西藏藏杏居群年龄结构及郁闭度研究
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摘要
运用对比方法对西藏边坝县的藏杏居群年龄结构及郁闭度进行分析,以期初步探明藏杏居群的生存状况。结果表明,不同处理的藏杏居群呈现随年龄级增加,植株数量逐渐增加的趋势;不同处理的藏杏居群幼树差异较小,Ⅲ级以下的藏杏数量约占调查总数10.00%左右,其他均为Ⅳ级、Ⅴ级老树,但农田藏杏处理Ⅴ级藏杏数目占调查总数的64.00%,显著高于山地藏杏的48.00%;同时,随着藏杏年龄级的增加,不同处理的藏杏居群郁闭度变异系数均大致呈现逐渐增大的趋势,除了Ⅰ级幼树外,农田藏杏处理其他各年龄级的藏杏郁闭度均显著低于山地藏杏处理,且农田藏杏处理Ⅱ~Ⅴ级的藏杏郁闭度变异系数在0.015~0.042之间,低于山地藏杏0.043~0.103的水平。结果说明,西藏边坝县的藏杏居群呈老化状态,且农田藏杏老化程度比山地藏杏严重,但由于藏杏居群的年龄层级相对连续,种群恢复潜力较大。
The age structure and crown density of the Armeniaca holosericea forest in Tibet Banbar were determined and analyzed to verify its living conditions. Results showed that the number of Armeniaca holosericea in each age class was increased gradually, and the difference of the saplings with different treatments was small. The number of trees below class Ⅲ accounted for about 10% of the total survey and the others were old trees of class Ⅳ and Ⅴ. The number of the farmland Armeniaca holosericea of class Ⅴ accounted for 64%, significantly higher than that of mountain reservoir Armeniaca holosericea. Meanwhile, the coefficient of variation(CV) of the average crown density appeared an increasing trend with the increase of age classes. Except the saplings of class Ⅰ, the crown density of farmland Armeniaca holosericea was significantly lower than that of mountain reservoir one. The coefficient of variation of farmland Armeniaca holosericea from Ⅱ to Ⅴ was between 0.015~0.042, lower than the average CV of reservoir Armeniaca holosericea, 0.043~0.103. Therefore,it is believed that the Tibet Armeniaca holosericea forest is aging and the degree of farmland one is more serious than that of mountain reservoir one. However, due to its continuous age classes, there is a great reproduction potential of the Armeniaca holosericea.
The age structure and crown density of the Armeniaca holosericea forest in Tibet Banbar were determined and analyzed to verify its living conditions. Results showed that the number of Armeniaca holosericea in each age class was increased gradually, and the difference of the saplings with different treatments was small. The number of trees below class Ⅲ accounted for about 10% of the total survey and the others were old trees of class Ⅳ and Ⅴ. The number of the farmland Armeniaca holosericea of class Ⅴ accounted for 64%, significantly higher than that of mountain reservoir Armeniaca holosericea. Meanwhile, the coefficient of variation(CV) of the average crown density appeared an increasing trend with the increase of age classes. Except the saplings of class Ⅰ, the crown density of farmland Armeniaca holosericea was significantly lower than that of mountain reservoir one. The coefficient of variation of farmland Armeniaca holosericea from Ⅱ to Ⅴ was between 0.015~0.042, lower than the average CV of reservoir Armeniaca holosericea, 0.043~0.103. Therefore,it is believed that the Tibet Armeniaca holosericea forest is aging and the degree of farmland one is more serious than that of mountain reservoir one. However, due to its continuous age classes, there is a great reproduction potential of the Armeniaca holosericea.
引文
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[2]孟凡娟,王超,关法春等.野生藏杏花粉超微结构的观察[J].经济林研究,2011,29(1):132-134.
[3]李荣钦,王中奎,郑维列.西藏林芝觉木沟藏杏光合日变化研究[J].山地农业生物学报.2008,27(3):218-223.
[4]Stewart G H.The dynamics of old-growth Pseudotsuga forests in the western Cascade Range,Oregon,USA.Vegetatio.1989,82:79-94.
[5]Leak William B.An expression of diameter distribution for unbalanced uneven-aged stands and forests[J].Forest Science,1964,10:39-50.
[6]冯涛,张艳敏,陈学森.新疆野苹果居群年龄结构及郁闭度研究[J].果树学报,2007,24(5):571-573.
[7]祖元刚,张文辉,阎秀峰.濒危植物裂叶沙参的保护生物学研究[M].北京:科学出版社,1999.
[8]谢宗强,陈伟烈,江明喜等.八面山银杉林种群的初步研究[J].植物学报,1995,37:58-65.
[9]李英武,张炳乾,赵树俭,宁夏六盘山辽东栎天然更新调查分析[J],陕西林业科技,2003(3):13-15.
[10]陈祥伟,胡海波,林学概论[M].北京:中国林业出版社2005.
[11]林培钧,崔乃然.天山野果林资源-伊犁野果林综合研究[M].北京:中国林业出版社,2000.
[12]曾斌,罗淑萍,李疆等.新疆野巴旦杏形态多样性调查初[J].经济林研究,2008,26(3):107-110.
[13]郑冬梅,曾伟生,智长贵等.三峡库区森林郁闭度的遥感定量估测[J].中南林业科技大学学报,2013,33(9):1-4,26.