How does NASA play into Snapshot Wisconsin?

Astute contributors to Snapshot Wisconsin may have noted that one of the primary partners on the project is NASA. Yes, that NASA, known for space-flights and Neil Armstrong. For many people, the involvement of an air and space agency with a wildlife monitoring project may not be intuitive. Here’s how NASA and Snapshot Wisconsin work together:

NASA doesn’t just focus on our sun, solar system, and broader universe. It also has a dedicated Earth Science branch that houses research related to our atmosphere, weather, energy cycling, and ecosystems. This branch aims to predict change over time in, for example, energy cycling or biodiversity resources.

Some things, like animal population processes, are incredibly difficult to track across large spatial areas. Even with all the Snapshot Wisconsin cameras out on the ground, the total physical area in which we are observing animals is fairly limited – a point where each camera is, with a lot of space in between points. What we need to do is fill in the data gaps between camera locations. In other words, we need to be able to make predictions about areas where we don’t have observations. And this is where NASA comes into play.

NASA maintains a number of satellites that orbit Earth. These satellites carry on-board sensors that record light reflectance off of the Earth’s surface at different wavelengths. The images these satellites take of the Earth’s surface can be used to determine, for example, the locations of different landcover types (forest, wetland, prairie, etc.), or where leaves are growing or senescent, or where and when there is snow-cover. What’s great about these sensors is that they take photos regularly, and over large continuous spaces, so we can collect these data from our trail camera locations AND the spaces in between them.

Two of the more important sensors for our research are the Landsat and MODIS sensors. Landsat images have a spatial resolution of 30 meters (think of this as a pixel size – each pixel is 30 m by 30 m) and a temporal resolution (i.e., gap between flyovers) of 16 days. MODIS images have a spatial resolution of 250 – 500 m, and a temporal resolution of 1-2 days. These sensors are complementary—MODIS’s greater temporal resolution makes it more useful for detecting temporal environmental changes like plant green-up, while Landsat’s greater spatial resolution makes it more useful for detailed mapping of relatively static environmental attributes, like the location of forests, wetlands, and prairies.

Landcover maps of the same area derived from Landsat (left) and MODIS (right) satellite images. Modified from Schmidt et al. 2012.

How do we use satellite data and trail camera data together? We determine the association between the number of animals we count in trail camera photos and a series of environmental variables taken from satellite data. Understanding these associations gives us an idea of why animals might be more or less abundant in some places than in others, and allows us to suggest actions managers might take. For example, we might find that prairie chickens are highly associated with prairies but not with forests, and so we might suggest removing trees that are encroaching upon prairie land  in order to increase prairie chicken numbers.

Without images collected from space, it would be incredibly difficult to reliably predict and map the distribution and abundance of species.