【作者】 谭骏珊；

【导师】 田大伦；

【作者基本信息】 中南林业科技大学 ， 生态学， 2010， 博士

【摘要】 杉木是我国南方亚热带地区特有的优良速生乡土用材树种,已有近千年的栽培历史,杉木林是我国南方集体林区主要经营的森林类型之一。目前,我国南方人工林生态系统的脆弱性、不稳定性和失衡性、地力衰退,生产力下降等问题十分突出。长期定位监测杉木林的生物产量,对于维持杉木林持续的林地生产力,实现杉木林的可持续经营具有重要的理论和实践意义。本文利用湖南会同杉木林生态系统国家野外科学观测研究站20年长期定位观测数据,对两个世代杉木人工林速生阶段(7-11年生)和杆材阶段(14～18年生)和近成熟阶段(20a生)的生物量和生产力进行了比较研究,探讨杉木林生物量和生产力的连栽代马尔效应。主要研究结果如下：1.杉木不同器官生物量分配结构特征。两代不同林龄杉木各器官生物量分配都有明显差异,立地条件对不同林龄第一代杉木各器官生物量分配影响较大,对第二代杉木影响不大。随着林龄的增大,第一代杉木树干在7a-18a间其生物量比例呈上升趋势,从20 a生开始下降。树叶的在7a-20a阶段呈下降趋势。树根的在7a～18a阶段总体上呈下降趋势,20 a时开始上升。树枝的在7a-20a阶段呈下降趋势,但下降幅度不大,除7a生杉木外,其它林龄段生物量所占比例在7%左右。树皮的生物量比例在速生期维持在8%左右,在干材阶段维持为12%。第二代杉木树干生物量在7a-20a生长比率呈上升趋势,但上升速率逐渐降低；树叶在7a-20a阶段呈下降趋势,但下降速率逐渐降低；杉木树根生物量在7a-14a间递增,在14a-20a间生物量递减；树皮在7a～18a上升幅度逐渐减少,到20a时开始下降。树枝在7a-20a阶段的变化没有规律性。两代杉木单株生物量在近成熟阶段差异缩小2.杉木人工林地被物与凋落物生物量。1-5a杉木林内,草本植物生物量为0.75～6.929 t hm-2；灌木层总生物量为1.048～7.773 t hm-2,各组分生物量的分配规律为根>茎>叶。凋落物量(1987年12月造林)13年间(1995-2007),年平均为1109.86(±117.27)kg·hm-2。凋落物中针叶、小枝、落果和碎屑所占比例不同,针叶占54.39%～75.06%,小枝占17.55%～31.52%,落果占的3.15%-13.5%,平均碎屑占2.19%。凋落物量具有明显的凋落节律,并表现为不规则型,凋落峰值有3个,分别出现在2月(90.42 kg·hm-2)、6月(111.42 kg·hm-2)、8月(108.84 kg·hm-2)。凋落物随林龄呈显著的二次曲线关系：y=-10.06x2+361.1x-1747,R2=0.920,P<0.001。凋落物中小枝、针叶、落果与林龄呈显著相关,而碎屑与林龄相关性不显著。3.杉木人工林生态系统生物量比较。随着林龄的增大,连栽杉木林间林分生物量差异逐渐减小。7a生第二代杉木人工林生物量37.90 t hm-2,较第一代(45.38 t hm-2)下降16.48%；11a生为第二代为90.31 t hm-2,较第一代(108.73 t hm-2)下降16.94%；14a生第二代为97.18thm-2,较第一代(104.45 thm-2)下降6.96%；18a生和20a生时,两代连栽杉木人工林系统生物量差异不大,18a生二者在系统生物量总量上的差异仅为1.74 t hm-2,差异值不足其生物量的1.20%,20 a生二者生物量之差占系统生物量的不足5%左右。从杉木不同生长级(Ⅰ级到V级)看出,第一代林分各生长级的生物量均大于第二代林分。4.杉木人工林生态系统生物生产力比较。与第一代杉木人工林年均生产力相比,7a生第二代林年均生产力下降16.38%,11a生年均生产力下降17.29%,14a生年均生产力下降6.96%,18a生年均生产力上升12.95%,20a生年均生产力降幅为8.93%。不同林龄下林分生产力均是以树干生产力为最大,是林分生产力的主要贡献者。5.杉木人工林不同立地类型对生物生产力的影响。7a生杉木林的生物量大小排序为山麓>山坡下部>山坡中部>山洼中部>山洼中上部；11a生为山谷型(33.6 kg/株)>山麓型(30.3 kg/株)>山坡型(16.4 kg/株)。11a生杉木林的生产力大小排序为山谷型(9.89 thm-2 a-1)>山麓型2 (8.35 thm-2 a-1)>山麓型1 (8.33 thm-2 a1)>山坡型(6.43 thm-2 a-1)。山谷型和山麓型林分生产力分别是山坡型的1.54倍1.30倍。6.不同密度和经营措施对杉木人工林生物生产力的影响。林分密度从1501-2000株hm-2到2001～2500株hm-2,从2501～3000株hm-2到3001～3500株hm-2生物量随林分密度增大而增加。当密度从2001～2500株hm-2到2501-3000株hm-2时,林分生物量有所下降。同一立地类型4个不同密度的11a生杉木林单株生物量是不同的,其中以3690株hm-2密度的林分单株生物量最高。11a生林分在密度为2750株hm-2、3120株hm-2、3550株hm-2时,树干生物量所占比例依次为61.08%、59.05%、55.10%,是依次下降的。其余14a生、16a生时树干生物量所占比例也是随着密度增大而依次下降的,甚至下降幅度有所增加。在林分密度相近的条件下,山谷型林分生物量大于山麓型的,山坡型的林分生物量最小在50%和30%两种间伐强度处理下树干生物量所占比例较为接近,分别为55.37%、54.82%、55.38%；在16a生时,在3种间伐强度处理下树干生物量所占比例分别为62.21%、64.24%、65.03%。11a生时50%和30%间伐强度下单株生物量分别是对照处理的130.11%和89.25%；而16a生时间伐处理分别是对照处理的167.48%和120.28%。山麓立地条件下,11a生时40%、30%和20%间伐强度下单株生物量分别是对照处理下生物量的122.27%、125.39%和119.53%；而16a生时间伐处理较对照处理下生物量分别是145.39%、153.40%和142.23%。在山麓型立地条件下,11a生时相对生物量排序为125.4(30%间伐)>122.3%(40%间伐)>119.5%(20%间伐)>100.0%(对照),而16a生的排序为153.4%(30%间伐)>145.4%(40%间伐)>142.2%(20%间伐)>100.0%(对照)。不同间伐强度杉木林生态系统生物量的影响。在三种立地条件下,林分的生物量均是以树干生物量最大。在山坡型立地条件下,11a生杉木林树干生物量占林分生物量的比例在54.99%～55.22%之间,树根生物量占林分生物量比例在22.51%-23.43%之间。表明间伐强度对树干生物量与树根生物所占林分总生物量比例几乎没有影响。但在山谷型立地条件下,11a生时树干生物量与树根生物量占林分生物量的比例分别是59.23%～59.31%与23.82%～23.97%内；在山麓型条件下,二者的比例变化在60.08%～64.54%和19.89%～21.59%范围内变化。在林分速生阶段(11a生时),较高强度的间伐(40%和50%)导致林分乔木层生物量有一定的减少,减少的程度因立地条件不同而异。16a生时,山坡型立地50%与30%间伐后二者林分生物量较为接近,山谷型立地40%与20%间伐二者林分生物量较接近,且均较对照低。在山麓型立地条件下16a生林分采取不同间伐强度措施后林分生物量变化情况较为多样化。在40%间伐强度下,林分生物量较对照区林分生物量稍低；在30%间伐强度下,林分生物量为对照区的112.3%；在20%间伐强度下,林分生物量为对照区的116.8%；30%和20%间伐处理下林分生物量是相当的,说明这两种处理对林分生物量的影响效果是近似的。更多还原

