增温对青藏高原草地生态系统土壤球囊霉素含量的影响

土壤是陆地生态系统中最大的碳库,而球囊霉素作为土壤碳库的重要组分,其变化及其影响倍受关注。该文以对温度变化较为敏感的青藏高原为对象,研究了增温对土壤球囊霉素含量的影响,旨在探讨丛枝菌根在全球变暖过程中的功能。选择青藏高原4个海拔梯度,设置开顶式(OTC)模拟增温和对照2个处理。通过比较模拟增温和对照处理中,球囊霉素含量变化、丛枝菌根与植物根系侵染状况、真菌孢子密度、土壤全碳含量以及球囊霉素与土壤全碳之间的关系,探讨了球囊霉素对增温的响应。结果表明,在青藏高原4个海拔梯度,增温既没有降低土壤总提取球囊霉素的含量,也没有降低易提取球囊霉素的含量。从4个海拔梯度的平均来看,OTC增温处理和对照处理的总提取球囊霉素含量分别为4.35 mg·g-1和4.28 mg·g-1;易提取球囊霉素含量则分别为1.53 mg·g-1和1.63 mg·g-1。同时,增温也没有显著降低总提取和易提取球囊霉素对土壤全碳的贡献。球囊霉素之所以没有受到增温的影响,可能是丛枝菌根真菌对增温不敏感的特性所导致的,因为对比增温与对照处理,可发现植物根系菌根侵染状况未受到影响,其菌根侵染率分别为88.38%和85.28%。丛枝菌根真菌繁殖体孢子密度也与菌根侵染率呈现出相同的趋势,且增温也没有对其产生显著的影响。可见,全球变暖过程中,丛枝菌根真菌通过分泌球囊霉素而起到稳定土壤碳库的作用。

Effect of Warming on Soil Glomalin in Grassland of the Qinghai-Tibet Plateau

Soil is the largest carbon pool in terrestrial ecosystems,and glomalin is an important component of the soil carbon pool.Therefore,the changes and effects of glomalin have received more attentions.Therefore,the impact of global warming on soil carbon pools and soil glomalin have attracted much attentions.In this study,the Qinghai-Tibet Plateau,as one of the most sensitive areas to temperature changes,is used as an object to study the effect of warming on soil glomalin.We selected four elevations gradients,and simulated warming using open top chamber(OTC).The response of glomalin concentration to simulated warming was explored by comparing the differences of glomalin concentration,mycorrhizal colonization,fungal spore density,soil carbon between glomalin and C in soil based on CK and OTC treatments,repectively.We found that,at four elevations gradients on the Qinghai-Tibet Plateau,warming did not reduce the content of total glomalin and the easily extractable glomalin.From the average of the four elevations gradients,the total glomalin content of the OTC warming treatment and the control were 4.35 mg·g^-1 and 4.28 mg·g^-1,respectively;the easily extractable glomalin content of the OTC warming treatment and the control were 1.53 mg·g^-1 and 1.63 mg·g^-1,respectively.Warming did not reduce the contribution of total and easily extractable glomalin to soil carbon content.The reason why glomalin is not affected by warming may be caused by the insensitivity of arbuscular mycorrhizal fungi to warming,because comparing the warming and control treatments,we found the mycorrhizal colonization of the plant roots was not affected.The mycorrhizal colonization rates were 88.38%and 85.28%in the treatments of contral and OTC,respectively.Warming had no effect on the spore density of the arbuscular mycorrhizal fungi propagules.We conclude that arbuscular mycorrhizal fungi play a role in stabilizing soil carbon pools through secretion of glomalin during global warming.