冰冻雪压对杉木人工林近成熟林分危害调查

以受冰冻雪灾较为严莺的江西省大岗山林区杉木近成熟林分为研究对象,探讨杉木林分结构和立地条件与杉木受损类型及灾害发生程度的关系,得到几点主要结论:1)冰冻雪压造成大岗山林区杉木受害株数比例达66.84%,受灾相当严重,杉木林分受害类型可分为弯梢、断梢、斜干、断干、倒地及翻蔸等6种,其中断干和断梢为最主要的2种受害类型.2)杉木林分结构对冰冻雪压危害具有明显的调节作用,灾害主要发生于径阶相对较小的林木,林分内径阶越大的林木其受害程度明显越轻;林分密度与受害强度具极显著正相关,密度越高,林分受损株数愈多,且密度主要影响断干、翻蔸这2种不可逆的受损类型,合理的密度调控至关重要.3)杉木林分的立地条件与受害程度紧密相关,高海拔、高坡位、陡坡处的林分更易受到冰冻雪压的危害,较高的立地指数有利于杉木在遭受冰冻雪压灾害时减轻损失.

Harm of Frost and Snow Suppress to Near Mature Stands of Cunninghamia lanceolata Plantations

The damage of the near mature stands of Cunninghamia lanceolata(Chinese Fir)plantations by the frost and snow press disaster was investigated in Dagang Valley forests in Jiangxi Province.The relationships between the harm extent and stands structure,or site index were analyzed.Three main conclusions were drawn.1)Frost and snow press disaster had caused a proportion of up to 66.84% Chinense Fir plants damaged in Dagang Valley forest.The harm was severe,and the harm of Chinese Fir plant could be divided into six stypes:top bended,top broken,trunk inclined,trunk broken,stem conversed and uprooted,among which,trunk broken and top broken were the major harm types.2)The stand structure of Chinese Fir had obvious regulation effect on loss caused by the frost and snow press disaster.The relatively small trees were more vulnerable to the disaster than the bigger ones,and the bigger the diameters of trees were,the more gently the harm extent was.The stand density had significant and positive correlation with harm intensity of stands,and the high density stands had more damaged plants.Stand density mainly affected two irreversible harm types that were trunk broken and uprooded.Reasonable density control was very important for resistance of Chinese Fir to the frost and snow press disaster.3)Site condition of Chinese Fir stands was closely correlated with harm extent,and the stands in high altitude,high slope location and steep slope were more vulnerable to the frost and snow press disaster.The stands with relatively high site index alleviated damages by the frost and snow press disaster.