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131.
白桦胸径和材积生长率相关关系的研究 总被引:1,自引:0,他引:1
根据地位指数的大小将白桦林分划分为好、中、差3个类型,通过没类型样地上的解析木资料分析,证明白桦的胸径和材积生长率存在关良好的相关关系。经过优选,建立了不同类型白桦林分的胸径与材积生长率相关模型,并依此编制出白桦一元材积生长率表,为准确预测白桦积生长率提供了理论上的依据。 相似文献
132.
根据树干断面积和干长的量测误差对材积计算的影响,探讨了角规测树时胸高断面积和形高的测定误差对林分蓄积的影响,提出了角规两维点抽样法。特点是既能减少的工作量,又能取得满意的测树效果。计算机模拟实验证明了该方法的可靠性。 相似文献
133.
134.
Guillermo Trincado V. Raúl Quezada P. Klaus von Gadow 《Forest Ecology and Management》2003,180(1-3):443-451
The study compares two methods of stand table projection based on data from young Eucalyptus nitens (Maiden) plantations in Chile. The projected diameter distributions were estimated using the methods proposed by Nepal and Somers (1992) [For. Sci. 38 (1992) 120] and Cao and Baldwin (1999) [For. Sci. 45 (1999) 506]. The evaluation compared the observed and estimated diameter distributions for different projection intervals, using the Kolmogorov–Smirnov test and an error index called ‘relative discrepancy’. The evaluation showed that both methods are suitable for application in the Eucalypt plantations. However, the method proposed by Nepal and Somers proved to be more accurate, especially when the projection period extends over 4 years or more. Expected error and bias for the observed and estimated total and merchantable volumes at stand level were also evaluated. The observed error and bias were relatively low for both methods; however, some differences were detected when the volume distributions were analyzed at diameter class level. 相似文献
135.
136.
《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
137.
通过对甘肃省天然林区5次森林资源连续清查蓄积量及用材林蓄积量变化的分析,初步得出结论:1979-1988年甘肃省天然林区蓄积量为增长阶段,1988-1996年蓄积量属减少阶段,1996-2001年为增长阶段。通过对3个阶段的分析,说明甘肃省20多年来,天然林区蓄积量呈波浪式的增长、减少、再增长趋势,也充分说明了国家实施天保工程的正确性。 相似文献
138.
ABSTRACT Separate volume regression equations for pulpwood, sawtimber and over-mature Eucalyptus grandis are presented. An investigation of Schumacher and Hall's volume equation indicated that a better fit may be obtained by adding a constant to the dbh as predictor variable. The resultant equation is: log V = ?4,2328 + 1,7154 log (D-2) + 1,1070 log H. 相似文献
139.
红点唇瓢虫、湖北红点唇瓢虫、细缘唇瓢虫、中原寡节瓢虫是樟白轮蚧 ( Aulacaspis rosarum ) 的4 种捕食性天敌, 本文以检索表形式区分它们的成虫和幼虫。 相似文献
140.
尾叶桉人工林二元材积表的研制 总被引:3,自引:0,他引:3
通过收集福建省永安市不同林龄、立地、密度的尾叶桉人工林林分的样木资料,采用多模型优选法和逐步回归法研制尾叶桉人工林二元立木材积表,并用相关指数、剩余标准差、平均系统误差、平均相对误差绝对值、预估精度作为评价指标,应用灰色关联分析法建立综合评价指数,评价模型优劣。经检验,所编的材积表完全符合生产上的精度要求,且理论基础扎实,编表结果可靠,可在森林资源调查中推广应用。 相似文献