How are we doing it?
One of the first phases of the project involves carrying out systematic aerial data collection across the three urban areas. This will gather three types of information: (i) high resolution aerial photographs, (ii) multispectral and hyperspectral data, (iii) LiDAR (light detection and ranging) data, including full waveform data. These, in combination with existing digital mapping (GIS) data, will enable us to map, classify, and assess the context of, greenspace fragments in the study area, by providing not just the two dimensional layout of fragments, but also allowing the construction of three-dimensional structure, and nature of vegetation in each fragment.
This comprehensive characterisation of greenspace fragments will provide a resource with which we can examine the relationships between the extent, form, and structural diversity of, greenspace, and urban form. Additionally, it will enable us to characterise patterns of potential connectivity and flow for organisms, people and materials.
2. Determination of biodiversity-ecosystem service relationships for a large sample of these greenspaces, across the full range of urban forms and contexts.
The catalogue of greenspace fragments generated in the first activity, will be used to make a systematic selection of fragments, capturing the variation in fragment characteristics and urban forms, upon which to base detailed on-the-ground investigations of diversity and ecosystem service delivery. A set of c. 200 fragments will be chosen and for all of these field sampling will be carried out. The field sampling will assess the diversity of: vascular plants (taxonomic and structural measures), ground and herb layer invertebrates and birds. In each of the same patches, indicators of ecosystem service provision will be measured for carbon capture and storage in soils, decomposition, runoff reduction, temperature reduction, food production, aesthetic value and psychological well-being. This detailed assessment will enable us to explore the interrelationships between different ecosystem service indicators, elements of biodiversity, and fragment
The information generated by the field assessment will be related back to the more extensive remote sensing data (see 1), enabling us to use the resulting relationships to scale up from individual fragments to combinations of fragments across the urban areas as a whole, and to explore potential effects of different urban development scenarios.
In all ecosystems, but in urban systems in particular flows of materials and organisms into and out of particular patches or fragments, may be critical to the maintenance of a function or service. At the same time, fragments may deliver their ecosystem services to the surrounding, or more distant, parts of the environment. In this part of the project we will examine the effect of selected flows between fragments on their ecosystem service provision. Specifically, we are looking at: (i) flows of people to greenspaces to receive the benefit of ecosystem services – in particular cultural services; (ii) flows to and from greenspaces of birds and the cultural services they provide; and (iii) flows of environmental regulation benefits – in particular temperature reduction – from greenspaces to the neighbouring urban environment.
These will be measured on the ground for a set of different greenspace fragments, chosen for their contrasting characteristics of biodiversity, form, or urban context. The flows require very different types of measurement: observational recording and questionnaires (people), Passive Integrated Transponder (PIT) tagging of individuals (birds), and continuous recording from environmental sensors (temperature), but in all cases we want to establish how individual fragments contribute to the wider provision of particular ecosystem services across the urban matrix.
This element of the project involves manipulation of three different elements of biodiversity or ecosystem function, to examine the effect on one or more ecosystem services. The linking theme for all three experiments is that they represent specific ‘real world’ manipulations of the urban environment of types, and scales, that relate closely to actual management and activities likely to be undertaken in urban systems. The first experimental manipulation involves altering biodiversity (taxonomic and structural) in on of the dominant forms of urban greenspace: amenity grassland. In this experiment we are planting large patches (250m2) of mown amenity grassland with a range of treatments which will increase both the species diversity of plants, and the structural diversity of the vegetation as a whole. The effects, and sustainability, of this
planting over multiple seasons will be assessed, focusing on soil characteristics, invertebrate biodiversity, and aesthetic value.
The second manipulation will examine the effect of provision of supplementary food resources on the flows of birds among greenspace fragments and the potential for cultural service provision to be enhanced by this activity. The locations for these manipulations will be identified from the results of activity 3, and quantification of changes in flow with in response to food resources will use the same PIT tagging approach.
The third manipulation involves examining the effects of the redistribution of biomass produced in individual greenspace fragments (grass cuttings, leaf litter, prunings) – i.e.
flows of biomass. The management of greenspaces produces significant quantities of biomass across an urban area, much of which is removed from where it is produced and has to be disposed of elsewhere, at considerable cost. In collaboration with our land management partners, we will test the effects of alternatives to the current practices of biomass removal on the ‘producing’ fragments, focusing on the effects of these alternatives on biodiversity, soil characteristics, water infiltration and aesthetic value.
From activities 1-4 we will have extensive structural data on urban greenspaces, information on biodiversity-ecosystem service relationships and the insights into the mechanistic links between biodiversity, flow and service delivery. We will integrate these data, relationships and understanding using a Bayesian Belief Network approach, in a spatially explicit framework. The BBN approach allows us to integrate different types of knowledge, and associated uncertainty to codify what we know about the influences of biodiversity, fragment form, and urban context, on the delivery of particular ecosystem
services. Putting this into a spatially explicit framework provides the link between the performance of individual fragments, and the integrated effects of multiple fragments, linked by flows, in providing ecosystem services across an urban area. This modelling framework will then be used to explore the scale dependence of effects of biodiversity on ecosystem service delivery and the effects of changes in urban form, and fragment composition and management on service provision – the resilience of ecosystem services.