Urban Parklands Research Articles

Children’s Guerrilla Play and Dirt Jumps: Parkland as Contested Space During the Covid-19 Pandemic in Australia

AbstractIn 2020-21 the Victorian state government in Australia imposed 262 days of sustained lockdown on Melbourne’s population in a bid to contain the COVID pandemic. These lockdowns, among the longest in the world, affected young people especially. Children were subjected to months of curfews, home schooling using digital platforms and severe travel. Nonetheless some children engaged repeatedly in autonomous and well co-ordinated efforts to construct dirt jumps and ride their bikes in urban public parklands in eastern Melbourne. This article is mindful of a long tradition of scholarly work tracing the ways young people have used public space, and contested ‘adultist’ representations of them and regulations affecting the use of public space. We address three questions: Why and how did children design, construct and use dirt bike jumps during the COVID pandemic in public parklands? How did Victorian local councils and others like police, older residents and mainstream media respond to children’s construction of DIY dirt jumps? How were these spontaneous DIY dirt jumps understood by Victorian local councils? Adopting a composite case study method and employing a relational perspective, we draw on images, participant observation, field notes, documents and webpage analysis to answer the research questions. We document how children used urban parklands to hang out, to onstruct and use bike jumps during the lockdowns. We show how they challenged adult representations of themselves and public space which depicted their bike riding and the jump making as anti-social and illegal. Meanwhile local governments continued through the COVID-19 pandemic to proclaim the value of ‘youth participation.’ When that youth participation involved young people initiating and managing projects themselves, their conduct was deemed unlawful as councils continued denying them any meaningful opportunities to exercise autonomy, or have say in important policy decisions. In the final section of the article say why providing insider accounts of what happens is useful for good policy-making and professional practice.

Electronic sun journal as an evaluation tool for measuring sunflecks while walking through urban forests

Fluctuations in direct sunlight intensities (or sunflecks) are experienced in urban forest parklands. A novel application of an electronic sun journal (ESJ) was developed providing accessible, objective detection and analysis of sunflecks sampled at 50 Hz while walking through urban parkland forests in Toowoomba (27.57°S 151.95°E), Australia. A total of 654 sunflecks were detected during 12 walks. Sunfleck durations (SFD) ranged from 0.02 s to 102.5 s, with a median of 0.10 s and interquartile range of 0.04-0.28 s. The sunfleck intervals (SFI) ranged from 0.02 s to 115 s, with a median of 0.16 s and interquartile range of 0.06-0.62 s. Of the 10,983 sunfleck clusters, approximately 90% included two or four sunflecks per second, with the highest frequency cluster reaching eight. The distribution of the sunfleck clusters changed with different sun angles and azimuth as the sunlight passed through different parts of urban parklands. The developed method with the ESJ may be employed in the evaluation of sunfleck durations, intervals and clusters at eye level in other urban forest environments, adding to the developing interest as greenspaces play an increasing role in urban studies.

Co-occurrence of macroplastics, microplastics, and legacy and emerging plasticisers in UK soils

Despite a theoretical link between plastic and plasticiser occurrence in the terrestrial environment, there are few empirical studies of the relationship between these contaminants in soils. We carried out a field study to assess the co-occurrence of plastic waste, and legacy and emerging plasticisers in UK soils (n = 19) from various land uses (woodlands, urban roadsides, urban parklands, landfill-associated). Surface plastics and soil microplastics were quantified and characterised using ATR-FTIR and μ-FTIR. Eight legacy (phthalate) and three emerging (adipate, citrate, trimellitate) plasticisers were quantified using GC–MS. Surface plastics were found at higher prevalence at landfill-associated and urban roadside sites, with levels significantly (2 orders of magnitude) greater than in woodlands. Microplastics were detected in landfill-associated (mean 12.3 particles g−1 dw), urban roadside (17.3 particles g−1 dw) and urban parkland (15.7 particles g−1 dw) soils, but not in woodland soils. The most commonly detected polymers were polyethene, polypropene and polystyrene. Mean ∑plasticiser concentration in urban roadside soils (3111 ng g−1 dw) was significantly higher than in woodlands (134 ng g−1 dw). No significant difference was found between landfill-associated (318 ng g−1 dw) and urban parkland (193 ng g−1 dw) soils and woodlands. Di-n-butyl phthalate (94.7% detection frequency) and the emerging plasticiser trioctyl trimellitate (89.5%) were the most commonly detected plasticisers, with diethylhexyl phthalate (493 ng g−1 dw) and di-iso-decyl phthalate (96.7 ng g−1 dw) present at the highest concentrations. ∑plasticiser concentrations were significantly correlated with surface plastic (R2 = 0.23), but not with soil microplastic concentrations. Whilst plastic litter seems a fundamental source of plasticisers in soils, mechanisms such as airborne transport from source areas may be as important. Based on the data from this study, phthalates remain the dominant plasticisers in soils, but emerging plasticisers are already widespread, as reflected by their presence in all land uses studied.

