McMurdo Dry Valleys Long Term Ecological Research (LTER)  
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  McMurdo LTER Hypotheses for MCM-III

Central Hypothesis:

Biodiversity and ecosystem structure and function in the MCM are dictated by the interactions of climatic legacies with contemporary biotic and physical processes.

This hypothesis will be addressed within three distinct but integrated scientific portfolios:

  1. Hydrology
  2. Biodiversity
  3. Ecosystem structure and function

Portfolio 1 - Hydrology

  • Hypothesis 1a. The variability of glacier melt depends on the interaction of climate and landscape position, and sediment on the glacier surfaces.
  • Hypothesis 1b. Meltwater in interconnected subsurface passages on the glaciers creates cryoconite habitats, and biological processes in these habitats influence aquatic geochemistry throughout the MCM.
  • Hypothesis 1c. At the stream/soil interface, thawing of the active layer in summer drives the expansion of the hyporheic zone, increasing storage of water, solute flux from weathering reactions and microbial cycling of nutrients in the streams.
  • Hypothesis 1d. Spatial variation in the hydrologic characteristics of the hyporheic zone creates a mosaic of biogeochemically heterogeneous subzones.

Portfolio 2 - Biodiversity

  • Hypothesis 2a. Stream and lake microbial mats provide seed populations to the contemporary MCM landscape.
  • Hypothesis 2b. Diversity of stream microbial mats is controlled by flood frequency, streambed stability, and small-scale patchiness related to hyporheic exchange.
  • Hypothesis 2c. The diversity of soil invertebrate communities is determined by soil legacies and hydrology.
  • Hypothesis 2d. Phytoplankton diversity is controlled by a combination of “old” nutrient input via diffusion from below the chemocline and “new” nutrient input from streams.

Portfolio 3 - Ecosystem Structure & Function

  • Hypothesis 3a. Biodiversity in all landscape units is linked to ecosystem functioning (diversity begets function). Higher diversity is associated with greater C, N and P cycling.
  • Hypothesis 3b. Biogeochemical activity, nutrient deficiency, and biodiversity relationships within the MCM landscape are reflected in the elemental stoichiometry.
  • Hypothesis 3c. The low biodiversity and slow growth rates of its organisms make MCM ecosystems highly susceptible to local and global human disturbance.
  • Hypothesis 3d. Geomorphological features interacting with resource legacies of landscape units dictate the distribution of species and ecosystem function.

Read more details in our 2004 research proposal

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Last updated Winter 2012
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