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1.
以通山县大幕山林场国家储备林为研究对象,按蓄积采伐强度设置对照(0%)、低强度(15.7%)、中强度(27.0%)、高强度(36.0%)、超高强度(45.6%)5个处理建立20块固定样地,对杉檫混交林目标树经营成效进行了监测。结果表明:作业样地2020年与2019年相比,目标树平均胸径生长量增加0.52 cm/年,单位面积蓄积生长量增加4.38 m3/(hm2·年);同时,2020年4种采伐强度作业样地平均每100 m2天然更新树种数6.25个,新增天然更新株数21株,而对照样地每100 m2天然更新树种数仅3个,新增天然更新株数仅12株。由此可见,目标树经营既促进了林木胸径生长,增加了林分蓄积量,同时又改善了林下天然更新,增加了物种多样性,可为国家储备林项目营林措施的选择提供有力支撑。 相似文献
2.
该项试验共分2个部分.(1)造林密度试验,小区面积为600
m2,5个处理,即1 667株.hm-2(A)、3 333株.hm-2(B)、4～983株.hm-2(C)、6 633株.hm-2(D)、9967株.hm-2(E);(2)造林密度调控试验,造林设计方法与造林密度试验相同,但在林分生长过程中,按密度管理图的密管线0.5为标准进行间伐,间伐后保留密度要与临近的下一个初植密度较稀植的林分密度基本相同,两者进行比较.试验结果(1)造林密度试验,优势高、平均高、平均胸径均随年龄的增加而递增,随密度的增加而递减,优势高9a、平均高6
a、平均胸径5 a,密度间差异已达显著性水平;林分蓄积量则随年龄增加而递增,5～7
a,密度间差异显著,8～18a,只有A密度与E、D密度差异显著;枝下高随密度、年龄的增加而递增,12～a后,C、D、E密度间的差异很小;冠幅随密度的增加而递减,随年龄的增加而递增,9～10a后,各密度则随年龄增加而缓慢递减.(2)造林密度调控试验,同一指数级,间伐后的林分与其密度基本相同未间伐的林分比较,其优势高、平均高差异不明显;立木蓄积前者小于后者;总蓄积(立木蓄积+间伐蓄积)前者大于后者;同一指数级,初植密度不同的林分,间伐后与密度基本相同未间伐林分的蓄积百分比,初植密度大的大于初植密度小的;指数级不同,而初植密度相同的林分,间伐后与密度基本相同未间伐的林分总蓄积百分比,高指数级的比值大于低指数级的比值. 相似文献
3.
【目的】以河南登封林场栓皮栎人工林为研究对象,研究抚育间伐对林分不同生长阶段林木株数、林木直径分布和树高分布的影响,为制定科学合理的抚育经营措施奠定理论和技术基础。【方法】在株数强度为31.55%的间伐林分和条件基本一致的未间伐林分内,分别设置1个1 hm2样地,间伐作业2 a后获取每木检尺数据,分别利用Normal分布、Gamma分布、Lognormal分布、Weibull分布、Logistic分布函数对间伐样地和对照样地栓皮栎人工林林木个体直径分布、树高分布进行拟合,并应用Kolmogorov-Smirnov(KS)拟合优度检验,选择拟合效果最好的分布模型。【结果】1)间伐和对照样地幼树、小树和大树林木株数比例分别是9:642:582和229:978:585。相比对照样地,间伐样地林木小树和大树生长阶段株数比重较高。2)间伐样地林木直径分布范围主要集中在8~18 cm,高于对照样地的4~16 cm。KS拟合优度检验结果表明,间伐样地林木直径分布采用Weibull分布拟合效果最好,Normal和Logistic分布次之;对照样地林木直径分布采用Weibull分布拟合效果最好,Normal和Gamma分布次之。3)间伐样地和对照样地林木树高级分别为8~16 m和4~14 m,但KS拟合优度检验结果表明,5种分布函数对间伐样地和对照样地树高分布拟合优度排序一致,说明抚育间伐对林分树高分布的影响不明显。【结论】抚育间伐调整了栓皮栎人工林林分的直径结构,林分直径分布向较大径阶方向偏移,使林分直径分布结构更趋于对称分布,但对树高分布影响不明显。 相似文献
4.
