Urban domestic gardens (V): relationships between landcover composition,housing and landscape

The contribution to urban green space by private or domestic gardens in residential zones was investigated in the city of Sheffield, UK, as part of a wider study of the garden resource and its associated biodiversity. The attributes of 61 gardens, including patterns of landcover and vegetation cover, were explored in relation to housing characteristics and the nature of the surrounding landscape. The number of surrounding houses, and the areas of buildings and of roads were negatively correlated with garden area. The proportion of a housing parcel comprising garden increased with parcel size, although the proportion that was rear garden remained relatively constant. Garden size played an overwhelming role in determining garden composition: larger gardens supported more landcovers, contained greater extents of three-quarters of the recorded landcovers, and were more likely to contain trees taller than 2 m, vegetable patches, and composting sites. Unvegetated landcovers made greater proportional contributions as garden size declined. All categories of vegetation canopy increased with garden size, and large gardens supported disproportionately greater cover above 3 m. House age was a less significant factor determining garden landcover. Gardens of newer houses were more likely to occur towards the edge of the urban area, and older properties, that contained fewer hedges, possessed less canopy between 2–3 m. The extent and occurrence of different landcovers in gardens, and their consequences for wildlife, are considered for residential patches in urban areas. The implications for urban planners are discussed.     

Wealth and land use drive the distribution of urban green space in the tropical coastal city of Haikou,China

Urban green spaces (UGSs) provide a plethora of ecosystem services that benefit humans and wildlife within cities. UGS both promotes and is affected by overall urban ecological health, which can be measured by a wide range of indices. In this study, we investigated the distribution patterns and drivers of UGS within the tropical coastal city of Haikou, Hainan, China over the past decade using a combination of remote sensing data and field work. We interpreted Google earth images from 2010 and 2020 to determine the land cover of UGS within Urban Functional Units (UFUs). We collected socioeconomic variables to test if wealth, site age, and land use determine the proportion of UGS in the city. We found that the proportion of UGS in parks was the highest among all UFUs in 2010 and 2020. In general, UGS increased with maintenance frequency and housing price, which are proxies for the luxury effect. However, land use also played a role in UGS distribution across UFUs, especially in transportation areas, recreation and leisure districts, and residential districts. Haikou is similar to other cities in showing a positive luxury effect on the distribution of UGS. Our results highlight the key roles that parks, colleges and universities, and research institute areas have played in maintaining stable green space within Haikou over the past decade. We suggest that relatively recently implemented governmental programs to increase green space elsewhere in the city may not yet have achieved success within the time span that we analyzed.     

Accessibility to urban parks: Comparing GIS based measures in the city of Padova (Italy)

Accessibility to urban green spaces is essential for urban dwellers’ health and well-being. For planning purposes different accessibility measures and indicators have been used. Some are only based on availability, others consider distance from residences, yet others rely on gravity-based methods that consider both supply and demand. Different indicators often provide diverse and sometimes contradictory results and many issues remain in developing a comprehensive measure of accessibility, and representativity problems remain in matching indices with reality. In this study different accessibility measures have been developed and applied to the urban parks of the city of Padova, in northeastern Italy. Effectiveness and reliability of ten indicators derived from these measures, in identifying needs, inadequacies and disparities in park access have been tested at the urban unit scale. The study confirmed that multiple indicators need to be used to provide a useful planning tool for the provision of adequate and equal opportunities for open space access to the citizens. The study has also shown which indicators can be replaced by each other without losing important information.     

Hydrological behaviour of rain gardens and plant suitability: A study in the Veneto plain (north-eastern Italy) conditions

Since spring 2011 the roof of a building on the Agripolis Campus of the University of Padova (Italy) has been used as a drainage area for two rain gardens with a circular area of about 10% and 20% of the drainage area respectively. To improve soil infiltration, the topsoil was removed up to the depth of 1 m and filled with a mix of 50% sand, 25% compost and 25% of the existing topsoil. Herbaceous perennials were selected and planted to test their adaptability to different soil water conditions in the rain garden. To evaluate the capacity of each rain garden to manage stormwater runoff a simplified water balance was done, estimating actual evapotranspiration using the WUCOLS method. From autumn 2012 runoff volumes were collected just from one pitch of the roof, and directed only into the smaller rain garden that became equal to 15% of the new roof drainage area. We thus had the possibility to test the functionality of rain gardens with three different percentages of roof drainage area: 10, 15 and 20%, even if in different periods. Results are presented relating to a four-year experimental period. Regarding hydrological behaviour, the input water volumes caused a slight overflow only during a few rainfall events. Consequently, the results showed a high capacity to manage stormwater runoff and also in the smaller rain garden almost the total roof runoff volumes infiltrated into the soil. As regards plants, the results indicated that the growth is affected by their position in the rain garden, from the wettest condition in the centre to the driest at the perimeter, except for Hemerocallis hybrida that showed great adaptability in all positions. Aster novi-belgii, Echinacea purpurea, Iris pseudacorus, Molinia caerulea and Rudbeckia fulgida also showed good adaptation, even if not in all rain garden zones, with highly aesthetic results. Lythrum salicaria and Saponaria officinalis plants appeared to be unsuitable for rain gardens. The results of the experiment have shown that, in the Veneto plain environment, rain gardens with a size of 10–15% of the roof drainage area can ensure both the sustainable management of stormwater runoff and a high aesthetic functionality.     

