Fragmentation has well-known serious consequences for biodiversity, but what about consequences for people? Most landscapes that are heavily fragmented, like agricultural or urban areas, are not only managed for biodiversity, but also to provide benefits, or ecosystem services, to people. What are the effects of fragmentation on things like pollination, pest regulation, water purification, or even recreation? This is a critical question if we want to manage human-dominated landscapes for both biodiversity and ecosystem services.
In a recent study, I, along with a number of co-authors, tried to answer this question conceptually. The core of our framework is that service provision depends on supply, demand, and flow. First, an ecosystem has to be able to generate or supply a potential benefit for people. This supply often depends on biodiversity. Second, there has to be demand by people for this service. Finally, people have to interact with the ecosystem to gain the benefit. This final step is what we call an ecosystem service flow. These flows depend on the movement of organisms, matter, and people across landscapes.
As an example, think about a local park where people go bird-watching. This recreation service depends on the park’s capacity to support a diverse bird community (supply), people that enjoy birds and like getting up early (demand), but also on the ability of people to access the park (flow). Similarly, pollination depends on natural habitat that can support pollinators (supply), crops that depend on pollination (demand), and the ability of pollinators to access these fields (flow).
We argued that fragmentation can impact service flows both negatively and positively. Roads, pipelines, and land clearing can impair the ability of organisms to move across landscapes, with potential negative effects on biodiversity and service supply. However, fragmentation can also intersperse people and ecosystems and put them in closer proximity to each other, potentially increasing flows. These contrasting effects mean that the consequences of fragmentation are likely to be very diverse. We therefore need to think carefully about how landscape changes impact the flows of multiple ecosystem services.
A critical next step is to test our conceptual framework. As part of a larger research project in the agricultural landscapes in southern Quebec, I found that the size and isolation of forest fragments affect their ability to supply a number of ecosystem services, including pest regulation. In turn, field sizes and hedgerows influenced pest regulation flows, altering the ability of insect pests and predators to move across the landscape. Currently, I’m working in Brisbane, Australia, to understand how urban landscape structure affects the supply of carbon storage, flood regulation, and microclimate regulation and the flow of these services to urban residents.
While scientific understanding of service flows is critical, equally important is integrating this knowledge into landscape-scale decision-making tools and mechanisms. Only in this way can we create truly multi-functional landscapes that remain connected to support people and biodiversity.
Mitchell, M.G.E. 2016. Fragmentation and ecosystem services: connecting a fragmented landscape with human wellbeing. Decision Point 94: 10-11.
Mitchell, M.G.E., E. M. Bennett, and A. Gonzalez. 2014. Forest fragments modulate the provision of multiple ecosystem services. Journal of Applied Ecology 51(4): 909-918.
Mitchell, M.G.E., E. M. Bennett, and A. Gonzalez. 2014. Agricultural landscape structure affects arthropod diversity and arthropod-derived ecosystem services. Agriculture, Ecosystems & Environment 192: 144-151.
Mitchell, M.G.E., E. M. Bennett, A. Gonzalez, M. J. Lechowicz, J. M. Rhemtulla, J. A. Cardille, K. Vanderheyden, G. Poirier-Ghys, D. Renard, S. Delmotte, C. H. Albert, B. Rayfield, M. Dumitru, H. H. Huang, M. Larouche, K. N. Liss, D. Y. Maguire, K. T. Martins, M. Terrado, C. Ziter, L. Taliana, and K. Dancose. 2015. The Montérégie Connection: linking landscapes, biodiversity, and ecosystem services to improve decision making. Ecology and Society 20(4): art15.
Mitchell, M.G.E., A. F. Suarez-Castro, M. Martinez-Harms, M. Maron, C. A. McAlpine, K. J. Gaston, K. Johansen, and J. Rhodes. 2015. Reframing landscape fragmentation’s effects on ecosystem services. Trends in Ecology and Evolution 30(4): 190-198.