Land-use Challenges
As the world’s population becomes more affluent (and numerous) our collective levels of consumption rise, putting ever greater pressures on land and making planning and managing its use increasingly complex. Professor Tim Benton walks us through the land-based interconnections between resources, and the challenges we face in ensuring the multiple uses of land are compatible with a sustainable future.
Land has many functions
Land provides many vital functions for ecosystems, biodiversity, and humanity. The interconnections between these result in inevitable trade-offs when choices are made about how land is used.
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Aesthetic
Landscapes have non-material benefits such as their perceived beauty and cultural importance
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Habitat
Land provides places to live for wildlife as well as humans; the more hospitable the habitat the more people or animals and plants can live there
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Industry
Industry places additional demand on resources both as raw materials for manufacture (e.g. timber) and to support processing (e.g. water cooling)
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Recreation
The characteristics of landscapes shape decisions about leisure activities, bringing well-being and economic benefits
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Fresh water
Land cover affects runoff, aquifer recharge and water purification. Freshwater supports multiple ecosystems and production systems
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Food
Plants, animals and microbes all provide food sources for one-another; changing dietary patterns among humans demands increasing resources
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Carbon storage
Ecosystems regulate the climate through emitting and sequestering greenhouse gases; land use change affects the balance
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Fuel
Wood, biological waste and energy crops all offer sources of energy
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Pollination
Vital for sustaining many plants, including some crops, insect pollinators require healthy habitats to sustain their populations
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Nutrients
Soils play a crucial role in nutrient cycling, but are threatened by overexploitation, and can take decades to recover
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Erosion control
Land cover and nutrient cycling affects soil fertility and plays an important role in regulating soil erosion
Land is a finite resource
36% of all land is agricultural - every person has a football pitch-sized portion to provide their food, clothes and fuel. By 2050 this is likely to reduce by a quarter. Local and global environmental limits are threatened by increasing demand.
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Food
Global demand for foods is increasing, requiring more land and water inputs; this pressure is exacerbated by the way we waste food
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Energy
Energy crops can replace some fossil fuel sources – but as demand for these crops increase so does the competition for land
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Fibres
We depend on agriculture for natural fibres, skins and hides for clothing and industrial purposes
Places are unique
Landscapes serve competing needs and reaching agreement on sustainable multifunctional land-use can be challenging. The ‘best’ action to take varies with place and depends on the idiosyncrasies of soils, climate, topography, and neighbouring land uses.
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Microclimates
Similar topographies with different aspects may differ in their suitability for growing crops. Land cover changes can affect local temperature and precipitation
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Woodland
Woodlands in mixed landscapes can reduce surface water runoff, prevent erosion and support biodiversity - all potentially useful to neighbouring farmland
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Settlement
Urban development on degraded or contaminated land unsuitable for agriculture can reduce pressures on fertile land
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Arable
Fertile floodplain soils may be best suited to high yielding crops
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Hills
Grazing livestock in uplands can preserve carbon sinks and support soils ill-suited for intensive farming
Land-use outcomes depend on scale
Restoring biodiversity may only succeed beyond a critical scale able to support viable populations. High rates of fertilizer use may have limited ecological impact in just one field, but may greatly affect soil, water, and biodiversity if applied across a landscape.
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Biodiversity
Biodiversity can flourish in landscapes with multiple land uses, and sufficiently sized and connected habitats
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Nutrient cycling
Synthetic fertilizers boost yields but, unlike traditional manure, do not provide inputs that maintain soil health and biodiversity
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Carbon storage
Soil health and carbon storage can be preserved or enhanced with crop rotations, fallow periods, and the application of manure
Trade-offs in scaling up
Economies of scale can bring production efficiencies but also sustainability costs. Landscapes of monocultures can destroy biodiversity and ecosystem services, and “crowd out” other more place-appropriate land-uses.
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Monoculture
Homogenization across a landscape allows for efficient cultivation and increased harvest volumes but can destroy natural habitats and biodiversity
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Pollution
Over-application of chemical inputs and agricultural by-products can lead to localized pollution and contamination of the local environment
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Greenhouse gases
Throughout the agricultural cycle, fossil fuel inputs generate greenhouse gases. Tilled land may release rather than sequester greenhouse gases
Trade connects land across borders
Different geographies and policy choices can create comparative advantage, leading to export-specialisation in certain goods (e.g. in ‘breadbasket’ regions), import-dependence for others, and land-use interdependencies across borders.
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Forest
As this country requires little production capacity and has limited export markets, land is plentiful allowing it to preserve forested areas
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Domestic supply
High consumer demand is largely met by domestic specialization
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Imports
As a largely self-sufficient country, food imports are limited
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Exports
Specialization means there is excess production that can be exported to other countries
Changing land use affects trade relationships
If land use in one place changes, e.g. to make it more sustainable, local production may decline. But if demand is inelastic, intensification or specialisation may result elsewhere. Globally, these spillovers may create ecological costs that outweigh the initial local benefits.
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Increased production
Demand from the other country remains high, but as it produces less, it incentivizes more production through the market
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Deforestation
Expansion of crop area leads to deforestation to support the new production
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Increased imports
As demand is no longer met domestically, the country increases its reliance on imports
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Decreased production
To protect the environment through less intensive farming, or to free up land for other uses, domestic production is traded off for other benefits
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Afforestation
With demand being met through trade, more land is available for afforestation and other land uses
Climate change adds complexity
The climate is changing: weather is more unpredictable and extreme events are more frequent. Land needs to be used better to mitigate and adapt to the changes but must also “do no harm” under uncertain future circumstances.
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No till
Directly drilling seeds into the soil without ploughing has mitigation and adaptation benefits, but demands more pesticides since tilling helps manage weeds
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Conventional
Excessive inputs might be applied in the face of uncertain weather as an ’insurance’ to maintain yields
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Afforestation
Afforestation and reforestation are important means of capturing greenhouse gases to mitigate the extent of climate change
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Organic
Reliance on ecological processes with low or no application of artificial inputs can support soil health and biodiversity, bringing adaptation and mitigation benefits, but reduced yields
Future weather impacts
The climate conditions that actually materialise will affect how successful different approaches to resilience and sustainability prove to be, further complicating land-use planning and the trade-offs to be made.
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Resilience
Organic and no till agriculture may fare better than conventional agriculture under extreme conditions and may recover better in the long run
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Extreme heat
Extreme heat can spark large-scale forest fires releasing all the carbon sequestered back into the atmosphere undoing the mitigation benefits
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Crop failure
Conventional agricultural practices may not be well-suited to future climatic extremes, without new genetic varieties
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Heavy rainfall
Intensive production may make soils more vulnerable to erosion and can influence flood risks; farming on wet land can damage soils further
Conclusion
Goods and services provided by land are intimately connected in multiple and complex ways, with synergies and trade-offs between different uses. The “best” mix of socially and environmentally appropriate land uses needs to be determined by cross-sectoral strategies, due to land’s scarcity, multifunctionality, and idiosyncrasies.
