Reconciling agriculture and biodiversity conservation: the ‘land sparing, land sharing’ debate

by Catherine Gresty, United Kingdom, ELP 2015

 

One evening, towards the end of Susan Carpenter’s Collaborative Leadership training, I entered into a discussion with fellow ELP delegates from 8 different countries around the world. The focus of the discussion, one of the most important challenges facing environmental leaders today: how best to manage our agricultural land to meet food security objectives while limiting further detrimental impact on ecosystems.

The expansion and intensification of agriculture has had a pervasive effect on ecosystems throughout the world. Croplands and pastures now constitute one of the largest terrestrial biomes on the planet, occupying 40% of the total land surface at the loss of 70% of the world’s grasslands, 50% of savannas and 45% of temperate deciduous forest (Foley, 2011) (Ramankutty, 2008). Over the next 50 years, the global population is forecast to rise to 8-10 billion and food demand will increase 2-3 fold (FAO, 2003). Ecosystems and the biodiversity they harbor provide a range of services of direct importance to agriculture including nutrient cycling, climate regulation and pollination. As we enter the next episode of global agricultural expansion, it is crucial we develop strategies to conserve and protect these ecosystem functions services alongside meeting the growing demands of the global population.

I am an ecologist by training, currently completing a PhD at Oxford University on how best to manage farmland to conserve bee populations. My fellow ELP participants were economists and I decided to introduce to them the debate on ‘land sparing’ versus ‘land sharing’, which dominates the ecological literature on this topic. It provides an interesting framework for conceptualizing the potential solutions to this challenge and my fellow participants encouraged me to share it more widely with the ELP community.

In the ecological literature, two alternate strategies have been proposed for managing land to reconcile agricultural production and biodiversity conservation: ‘land sparing’ and ‘land sharing’ (Balmford, 2012). ‘Land sparing’ strategies focus on intensifying existing farmland, capitalizing on these yield increases to spare as much unmodified habitat as possible from conversion (Goklany I. M, 1998). In contrast, under ‘land sharing’ biodiversity conservation is integrated into agricultural management by making existing farmland more hospitable to wild species, for example by retaining habitat elements such as hedgerows and shade trees and minimizing the application of pesticides and fertilizers (Balmford, 2012) (Tscharntke T, 2012).

Image icongresty-1-1024x330_2.jpg Figure 1 Diagram displaying gradient of land management strategies from land sharing to land sparing (Balmford et al, 2012)

There are advantages and disadvantages to both approaches and the optimum strategy, will inevitably vary according to the landscape and agricultural production system in question. In areas where there is still an abundance of natural habitat, land sparing may be a prudent strategy and has been demonstrated to be more effective in conserving specialist species that struggle to survive in sub-optimum habitat (Phalan, 2011). However, for land sparing to be effective, it is imperative that appropriate policies are put in place to ensure any gains in production from intensification on pre-existing farmland are actually translated into increases in the area of natural habitat being protected.

On the other hand, in areas where very few isolated and degraded patches of natural habitat remain, land sharing may be the best strategy to restore ecosystem functioning and service delivery at the landscape level (Tscharntke, 2012). Land sharing has the additional advantage of potentially creating greater levels of ecological connectivity across agricultural landscapes, facilitating the dispersal and migration of species. This is really important for maintaining the resilience of wild populations and facilitating range shifts in response to climate change. The major disadvantage of land sharing is that it is generally associated with decreases in agricultural yield, necessitating further conversion of unmodified habitats (Balmford, 2012).

Image icongresty-2-300x200_2.jpg Figure 2: Land Sparing – landscape of high yield farmland with protected areas of natural habitat set aside for biodiversity conservation

Image icongresty-3_2.jpg Figure 3: Land Sharing example - coffee agroforestry, coffee grown in high diversity system that mimics natural forest structure

Introduction to this debate ignited a really interesting discussion, exploring how these land management strategies might best be deployed to better reconcile agricultural production with environmental objectives. Most of my research has been in conducted in the UK where farmers are being encouraged to adopt land sparing strategies at the farm level (see figure 1c). It was fascinating to hear the opinions of my fellow ELP participants on the relative potential of these strategies to be deployed within their respective countries and crucially, how popular they might be with farmers.