五种高山植物的个体生长在融雪梯度上的变化

在青藏高原东部的一个天然高山雪床,沿着融雪从早到晚的顺序设置3个融雪梯度部位,并对每个梯度部位的环境因子和5种典型植物的个体生长特征进行测量和比较.结果表明:3个梯度部位间的融雪时间、土壤含水量和地表温度日较差有显著不同,而土壤营养成分(总N、总P、总K、可溶性的N、P)及pH无明显变化.根据个体生长在融雪梯度上的变化趋势,5种植物可分为3种类型:第1类包括黑褐穗苔草(Carex atrofusca subsp. minor (Boott) T. Koyama)和西北黄芪(Astragalus fenzelianus Pet.-Stib.),其株高、单株叶数、单叶面积和地上生物量随融雪的推迟而增加;第2类包括斑唇马先蒿(Pedicularis longiflora Rudolph var. tubiformis (Klotz.) Tsoong)和川西小黄菊(Pyrethrum tatsienense (Bur. et Franch.) Ling ex Shih.),其个体生长随融雪的推迟而下降;第3类包括长叶火绒草(Leontopodium longifolium Ling),其个体生长特征基本不随融雪时间而改变.

Changes of Five Alpine Species' Individual Growth Along Snowmelt Gradient

In a natural snowbed on the Eastern Tibetan Plateau,three portions were established along a snowmelt gradient.Environmental factors and plants'growth of five herbaceous species in each portion were measured and compared.The results showed that snowmelt timing,soil water content and amplitude of diurnal temperature variance at soil surface in March,April and May differed greatly,whereas no significant differences in soil nutrient contents (total N,total P,total K,soluble N,soluble P) and pH were found.According to individual growth along the snowmelt gradient,five species were divided into three groups.The first group included Carex atrofusca subsp.minor (Boott) T.Koyama and Astragalus fenzelianus Pet.-Stib.whose height,number of leaves per stem,area per leaf and aboveground biomass increased with increase in snow depth.The second included Pediculars longiflora Rudolph var.tubiformis (Klotz.) Tsoong and Pyrethrum tatsienense (Bur.et Franch.) Ling ex Shih.that decreased their height,leaves per stem,area per leaf and aboveground biomass with increase in snow depth.The last included only one species Leontopodium longifolium Ling that did not evidently change its individual growth along the same snow gradient.