Reconstruction of Ecological History

Using the past to inform the present and the future

Historical perspectives are valuable for answering a host of questions about the origin of present-day park ecosystems and for providing context for the interpretation of information that will arise from future monitoring.

Ecological records can include information from library archives, such as photographs from a turn-of-the-century expedition. It can also include records left behind in nature, such as those recorded in tree rings and lake sediments.

Photographic Monitoring of Landscape Change

Repeat Photography Description
Repeat Photography Search Tool

Repeat photography provides an efficient and relatively inexpensive method for documenting change on the landscape. Historical photographs can extend the period of monitoring to a century or more and can serve as the basis for hypotheses that support more intensive measurements. Repeat photography is also an excellent method for communicating change to a broad audience. Torre Jorgenson, ABR, Inc., has compiled over 200 photo pairs for the SWAN that illustrate the range of changes that have occurred on the landscape over the past 100+ years.

Time-series of satellite imagery can also be used to detect changes on the landscape over a broad spectrum in time from multi-year shifts in glacier extent and vegetation to daily changes in ice cover.

Paleolimnology

Paleolimnology is the study of past freshwater, saline and brackish environments. Lake sediment cores provide clues as to the ecological history of a lake and its surrounding environment. Dr. Bruce Finney, Idaho State University, has analyzed lake cores from Lake Clark, Katmai, and Aniakchak to reconstruct past changes in salmon abundance and lake primary productivity. He has compared these reconstructed changes to records of past environmental change to determine how factors such as climate, volcanic eruptions, geomorphic change and human impacts influence freshwater systems of the SWAN. Dr. Patricia Heiser, University of Alaska Anchorage, has likewise analyzed lake sediment cores from Lake Clark and Katmai to estimate the timing of deglaciation, the timing and degree of lake level changes, the age of volcanic ash deposits, and the arrival of different vegetation types following the Last Glacial Maximum.

Dendrochronology

Dendrochronology is the dating of past events through the measurement of tree rings. Tree-ring data can provide information regarding climate or disturbance regime (e.g., fire, insect outbreaks). Recent spruce beetle outbreaks in southwest Alaska have resulted in extensive forest mortality. To investigate whether such large outbreaks occurred historically, Drs. Rosemary Sherriff, University of Kentucky, and Ed Berg, USFWS Kenai Wildlife Refuge, have collected tree cores from a total of 15 sites in Lake Clark and Katmai. Results to date suggest that regional outbreaks have occurred in the past (e.g., late 1800s), but questions remain as to what environmental factors could trigger such an event.