Analysis of the Cooling and Humidification Effect of Multi-Layered Vegetation Communities in Urban Parks and Its Impact

As urbanization continues to accelerate, the urban heat island effects have become one of the most important issues affecting the urban environment and people’s living experience. Numerous studies have shown that urban parks and green spaces can effectively alleviate the problem of the urban heat island effect and provide cooling and humidifying effects. Vegetation communities are a fundamental part of urban parklands, and multi-layered vegetation communities are considered to have better cooling and humidifying effects. Previous studies have focused on comparative analyses between different cover types of vegetation communities but have not explored the differences in the cooling and humidifying effects of multi-layered vegetation communities of the same cover type. Therefore, the Olympic Forest Park in Beijing was selected as the subject of this study, and multi-layered vegetation-covered (tree-shrub-grass) with different degrees of densities and uncovered squares were selected for the control and comparison. The cooling and humidifying effects of multi-layered vegetation communities with different canopy densities at different times of the day through field measurements were studied, and the influencing factors for this were analyzed. The results show that the tree cover is the core factor affecting temperature; the degree of the canopy density of multi-layered vegetation communities is significantly and positively correlated with the intensity of cooling and humidification, and the cooling and humidifying effect of multi-layered vegetation communities increases as the degree of canopy density increases. The results of this study can provide some references for the planning and design of urban parks and green spaces.

Landscape features and forest maturity promote the occurrence of macroinvertebrates specialized for seepage springs in urban forests in Washington, DC

Abstract The hypotelminorheic is a groundwater‐fed shallow subterranean habitat, occurring a few metres below the surface and emerging at a seepage spring. Little is known about the habitat requirements for the amphipods and isopods that live there, and forest quality and other surface parameters have been largely unexplored. Urban parks, encompassing protected lands from ballfields to forests, are not necessarily secure sites, because of non‐compatible uses and changing park boundaries. Almost all records for this fauna in the study area are in parks. Using data from sampling in parklands of south‐east Washington, DC, exploratory analyses were conducted at two spatial scales – the seeps and pervious land patches surrounded by impervious surfaces (which range from 0.59 to 231 ha). Habitat quality, fragmentation and geological variables were calculated, and exploratory logistic regression models were fitted to predict occupancy. Hypotelminorheic macroinvertebrates were found at 66 of 207 seeps and 15 of 27 patches. Five species were collected, three of which were uncommon. Only patches containing three or more seeps and >7.6 ha were inhabited. Occurrence of one or more species in seeps was associated with distance inside the forest, taller tree canopy, elevation and geological formation. There is a threshold amount of habitat below which a population can no longer exist. Few patches of forest remain that are sufficiently large for habitation, and conservation actions should prioritize forested patches with three or more seeps. In addition, the development of forested corridors to enhance connectivity among populations, education of the public about the value of the hypotelminorheic, and development of field methods to detect habitats is recommended. Urban parklands can be important reservoirs for species of conservation concern.

After the Contagion. Ghost City Centres: Closed “Smart” or Open Greener?

