黄河源区褐鳞苔草的固沙生物学特性

褐鳞苔草(Carex brunnescens)是黄河源区(玛曲)沙漠化草地具有较强固沙能力的先锋植物,对维护玛曲高寒草地生态系统稳定性有重要作用。为了揭示褐鳞苔草固沙的生物学特征,本研究在野外观测了其物候学特征,地上和地下器官生长进程以及地下器官形态学特征。结果表明,褐鳞苔草返青早,生育期较长,具有二次开花和结果的生长特性。褐鳞苔草单株叶宽、单株叶长、单株叶片数量、群落密度、群落盖度和群落叶片密度从展叶期-果实成熟期-黄枯期呈显著增加而后趋于稳定;而单株叶丛高度、单株叶面积和群落叶片面积呈显著增加而后减小的趋势。褐鳞苔草地下茎(水平茎和垂直茎)和根系适宜生存的沙层深度为0-60cm。不同沙层深度(0-20、20-40和40-60cm)均以直径为0.2~0.5mm的中根数量最多,在20-40cm沙层内细根(0.2mm)的根系总长度均最大,0-20cm沙层内中根根系总长度最大。在10-30cm沙层内,水平茎,垂直茎和主根长度、鲜重和干重均最大,40-50cm沙层内最小。以上结果表明,褐鳞苔草能很好地适应高寒风沙生境,可作为玛曲高寒沙漠化草地生态恢复的建群种,具有良好的推广应用前景。

Biological sand-fixation characteristics of Carex brunnescens in Yellow River source region

Carex brunnescens is a pioneer plant that has an excellent ability to fix sand and plays an important role in maintaining the ecosystem stability of the Maqu desertified alpine grassland of the source area of the Yellow River.In this study,the biological characteristics (phenological characters,the above-and belowground growth processes,and the morphological characters of belowground organs) of C.brunnescens was studied in a field observation experiment.The results showed that C.brunnescens has the characteristics of turning green earlier than other plants,a long growth period,and two flowering and fruiting cycles.The leaf width,length,and count of individual plants,and the community plant density and leaf density showed significant increases from the leaf growth stage to the fruit maturity stage,and then tended to be stable in the withering stage,while the plant height,leaf areas of individual plants,and community leaf areas showed significant increases at first and then decreases.Underground stems (horizontal and vertical stems) and roots of C.brunnescens could survive in sand of depths 0-60 cm.There were more mid-sized roots (0.2～0.5 mm) than other root size classes in all soil layers (0-20,20-40,and 40-60 cm).The total length of fine roots with ＜0.2 mm diameter was maximal in the 20-40 cm sand layer and,0.2～0.5 mm diameter roots maximed in the 0-20 cm sand layer.The length and fresh and dry weights of the main root and horizontal and vertical stems was maximal in the 10-30 cm sand layer,and minimal in the 40-50 cm sand layer.These results showed that C.brunnescens has unique biological characteristics which could well adapt to the Maqu alpine sandy habitats,and is a species that has good potential for ecological restoration in Maqu desertified Alpine grassland.