Evaluating vegetation indices for assessing productivity along a tropical rain forest chronosequence in Western Amazonia

Abstract

Tropical deforestation is leading not only to losses of biodiversity but also to regional losses of vegetation productivity. However, in many areas the deforestation process is usually accompanied by a fast forest regeneration that produces a mosaic of forest patches in different successional stages. These successional stages have different productivities owing primarily to differences in species composition and soil nutrients. In order to assess the long-term consequences of deforestation and forest regeneration on atmospheric carbon dynamics, it is imperative to analyze the spatio-temporal patterns of forest productivity along different successional stages. This study evaluates the suitability of five different vegetation indices for assessing productivity along a tropical rain forest chronosequence located in Western Amazonia. Among the indices tested, the Red Edge Chlorophyll Index (CI_{Red Edge}) and the Wide Dynamic Range Vegetation Index (WDRVI) proved to be the most suitable for this purpose. However, due to the current low availability of multi-spectral imagery acquired by spaceborne sensors with a band in the red edge region of the electromagnetic spectrum, the WDRVI serves as the most practical index. The dynamics of the regional productivity in the study area during the 2000s were assessed using the WDRVI and proved to be consistent with observed land cover dynamics.

Keywords:

• Chlorophyll indices
• EVI
• Hyperion
• Landsat
• NDVI
• WDRVI