This post was written by Jonathan Rhodes, @j_r_rhodes, on the recent paper by Masa Soga et al. on land sharing and land sparing in urban systems.
In agricultural landscapes the idea of choosing between strategies that intersperse intensive land-uses with areas set aside for biodiversity (land sparing) versus less intensive agriculture without set-asides (land sharing) to maximise biodiversity is relatively well developed (Green et al. 2005; Fischer et al. 2008; Phalan et al. 2011). The key to choosing between these strategies is understanding how the strategies modify the trade-off between agricultural production and biodiversity at landscape scales. Ultimately, for a given level of agricultural production, one strategy will tend to outperform the other in terms of biodiversity conserved based on the relative effects on the trade-offs. As such, this forms an important conceptual framework for landscape-level conservation in agricultural landscapes but, until recently, has had limited application in other systems.
One system where it naturally extends to is the urban landscape (Lin & Fuller 2013). Urban design questions predominantly revolve around how to spatially arrange urban land-uses and natural areas and, in particular, often focus on the most appropriate spatial arrangement and intensity of urban development. Lin & Fuller conceptualise urban planning decisions within the context of land-sparing and land-sharing, but there are few empirical examinations of the preferred strategy in urban landscapes.
In a recently published paper in the Journal of Applied Ecology, Soga et al. (2014) address exactly this issue and provide new insights into how we can maximise urban biodiversity based on different patterns of urban development. Their approach is focussed around quantifying the relationship between species richness/species population density and the intensity of urban development. They apply this to ground beetles and butterflies in Tokyo and then scale this up to the whole landscape under different scenarios of land sparing and land sharing. As might be predicted, land-sharing and land-sparing strategies had different impacts on biodiversity. But, the really interesting insight from this work is that these impacts depended strongly on the level of urbanisation and the taxa being considered. At high levels of urbanisation land sparing was generally the best strategy. On the other hand, at low levels of urbanisation, ground beetles continued to do better under land sparing, but butterflies, conversely, did better under land-sharing. Previous work has indicated that a land-sparing strategy may be most appropriate in cities (Sushinsky et al. 2013), but the work by Soga et al. sheds new lights on this and demonstrates that we may need to rethink this for some taxa, at least at low levels of urbanisation.
The application of the land-sparing and land-sharing concept to urban planning is generating fascinating new insights into the best spatial arrangement for urban development for biodiversity. This is a significant advance over studies applied across simple urban gradients that dominated urban ecology only a few years ago. With a growing recognition of the importance of ecosystem services for human well-being and health in cities there is considerable scope to expand the land-sharing/land-sparing concept to the provision of urban ecosystem services. The spatial structure of landscapes is an important driver ecosystem service supply and flow, but through different processes to those driving biodiversity (Bagstad et al. 2013). So, it is highly likely that strategies of land sparing and land sharing will have quite different consequences for the provision of biodiversity versus ecosystem services. Soga et al. make an important advance in our understanding of land sparing and land sparing in urban landscapes. However, I think key future challenges and research priorities lie in understanding how this translates into implications for broader ecosystem values in cities.
Papers on land-sharing/sparing recently published in Journal of Applied Ecology:
- Land sharing vs. land sparing: does the compact city reconcile urban development and biodiversity conservation?
- Surrounding habitats mediate the trade-off between land-sharing and land-sparing agriculture in the tropics – Also selected as Editor’s Choice for issue 51:5
- Modelling environmental and socio-economic trade-offs associated with land-sparing and land-sharing approaches to oil palm expansion
- FORUM: Sharing or sparing? How should we grow the world’s cities?
- Exploring the ecological constraints to multiple ecosystem service delivery and biodiversity
- Food production vs. biodiversity: comparing organic and conventional agriculture
- The spatial aggregation of organic farming in England and its underlying environmental correlates
Bagstad, K.J., Johnson, G.W., Voigt, B. & Villa, F. (2013) Spatial dynamics of ecosystem service flows: A comprehensive approach to quantifying actual services. Ecosystem Services, 4, 117-125.
Fischer, J., Brosi, B., Daily, G.C., Ehrlich, P.R., Goldman, R., Goldstein, J., Lindenmayer, D.B., Manning, A.D., Mooney, H.A., Pejchar, L., Ranganathan, J. & Tallis, H. (2008) Should agricultural policies encourage land sparing or wildlife-friendly farming? Frontiers in Ecology and the Environment, 6, 380-385.
Green, R.E., Cornell, S.J., Scharlemann, J.P.W. & Balmford, A. (2005) Farming and the fate of wild nature. Science, 307, 550-555.
Lin, B.B. & Fuller, R.A. (2013) Sharing or sparing? How should we grow the world’s cities? Journal of Applied Ecology, 50, 1161-1168.
Phalan, B., Onial, M., Balmford, A. & Green, R.E. (2011) Reconciling food production and biodiversity conservation: Land sharing and land sparing compared. Science, 333, 1289-1291.
Soga, M., Yamaura, Y., Koike, S. & Gaston, K.J. (2014) Land sharing vs. land sparing: does the compact city reconcile urban development and biodiversity conservation? Journal of Applied Ecology, 51, 1378-1386.
Sushinsky, J.R., Rhodes, J.R., Possingham, H.P., Gill, T.K. & Fuller, R.A. (2013) How should we grow cities to minimize their biodiversity impacts? Global Change Biology, 19, 401-410.