我国云南红豆杉药用原料林培育技术开发进展     

王卫斌  姜远标  王达明  周云  景跃波 《福建林业科技》2007,34(2):169-173,196

培育红豆杉人工药用原料林既是紫杉醇产业可持续发展的主要途径,也是保护野生资源的有效手段。云南红豆杉紫杉醇含量高,具有较高的药用开发价值。本文系统地阐述了云南红豆杉的资源状况,分析评价了我国云南红豆杉药用原料林培育在良种选育、采穗圃营建、种苗培育、人工林营建与原料采收等关键技术环节所取得的研究进展情况,并针对存在的主要问题,提出了对策建议。  相似文献   

Early growth responses from weed control and planting larger stock of Pinus radiata are greater than that obtained from mechanical soil cultivation     

South  David B.  Zwolinski  Janusz B.  Kotze  Heyns 《New Forests》2001,22(3):199-211

Early growth of two grades ofbare-root Pinus radiata D.Don seedlingswere studied in response to four soilcultivation treatments and two weed controltreatments.Soil cultivation treatments included (i) pitsmade by hand, (ii) pits made with an auger,(iii) ripping alone, and (iv) ripping plusdisking. Weed treatments included (i) manualrelease 1 year after planting or (ii) totalweed control for 1 year involving the use ofherbicides and additional hoeing. Bare-rootseedlings were separated into either medium(4.1-mm average root-collar diameter; height25–31 cm) or small (2.8-mm average root-collardiameter; height 14–20 cm) size classes.Growth on this site was excellent and 7 yearsafter treatment, trees in the least expensivetreatment averaged 12.8 m in height. Use ofmedium seedlings and extra weed controlincreased merchantable volume by20 m³ ha^{minus 1} and 19 m³ ha^{minus 1},respectively. When combined, the increase was39 m³ ha^{minus 1}. However, none of the soilcultivation treatments caused a significantincrease in merchantable volume. Disking onthis site proved to be of no benefit. Aboundary-line analysis was used to examine themarginal returns from investing in intensivesilviculture.  相似文献   

Profiles of forestry contractors and development of the forestry-contracting sector in Sweden     

《Scandinavian Journal of Forest Research》2012,27(4):395-404

Abstract

Contractors perform the majority of forestry activities in Sweden, yet little is known about the development of their company structures and strategies. By analyzing data from the Swedish Forest Agency's yearly survey to forestry contractors for 2006–2009 and comparing the results with previous data for 1993–1998, we examined the current profiles of Swedish forestry contractors and their recent development. For 2006–2009, responses were received from 700 to 770 forestry contractors, corresponding to ca. 20% of the estimated total number of Swedish forestry contractors. In 2009, 60% of contractors were mainly performing logging activities, whereas 30% were mainly performing silvicultural activities. Between 1993 and 2009, the number of contractors increased by ca. 80%, while the number of forestry working contractors and their employees increased by 157%. These increases were mainly due to increased silvicultural activities. Although one-person enterprises still dominate among Swedish forestry contractors, most logging work is performed by small-sized enterprises, whereas most silviculture work is performed by large-sized enterprises. Our study suggests that there is an increased dependency upon contractors and forestry contractors have become more diversified, but still specialized, in the type of work they perform.  相似文献   

Modelling probability of snow and wind damage using tree,stand, and site characteristics from Pinus sylvestris sample plots     

《Scandinavian Journal of Forest Research》2012,27(1-4):348-356

The risk of damage on trees from snow and wind was modelled using tree, stand, and site characteristics from 286 permanent Scots pine (Pinus sylvestris L.) sample plots within the Swedish National Forest Inventory. Three logistic risk assessment models were developed for the county of Västerbotten in the boreal zone of Sweden. The best model, using tree, stand, and site variables, correctly classified 81.1% of the undamaged and 81.8% of the damaged plots. The model over‐predicted the proportion of damaged plots (21.3%), compared to the observed proportion of 3.8%. When evaluating the models using temporary plots from Västerbotten, the model using tree, stand, and site variables showed the best overall predictability. When applied in southern Sweden, the models developed for Västerbotten showed poor predictability. The study shows possibilities for correctly classifying the overall susceptibility to damage from snow and wind if the models are used within their limits.  相似文献   