Thinning of Korean pine (Pinus koraiensis Sieb. et Zucc.) is used to facilitate timber and cone production. The present study in Northeast China investigated the effects of thinning intensity on individual tree growth, temporal variation in cone yield, and seed quality in Korean pine plantation. In 2005, five thinning intensity levels (none, extreme, heavy, moderate and light) were set in 15 permanent plots in a 32-year-old Korean pine plantation at Mengjiagang Forest Farm, Jiamusi City, Heilongjiang Province. We recorded tree growth and seed cone production from 2013 to 2016, i.e., from 8 to 11 years after thinning. Except for height growth, thinning increased tree growth (diameter at breast height and crown size) and improved cone yield. The extreme thinning treatment (to 300 trees per hectare) resulted in the largest tree diameter, tree volume, crown size and 4-year cone production per tree. The highest cone yield per tree in the mast year (2014) was observed when stands were thinned to 500 trees per hectare (heavy thinning). Although the best cone and seed quality and the largest cone and seed mass per tree were recorded in the heavily thinned stand, no significant differences were found between heavy and moderate thinning stands (750 trees per hectare). At the stand level, the moderately thinned stand had the highest basal area, stock volume and seed cone production per stand. Our results suggest that thinning to 750 trees per hectare will improve timber and cone productivity in 40-year-old P. koraiensis stands. 相似文献
5.
Kazuhiko Masaka Hajime Sato Hiroyuki Torita Hirokazu Kon Minoru Fukuchi 《Journal of Forest Research》2013,18(6):475-481
To evaluate the effect of thinning on a mature coastal Pinus thunbergii Parlat. forest in Hokkaido, northern Japan, we established four study plots with different thinning intensities (control and 20, 40, and 60 % thinned at individual base; each 20 m × 20 m) and monitored them for 10 years. Radial growth of individual trees in the 60 % thinned plot was significantly greater than that in the other plots, whereas height growth in the 60 % thinned plot was significantly lower than in the other plots. Applying the height growth contribution index, which represents the trade-off between relative height growth rate and relative diameter growth rate, revealed that individual trees in the control and weakly (20 and 40 %) thinned plots had invested more in height growth compared to trees in the 60 % thinned plot. Though higher trunk slenderness value (>80) indicates higher susceptibility to meteorological disturbance such as wind storm and heavy snow, trunk slenderness in the control and the weakly thinned plots increased significantly compared to that in the 60 % thinned plot. In this study, 44.3 % of trees in the control plot had trunk slenderness values >80 over a period of 10 years. The number of trees with trunk slenderness values >80 also increased in the weakly thinned plots. In contrast, no increase was observed in the 60 % thinned plot. In Japan, the thinning intensity is legally supposed to be <35 % of stand volume, which is not enough to improve tree architecture in terms of trunk slenderness. 相似文献
6.
为培育巨尾桉大径材,对造林密度为1650株·hm-2的10年生巨尾桉,开展二次间伐试验,首次间伐在造林后3 a进行,第二次问伐在第1次间伐后3 a进行,分别设置间伐株数2/3、1/2、1/3及不间伐(对照)4种间伐强度处理,采用随机区组试验设计.分析不同间伐强度对巨尾桉林分胸径、树高、单株材积、林分蓄积和经济效益的影响.结果表明:第2次间伐保留密度为645株·hm-2的林分,其平均胸径23.6 cm、立木单株材积0.552 5 m3、林分蓄积356.379 m3·hm-2、经济效益为293 385元·hm-2,分别比对照增加21.2％、54.2％、5.2％、28.4％,均优于其他不同处理.表明间伐强度以株数1/3为宜,保留密度为645株·hm-2的巨尾桉大径材林分,其胸径、单株材积、林分蓄积量和经济效益达到最大值. 相似文献
7.
