【作者】 邓伦秀；

【导师】 张建国；

【作者基本信息】 中国林业科学研究院 ， 森林培育， 2010， 博士

【摘要】 林分密度调控是森林经营过程中需要解决的关键技术问题之一。论文利用江西大岗山28年未经人工干扰（5种初植密度）和27年经人工间伐处理（4种间伐强度）的杉木人工林长期定位测定时间序列数据,在按径阶分布统计各测树因子的基础上,系统研究了杉木人工林密度效应及其与材种结构的有关动态规律,得出如下重要结果:1.林分自然稀疏强度随着林龄、初植密度和立地指数级的增大而增大,初植密度和立地指数级越大,林分发生自然稀疏的林龄越小。林龄28年时,14立地指数级的A₂（2 m×3 m）、B₂（2 m×1.5 m）、C₂（2 m×1 m）、D₂（1 m×1.5 m）、E₂（1 m×1 m）各密度小区,自然稀疏总强度分别为1.0%、5.5%、25.7%、37.0%、63.7%,尤以高密度的E₃（1 m×1 m）小区最大,为85.0%。16立地指数级的A1、A3、B1和B3小区,自然稀疏强度分别达到13.0%、7.0%、16.0%、46.0%。2.立地指数级和林龄相同时,林分平均胸径、单株材积、冠幅随初植密度的增大而减小,林分断面积、总材积、蓄积、高径比、枝下高随初植密度的增大而增大。14立地指数级的A₂、B₂、C₂、E₂小区间林分优势高差异不显著,表明优势高的差异主要决定于立地指数,而非林分密度;林分平均高除B₂与C₂小区间差异不显著外,其它小区间差异达到显著性水平,表明在过稀或过密的林分中,密度对林分平均高有显著影响。杉木生长速度快,需要的养分多,在稀植的条件下,单位面积林木获得的营养面积大,促进了树高的生长,同时稀植林分的平均胸径较大,依其求出的林分平均高就大;在密植的条件下,单位面积林木获得的营养面积小,且被压木较多,林分平均高较低。林龄和初植密度相同时,立地指数级越大,所有测树因子的值越大。3.间伐不能有效促进林分平均高、总材积和总断面积的生长,但间伐能有效促进林分活立木平均胸径、单株材积及单木断面积的生长,且随间伐强度增大而增大。林分活立木断面积除弱度间伐与对照间差异不显著外,其它间伐处理间差异达到显著性水平,且有随间伐强度的增加而降低的趋势;间伐处理的林分,虽然单木断面积比对照增长很多,但因间伐后保留木株数明显比对照少,间伐后短期内单木断面积的增长仍补偿不了因株数减少引起的总断面积的减少,但随着林龄的增长,密度小的林分以单木断面积的迅速增长来增加总断面积,密度大的林分以单位面积株数较多来增加总断面,最终各密度林分断面积将趋向一致。4.林分径阶株数（%）和材积（%）的最大分布率所处的径阶,随着林龄的增大向高径阶方向进级。林龄相同时,低密度比高密度林分进级的径阶更高,进级的速度更快;初植密度相同时,立地指数级越高,进级的径阶越高,速度越快。不同间伐水平的径阶株数与材积最大分布率,随间伐强度的增加依次向高径阶方向进级,间伐强度越大,进级的幅度越大,速度越快;间伐强度相同时,立地指数级越高,进级的径阶越高,速度越快。5.林分材种株数（%）和材积（%）的分布因材种不同而不同,中、大径材株数和材积的百分率,随着林龄的增加而递增,初植密度越小、立地指数级越高,递增的速度越快;林龄28年时,中、大径材株数与材积的百分率,16立地指数级的A密度（1667株·ha-1）小区最大,大径材分别为11.5%、14.2%,中径材分别为56.3%、74.8%。不同间伐水平中、大径材的株数（%）和材积（%）,随着林龄的增加而递增;立地指数级越高,间伐强度越大,递增的速度越快。18立地指数级的A区组,中、大径材株数（%）与材积（%）显著大于16立地指数级的D区组与14立地指数级的B区组,且任何间伐小区都显著大于对照小区;林龄20年时,各间伐水平小区株数（%）分别为58.3%、34.9%、36.0%、22.4%,材积（%）分别为81.5%、60.6%、66.3%、50.0%。6.林分的总出材量随着林龄的增加而增加;林龄相同时,随着初植密度的增加而增大;初植密度相同时,随着立地指数级的增大而增大。但活立木出材量占总出材量的比例,立地指数级相同时,随着林分密度的增加而递减;林分密度相同时,随着立地指数级的增加而递减;枯损木出材量占总出材量的比例,则随着林分密度和立地指数级的增加而递增;林龄28年时,14立地指数级的A₂、B₂、C₂、D₂、E₂各密度小区,林分活立木占总出材量的比例,分别为99.6%、98.3%、91.8%、88.7%、69.4%,林分枯损木占总出材量的比例,分别为0.4%、1.7%、8.2%、11.3%、30.6%。间伐林分的总出材量以对照与弱度间伐小区较大,强度间伐与中度间伐小区较小,但林分活立木出材率随着林龄的增加而增加,林龄相同时,间伐小区大于对照小区,表明间伐不能有效促进林分总出材量的增加,但可有效的促进活立木出材率的提高;林分活立木出材率,18立地指数级的A区组,林龄20年时,强度间伐>弱度间伐>中度间伐>对照,分别为78.1%、76.7%、77.1%、76.3%;14立地指数级的B区组,林龄25年时,强度间伐>中度间伐>弱度间伐>对照,分别为76.4%、75.2%、74.5%、74.0%。7.林分活立木规格材（大、中、小径材）的出材率,随着林分密度的减少和立地指数级的增加而增加;林龄28年时,大径材出材率,16立地指数级的A、B密度小区较高,A₁>A₃>B₃>B₁,分别为16.8%、13.2%、9.0%、5.5%,每公顷出材量分别为69.399m³、57.694m³、31.587m³、27.069m³;中径材出材率A₃>A₁>B₁>B₃,分别为53.5%、47.3%、32.1%、31.9%,每公顷出材量分别为234.014m³、195.555m³、157.177m³、111.941m³;但小径材出材率相反,A₃<A₁<B₃<B₁,分别为12.1%、14.8%、36.1%、38.3%,每公顷出材量分别为52.970m³、61.137m³、126.733m³、187.427m³;林龄28年时,16立地指数级A、B密度林分的大径材出材率与出材量都很小,达不到培育大径材的标准,但A密度林分中径材出材率与出材量占很大比重,适宜培育中径材。8.不同间伐强度林分活立木规格材的出材率,随间伐强度和立地指数级的增大而增大;林龄27年时,大径材出材率,16立地指数级强度与中度间伐的D区组较大,各间伐处理中度间伐>强度间伐>对照>弱度间伐,分别为19.0%、17.1%、2.2%、1.8%,每公顷出材量分别为56.376m³、44.239m³、6.832m³、6.325m³;中径材出材率,对照>强度间伐>中度间伐>弱度间伐,分别为47.3%、42.3%、41.6%、24.2%,每公顷出材量分别为146.928m³、123.783m³、105.196m³、85.408m³;小径材出材率,中度间伐<强度间伐<对照<弱度间伐,分别为17.8%、18.8%、25.9%、48.4%,每公顷出材量分别为52.837m³、47.121m³、80.561m³、171.099m³。更多还原

