Over the past decade, we have developed a conceptual model that documents the connectivity of glaciers (primary source of water) to lakes on the valley floor via stream channels. The stream channels provide two important functions beyond conveyance of water and associated solutes and energy to lakes – (1) they provide habitat for algal mats that include diatom and microbial communities, and (2) they accommodate active exchange of water between the channel and the hyporheic zone underneath and adjacent to the channel.
Wormherder creek is an ephemeral stream that occurs only during high flow. Located near Lake Bonney in Taylor Valley, in most years this hillside is bone-dry, making it an ideal site to investigate the long-term effects of extreme pulse/press events. The insert (left) shows an experiment that was flooded during the high flow of 2001-02 and 2008-09. We hypothesized that climate driven increases in the frequency and magnitude of high-flow events will lead to increased connectivity and subsequent redistribution of nutrients and biota across the landscape.
Climate warming in polar regions is associated with thawing of permafrost, resulting in significant changes in soil hydrology, biogeochemical cycling, and in the activity and composition of soil communities. While ongoing, directional climate warming can elicit such responses over decadal time scales, their manifestation typically occurs as discrete thawing pulses. Indeed, in the McMurdo Dry Valleys of Antarctica abrupt changes in community structure and biogeochemical cycling in terrestrial and aquatic ecosystems following a summer warming event (Jan.
The metacommunity concept is a major advance in ecology because it provides a theoretical framework to link ecological processes with biodiversity patterns at multiple scales. Metacommunities consist of assemblages of interacting species, typically linked over broad spatial scales by ecological processes influenced by spatial dynamics, environmental factors, and species traits. Diversity patterns in a metacommunity are thus influenced by niche-based species-sorting and dispersal dynamics.