Characteristics of soil greenhouse gas flux and its driving factors in Horqin sand dune-mea-dow wetland cascade ecosystems.

Abstract

Using the static chamber-GC technique, greenhouse gas (CO2, CH4, N2O) fluxes of sand dunes and meadow wetlands were measured in a typical sand dune-meadow cascade ecological zone of Horqin. The dynamics of the greenhouse gas fluxes and driving factors were analyzed. The results showed that soil CH4 flux underwent absorption during the growing season, with average CH4 fluxes of semi-mobile dunes and meadow wetlands were -52.7 μg·m-2·h-1 and -34.7 μg·m-2·h-1, respectively, ranging from -176.1 to 49.8 μg·m-2·h-1. The peak of CH4 absorption in the growing season occurred at August 22nd, 2017. In August and September, the months with heavy rainfall, the CH4 flux in meadow wetlands showed continuous emission, being significantly different from that in semi-mobile dunes. The peak of N2O flux during the growing season was at July 21st. The monthly average N2O flux in semi-mobile dunes was following the order of July > August > September > June > May. Soil temperature and moisture were the key factors affecting CO2 and CH4 fluxes, whereas the N2O flux was mainly affected by soil temperature. The soil temperature sensitivity (Q10) showed the sequence of semi-mobile dune (1.009) < meadow wetland (1.474). The water stress rendered the greenhouse gas fluxes in semi-mobile dunes being less sensitive to soil temperature change than that in meadow wetlands.