The loss of carbon stocks through agricultural land-use change is a key driver of greenhouse gas emissions [], and the methods used to manage agricultural land will have major impacts on the global climate in the 21century []. It remains unresolved whether carbon losses would be minimized by increasing farm yields and limiting the conversion of natural habitats (“land sparing”), or maximizing on-farm carbon stocks, even at the cost of reduced yields and therefore greater habitat clearance (“land sharing”). In this paper, we use field surveys of over 11,000 trees, in-depth interviews with farmers, and existing agricultural data, to evaluate the potential impacts of these contrasting approaches, and plausible intermediate strategies, on above-ground carbon stocks across a diverse range of agricultural and natural systems. Our analyses include agroforestry and oil palm plantations in the humid tropics of Ghana; cattle ranching in dry tropical forest in Mexico; and arable cropping in temperate wetlands and forests in Poland. Strikingly, despite the range of systems investigated, land sparing consistently had a higher potential to sustain regional above-ground carbon stocks than any other strategy. This was the case in all three regions and at all plausible levels of food production, including falls in demand. However, if agricultural production increases to meet likely future demand levels, we project large decreases in above-ground carbon stocks, regardless of land-use strategy. Our results strongly suggest that maintaining above-ground carbon stocks will depend on both limiting future food demand and minimizing agricultural expansion through linking high-yield farming with conserving or restoring natural habitats.

Across all regions, projected above-ground carbon stocks decreased under all land-use strategies as production levels increased, but land sparing consistently resulted in greater regional stocks than any other strategy ( Figure 3 Figure S3 ). Land sharing consistently resulted in lower stocks than any of the 148 intermediate strategies we examined, although the relative difference varied between regions, being greater in Poland, which had very low above-ground stocks on any agricultural land, than in Ghana or Mexico, where low-yield sites maintained slightly higher stocks ( Figure 1 ). As yields in intermediate strategies increased, so did projected regional carbon stocks because strategies became more similar to land sparing, and greater areas of baseline habitats were projected to survive ( Figure S4 ).

Projected mean above-ground carbon stocks averaged across entire study regions under different land use strategies at different production levels. Dark colors show projected stocks under projected 2050 production levels; intermediate colors show stocks under 2014 production levels; light colors show stocks with production at 50% of 2014 levels. We tested 148 possible intermediate strategies but show the results for when yields are halfway between those under land sharing and land sparing. Error bars show the bootstrapped 95% confidence intervals around estimates—see Quantification and Statistical Analysis in STAR Methods for details and Figures S3 and S4 for explanation as to why, despite the overlap of confidence intervals, we conclude that land sparing outperforms all other strategies.

Projected Mean Above-Ground Carbon Stocks Averaged across Entire Study Regions under Different Land Use Strategies at Different Production Levels

Figure 3 Projected Mean Above-Ground Carbon Stocks Averaged across Entire Study Regions under Different Land Use Strategies at Different Production Levels

To assess the potential impacts of different land-use strategies on regional carbon stocks, we calculated a range of plausible future agricultural demand levels, from close to zero to probable 2050 demand levels. We estimated the agricultural land required to meet each demand level, at all plausible yields, from the lowest yields that could meet demand to 125% of current maximum observed yield in each region, assigning remaining land to natural habitats ( Figure 2 ). Finally, we used the relationships between yield and above-ground carbon stock density ( Figure 1 ) to estimate carbon stocks in both the agricultural and non-agricultural land, summing the two to obtain a regional estimate, and dividing by the area of the region to obtain a mean above-ground carbon stock across the region (see STAR Methods for details).

Schematic of three different land-use strategies: land sharing uses all available land at the lowest possible yields; land sparing maximizes yields and conserves natural habitats; intermediate strategies use yields between these two extremes. All landscapes produce the same amount of food, with numbers representing the relative yields of different agricultural lands. We show a representative intermediate strategy but tested hundreds of strategies between land sharing and land sparing.

