Authors: Molly Polk*, University of Texas at Austin, Niti B. Mishra, University of Wisconsin – La Crosse, Kenneth R. Young, University of Texas at Austin
Topics: Land Use and Land Cover Change, Remote Sensing, Latin America
Keywords: NDVI time-series, Theil-Sen trend, Greening, Browning, Ecoregions, Land use/Land cover change, Latin America, MODIS
Session Type: Paper
Start / End Time: 9:55 AM / 11:35 AM
Room: Hoover, Marriott, Mezzanine Level
Presentation File: No File Uploaded
Peru is a hotspot for biological diversity, and encompasses an array of natural environments, from hyperarid deserts to the forests of the Amazon. Yet these heterogeneous environments are showing near universal greening. Almost all of the strongly significant trends in changing vegetation were positive over a 17-year time series of MODIS imagery. Upon closer examination of the data, we posit that these trends are due to globally influenced trends in climate processes, combined with more localized processes of land cover disturbance, in many cases mediated by a direct or indirect human role. Our land-systems approach utilized a robust trend analysis of a MODIS-derived vegetation index to detect significant changes in inter-annual vegetation productivity (greening versus browning). On the coastal plain of Peru, greening was mostly due to the expansion of agriculture. In the Andes Mountains, greening was associated with expanding forest plantations and shrub expansion; that is, due both to the planting of non-native trees and the colonization of grasslands by native shrubs. The predominant patterns in Peru’s Amazon were strips of greening along meandering river channels, typically on inside river curves where plant colonization of new substrates occurred. Anthropogenic influences were also visible in the Amazon, with mostly greening, although other areas were losing photosynthetic material due to deforestation, mining, and other rural development activities. Elsewhere, areas of browning could be ascribed to urban expansion and other land-use transitions. The greening trends were not concentrated in areas protected for biodiversity, implying they were not the result of conservation efforts.