桂西南石漠化区3种先锋树种对树冠下青冈和金银花幼苗生长的影响

Canopy Effects of Three Pioneer Trees on Seedling Growth of Cyclobalanopsis glauca and Lonicera maackii in Rocky Desertification Region of Southwestern Guangxi

摘要:

为探讨桂西南石漠化区先锋树种对树冠下其他幼苗生长的影响,采取野外小区试验的方法,对茶条木(Delavaya toxocarpa)、银合欢(Leucaena leucocephala)和任豆(Zenia insignis)等先锋树种树冠下的青冈(Cyclobalanopsis glauca)和金银花(Lonicera maackii)幼苗的成活和生长进行了研究。结果表明,3 种先锋树种能明显降低树冠下的光照强度,对土壤的物理性状亦能起到一定或比较明显的改善作用,但对土壤化学性状则没有或者改善作用较小。3 种先锋树种对青冈幼苗的成活和生长具有比较明显的保育作用;任豆和银合欢对金银花幼苗的成活有保育作用,但对其幼苗生长具有抑制作用,而茶条木对金银花幼苗成活和生长均有较明显的抑制作用,且无论是保育作用还是抑制作用,3 种先锋树种对树冠下同种幼苗株高或枝条的影响要大于对基径的影响。因此,该区植被修复可以选择茶条木、银合欢和任豆等先锋树种作为青冈幼苗的保育植物,而金银花则应选择这些树种的树冠外作为定植点,以减少或消除其对幼苗生长的不利影响。

Abstract:

In order to understand the canopy effects of pioneer trees on seedling growth of other speciecs in rocky desertification area of southwestern Guangxi, the survival and growth traits of Cyclobalanopsis glauca and Lonicera maackii under three pioneer tree canopy, such as Delavaya toxocarpa, Leucaena leucocephala and Zenia insignis, were studied by field plot experiment. The results showed that the three pioneer trees could reduce the light intensity and improve soil physical characters, reduced soil bulk density, increased the total porosity and the field capacity, but they could not change soil chemical features. All the three pioneer trees had certain nurse effects on the survival and growth of C. glauca seedlings. Z. insignis and Leucaena leucocephala improved the survival but inhibited the growth of Lonicera maackii seedlings. D. toxocarpa decreased significantly the survival and growth of Lonicera maackii seedlings. Whether they improved or inhibited the seedling growth, the three pioneer trees had more effects on the seedling height and branch growth than those on basal diameter. Therefore, the pioneer trees D. toxocarpa, Leucaena leucocephala and Z. insignis could be selected as the nurse plants for C. glauca seedling in rocky desertification area in southwestern Guangxi, but Lonicera maackii should be planted outside the pioneer tree canopy to avoid shade effect.