生态疏伐对华北落叶松林分结构和生物多样性的影响 总被引：1，自引：0，他引：1
森林抚育对调整林分结构、促进林木生长都具有极大作用。为了解抚育对华北落叶松林分结构和林下物种多样性的影响,以承德市第三乡林场华北落叶松—白桦混交林为研究对象,采用对比分析的方法,对生态疏伐前后的林分结构、径阶分布和生物多样性进行了探讨。结果表明:生态疏伐后林分平均胸径增加2.1cm,平均树高稍有变化,林分密度从疏伐前的1 365株/hm~2下降到900株/hm~2;生态疏伐前,直径分布曲线呈左偏,6~16径阶林木数量占总数的42.6%;疏伐后,6~16径阶林木株数占总株数的21.3%,直径分布稍向右偏,更趋于正态分布;疏伐后,林下物种的Simpson和Shannon-Wiener指数均有所增加,Pielou均匀度指数在1号、4号、5号样方内有所下降,2号、3号样方内呈增加趋势,且3号样方的Simpson、Shannon-Wiener和Pielou均匀度指数涨幅均最大,分别比抚育前增加了0.373、0.834和0.203。 相似文献
8.
[目的]研究不同强度采伐下马尾松的生长动态,筛选适宜的采伐强度,为马尾松人工林近自然经营提供技术支撑。[方法]2007年10月在14年生马尾松人工林(保存密度1 100株·hm~(-2))内进行采伐试验,设置4个采伐强度,即保留密度分别为225、300、375、450株·hm~(-2),以不采伐为对照;其后,自2008年开始连续8 a,每2 a测定1次马尾松的胸径、树高、枝下高和冠面积等生长指标,并计算单株材积和林分蓄积量,应用方差分析和Duncan多重比较分析生长指标对不同采伐强度的动态响应。[结果]表明:采伐强度显著影响林分生长,其中,林分平均胸径、单株材积、冠面积的年均增长量随保留密度增大而减小,但均显著高于对照(P0.05)。采伐后第1 3年,马尾松冠面积增长量显著高于采伐后期,胸径则在采伐后第3 5年最高,而不同采伐强度对林分树高生长影响不明显。保留密度显著影响林分枝下高和蓄积量的动态变化,其年均增长量随密度增大而递增。5个处理间林分蓄积年均增长量的差异随林龄的增大而逐渐缩小。[结论]马尾松人工林生长对不同强度采伐的动态响应以树冠最敏感,冠面积首先陡然增大,进而引起胸径的快速生长。树高和枝下高在采伐后年均增量变化相对平稳。4个采伐强度均显著促进单株材积生长,而仅保留密度为225株·hm~(-2)的采伐对林分蓄积增长量影响显著。综合比较林分的单株材积和林分蓄积连年增长量,建议在桂西南15年生马尾松人工林近自然经营中宜选择300株·hm~(-2)的保留密度进行采伐。 相似文献
9.
西江林业局尾巨桉人工林一元材种出材率表编制 总被引：1，自引：0，他引：1
在广东省西江林业局尾巨桉无性系人工林中选择并设置70个标准地,分别进行林分因子调查,同时选择163株样木以2.0 m或2.6 m段材长分径阶进行样木伐倒造材,以实际经济材造材出材率为基础拟合并选择较优的单株木一元材积比方程,然后根据材积比方程进行理论造材并编制尾巨桉单株木一元经济材出材率表;接着利用单株木一元经济材出材率表对所调查的标准地进行理论造材,以林分理论造材出材率为基础拟合并选择较优的林分一元材积比方程,最后根据材积比方程研制尾巨桉林分一元经济材出材率表。所编制的数表均符合国家精度检验标准,可为本地区桉树生产经营提供参考。 相似文献
10.
