledge, 2008). Since the 1300s, approximately 70% of New Zealand landscapes have been modified by humans causing the extinction of 32% of indigenous land and freshwater birds, 18% of endemic seabirds, 3 of 7 species of frogs, and at least 12 invertebrates (Statistics New Zealand, 2002). After the arrival of the first people to New Zealand more than a thousand years ago (Polynesians, now known as Māori and Moriori), hunting practices, the introduction of certain commensal animals (such as kurī, the now extinct in New Zealand Polynesian dog Canis familiaris and kiore, the Pacific orPolynesian rat Rattus exulans) and human-caused ecosystem loss (particularly clearing by fire of almost half of all lowland and montane forest) gave rise to the extinction of 34 endemic land birds and several endemic herpetofauna or at least significant declines in populations (Ministry for the Environment, 1997 cited in Craig et al., 2000; Towns & Daugherty, 1994; McGlone, 1989). Destruction of indigenous land cover and extinctions or population pressures of native species continued, with different causes and results, from the late 1700s when the first Europeans arrived in New Zealand.More than 86% of people in New Zealand live in cities (United Nations—Department of Economic & Social Affairs, Population Division, 2008), and there is a general consensus amongst New Zealand researchers of the importance of improving indigenous urban biodiversity (e.g. Freeman & Buck, 2003; Ignatieva, Stewart, & Meurk, 2011; Meurk, Blaschke, & Simcock, 2013; Meurk & Hall, 2006; Meurk & Swaffield, 2000; Pedersen Zari, 2012, 2015; Spellerberg & Given, 2008; Stewart et al., 2009; Swaffield, 2005). According to Clarkson, Wehi, and Brabyn (2007), only 1.96% of current urban New Zealand is the land cover type class ‘Indigenous Forest’ that is indicative of mature indigenous land cover. The loss of indigenous plant diversity in urban settings may be regarded as a threat to the survival of indigenous fauna as well. Research shows that there is a mutual relationship between a wide range of indigenous flora and fauna. Nevertheless, some exotic plant species can support indigenous fauna and this should not be set aside. Given that, it may be necessary to define a balance between indigenous and exotic land cover type classes in urban settings in order to maximise the performance of ecosystem services required both to support indigenous species and to maintain and/or improve the quality of human life. To this end, it is imperative firstly to identify the role of both indigenous and exotic flora in supporting indigenous fauna in urban settings, and secondly to build up an understanding of the relationships between indigenous and exotic land cover type classes and how they both contribute to overall urban biodiversity and thereby a higher level of ecosystem services.2.A middle ground: the coexistence of exotic–indigenous biodiversityThe aim of this research was to build up an understanding of the inevitable presence of indigenous and exotic flora in an urban environment, in order to determine the likely possibility of there being a ‘middle ground’ approach for employing a range of both indigenous and exotic land cover type classes in support of indigenous biodiversity, thereby giving rise to a higher provision of ecosystem services in an urban setting. The research methods involved (1) a review of the current literature on the influence of indigenous and exotic flora on biodiversity and (2) a case study of Wellington, New Zealand to reveal the current status of indigenous and exotic land cover type classes present in the study area using the Land Cover Data Base version 4.1 (hereafter LCDB) provided by Landcare Research (Landcare Research, 2015) and Geographic Information System (GIS). Scholarly publications containing empirical data were reviewed to identify if there could be advantages in using indigenous flora to support urban fauna and if so, what might be the most important types. The review also included consideration of both the advantages and the disadvantages of exotic flora in urban environments. The published data in the current literature were collected from peer-reviewed papers indexed in online scientific databases. While international examples were studied, more heed was given to research from New Zealand to provide a more focused and detailed literature review. Following this, given that there are two recognised indicators to measure indigenous biodiversity in New Zealand (the distribution of the little spotted kiwi (Apteryx owenii) as well as the percentage of indigenous vegetation in New Zealand land environments) (Department of Conservation, 2015; Statistics New Zealand, 2002), the latter indicator was used in this research to measure indigenousness in the study area. Thus, LCDB was utilised in the GIS environment in order to calculate the degree of indigenousness in terms of the 16 land cover type classes currently present in the study area.Layers were intersected separately by the Wellington Urban Zone boundary and the Wellington City Council Suburbs Boundaries (Wellington City Council Open Data Portal, 2015) in order to generate a new