Conservation of veteran trees within historical gardens (COVE): a case study applied to Platanus orientalis L. in central Italy

Many veteran trees characterize the landscape of Mediterranean historical parks and gardens, representing unique values from ecological, cultural, social and historical points of view. The absence of natural regeneration is one of the main limits for their conservation. The main purpose of this research was to combine theoretical reasoning and practical solutions to maintain this rich tree heritage. A protocol based on an interdisciplinary approach was developed and applied to the plane trees (Platanus spp.) within the formal garden of Villa Lante of Bagnaia (Viterbo, Italy). The COVE analysis consisted of the following four phases: i) selection of veteran tree species after gathering and comparing historical information; ii) taxonomic identification based on morphological and molecular analyses; iii) tree inventory in GIS environment; and iv) vegetative propagation by woody cuttings and micropropagation.The plane trees surveyed grow on three level terraces and significantly differ in size and phytosanitary conditions according to their topographic position. Molecular analyses indicated a genetic uniformity for the plane trees studied and their memberships to P. orientalis species. This evidence suggests that all specimens belong to the original planting dating back to 1576. All individuals showed a high susceptibility to the pathogen Ceratocystis platani even though so far there is no evidence of canker stain attack. Woody cuttings from the most vigorous individual showed 80% rooting rates. In vitro micropropagation using node culture approach provided healthy plants, maintaining the genetic fidelity respect to mother plant after three years of culture. The obtained results represent a successful example of integrated research for germplasm conservation and management of veteran trees within historical villas in Central Italy.     

Some determinants of the spatio-temporal fire cycle in a mediterranean landscape (Corsica,France)

Based on recent needs to accurately understand fire regimes and post-fire vegetation resilience at a supra-level for carbon cycle studies, this article focusses on the coupled history of fire and vegetation pattern for 40 years on a fire-prone area in central Corsica (France). This area has been submitted since the beginning of the 20^th century to land abandonment and the remaining land management has been largely controlled by frequent fires. Our objectives were to rebuild vegetation and fire maps in order to determine the factors which have driven the spatial and temporal distribution of fires on the area, what were the feed backs on the vegetation dynamics, and the long-term consequences of this inter-relationship. The results show a stable but high frequency of small fires, coupled with forest expansion over the study period. The results particularly illustrate the spatial distribution of fires according to topography and vegetation, leading to a strong contrast between areas never burnt and areas which have been burnt up to 7 times. Fires, when occuring, affect on average 9 to 12% of the S, SE and SW facing slopes (compared to only 2 to 5% for the N facing slopes), spread recurrently over ridge tops, affect all the vegetation types but reburn preferentially shrublands and grasslands. As these fire-proning parameters have also been shown to decrease the regeneration capacity of forests, this study highlights the needs in spatial studies (both in terms of fire spread and vegetation dynamic) to accurately apprehend vegetation dynamic and functionning in fire-prone areas.This revised version was published online in May 2005 with corrections to the Cover Date.     

Modeling the spatially dynamic distribution of humans in the Oregon (USA) Coast Range

A common approach to land use change analyses in multidisciplinary landscape-level studies is to delineate discrete forest and non-forest or urban and non-urban land use categories to serve as inputs into sets of integrated sub-models describing socioeconomic and ecological processes. Such discrete land use categories, however, may be inappropriate when the socioeconomic and ecological processes under study are sensitive to a range of human habitation. In this paper, we characterize the spatial dynamic distribution of humans throughout the forest landscape of western Oregon (USA). We develop an empirical model describing the spatial distribution and rate of change in historic building densities as a function of a gravity index of development pressure, existing building densities, slope, elevation, and existing land use zoning. We use the empirical model to project changes in building densities that are applied to a 1995 base map of building density to describe future spatial distributions of buildings over time. The projected building density maps serve as inputs into a multidisciplinary landscape-level analysis of socioeconomic and ecological processes in Oregon's Coast Range Mountains. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evaluating the risk of accessing green spaces in COVID-19 pandemic: A model for public urban green spaces (PUGS) in London

The pandemic caused by SARS-CoV-2 (COVID-19) at the beginning of 2020 has restricted the human population indoor with some allowance for recreation in green spaces for social interaction and daily exercise. Understanding and measuring the risk of COVID-19 infection during public urban green spaces (PUGS) visits is essential to reduce the spread of the virus and improve well-being. This study builds a data-fused risk assessment model to evaluate the risk of visiting the PUGS in London. Three parameters are used for risk evaluation: the number of new cases at the middle-layer super output area (MSOA) level, the accessibility of each public green space and the Indices of Multiple Deprivation at the lower-layer super output area (LSOA) level. The model assesses 1357 PUGS and identifies the risk in three levels, high, medium and low, according to the results of a two-step clustering analysis. The spatial variability of risk across the city is demonstrated in the evaluation. The evaluation of risk can provide a better metric to the decision-making at both the individual level, on deciding which green space to visit, and the borough level, on how to implement restricting measures on green space access.