科研之友
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摘要
A 6-ha field at Aberystwyth, UK, was converted in 2012 from semi-improved grassland to Miscanthus x giganteus for biomass production; results from transition to the end of the first 3 years are presented here. An eddy covariance sensor mast was established from year one with a second mast added from year two, improving coverage and providing replicated measurements of CO2 exchange between the ecosystem and atmosphere. Using a simple mass balance approach, above-ground and below-ground biomass production are combined with partitioned CO2 fluxes to estimate short-term carbon deltas across individual years. Years one and two both ended with the site as a net source of carbon following cultivation disturbances, cumulative NEE by the end of year two was 138.57 +/- 16.91 g C m(-2). The site became a cumulative net sink for carbon by the end of June in the third growing season and remained so for the rest of that year; NEE by the end of year three was 616.52 +/- 39.39 g C m(-2). Carbon gains were primarily found in biomass pools, and SOC losses were limited to years one (-1.43 Mg C ha(-1) yr(-1)) and two (-3.75 Mg C ha(-1) yr(-1)). Year three saw recoupment of soil carbon at 0.74 Mg C ha(-1) yr(-1) with a further estimate of 0.78 Mg C ha(-1) incorporated through litter inputs over the 3 years, suggesting a net loss of SOC at 3.7 Mg ha(-1) from a 0- to 30-cm baseline of 78.61 +/- 3.28 Mg ha(-1), down 4.7%. Assuming this sequestration rate as a minimum would suggest replacement of cultivation losses of SOC by year 8 of a potential 15- to 20-year crop. Potential coal replacement per hectare of harvest over the three-year study would offset 6-8 Mg of carbon emission, more than double the SOC losses.
- 出版日期2017-1