This paper has three main objectives. It traces the “closed” urban model of city development, critiques it at length, showing how it has led to an unsustainable dead-end, represented in post-Covid-19 “ghost town” status for many central cities, and proposes a new “open” model of city design. This is avowedly an unsegregated and non-segmented utilisation of now often abandoned city-centre space in “open” forms favouring urban prairie, or more formalised urban parklands, interspersed with so-called “agritecture” in redundant high-rise buildings, shopping malls and parking lots. It favours sustainable theme-park models of family entertainment “experiences” all supported by sustainable hospitality, integrated mixed land uses and sustainable transportation. Consideration is given to likely financial resource issues but the dearth of current commercial investment opportunities from the old carbonised urban model, alongside public policy and consumer support for urban greening, are concluded to form a propitious post-coronavirus context for furthering the vision.

RETRACTED ARTICLE: Foliar nitrogen characteristics of two tropical tree species along urban roads and parklands

Statement of Retraction Retraction: Foliar nitrogen characteristics of two tropical tree species along urban roads and parklands We, the Editor and Publisher of Arboricultural Journal, have retracted the following article: Lai Fern Ow & Samantha Ng (2020) Foliar nitrogen characteristics of two tropical tree species along urban roads and parklands, Arboricultural Journal, DOI: 10.1080/03071375.2020.1746540 It has come to our attention that this paper is also published in the journal Urban Ecosystems, <Vol 23. 985–993 (2020). https://doi.org/10.1007/s11252-020-00960-0 > and therefore cannot be deemed an original contribution. We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as “Retracted”.

Foliar nitrogen characteristics of two tropical tree species along urban roads and parklands

Citywide tree planting in urban cities is occurring rapidly because of the benefits urban vegetation provide to the environment. Nutrient cycling in tropical urban ecosystems is relatively unknown. Nitrogen utilisation in urban and rural conditions can vary substantially hence foliar N characteristics of two common tree species grown in the tropics was compared between urban roads and parkland sites. The study was carried out in the tropical island state of Singapore situated 1° north of the equator. Foliar sampling of nitrate reductase, %C, %N, δ13C and δ13N in two tree species grown along urban roads and parklands were evaluated. Foliage sampled along roads were depleted of δ15N compared to parkland foliage. Significantly higher levels of δ13C, nitrate reductase activity (NRA), %C and %N were found in the northern and southern Parklands. Samanea saman, and Khaya senegalensis showed significantly greater ability to assimilate nitrate at the park sites, measured through NRA. There were no significant differences in foliar N and C characteristics between tree species. Significant variation in foliar N and C concentrations were only observed between regions and at park and road sites. The isotopic and %N data suggested greater N availability and higher available nitrate at park sites as a result of variable site histories. These previous land use, land cover change may have accumulated organic matter in the rhizosphere primarily in the stable form of humus alongside that of biological nitrogen fixation. N cycling in urban systems and associated physiological changes in vegetation is critical as these may have implications for carbon sequestration, while N retention or export can impact on water quality in urban environments.

Understanding and Analysing the Urban Heat Island (UHI) Effect in Micro-Scale

The shortage of vegetation cover alongside urban structures and land hardscape in cities causes an artificial temperature increase in urban environments known as the urban heat island (UHI) effect. The artificial heat stress in cities has a particular threat for usability and health-safety of outdoor living in public space. Australia may face a likely 3.8°C increase in surface temperature by 2090. Such an increase in temperature will have a severe impact on regional and local climate systems, natural ecosystems, and human life in cities. This paper aims to determine the patterns of the UHI effect in micro-scale of Adelaide metropolitan area, South Australia. The urban near-surface temperature profile of Adelaide was measured along a linear east-west cross-section of the metropolitan area via mobile traverse method between 26 July 2013 and 15 August 2013. Results indicate that the while the maximum UHI effect occurs at midnight in the central business district (CBD) area in Adelaide, the afternoon urban warmth has more temperature variations (point-to-point variation), especially during the late afternoon when local air temperature is normally in its peak. Thus, critical measurement of heat-health consequences of the UHI effect need to be focused on the afternoon heat stress conditions in UHIs rather than the commonly known night time phenomenon. This mobile traverse urban heat study of Adelaide supports the hypothesis that the UHI effect varies in the built environment during daily cycles and within short distances. Classical UHI measurements are commonly performed during the night – when the urban-rural temperature differences are at their maximum. Thus, they fall short in addressing the issue of excess heat stress on human participants. However, having thermally comfortable urban microclimates is a fundamental characteristic of healthy and vibrant public spaces. Therefore, urban planning professionals and decision makers are required to consider diurnal heat stress alongside nocturnal urban heat islands in planning healthy cities. The results of this article show that the diurnal heat stress varies in the built environment during daily cycles and within short distances. This study confirms that the maximum urban heat stress occurs during late afternoon when both overall temperature and daily urban warmth are at their peak. Literature indicates that diurnal heat stress peaks in hard-landscapes urban settings while it may decrease in urban parklands and near water bodies. Therefore, urban greenery and surface water can assist achieving more liveable and healthy urban environments (generalisation requires further research). A better understanding of daily urban warmth variations in cities assists urban policy making and public life management in the context of climate change.

