They then combined the time series of maps with forest inventory data on tree species diversity and carbon storage. They also characterized what drives both the spatial patterns of forest clearing for urbanization and the spatial patterns of forest recovery after large scale deforestation.
Based on their results and a synthesis of other work, the study concluded that accessibility, arability and spatial contagion emerge strongly as the overriding spatial controls on tropical forest age, determining 1) the pattern of agricultural abandonment that permits forest regrowth, and 2) where humans leave old-growth forest remnants. In addition, similarities between the factors patterning forest age and land development explain why most forest cleared for land development is younger. Forests are increasingly younger in more accessible and fertile areas where agriculture has lasted longer and land development is most common. All else equal, more species-rich older forest on less arable lands are somewhat less likely to undergo development, but they are still vulnerable to clearing for land development if close to urban centers and unprotected. Accounting for forest age leads to a 19 percent lower estimate of forest biomass cleared for land development than if forest age is not accounted for.
Contributor: Eileen H. Helmer, USDA Forest Service
Helmer, E.H., T.J. Brandeis, A.E. Lugo, and T. Kennaway (2008). Factors influencing spatial pattern in tropical forest clearance and stand age: Implications for carbon storage and species diversity. Journal of Geophysical Research, vol. 113, G02S04.
Kennaway, T. and E.H. Helmer (2007). The Forest Types and Ages Cleared from Land Development in Puerto Rico. GIScience & Remote Sensing, vol. 44, no. 4, pp: 356–382.
Safeguarding freshwater resources is crucial, and while scientists use a variety of ground-based techniques to gauge water quality, the Landsat program has provided water quality data from orbit for decades.