大岗山丘陵区杉木中幼林低密度控制及深抚效果

近年来,国际上由于工资水平的提高和劳动力的缺乏,从而普遍采用低密度控制,即加大造林株行距,加大疏伐强度、减少疏伐次数,以提高林分质量,提前获得收益。杉木(Cunninghamia lanceolata Hook)是我国重要用材树种,生产中通常采用多次下层间伐方式。本文对杉木中幼林一次性间伐的合理保留密度即主伐密度以及深抚的有效性进行了研究。一、试验地概况试验是在江西大岗山山下林场陂元Ⅰ区杉木人工林中进行的。地理坐标为114°36’E、27°42’N,地处中亚热带东部罗霄山北端武功山余脉,海拔130-220m,属丘陵山地。土壤为页岩上发育起来的黄红壤,土层厚度为80-150cm,腐殖质层(A+AB)厚度约为25cm。土壤容重为1.2(g/cm~3)左右,pH值为4.4-4.8,有机质含量约为2.5％。气候属中亚热带湿润型,具有四季分明,气候温和,日照充足,雨量充沛的特点:年均降雨量1590.9mm,降雨量集中分布在4-6月,占全年降雨量的45％,年均蒸发量1503.8mm,相对湿度80％,1月平均最低温度-5.3℃,无霜期270天左右。主要林下植被为:杜茎

THIN DENSITY CONTROL AND DEEP SOIL TENDING EFFECT ON CHINESE FIR IN FAST-GROWTH PHASE

From 1987 to 1991 a survey on the rational stand density after one-time final thinning and the effect of deep soil tending orperation on the growth of Chinese fir plantation in fast-growth phase was carried out in Dagangshanmountain, Jiangxi province. The result shows that the reasonable stand densityafter thinning should be kept at 1350 trees/ha or so on sites with a site indexof 16m in the hilly area; if a stand has a initial planting density above 2505trees/ha and no thinning afterward, it will be subjected to the risk of price.On sites with high quality class, the yield volume is maily determined by st-and density while the deep soil tending has no significant effect, the increasedDBH growth by thinning is not detectable untill the second year since the DBHgrowth in the first year by thinning is not significent greater than that in theuntouched stands. It is expected that through one-time final heavey thinningthe rotation for Chinese fir can be shortened by 8 years on sites with highquality clas