Modelling of the Radiant Heat Flux and Rate of Spread of Wildfire within the Urban Environment

One approach to increase community resilience to wildfire impacts is the enhancement of residential construction standards in an effort to provide protective shelters for families within their own homes. Current wildfire models reviewed in this study assume fire growth is unrestricted by vegetation fuel bed geometry; the head fire has attained a quasi-steady rate of spread; and the shielding effects of urban development are ignored. As a result, radiant heat flux may be significantly overestimated for small vegetation fires in road reserves, urban parklands, and similar scenarios. This paper proposes two new models to address this issue, and utilises two case studies for comparison against existing approaches. The findings are significant as this is the first study to analyse these factors from a fire engineering perspective, and to demonstrate that the use of landscape scale or siege wildfire models may not be appropriate within the urban context. The development of enhanced wildfire models will have a significant impact on town planning and construction practices in areas prone to wildfires, as well as firefighting suppression efforts when these events occur.

The value of scattered trees for wildlife: Contrasting effects of landscape context and tree size

AbstractAimThe biodiversity value of scattered trees in modified landscapes is often overlooked in planning and conservation decisions. We conducted a multitaxa study to determine how wildlife abundance, species richness and community composition at individual trees are affected by (1) the landscape context in which trees are located; and (2) the size of trees.LocationCanberra, south‐eastern Australia.MethodsTrunk arthropod, bat and bird surveys were undertaken over 3 years (2012–2014) at 72 trees of three sizes (small (20–50 cm DBH), medium (51–80 cm), large (≥80 cm)) located in four landscape contexts (reserves, pasture, urban parklands, urban built‐up areas).ResultsLandscape context affected all taxa surveyed. Trunk arthropod communities differed between trees in urban built‐up areas and reserves. Bat activity and richness were significantly reduced at trees in urban built‐up areas suggesting that echolocating bats may be disturbed by high levels of urbanization. Bird abundance and richness were highest at trees located in modified landscapes, highlighting the value of scattered trees for birds. Bird communities also differed between non‐urban and urban trees. Tree size had a significant effect on birds but did not affect trunk arthropods and bats. Large trees supported higher bird abundance, richness and more unique species compared to medium and small trees.Main conclusionsScattered trees support a diversity of wildlife. However, landscape context and tree size affected wildlife in contrasting ways. Land management strategies are needed to collectively account for responses exhibited by multiple taxa at varying spatial scales. We recommend that the retention and perpetuation of scattered trees in modified landscapes should be prioritized, hereby providing crucial habitat benefits to a multitude of taxa.

Участь деревних інвазійних видів рослин у формуванні насаджень паркової зони міста Дніпро

A comparative analysis of the green plantation state in Volodya Dubinin Park and Pisarzhevsky Park is carried out. The species composition, age structure and health status of trees have been studied. The taxonomic diversity of of the Dibinin Park is rather poor and has 27 species and 2 cultivars. The Conifers are not presented. Dominating species are Acer platanoides L, Populus deltoides Marsh.and also invasive species Morus alba L., Acer negundo L., Robinia pseudoacacia L. Dendroflora of Pisarzhevsky Park is more multifarious and totals 40 species and 1 cultivar. There are many conifers. Dominating species are Pinus nigra Arnold. The number of invasive species is small. Almost half of all trees in Volodya Dubinin Park are young plants. However, such high indicator is provided by numerous self-sown plants of Morus alba, Acer negundo, Acer platanoides and Sambucus nigra L. The middle-aged, senescent and old specimens prevail in Pisarzhevsky Park. Health condition of the tree majority in both parks is right enough. It is revealed that 18% of trees in Volodya Dubinin Park and 21% in Pisarzhevsky Park are defective. Trees damaged by horse-chestnut leaf miner, Dutch elm disease and polypore are found. The order of actions for the recovery of urban parklands is determined. For improvement and recovery of both parks it is necessary to fulfill territory clearing, remove defective and dead trees, conduct sanitary and rejuvenating pruning. To replace low-value and invasive tree species it is recommended a range of new resistant ornamental types including exotic and indigenous. Keywords: urban parkland , dendroflora, monitoring, species structure, age, health, renovation

