共查询到20条相似文献，搜索用时 125 毫秒
1.
2.
3.
汉寿县1977年引进的杨树无性系中,以欧美杨72、美洲黑杨63、美洲黑杨69表现最好,优势显著,在洞庭湖区很有发展前途。县林科所1978年栽植的这三个无性系,7年生时,72杨平均单株材积1.234立方米,63杨平均单株材积0.974立方米,69杨平均单株材积1.323立方米。目前全 相似文献
4.
5.
从意大利引进的欧美杨无性系74杨及美洲黑杨无性系35杨,4年生材积分别达到0.3031、0.3256立方米,超过对照72杨的16.4%和25%,并超过了它们在意大利的生长量,现已正常开花结实.同时,具有易扦插繁殖、造林成活率高、不感染严重病虫害的优良特性,可以在气候温暖的地区进一步开展无性系区域试验,以便为大规模推广提供科学依据. 相似文献
6.
通过对30个黑杨无性系9年生试验林遗传测定评价,经多性状综合评判,选育出了鲁林2号、鲁林3号和A117等杨树无性系,其材积与对照中荷1号的材积遗传增益分别高出29.5%、41.6%、29.7%,增益显著。 相似文献
7.
8.
《山西林业科技》2017,(2)
以金黑杨无性系1号、2号、3号为试验材料,108杨为对照,在晋北、晋中、晋南进行区域化造林试验,测定6年生时金黑杨无性系的生长量,对比金黑杨与108杨的抗性及材性,并采用隶属函数法进行综合评价。结果表明,金黑杨3个无性系的树高、胸径、材积和抗虫性均高于108杨,且除树高外,其它指标均显著高于108杨;金黑杨1号、2号的抗寒性指标均高于对照,1号的材性最好。综合隶属函数值最高的是金黑杨1号(11.550 1),其次是2号(9.959 8)和3号(8.020 3);108杨的最小,仅为2.292 6.金黑杨3个无性系均是适合在山西杨树适生地区推广应用的高效、高产杨树新品种。 相似文献
9.
湘北平原美洲黑杨无性系的丰产性与遗传稳定性 总被引：1，自引：0，他引：1
对3个地点34个美洲黑杨无性系7年生试验林胸径、树高、材积生长进行多点联合方差分析,结果表明:各性状无性系间、地点间及地点内区组间均存在极显著差异,胸径、材积性状无性系×地点交互效应显著.以材积性状为例,采用联合回归法、生态价法和非参数法3种稳定性分析方法对各无性系在不同地点的适应性与稳定性进行评价,根据Eberhart-Russell模型bi值及无性系×地点交互效应值将34个无性系划分为广泛生境型、优良生境型、不良生境型3类.以各无性系材积主效应值V1及非参数稳定性度量值Si(1)对各无性系的丰产性与稳定性进行综合评价,以中汉17为参照,评选出9个高产稳定型无性系,其中,XL-90、XL-77、XL-75、XL-92、XL-101为5个杂交新无性系. 相似文献
10.
美洲黑杨生长变异与无性系选择 总被引：2，自引：0，他引：2
从美洲黑杨原产地密西西比州、得克萨斯州和路易斯安娜州等地引种了104个无性系,并于1998年春在江苏省泗洪县陈圩林场开展无性系对比试验造林。12年生试验结果表明,来自于密西西比州和得克萨斯州7个产地89个无性系长势较好,路易斯安娜州的15个无性系长势较差。树高、胸径和材积等3个生长性状在无性系间差异极显著,性状遗传力(0.552 3~0.658 7)较高,遗传变异系数(8.26%~31.61%)较大。在入选率为5%,选择强度为2.02条件下,材积生长量的选择增益为50.82%。选择的S3412等5个速生无性系12年平均单株材积生长量为1.021 1 m3,超过对照(CK)品种I-69杨15.05%。 相似文献
11.
12.
木犀科梣属(Fraxinus)三心皮子房的确证及其系统学意义 总被引：1，自引：1，他引：0
木犀科(Oleaceae)属(Fracinus,又称白蜡树属)的一些植物除具有2心皮房外,还具有3心皮子房的变异类型,但在国内外重要的植物分类学和系统学文献中均未承认木犀科和属植物具有3心皮子房。本文对北京和郑州栽植的6种属植物的果实进行了形态、解剖和统计研究,结果表明:(1)某些属植物[青(F.pennsylvanicaMars.var.subintegerrima(Vahl.)Fern.)和美国白蜡树(F.americanaLinn.)]同时存在着两种不同类型的果实:源于2心皮的果实和源于3心皮的果实;(2)源于3心皮的果实少于源于2心皮的果实;(3)源于3心皮的果实3室,柱头3裂,果实有3翅,与2心皮果实(2室、柱状2裂,果实有2翅)明显不同;(4)从果实横切片看:3心皮果实的维管束比2心皮果实的维管束小、细,分布也没有2心皮果实均匀,而且相临维管束常出现合并。上述结果证实了木犀科和属除2心皮子房(2室)外,还具有3心皮子房(3室)的变异类型。 相似文献
13.
14.
15.
《Journal of Sustainable Forestry》2013,32(4):71-72
Abstract TREES ON THE FARM: ASSESSING THE ADOPTION POTENTIAL OF AGROFORESTRY PRACTICES IN AFRICA. Franzel, S. and S. J. Scherr (Eds.). Wallingford, UK, CAB International, (2002). 197 pp. Reviewed by Dr. Florencia Montagnini. 相似文献
16.
Large and severe wildfires are now widespread in the Mediterranean Basin. Fire severity is important to ecosystem properties and processes and to forest management but it has been neglected by wildland fire research in Europe. In this study, we compare fire severity between maritime pine (PS) woodland and other forest (OF) types, identify other variables influent on fire severity, and describe its variation. We sampled contiguous, paired stands of PS and OF cover types – including deciduous and evergreen broadleaves and short-needled mountain conifers – that burned under very high to extreme fire danger in northwestern Portugal. Data on stand characteristics and fire severity metrics were collected in plots along transects perpendicular to the PS–OF boundary. Fire severity was rated in separate for the tree canopy, understorey vegetation and forest floor layers, and then an average (composite) fire severity rating was calculated. Fire intensity inferred from stem char height (adjusted for the effects of other factors) was highest in PS, followed by deciduous broadleaved woodland and short-needled conifer forest. With a few exceptions, all fire severity ratings were significantly different between PS and OF at all sites. Most fire severity metrics and ratings were correlated. The distance for fire severity minimization did not differ between OF types (median = 21 m). Variation in composite fire severity was accounted for by a classification tree (R2 = 0.44) based on cover type (contributing with 51% to the overall explanation), stand variables, aspect, distance to the PS–OF edge and fire spread pattern. Except for a more immediate decline in deciduous broadleaves, fire severity rating was not affected by OF type and tended to decrease in more mature stands and moister aspects. The fire severity moderation from PS to OF was compounded by a dominant pattern of down slope fire propagation into moister topographical positions, exacerbating the fuel effect implicit in the cover type change. The results are consistent with fire hazard and fire incidence studies and support conventional knowledge that advocates the expansion of broadleaved deciduous or evergreen forest as a means to achieve more fire-resilient ecosystems and landscapes. 相似文献
17.
Upgrading of urea formaldehyde-bonded reed and wheat straw particleboards using silane coupling agents 总被引：3，自引：0，他引：3
Guangping Han Changwu Zhang Dongmei Zhang Kenji Umemura Shuichi Kawai 《Journal of Wood Science》1998,44(4):282-286
Reed and wheat straw particleboards bonded with urea formaldehyde (UF) resin were manufactured from two different material configurations (i.e., fine and coarse particles). The board densities were in the range of 0.550–.90g/cm3. The effects of particle size and board density on the board properties were examined. The properties of particleboard produced from fine particles were better than those made from coarse particles. An increase in board density resulted in a corresponding improvement in the board properties. The properties of OF bonded reed and wheat straw particleboards were relatively lower than those of commercial particleboards. Three silane coupling agents were used to improve the bondability between the reed and wheat particles and OF resin. Results of this study indicate that all the board properties were improved by the addition of silane coupling agent. The degree of improvement achieved from each coupling agent was different; epoxide silane was found to be more effective for reed straw particleboard, and amino silane was better for wheat straw particleboard. 相似文献
18.
F. X. Schumacher 《Southern Forests》2013,75(1):21-29
THE effect of certain siIvicultura1 practices on timber quality, namely espacement at establishment, rate of growth as influenced by site factors and thinning regime, pruning and age of the trees when thinned or when the stand is clearfelled, is reviewed. The prospects of improving timber quality by means of tree breeding are also briefly dealt with. Felling and logmaking practices which may affect timber quality and the effect of excessive delays between felling and conversion are discussed. How suitable sawmill practices can improve the quality of saw-timber is described. 相似文献
19.
Kurtis R. Moseley W. Mark Ford John W. Edwards Thomas M. Schuler 《Forest Ecology and Management》2008
To understand long-term impacts of partial cutting practices on stream-dwelling salamanders in the central Appalachians, we examined pooled abundance of Desmognathus fuscus and D. monticola salamanders (hereafter Desmognathus) in headwater streams located within long-term silvicultural research compartments on the Fernow Experimental Forest, Tucker County, West Virginia. We sampled Desmognathus salamanders in 12 headwater streams within silvicultural research compartments that have been subjected to partial cutting for approximately 50 years. We used an information-theoretic approach to test five a priori models explaining partial cutting effects at the compartment-level on Desmognathus abundance and eight a priori models explaining stream reach-scale habitat effects on Desmognathus abundance. Our modeling efforts resulted in the selection of two competing models explaining partial cutting effects on Desmognathus abundance at the compartment-level. The VOLUME model, which incorporated cumulative timber volume harvested within compartments, received the greatest support and indicated that Desmognathus abundance was impacted negatively by increased timber volume removal. The second model, LASTDISTURB, incorporating the single variable of time since last harvest activity, indicated that Desmognathus abundance increased with time since last harvest at the compartment-level. For stream reach-scale habitat variables, the EMBEDDED model incorporating the percent of embedded substrate within streams, received the strongest support for explaining Desmognathus abundance. Our results suggest that long-term partial cutting suppresses Desmognathus abundance, possibly by increasing stream sedimentation and thereby reducing available cover for juvenile and adult salamanders. However, these practices do not appear to have threatened long-term persistence of Desmognathus in central Appalachian headwater streams. 相似文献