Trisha Atwood, Ecosystem Ecologist
An Ecosystem with Geese
Trisha Atwood says there are about 200 species of birds that at some point will use the YK Delta in some part of their life cycle. It might be a resting stop, or foraging, or a breeding site for them. The geese that Atwood’s group is studying like the Cackling Geese, the White Fronted, or the Black Brant, are using the Delta as a nesting site. The geese come in the Spring and lay eggs and raise the young geese to the point where they can fly South again.
Geese are Gardening
“When the geese don’t show up,” Atwood explains, “we don’t get grazing lawns. Grazing lawns are where the geese clip, and they trample on the grass, and they poop on it.” “We actually get a carrex, a grass, that looks very different in structure. So it looks very very short, it gets this flower or Rosetta pattern to it, and it is really, really high in nutrition. So it is almost like the geese are gardening. They are trying to keep this highly nutritious version of the plant going.”
Ecosystem Differences
Atwood adds, “When the grass is long, it doesn’t have as many nutriments like nitrogen, phosphorous, and carbon that go into the soil to help stimulate microbial communities. When the microbial communities get less nutriments, there is less CO2 and Methane emissions in the salt marsh.
Carbon Quantity or Quality
One of the major questions in science right now for microbial communities, according to Atwood, is, Is it quantity or quality? Some people say, as long as you have enough carbon, even crappy carbon, microbes can build and emit tons of CO2 and Methane. Other people say it is quality that matters, you have to have really good carbon for these microbes to produce the CO2 and Methane.
“And that separates the difference between the grazing lawns and the meadows,” Atwood says, “because in the grazing laws you have the good carbon but not very much of it, and then in the meadows you have crappy carbon, but tons of it.”
Humans and Animal Influences on Ecosystems
Atwood describes, “Animals can affect three aspects of carbon. It can affect its accumulation, it can affect its retention, and it can affect what the product is. Is it CO2, Methane, or does it get stored in the soils as organic carbon. So animals can influence the whole aspect of the carbon cycle that human are interested in.”
