间伐干扰对冀北山地油松人工林群落演替趋势影响

Effects of Thinning on Succession Trend of Pinus tabulaeformis Plantation in North Hebei Mountain Area

采用网格调查法和分层株数法,分析了不同间伐油松人工林群落的演替趋势。结果表明:间伐经营对冀北山地30 a林龄油松(Pinus tabulaeformis)人工林演替趋势影响明显。如果不对高密度(2 800株.hm-2)且长时间未进行干扰的油松林群落进行干扰,短期内其自然演替趋势不明显。间伐保留较大密度(1 064株.hm-2)和适中密度(648株.hm-2)的群落有可能发展成以现有油松大树为主林层,以演替更新层中竞争胜出的油松、蒙古栎(Quercus mongolica)等为亚林层的复层异龄林。间伐保留较小密度(388株.hm-2)的群落有可能发展成以油松和部分迅速成长的阔叶树为主林层,以演替更新层中逐渐长大的幼树为亚林层的异龄复层混交林,主林层和亚林层中都是以油松为优势种,其他阔叶树为伴生种。间伐保留适中密度(656株.hm-2)且阔叶树种种源较丰富的群落有可能发展成以现有油松大树和演替更新层中竞争胜出的蒙古栎、山杨(Populus davidiana)、黑桦(Betuladavurica)等为主林层,以阔叶树为亚林层的复层异龄混交林,亚林层中以耐阴的蒙古栎为优势种,其他阔叶树为伴生种。适度的间伐强度及增加阔叶树种种源可以加速油松单层同龄纯林向复层异龄混交林演替。

Succession trend of different thinning intensity of Pinus tabulae/brmis plantation community was analyzed by sample grid survey and the layered counting method in north Hebei mountain area. Results showed that thinning has significant effects on succession of P. tabulaeformis plantation with 30 years old. There is no significant succession trend in short term in P. tabulaeformis plantation without disturbance （2 800 trees · hm-2 ）. Community with higher thinning intensity （ 1 064 trees · hm-2 ） and medium thinning intensity （648 trees · hm-2 ） would grow into uneven aged forest with P. tabulaeformis as the main story and other small amount of species, such as P. tabulaeformis and Quercus mongolica, as second story. Community with lower thinning intensity （388 trees · hm-2） would grow into uneven aged forest with P. tabulaeformis and other deciduous trees as the main story. P. tabulaeformis is the dominant species and other deciduous trees are companion species of the main and second stories. Community with the medium thinning intensity （656 trees · hm-2 ） would probably grow into complicated uneven aged forest with P. tabulaeformis and other competitive species, such as Q. mongolica, Populus davidiana, Betula davurica, as the main story and the deciduous trees as second story. Q. mongolica is the dominant species and other deciduous trees are companion species of the main and second stories. The medium thinning and increased deciduous species could promote the simple even aged forest to complicated uneven aged forest.