By Harish Anandhanarayanan Mentor: Dr. Alfredo Huete

The problem to be tested is to theoretically show the effect of deforestation and how it leads to increased forest fires as stated in the article to the left. In order to show the relationship between deforestation and forest fires, satellite data from MODIS will be used in two different areas in Brazil Tapajos National Park – Preserved Forest Area Pasture region – deforested area outside Tapajos National Park Source:

MODIS or Moderate-resolution Imaging Spectroradiometer is a scientific equipment that was installed in the satellite Terra, launched by NASA in 1999 and Aqua, launched by NASA in 2002 Aqua and Terra contain many other equipments, for measuring atmospheric temperature, humidity etc., but are the only two satellites in space right now that carry MODIS MODIS helps image the earth every 1 to 2 days, and sends data in terms of surface temperature, atmospheric temperature and vegetation on the planet. In order to get data for deforestation, Vegetation Indices (NVDI, EVI) from MODIS will be used in order to see vegetation growth trends in the two sites in Brazil Source:

NVDI and EVI are measured values of density of plant growth over the entire planet NVDI and EVI utilizes the wavelengths of visible and near infrared sunlight reflected by the plants Chlorophyll, a pigment in plants, strongly absorbs visible light (0.4 to 0.7 μm), while the structure of the leaves strongly reflect near infrared light (from 0.7 to 1.1 μm) ‏ In general, if more near infrared light is reflected than visible light, then there is more chlorophyll and the vegetation is dense, while very little difference indicates vegetation is sparse (grassland, tundra, desert) ‏ EVI (Enhanced Vegeatation Index) is a cleaner and improved measurement compared to NVDI, since many particles such as aerosol and cloud covers are corrected, but both are calculated similarly to measure vegetation. Source:

Methods In order to do analysis, first data has to be obtained from MODIS website* for a particular site One can choose a list of sites that data has already been obtained One can also choose any site around the world with a particular window size Then using Excel, import the data related to EVI/NVDI (Vegetation Indices) and analyze using statistical tools or graphical tools provided in Excel Compare the results obtained to physical changes associated in the area tested * (Oak Ridge National Laboratory)

Santarem – Km 77 – Tapajos National Forest (Pasture) ‏ Source: Google Earth

The results show that forests region in Tapajos National Park, that are relatively untouched, have an increased growth rate in the dry season, and lower growth in the wet season. Also it shows that the pasture region, that are due to deforestation, have an opposite effect, where there is increased growth rate in the wet season, and lower growth in the dry season. This is due to the fact that large trees in the forests have long and large roots, so it does not dry up as fast as the pastures, but enjoy the long periods of sunlight in the dry season, while the pastures tend to dry up quickly, due to their shallow roots, and enjoy the rain that keep the roots moist in the wet season. This gives some insight on why there is an increased rate of forest fires in forests that have pastures, as opposed a plot with uninterrupted forest, since the dry pastures are more susceptible to fires in the high heat, while forests remain moist and wet in the dry season and have increased growth that lead to a lower chance of forest fires.

According to the article, using MODIS, conversion of tropical forests to cropland has a drier effect as opposed to conversion of tropical forests to pastures which have a cooling effect. But according to our results, even the conversion of tropical forests to pastures have a significant effect on the growth of the plants in the region and lower plant growth in the dry season. According to the results, any conversion of tropical forests using deforestation, have a significant effect on the region, especially increased forest fires that have implications economically and in terms of global warming Most forest fires in Brazil are due to neighboring pastures and croplands next to the forests, that dry up and spread the fire into many regions in the Amazon, thus destroying much of the region. Even though many areas of Brazil is untouched and preserved, recent forest fires in Brazil and increased deforestation suggest, the Amazon is being threatened, and from the significantly increased forest fires in many countries in Asia, like Indonesia, due to accelerated deforestation, the Amazon, that receives 2/3 of the rainfall in the world, is in danger of disappearing. Also MODIS, provides great insights into the effects due to climate change and vegetation. It is an useful tool in analyzing many regions in the world especially in terms of vegetation changes.

Any Questions?

Different ways to visualize Vegetation Indices

Source:

Burning and deforestation of the Amazon forest to make grazing lands Using MODIS, tan areas show deforestation and the green areas show the Amazon