北京地区火炬树的萌蘖繁殖扩散

Dispersal of staghorn sumac in Beijing areas

首次通过调查火炬树单株和火炬树林分的萌蘖繁殖扩散状况和小样方方法调查火炬树林下的乔木树种天然更新,了解火炬树对北京主要植被类型:油松人工林、侧柏人工林、刺槐人工林和灌木丛的扩散入侵情况。调查发现:在北京荒山爆破造林示范区,火炬树单株8a来4 5°扇形单方向扩散的最远距离为8.35 m,扩散萌蘖的最多株数达98株。立地条件差,特别是土层薄,裸露的岩石多是影响火炬树扩散能力的主要因素,但没有对火炬树萌蘖株的生长产生重要影响。扩散的群体中地径以小径阶个体占主体,说明火炬树萌蘖能力旺盛。在已有高大乔木的立地,如侧柏人工林和油松人工林,火炬树虽然能扩散进入,但只是伴生下木,很难形成优势群体;乔木林内光照明显影响火炬树的扩散数量和扩散规律;并且发现有10种北京当地乔木树种能在火炬树林下天然下种更新并且正常生长。分析表明火炬树没有对北京当地乔木群落构成威胁。火炬树能扩散进入邻近的灌木丛,并且扩散进入灌木丛的火炬树明显比扩散进乔木林内的火炬树长得高。火炬树的生物学和生态学特性决定了它是良好的荒山造林的先锋树种,不可能成为顶极群落的优势树种。所以火炬树目前对北京山区自然、半自然森林生态系统没有产生入侵危害。

The dispersal of Rhus typhina into the natural and semi-natural vegetation types in areas of Beijing and the impact of Rhus typhina on natural regeneration of native tree species were studied in order to answer some of the debated questions about planting Rhus typhina in areas of Beijing. Studies on the dispersal of both single trees and of stands were carried out by measuring the number and growth of new trees and their distance from the parent tree or stand edge. Small sample plots were used to investigate natural regeneration in the planted forest. Trees and shrubs of Rhus typhina, Pinus tabulaeformis Carr., Platycladus orientalis (L.) Franco, Robinia pseudoacacia L. comprised the dominant vegetation. The study was carried out in Xishan forest farm, Badaling forest farm and in the bare mountains of Fangshan district. The following is a summary of the results: The longest distance of single-tree dispersion in a 45°sector was 8.35m and the largest number of sprouting trees was 98 in an 8-year period in the bare mountains in Beijing. Poor site conditions such as thin and rocky soil were primary factors inhibiting the dispersal of staghorn sumac. The sprouts were composed of smaller-diameter (lesser than 2.0cm) trees. This showed that staghorn sumac had a high capacity for vegetative reproduction. Although staghorn sumac could invade the plantations, it was only a secondary species and could not become dominant in the local arboreal community. The light intensity in the plantations significantly impacted the number of sprouting trees and pattern of dispersal. The study also showed that 10 kinds of native tree species could regenerate under a Rhus typhina canopy: Koelreuteria paniculata Laxm, Platycladus orientalis (L.) Franco, Ulmus pumila L., Ailanthus altissima (Mill.) Swing. et T.B.Chao, Syringa reticulata (Bl.) Hara var. amurrensis (Rupr.) Pringle, Celtis bungeana Bl., Rhamnus parvifolia Bunge, Malus baccata (L.) Borkh., Acer truncatum Bunge and Crataegus pinnatifida Bunge. The growth of these species was good, so apparently, Rhus typhina didn't endanger the native arboreal community. Staghorn sumac was able to invade adjacent shrub vegetation. The average height of trees sprouting in shrub vegetation was higher than those sprouting in tree plantations. Further studies were needed to determine whether Rhus typhina would impact the growth of shrubs on bare mountains and whether Rhus typhina would influence the local plant biodiversity. The above results indicate that Rhus typhina can establish itself in a harsh environment. It is a good pioneer species in the bare hills. It was concluded that the species is not invasive in the natural and semi-natural arboreal ecosystems in mountainous areas of Beijing.