黄土高原中部主要引进树种生长过程分析

本文对黄土高原中部引进的奥地利黑松、美国黄松、美人松、欧洲赤松、欧洲黑松等16个树种,林分个体树高平均生长量曲线分两种类型,以欧洲黑松为代表的第一种类型,苗期生长较快,随着年龄的增加,树高平均生长量趋于减慢且逐渐稳定,另外一种类型满足正常的"慢—快—缓慢—稳中有降"的生长规律。树高年平均生长量为0.369±0.097m,以美国黄松和欧洲黑松的最高(0.535±0.052m),以铁杉的最低(0.251±0.044m);树高连年生长量平均值为0.387±0.104m,欧洲黑松的最高,华山松的最低,前者是后者的2.63倍;16树种胸径年平均生长量在林木整个生长过程中变化幅度较小,以美国黄松的最高(1.595±0.192cm),青扦的最低(0.363±0.088cm),二者相差近4倍,就乡土树种白皮松、华山松、金钱松、青扦、铁杉、樟子松(0.6048cm)与外来引进树种(0.8488cm)相比,国外引进树种的生长量远远高于国内引进树种。16树种胸径连年生长量平均值为0.7056±0.2570cm,美国黄松的最大(1.249±0.350cm),青扦的最小(0.376±0.241cm),外国引进树种高出乡土树种50.0%以上。

Comparative Study on Growth Process of Main Introduced Tree Species in the Middle Loess Plateau

The introduced 16 species Austrian black pine,ponderosa pine,pinyon,scotch pine,Austrian pine and so on in the middle part of the Loess Plateau,the process of the average individual height growth can be grouped into two categories,the first type represented by Austrian pine,it grows rapidly in the period of seedlings,along with the ages its growth slows down and gradually stabilizes.The other type follows the growth pattern of ＂show-rapid-slow-stably drop down＂.Its average annual growth in height is 0.369±0.097m,Ponderosa pine and Austrian pine are the highest（0.535±0.052m）,and china hemlock is the lowest（0.251±0.044m）.The mean current annual growth in height of the 6 species is 0.387±0.104 m,the black pine is the maximum,the huashan pine is the minimum,the former is 2.63 times of the later.The variation of the average annual growth at breast height of the above-mentioned sixteen species is not appreciable,the highest of the ponderosa pine is 1.595±0.192 cm,the lowest is Wilson spruce with variation of 0.363±0.088cm.The average annual growth at breast height of the native tree species as bunge pine,huashan pine,golden larch,Wilson spruce,china hemlock and mogol scotch pine is 0.6048 cm,compared with the introduced tree species with 0.8488cm,which growth surpass the native tree species.Among the 16 introduced tree species with the mean current annual growth of 0.7056±0.2590 cm,the ponderosa pine is the maximum（1.249±0.350cm）,and Wilson spruce is the minimum（0.376±0.241cm）,the introduced tree species surpass the native tree species more than 50.0%.