黄土高原子午岭人工油松林冠层特性研究

Canopy Characteristics of the Man-made Pinus tabulaeformis Forests in the Ziwuling Mountain of the Loess Plateau

用植物冠层半球影像系统分析测定了黄土高原腹地子午岭林区4个不同龄级油松林的冠层特征和林下光立地系数,并应用α多样性指数对不同龄级人工油松林群落的生物多样性进行了初步研究。结果显示,该地区人工油松林叶面积指数(LAI)在林木生长20a以后达到稳定值;平均叶倾角(MLA)在40a内变化不大;冠型参数(E-LADP)的数值在40a内呈U型波动;综合光立地系数(GSF)、直射光立地系数(DSF)、散射光立地系数(ISF)等参数显示,该地区人工油松林在发育过程中,林下光照明显下降,40a林下光照条件各项指标仅约为10a林的1/3。群落内的生物多样性指数有随年份增长而降低的趋势。

The plant canopy hemispherical photographs system was used to investigate canopy characteristics and solar site factors of the manmade Pinus tabulaeformis forests that were located in the Ziwuling Mountain lying in the hinterland of the loess plateau and belonged to different age groups,and the bio-diversities of the manmade Pinus tabulaeformis forests were preliminarily studied by α-diversity index.The results demonstrated that the leaf area indexes of the manmade Pinus tabulaeformis forests become stabilized after the forests had grown for 20 years;the mean leaf angels of the forests hardly varied within the age of 0~40 years;the ellipsoidal leaf angle distribution parameters of the forests varied in a U-shape pattern;such parameters of the forests as the general,direct and indirect site factors revealed that as the forests developed the light below their canopies became remarkably dim,with the various solar site factors of the forests at 40 years old being approximately one third of those at ten years old;the bio-diversity indexes within the Pinus tabulaeformis communities tended to decline with increased ages.