Field research may seem glamorous -- exotic places like the Alaska wilderness, timely science that help solve natural resource management questions -- but certainly, field ecologists have to endure Nature and her elements in full to collect the samples that help solve these questions.
For you field blogging junkies out there, check out the Alaska Maritime 2011 Field Season blog
set up by the Alaska Maritime National Wildlife Refuge
. The blog provides little glimpses of all the different government and university research projects that take place far out in the remote reaches of the Aleutian Islands
-- in the heart of the Bering Sea.
Wildlife biologist Mark Ricca
of the WERC Davis Field Station
is currently at the Refuge on Adak Island
. Ricca is studying the impact of non-native caribou
on the local ecosystem as part of his doctoral research at the University of California, Davis, under advisor Keith Miles
In a quick email back home, Ricca
explains why caribou -- even though a native of mainland Alaska -- can be harmful to an isolated island ecosystem:
Adak Island is a large (732 sq. km.) mountainous island located in the central Aleutian archipelago, and was an active military installation from WWII through the conclusion of the Cold War. In 1958, 23 barren-ground caribou from the Nelchina herd on mainland Alaska were transplanted to Adak at the request of the U.S. Navy for food and sport. The resulting population grew to a stable populations size of approximately 300 – 600 animals until the former Naval Air Facility was decommissioned in the early 1990s.
Hunter harvest declined dramatically with the closure of the naval base on the island in 1993, which contributed to an exponential increase to about 2800 animals by 2005. Thus, this growing population of introduced caribou on Adak Island presents a challenging management dilemma owing to a lack of current information regarding their impacts on island ecosystem function.
Moreover, as forage resources on Adak become depleted, the potential for caribou emigration to nearby neighboring islands represents an additional concern. While high caribou densities likely result in ecosystem degradation on a spatially limited island, herbivory by caribou at low intensities may stimulate the production of graminoid grasses and increase soil nitrogen availability -- a significant change for nutrient-limited systems such as the Aleutians.
Results from 2010 indicated increased grass cover, decreased dwarf shrub and lichen cover, and potential increase in plant-soil nitrogen in areas of low caribou use, versus a depletion of plant and soil nitrogen in high caribou density areas. In 2010, we sampled Adak as the caribou island and Kagalaska as the reference island for comparison.
This year, we are continuing our plant and soil surveys on Adak along with collections of caribou scat to determine diets, and will also sample Atka Island to the east (an island with introduced reindeer since the the early 1900's) and other non-caribou reference islands.
You can read more snippets of Ricca's trials and experiences on Adak Island at the blog, as his team observes caribou calves and mothers, searches for caribou dung and tracks, and battles thick fog and the whims of the weather through to September.
-- Ben Young Landis
Top Image: Adam Duarte of Texas State University, Mark Ricca of USGS and Butch Weckerly of Texas State University work together to study the caribou of Adak Island. Image courtesy of Alaska Maritime NWR.