Competition for light, water and nitrogen between hazel trees and cocksfoot grown under the trees was studied in two hazel
plantations managed in different ways. The first plantation with a light transmission of at least 70% at grass level was compared
with two control hazel and cocksfoot monocrops. The soil was a calcareous heavy clay, 1.4 m deep. Water stress during summer
was severe in the intercropped stand as well as the grass- only plots, while it was much less in the sole stand of trees (without
grass). Hazel tree water potential in the intercropped stand improved in the fourth year as the trees extended their roots
similarly to the grass-free ones, despite their much lower canopy growth rate. The fourth year, local N fertilisation began
to be effective as evidenced by the N content per leaf area unit and growth of the intercropped trees: grass root competition
was high and root barriers were needed to exclude it. The second plantation was managed on a deep soil with a water table
at approximately 2.5 m depth. The trees did not suffer from the presence of grass, and allowed a 15 to 75% light transmission
rate. A control monocropped grass plot was established for comparison. On the basis of the multiple limitation hypothesis,
a grass dry matter production model was built which accounts for radiation transmitted to the understorey, water supply, temperature
and air moisture deficit in interaction with the radiation transmission rate (r2 = 0.716; 590 observations). The limits of
such models are discussed with regard to insufficient knowledge on root dynamics.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
Xiangdong Lei Yuanchang Lu Changhui Peng Xiaopeng Zhang Jie Chang andLingxia Hong 《Forest Ecology and Management》2007,240(1-3):165-177
Analyzing and understanding the structure and growth dynamics of semi-natural plantations is useful for their management. Since 1987, 16 plots with 4 treatments (CT: control; LT: light thinning; MT: medium thinning; and HT: heavy thinning) by 0, 20, 30 and 40% of basal area removal, respectively, and four replications were established in semi-natural larch-spruce-fir forests in northeast China. The structure and growth dynamics of semi-natural larch-spruce-fir stands and the effects of thinning on the growth, structure and diversity were examined. A mixed model repeated measures analysis of variance (RMANOVA) was used to test the effects of treatment and time.
Results showed that differences in periodic annual increment (PAI) of stand basal area and volume and the individual diameter and volume among treatments changed over time in a complex statistical interaction. Thinning, however, had a significant effect on growth at tree and stand levels 12 years after thinning while the PAI of the diameter, basal area and volume was positively correlated with thinning intensity. No significant differences were found in the total stand yield among treatments. Composition of tree species group (larch, other conifers and deciduous trees) during monitoring years did not change significantly. Moreover, no significant differences were observed in tree species and size diversity among treatments in the years following thinning. Both thinning and control plots had similar understory plant diversity after the 12 year period. Univariate point pattern analysis revealed that clumped and random distributions were dominant for tree species groups in this study. The current species composition and regeneration dynamics within these semi-natural plantations suggested a development towards mixed coniferous and broad-leaved forests. Management implications for the transformation from larch plantations towards mixed broad-leaved Korean forests with a more diverse structure, the climax vegetation in this region, were discussed. 相似文献
12.
《Scandinavian Journal of Forest Research》2012,27(1-4):203-214
The paper presents and tests a method for comparing real thinning with strip roads and a simulated selective thinning pattern without strip roads in the same tree stand. The simulation method includes growth models for single trees, and a computer program for carrying out different selective thinning patterns. Simulation proved to be a more reliable method than the simple comparison between the stand growth on 15 m wide zones including and excluding the strip road. The method reduces the effects of random and systematic differences, especially on the small experimental plots. The material of young and middle‐aged Norway spruce stands (19 plots) showed that the growth loss is 0–10% during the first ten years, depending on the width of the strip road and the density of the stand. 相似文献
13.