map demonstrating the study area based onthe land cover classification system defined by LCDB. The results have been illustrated in simple formats to provide an understandable picture of the current status of indigenous-to-exotic flora proportions in Wellington. Formally accepted definitions of land cover type classes were extracted from data provided by Landcare Research (2015) and were used as a basis for recognising whether each class should be classified as indigenous or exotic. This study reveals a number of key implications for the landscape architecture discipline which may be considered as a basis for any future intervention in the existing landscape pattern composition and configuration including land allocation for future housing and infrastructure planning as well as management and development of current green and open spaces.3.The effects of flora on faunaSome researchers have established a connection between indigenous vegetation and overall levels of biodiversity (Fischer, Lindenmayer, & Hobbs, 2009). This can mean that a greater proportion of land covered by indigenous flora may positively be correlated with greater biodiversity. Empirical research suggests that when a landscape consists of more than 30% indigenous plants, the adverse effects of fragmentation on wildlife species will be reduced to an acceptable level (Andrén, 1994). A study of 22 cities across the world, including five cities in the Southern Hemisphere (Adelaide, Auckland, Durban, Melbourne and Singapore), indicated that the percentage of indigenous vegetation in urbanised landscapes is negatively correlated with the extinction rate of indigenous plants (Hahs et al., 2009). Recently, Aronson et al. (2014) studied more than 100 cities worldwide including three cities in New Zealand (Auckland, Dunedin and Hamilton) and found that indigenous vegetation supports higher concentrations of both indigenous and exotic bird and plant species.In the New Zealand landscape architecture research context, indigenous vegetation in human-modified landscapes is proposed to decrease the biosecurity risks imposed by some exotic species (Meurk & Swaffield, 2000, 2007). According to Meurk (1999), at least 20% of the total land area in modified landscapes is required tobe indigenous land cover type classes to ensure the survival of indigenous biodiversity in urban New Zealand. The overall results of empirical research conducted by New Zealand researchers are testimony to the fact that indigenous fauna are extremely dependent on indigenous flora. For example, the mutual ecological relationship between lizards, skinks and some indigenous plants has been observed and proved (Whitaker, 1987; Wotton, 2002). In other research in New Zealand, Clout and Gaze (1984) showed the necessary ecological connection between indigenous forests and indigenous birds. A four-year (1993–97) study of endemic long-tailed bats in Lower Eglington Valley in the Fiordland National Park in the South Island found that very mature (c. 100 years to more than 600 years of age) indigenous trees are actively chosen by bats for roosting. In addition, New Zealand indigenous invertebrates require indigenous plants to survive (Patrick, 1994). There is also evidence, however, that some exotic flora can be advantageous to indigenous biodiversity. For example, some researchers including Fischer et al. (2009) and Szlavecz, Warren, and Pickett (2011) believe that in the absence of intact indigenousness, exotic flora may play a compensatory role in supporting indigenous fauna. Moreover, the findings of some studies reveal that indigenous urban birds may depend on exotic plants to survive (Corlett, 2005). In New Zealand, studies have also been undertaken investigating the significance of exotic flora in support of indigenous fauna. A review conducted by Pawson, Ecroyd, Seaton, Shaw, and Brockerhoff (2010) provided details of the relationship between exotic flora and indigenous fauna, specifically threatened species, and confirmed that a considerable number of New Zealand indigenous fauna may obtain benefits from exotic flora in different ways.4.Case study: Wellington New ZealandWellington, the capital of New Zealand (41°16 S, 174°45 E) has a population of about 203,000 people (Wellington City Council, 2015). This figure is projected to climb to 246,000 by the end of 2043 and therefore there is a need to construct an additional 21 400 dwellings. Currently, about 39.93% of the total study area has been built on and the remainder of the land is covered by a wide range of green and openspaces.Although there seems to be a great proportion of urban green space (≈400 m2 per capita), this figure can be misleading from an ecological point of view because many of the land cover type classes are unlikely to directly support indigenous urban fauna at the present time. Overall, due to a wide range of reasons including the destruction of wildlife habitats, low density urbanisation and the introduction of exotic species (Allen & Lee, 2006; Bagnall, 1979; Towns & Daugherty, 1994) the loss of indigenous biodiversity has been accelerating in Wellington since the 1800s. Furthermore, climate change, more