GRASSLAND ON RECLAIMED SOIL, WITH STREETS, CAR PARKS, AND BUILDINGS BUT FEW OR NO MATURE TREES
Introduction
Urban greenspace is a complex mosaic of different landscape and habitat types of many different origins. As other chapters have explained, fragments of countryside of high conservation value and even of some age can survive within the urban framework, over time undergoing shifts in the nature of the biota, but also retaining something of the original plant and animal communities. This chapter, however, is about the communities found on redeveloped land — the new spaces that are created by people with more intensive intervention. The plant and animal communities that are found on them are therefore derived from either recent natural colonization or from deliberate introduction. There is a widespread assumption among naturalists that the only species that will be found living there will be common, opportunistic, synanthropic, possibly even invasive and therefore of no great biodiversity or cultural interest. However, there can be exceptions, such as where small fragments of relatively undisturbed land still exist within the site so that a legacy of ecological history remains as nodes for colonization, or where as part of the redevelopment process, soil is imported carrying a more or less rich inoculum from other sites, or where the unusual site conditions favor an assemblage that is rare or unusual.
But even where it is true that no ‘rare’ or ‘important’ biodiversity is to be found, there can still be a lot of ecological interest for those who bother to look — surveys during the Greater Manchester Biodiversity Project led to the designation of a category of ‘grasslands of high ecological value on previously developed land’ (Richardson 2009). This chapter refers to species found in the UK, but there are clear analogues in other countries. We refer to those most obvious and most commonly seen, but in every case there is a long ‘tail’ of diversity, made up of species that are only found in a few locations. For example, a survey of 52 urban lawns in the UK (Thompson et al. 2004) found 159 species, of which 60 were recorded only once.
The existence of these newly created sites often results from government policies that aim to provide and protect a given proportion of greenspace in urban settings for the health and enjoyment of residents. Target levels of greenspace are frequently applied in contemporary town and city planning, ranging from 15—40 percent of the urban area. The latter sounds high but it is achievable in locations where high-rise tower blocks are separated by expanses of open space. This is not a new idea; one of the original aims of the first architects of high-rise livinglike Le Corbusier was to free up land that could become parkland surrounding the residences. Other major reserves of land can be road verges and spaces between roads and temporary spaces awaiting development; although the latter usually will not exist in the form of grasslands, they are more typically expanses of rubble and hard surface and colonized first by invasive shrubs like buddleia, amidst grasses and urbanized herbs, typically golden rod (Solidago spp.) and asters r (Asteraceae spp.).
However, it is often the case that the bodies that designate and create these spaces have neither the capital or operational funds, nor sufficient motivation, to make them interesting, or diverse. So alongside scattered richer areas of planting or remnant natural habitats are many mown grasslands that make up large, almost featureless plains, often scornfully referred to as ‘green deserts’. They are not devoid of life or productivity though and may be better described as urban rangelands or savannah.
Whatever the terminology, we have the unusual situation of a society investing energy and resources to create a landscape that it seems to find uninviting and not especially useful. Of course not all functions of these grasslands are dependent on our direct use. They can play important roles in climate regulation (Yost et al. 2016), biodiversity support, or rainwater absorption even if no one finds them attractive or worth studying, or even ever sets foot on them.
Mostly, though, the grasslands are intended by town planners to be there for multiple uses and in principle they are primarily intended for recreation and ‘amenity’. As with any other animal, in practice the extent and patterns of human activity on these sites depend on how welcoming they feel and how successfully they meet our needs, which in turn depends on aspects such as shelter, seating, accessibility, and location including proximity to homes or workplaces, exposure, height of grass, and drainage. Such aspects together affect how comfortable it is to settle as does the density of off-putting factors, such as large dogs and territoriality and aggression among human social groups. In some countries the grasslands may contain other species that are threatening, such as the snakes and the lethal spiders that can be found in urban grassland in Australia. In such locations, strictures to ‘keep off the grass’carry additional weight.
On the other hand, where the site factors are appropriate, some grasslands receive high regular use by many people particularly in good weather, and especially for children’s games or sport or for lunchtime relaxation by office workers. Some sites are dominated by uses that are not always compatible with other people — team sports, golf practice, and dog excreta. Other sites are rarely visited by anyone (although if they are not too overlooked this may give them a higher value for activities that need a degree of privacy: not all of which are criminal).
