水保所知识产出(1956---)知识库

Re-vegetation of cropland is an important measure for carbon (C) sequestration, while the combined effects of
land-use change, re-vegetation type and time on soil organic C (OC) turnover and temperature sensitivity have
been less studied. Here, we investigated soil cumulative OC mineralization (C min ), specific OC mineralization
(C min /C 0 , normalized by initial OC) and temperature sensitivity (Q 10 ) with an 84-d incubation experiment after
the conversion of cropland to artificial grassland (6, 10, 15 and 20 yr), to natural grassland (6, 10 and 20 yr) and
to pea shrub woodland (10, 20 and 40 yr) in the agro-pastoral ecotone of northern China. Results showed that re-
vegetation significantly increased C min (from 38.21 to 57.79 mg kg −1 soil, +51%) at the 0–10 cm depth but not
the 10–20 cm depth, with greater increases after the conversion of cropland to artificial grassland (+77%) than
the other two patterns but similar among different conversion years for each pattern. Variations in C min among
different re-vegetation patterns and times were mostly explained by changes in total nitrogen concentration (TN)
in the macro-aggregate fraction. Across all treatments, 6.20–20.29 g kg −1 OC was mineralized during the in-
cubation and Q 10 was 1.16–2.40. The C min /C 0 and Q 10 changed not significantly during the post-agricultural re-
vegetation chronosequences for each pattern, which were mostly due to the unchanged TN concentration in silt
and clay fraction. Re-vegetation also changed the dependence of C min , C min /C 0 on N availability, with significant
relationships in re-vegetated artificial grassland and pea shrub woodland which may due to the influence of
legumes on microbes. In conclusion, OC mineralization increased with conversion, varying by re-vegetation type,
while OC decomposability and temperature sensitivity were stable regardless of re-vegetation type and time,
indicating the similar biodegradability and stability in face of warming.