摘要
对吉兰泰地区大面积梭梭林天然更新状况研究结果表明：１．吉兰泰地区的梭梭林盖应小、密度低、分布不均匀。林内幼苗极少，幼树不足，幼苗、幼树、成年村之比为０：２４．６：７５．４，天然更新状况不良，其关键为幼苗极少或无。２．对吉兰泰地区梭梭林天然更新不良的原因进行了探讨，结果表明：种子不足和人为活动对天然更新有一定影响，但大气降水尤其是４、５月份的降水缺乏是导致梭梭林天然更新不良的主要原因。３．梭梭种子成苗与水分的关系为：４、５月份种子出苗约需５ｍｍ左右大气降雨，人工降雨则需９ｍｍ，发芽率随水量增加而提高，并受覆沙厚度影响。４．梭梭种子萌发成苗受多种因素制约，沙埋适应的种子与各因素综合作用的数学模型为：ｙ＝３７．１５１＋１．４５９ｘ＿１一０．３９３ｘ＿２＋１．４５４ｘ＿３一１．７８８ｘ＿４＋０．８４４ｘ＿５＋０．１３９ｘ＿６．其中ｙ为出苗率．ｘ＿１为降水量，ｘ＿２为平均气温，ｘ＿３为平均地温，ｘ＿４为平均最高地温，ｘ＿５为日平均蒸发量，ｘ＿６为干沙层厚度。
On the basis of amount wilde investigation simutating test and experiment, thethesis has studed the situation of natural regeneration of larg scale Halcxylon ammodendornforest in Ji LanTai region. The results is 1.As the Haloxylon ammordendron forest in Ji Lan Tai region;it's density is much lowerand distribution isn' t even. The seedling in the forest is few,and the young tree is unsuffi-cient.The proportion of seedling.young tree and adult is 0: 24.6: 75.4,So the situation ofnatural regeneration is't well.The key reason is absent of seediing. 2.Absent of seed and human action influence natural regene ration of H. ammodendronto a certain extent. And the absent of rainfali,espeicaly in April and May, is the main reasonthat make the natural regeneration of H,ammodendron forest unwell.3.The relation of seedling surive and rainfall is In April and May, it is necessary for see-ing survive that rainfall is 5mm or man-made rainfall is 9mm.The germination rate raiseswith rainfall increase and was influenced by thickness of covered sand. 4.Many fators restricted the seed germination and seedling surrive of Haloxylon ammod -endran。 The mutipel modle of the relation of seedling surrive rate and factors isy= 37.151+1.459x_1一0. 393x_2+l.454x_3一1.788x_4+0.844x_5+0.139x_6 In the modle:y一seedling survive rate x_1一rainfall ,x_2一mean air tepmeratue during the date for living;x_3一mean temperature on ground during the date for living; x_4一Mean Maxim temperature on grourd during the datefor living; x_5一thickness of dry sand during broadcasting
