Soil carbon sequestration in sand-fixation plantation of Pinus sylvestris var. Mongolica and response of soil respiration to drought and wet conditions

Background/Question/Methods

The Horqin Sandy Land is located in the agro-pastoral transitional zone between the Inner Mongolian Plateau and the Northeast Plains of China (42°41' to 45°15' N, 118°35' to 123°30' E), and is one of the most seriously desertified regions of China. To control desertification and reduce its influence, some successful measures, including fencing sandy rangeland; planting indigenous trees, shrubs and grasses; and placing sand arresters (straw checkerboards), have been implemented in parts of the Horqin Sandy Land since the mid 1970s. The objective of this paper was to investigate soil carbon sequestration of sand-fixation plantation and the response of soil respiration to different water condition in woodland and mobile sand dune.

Results/Conclusions

Results show that (1) after 23 years since Pinus sylvestris var. Mongolica was planted in mobile sand dune, the content of very fine sand and silt + clay increased significantly in soil, whereas soil bulk density decreased; (2) soil organic carbon sequestration in woodland was 221.8 and 113.9 g·m^-2 at the depth of 0-5cm and 5-15 cm, respectively, whereas sequestration rate was 9.64 and 4.95 g·m^-2·y^-1; CaCO₃-C sequestration was 4.0 and 2.5 g·m^-2 and the rate was 0.17and 0.11 g·m^-2·y^-1; (3) during drought period, soil respiration showed a strong negative exponential relationship with air temperature; soil respiration in woodland was higher than that in mobile sand dune whether the condition is drought or not; and (4) soil respiration increased after the rain, but the increment was higher in woodland; the removal of surface litter resulted in decrease of soil respiration and rain exacerbated the difference.