Comparative analysis of insect outbreak impact detection over forests in northwestern USA from MODIS and SENTINEL-2 sensors
Abstract
Global forest ecosystems act as a large sink of anthropogenic CO2 emissions. However, they are susceptible to multiple disturbances, that can impair their CO2 uptake potential. According to the Global Forest Resources Assessment 2010, insect outbreaks can affect larger extents than wildfires in some countries in the Northern Hemisphere. However, at global scale these disturbances remain understudied since there are currently no globally-consistent and homogeneous insect disturbance records.
Different satellite products are freely available and allow monitoring different kinds of forest disturbances consistently over the globe. The Moderate Resolution Imaging Spectroradiometer (MODIS) offers a long time series since 1999 and daily acquisition rate, but comes with a relatively low spatial resolution (250m). Landsat TM-Data are available for more than 40 years, with a resolution of 30m but just a few images per growing season, which make it difficult to detect defoliator impacts. SENTINEL-2, which launched in 2015, combines the advantage of a high spatial resolution (10-30m) and an overpass frequency of five days, but has the disadvantage of yet short-time series. In this study we compare the potential of MODIS and SENTINEL-2 data to track the evolution of forest activity in response to different types of insect outbreaks. We use as reference the U.S. Department of Agriculture Aerial Detection Survey (USDA ADS) records, focused on a small region in northwestern USA (Idaho). We compare the spectral differences over all visible and infra-red bands from MODIS and SENTINEL-2 for areas affected by bark-beetles and defoliators. We also analyze vegetation indices such as the NBR (Normalized Burn ratio) and NDVI (Normalized Difference Vegetation Index) for the years 2017 and 2018.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B53H2505R
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES