炼山对二代5年生杉木幼林生长的影响

在福建南平对炼山和不炼山的第2代5年生杉木幼林生长进行对比研究,结果表明,2种处理杉木平均胸径年均生长量均在1.70 cm以上,平均树高年均生长量均在1.00 m以上;炼山处理杉木的生长量略高于不炼山,但它们之间的差异不显著。     

Ten-year responses of ponderosa pine growth,vigor, and recruitment to restoration treatments in the Bitterroot Mountains,Montana, USA

Little is known about ponderosa pine forest ecosystem responses to restoration practices in the Northern Rocky Mountains, USA. In this study, restoration treatments aimed at approximating historical forest structure and disturbances included modified single-tree selection cutting, with and without prescribed burning. We compared the effectiveness of restoration treatments on growth, vigor, and composition of recruitment responses with untreated controls. We used a randomized block design to detect treatment differences in mean individual tree basal area increment (BAInc10), growth efficiency (GE), and recruitment abundance between two restoration treatments (Cut-only and Cut-burn) and a Control. We further examined treatment effects by tree age-class (Young, Mature, Presettlement) using a spatial ANOVA model that incorporates the spatial autocorrelation among trees within experimental units. Ten years after implementing restoration treatments, mean individual tree BAInc10 and GE were significantly higher for treated units relative to Control units; all three age-classes benefited similarly from restoration treatments relative to the Control, with the greatest response in the Cut-only and moderate response in the Cut-burn. When treated units were compared, Cut-burn negatively affected BAInc10 and GE relative to Cut-only. Presettlement trees responded positively to treatment relative to the Control, particularly for BAInc10, demonstrating the potential of these old trees to respond to reduced competition. The Cut-burn treatment, in contrast, negatively affected the BAInc10 and GE response of postsettlement trees when compared to Cut-only. Restoration treatments did not reduce the amount of Douglas-fir recruits. In addition, the recruitment of both ponderosa pine and Douglas-fir species was associated with the proximate cover of woody debris in Cut-only and Control treatments. Finally, special consideration needs to be taken for spring Cut-burn treatments, which appeared to dampen growth and vigor, relative to Cut-only, particularly for Young and Mature trees, and increased recruitment of ponderosa pine and particularly Douglas-fir.     

玉龙县计划烧除存在的问题及改进措施

计划烧除是控制和减少森林火灾发生最有效的手段之一。该文通过分析计划烧除的有益作用和可能带来的负面影响,结合玉龙县实施计划烧除存在的问题,提出了改进措施。     

Review on Causes of Forest Decline

Site degradation and yield decline of forest have attracted increasing attention from forest managers and scientists. Studies conducted by researchers from a variety of disciplines and perspectives have led to a variety of competing hypotheses concerning the causes of the problem. In this paper we review evidence of such a yield decline and examine the problem and its possible way to identify the individual contributions of the many determinants of yield decline, and their interactions.     

免炼山与炼山造林对当年生桉树幼林生长的影响

试验对免炼山与炼山造林对当年生桉树生长的影响进行实地调查。结果表明:免炼山造林不影响桉树当年的生长量,具有操作方法简单,成本较低,符合可持续发展经营的要求。     

东北、内蒙古林区物候点烧技术应用的情况分析

物候点烧技术是我国当前开设防火隔离带、国境防火带,降低林内可燃物载量、预防重大森林火灾最有效的技术之一,得到相关部门高度重视。但近年由于计划烧除时跑火造成森林火灾,使人们对物候点烧技术产生争议。本文是在对东北、内蒙古林区开展物候点烧技术相关事宜进行调查的基础上,总结四省（区）开展物候点烧取得的显著成效,阐述点烧的可行性、必要性,分析跑火的主要原因、存在的问题、解决的办法,并对今后如何加强物候点烧技术的安全性、科学性提出了建设性意见。     

森林可燃物调控技术方法研究进展

基于森林可燃物调控技术方法的国内外研究现状,从森林可燃物调控技术方法、景观尺度上的可燃物处理以及可燃物调控技术的生态效应3个方面进行系统论述。以此为基础,探讨适合的森林可燃物调控的技术方法。建议在进行森林可燃物调控时,应以营林技术为主要手段,加大景观水平的可燃物管理,综合考虑可燃物调控技术方法对生态环境的影响,实现森林可燃物的生态调控。     

Biology and management of Phalaris minor in wheat under a rice/wheat system

Summary Germination of Phalaris minor declined with the increase in duration of imbibition in water from 30 min to 72 h at temperatures above 22 °C . Germination was reduced down to 10 cm and 2 cm soil depth by wheat straw burning in puddled and non-puddled soil, respectively, with maximum reduction near the soil surface. The dormancy of P . minor seed was not more than 60 days under field conditions. In puddled soil, 38–60% of the viable seeds of P. minor remained concentrated in the upper 5-cm layer. Germination decreased with an increase in soil depth. In total, 15% of seeds stored in the laboratory emerged from 10-cm depth, whereas seeds did not germinate below 4.2-cm depth under field conditions. Depth of emergence of P . minor was shallower in zero tillage compared with the conventional method of wheat sowing. The seeds retrieved from rice soils kept under continuous submergence for 60 days exhibited 26% and 57% loss of germination over semi-submergence and semi-wet conditions respectively. There was 100% loss of germination in 10-month-old seeds retrieved from the soil under rice-growing conditions. Plant density of P. minor was lower in zero tillage than with the conventional method of wheat sowing. Cross-ploughing in the upper 2–5 cm of soil (shallow tillage) and drill-sowing of wheat 1 week after shallow tillage reduced germination of P. minor by 44% and 37% and increased grain yield by 21% and 47% over zero-tillage and conventional methods respectively.     

田间焚烧麦秆对玉米种子萌发和幼苗生长的影响

采用水培法研究了麦秆焚烧后的土壤溶液对玉米种子萌发和幼苗生长的影响。结果表明,种子发芽率、发芽指数和胚乳养分的利用率有所减少,但与焚烧前差异不显著;种子发芽势、活力指数和α-淀粉酶活性明显下降。幼苗芽长、苗鲜重和蛋白质合成减少不明显;幼苗主胚根长度、胚根数、叶绿素含量、净光合速率及干物质积累则明显减少。表明麦秆焚烧后的土壤溶液不利于玉米种子萌发和幼苗生长。     

柴油机燃用生物质燃油--柴油混合燃料燃烧特性的研究

在测定生物质燃油物理性能的基础上,将生物质燃油和柴油做各种配比,最后筛选出了生物质燃油柴油(体积比)=19的混合燃料与纯柴油进行了台架对比试验.结果表明在发动机结构不变的情况下,燃用混合燃料1和混合燃料2是可行的,与纯柴油相比节油效果显著,节油率可分别达11.7%和6.6%,并有效降低了柴油机的排放污染,CO2含量分别降低了7.1%和4.5%.