Land cover and land use

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In addition to emissions, land cover and land use are key linkages between the Human system and the Earth system. Land cover and use are changed by humans for a variety of purposes, such as to produce food, fibres, timber and energy, to raise animals, for shelter and housing, transport infrastructure, tourism, and recreation. These human activities have affected most areas in the world, transforming natural areas to human-dominated landscapes, changing ecosystem structure and species distribution, and water, nutrient and carbon cycles. Natural landscape characteristics and land cover also affect humans, determining suitable areas for settlement and agriculture, and delivering a wide range of ecosystem services. As such, land cover and land use can be understood as the complex description of the state and processes in a land system in a certain location. It results from the interplay of natural and human processes, such as crop cultivation, fertilizer input, livestock density, type of natural vegetation, forest management history, and built-up areas.

In IMAGE, elements of land cover and land use are calculated in several components, namely in land use allocation, forest management, livestock systems, carbon cycle and natural vegetation. The output from these components forms a description of gridded global land cover and land use that is used in these and other components of IMAGE. In addition, this description of gridded land cover and land use per time step can be provided as IMAGE scenario information to partners and other models for their specific assessments.

Model description

Land cover and land use described in an IMAGE scenario is a compilation of output from various IMAGE components. This compilation provides insight into key processes in land-use change described in the model and an overview of all gridded land cover and land use information available in IMAGE (Input/Output Table below).

Land cover and land use is also the basis for the land availability assessment, which provides information on regional land supply to the agro-economic model, based on potential crop yields, protected areas, and external datasets such as slope, soil properties, and wetlands (Mandryk et al., 2015; Van der Esch et al., 2017).

Impacts on Terrestrial Biodiversity

Changes in land cover and land use, as well as other drivers, impact biodiversity. The impacts on terrestrial biodiversity are generally calculated by the GLOBIO Model (Schipper et al., 2020). However, IMAGE-Land can directly provide two biodiversity indicators, the Mean Species Abundance (MSA) and the Biodiversity Intactness Index (BII), see section Terrestrial biodiversity for details.

Input/Output Table

Input Land cover and land use component

IMAGE model drivers and variablesDescriptionSource
Built-up area - grid Urban built-up area per grid cell, excluded from all biophysical modelling in IMAGE, increasing over time as a function of urban population and a country- and scenario-specific urban density curve. Drivers
Protected area - grid Map of protected nature areas, limiting use of this area. Drivers
Irrigation water withdrawal - grid Water withdrawn for irrigation, not necessarily equal to the withdrawal demand, because of limited water availability in rivers, lakes, reservoirs and other sources. Water
Carbon pools in vegetation - grid Carbon pools in leaves, stems, branches and roots). Carbon cycle and natural vegetation
Change in soil properties - grid Change in soil properties, such as clay/sand content, organic carbon content, soil depth (topsoil/subsoil). Land degradation
Crop fraction in agricultural area - grid Fraction of agricultural land by crop type, per grid cell. Land-use allocation
Forest management type - grid Forest management type: clear cut, selective logging, forest plantation or additional deforestation. Forest management
Potential natural vegetation - grid Potential natural vegetation type/biome, based on distribution of plant functional types. Carbon cycle and natural vegetation
Bioenergy area Area of bioenergy crop production, in model setting where sustainability criteria require that the area for bioenergy crops is not included in the agricultural production area (to avoid competition between bioenergy and food). Land-use allocation
MSA (mean species abundance) - grid Mean Species Abundance (MSA) relative to the natural state of original species. Terrestrial biodiversity
Regrowth forest area - grid Areas of re-growing forests after agricultural abandonment or timber harvest. Forest management
NPP (net primary production) - grid CO2 sequestered by plants and incorporated in new tissue in plant carbon pools. Carbon cycle and natural vegetation
Extensive grassland area - grid Extensive pasture with low productivity used for grazing. Land-use allocation
Biodiversity Intactness Index (BII) – grid The average abundance across a set of species in each area relative to their reference population, which would be populations before any humans impacts but are usually populations in the least impacted settings available Terrestrial biodiversity
Harvested wood Wood harvested and removed. Forest management
Carbon pools in soil and timber - grid Carbon biomass in three soil pools (litter, humus and charcoal) and two timber pools (slow decaying, and fast decaying). Carbon cycle and natural vegetation
Management intensity crops Management intensity crops, expressing actual yield level compared to potential yield. While potential yield is calculated for each grid cell, this parameter is expressed at the regional level. This parameter is based on data and exogenous assumptions - current practice and technological change in agriculture - and is endogenously adapted in the agro-economic model. Agricultural economy
Agricultural area - grid Total area for crop production (annual and perennial) and intensive grassland. Land-use allocation
Degraded forest area Permanently deforested areas for reasons other than expansion of agricultural land (calibrated to FAO deforestation statistics). Forest management
Water withdrawal other sectors - grid Total annual and monthly water withdrawal for households, industry and electricity. Not necessarily equal to the withdrawal demand, due to limited water availability. Water
Management intensity livestock Management intensity of livestock, expressed at the regional level. This parameter is based on data and exogenous assumptions, i.e. current practice and technological change in livestock sectors, and is endogenously adapted within the Agricultural economy component. Agricultural economy
Intensive grassland area Intensively used grassland areas for grazing or mowing, at locations also suitable for crop production. Land-use allocation

Output Land cover and land use component

IMAGE model variablesDescriptionUse
Land supply for bioenergy - grid Land available for sustainable bioenergy production (abandoned agricultural land and non-forested land).
Land supply Available land for agriculture, per grid or region, depending on suitability for crops, and excluding unsuitable areas such as steep slopes, wetlands and protected areas.
Land cover, land use - grid Multi-dimensional map describing all aspects of land cover and land use per grid cell, such as type of natural vegetation, crop and grass fraction, crop management, fertiliser and manure input, livestock density.