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991.
992.
竹材防霉染色处理的初步研究 总被引:2,自引:0,他引:2
以铜化物、硼化物、新洁尔灭的质量分数为因素,按正交试验方案组成不同配比的复合防霉药剂,分别加入到质量分数为1%的酸性染料溶液中,在一定温度下对竹材进行防霉染色处理;同时测定防霉染色处理竹材与染色处理竹材的色度指数,并评价其变化.结果表明:将该复合防霉剂与酸性大红染液复配,不仅能提高染色竹材的防霉性,而且防霉剂的配比对竹材的染色效果基本无影响. 相似文献
993.
中国紫胶虫(Kerriachinensis)与其它胶蚧一样,均隐匿在其胶被内生长发育,外观难以看到各虫龄期的体形特征。用图表形式把各虫龄期及其相关的泌胶形态和冬夏两代各自所需无数标出,即可清楚看出该虫生活史、生活周期及各发育阶段期间的变化和关系。同时,列出各虫龄期特征检索表,便于在科研与生产中应用。 相似文献
994.
研究森林经营单位级的可持续经营是实现森林可持续经营的基础和保障,也是我国当前森林经营亟待研究的前沿课题.以广东韶关华溪国有林场为例,结合广东省森林资源二类调查和生态状况调查,探讨森林生态功能上的可持续经营指标体系,指出没有生态上的森林可持续,整个林业的发展将是不可持续的. 相似文献
995.
Bijan Payandeh 《New Forests》1991,5(1):1-12
Data from 122 northeastern Ontario plots were used to develop composite site-productivity functions for black spruce (Picea mariana [Mill.] B.S.P.). A logistic model produced the best fit to the data. The resulting equations produce sets of polymorphic site-productivity curves with subsets of three curves, one for each of Ontario's Forest Ecosystem Classification Operational Groups (FEC OGs) 11, 12 and 14. For direct estimates of site productivity, site index was expressed as a function of stand height, age and FEC OG by employing the reciprocal of the logistic model. Application of the resulting equations and tables is demonstrated in an example. The procedures employed may be used to develop ecologically based site-productivity functions for other areas. 相似文献
996.
997.
WANG Shu-li WEN Jing YANG Zhen MA Feng-ming 《林业研究》2006,17(3):255-258
Plot sampling was conducted in the second cultivation areas ofLarix olgensis in Heilongjiang Province, China. By analyzing plot investigation data, wood properties, and kraft pulps of 840 plots and 248 sample trees in industrial plantations of L. olgensis on different sites, we examined the growth process of L. olgensis industrial plantation with suitable structure, the wood fiber feature, chemical composition, physical performance and pulp characteristics. It is suggested that site conditions have major effects on plantation growth, fiber contains, fiber length, rate between fiber length and fiber width, pulping rate and pulp physics intensity. The best site for L. olgensis industrial plantation growth is site class Ⅰ and site class Ⅱ, which are on lower locations. Site condition has an obvious influence on the wood characteristics. Within the range of site conditions and stand densities studied, the worse the site condition, the less the fiber contains, the shorter the fiber length, and the more the 1% NaOH extraction. This kind of relationship becomes more obvious as stand age increases. However, the influence of site condition on pulping rate and pulp physics intensity is not obvious. The result provides theoretical base for cultivation of industrial fiber plantation of L. olgensis. 相似文献
998.
999.
Lennart Noordermeer Terje Gobakken Erik Næsset Ole Martin Bollandsås 《Scandinavian Journal of Forest Research》2021,36(1):55-67
ABSTRACT Forest productivity is a crucial variable in forest planning, usually expressed as site index (SI). In Nordic commercial forest inventories, SI is commonly estimated by a combination of aerial image interpretation, field assessment and information obtained from previous inventories. Airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) data can alternatively be used for SI estimation, however the economic utilities of the inventory methods have not been compared. We compared seven methods of SI estimation in a cost-plus-loss analysis, by which we added the expected economic losses due to sub-optimal treatment decisions to the inventory costs. The methods comprised direct and indirect estimation from combinations of ALS, DAP and stand register data, and manual interpretation from aerial imagery supported by field assessment and information from previous inventories (conventional practices). The choice of method had great impact on both the accuracy and the economic value of the produced estimates. Direct methods using bitemporal ALS and DAP data gave the best accuracy and the smallest total cost. DAP was a suitable and low-cost data source for SI estimation. Estimation from single-date ALS and DAP data and age obtained from the stand register provided practical alternatives when applied to even-aged stands. 相似文献
1000.
G. M. A. Iqbal S. M. S. Huda M. Sujauddin M. K. Hossain 《林业研究》2007,18(3):226-230
A study was carried out to determine the influence of different types of sludges (municipal, industrial and residential) on field germination, growth and nodulation of L. leucocephala seedlings in the nursery. Before sowing of seeds, different combinations of sludges were incorporated with the nutrient deficient natural forest soils. Field germination, nodulation status and physical growth parameters of seedlings (shoot and root length, vigor index, collar diameter, leaf number, fresh and dry weight of shoot and root and total dry biomass increment) were recorded after three and six months of seed sowing. Field germination, nodulation status and growth parameters were varied significantly in the soil amended with sludges in comparison to control. The highest number of nodule was recorded from soil amended with residential sludge ( 1:1 ) and highest fresh and dry nodule weight was also found from the same combination in both three and six month old seedlings. In case of growth parameters, the highest growth was recorded from soil and residential sludge ( 1:1 ) combination compared to control. From the study, it can be recommended that soil amended with residential sludge ( 1:1 ) provide better field germination, growth and nodule formation of L. leucocephala in degraded soil. 相似文献