沙漠化过程中四个共有种的生长和抗氧化系统酶类变化

Changes of four common plant populations growth and their anti-oxidative enzymatic system in desertification process.

探讨了自然条件下沙质草原沙漠化过程中 4个共有植物种群的形态、生长和抗氧化系统酶类变化规律 .结果表明 ,沙漠化过程中共有种种群株高、密度、密度百分比总体上呈降低趋势 ,其中扁蓿豆中度沙漠化阶段前生长渐趋旺盛 ,中度沙漠化阶段后生长受到限制 ,未达到显著水平 (P >0 0 5 ) .羊草受损最重 ,中度沙漠化阶段株高下降至原生植被阶段的 5 7 19% ,密度和密度百分比仅为原生植被阶段的 2 5 0 %和 6 2 2 % .糙隐子草和冷蒿在潜在沙漠化、轻度沙漠化或中度沙漠化阶段株高的增加与种群所处的阶段性优势地位及其抗逆性增强有关 .共有种群SOD、POD活性普遍在潜在沙漠化、中度沙漠化阶段增加 ,轻度沙漠化、重度沙漠化阶段降低 .羊草过氧化氢酶 (CAT)活性较高 ,对沙漠化的响应不显著 (P >0 0 5 ) ;扁蓿豆CAT活性在潜在沙漠化、重度沙漠化阶段明显升高 (P≤ 0 0 1) .在重度沙漠化阶段 ,共有种 3种酶活性普遍下降 ,只有扁蓿豆CAT活性上升 .共有种群丙二醛含量从原生植被到中度沙漠化阶段均呈“先升后降再升”的变化 ,不同阶段之间差异显著 (P≤ 0 0 5 ) .综合分析表明 ,4个共有种中 ,羊草对沙漠化较敏感 。

This paper studied the changes of the growth and anti-oxidative enzymatic system of four common plant populations during the desertification process of sandy grassland.The results showed that in the process of desertification,the individual height and density and the density percentage of the populations all had a decreasing trend.The growth of Melilotoides ruthenica was more vigorous before moderate desertification (MD) stage,but restricted after that.In MD stage,the growth of Leymus chinensis was heavily restricted,and its individual height,density and density percentage accounted for 57.19%,2.50% and 6.22% of those in original vegetation (OV) stage,respectively.The individual height and density of Cleistogenes squarrosa and Artemisia frigida increased in the stages of potential desertification (PD),light desertification (LD) or MD because of their phase status of dominant species and their stronger stress resistance.The SOD and POD activities of the common plant populations increased in PD and MD stages,but decreased in LD and heavy desertification (HD) stages.The CAT activity of Leymus chinensis was higher,whose response to desertification was not significant (P>0.05),and that of Melilotoides ruthenica increased significantly in PD and HD stages (P≤0.01).The activities of the three anti-oxidative enzymes in the common plant populations,except the CAT activity of Melilotoides ruthenica,decreased in HD stage.The MDA content in the common populations increased firstly,then decreased,and finally increased from OV to MD stage,and had a significant difference in different desertification gradients (P≤0.05).Based on the integrated analysis of the ecological and physiological changes,it could be concluded that Leymus chinensis was more sensitive to desertification,while Melilotoides ruthenica had a stronger bioenergy.