Research Objectives:
One of the central themes of the LTER (Long-Term Ecological Research) is to understand the transport of organic carbon throughout the ecosystem and one potentially large source of labile organic carbon that has not been investigated is the abundant small ponds found in most areas of the Dry Valleys, especially near the coast. The ponds have a relatively large surface area, and seem to generate a large amount of stranded microbial mat as they shift position on the landscape. The transient nature of these ponds renders the organic matter vulnerable to transport, which may be a significant source of modern, labile carbon to the other components in the Dry Valleys ecosystem. This project's objectives are to
+ Determine the extent of the coastal pond reservoir,
+ Assess how productive the reservoir is as a whole and
+ Determine if coastal pond reservoir is a source of sink within the organic carbon dynamics and overall structure of the terrestrial ecosystem in the Dry Valleys region.
Much of this work will focus on understanding the biogeochemistry of these ponds in terms of the factors affecting organic carbon production and nutrient cycling. Selected ponds will be instrumented to monitor surface evolution and annual temperature changes to determine the annual heat budget of the ponds and to determine if the ponds completely freeze to the bottom during the winter months. Pond sediments will be dated to place these features in a temporal context. The size of the coastal pond reservoir will be determined by enumerating the number of ponds in the region and by measuring the amount of organic carbon sequestered in selected ponds along with the productivity and biomass accumulation rates. The labile organic carbon content of the coastal ponds will be measured and incubation experiments will be conducted to investigate organic matter turnover rate within the ponds and surrounding soil environments.
This information will yield estimates of the residence time of this material in modern and relict ponds. The coastal pond organic matter will also be chemically and isotopically fingerprinted so that it can be identified within other ecosystem components to determine its significance to the overall ecosystem.
Project team members will establish camps along the Hjorth Hill coast and in the Garwood Valley. They will hike to the surrounding ponds and collect samples during the day and process the samples in the evening.