Schematic of Three Different Land-Use Strategies: Land Sharing Uses All Available Land at the Lowest Possible Yields

Figure 2 Schematic of Three Different Land-Use Strategies: Land Sharing Uses All Available Land at the Lowest Possible Yields

For each region, we fitted flexible non-linear functions to the data and found that relationships were similar across regions, with consistent, rapid declines in above-ground carbon stocks between natural habitats and agricultural sites ( Figure 1 ). There were two minor exceptions: in Ghana, calorific yields were highest in oil palm plantations, which also contained higher carbon stocks than most intermediate- and low-yielding sites consisting of small-holder mixed cropping systems. Stocks in oil palm, however, remained well below those in zero-yielding forests. In Poland, above-ground stocks in sites on organic soils were highest at very low yields but remained well below stocks in forest sites.

Relationships between above-ground carbon stock density and agricultural yield in three farming systems. Shaded areas show the bootstrapped 95% confidence intervals around estimates. See STAR Methods for details on yield and carbon stock estimation and modeling approach. See Figure S1 for separate curves fitted to different soil types in Poland and Figure S2 for the uncapped curve for Ghana.

To model the relationship between above-ground carbon stocks and agricultural yields, we measured tree biomass at sample points in 25 or 26 1-kmsites in each region, across a range of agricultural yields, from zero-yielding natural habitats to high-yield agriculture. In Ghana, sites ranged from moist evergreen and moist semi-deciduous tropical forest through mosaics of agroforestry, remnant vegetation, and mixed agriculture, to oil palm plantations. In Mexico, we investigated tropical dry and semi-deciduous forests and cattle ranching systems, from low intensity grazing on pastures and natural vegetation through to intensively managed improved pastures and supporting maize production. Finally, in Poland, we sampled fen mires and flood plains on organic soils and temperate mixed deciduous forests on mineral soils as natural habitats, and a gradient from mixed agriculture to intensive arable farms. See STAR Methods for details on yield and carbon stock estimation and modeling approach.

Discussion

10 Green R.E.

Cornell S.J.

Scharlemann J.P.

Balmford A. Farming and the fate of wild nature. Despite the wide range of ecosystems and farming systems we investigated, patterns in above-ground carbon stocks were remarkably consistent: in each system, stocks were far lower on agricultural sites of any yield than in natural habitats, and differences between agricultural sites of different yields were relatively small. The rare exceptions—in organic soil sites in Poland, and high-yield sites in Ghana—did not alter this overall pattern. We also projected consistent declines in regional stocks as agricultural production increased. These results strongly suggest that minimizing agricultural expansion will conserve regional above-ground carbon stocks to a greater extent than attempting to conserve stocks on agricultural land. For any given level of agricultural production, this will require maximizing agricultural yields and linking yield increases to natural habitat conservation: a land sparing approach [].

11 Tscharntke T.

Clough Y.

Wanger T.C.

Jackson L.

Motzke I.

Perfecto I.

Vandermeer J.

Whitbread A. Global food security, biodiversity conservation and the future of agricultural intensification. 12 Kremen C. Reframing the land-sparing/land-sharing debate for biodiversity conservation. Ann. 11 Tscharntke T.

Clough Y.

Wanger T.C.

Jackson L.

Motzke I.

Perfecto I.

Vandermeer J.

Whitbread A. Global food security, biodiversity conservation and the future of agricultural intensification. Importantly, land-sparing scenarios resulted in lower stock losses, relative to a landscape consisting entirely of natural habitat, than all other strategies and at all realistic production targets, including reductions in production. The land sparing-land sharing continuum has been characterized as a dichotomy [] or based on the assumption that food production must increase []; our results show that, for our diverse study systems and for above-ground carbon stocks, neither characterization is justified. Rather, land sparing has the potential to outperform all other agricultural strategies we modeled, and to do so at all plausible production targets. Indeed, land-sparing scenarios had the greatest advantage over land-sharing strategies at lower production targets.

