An interesting part of the field course for me has been learning about topics that are not part of my primary discipline. While Jess and Chelsea are well versed in the area of ecology Ali, Lee and I are newcomers to the field. Throughout our week camping we learned a few principles of ecology including the brown and green food webs and biodiversity. Learning new material while immersed in Greenlandic tundra was an amazing hands-on experience that I’m sure I will never forget. In the following, I will go into greater detail about the ecology we learned.
The Brown and Green Food Webs
The green food web is the food web that I automatically think of when I hear the term. It consists of plants and the animals that eat them and makes up about 10% of the total biomass. Two of the keystone species in Western Greenland are dwarf birch (Betula nana) and the willow (Salix glouca).
Photo of Betula nana
Some of the other species that one frequently sees in the Greenlandic tundra are the blueberry, musk ox, caribou, arctic fox, arctic hairs, and various grasses and sedges. Another fun species that Matt showed us is the Dryas integrafolia a close relative to the species whose pollen is found in lake cores from the cold Younger, Older, and Oldest Dryas periods.
The brown or decomposer food web consists of dead plants and animals and the various organsims that decompose them. The brown food web makes up the other 90% of total biomass. The brown food web recycles nutrients and makes them available for the organisms of the green food web to utilize.
Biodiversity of the Arctic
To develop a better understanding of the term biodiversity we set out from camp and hiked up a hill relatively close to the edge of the ice. Once there, we all spread out and found a one meter by one meter patch of land to exam. The purpose of our close examination of such a small area was to count as many different types of plants that we could see. I saw 12 different types of plants in my plot including but not limited to blueberries (Vaccinium uligonosum), dwarf birch (Betula nana), pussy willow (Salix glouca), one mushroom, three flowering plants, two types of lichen and some moss.
Two flowers from my plot
Once everyone had totaled up all the plant life they saw in their plot we gathered back together to compare notes. The average number of species identified by each person in the group was 11.2. At this point Matt Ayres told us that he has conducted this same experiment multiple times in the high altitude regions of Costa Rica and the average number of species seen by that group was only 9.4. What was going on?
Isn’t it true that the tropics have the highest diversity on the planet? Could the tundra really have more diversity? The answers to these questions come in learning about alpha and beta diversity. Alpha diversity is a measure of the average number of species in a given area from multiple plots while beta diversity is a measure of total species found in all of the plots examined. So while the Greenlandic tundra was higher than the Costa Rican highlands in alpha diversity it is significantly lower in beta diversity; ie. the total number of species present in the Arctic tundra is significantly lower than the total number of species found in the highlands of Costa Rica.
Jess and Ross examining the species present on the hillside with an awesome view of the ice sheet.