间伐对人工林生长及木材质量具有重要影响。在浙江开化开展了间伐强度（强度、中度和对照）和间伐方式（间伐1次,间伐2次）对杉木人工林生长及出材量等的影响研究,第1试验区大径材培育林分在第7年和第14年进行了2次间伐,第2试验区中径材培育林分仅在第12年时进行1次间伐。结果表明：22年生大径材培育林分和19年生中径材培育林分不同间伐处理之间树高、总断面积的差异均不显著。间伐显著增加了林木胸径的生长,大径材培育林分强度和中度间伐处理的平均胸径分别比对照增加13.78%和9.69%,中径材培育林分强度和中度间伐处理的平均胸径分别比对照增加12.28%和7.02%。间伐显著促进了林木单株材积的增加,2组试验林分活立木材积随着间伐强度的增加而降低,第1试验区22年生林分不同间伐强度之间活立木材积的差异不显著（P>0.05）,第2试验区强度间伐活立木材积显著低于对照（P<0.05）,中度间伐林分活立木材积与对照和强度间伐之间的差异不显著（P>0.05）。2组试验林分总蓄积和出材量也随着间伐强度的增加而降低,二者在3种间伐处理之间均没有显著差异（P>0.05）。间伐强度不能有效增加林分活立木材积和林分出材量,间伐次数对林分出材量及出材规格有重要影响。试验区杉木大径材培育以2次间伐,总间伐强度50%左右较为适宜,而中径材培育则以1次中度间伐（约25%）为宜。 相似文献
14.
2008年通过对禄丰村林场徐家山林区具有代表性的25 a生塘播云南松人工用材林进行本底调查,依据云南松的林分密度、林木平均胸径、云南松单株林木平均占据的面积和云南松的枯立木百分比等判断该林分为云南松的劣质低产用材林,确定抚育间伐是该林分改造的主要措施。选择相似立地条件的林地,在同一坡向(SE)分别以1 hm2为间伐单位,设置4个研究区,分别设为3块样地及1块对照样地,以研究区内原有林木株数控制进行间伐,间伐的强度样地分别为40%(样地1)、30%(样地2)、20%(样地3)和0%(对照),每个研究区选择林木生长均匀的900 m2(30 m×30 m)作为长期调查研究的标准样地。间伐结束进行第2次调查,1年后进行第3次调查。结果表明:处理1～3间伐前后林木胸径与对照相比,无论其平均值、最小胸径或林木的胸径集中分布范围的下限,均得到了明显的提高,胸径分布较为均匀。云南松的林分质量也相应的得到了提高,达到了间伐的效果。对照样地仅实施下层灌草清理和对部分天然更新的阔叶树伐除,故其云南松林木株数的胸径仍呈左偏态分布,胸径分布极不均匀,林木胸径的分布仍处于自然松散的状态。云南松间伐后,不但林木的胸径得到了普遍的提高,其平... 相似文献
15.
《Scandinavian Journal of Forest Research》2012,27(6):470-488
The main objective of this case study was to explore the possible influence of forest management on the levels and distribution of biomass and carbon (C) in even-aged stands of Norway spruce [Picea abies (L.) Karst.] in Denmark. Data originated from a long-term thinning experiment and an adjacent spacing experiment at stand ages of 58 and 41 years, respectively. Biomass of 16 trees from different thinning and spacing treatments was measured or partly estimated, and soils were sampled for determination of C stocks. All trees in each plot were measured for stem diameter and some for total height, to allow for scaling-up results to stand-level estimates. For trees of similar size, foliage biomass tended to be higher in the spacing experiment, which was located on slightly more fertile land. Foliage biomass increased with increasing thinning grade, but the effect could not be separated from that of tree size. At stand level, foliage biomass tended to increase with increasing spacing as well as with increasing thinning grade. For branchwood, stems and roots (including below-ground stump), the biomass increased with increasing tree size and stand volume at tree and stand level, respectively, but no differences between stands, spacings or thinning grades were observed, apart from that expressed by tree size or stand volume. At stand level, C stocks of all biomass compartments decreased with increasing thinning grade, while the distribution between compartments was hardly influenced. The ratio between above-ground and stem biomass was about 1.21 at stand level, while the ratio between below- and above-ground biomass was about 0.17. Thinning influenced the C stock of the forest floor and mineral soil oppositely, resulting in no effect of thinning on total soil C. 相似文献
16.
