青藏高原高寒草甸退化对矮嵩草有关生理特性的影响

该研究采用空间分布代替时间演替的方法,选取青藏高原青海省果洛藏族自治州玛沁县境内典型的未退化草甸和退化草甸样地,分别设置3个5m×5m的样方,于6至9月下旬上午进行植株和土壤采样,测定矮嵩草生理指标,探讨高寒草甸退化所导致的环境变化对自然生长状态下矮嵩草生理特性的影响机制。结果表明:(1)与未退化草甸相比,退化导致土壤表层速效氮含量极显著降低,而速效磷和速效钾含量显著升高;全氮、全磷和全钾的含量总体上表现为未退化草甸低于退化草甸。(2)与未退化草甸相比,退化草甸矮嵩草叶中超氧化物歧化酶(SOD)活性在生长前期高而后期低(低4%),谷胱甘肽(GSH)含量在两个样地的变化趋势基本一致。(3)退化草甸矮嵩草叶片可溶糖和可溶蛋白含量在生长后期分别比未退化草甸降低17.6%和34.9%,且9月份降低达极显著水平。(4)生长中期以后,退化草甸矮嵩草叶片叶绿素a、b含量比未退化草甸的下降速度快、含量分别低18.84%和20.68%。(5)退化草甸矮嵩草叶片超氧阴离子自由基(O_2~)的产生速率在9月份极显著高于未退化草甸。研究表明,在非生物胁迫下未退化草甸的矮嵩草具有更高的ROS清除能力和渗透调节能力,退化导致的环境变化可能是矮嵩草在生长后期抗氧化能力降低、衰老早的内在原因。

Effects of Tibetan Plateau Meadow Degradation on the Physiological Characteristics of Kobresia humilis

The study used spatial distribution to replace time succession. We chose typical non degraded meadow and degraded meadow plots in Maqin County, Guoluo Tibetan Autonomous Prefecture, Qinghai Province. Three 5 m×5 m quadrats were set up, plant and soil samples were taken in the morning from the end of June to September, and physiological indexes of Kobresia humilis, was measured to explore the effects of environment changes caused by degradation of Tibetan Plateau alpine meadow on physiological characteristics of K. humilis under natural conditions. The results showed that: (1) compared to non degraded meadow, the available nitrogen content significantly reduced in degraded meadow (P<0.01), but the available phosphorus content and available potassium content significantly increased (P<0.05); The overall performance of total nitrogen, total phosphorus and total potassium contents were lower in non degraded meadow than that in degraded meadow. (2) In degraded meadow, SOD activity of K. humilis leaves decreased in late growth stage (reduced by 4%), the trend of GSH content in two plots was basically the same. (3) The contents of soluble sugar and soluble protein in the leaves of K. humilis in degraded meadow were lower than that in non degraded meadow at late growth stage (reduced by 17.6% and 34.9%, respectively), and significantly decreased in September (P<0.01). (4) After middle growth stage, the contents of chlorophyll a and b in the leaves of K. humilis of degraded meadow decreased more quickly than that of non degraded meadow, and the contents were low (18.84% and 20.68%, respectively). (5) The generate velocity of O^-·₂ in the leaves of K. humilis in degraded meadow was higher than that in non degraded meadow in September(P<0.01). These results indicate that K. humilis has higher ROS scavenging ability and osmotic adjustment ability. Environment change caused by degradation maybe the inner reason that resulted in K. humilis antioxidant capacity decrease and aging more earlier in late growth stage.