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川西亚高山森林存在明显的季节性冻土现象,该地区的土壤经历着初冬冻融、深冬冻结、早春冻融等过程,同时,该区域冬季受气候变化的影响强烈。为了全面地认识亚高山森林的生态过程,该研究以川西亚高山针叶林两种主要树种——岷江冷杉(Abies fargesii var.faxoniana)和云杉(Picea asperata)为材料,研究其叶片及细根内丙二醛含量、渗透调节物质的含量、组织含水量、过氧化物酶活性以及硝酸还原酶活性在季节性冻土期的变化,同时还比较了冻土期和冻融期细根的比根长,比表面积,直径以及组织密度的变化。研究结果显示:在季节性冻土期,土壤温度昼夜波动幅度小于空气温度波动幅度,细根却表现出更强的过氧化物酶活性以及更高的渗透调节物质含量,说明细根较叶片对季节性冻土更为敏感。与冻结期相比,冻融期土壤温度、空气温度以及空气相对湿度昼夜波动幅度增加,促使云杉叶片可溶性糖含量以及两针叶树种叶片内过氧化物酶活性、脯氨酸含量显著增加,而细根的组织含水量显著降低,脯氨酸、可溶性蛋白质及可溶性糖含量均显著增加,表明冻融期对两针叶树种的影响较冻结期更为强烈。岷江冷杉和云杉的过氧化物酶活性及渗透调节物质含量具有相同的变化趋势,但叶片和细根的膜脂过氧化程度及酶活性变化并不一致,就岷江冷杉而言,细根的丙二醛含量显著增加,而叶片、细根的硝酸还原酶活性均显著降低,云杉仅叶片的丙二醛含量发生变化,且显著降低,说明云杉更能忍耐冻融循环造成的胁迫。研究还发现细根形态在季节性冻土期无显著变化。
Subalpine forests in western Sichuan have obvious seasonal frozen soil phenomenon. The soils in this area experience the process of freeze-thaw in early winter, freezing in winter and freeze-thaw in early spring. Meanwhile, the winter is strongly influenced by climate change. In order to comprehensively understand the ecological process of subalpine forests, two species of sub-alpine coniferous forests, Abies fargesii var. Faxoniana and Picea asperata, were used as materials to study their leaf and fine The content of MDA, the content of osmotic adjustment substance, the content of tissue water, the activity of peroxidase and the activity of nitrate reductase in the soil during the seasonal frozen soil period were also compared. Specific root length, specific surface area, diameter and tissue density. The results showed that the diurnal variation of soil temperature was less than that of air temperature during seasonal freezing and thawing periods, but the fine roots showed more peroxidase activity and higher osmotic adjustment substance content, Seasonal frozen soil is more sensitive. Compared with the freezing period, the fluctuating amplitude of soil temperature, air temperature and air relative humidity in day and night increased during freezing and thawing periods, which promoted the soluble sugar content of leaves and peroxidase activity and proline content in leaves of two conifers increased significantly The water content of fine roots decreased significantly, and the content of proline, soluble protein and soluble sugar increased significantly, which indicated that the effect of freeze-thaw period on coniferous species was more intense than that of freezing period. The activities of peroxidase and the content of osmotic adjustment substance of Abies faxoniana and spruce had the same trend, but the changes of membrane lipid peroxidation and enzyme activity of leaves and fine roots were not the same. For Abies faxoniana, The content of dialdehyde increased significantly while the activity of nitrate reductase in leaves and fine roots decreased significantly. The content of malondialdehyde in leaves of spruce only changed significantly, which indicated that the spruce could more tolerate the stress caused by freeze-thaw cycles. The study also found no significant changes in fine root morphology in the frozen season.