【Abstract】 Chinese fir (Cunninghamia lanceolata (lamb.) hook) has been cultured for more than 1000 years in China, which is the special and native and fast growing tree of southern subtropical region. In the past three decades, more than nine million hectares of Chinese fir plantations have been established in Southern China. However, major concerns have been raised about the sustainability of the plantations in terms of site productivity and soil nutrients. Since 1970s, a long term research project has been conducting to monitor the changes in structure, function and productivity of Chinese fir plantations at the Huitong Ecosystem Research Station, Central South University of Forestry and Technology, Hunan Province, China. Long term research of biomass was a key role in maintaining stand productivity and sustainable management of Chinese fir plantations.Here about 20 years of continuous data from the Huitiong research station was employed to compare standing biomass and net primary productivity (NPP) of the two successive rotations on the same sites, and to discuss the malter effect in biomass and productivity. The standing biomass and NPP were measured and compared from four different-aged stands (7,11,14 and 18 year-old) in two successive rotations on the same sites. The main results were as the follows:a) The characteristics of biomass distribution in organs. There was significant difference between the two rotations in biomass distribution in organs varing with stand age and rotations. Distribution of biomass in organs of the first rotation was main influence by site conditions, whileas it was not the same to the second rotation. The percentage of biomass in stem to the whole individual tree of the first rotation (abbreviation as R1) was on the increase with age from 7a to 18a, and on the decrease from 20 years old. Whileas the percentage of biomass in leaves to the whole individual tree was slowly decreased with age from 7a to 20a, maintaining the percentage of about 7 percent except the age of 7 year old. The percentage of biomass in bark to the whole individual tree kept at 8 percent during the fast growing stage and 12 percent during stem growing stage. In the second rotation (abbreviation as R2), the percentage of stem biomass to the total tree was on the increase during the period of 7a to 20a, with a slow decreasing with age. The percentage of leaf biomass to the total tree downtrended from 7a to 20a with a decreasing desendance. Biomass in root increased with age of 7a to 14a, and decreased with age of 14a to 20a. The extent in increase of tree bark biomass downtrended from 7a to 18 a, and began to decrease from 20a. Change in biomass of branches showed irregularity during the period from 7a to 20a. The difference in biomass between the two rotations reduced from the near to maturity stage.b) Biomass in the herbs was about amount of 0.75 to 6.929t hm-2, biomass in shrubs of 1.048 to 7.773 t hm-2 during the period of 1a to 5a, with regular distribution ranking as root > stem> leaves. The amount of litterfall was annual average of 1109.86 (±117.27) kg·hm-2 during the period from 1995 to 2007. The percentage of biomass in litterfall