【Abstract】 The question, stand density controlling, is one of the most key technologies that need to settle immediately in forest management. In this paper, the time series data from 28-year-old Cunninghamia lanceolata test forest in Dagang mountant Jingxi Province without artificial interference （5 initial planting density levels） and 27-year-old plantation with thinning treatment （4 different selection cutting levels） was analyzed. Base on the forest measurement factor according to distribution of diameter class, this paper systematically study the density effect and the dynamic changes rules of timber assortment structure for Cunninghamia lanceolata. The results are listed as following:1. The self thinning intensity increased with stand age and primary planting density increasing. The larger planting density was, the younger forest occurred self thinning was. When stand age are 28 years, in the plots A₂（2m×3m）, B₂（2m×1.5m）, C₂（2m×1m）, D₂ （1m×1.5m）and E₂（1m×1m） with the same 14 site index class, the total self thinning intensity were 1.0%、5.5%、25.7%, 37.0%, 63.7%, respectively,the E3（1m×1m） plot, 85.0%, was the largest. In the plots A₁, A₃, B₁ and B₃ with the same 16 site index class, the self thinning intensity respectively reached 13.0%、7.0%、16.0% and 46.0%。2. In the plots with the same site index class and age, the stand average DBH, individual volume and crown width were decreasing with the initial density increasing; the stand basal area, gross volume, stand volume, ratio of height to diameter and clear bole height were increasing with the growth of forest age dominant height, whereas volume were increasing with the growth of the initial density. The stand dominate height of A₂, B₂, C₂, D₂ and E₂ plots with 14 site index class had no obvious difference, the study shows that the difference of dominant height mainly determined by site index class not stand density; The difference in plots except B₂ and C₂ was significant, which suggested that density had an effect on stand dominate height in the excessive thin or dense stand. The Cunninghamia lanceolata grow fast and need more nutrient, Under the condition of density being smaller, the unit area stand obtain more nutrient, which promote the growth of tree height, at the same time the average DBH of the sparse stands was larger, then the stand average height from it was larger, too. Contrarily, when the initial density was larger, the unit area stand obtained less nutrient and the stands had more overstock wood, the stand average height was lower. When the plots with the same initial density and site index class, the larger site index was, the larger values of all forest measured factors were.3.The thinning can’t effectively promote the growth of stand average height, gross volume and the growth of the total basal area, but can promote the growth of stand living trees average DBH, individual volume and the growth of single basal area, and these indices increase with the increasing of the thinning intensity. The total basal area of stand living trees weren’t significant except light thinning and control difference, the difference of other thinning treatments were up to significance level, and there was the trend that decreasing with the increasing of the thinning intensity. In plots with thinning treatment, the