Concepts of Land Use Change

Significance of Land Use Change

  • Primary global cause of biodiversity population declines and extinctions.

  • Interacts with climate change stressors and impacts ecosystem service provision.

Land Cover versus Land Use

  • Land Cover: Physical surface material (e.g., forest); quantifiable via satellites and maps.

  • Land Use: Human activity or purpose on the land (e.g., urban housing density, agricultural intensity); harder to detect remotely than cover.

Landscape Fragmentation (McIntyre & Hobbs, 1999)

  • Intact: > 90\% habitat.

  • Variegated: 60–90%60\text{--}90\% habitat.

  • Fragmented: 10–60%10\text{--}60\% habitat.

  • Relictual: < 10\% habitat.

Global Changes 1982-2016 (Song et al., 2018)

  • Tree cover: Increased by +7.1%+7.1\% (decreases in tropics; increases in temperate, boreal, and subtropical areas).

  • Short vegetation: Decreased by −1.4%-1.4\% (increases in tropics; mirror image of tree cover).

  • Bare ground: Decreased by −3.1%-3.1\% (increases in subtropical desert and steppe).

  • Drivers: 60%60\% attributed to direct human land use change; 40%40\% attributed to indirect drivers like climate change.

Monitoring and Biomass Contributions

  • Brandt et al. (2020): Identified 1.8 billion1.8\,\text{billion} trees with canopy > 3\,\text{m}^2 across 1.3 million km21.3\,\text{million}\,\text{km}^2 of the West African Sahara and Sahel.

  • Liu et al. (2023): Trees outside forests (e.g., 10%10\% in the UK) are critical for biomass and carbon sequestration.

Long-term Drivers and Projections

  • Hurtt et al. (2011): Gridded annual transitions between primary forest, agriculture, and urban land from 15001500 to 21002100.

  • Consumption Drivers: Increasing human population and per capita consumption (meat, dairy, timber).

  • Economic Factor: Requisite land area increases by 13\frac{1}{3} when income doubles.

Biodiversity Impacts (Newbold et al., 2015)

  • Study utilizes over 1 million1\,\text{million} records across ≈27,000\approx 27,000 species and 1313 biomes.

  • Estimated global species richness decline of 13.6%13.6\% since 15001500.

  • Richness declines reach up to 31%31\% in human-dominated areas; richness increased in < 2\% of global cells.

  • Influencing pressures: Land use intensity, human population density, proximity to roads, and accessibility to settlements.