Stories, Shrines, and Symbols: Recognizing Psycho-Social-Spiritual Benefits of Urban Parks and Natural Areas

Urban parklands are biological and social resources. While there is a growing recognition that park users interact with these resources to promote well-being, the diversity of these practices and benefits is not fully appreciated. Here we draw upon data from a social assessment of 40 New York City (NYC) parks spanning 11,200 acres and we focus on psycho-social-spiritual benefits that are co-produced by park users and parks. Our methods include interviews (n = 1,680), field observations, and photo documentation. Given our large and diverse sample, the data show that psycho-social-spiritual engagement with parkland is important across geographic, sociocultural, religious, and other identities throughout NYC. While specific practices may be culturally differentiated, we find that urban parks support psycho-social-spiritual well-being for a wide range of people who engage in practices that reflect personal desires to connect with nature and a larger reality, as well as via a broader set of practices focused on connecting with self and with others. Our approach is novel because it integrates data on park users from interviews, observations of activities, and material evidence of prior use of parklands. We describe our findings and present a typology of psycho-social-spiritual engagement with natural areas in NYC parklands. This study advances theoretical understandings of the psycho-social-spiritual as it manifests within the dynamic relationship between humans and the urban environment, raises questions about the implications of these findings for the management of social-ecological systems, and suggests future research that delves into the practices of specific cultural and park user groups.

Comparing Three Approaches of Evapotranspiration Estimation in Mixed Urban Vegetation: Field-Based, Remote Sensing-Based and Observational-Based Methods

Despite being the driest inhabited continent, Australia has one of the highest per capita water consumptions in the world. In addition, instead of having fit-for-purpose water supplies (using different qualities of water for different applications), highly treated drinking water is used for nearly all of Australia’s urban water supply needs, including landscape irrigation. The water requirement of urban landscapes, particularly urban parklands, is of growing concern. The estimation of evapotranspiration (ET) and subsequently plant water requirements in urban vegetation needs to consider the heterogeneity of plants, soils, water, and climate characteristics. This research contributes to a broader effort to establish sustainable irrigation practices within the Adelaide Parklands in Adelaide, South Australia. In this paper, two practical ET estimation approaches are compared to a detailed Soil Water Balance (SWB) analysis over a one year period. One approach is the Water Use Classification of Landscape Plants (WUCOLS) method, which is based on expert opinion on the water needs of different classes of landscape plants. The other is a remote sensing approach based on the Enhanced Vegetation Index (EVI) from Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on the Terra satellite. Both methods require knowledge of reference ET calculated from meteorological data. The SWB determined that plants consumed 1084 mm·yr−1 of water in ET with an additional 16% lost to drainage past the root zone, an amount sufficient to keep salts from accumulating in the root zone. ET by MODIS EVI was 1088 mm·yr−1, very close to the SWB estimate, while WUCOLS estimated the total water requirement at only 802 mm·yr−1, 26% lower than the SWB estimate and 37% lower than the amount actually added including the drainage fraction. Individual monthly ET by MODIS was not accurate, but these errors were cancelled out to give good agreement on an annual time step. We conclude that the MODIS EVI method can provide accurate estimates of urban water requirements in mixed landscapes large enough to be sampled by MODIS imagery with 250-m resolution such as parklands and golf courses.

