Dou Wei-Qiang, Xiao Bo, Wang Yan-Feng, Jiang Zi-Hao, Yu Xing-Xing, Li Sheng-Long
College of Land Science and Technology, China Agricultural University/Key Laboratory of Arable Land Conservation in North China, Ministry of Agriculture and Rural Affairs, Beijing 100193, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2022 Jul;33(7):1783-1790. doi: 10.13287/j.1001-9332.202207.009.
The changes in soil properties caused by grazing and trampling are important reasons for the changes in soil respiration rates, carbon fixation, and emission. However, the effects of different intensities of grazing and trampling on biocrusts respiration rate are unclear. In this study, we simulated grazing and trampling disturbances of 10%, 30%, 50%, and 70% intensity on moss biocrusts developed in aeolian sandy soil on Loess Plateau, with undisturbed moss biocrusts serving as a control. The changes in respiration rate of moss biocrusts were monitored continuously, and its responses to different disturbance intensities were analyzed. The results showed that: 1) moderate disturbance stimulated moss biocrusts respiration, while heavy disturbance inhibited that. The respiration rate of moss biocrusts was increased by 41.1% and 22.2% at disturbance intensities of 10% and 30%, but was decreased by 8.9% and 15.3% at disturbance intensities of 50% and 70%, respectively. 2) The trampling disturbance significantly changed soil temperature but did not affect soil water content. In comparison to the control, soil temperature of biocrusts was decreased by 0.4 and 1.2 ℃ at disturbance intensities of 10% and 30%, but it was increased by 1.1 and 1.0 ℃ at disturbance intensities of 50% and 70%, respectively. 3) The respiration rate of moss biocrusts showed a significant exponential relationship with soil temperature and a linear positive relationship with soil water content under different disturbance intensities. However, the correlation between respiration rate of moss biocrust and the characteristics of moss biocrust was not significant. Soil temperature and water content could explain 70.6%-96.3% and 49.1%-70.0% of the total variation of respiration rate of moss biocrusts, respectively. In conclusion, grazing and trampling affected the respiration rate of moss biocrusts, with short-term moderate grazing and trampling would have positive effects. On the other hand, excessive grazing and trampling would reduce the rate of moss biocrust respiration. As a result, future studies on soil carbon balance of the Loess Plateau should consider the effects of grazing and trampling on biocrust respiration.
放牧和践踏引起的土壤性质变化是导致土壤呼吸速率、碳固定和排放变化的重要原因。然而，不同强度的放牧和践踏对生物结皮呼吸速率的影响尚不清楚。在本研究中，我们模拟了黄土高原风沙土上发育的苔藓生物结皮10%、30%、50%和70%强度的放牧和践踏干扰，以未受干扰的苔藓生物结皮作为对照。连续监测苔藓生物结皮的呼吸速率变化，并分析其对不同干扰强度的响应。结果表明：1）适度干扰刺激苔藓生物结皮呼吸，而重度干扰则抑制呼吸。在10%和30%的干扰强度下，苔藓生物结皮的呼吸速率分别增加了41.1%和22.2%，但在50%和70%的干扰强度下分别下降了8.9%和15.3%。2）践踏干扰显著改变了土壤温度，但对土壤含水量没有影响。与对照相比，在10%和30%的干扰强度下，生物结皮的土壤温度分别降低了0.4℃和1.2℃，但在50%和70%的干扰强度下分别升高了1.1℃和1.0℃。3）在不同干扰强度下，苔藓生物结皮的呼吸速率与土壤温度呈显著指数关系，与土壤含水量呈线性正相关。然而，苔藓生物结皮呼吸速率与苔藓生物结皮特征之间的相关性不显著。土壤温度和含水量分别可以解释苔藓生物结皮呼吸速率总变异的70.6%-96.3%和49.1%-70.0%。总之，放牧和践踏影响了苔藓生物结皮的呼吸速率，短期适度放牧和践踏会产生积极影响。另一方面，过度放牧和践踏会降低苔藓生物结皮的呼吸速率。因此，未来关于黄土高原土壤碳平衡的研究应考虑放牧和践踏对生物结皮呼吸的影响。