single basal area of stand was more than control, but the reserved trees were less than control after thinning, the growth of single basal area can’t compensate the decreasing the total basal area because of decreasing the number of trees in a short time;the small density stand increased the total basal area at the growth speed of single basal area with the increasing of forest age, big density stand increased the total basal area by the larger number of trees per hectare, finally the basal area of each stand density were approached to uniform.4.The diameter class, in which the most trees and volume of stand diameter class located move to the higher diameter class with the stand age increasing. When at the same forest age, the low-density stands own higher extent and faster speed than high-density stands. With the same initial density, the higher site index class and approaching to diameter class were, the faster speed was. The stand diameter class of different thinning level and the most distribution rate of volume approached to high diameter class with increasing thinning intensity. With the same thinning intensity, the higher site index class results in the larger extent and the faster speed.5.The distribution of tree number of wood sorts （%） and volume （%） in stands depended on wood sorts, the percentage of tree number and volume of moderate and big diameter woods increased with stand age. growth increasing speed increased with declination in initial planting density and raise in site index; the proportion of moderate and big diameter woods at the age of 28 in density A plots with 16 site index class was the highest, the big diameter woods was 11.5% and 14.2%, respectively, moderate diameter woods was 56% and 74.8%. At different thinning intensity, the tree number（%）and volume（%）of big diameter woods increased with stand age; the growth rate increased with site index and thinning intensity. The tree number（%）and volume（%）of big diameter woods in density A district with 18 site index class was significantly higher than those in density D plots with 16 site index class and density B plots with 14 site index class, and all thinning plots were remarkably higher than control district; At the age of 20, the tree number （%） in all thinning plots were 58.3%、34.9%、36.0% and 22.4%, the volume （%） were 81.5%、60.6%、66.3% and 50.0%, respectively.6. The gross wood yield of stands increased with stand age, and increase with initial planting density increasing at the same stand age, and increased with the site index increasing when the initial density was same. However, the contribution percentage of wood yield of living trees to gross wood yield decreased with stand density when site index were same. The contribution percentage of wood yield of dead standing trees to gross wood yield increased with stand density and site index; in the plots A₂, B₂, C₂, D₂, E₂ with the same 14 site index class, the percentage of wood yield of living trees in gross wood yield were 99.6%, 98.3%, 91.8%, 88.7% and 69.4%, while proportion of dead standing trees were 0.4%, 1.7%, 8.2%, 11.3% and 30.6%, respectively at the