Spatial scaling of CO2 efflux in a temperate grazed grassland

Archer, Nicole A.L.; Rawlins, Barry G.; Marchant, Benjamin P.. 2014 Spatial scaling of CO2 efflux in a temperate grazed grassland. [Poster] In: EGU General Assembly 2014, Vienna, Austria, 28 Apr - 2 May 2014. British Geological Survey. (Unpublished)

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Understanding CO2 efflux from soil at different scales is important when up-scaling CO2 measurements from plot to larger scales, but there have been few studies investigating spatial CO2 efflux in temperate environments. We conducted a nested analysis of variation to explore how the CO2 efflux variation occurs between different spatial scales. Ninety-six manual dynamic chamber flux measurements of CO2 were undertaken during three, four hour surveys within seven grouped sites, each containing an optimised nested design with lag distances of 0.3m, 1m, 3m and 9m across six hectares of grazed hillslope grassland. This design also included continuous logging soil moisture sensors (plus conductivity and temperature) at 10cm soil depth. A previous study showed at this site that the variation of soil moisture is divided relatively equally between the four spatial scales <0.3m, 0.3-3m, 3-9m and >9m. The proportion of large-scale (>9m) variation increased after rainfall. In contrast in the three surveys analysed to date, the vast majority of the variation in CO2 flux occurred over the two smallest scales. No significant correlation between CO2 and soil moisture was observed over any of the spatial scales. All of these three surveys were conducted on relatively dry soils. We also investigated whether there were significant temporal variations in CO2 efflux over a period of three weeks using an automated soil flux system. These data showed there was no significant temporal variability between 10:00 to 16:00 hrs during late summer. There has recently been substantial rainfall at the field site and we are now conducting additional surveys to examine how the total CO2 fluxes and their spatial variation is effected by these wetter conditions.

Item Type: Publication - Conference Item (Poster)
NORA Subject Terms: Agriculture and Soil Science
Atmospheric Sciences
Date made live: 05 Nov 2014 14:48 +0 (UTC)

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