13 Gilroy J.J.

Woodcock P.

Edwards F.A.

Wheeler C.

Medina Uribe C.A.

Haugaasen T.

Edwards D.P. Optimizing carbon storage and biodiversity protection in tropical agricultural landscapes. 14 Wade A.

Asase A.

Hadley P.

Mason J.

Ofori-Frimpong K.

Preece D.

Spring N.

Norris K. Management strategies for maximizing carbon storage and tree species diversity in cocoa-growing landscapes. 15 Williams D.R.

Alvarado F.

Green R.E.

Manica A.

Phalan B.

Balmford A. Land-use strategies to balance livestock production, biodiversity conservation and carbon storage in Yucatán, Mexico. 15 Williams D.R.

Alvarado F.

Green R.E.

Manica A.

Phalan B.

Balmford A. Land-use strategies to balance livestock production, biodiversity conservation and carbon storage in Yucatán, Mexico. 16 Jobbágy E.G.

Jackson R.B. The Vertical Distribution of Soil Organic Carbon and Its Relation to Climate and Vegetation. 17 Fisher M.J.

Thomas R.J. Implications of land use change to introduced pastures on carbon stocks in the central lowlands of tropical South America. Our analyses strongly imply that minimizing agricultural expansion through limiting growth in demand, and combining high-yield agriculture with natural habitat protection has the greatest potential for conserving carbon stocks. This supports previous work investigating the potential impacts of land-use strategies on carbon stocks [], which found that stocks declined as production targets increased and that land sparing has the potential to minimize the trade-off between regional food production and carbon stocks. Our analyses expand this work by exploring a wide range of agricultural yields and comparing all feasible land-use strategies, as well as using a consistent analytical framework across a diversity of regions. Our results using this framework also support a previous analysis of the Mexican study system based on a more complex scenario-building approach []—suggesting our main conclusion may be robust to the exact analytical method used. Given the breadth of our study systems in terms of climate, natural habitats, and agricultural systems, it also seems likely that these results hold for other naturally forested systems, or habitat types with considerable above-ground carbon stocks, though may not necessarily apply in systems such as grasslands, where most biomass is below ground [].

18 Cairns M.A.

Brown S.

Helmer E.H.

Baumgardner G.A. Root biomass allocation in the world’s upland forests. 19 Guo L.B.

Gifford R.M. Soil carbon stocks and land use change: a meta analysis. 20 Amundson R.

Berhe A.A.

Hopmans J.W.

Olson C.

Sztein A.E.

Sparks D.L. Soil science. Soil and human security in the 21st century. 21 Scheidel A. Carbon stock indicators: reductionist assessments and contentious policies on land use. 6 Tilman D.

Balzer C.

Hill J.

Befort B.L. Global food demand and the sustainable intensification of agriculture. 5 Burney J.A.

Davis S.J.

Lobell D.B. Greenhouse gas mitigation by agricultural intensification. 22 Lamb A.

Green R.

Bateman I.

Broadmeadow M.

Bruce T.

Burney J.

Carey P.

Chadwick D.

Crane E.

Field R.

et al. The potential for land sparing to offset greenhouse gas emissions from agriculture. We were not able to include data on below-ground carbon stocks or carbon fluxes but have several reasons to believe that their inclusion would not change our overall findings. Carbon stocks in below-ground biomass are typically closely correlated with above-ground biomass [] and so likely show similar responses to agricultural yields. Soil organic carbon also shows large declines with conversion from natural habitats to most agricultural lands [], and while yield increases may result in additional losses, it seems likely that these initial declines are greater than subsequent changes—again meaning that land sparing would have the greatest potential for carbon retention. The climate-change impacts of land-use strategies will depend on both carbon stocks and net greenhouse gas emissions [], which can increase with yields []. If this increase were sufficiently large, then it could counter the benefits of greater landscape-wide retention of carbon stocks that land sparing permits. However, differences in fluxes from high-yield, compared to low-yield, systems are small relative to changes in carbon stocks from conversion to agriculture, meaning that land sparing is still likely to minimize carbon emissions [].

