My name is Nathalie Pettorelli, I am a research fellow at the Institute of Zoology, Zoological Society of London. My project aims at exploring how satellite data can help monitor ecosystem responses to changes in climatic conditions, by providing information on vegetation dynamics.

Vegetation is the main component of the terrestrial biosphere and represents a crucial element in the climate system. From the perspective of understanding and predicting the impacts of climate change on biodiversity and other ecosystem services, being able to monitor changes in vegetation across the globe ranks high.

For decades, vegetation monitoring has been carried out by sending people in the field. The problem with this is that field data are generally difficult to use for assessing how climate change might affect vegetation, because such data are traditionally collected at small spatial and temporal scales and vary in their type and reliability.

With data collected at the scale of the Earth and monitoring programs that started in the seventies, satellites offer a great possibility to carry out long-term monitoring of vegetation, at scales spanning from a few meters up to regional or continental scales. As an example, here is a picture of the sunderbans, taken by a satellite called Aster.

My project focuses on one type of vegetation indices derived from the information collected by satellites: the Normalized Vegetation Difference Index (NDVI), which is a measure of greenness. To illustrate the type of information I use, a map presenting “greenness” values for Europe in March 2011 is shown above: the greener it appears on the map, the greener it is on the ground.

My work currently focuses on protected areas (such as the Ngorongoro Crater, above) and consists in identifying those areas where patterns of vegetation dynamics and distribution have significantly changed. Land-use conversion is minimized in protected areas, therefore assessing changes there can help discern the effects of different drivers of environmental change on ecosystem functioning.

NDVI offers a wealth of opportunities for environmental monitoring. Regular information on the state of the vegetation can for example help predict drought, monitor their impact on ecosystems and inform vegetation recovery process

What’s also interesting with NDVI is that it can be linked to animals. Satellite-based information on the level of greeness can for example help predict the abundance of large herbivores (such as elephants in Africa).

Information on vegetation phenology derived from satellites can also help predict bird migration patterns.

All in all, I believe satellite imagery is a goldmine for ecologists and conservationists, providing a fantastic opportunity to help monitor ecosystems and their response to increased anthropogenic pressure.

Image 1 of 10

Image 2 of 10

Image 3 of 10

Image 4 of 10

Image 5 of 10

Image 6 of 10

Image 7 of 10

Image 8 of 10

Image 9 of 10

Image 10 of 10