specifically warmer-than-average temperatures, is likely to change the current proportion of indigenous and exotic flora in favour of the latter (McGlone & Walker, 2011). Landcare Research has provided a spatial database of the entire New Zealand landmass (Landcare Research, 2015). The current version, LCDB v.4.1, includes 33 land cover type classes facilitating research on ecology and biodiversity at different scales, including those of urban landscapes.5.Analysis of the existing land cover types and research findingsAs an initial step to provide a detailed insight into the ecological reality of the study area, the database was utilised by the authors in the software Arc GIS to quantify the existing land cover type classes and their spatial distribution in the Wellington urban zone. The output revealed that the study area is a heterogeneous landscape in terms of land cover type classes consisting of 16 land cover type classes.The present research shows that urban Wellington, like elsewhere in New Zealand (Walker, Price, Rutledge, Stephens, & Lee, 2006; Walker et al., 2008), is suffering severely from a loss of indigenous biodiversity (Pedersen Zari, 2015). Although the landscape is at first sight diverse, the calculations made in the GIS environment showed that out of sixteen land cover type classes present in the study area only four are indigenous classes, namely Broadleaved Indigenous Hardwoods (22.98%), Indigenous Forest (0.9%), Matagouri or Grey Scrub (0.22%) and Herbaceous Freshwater Vegetation (<0.02%). Amongst them, only Indigenous Forest (0.9%) is a mature indigenous land cover type class capable of ensuring indigenousbiodiversity and thereby high-quality ecosystem services, although broadleaved indigenous hardwoods have the potential to become mature indigenous forest over time.6.Implications for landscape architecture6.1.The importance of scale and resolutionAn initial finding of this study is that spatial resolution and the availability of a land cover type classification system play a key role in identifying and plotting the land cover type classes present in the area under study. In other words, the spatial resolution of data needs to be sufficiently fine-grained to reveal detailed ecological information about a wide range of land cover type classes. Thus, a detailed classification system is required to address urban biodiversity. A detailed land cover type classification system provides opportunities to analyse urban landscapes spatially and reveal issues which are unlikely to be easily diagnosed and understood through using a less detailed classification system. This point has been previously underscored by other researchers (Freeman & Buck, 2003). The platform, fortunately, has been already provided in New Zealand by Landcare Research. Using LCDB, it can be calculated, for example, that only 121.7 ha of the total study area of 13 511.3 ha consists of indigenous forest that is indicative of a mature indigenous land cover type class in the study area representing intact natural patches of vegetation before the arrival of humans. Therefore, the individual share of each Wellington resident of the existing indigenous forests is only about 6 m2 (out of approx. 400 m2 of green/open space per capita). This difference may be enlightening for urban policy-makers, reinforcing the need for landscape architecture researchers to employ a similarly rich land cover type classification system when addressing urban biodiversity issues to avoid misconceptions concerning urban green/open spaces. Furthermore, this difference reemphasises the importance of scale (Cushman & McGarigal, 2008) and the key role of the land cover type classification system (Botequilha Leitão, Miller, Ahern, & McGarigal, 2006) when doing research on biodiversity. Based upon such a detailed database, land cover type classes in the study area can be generallycategorised into exotic and indigenous. In total four indigenous land cover type classes are present in the study area namely Broadleaved Indigenous Hardwoods (22.98%), Indigenous Forest (0.9%), Matagouri and/or Grey Scrub (0.22%) and Herbaceous Freshwater Vegetation (< 0.02%). Moreover, five exotic land cover type classes were also identified in the study area namely Gorse and/or Broom (12.53%), High Producing Exotic Grassland (11.06%), Exotic Forest (6.23%), Urban Parkland and/or Open Space (3.02%) and Low Producing Grassland (2.55%).6.2.Ecological succession opportunitiesEcological succession is a naturally or anthropogenically caused process through which one ecosystem (i.e. land cover type) is gradually transformed into another. According to LCDB, left undisturbed, patches of vegetation covered by gorse (Ulex europaeus) and/or broom (Cytisus scoparius) can be converted into broadleaved indigenous hardwoods and these, in turn, can be transitioned towards indigenous forest over time. There is ample evidence to show that gorse and broom are very likely to be replaced by indigenous flora under suitable circumstances (Williams, 2011). Currently, 12.53 and 22.98% of the Wellington urban landscape is covered by the classes gorse/broom and broadleaved indigenous