efficient and accurate counting of wildlife populations.
The National Aeronautics and Space Administration (NASA) is also part of this trend. In 2019, it plans to launch a mission called GEDI (the Global Ecosystem Dynamics Investigation) using lidar, a laser-based remote sensing technology already familiar to ecologists for mapping 3-D vegetation structure from airplanes. This time, from the International Space Station, GEDI will enable scientists to determine the height and structure of the forest in any given location and precisely map above ground biomass and carbon storage — all without applying for grants to hire an airplane or spending days flying transects.
GEDI will also make it possible, according to the University of Maryland’s Ralph Dubayah, principal investigator on the mission, “to estimate the net impact of deforestation and subsequent regrowth of forests, and to provide information critical for preserving and promoting habitat quality and biodiversity.” The technology should prove useful for monitoring commitments made by nations under REDD (the program to reduce emissions from deforestation and forest degradation) as well as under the Paris climate accord and the Convention on Biological Diversity. In addition, it will improve weather and climate modelling and provide detailed measurement of temperate glaciers, lakes, and rivers for better management of water resources.
A University of California scientist describes the rapidly improving satellite view from outer space as a “macroscope.”
Ecologists “are going to have this epiphany,” says David Johnston, as they begin to understand the potential of these new tools. It happened for him a few years ago while giving an undergraduate lecture about the movements of radio-tagged seals on Cape Cod. “We have tags on live animals, and it’s really great for students,” he says. “They can check in every day on where a particular seal is traveling. I was loading data on Google Earth, and just zoomed right in to see where this seal turned up, and lo and behold, the image was good enough to count seals on the beach. I looked and said, ‘Hey, we could probably count the Cape Cod seal population this way,’ and at the end of class, three students came up to say they’d like to do that.”
The seals commonly use beaches as summertime “haul-outs,” and in the past, the National Oceanic and Atmospheric Administration (NOAA) has counted them in the traditional fashion, by flying over the beach and taking photographs. But NOAA never got around to publishing all the resulting data, to the frustration of other researchers, says Johnston, and it also “never worked to correct the beach count for the number of animals at sea.” Satellite images freed the researchers from dependence on the NOAA data. And data from their own long-term radio-tagging study, showing how much time seals spend typically at sea in a given day or season, allowed the researchers to develop an algorithm for calculating the total population, rather than just the part visible on the beach.
Douglas McCauley, a marine biologist at the University of California Santa Barbara, praises the new study for bringing the potential of satellite-based wildlife research “home to our own backyards,” on a question with major management implications. For Cape Cod vacationers feeling that a seal haul-out has crowded them off a favorite beach, or for fishermen losing their catch to seals, news that there are now 50,000 gray seals on the Cape is likely to sound like an invasion. For conservationists, on the other hand, it may not even represent recovery to the original population level. The long-running debate about the seals can become highly emotional. An accurate count is the essential starting point for deciding among such management options as keeping hands off, paying for a contraceptive darting program, authorizing nonlethal harassment, or even beginning to cull seals. “This is placing satellite data front and center in wildlife management,” says McCauley.
Beyond counting populations, satellites also have the potential to answer bigger wildlife behavioral questions. McCauley’s lab is using satellite data, for instance, to determine how
news
Grassroots
August 2017
Vol. 17, No. 3
42