varied with organs, for the needle leaves of 54.39%～75.06%, for branchlets of 17.55%～31.52%, for fruit drops of 3.15%～13.5%, for scraps of 2.19%. Seasonal change in litterfall was observed irregularly with three peaks, the first occurred in February of 90.42 kg·hm-2, the second in June of 111.42 kg·hm-2, and the third in August of 108.84 kg·hm-2. Litterfall production (y) was significantly correlated with stand age (x), which can be quantitatively expressed by the regression equation:y=-10.06x2+361.1x-1747, R2=0.920, p< 0.001. There was also a conic relationship (p< 0.05) between the production of branches, leaves and fruits litterfall and forest age, while the relationships of scraps and forest age were not significant.c) The difference in stand biomass between the two rotations decreased with stand age. The stand biomass in the second rotation were reduced by 16.48%,16.94%,6.46%,1.19%, and 1.20% in 7,11,14,18 and 20 year-old stands, respectively when compared to the first rotation. The stand biomass was measured for R1 of 45.38 t·hm-2,108.73 t·hm-2,104.45 t·hm-2,146.70 t·hm-2 and 209.50 t·hm-2, for R2 of 37.90 t·hm-2,90.31 t·hm-2,97.18 t·hm-2, 144.96 t·hm-2, and 199.95 t·hm-2 in 7,11,14,18 and 20 year-old stands, respectively. There was only small difference in stand biomass between 18 year-old and 20 year-old stand, with amount of 1.74 t hm-2 and 9.55 t hm-2 for 18a and 20a, respectively. The percentage of difference to total stand biomass was 1.20% and less than 5.0% for 18a and 20a, respectively. The biomass in the second rotation varied with growth grade from grade I to gradeⅤ, and was less than biomass in the first rotation according to the same growth grade.d) The stand productivity in the second rotation were reduced by 16.38%,17.29%, 6.96%, and 8.93% in 7,11,14, and 20 year-old stands, respectively when compared to the first rotation, with an exception of increase by 12.95% in 18 year-old stand. In all the stand age-classes, the stand productivity was main contributed by stem productivity, which indicats that the stem productivity was a key component of the whole stand productivity.e) The biomass was ranked as mountain foot> side-hill cut> middle hillside> middle bottomland> upper part of hillside for 7 year-old plantations, whileas vally type (33.6 kg per tree)> mountain foot (30.3 kg per tree)> hillside (16.4 kg per tree) for 11 year-old plantations. The productivity of 11 year-old plantations was sorted by vally type (9.89 t hm-2a-1)> mountain foot 2(8.35 t hm-2a-1)>mountain foot 1 (8.33 t hm-2a-1)> hillside (6.43 t hm-2a-1). The stand productivity at the valley and the pediment were 1.54 and 1.30 times higher than those at the hillside.f) Biological productivity of Chinese fir plantation was affected by different densities and management measures. Biomass increased with stand densities increasing which were from 1501～2000 individual hm-2 to 2001～2500 individual hm-2, and from 2501～3000 individual hm-2 to 3001～3500 individual hm-2. Stand biomass were decreased when the densities were from 2001～2500 individual hm-2 to 2501～3000 individual hm-2. Individual biomass of 11 a stands with 4 different densities was different in the same site type, in which individual tree biomass was the highest in the