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21.
栎属植物数量分类初探 总被引:1,自引:0,他引:1
本文根据栋属植物形态特征,木材解剖特征和脂肪酸特征,对栋属植物进行聚类分析,其结果表明:栎属(Quercus L.)植物和青冈属(Cyclobalanopsis)是一个自然种群,应归为1属,建议栎属分为3个亚属,即青冈亚属(Subg.Cyclobalonopsis)高山栎亚属(Subg.suber)和落叶栎亚属(Subg.Quercus).这3个类群无论是在主要特征,还是在次要特征上,都表现出明显的区别,而高山栎亚属和青冈亚属的亲缘关系较近,落叶栎的分化程度较高,进化程度较高。 相似文献
22.
Rom Ogaya Josep Peuelas Jordi Martínez-Vilalta Marta Mangirn 《Forest Ecology and Management》2003,180(1-3):175-184
The present study was carried out to elucidate the drought growth responses of Quercus ilex L., Phillyrea latifolia L., Arbutus unedo L., and other accompanying woody species of the Mediterranean holm oak forest. We submitted holm oak forest stands in Prades mountains (NE Spain) to a 2-year experimental drought. We reduced soil water availability about 15% by plastic strips and funnels that partially excluded rain throughfall and by ditch interception of water runoff. Mean stem diameter increment showed a great variation depending on the species. A. unedo had larger growth rates than Q. ilex and P. latifolia, but it was also the species that experimented the highest growth reduction in the drought plots (77%), suggesting a higher drought sensitivity than Q. ilex (55%) and P. latifolia (no drought effect). The growth reduction was specially marked in the larger trees. Aboveground stand biomass increment, estimated from stem diameter by allometric relationships, was 1.9 Mg ha−1 per year in the control plots. The 15% reduction in the upper soil moisture produced 42% reduction in this biomass increment. In the drier conditions predicted in this Mediterranean area in the frame of climate change, an important reduction of growth rates can be hence expected, accompanied by a gain of dominance of drought-tolerant species such as P. latifolia in detriment of more mesic species such as Q. ilex. 相似文献
23.
Modelling cork oak production in Portugal 总被引:1,自引:0,他引:1
The layout of 32 permanent plots in the most important cork production regions of Portugal and the measurement of the most
representative tree parameters were performed for statistically sound cork weight modelling. The establishment of cork weight
equations is presented for the different cork oak study areas considered alone or grouped according to the most representative
tree parameters. For the presented cork weight models was chosen independent variable the total stripping surface (artmax). For the selection criteria five statistic were used, including PRESS, APRESS and Mallows's statistic. The crossvalidation
of the best classified models was performed and to discuss the importance of the “study area” factor, a regression analysis
with “dummy” variables was performed. 相似文献
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秦岭松栎林带生物量及其营养元素分布特征 总被引:22,自引:2,他引:22
秦岭脱齿栎林、油松林和华山林(包括0-60cm土层)营养元素总贮量达29.2500-390.1739t.hm^-2,其大小为锐齿栎林>华山松>油松林,土壤中营养现贮量占系统总量的93.10%-99.39%,植被层和凋落物层仅占0.57%-3.00%和0.10%-1.99%;3林分乔木层生物量、木材蓄积量和营养元素积累量平均值分别为120.483t.hm^-2,129.384m^3.hm^-2和1226.9kg.hm^-2,锐齿栎林>油松林>华山松林。3林分林下植被层生物量现存量和营养元素积累量平均值分别为1.553t.hm^-2和53.1kg.hm^-2,锐齿栎林最大,华山松林最小。林下凋落物现存量和营养元素积量平均值分别为17.475t.hm^-2和502.5kg.hm^-2,3林分凋落物现存量、营养元素含量及其积累量都存在明显的差异。锐齿栎林、油松林和华山松林营养元素年吸收量、归还量、存留量和平均归还率分别为33.4、147.2和264.3,195.6、66.9和84.1,138.8、80.4和180.2kg.hm^-2和0.585、0454和0.318,3林分各营养元素的年吸收量,归还量和存留量也存在一定的差异,锐齿栎林干和皮中Ca和Mg含量远远高于油松林和华山松林的,锐齿栎林多代连作势必导致营养元素的大量流失,特别是Ca和Mg,会破坏土壤原有离子动态平衡,引起林地土壤理化性质改变,林地生产潜力逐渐下降。 相似文献
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Dylan N. Dillaway Jeffrey W. Stringer Lynne K. Rieske 《Forest Ecology and Management》2007,250(3):227-233
Oaks (Quercus spp.) are experiencing recurring regeneration failures associated with pervasive mid- and under-story strata of shade tolerant species in intact, undisturbed forests. Where oak regeneration occurs, inadequate vertical height and depleted root carbohydrate stores impede the ability of regenerating oaks to respond when light does become available. A variety of silvicultural techniques have been developed to increase the penetration of diffuse light, enhancing the light environment on the forest floor, and thereby increasing the likelihood of regenerating oaks to successfully respond to increased light transmittance. We measured shoot and root characteristics, and root soluble non-structural carbohydrate concentrations of white oak (Q. alba L.) advance regeneration exposed to enhanced light intensities associated with a mid-story removal and a clearcut, and compared white oak regeneration vigor to untreated controls.
Root diameter and soluble non-structural carbohydrates increased with increasing light availability. Our data suggest that white oak responds to increases in light transmittance by building below-ground biomass and carbohydrates in the root system prior to an above-ground response. Our study shows that white oak regeneration vigor increases with only modest increases in light. In the absence of other pressures, enhancing the light environment to the forest floor should contribute to successful regeneration of this species. 相似文献
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以三江平原试验区为背景,采用植物生态场技术开展次生林效应带生态功能模拟,研究结果表明:蒙古栎林6m效应带产生斑块效应,8m效应带出现边缘效应;4m,6m和8m带的光能利用与风流动模式与效应带的分布方位关系密切,根据光能利用效率总结出蒙古栎林效应带依照8 m带→6m带→4m带逐步演化。 相似文献