23 Koh L.P.

Levang P.

Ghazoul J. Designer landscapes for sustainable biofuels. 24 Berenguer E.

Ferreira J.

Gardner T.A.

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De Camargo P.B.

Cerri C.E.

Durigan M.

Cosme De Oliveira Junior R.

Vieira I.C.

Barlow J. A large-scale field assessment of carbon stocks in human-modified tropical forests. 25 Brinck K.

Fischer R.

Groeneveld J.

Lehmann S.

Dantas De Paula M.

Pütz S.

Sexton J.O.

Song D.

Huth A. High resolution analysis of tropical forest fragmentation and its impact on the global carbon cycle. Using low-yield, relatively high-carbon farming has been suggested as a strategy to reduce edge effects and increase connectivity between spared patches []. However, such a strategy will necessarily reduce the area of land spared and will only outperform land sparing if edge effects greatly reduce carbon stocks in natural habitats but are largely eliminated when natural habitats abut low-yield farming. The small differences in carbon stocks between agricultural sites of different yields, and the large declines compared to natural habitats, do not suggest that these conditions are present in our study systems. Similarly, while previous analyses [] suggest that edge effects could reduce regional carbon stocks under land-sparing and intermediate strategies, the very low stocks under land sharing mean any such changes are unlikely to alter our conclusions.

1 Gibbs H.K.

Brown S.

Niles J.O.

Foley J.A. Monitoring and estimating tropical forest carbon stocks: making REDD a reality. 6 Tilman D.

Balzer C.

Hill J.

Befort B.L. Global food demand and the sustainable intensification of agriculture. 26 Fisher B.

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Balmford A. Implementation and opportunity costs of reducing deforestation and forest degradation in Tanzania. 27 Albrecht A.

Kandji S.T. Carbon sequestration in tropical agroforestry systems. 28 Broom D.M.

Galindo F.A.

Murgueitio E. Sustainable, efficient livestock production with high biodiversity and good welfare for animals. Our results provide insights for the UN’s Reducing Emissions from Deforestation and Forest Degradation program (REDD) [], highlighting the value of focusing on coupled efforts to boost farm yields and slow habitat conversion []. However, our findings suggest that efforts to increase on-farm above-ground carbon stocks—for example, through the planting of shade trees [] —are unlikely to maintain regional stocks if interventions involve a yield penalty, as they do in the systems we studied. Interventions that increase carbon stocks without reducing agricultural yields could be effective. For example, intensive silvopastoral systems involving banks of protein-rich woody legumes may increase both yields and on-farm carbon []. However, our results strongly suggest such approaches should be used as part of a land-sparing strategy and explicitly linked to habitat conservation rather than being used to compensate for the loss of natural habitats.

29 Kaimowitz D.

Angelsen A. Will Livestock Intensification Help Save Latin America’s Tropical Forests?. 30 Ewers R.M.

Scharlemann J.

Balmford A.

Green R. Do increases in agricultural yield spare land for nature?. 31 Angelsen A. Policies for reduced deforestation and their impact on agricultural production. 32 Ewers R.M.

Rodrigues A.S.L. Estimates of reserve effectiveness are confounded by leakage. 33 Oliveira P.J.C.

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Galván-Gildemeister R.

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Smith R.C. Land-use allocation protects the Peruvian Amazon. 34 Desquilbet M.

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Couvet D. Land Sharing vs Land Sparing to Conserve Biodiversity: How Agricultural Markets Make the Difference. 26 Fisher B.

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Balmford A. Implementation and opportunity costs of reducing deforestation and forest degradation in Tanzania. 35 Phalan B.

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Feniuk C.

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Strassburg B.B.N.

Williams D.R.

zu Ermgassen E.K.

