乐东县林木苗圃发展的探讨

近年来,林木种苗在绿化宝岛建设等方面发挥了巨大作用,因此海南各地苗圃无论是在数量上还是规模上得到了空前发展。然而如何立足自身条件进行科学、规范经营苗圃,如何使苗木产业走上可持续发展的良性轨道,亟待研究。文中通过对海南省乐东县苗圃现状及发展的探讨,对苗圃的发展提出了意见与建议。     

黑龙江省主要杨树纤维用材品种纸浆性能综合评价

选择黑龙江省7个主要杨树纤维用材品种为研究对象,测定了木材纤维形态、化学成分和成浆性能,分析了林龄与主要纸浆性能间的相关关系,对7个品种纸浆性能进行了综合评价。试验结果表明:7个品种的纤维长度为0.88～1.17mm,纤维素含量为49.28%～59.77%,粗浆得率为50.41%～54.97%,上述指标均达到或超过优质纸浆标准;林龄与纤维长度、纤维素含量和粗浆得率间无显著相关关系;纸浆性能综合评价由高至低的顺序为黑青杨>小青黑>银中杨>大青杨>青山杨>小黑杨>迎春5号。     

对超长悬空钢索弹性模量的测试与讨论

通过对双绕索超长试件的伸长、拉力及绳与丝的径向收缩率的测试,得出:1.在悬索两端无位移的条件下,悬索的弹性模量E_s与悬索长度无关;2.以新钢索作试件(未进行超拉力的拉紧)时,E_s的修正系数γ值为0.37—0.414;3.对较新钢索按程序进行预拉紧后,γ值为0.605—0.715;4.E_s与拉力呈正比,与拉力安全系数呈一元二次曲线;5.对文献[6]的E_s理论值中的W计算式进行推导,W式计算值较试验平均值小2％,用[2]理论式可得E_s准确值;6.对E_s的选取,小跨距(100m左右)的承载索,为0.37—0.414E,大跨距(500m左右)承载索为0.615—0.715E为宜。     

基于生态环境功能的透水性沥青路面设计研究

针对传统的非透水性路面的生态性缺陷,探讨透水性沥青路面在城市道路中的设计及应用。基于减小地表径流及蒸发降温等生态环境方面因素,设计透水性沥青混和料的目标空隙率及路面厚度;并对透水性沥青混和料的配合比设计进行研究,为透水性路面的设计及其推广应用提供借鉴。     

A study on the shade tolerance ofMuehlewbeckia complera

Muehlewbeckia complera was introduced to China in 2002 as indoor-hanging ornamental foliage plant. The experiment of the shade tolerance for this species was carried out in different light intensities (0.14–946.00 μmol·m⁻²·s⁻¹). After 40 days in experimental areas, leaf photosynthentic characteristics indexes ofM. complera in different photosynthesis active radiation (PAR) were measured with LI-COR6400 apparatus, such as the light compensation point, light saturation point, and maximum net photosynthesis rate, at the same time, the increments of total leaf area and leaf amount were measured. The results showed that the optimum light intensity range forM. complera was from 9.26 μmol·m⁻²·s⁻¹ to 569.00 μmol·m⁻²·s⁻¹ (463–28150 lx, relative humidity (RH) for 46–60%, temperature at 16–22°C). Under this condition, leaf photosynthetic efficiency was tiptop. AlthoughM. complera belonged to the moderate sun-adaptation plant species, the plant growth was inhibited when PAR increased to the level of 569.000 μmol·m⁻²·s⁻¹ or above.M. complera could sprout new leaves in photosynthesis active radiation of 0.16–19.22 μmol·m⁻²·s⁻¹ (8–961 lx), or 10 μmol·m⁻²·s⁻¹ for above 6 h. Foundation item: This study was supported by the Research Foundation of Northeast Forestry University. Biography: YUE Hua (1962-), female, Associate professor in Northeast Forestry University, Harbin 150040, P. R. China. Responsible editor: Zhu Hong     

