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71.
《Scandinavian Journal of Forest Research》2012,27(4):410-423
The effect of site fertility, spacing and mode of regeneration on the survival and stand development of lodgepole pine, Scots pine and Norway spruce was studied in a series of experiments comprising 22 study areas in Finland. After 13-14 yrs, lodgepole pine had a mean survival of 68% in planted and 61% in seeded plots, while Norway spruce had the highest (92%) and Scots pine the second highest survival (82%). The survival of planted lodgepole pine was better the wider the spacing. Best survival was achieved on subdry and dry sites, both with planting and with direct seeding. Dominant height was not affected by spacing, but both basal area and volume at the age of 13-14 yrs were significantly higher the denser the spacing. The average difference in the value of the estimated site index H 50 was slightly under 3 m for the superiority of lodgepole compared with Scots pine. Seeding resulted in site indices almost as high as those of lodgepole planting. 相似文献
72.
贵州喀斯特地区牧草引种试验评价 总被引:10,自引:0,他引:10
对国内外引进的6个禾本科牧草品种,9个豆科牧草品种以及喀斯特地区的4个对照品种,在贵州独山地区进行引种试验。结果表明:各参试品种生长良好,能安全越冬、越夏,一年可刈割5~6次,鲜草产量达36558.2~66450.0kg/hm2,干草产量10771.0~19869.0kg/hm2。综合性状表现较好的依次为鸭茅Totter,Wana,Tuoa;多年生黑麦草Nui,Bronsys;白三叶Alice,C6151,Prop,Pitua,Sustain;百脉根Mareb,Lel。 相似文献
73.
鳞毛蕨(Dryopteris filix-mas)天山云杉林种群结构分析 总被引:7,自引:5,他引:7
以西天山国家自然保护区内1 hm2原始鳞毛蕨(Dryopteris filix-mas)天山云杉纯林临时标准地调查材料为基础,分析鳞毛蕨天山云杉林胸径、树高和年龄结构、种群存活曲线以及基本测树因子之间的相互关系.结果表明:①鳞毛蕨天山云杉纯林种群结构稳定,无论是胸径、树高抑或年龄,均呈现出明显的倒"J"型,属于典型的异龄林林分结构,林木更新良好,在其自维持过程中不断有大量小径木更新补充;②林木株数随胸径、树高和年龄的增大,呈负指数函数或负幂函数递减;③树木胸径和树高随年龄的增大,按理查兹生长曲线递增;④胸径与树高的关系为非线性关系.此外,种群存活曲线总体趋势呈现"凹"型,表明该种群是一个连续更新的种群,在林分生长发育过程主要受到小尺度林冠干扰的影响. 相似文献
74.
75.
《Scandinavian Journal of Forest Research》2012,27(1):50-56
In an attempt to develop a better understanding of the effect of knottiness on the yield of logs for sawn timber products, the present study examines the position and geometrical characteristics of 429 knots found in seven Norway spruce (Picea abies (L.) Karst) middle logs from southern Finland. The raw data used in this study were in the form of coordinates of points located on the knot surface recorded in a cylindrical (R, L, T) reference frame. The data were smoothed using a non linear three‐dimensional model. A curvature analysis of the knot pith was used to differentiate the curved and straight portions of the knots. This analysis made possible calculation of knot angles, symmetry, ovality and volume. The major finding of this study is the uneven distribution of knots around the log circumference. Nearly 50% of the total knot volume was concentrated in one‐third of the log facing the south‐east. Knots were also more prominent in higher portions of the logs studied. These observations support the argument that the uneven distribution of knots offers potential for improving the grade yield of timber sawn from trees harvested in high‐latitude countries. 相似文献
76.
《Scandinavian Journal of Forest Research》2012,27(6):591-604
Coastal spruce forests of central Norway harbour a unique assemblage of epiphytic lichens and are given high priority with respect to conservation of biodiversity. To assess the historical impact of logging during the last 100-150 yrs, 31 remnant stands were studied by means of tree-ring analysis of 2199 trees and the decay stage of 1605 stumps. No stands had been clear-cut, but all had been selectively logged at least twice during the last 150 yrs. Total harvested timber volume ranged from 65 to 409 m3ha-1 (31-124% of present-day standing volume) and the selective logging kept standing volume low (40-200 m3ha-1) during 1890-1930. Present-day stand characteristics were strongly correlated with site productivity and topographic position within the ravine valleys. Low amounts of dead wood at sites with high historical logging activity was the only consistent relationship found after covariance of site productivity, topographic position and deciduous trees were taken into account. The results indicate that old-growth stand characteristics, such as reversed J-shaped age distributions and dead wood in advanced decay classes, can be obtained 100-150 yrs after intensive selective logging. 相似文献
77.
78.
喀斯特民族地区山高谷深、人文社会环境封闭,国家外在制度对其影响难度较大。喀斯特民族地区协调有关当事人之间的土地利用关系,主要靠自发形成的农地习俗元制度。在对贵州省典型喀斯特民族地区——关岭县木工村的农地习俗元制度进行调研的基础上对其进行研究。结果发现该地区的农地习俗元制度有着丰富的、独特的内容。 相似文献
79.
通过在砚山县铳卡农场对圣诞树、滇合欢、新银合欢、刺槐4个树种不同造林密度、施肥措施、苗根处理方式及苗期喷云大-120等5个因素的对比试验,幼树期的结果表明树种对林木生长量及生物量的影响最大,施肥措施和苗根处理方式对林木的生长发育也具有一定的作用,而苗期喷云大-120对定植后林木的生长发育作用不明显,密度效应除圣诞树外其他3个树种还不显著。参试的4个树种中,圣诞树3年生时已经郁闭,其最佳技术组合A1B1C1D1E1的树高、地径、冠幅和单株生物量分别为5.05m、4.72cm、1.79m和7.05kg,每公顷可提供薪材22678kg、绿肥和饲料24345.5kg,产值3485.08元;滇合欢的最佳技术组合A2B1C2D2E1的树高、地径、冠幅和单株生物量分别为1.84m、4.33cm、1.23m和1.26kg,每公顷可产薪材6936.8kg、绿肥和饲料1467.4kg,产值767.05元;新银合欢则不太适应试区的气候,每年都受霜冻的危害。预计在滇东南岩溶山区选择多用途的圣诞树和滇合欢,采用最佳的技术措施组合造林,能取得良好的生态效益和经济效益。 相似文献
80.
林冠干扰后,林窗内因小环境的改变使得植被作出相应的反应。1999年对天山云杉林林窗内和林内的植被进行的调查结果表明:在本研究范围内的天山云杉林中,经过林冠干扰后,植被受一定的影响。林冠空隙内丰富度指数均大于林内;36.7%的林冠空隙内个体生态优势度小于林内;76.7%的林内的均匀度指数大于林冠空隙内;66.7%的林冠空隙Shannon个体多样性指数大于林内。林冠干扰前后,各环境因子和植物多样性之间有一定的相关关系。影响林冠空隙内各多样性指数的因子包括海拔、有效N、有机质、全K、全P和总盐,有效N、有机质、全K、全P和总盐对均匀度指数有显著性影响;而影响林内各多样性指数的因子包括坡向、坡位、坡度、光照强度、有效N、全K、全P和总盐,但仅有坡向、坡度、光照强度对生态优势度指数有显著性影响。 相似文献