Carbon balance of a forest ecosystem after stump harvest     

《Scandinavian Journal of Forest Research》2012,27(8):762-773

Abstract

Stump harvest in forests can cause both reductions of CO₂ emissions through a decrease of decomposable substrate (direct effect) and emission increases as a consequence of deep and extensive soil disturbance (indirect effect). Here, the effects of stump harvest on net ecosystem CO₂ exchange (NEE) in a former Norway spruce stand in mid Sweden are presented. CO₂ exchange was continuously followed by eddy-covariance measurements during the first years after harvest. Differences in NEE from stump harvested and mounded (reference) plots were determined by soil-surface respiration measurements. Respiration from decaying stumps was estimated by a decomposition model. Fluxes indicated a direct effect (decreased efflux) during the first year after harvest that corresponded to the absence of decomposing stumps. During the following years, this emission reduction was increasingly counteracted by an indirect effect (increased efflux) of similar magnitude. This means that the expected emissions caused by extra soil disturbance occur with a certain delay and seem to increase with time. By these emissions, the substitution efficiency of stumps as bioenergy resource is reduced. Furthermore, at a time scale of centuries, instant combustion of stumps leads to a larger contribution to global warming than slow decomposition, because the stump carbon is available earlier in form of greenhouse gas. This is estimated by the time integral of emissions. Thus, despite the surprisingly low initial emissions, the overall substitution efficiency and climate benefits of stump harvest are likely to be small. The long-term consequences of stump harvest for the carbon budget are, however, still uncertain.  相似文献   

巨尾桉优良无性系组培苗与扦插苗的造林效果   总被引：1，自引：0，他引：1  

吴培衍 《亚热带农业研究》2006,2(2):94-96

利用巨尾桉无性系组培苗和扦插苗2种苗木进行造林试验,3年多试验表明,组培苗比扦插苗造林成活率高8.17%-9.07%,经方差分析达显著水平;组培苗造林的各项生长指标、抗风倒(折)能力略高于扦插苗,但两者之间差异未达到显著水平。  相似文献   

简评加州私有土地的木材管理     

ClaralynnRoseNunamaker 《浙江林学院学报》1999,16(4):430-438

在加州,私人及私营公司拥有的生产性林地占４５％。为了收获木材,这些林地的业主需要持有执照的专业林业工作者准备一份详细的经营计划,该计划需经州政府广泛的审阅。这种经营计划往往耗资６０００～１２０００美元或更多的资金。计划的准备及州政府的审阅耗时６个月或更长的时间。林业工作者所作的决策受到法律、林地条件、经济状况和林地业主的目的等限制。林业实践法规对造林体系的选择及采伐后要达到 的更新量有详细的标准。  相似文献   

桉树等速生树种光合速率测定分析   总被引：2，自引：0，他引：2  

李志辉  杨模华  黄丽群  杨艳  刘军 《中南林业科技大学学报(自然科学版)》2005,25(2):7-11

在晴天适宜条件下,对邓恩桉Eucalyptus dunnii Maid、樟树Cinnamomum camphora、洋玉兰Magnolia grandiflora等速生树种采用LI-6400 p便携式光合测定系统测定其叶片的光合速率、蒸腾速率、气孔导度、胞间CO2浓度等的日变化.结果表明:邓恩桉、樟树和洋玉兰三者的光合作用日变化均呈双峰型,都存在光合午休现象,邓恩桉与樟树的光合速率高于洋玉兰,且邓恩桉和樟树能充分的利用午后丰富的光热资源,光合午休持续的时间比洋玉兰短.邓恩桉、樟树与洋玉兰3个树种的蒸腾速率日变化基本相似,均呈双峰型,但邓恩桉的蒸腾速率比樟树和洋玉兰的蒸腾速率大.3个树种的蒸腾速率与光合速率间均存在相同的变化趋势.蒸腾速率在很大程度上决定于气孔导度,3个树种的气孔导度与各自的光合速率日变化趋势都有很强的正相关关系.  相似文献   

优良速生树种光皮桦研究进展   总被引：10，自引：4，他引：10  

胡晓媛  李志真  梁一池 《福建林业科技》2006,33(2):159-163

介绍了我国优良乡土阔叶树种光皮桦近年来相关研究进展,包括生物学特性、解剖学特性、育苗及造林技术、种群生态学等,并探讨了其应用前景。  相似文献   

湖南省马尾松飞播林的养分循环研究     

漆良华  庞统  陈晓萍  何友军  李志辉  杨模华 《中南林业科技大学学报(自然科学版)》2003,23(2):26-32

对湖南省3种不同密度类型的马尾松飞播林分的养分循环进行了研究.结果表明:各组分营养元素的含量均以树叶最高,树干最低,在各组分中大量元素以N、K、Ca的含量较高,而P和Mg的含量较低;微量元素以Mn的含量为最高,Cu的含量为最低.单株林木营养元素的积累量随着林分密度的增大而减小,低密度林分营养元素积累量分别是中密度、高密度林分的2.75倍和4.04倍.不同密度单株林木各营养元素积累量依次为N>K、Ca>Mg>P>Mn>Fe>Zn>Cu.随着林分密度的增加,乔木层营养元素的积累量逐渐增大,地被层所积累的营养元素量有减少的趋势.林分年净积累量随着林分密度的增加而增加,各元素的净积累量以N最大,Cu最小.各种元素的吸收量、存留量都随着林分密度的增大而增大.营养元素的循环速率也因林分密度的增大而逐渐变小,并且大量元素的循环速率要高于微量元素.  相似文献