Characteristics of respiration activation energy in black soil and its influence by plant species and soil collection location in Northeast China

• 1、Key laboratory of Forest Plant Ecology, Northeast Forestry University, Harbin 150040

Abstract：Soil respiration is an important part of the earth\'s carbon cycle, and the influence of soil on global climate is caused by CO2 emission from soil respiration. To date, limited data are available on the activation energy of soil respiration, and its association of sampling location and depths, land uses and tree species. This study collected 0-100cm soil from farmland shelterbelt (6 different locations) and Harbin Experimental Forest (8 stands) of Northeast China black soil area. The soil respiration activation energy (Ea) was calculated by the Arrhenius equation model on the basis of the soil respiration rate measured by incubation experiment. (1)The range of soil respiration activation energy in Northeast China is large, from 0.7 to 122.3 kJ mol-1, with an average value is 60.3 kJ mol-1, and the range of 95% confidence interval was from 58.7 to 61.8 kJ mol-1. Compared with other studies, Ea of black soil had a larger distribution range in China. (2) Forest types had marked different Ea. Larch forest\'s Ea ranged from 64.3-88.5 kJ mol-1, and lowest at oak forests (57.67-73.7 kJ mol-1). Larch forest\'s Ea was significantly higher than all other 7 forest types. This forest type\'s differences possibly related to functional groups of plants, i.e., the Ea of ECM type was higher than AM type but not up to statistical significance (P> 0.05); the Ea of coniferous forests was significantly higher than that in broadleaf forest by 6% (P < 0.05). (3) Ea of pooled 8 forest soils linearly increased with soil depths, however, poplar shelterbelts and farmland had a middle-depth lower Ea than the surface and deep soils. (4) Different land use types had a significant impact on Ea, and the Ea in farmland was significantly higher than that in poplar shelterbelt by 15.4%. In summary, unlike traditional simple chemical reactions with conservative and constant Ea, the Ea of soil respiration driven by microorganisms has a rather large range. Our data highlighted the importance of respiration Ea in understanding the stability of the soil carbon pool in northeast China from a chemical point of view, and the results could favor the "double-carbon strategy" via black soil carbon management.

Keywords： botany Arrhenius equation soil respiration activation energy forest type land use type