Browsing by Subject "Ecosystem services"

Now showing 1 - 3 of 3
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    Open Access
    A fine-scale assessment of the ecosystem service-disservice dichotomy in the context of urban ecosystems affected by alien plant invasions
    (2019-10-28) Potgieter, Luke J; Gaertner, Mirijam; O’Farrell, Patrick J; Richardson, David M
    Abstract Background Natural resources within and around urban landscapes are under increasing pressure from ongoing urbanisation, and management efforts aimed at ensuring the sustainable provision of ecosystem services (ES) are an important response. Given the limited resources available for assessing urban ES in many cities, practical approaches for integrating ES in decision-making process are needed. Methods We apply remote sensing techniques (integrating LiDAR data with high-resolution multispectral imagery) and combined these with supplementary spatial data to develop a replicable approach for assessing the role of urban vegetation (including invasive alien plants) in providing ES and ecosystem disservices (EDS). We identify areas denoting potential management trade-offs based on the spatial distribution of ES and EDS using a local-scale case study in the city of Cape Town, South Africa. Situated within a global biodiversity hotspot, Cape Town must contend with widespread invasions of alien plants (especially trees and shrubs) along with complex socio-political challenges. This represents a useful system to examine the challenges in managing ES and EDS in the context of urban plant invasions. Results Areas of high ES provision (for example carbon sequestration, shade and visual amenity) are characterized by the presence of large trees. However, many of these areas also result in numerous EDS due to invasions of alien trees and shrubs – particularly along rivers, in wetlands and along the urban edge where tall alien trees have established and spread into the natural vegetation (for example increased water consumption, increased fire risk and reduced soil quality). This suggests significant trade-offs regarding the management of species and the ES and EDS they provide. Conclusions The approach applied here can be used to provide recommendations and to guide city planners and managers to fine-tune management interventions at local scales to maximise the provision of ES.
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    Open Access
    A horizon scan of future threats and opportunities for pollinators and pollination
    (2016) Brown, Mark JF; Dicks, Lynn V; Paxton, Robert J; Baldock, Katherine CR; Barron, Andrew B; Chauzat, Marie-Pierre; Freitas, Breno M; Goulson, Dave; Jepsen, Sarina; Kremen, Claire; Li, Jilian; Neumann, Peter; Pattemore, David E; Potts, Simon G; Schweiger, Oliver; Seymour, Colleen L; Stout, Jane C
    Background. Pollinators, which provide the agriculturally and ecologically essential service of pollination, are under threat at a global scale. Habitat loss and homogenisation, pesticides, parasites and pathogens, invasive species, and climate change have been identified as past and current threats to pollinators. Actions to mitigate these threats, e.g., agri-environment schemes and pesticide-use moratoriums, exist, but have largely been applied post-hoc. However, future sustainability of pollinators and the service they provide requires anticipation of potential threats and opportunities before they occur, enabling timely implementation of policy and practice to prevent, rather than mitigate, further pollinator declines. Methods. Using a horizon scanning approach we identified issues that are likely to impact pollinators, either positively or negatively, over the coming three decades. Results. Our analysis highlights six high priority, and nine secondary issues. High priorities are: (1) corporate control of global agriculture, (2) novel systemic pesticides, (3) novel RNA viruses, (4) the development of new managed pollinators, (5) more frequent heatwaves and drought under climate change, and (6) the potential positive impact of reduced chemical use on pollinators in non-agricultural settings. Discussion. While current pollinator management approaches are largely driven by mitigating past impacts, we present opportunities for pre-emptive practice, legislation, and policy to sustainably manage pollinators for future generations.
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    Local benefits of retaining natural vegetation for soil retention and hydrological services
    (2009) O'Farrell, P. J.; Donaldson, J. S.; Hoffman, M. T.
    Renosterveld is a grassy shrubland with a diverse understory of geophytes. Exceptional plant diversity and endemism, combined with considerable fragmentation due to transformation to cropland, make this vegetation type a conservation priority. The provision of formal reserves is difficult in highly fragmented landscapes. One possible way of motivating for conservation is to demonstrate the ecosystem services derived from the retention of remaining natural fragments, as a motivation for their conservation on private land. This study explored the benefits of retaining renosterveld fragments at the farm-scale based on the hydrological and soil retention services they provide. Rainfall simulations were carried out at paired sites of renosterveld and transformed renosterveld, and renosterveld and managed transformed renosterveld (requiring physical inputs). Infiltration rates, runoff volumes, sediment loads and plant species cover were recorded. This study found that infiltration was linked primarily to vegetation cover, with the highest infiltration rates experienced in renosterveld and managed transformed renosterveld dominated by alien grasses. Similarly aeolian loads and wind speeds among these three vegetation states were explored using suspension traps and hand-held anemometers. Renosterveld remnants were demonstrated to significantly reduce wind speed and aeolian load. Renosterveld provides an important service in reducing runoff, facilitating infiltration and retaining topsoil without expensive management interventions.