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181.
福建省漳平五一林场马尾松种子园球果常见的害虫有16种,隶属4目12科。其中微红梢斑螟、松实小卷蛾、油松球果小卷蛾和芽梢斑螟是影响良种产量的主要害虫。主要危害嫩梢、花芽、雌雄花、球果、种子等,使球果产量降低。采用营林措施和辅以“佳多频”振式杀虫灯进行防治,可有效地降低虫口密度,达到防治效果。  相似文献   
182.
The development of cracks and changes in appearance have been investigated on radial and tangential sections of pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) after exposure outdoors for 61 months. The degradation of the sections has also been studied at the micro-level. The annual ring orientation was the most important factor affecting crack development on weathering. After 61 months of outdoor exposure, the tangential sections of spruce had 1.7-2.2 times greater mean total crack length per area unit than the corresponding radial sections. In pine, the total crack length per area unit on the tangential sections was 2.2-2.6 times greater than that on the radial sections. Tangential and radial sections show the same colour change as a result of weathering. Tangential sections have more and deeper cracks than radial surfaces. The cracks on the tangential sections occur frequently in both earlywood and latewood. On radial sections, cracks occur primarily at the annual ring borders, but to a certain extent also in the earlywood. Decomposition of the cell wall takes place in both radial and tangential cell walls, and cracks tend to follow the fibril orientation in the S2-layer of the cell wall. The radial cell wall of the earlywood has a large number of pits which are degraded at an early stage.  相似文献   
183.
The cutting technic for thePinus elliottii plantation of the multi-benefit management pattern in the hilly region of Jiangxi Province was studied by establishing the model of growth progress according to Richards function and simulating the tending cutting on computer by use of dynamic programming. The results showed that the best time for the initial thinning was at tree age of 8–10 and final cutting was at tree age of 25. The optimal thinning project was 3 times of thinning cutting including the first thinning, and the thinning time was at tree ages of 8, 12 and 16, respectively. Their thinning intensities were separately 950, 700 and 300 trunks per hectare, and the preserved density was 550 trunks per hectare until the final cutting Foundation item: This study was supported by Natural Science Foundation of Jiangxi Province (A grant 0330023) Biography: WANG Qing-chun (1970-), male, Ph. Doctor, Senior Engineer in Academy of Forest Inventory & Planning, Jiangxi, Nanchang 330046, P.R. China. Responsible editor: Song Funan  相似文献   
184.
The interaction between understorey plants and trees in a young silvopastoral system was studied in a sub-humid Mediterranean environment with cold winters in northern Greece. The experimental design was a split-split plot with three replications and included: three understorey treatments (grass, legume and control), two tree species (Acer pseudoplatanus and Pinus sylvestris) and two spacings (2.5×2.5 m and 3.5×3.5 m). The competition between herbaceous plants and trees resulted in significant differentiation in tree growth while their spacing did not produce any significant differences. The influence of trees on herbage yield either by plant species or spacing was not significant. During the early stages of establishment, a significant positive correlation was observed between sycamore growth and soil moisture, leaf weight, leaf area and leaf number as well as nitrogen and potassium concentration in leaves. Six years after planting the height increase of the sycamore trees was largest in the control treatment (415%), lowest in the grass treatment (134%) and intermediate (192%) in the legume treatment. Much higher was the increase obtained for the diameter, 161%, 207% and 536% respectively for the grass, legume and control treatments. The Scots pine trees grew faster than sycamore over the course of the experiment. Height increased by 397%, 351% and 400% and diameter by 518%, 443% and 683% respectively for the grass, legume and control treatments. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
185.
根据太行山中南地段油松人工林生长预测、投入产出分析、生态功能分析,提出了该区域油松人工林适宜培育以防护林为主的多育林目标,即以培育油松人工用材林、油松人工水源涵养林、油松人工水土保持林为育林目标,以发挥油松人工林三大效益为目的。  相似文献   
186.
吸水剂在樟子松造林中的应用   总被引:8,自引:0,他引:8  
樟子松人工植苗造林成活的关键在于苗木根系的水分保护。所以,对樟子松幼苗的根系用吸水剂进行适当的保水处理,无疑是会提高造林成活率的。  相似文献   
187.
赵成华  伍德明 《林业科学》1995,31(2):125-131
马尾松Pinus massoniana针叶的挥发物由溶剂提取和真空蒸馏制得。用气相色谱和气相色谱-质谱,由挥发物中鉴定出了20种成分。它们主要是单萜烯、单萜烯醇、单萜烯乙酸酯和倍半萜烯。用正常和剪除触角的雌蛾研究针叶挥发物在马尾松毛虫Dendrolimus punctutas产卵场所选择中的作用。试验表明正常雌蛾在针叶上的产卵量要比剪除触角的高得多。触角电位(EAG)研究表明无论是交配的还是未交配  相似文献   
188.
The effects of j-rooting on water stress and growth of loblolly (Pious taeda L.) and eastern white pine (Pious strobus L.) were examined over three growing seasons in the field. Seedlings were planted in an area with severe herbaceous competition with either their roots planted straight or bent into a j shape. All seedlings were planted with their root collars placed at the soil surface. During the first year j-rooted seedlings consistently had lower water potentials but never statistically significant. Since both treatments were planted with the root collar at the soil surface, this trend was likely due to an initial shallower root system in j-rooted seedlings. In year three no differences in water potential were significant and no trends were evident. Growth did not differ significantly by treatment at any time but, by year three, j-rooted plants were consistently larger for both species.  相似文献   
189.
我国湿地松抗松针褐斑病研究进展   总被引:2,自引:0,他引:2       下载免费PDF全文
湿地松松针褐斑病是我国南方松树上的重要病害,本文综合概述了我国自80年初开始的湿地松抗松针褐斑病的研究,重点介绍了湿地松松针褐斑病的抗病选择和抗病机制的研究进展,并对这些研究作了分析评述,122株抗病单株已被收集,4hm^2抗病湿地松种子园已在省建立,松针褐斑病的抗病机制也作了初步分析。  相似文献   
190.
华南地区松、桉树种外生菌根调查*   总被引:7,自引:0,他引:7       下载免费PDF全文
室外调查结果表明,华南地区的松、桉树种已知有菌根真菌11种,其中彩色豆马勃与多根硬皮马勃为本地区的常见种,可与多种松、桉形成外生菌根。在平均气温达20℃以上,相对湿度达80%以上及有相当降雨量的条件下,子实体产生较多;不同立地条件下,外生菌根菌的分布也不相同。  相似文献   
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