中间锦鸡儿(Caragana intermedia)株丛的水分关系

中间锦鸡儿(Caragana intermedia)对风沙侵蚀有较强的适应性,在毛乌素沙地中,呈星散分布。有的中间锦鸡儿株丛与沙篙(Artemisia ordosica)、羊柴(Agriophlla squarroaum)等组成独特的沙地群落。本文着重研究了中间锦鸡儿株丛的水分关系:(1)中间锦鸡儿叶片的蒸腾速率。通常在上午10时和下午2时左右有峰值,中午时蒸腾速率稍有降低。早晨或阴天,光照较弱,气温较低,老茎叶片的蒸腾速率小于幼茎叶片;但在光照强,气温高的条件下,幼茎叶片的蒸腾速率小于老茎叶片。这意味着幼茎叶片比老茎叶片有较强的控制蒸腾失水的能力。(2)一个占地70-80m~2的中间锦鸡儿株丛的日蒸腾失水量达53kg(0.7mm),其中从老茎叶片腾掉的水分约占3/4。这是因为老茎叶量为幼茎叶量的3倍。(3)在毛乌素沙地,中间锦鸡儿通常生长在水势较高的(-0.42MPa)沙土中,却处在水势很低的(-109.20MPa)大气环境中。因此,中间锦鸡儿可从沙土中获得良好的水分供应。

Water Relations of Caragana intermedia Thicket

Caragana intermedia was well adapted to soil erosion. Mamy C. intermedia thickets which scttered in Maohosu developed into a special community with Artemisia ordosica and Agriophylla squarrosum etc. In this paper, water relations of C. intemedia thick- et were studied. 1. Transpiration of the leaves usually had two peaks at 10:00 A. M. and 2:00 P.M.,stight depression during midday. The amount of transpiration from the leaves of old stem was lower than the leaves of new stem in morning or on cloudy day. But at conditions of intensive light and high air temperature, the amount of transpiraion from all the leaves of new stem was lower than the leaves of old stem. This means that the leaves of new stem had more ability to limit water loss. 2. One C. intermedia thicket which occupied 70 to 80m~2 area usually lost 53 kg water per summer day. The amount of water lost from the leaves of old stem was three times of the leaves of new stem 3.In Moahosu Desert Cintermedia grew in higher water potential of sand soil, but water potential of surrounding atmosphere was very low. So, it may be easy to obtain water from the sand soil. C. intermedia thicket could loss about half of annualpreei pitation in growth season.