长白山阔叶红松林冠层透射率的定点观测研究

根据长白山阔叶红松林林上和林地太阳辐射的定点观测结果 ,计算了 5月 2 2日— 10月 14日的林冠透射率 ,发现林冠定点透射率与天空状况有关 ,阴天时透射率的日变程曲线比较平稳 ,少云天波动增加 ,晴天条件下波动最为剧烈 ,这种差别是由林窗和太阳辐射中直接辐射的比率不同而产生的。然而通过 2d定点测定与游走测定的比较发现 ,两种方法测定的透射率日平均值差异不大 ,定点测定的日平均值能较好地代表林冠的透射率特征。定点透射率的日变程曲线还随着生长季进程而变化 ,不仅透射率大小发生变化 ,透射率峰值的出现时间也发生更迭。在观测期间内 ,定点透射率日平均值的季节变程曲线呈U形 ,5月底和 10月上旬较高 ,7— 8月较低且平稳 ,随日期 (季节 )的动态变化符合四次多项式函数 ,反映了冠层叶面积的季节变化特征。     

论先秦时期我国的竹资源及利用

根据历史文献和考古资料,考证了我国史前时期、夏商周时期竹林资源的分布,论述了先秦时期在生产、生活、文化、兵器等方面对竹资源的开发利用.     

长白山森林的采伐更新方式

This paper discussed the characteristics of degenerated forest ecosystems in Changbai Mountain area,which include over-harvest natural forest,typical secondary forest,derived forest,and artificial forest.Forest cutting and regeneration methods that were historically used in the region were summarized.They lnclude diameter-class selective cutting,clearcutting,upbringing selective cutting,and selective sutting.We proposed cutting methods for the broad-leaved Korean pine mixed forest,spruce-fir forest,and larch forest.The measures for restoring the original mixed forest ecosystems were recommended.     

京郊农田防护林景观生态评价--以北京大兴县北藏乡为例

Based on theories of protective forests and landscape ecology, the reasonableness of structures and patterns of shelterbelt system at Beizang Town, Daxing County, Beijing were analyzed and assessed from the two scales of forest belts and networks, by integrating uses of field investigation, GIS and RS techniques. Results showed that the existent main belt (3-12 m in width) was too narrow, while the assistant belt (3-27.1 m in width) was too wide; the species composition of the existent shelterbelts was single, and the structures and patterns of the shelterbelt system were unreasonable. It is suggested that the structure of the main and the assistant belts should be changed, such as increasing the width of main belts, decreasing the width of assistant belt, and planting more mixed species, and the pattern with arbores in the middle and shrubs in the sides of belts could be taken into account. For the landscape structure of forest network after regenerating or reconstruction, the grid number of closed network should be 13 per km2 and the minimum number of belts should be 34 per km2, This study also testified that integrating GIS and remote technique with landscape ecology could provide an effective method for reasonable reconstruction of the structures and patterns of shelterbelts system.     

Status of urban vegetation in Guangzhou City

According to a survey for the urban vegetation of Guangzhou, urban vegetation has a significantly difference from natural vegetation because of intense human impacts. The research was conducted in a synthetic survey for soil, species diversity, roadside trees and ecological function of urban vegetation in Guangzhou City. The results showed that: (1) soil densities of urban roadside and park forests were higher than mean density of natural forest soil. The pH values of soil in urban roadside were higher too, and the content of organic matter and the concentration of nitrogen were lower. (2) Species diversity of urban vegetation was lower. The most number of species was only 16 species in tree layers of urban forest. (3) Tree growth was limited by narrow space in high-density urban area, where the trees with defects and disorders were common. (4) Comparing with mature natural forests, the productivity of urban vegetation was lower. The effect of urban vegetation on balance of carbon and oxygen were influenced by the low primary production of urban vegetation. Therefore, the growth condition for urban vegetation should be improved. Biodiversity, primary production and ecological function should be increased for urban vecletation in order to improve urban eco-environment.