stand densities 3690 trees hm-2. The proportion of stem biomass were 61.08%,59.05%,55.10%, respectively, when the densities were 2750 individual hm-2,3120 individual hm-2,3550 individual hm-2 in 11a stands. And the proportion of stem biomass of 14a and 16a stands were decreased with decreasing densities. In similar stand densities, stand biomass in valley stand was higher than those in the pediments, stand biomass in slope type stand was lowest.The proportion of stem biomass to individual tree at 50% and 30% thinning treatments were close to the contrast, with values of 55.37%,54.82%,55.38%, respectively. The proportion of stem biomass in 16a stands were 62.21%,64.24%,65.03%, respectively, under 3 thinning treatments. Stem biomass of 11a stands under 50% and 30% thinning treatments were higher 130.11% and 89.25% to the control, and Stem biomass of 11a stands under 50% and 30% thinning treatments were higher 167.48% and 120.28% to the control.In the pediment site condition, individual biomass of 11a stands under 40%,30% and 20% thinning treatments were higher 122.27%、125.39% and 119.53% to the control, and individual biomass of 16a stands under 40%,30% and 20% thinning treatments were higher 145.39%、153.40% and142.23% to the control, respectively.In the pediment site condition, relative biomasses of 11a stands were increased as follows, 125.4 (30% thinning treatment)> 122.3%(40% thinning treatment)> 119.5%(20% thinning treatment)> 100.0%(the control). relative biomasses of 11a stands were increased as follows,153.4%(30% thinning treatment)> 145.4%(40% thinning treatment)>142.2%(20% thinning treatment)>100.0%(the control)The biomass of Chinese fir ecosystem was affected by different thinning treatments. In three site conditions, the stem biomass of all the stands were highest. In the mountain slope conditions, stem biomasses of 11a fir stands accounted for 54.99%-55.22% of the stand biomasses, root biomasses of 11a fir stands accounted for 22.51%-23.43% of the stand biomasses, this suggested that the proportion of stem and root biomasses of stand biomasses were no affected by different thinning treatments. However, in the valley conditions, stem and root biomasses of 11a fir stands accounted for 54.99%-55.22% and 23.82%-23.97% of the stand biomasses, respectively, and in the pediment conditions, stem and root biomasses of 11a fir stands accounted for 60.08%-64.54% and 19.89%-21.59% of the stand biomasses, respectively.In the fast-growth stages (11a stand), higher thinning treatments, such as 40% and 50%, caused to the decreasing of the tree layer biomass of the Chinese fir. In the mountain slope conditions, stand biomass of 16a stand were closed under 50% and 30% thinning treatments. In the valley conditions, stand biomass of 16a stand were closed under 40% and 20% thinning treatments. In the pediment conditions, stand biomass of 16a stands were diversity under different thinning treatments, the stand biomasses was lower than the control under 40% thinning treatments, the stand biomasses was 1.123 times and 1.168 times higher to the control, under 30% and 20% thinning treatments, respectively, which obviously indicated that the stand biomass were affected similarly by the 30% and 20% thinning treatments.更多还原