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An assessment of the effect of Sitka Spruce ( Picea sitchensis Bong. Carr) plantation forest cover on carbon turnover and storage in a peaty gley soil
Author(s) -
Ball T.,
Smith K. A.,
Garnett M. H.,
Moncrieff J. B.,
Zerva A.
Publication year - 2011
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.2011.01349.x
Subject(s) - gleysol , grassland , litter , environmental science , soil horizon , flux (metallurgy) , biogeochemical cycle , carbon fibers , nutrient , soil water , agronomy , forestry , chemistry , soil science , environmental chemistry , ecology , biology , geography , materials science , organic chemistry , composite number , composite material
We investigated carbon (C) incorporation and sources of C in the surface CO 2 flux at two sites in northern England on peaty (stagnohumic) gley soil, one afforested by Picea sitchensis , the other under continuous Molinia grassland cover. Radiocarbon ( 14 C) derived from atmospheric nuclear weapons testing was used to trace the incorporation of C into the soil and sources of C in the soil CO 2 flux from the soil surface and deeper layers. Larger values of 14 CO 2 in surface flux were found at the afforested site (109–110 per cent modern (pM) compared with 107–108 pM at the grassland site). Surface litter fractions (O i horizon) from the afforested site showed larger 14 C signatures than the equivalent fractions in the grassland (113–115 pM in the forest compared with 106–109 pM in the grassland). Fine root fractions (<2 mm, O e horizon) had similar signatures at both sites (109 pM in the forest compared with 109–111 pM in the grassland). Humified fractions at 10‐cm depth (O a horizon) showed smaller signatures (100–103 pM) in the forest than the equivalent fraction in the grassland soil (106–114 pM). According to a mixing model that takes into account pool size and 14 C signature, the contributions to surface CO 2 fluxes from slow turnover fractions that had resided in the soil for more than one year were greater at the forested site than the grassland site, but contributions from fast‐turnover C fixed within the year prior to study showed the opposite trend. The results, taken together with previous work indicating that both site preparation and clear‐felling lead to a net loss of C, indicate that long‐term fixation in deep soil organic fractions is limited on this soil type under plantation forest over 40–50‐year commercial rotations.