Miren del Río Rafael Calama Isabel Cañellas Sonia Roig Gregorio Montero 《Annals of Forest Science》2008,65(3):308-308
The effect of different thinning intensities on growth and yield was studied in Pinus sylvestris L. stands at the south-western limit of its distribution area (Central Spain), using five long-term thinning trials. Data were analysed collectively considering several factors (trial, block, plot and period) as random effects. Total volume and volume increment decreased with thinning intensity, this loss being more significant in the case of moderate and heavy thinning. No difference was found among treatments for total basal area or the increment in basal area. The results revealed an optimum basal area (Assmann’s definition) between 85 and 100% of the basal area in unthinned plots. Volume growth loss associated with heavy thinnings (reduction of 18% in volume increment) was smaller than that reported in Central and Northern European regions (greater than 25%). Height increment was not influenced by thinning, whereas dominant and quadratic mean diameter increments increased with the thinning intensity. The response of diameter growth to thinning was greater at younger ages (less than 50 y) and in medium-sized trees. 相似文献
17.
18.
Restoration thinning and influence of tree size and leaf area to sapwood area ratio on water relations of Pinus ponderosa 总被引：1，自引：0，他引：1
Ponderosa pine (Pinus ponderosa Dougl. ex P. Laws) forest stand density has increased significantly over the last century (Covington et al. 1997). To understand the effect of increased intraspecific competition, tree size (height and diameter at breast height (DBH)) and leaf area to sapwood area ratio (A(L):A(S)) on water relations, we compared hydraulic conductance from soil to leaf (kl) and transpiration per unit leaf area (Q(L)) of ponderosa pine trees in an unthinned plot to trees in a thinned plot in the first and second years after thinning in a dense Arizona forest. We calculated kl and Q(L) based on whole- tree sap flux measured with heat dissipation sensors. Thinning increased tree predawn water potential within two weeks of treatment. Effects of thinning on kl and Q(L) depended on DBH, A(L):A(S) and drought severity. During severe drought in the first growing season after thinning, kl and Q(L) of trees with low A(L):A(S) (160-250 mm DBH; 9-11 m height) were lower in the thinned plot than the unthinned plot, suggesting a reduction in stomatal conductance (g(s)) or reduced sapwood specific conductivity (K(S)), or both, in response to thinning. In contrast kl and Q(L) were similar in the thinned plot and unthinned plot for trees with high A(L):A(S) (260-360 mm DBH; 13-16 m height). During non-drought periods, kl and Q(L) were greater in the thinned plot than in the unthinned plot for all but the largest trees. Contrary to previous studies of ponderosa pine, A(L):A(S) was positively correlated with tree height and DBH. Furthermore, kl and Q(L) showed a weak negative correlation with tree height and a strong negative correlation with A(S) and thus A(L):A(S) in both the thinned and unthinned plots, suggesting that trees with high A(L):A(S) had lower g(s). Our results highlight the important influence of stand competitive environment on tree-size-related variation in A(L):A(S) and the roles of A(L):A(S) and drought on whole-tree water relations in response to thinning. 相似文献
19.
刘友多 《中南林业调查规划》2010,29(3):56-60
对闽南山地柚木人工林开展不同强度疏伐试验,结果表明,在Ⅲ类立地和初植密度1335株,hm2的条件下,7．5a生左右时即可开始进行疏伐;在疏伐强度10％-40％范围内,随着疏伐强度的加大,林分生长量、土壤肥力、光合作用强度等也趋于提高。根据生产实际,若以年均树高生长量达1．3m、胸径达1．5cm以上为目标,并结合生态效益,则适宜的首次疏伐强度为20％～40％,保留密度为750～1000株/hm2。 相似文献
20.
不同密度管理措施对杉木林分的生长、生态效应的研究 总被引：11，自引：1，他引：11
通过定位观测，对不同密度杉木林的树高、胸径与材积生长规律、林分结构、林木分化和材质的差异；并对不同方式间伐后林分的生长变化，以及不同间伐强度对林地土壤肥力、林下植被种类和数量的影响及其经济效果进行了研究。结果表明：林分密度和间伐强度对杉木树高生长无显著影响，而胸径和单株材积则随着林木株数的增加而减小；林下植被种类、数量和土壤肥力均随着间伐强度的加大而有所增加；中度间伐强度的生长、生态和经济等综合效果最佳。 相似文献