Original Excercise: http://www.esa.int/SPECIALS/Eduspace_Global_EN/SEM94FNW91H_0.html
Vegetation in South America
Forests occupy approximately 22% of South America, and represent about 27% of the world’s global forest coverage. They play an important role in the carbon budget (i.e. the contribution of carbon dioxide on the planet) and in the economy of Latin American countries, as well as other parts of the world.
Deforestation of the Amazon rainforest is having a negative impact on the planet because it reduces rainfall and provokes runoff losses, reducing water input in various regions such as Brasil, Venezuela and Bolivia. If precipitation decreases in South America, other countries that depend on its economical activities (e.g. rangelands) could be affected. A reduction in rain can lead to a drought, which can cause livestock production to drop drastically.
Mountain ranges and plateaus conserve the biological diversity and unique ecological state of the river. There are glaciers in the high Andes (Venezuela and Peru) and three major ice sheets in the Patagonian Andes. Climate change and the ENSO phenomenon in particular can modify the rate of snowfall and runoff in areas of piedmont. Approximately 35% of the world’s continental water is found in this continent.
Agricultural land makes up 19% of the land area in South America. Agriculture is a key sector in South America’s economy because 40% of the active population works in the fields. The main crops are barley, grapes, maize, potatoes, soybeans, wheat, sugarcane and coffee.
All of the world’s major types of ecosystems are present in South America. Venezuela, Colombia, Ecuador, Bolivia, Brasil and Peru are among the richest countries in terms of plant and animal species. Forest biomes in this region include tropical rainforests like the Amazon and the Mata Atlantica in Brasil. Other tropical deciduous forests can be found in the Pacific watershed of Ecuador, in Venezuela, and on the Brasilian coast from about 7°S to the Tropic of Capricorn. Mid-latitude deciduous or temperate forests are located on low elevation coastal mountains in southern Brasil, southern Chile and southern Argentina. It is possible to find Austral forests on the southernmost tip of the continent and on Tierra de Fuego Islands.
The most extensive ecosystems are grasslands, shrublands and deserts, which can be found on the Caribbean coast of Venezuela, north-eastern Brasil, and inland areas between Brasil and Bolivia.
Mid-latitude grasslands occupy areas in southern Brasil, Uruguay and central and eastern Argentina. Tropical grasslands and savannahs are present in Central America, the Guyanas, Venezuela, Colombia, Brasil, Paraguay and Argentina. Arid shrublands occupy the west of Argentina and Patagonia, and hyper-arid areas exist along the west coast of Peru and northern Chile, as well as in southern Bolivia and north-western Argentina.
Exercise 1: LAI - Vegetation from space
Vegetation can be monitored from space with the help of satellite sensors. These sensors produces images with multiple bands that correspond to wavelengths in the electramagnetic spectrum. From these wavelengths, a vegetation indicator such as the Leaf Area Index can be calculated. LAI is recognized as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS), and is provided by the Copernicus Global Land Service: https://land.copernicus.eu/global/products/lai
This data can be visualized directly in the Terrascope Viewer. Follow the link below to compare the difference between two seasons in 2018, so you will be able to answer the quiz at the bottom.
Vegetation is affected by precipitation levels. Compare the two images below using the slider to evaluate differences in vegetation:
Exercise 2 : NDVI Animation
The main objective of this exercise is to create an animation of the vegetation dynamics for the whole South American continent.
The Terrascope viewer provides an interface to create an animation. Follow these steps:
- Navigate to https://viewer.terrascope.be and find the Copernicus Global Land LAI Layer.
- Click the 'export' button, and choose 'timelapse'
- In the timelapse panel, choose the desired dates. For instance select a full year.
- Now you can choose 'select all' to add all images for those dates to the timelapse.
- The timelapse will be generated, this can take some time.
- Use the 'download' button to download a gif animation.
When succesfull, the result should look like this:
Exercise 3: NDVI dynamics by biogeographical zones
For this exercise, we will use a Jupyter notebook to do an analysis of PROBA-V NDVI data. Read more below.