Lecture 20: Land-use/Land Cover Change Notes

Land-use and Land Cover – terminology differences

  • Land-use effects land cover

Land-use: how humans “utilize or modify” land

  • eg. Socio-economic activity – timber production, recreation, agriculture, urban

Land Cover: type of vegetation or physical material at the surface

  • eg. Deciduous forest, grassland, row crops, wetland, water, impervious surface of built environment

Scale-dependent
Differences in scale can result in different interpretations of the landscape mosaic. The resolution allows us to distinguish or differentiate the objects or spatial elements within it. The grain refers to the coarseness in texture or granularity of spatial elements composing an area. A fine-grained landscape has small patches, and a coarse-grained landscape is composed of large patches.

If we zoom out, we can see a greater extent or more of the image.

  • Class example of Minnesota Lakes or Maine coastline.

Key point: interpretation of a landscape is scale-dependent. Different resolutions can yield different results of quantitative metrics of landscape structures such as edge to interior ratio and quantification of habitat type. There is no right answer, which therein lays the challenge.

Landscape Ecology
Branch of ecology that focuses on ecological processes related to habitat patch shape, sizes, adjacencies, and scales of landscape patterns
- Basic spatial elements of any patterns on land are patches, corridors, and matrixes
- Boundaries separate spatial elements and vary widely in structure and size.
- Edge is the outer portion or edge of a patch or other spatial element

A patch is a relatively homogenous area that differs from its surroundings and can have an irregular shape. Patch shape and size are important characteristics in addressing habitat and ecosystem management.

Corridors are generally narrow strips of habitat that facilitate the movement of organisms between adjacent habitat fragments.

Matrix is the background ecosystem or land-use type in a mosaic, characterized by extensive cover, connectivity or major control over dynamics.

Habitat Fragmentation
Land cover change can occur through…
Natural processes: disturbance and succession.
Anthropogenic processes: deforestation and conversion to agriculture, agriculture abandonment, urbanization (surbubanization), etc. This is the most common and threatening to land cover change.

Examples
Deforestation → reforestation
“Old-field” succession occurs when abandoned farmland allows for plants and animal species to colonize. A commonly cited example of ecological succession is farmland in northeastern United States where land converted into agriculture in the 19th century was eventually abandoned, allowing reforestation of the area.

Forest → Agriculture
The conversion of tropical forest to palm oil plantations throughout Indonesia and Malaysia releases a large amount of C into the atmosphere and poses a threat to habitats and biodiversity.

Effects of Forest Fragmentation

  • Changes in land-use affect fluxes of C into the atmosphere.
  • More forest edge
  • Less forest interior
  • Reduced species abundance and biodiversity
  • Loss of forest corridors for animal movement
  • Average patch size decreases
  • Patch isolation increases
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