生态因子对不同坡向缺苞箭竹(Fargesia denudata)生长的影响

Effect of ecological factors on Fargesia denudata growth on different slope aspects

缺苞箭竹(Fargesia denudata)是大熊猫主食竹之一,阐明生态因子对其生长特性的影响对大熊猫栖息地生态恢复具有重要的指导意义.以自然分布于甘肃白水江国家级自然保护区海拔1900-3500 m的缺苞箭竹为研究对象,在不同坡向设置了垂直等高线的样带8条(样带长≥2 km),并在样带上共计设置了样地39个(同一样带的海拔差≥200 m).调查因子有缺苞箭竹的基径、高度和单位面积地上生物量,以及坡位、坡度、海拔、郁闭度、土层厚度等生态因子.采用主成分分析法确定生态因子对缺苞箭竹基径、高度和单位面积地上生物量的影响;并用路径分析法确定生态因子对基径、高度和单位面积地上生物量的直接和间接影响,明确影响缺苞箭竹生长的主要生态因子.结果如下:(1)海拔、坡位、坡度、土层厚度和郁闭度对生长在不同坡向的缺苞箭竹基径和高度影响差异显著(P<0.05),但上述生态因子对不同坡向缺苞箭竹的单位面积地上生物量的影响不同.(2)路径分析表明,海拔、坡位、坡度、土层厚度和郁闭度可能不是导致阴坡(SH)缺苞箭竹基径、高度和单位面积地上生物量差异的原因.(3)影响半阴半阳坡(HSU-HSH)缺苞箭竹基径生长的主要因子是坡位和坡度,影响高度生长的主要因子是坡位,而影响单位面积地上生物量的主要因子是郁闭度.(4)影响阳坡(SU)缺苞箭竹基径生长的主要因子是坡位和海拔,影响高度的主要因子是郁闭度,影响单位面积地上生物量的主要因子是坡度.本研究表明影响不同坡向缺苞箭竹生长的主要生态因子不同.上坡位、坡度<20°、郁闭度0.41-0.6的条件下,有利于半阴半阳坡缺苞箭竹生长;海拔2400-2700 m、中上坡位、坡度21-30°、郁闭度0.41-0.6的条件下,有利于阳坡缺苞箭竹的生长.建议在不同坡向大熊猫栖息地主食竹补栽恢复时,考虑缺苞箭竹生长的适宜区域.(图11表6参53)

Fargesia denudata is a staple bamboo species in the diet of giant pandas.Therefore,elucidating the influence of various ecological factors on their growth characteristics would provide an important guide for the ecological restoration of giant panda habitats.This study aimed to investigate the influence of ecological factors on the growth of F.denudata in the Baishuijiang National Nature Reserve,Gansu,China,located at an altitude range of 1900-3500 m.We set up eight transects(≥2 km long)with vertical contours on different slopes and 39 sample plots(elevation interval≥200 m)to investigate the basal diameter,height,and aboveground biomass of F.denudata,as well as ecological factors such as slope position,slope degree,elevation,canopy coverage,and soil thickness.We used principal component and path analyses to identify the effects of these ecological factors on the basal diameter,height,and aboveground biomass of F.denudata.The results showed the following:(1)the basal diameter and height of F.denudata on the shady slope(SH),half-shady and half-sunny slope(HSU-HSH),and sunny slope(SU)slopes differed significantly(P<0.05)for different elevations,slope positions,slope degrees,soil thicknesses,and canopies.However,these ecological factors had different effects on the aboveground biomass of F.denudate on different slopes.(2)The elevation,slope position,slope degree,soil thickness,and canopy were not the main factors affecting the basal diameter,height,and aboveground biomass of F.denudate on the SH slope.(3)The main factors affecting the basal diameter growth of F.denudata on the HSU-HSH slope were slope position and degree,and the main factors affecting height growth and aboveground biomass were slope position and canopy,respectively.(4)The main factors affecting the basal diameter growth of F.denudata on the SU slope were slope position and elevation,and the main factors affecting height growth and aboveground biomass were the canopy and slope degree,respectively.In conclusion,the main ecological factors affecting the growth of F.denudata differed between the slope aspects.The HSU-HSH slopes were suitable for F.denudata growth at the upper slope position,with a slope degree of<20°and canopy coverage of 0.41-0.6.The SU slopes were suitable for F.denudata growth,which were located at an elevation of 2400-2700 m,on the middle to upper slope,with a slope degree of 21-30°and canopy coverage of 0.41-0.6.When replanting and restoring staple bamboo in giant panda habitats on different slopes,areas suitable for F.denudate should also be considered.