Balmford A. CONSERVATION ECOLOGY. How can higher-yield farming help to spare nature?. Despite its advantages, land sparing is unlikely to occur passively; rebound effects mean that increasing yields may not reduce local land clearance if it increases the profitability of farming, particularly for goods with highly elastic demand such as palm oil or meat [], while protecting habitats may not benefit regional carbon stocks if there is leakage of habitat clearance to other areas []. The far lower stocks on agricultural land, compared to natural habitats, mean that any degree of land sparing is likely to reduce the loss of regional carbon stocks [], but rebound and leakage will reduce these benefits. Instead, “active land sparing” will be needed: the coupling of yield increases with habitat protection through land-use zoning; economic instruments such as taxes or subsidies; strategic investment to alter the relative profitability of agriculture near and far from agricultural frontiers; or environmental standards and certifications [].

13 Gilroy J.J.

Woodcock P.

Edwards F.A.

Wheeler C.

Medina Uribe C.A.

Haugaasen T.

Edwards D.P. Optimizing carbon storage and biodiversity protection in tropical agricultural landscapes. 15 Williams D.R.

Alvarado F.

Green R.E.

Manica A.

Phalan B.

Balmford A. Land-use strategies to balance livestock production, biodiversity conservation and carbon storage in Yucatán, Mexico. 36 Phalan B.

Onial M.

Balmford A.

Green R.E. Reconciling food production and biodiversity conservation: land sharing and land sparing compared. 37 Dotta G.

Phalan B.

Silva T.W.

Green R.

Balmford A. Assessing strategies to reconcile agriculture and bird conservation in the temperate grasslands of South America. 38 Hulme M.F.

Vickery J.A.

Green R.E.

Phalan B.

Chamberlain D.E.

Pomeroy D.E.

Nalwanga D.

Mushabe D.

Katebaka R.

Bolwig S.

Atkinson P.W. Conserving the birds of Uganda’s banana-coffee arc: land sparing and land sharing compared. 39 Kamp J.

Urazaliev R.

Balmford A.

Donald P.F.

Green R.E.

Lamb A.J.

Phalan B. Agricultural development and the conservation of avian biodiversity on the Eurasian steppes: a comparison of land-sparing and land-sharing approaches. 40 Bennett E.M. Changing the agriculture and environment conversation. 41 Foley J.A.

Defries R.

Asner G.P.

Barford C.

Bonan G.

Carpenter S.R.

Chapin F.S.

Coe M.T.

Daily G.C.

Gibbs H.K.

et al. Global consequences of land use. 42 Carpenter S.R.

Caraco N.F.

Correll D.L.

Howarth R.W.

Sharpley A.N.

Smith V.H. Nonpoint pollution of surface waters with phosphorus and nitrogen. 43 Hornigold K.

Lake I.

Dolman P. Recreational Use of the Countryside: No Evidence that High Nature Value Enhances a Key Ecosystem Service. 21 Scheidel A. Carbon stock indicators: reductionist assessments and contentious policies on land use. Our results complement multiple analyses that have found similar and consistent results for trade-offs between biodiversity and food production across the world []; for each region and taxon, land sparing was projected to conserve larger populations of more species than any other strategy. Relationships between agricultural land-use strategies and the provision of other ecosystem services is less clear []. If on-farm ecosystem services to agriculture—such as pollination or pest control—increase yields, after allowing for any land taken out of production in order to maintain them, then conserving them can be part of a land-sparing strategy, so there need be no conflict between their retention and conserving carbon stocks or biodiversity. If, however, there is a trade-off between food production and service provision—as may be likely for water quality maintenance [] or cultural services []—then the least damaging land-use strategy will be determined by the exact nature of this relationship, and there remains the possibility of trade-offs between services. Finally, how land-use strategies interact with and affect the livelihoods and welfare of local people—both farmers and those dependent on natural habitats—is likely to depend on local and national context. Each strategy is likely to result in winners and losers, and ensuring that land-use plans are fair and equitable is a major challenge for researchers and policy makers [].