Effects of entrance size, tree size and landscape context on nest box occupancy: Considerations for management and biodiversity offsets

The effectiveness of nest boxes as a management and biodiversity offset tool remains equivocal and controversial. Improving nest box programs requires urgent empirical research to identify the spatial factors that affect occupancy outcomes. Understanding which fine, local and landscape-level attributes influence nest box selection by wildlife can assist practitioners in refining nest box designs and placement in the field. We asked: Does entrance size, tree size and landscape context affect nest box occupancy? We monitored 144 nest boxes with six different entrance sizes (20, 35, 55, 75, 95 and 115mm diameter), secured to individual trees of three sizes (small 20–50cm DBH, medium 51–80cm and large >80cm) situated in four different landscape contexts with varying degrees of modification (reserves, pasture, urban parklands and urban built-up areas). We found that six common native and exotic species accounted for 89% of nest box occupancies. Entrance size had a significant effect on overall occupancy. Nest boxes with larger entrance sizes (115, 95, 75 and 55mm) were occupied more (⩾77% of nest boxes occupied) than nest boxes with smaller entrance sizes (35 and 20mm; ⩽45% of nest boxes occupied). Tree size and landscape context had no significant effect on overall occupancy. However, multinomial analysis revealed that entrance size and landscape context affected occupancy by common fauna (i.e. species that occupied ⩾5% of nest boxes). Nest boxes with small (20 and 35mm), intermediate (55 and 75mm) and large (95 and 115mm) entrance sizes were predominately occupied by the European honey bee Apis mellifera, common exotic (e.g. common myna Acridotheres tristis) and native birds (e.g. eastern rosella Platycercus eximius), and the common brushtail possum Trichosurus vulpecula, respectively. Nest boxes in reserves and pasture had near equal occupancy by common fauna while nest boxes in urban parklands and urban built-up areas were predominately occupied by the common brushtail possum and the European honey bee. Establishing nest boxes with different entrance sizes could maximise occupancy by a variety of common hollow-nesting species. Targeting occupancy by some species requires consideration of landscape context but not tree size. Nest boxes were predominately occupied by a few common native and exotic species, suggesting that nest boxes may not be highly effective management and biodiversity offset tools for rare and threatened taxa in modified landscapes. Management policies and practices aimed at avoiding the loss of large, hollow-bearing trees must be prioritised.

THE COOLING EFFECT OF A MEDIUM SIZED PARK ON AN URBAN ENVIRONMENT

The Urban Heat Island (UHI) effect can best be described as an increase in the temperature of urban areas relative to their surroundings. This effect can exceed 5oC in places. This study investigates how vegetation, in particular urban parklands, can be used to reduce the intensity of the UHI effect. To achieve this, the study uses a ground based approach relying on high spatial and temporal resolution temperature measurements using both a hand-held weather meter and a hand-held thermal laser-gun. The study focusses on one medium sized park in Melbourne, Australia and samples air temperatures (at 5 cm and 1.5 m above the ground) and land surface temperature profiles six times a day over one month starting within the park and extending to approximately 1 km outside of the park. The study shows that the park has a significant cooling effect for a distance of up to 860 m from its boundaries and that this is most significant in the early morning. The study also shows that land surface temperatures are more sensitive to park cooling effects than are air temperatures.

Enriching small trees with artificial nest boxes cannot mimic the value of large trees for hollow‐nesting birds

Large trees support unique habitat structures (e.g. hollows) that form over centuries and cannot be provided by small trees. Large trees are also declining in human‐modified landscapes worldwide. One restoration strategy gaining popularity involves adding nest boxes to smaller trees to replicate natural hollows. However, limited empirical research has tested how hollow‐nesting fauna responds to the presence of nest boxes. We asked: can the addition of nest boxes increase tree visitation by hollow‐nesting birds? We conducted a before‐after control‐impact (BACI) experiment using 144 nest boxes and 96 sample trees comprised of three sizes (small [20–50 cm dbh], medium [51–80 cm], and large [&gt;80 cm]) and located in four landscape contexts (reserves, pasture, urban parklands, and urban built‐up areas). We recorded a significant increase in hollow‐nesting bird abundance and richness at large trees after nest box additions. However, the same response was not observed at medium, small, or control trees. We also recorded nonsignificant increases in hollow‐nesting bird abundance and richness at trees in modified landscapes after nest box additions compared to trees in reserves and control trees. Our results suggest that adding nest boxes to smaller‐sized trees may not attract hollow‐nesting birds. Therefore, nest box management strategies may require re‐evaluation as it is often assumed that hollow supplementation will attract hollow‐using fauna and sufficiently ameliorate the loss of large, hollow‐bearing trees. We advocate that large tree retention remains crucial and should be prioritized. Large trees could be effective target structures for habitat restoration, especially in modified landscapes.

