不同坡向梭梭幼苗的生长状况和适应特征

Growth and Adaptation of Haloxylon ammodendron Seedlings in Different Habitats in Guerbantunggut Desert

以古尔班通古特沙漠南缘一年生梭梭移栽苗为研究对象,对梭梭幼苗的地上部分生长状况、蒸腾速率日变化趋势以及根系形态进行了调查,探讨不同坡向梭梭幼苗的生长和适应特征。结果表明,平地、阴坡和阳坡表层0～30cm土壤含水量无显著差异,40～100cm土壤含水量阳坡<阴坡<平地。梭梭幼苗同化枝生长速率和含水量均表现为阳坡<阴坡<平地,其生长速率和含水量可能与根层土壤含水量高低有关。不同坡向梭梭幼苗蒸腾速率日变化均呈"单峰型",12:00—16:00阳坡梭梭幼苗蒸腾速率显著高于阴坡与平地。阳坡梭梭幼苗主根不发达,侧根较多但较短;平地和阴坡梭梭幼苗根系主根发达,以单根为主。这反映出根系对相应生境下土壤水分的适应特征。

Using one-year Haloxylon ammodendron transplants growing in the south part of the Gurban- tunggute Desert, we investigated the aboveground growth, diurnal transpiration rate change and root mor- phology of H. ammodendro seedlings, and explored the growth and adaptation characteristics of H. am- modendron seedlings in different habitats （windward slope, leeward slope, and inter-dune lowland）. The results showed that there was no significant difference in soil moisture contents of the 0-30 cm soil layer a- mong different habitats, while the soil moisture contents of 40-100 cm soil layer were significantly differ- ent among the three haitats, 6.65% - 13.60% at the leeward slope, 1.91% -3.56% at the windward slope, and 3.43 % --3.59 % at inter-dune lowland. Water content and growth rate of the assimilating shoots of H. ammodendron seedling at different habitats performed as similar as the soil moisture content, sug- gesting that water content and growth rate of the assimilating shoots could probably be related to soil mois- ture. The diurnal transpiration rate change of H. ammodendron seedlings at different aspects showed a similarly single-peaked type, with significantly higher diurnal water consumption at the windward slope than that at the leeward slope and the inter-dune lowland during 12：00--16：00. The axial root of H. ammoden- dron seedling at the windward slope was poorly developed, with many but short lateral roots. Whike the ax- ial roots at the inter-dune lowland and the leeward slope were highly developed, with one single axial root, which implied that the root system could adapt itself to the soil moisture under corresponding habitat.