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Arctic Biosphere Atmosphere Coupling at Multiple Scales

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Hypothesis 2: Topographic controls

Topography plays a critical role in the biogeochemistry of arctic regions through its influence on soil development, hydrology and microclimate (Shaver et al., 1996). There are clear spatial patterns in arctic vegetation distribution (see figure), and we expect that close links between soil and vegetation processes will lead to similar correlation length scales. Correlation lengths provide an estimate of the size of homogeneous units of soil and vegetation, and a means to identify boundary zones. We expect that topography governs the size of these functional units, through controls on hydrology. Thus, soil moisture correlation lengths will be closely connected to vegetation/soil correlation lengths.


Figure legend. Spatial correlation (R) between 5 m resolution normalised difference vegetation index data collected at various densities from a 500 x 500 m grid on tundra near Abisko. The correlation between data weakens with increasing separation; the correlation length was ~40m, as calculated by fitting these data to a model. Unpublished data from R. Bell and M. Williams.

H2: The key length scales which govern the distribution of plant C, soil C and soil moisture are correlated throughout the landscape.

WPs 2, 5 and 6 will generate spatial surveys of soil C, soil moisture, vegetation type and LAI, and digital elevation models (DEM) from remotely sensed imagery from the aircraft and satellites. WP4 will generate continuous measurements of soil moisture at points throughout the study regions. WP7 will generate spatio-temporal predictions of soil moisture linked to topography for testing against data.

Outcome: DEMs and remotely sensed images of vegetation cover can be used to generate maps of soil C with confidence intervals. Improved landscape soil moisture models.

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Last modified: 27 Jan, 2006
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