Single large or several small? Applying biogeographic principles to tree-level conservation and biodiversity offsets

Land development contributes to the clearance of large trees that are sometimes offset with many smaller trees as compensatory wildlife habitat. But are many smaller trees a valid biodiversity offset for the loss of a single large tree? To answer this question, we tested predictions underpinned by island biogeography theory. Targeting birds, we investigated size and landscape context effects at 72 trees of three sizes (small, medium, and large) located in four landscape contexts (reserves, pasture, urban parklands, and urban built-up areas). Significant positive relationships occurred between tree basal area and bird abundance and species richness in all landscape contexts. SLOSS (single large or several small) analysis revealed that in modified landscapes, several small and medium trees supported an equivalent number of individuals and species as a single large tree, but the same pattern was weaker in reserves. Extrapolated rarefaction curves revealed that in reserves and urban built-up areas, many small or medium trees accumulated the same number or more species than large trees. However, in pasture and urban parklands, many small or medium trees accumulated fewer species than large trees. Overall, 29% of bird species were recorded only at large trees, highlighting that many smaller trees will not be suitable habitat compensation for all species. Complementary approaches to biodiversity offsets are needed, balancing large tree preservation and revegetation. Response patterns for birds at trees conformed to some biogeographic predictions (species–area relationship), but not others (habitat–isolation relationship), underscoring the need for novel conceptual frameworks for habitat structures in modified landscapes.

Urban greening: environmentalism or marketable aesthetics

In recent decades, urban greening has been conceptualized, and subsequently marketed, as a way of making cities more sustainable. Urban greening has been actualized in large global cities, regional centers, and also in many cities in the Global South, where it has been touted as a potential solution to the urban heat island (UHI) effect and as a way of reducing carbon dioxide (CO2) emissions. This involves planting street trees and installing curbside gardens, bioswales, green walls, green roofs, and the redevelopment of former industrial zones into urban parklands. This paper questions the assumption that this “greening” of the city must necessarily lead to positive environmental impacts. While such infrastructure itself might be constructed with environmental principles in mind, wider questions concerning the production of such landscapes, and the consumption-orientated lifestyles of those who inhabit these urban landscapes, are seldom considered. Moreover, green aesthetics and environmental sustainability are not always as mutually inclusive as the concepts might suggest, as aesthetics are often a dominating influence in the process of planning green urban environments. This review reorients the focus on the way in which the UHI effect and CO2 emissions have been framed by utilizing Foucault's (1980) “regimes of truth,” where environmental issues are contextualized within the “colonised lifeworld” of free-market forces. This review suggests that for sustainability to be achieved in urban contexts, the process of urban greening must move beyond quick techno-fixes through engagement in the co-production of knowledge.

Reprint of “Unruly grasses: Affective attunements in the ecological restoration of urban native grasslands in Australia”

This paper explores affect as an ’angle of approach’ for re/considering the work of ecological restoration in urban spaces. My focus is on the more-than-human affective dimensions of the reintroduction of native grasses in Melbourne’s (Australia) urban parklands. Sara Ahmed suggests that ’affect is what sticks or sustains or preserves the connection between ideas, values and objects’ (2010, 29), and here I extend this notion to think about the restoration of grasslands not as primarily material transformations (to which we might react), but as the recomposition of the ’ideas, values and objects’ that constitute urban park naturecultures. The paper highlights the role of affective relations in the inheritance of landscapes that do not attract widespread positive affection. It employs Sara Ahmed’s concept of the affect alien as a figure of nonconformity, to uncover how the affective resonances of grasslands might open new possibilities for attuning to the complex and multiple naturecultures of postcolonial lands.