塔克拉玛干沙漠腹地两种灌木有效根系密度分布规律的研究

Distribution characteristics of effective roots density of two shrubs in hinterland of Taklimakan Desert

在塔克拉玛干沙漠腹地通过分层分段挖掘法对滴灌条件下多枝柽柳(Tamarix ramosis-sima)和梭梭(Haloxylon ammodendron)幼苗根区有效根长密度和有效根重密度空间分布进行了研究。结果表明:梭梭幼苗平均有效根系密度为多枝柽柳幼苗的3倍左右。在垂直方向上,两种灌木的有效根系密度的变化因树种而异,多枝柽柳幼苗随土层深度的增加呈指数递减,而梭梭幼苗随土层深度的增加呈单峰型曲线。在水平方向上,两种灌木幼苗有效根系密度均随距离植株基径距离的增加呈指数递减。非线性参数拟合分析表明:采用RD=eA+BX+CZ函数模型能较好地反映滴灌条件下多枝柽柳幼苗的有效根系密度的空间分布。

The study area is located in the hinterland of the Taklimakan Desert, where the annual and monthly av- erage temperature in July （the hottest month） and December（ the coldest month）are 12.4℃, 28.2 ℃ and -8.1 ℃, the extremely maximum and minimum temperatures are 45.6 ℃ and - 22.2 ℃, respectively. The annual accumulated temperature （ ≥ 10 ℃ ） is 4 621.8℃ ; the frost-free period is about 283 days, the annual sunshine duration is about 2 571.3 hours; and the annual precipitation and evaporation are 36.6 mm and 3 638.6 mm respectively. The strong winds and dust weathers occur frequently. In this paper, the spatial density distributions of effective root length and weight of Tamarix ramosissima and Haloxylon ammodendron seeding irrigation by means of dig methods from left to right and from up to down, respectively. the mean density of effective roots of H. ammodendron seeding was three times as high were analyzed under drip The results indicated that as that of T. ramosissima. In the vertical direction, the density distribution of effective roots was varied with the different of species. The density distribution of effective roots of T. ramosissima seeding was decreased at an exponent function with the increase of the soil depth, while that of H. ammodendron seeding demonstrated a single peak curve. In the horizontal direction, the density distribution of effective roots of two species all decreased at an exponent function with the increase of the distance from the stem. Regression estimation of non-linear parameters showed that model RD = e^A＋Bx＋CZ could preferably reflect spatial distribution of effective root density of T. ramosissima seeding under drip irrigation. The soil moisture of surface layer about two species was relatively low. With the increase of soil depth, the soil moisture was both remain basically stable at 2 percent. But H. ammodendron soil moisture of every layer was lower than that of T. ramosissima.