hardwoods, respectively, providing great successional opportunities for landscape regeneration in favour of indigenous land cover type classes, such as indigenous forest. Given that at least 21 400 new dwellings need to be constructed in urban Wellington by the year 2043 in order to respond to the projected urban population growth (Wellington City Council, 2015), identifying the spatial dispersal of the potential land cover type classes capable of transition towards indigenous forests holds the key to avoiding misallocation of land to future housing and infrastructure development in the coming decades. For example, allocation of lands covered by gorse and/or broom for urban development (e.g. new houses and land associated with essential infrastructure, such as transportation facilities and power lines) may deprive the study area of landscape regeneration opportunities over time.pensatory roles of exotic floraIn urban areas that already contain non-natives, some exotic flora may play acompensatory role in supporting indigenous urban fauna. Therefore, it is necessary to recognise the possible benefits of exotic flora. For example, patches of exotic vegetation can be regarded as stepping stones in order to facilitate the movement of urban fauna, such as birds between patches of indigenous vegetation. This type of spatial connectivity, however, may concurrently increase the risk of pest and weed dispersal from one patch to another (Sullivan, Meurk, Whaley, & Simcock, 2009). Therefore, debate on spatial connectivity remains an area of conflict in urban biodiversity research (Barnes, 2000; Botequilha Leitão et al. 2006, passim). Exotic flora may be also utilised as a barrier to anthropogenic or climatic edge effects (Murcia, 1995) such as air and noise pollution, intensified windstorms, and sunlight penetration into the patch. In the absence of indigenous flora, patches of exotic vegetation may be employed as a buffer to alleviate edge effects (Fischer et al., 2009). On the other hand, research indicates that the presence of exotics means that New Zealand indigenous birds may be better able to face food source scarcity during winters (Borkin & Parsons, 2011; Gray & van Heezik, 2016). Regardless of the size and extensiveness of patches of exotic vegetation, they can supply supplementary foraging sources when indigenous flora is not able to provide effectively.7.Conclusions: lessons for landscape architectureIndigenous purity is not likely to be achievable in the real world in urban settings. In New Zealand and other Southern Hemisphere countries, the question of indigenous vs. exotic species and landscape restoration is one of the most topical, compared to North American and European countries. This research does not advocate the planting of exotic species in urban settings, particularly those known to be weeds in a New Zealand context. The aim instead is to draw attention to potential ecological benefits of some exotic species that are already present in urbanised landscapes.Therefore, in line with efforts related to landscape restoration for increasing indigenousness in urban settings, the positive role of some exotic plants should not be ignored. A spatial study of urban Wellington undertaken in this research shows that allowing a considered proportion of indigenous to exotic flora to exist in the citycould be more practical than other alternatives such as the likely impossible task of eliminating all exotic plant species, even those that are believed to play a key role in ecological succession towards indigenous plant communities. The study also provides useful information to make an argument for balance between biodiversity conservation targets and the inevitable needs for housing and infrastructure development. However, due to the likely risk of weed and pest dispersal and the probable negative effects of some exotic plants on neighbouring indigenous habitats, exotic plants should be very cautiously maintained and/or established in urban settings. Specifically in the case of Wellington, an in-depth insight into the role of indigenous and exotic species in urban environments combined with ecological data gathered by a detailed land cover classification system could enable decision-makers to make appropriate decisions when allocating land to different purposes. For example, knowledge about ecological succession and the ability of some exotic species such as gorse and broom to enable regeneration to broadleaved indigenous hardwoods may shed light on the process of dedicating land for future housing development in Wellington. While a common belief is that gorse and broom are exotic and thereby useless, or even threatening, if managed appropriately, may be utilised as an opportunity for transition towards a range of indigenous land cover type classes. This research may be regarded as a starting point to address indigenous biodiversity in urban areas through considering opportunities that may be offered by exotic flora in order to find spatial solutions for ensuring long-term indigenous biodiversity in urbanised landscapes.中文译文利用外来植物支持城市土著生物多样性：对景观建筑的经验教训摘要有证据表明，在没有完整的自然栖息地的情况下，一些异国情调的植被可能在支持城市环境中的土著生物多样性方面发挥补偿作用。