TIME SERIES OF MICROWAVE DERIVED PRODUCTS: LOOKING FOR DISTURBANCES IN ARGENTINE CHACO FOREST REGION
IGARSS 2015 – Remote Sensing: Understanding the Earth for Safer Word – July 26-31, Milan, Italy.
Abstract: Monitoring forest disturbances is critical for addressing its impact on carbon storage and fluxes, biodiversity, and other socioecological processes. Satellite remote sensing enables cost-effective and accurate monitoring at frequent time steps over large areas. In order to extract meaningful information about vegetation land surface variations, a useful framework is to analyze the seasonal patterns of vegetation, known as land surface phenology (LSP), using time series data obtained by remote sensing systems. In this way, we can relate the ecosystem dynamics with land surface phenology variations [1]. Nowadays there is interest in studying the LSP using microwave an optical indexes [2], since both are able to generate complementary information about vegetation condition. There is a critical need for methods that enable analysis of satellite image time series to detect forest disturbances in near-real time, especially in developing countries (e.g. Argentina).
The region addressed in this paper is the Argentine part of the Chaco Region (Fig. 1), that covers 675.000 km2 (approximately 24% of the country). This large, not homogeneous region, in addition to having one of the largest native forests areas, presents temperature and humidity gradients with an increasing arid gradient from east to west which defines five distinct regions: Humid Chaco, Transition Chaco, Semiarid Chaco, Arid Chaco and Hilly Chaco (see Figure 1). There are several native forest species, but the dominating ones are “Quebracho colorado santiagueño” (Schinopsis quebracho colorado) and “Quebracho Blanco” (Aspidosperma quebracho blanco).
Although there are areas of continuous forest, extensive measurements indicate moderate values of biomass typically in the range 70–110 t/ha (7–11 kg/m). Nowadays one of the most important threat to this forest is the fast expansion of agriculture (mainly soybean). Moreover, the expansion of livestock has also been documented as a major driver of deforestation in recent years, especially in north-west Argentina around the Chaco area, due the international demand of those products.