stand age of 28. In the terms of gross wood yield of stands of thinning, there was an apparent difference between control and districts of thinning, but no such difference between control and intensive, moderate districts of thinning, outturn rate of living trees increased with stand age, outturn rate of living trees in districts of thinning was higher than control at the same age, and indicated that the increase in gross wood yield of stands could not be improved by thinning, but promoting outturn rate of living trees. At the stand of 20, the outturn rate of living trees in district A of 18 site index class, intensive thinning> slight thinning > moderate thinning>control, were 78.1%, 76.7%, 77.1% and 76.3%, respectively ; At the stand of 25, the outturn rate of living trees in district B of 14site index class, intensive thinning> moderate thinning> slight thinning>control, were 76.4%, 75.2%, 74.5% and 74.0%, respectively7.The outturn rate of dimension lumber of living trees （big, moderate and small diameter woods） decreased with stand density and increased with site index; At the stand age of 28, the outturn rates of big diameter woods in plot A and B with 16 site index class were higher, A₁>A₃>B₃>B₁,were 16.8%,13.2%,9.0% and 5.5%,respectively, the wood yield per hectare were 69.399m³, 57.694m³, 31.587m³ and 27.069m³; the outturn rates of moderate diameter woods was A₁>A₃>B₃>B₁,were 53.5%, 47.3%, 32.1% and 31.9%,respectively, the wood yield per hectare were 234.014m³, 195.555m³, 157.177m³ and 111.941m³, respectively; In contrary to big and moderate diameter woods, the outturn rates of small diameter woods was A₃<A₁<B₃<B₁,were 12.1%, 14.8%, 36.1% and 38.3%,respectively, the wood yield per hectare were 52.970m³, 61.137m³, 126.733m³ and 187.427m³, respectively; at the stand age of 28, the outturn rate and wood yield of big diameter woods in density A and B with 16 site index class were low, could not meet the standards of big diameter woods, but the outturn rate and wood yield of moderate diameter woods in stands with density A accounted for a dominant proportion, and appropriating to cultivate moderate diameter woods.8.Under different thinning intensity, the total wood yield rate of dimension lumber of living trees increased with thinning intensity and site index; at the stand age of 27, outturn rates of big diameter woods,in 16 site index class and the plot D with moderate thinning treatment were larger,moderate thinning>intensive thinning >control> slight thinning, were 19.0%, 17.1%, 2.2% and 1.8%,respectively, wood yield of big diameter woods per hectare were 56.376m³, 44.239m³, 6.832m³ and 6.325m³; outturn rates of moderate diameter woods was control> intensive thinning>moderate thinning> slight thinning, were 47.3%, 42.3%, 41.6% and 24.2%,respectively, wood yield of big diameter woods per hectare were 146.928m³, 123.783m³, 105.196m³ and 85.408m³; outturn rates of small diameter woods was slight thinning>control>intensive thinning>moderate thinning, were 17.8%, 18.8%, 25.9% and 48.4%,respectively, wood yield of big diameter woods per hectare were 52.837m³, 47.121m³, 80.561m³ and 171.099m³.更多还原