In the land sparing and sharing debate, the question is often how food and wildlife can find space around each other. In today’s blog Tom Finch, Senior Conservation Scientist, discusses his latest paper which considers other factors. This new research reviews what’s best for protecting against global warming, recreation and reducing pollution, whilst still growing food and protecting nature.
We are placing land under increasing pressure to meet food demands, to absorb climate-warming gases, to slow and clean water, and to provide escapes from modern life. At the same time, wild nature needs land too. Reconciling these often-competing demands presents a major societal challenge.
One lens through which to view this challenge is the land sharing-sparing continuum. At its simplest, this is a thought experiment which asks whether a particular quantity of food would be better delivered by integrating production and conservation across all available land (sharing), or by separating production and conservation into specialised areas (sparing).
Most previous studies suggest that the costs of agriculture to biodiversity would be minimised by a land-sparing strategy, because of the fundamental importance of intact natural habitat. This highlights the value of high-yielding agriculture which – especially if combined with demand-side measures such as waste reduction – can help limit the area of land needed to feed the world. Results are more nuanced in Europe, where ‘traditional’ farmland supports distinct and important wildlife. Here, high-yield farmland and spared habitat alone are insufficient; some shared farmland, targeted at sensitive farmland-dependent species, is also needed.
An outstanding question is how these alternative strategies stack up for other outcomes like global warming potential, diffuse pollution and outdoor recreation.
For this study, we designed a suite of spatial scenarios for The Fens and Salisbury Plain, all delivering 2015 levels of food production through a range of alternative strategies (Fig. 1). Towards extreme sparing, we concentrated food production into a smaller area of increasingly arable-dominated land, therefore freeing up other land to be restored (in 1-km units) to semi-natural habitat.
Towards extreme sharing, we expanded agriculture into the currently unfarmed areas, therefore allowing the farmed area to become increasingly less arable-dominated (by introducing small pockets of woodland and grassland). Under the mixed ‘three compartment sparing’ strategy, the concentration of food production into a smaller area was used to make space both to restore semi-natural habitat and to create pockets of mixed farmland.
Figure 1. Illustrative maps showing sharing and sparing scenarios for The Fens (top) and Salisbury Plain (bottom). BaU = 2015 land cover.
For land sparing scenarios, we also explored 5 alternative regional plans defining which habitat should be restored where (either fen or wet grassland in The Fens, or chalk grassland or woodland in Salisbury Plain). These included ‘least cost’ (restoring the least productive farmland first) and ‘adjacent’ (expanding existing semi-natural habitats), and several scenarios intended to protect regionally-important features such as deep peat, groundwater or chalk streams.
For each scenario, we then predicted the consequences for breeding birds, global warming potential, nitrogen and phosphorus export, and nature-based recreation.
The multiple benefits of spared land
Our headline finding is that, whilst some outcomes improved under land sharing, most saw the strongest improvement under a sparing strategy (Fig. 2), where yields on farmed land are increased and more land is restored to semi-natural habitats. Importantly, not all sparing strategies performed equally well, and some made things worse:
Figure 2. The average response score, summarised across all 5 outcomes, tended to increase towards the sparing end of the strategy spectrum in both the Fens (top) and Salisbury Plain (bottom). Triangles = three-compartment sparing.
The sustainability caveat
Our study was not designed to identify the ‘maximum sustainable yield’ capable of being delivered by a particular farmed landscape, so a major caveat is whether the high-yielding farmland envisaged under our sparing scenarios is future-proof. To be absolutely clear, any versions of land sparing which erode future production by exhausting finite resources such as soil are, by definition, unsustainable into the future, and are therefore unacceptable.
How we deliver long-term sustainable farming systems is an ongoing challenge, but it seems likely that fine-scale changes in land cover (e.g. hedges and buffer strips) and land management (e.g. cover crops, diverse legume-rich rotations) could go a long way towards ensuring that the high-yielding arable-dominated systems envisaged under our sparing scenarios contribute to healthy diets without exhausting soil health and whilst reducing their reliance on external inputs.
What does it mean for policy?
We don’t intend for our scenarios to be used as blueprints for future land-use in these (or other) regions, but our research does point towards the need for a land use strategy which incentivises land managers in different places to fulfil different roles. Here, Alice Groom explores what our research might mean for land management policy.
For the paper in British Ecological Society: Evaluating spatially explicit sharing-sparing scenarios for multiple environmental outcomes
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