毛乌素沙地天然臭柏群落新梢生长规律的研究

STUDY ON THE FRESH BRANCHES GROWTH LAW OF SABINA VULGARIS NATURAL POPULATION IN MAOWUSU SANDS

本文通过野外定株测定，分析了天然臭柏群落的生长过程、生长规律、物候特点，并讨论了降水、土壤含水率对生长的影响。研究表明，臭柏新梢在４月中旬开始萌动，５～７月进入生长盛期，之后新梢生长速度下降，直到１０月生长停止，生长期内仅形成一个生长高峰。臭柏群落的扩大以匍匐枝延长为主，匍匐枝的生长速度约为直立枝的３～４倍。不同坡向中以东坡生长量最大，南坡生长量最小，且各坡向的生长量均较丘间地小。土壤含水量对新梢生长影响显著，在沙丘上０～３０ｃｍ土壤含水率降至０．６８％时，臭柏仍能旺盛生长。降水与新梢生长关系密切，二者的关系可用方程ｙ＝ａｅ－ｂ／ｘ拟合。

By the field fixed sample plot survey(at different habits), The paper analysed the growth law, phenological characteristic of S [WTBX]vulgaris population, and discussed the factors affected the growth of S.vulgaris such as rainfall, soil water content. The fresh branches of S. vulgaris sprout the buds in mid-April, and step into a stage of the rapid growth on from May to July. Then the growth speed is gradually slow down. The branches stop their growth untill the end of October. During the whole growth season, the growth pattern has one peak. The population developing of S. vulgaris mainly depends on the horizontal branches growth. The speed of horizontal branches growth is 3～4 times than that of vertical branches. There is different growth in different slope direction, the growth is the largest in East slope and the smallest in South slope, but the growth in different slope are all smaller than the growth in bottomland. Soil water content significantly affect the branch growth, S.vulgaris can keeps normal growth through the soil water content is only 0.68% in 0～30cm layer at the top of sanddune. Rainfall is closely related with fresh branches growth. The relation between of the fresh branches growth(y,cm) and rainfall(x,mm) can be expressed in equation:y=ae -b/x .