共查询到20条相似文献，搜索用时 562 毫秒
1.
2.
3.
回顾了我国有关红色旅游、红色旅游共生及红色旅游绩效的相关研究并进行了综述。根据文献对相关概念进行了整理,根据研究成果的数量和内容对红色旅游相关研究进行了分析,提出了各发展阶段及各阶段内容特征。对旅游共生的研究内容进行了整理,对红色旅游研究进行了总结,得出了现阶段的发展和未来的展望。 相似文献
4.
从中西方对美学研究和对园林的发展历程出发,分析了中西方园林形式不同的原因,指出了由于认识世界的方法上不同,最终导致对美本身的认识上走了截然相反的道路。探讨了中西方对美学概念的异同认识。 相似文献
5.
由于高速公路建设的加快,对环境的负面影响亦日益增强.分析高速公路建设对生态环境的影响认为,其改变了土地利用现状,对地形地貌产生了重大影响;会造成严重的水土流失;减少了森林资源,危害了生态环境及生物多样性;对环境产生了污染.针对项目的决策、实施和运营等不同阶段提出了相应对策与措施. 相似文献
6.
指出了园林绿化养护的重要性,提出了园林绿化养护中存在的问题,包括对园林绿化养护的认识不足经费不足、缺乏技术含量等,对园林绿化养护监管的主要环节进行了梳理,并分别对草地、绿篱、绿化树木养护的具体措施进行了详细地介绍,以期对园林绿化养护提供有益的参考。 相似文献
7.
分析了道路交通对环境的污染,从噪声污染、对大气的污染、对水和土壤的污染等角度谈了道路交通对环境的影响,并提出了道路交通环境保护的对策。 相似文献
8.
本文对实施天然林保护工程后,充分利用林区山野果的自然资源优势变为经济优势,进行了论述,并对该项目进行了市场预测,着重对项目拟建规模进行了投资估算与财务经济分析,作出了项目综合评价。 相似文献
9.
介绍了美国年度森林资源清查的背景和不同方案的比较,对建立我国年度森林资源清查体系提出了一个建议方案,并对其进行了可行性分析,最后对有关问题进行了讨论。 相似文献
10.
指出了室内主要污染物之一甲醛,对人类的身体健康有着极大的危害。采用高灵敏度INTERSCAN传感器,对室内空气相对浓度含量较低的甲醛进行了测量,通过计算得出最终结论,并对结果进行了分析,提出了治理对策与建议。 相似文献
11.
全国杉木家系区域试验研究 总被引：1，自引：0，他引：1
湖南省林科院先后于 1984年春、 1989年春两次参加全国杉木家系区域试验。方差分析表明 :提供家系的种子园之间以及种子园内家系之间各主要数量因子存在显著差异。对样本观测值进行标准化变换主成分分析 ,求出遗传综合指数 ,再聚类分析评价 :湖南靖州、江西赣南、广西柳州、贵州东南、福建三明、广东曲江种子园提供的家系生长有明显优势。 相似文献
12.
13.
IntroductionDuringthepasttwodecades,studieshaverevealedthatgrowingash(Fnainusmandshurica)andlarch(LarlksPP.)togetherinaproperwaycanincreasetheproduc-tivityQfthestandsI"'}'-'].Theyieldimprovementmechanismsattributetotwoaspects,i.e.,theabovegroundandundergr… 相似文献
14.
《Journal of Sustainable Forestry》2013,32(2-3):115-127
Abstract Seasonal behavior of vascular cambium and development of secondary xylem were studied in the 2-3-years-old branches of Azadirachta indica A. Juss. (Meliaceae) growing in moist deciduous (MDF), dry deciduous (DDF) and scrub land (SF) forests of Gujarat State. Development of xylem began with the sprouting of new leaves in January in both MDF and DDF. Xylem production culminated in July in MDF whereas it reached peak in April and July in DDF. Cambial cells ceased to divide with the maturation of leaves in November and October in MDF and DDF, respectively. Mature xylem and phloem derivatives surrounded the cambium in December in MDF and November in DDF. Radial growth in the branches of trees growing in SF was found continuous throughout the year with peak cambial activity in April, July and November. In all the three forests, maximal radial growth was encountered in July when the rains were heavy. Cambial activity and xylem development showed significant correlation with the phenology of the trees in MDF and DDF whereas cambium was found active throughout the year and no correlation was found between the cambial activity and phenology in SF. 相似文献
15.
In natural ecosystems, nutrition available for plants shows great spatial heterogeneity. Much is known about plant root responses to the spatial heterogeneity of nutrition, but little is known about carbon usage in roots in nutrition-deficient patches and its effect on root longevity. In this study, split-room boxes were used for culture of Cercis chinensis seedlings, and the small rooms were supplied with different nutrition levels. The number of the first-order roots in the rooms with nutrition supply was significantly higher than that in the rooms with deficient nutrition. Specific root length （SRL） of the first-order roots in the rooms with deficient nutrition reached its peak at day 64 after nutrition treatment. There was no significant SRL differences between the two order roots during the experiment. Biomass of the first-order roots in the rooms without nutrition supply was significantly less than that of the first-order roots in the rooms with nutrition supply from day 64 to 96. The total biomass of the lateral roots in the rooms without nutrition supply decreased from day 64 to 96. The activities of the enzymes in roots in the rooms without nutrition supply increased and the activities of alkaline invertases in roots in the two sides of split box did not change significantly. The activities of the enzymes in roots in the rooms without nutrition supply increased gradually. These results suggest that nutrition spatial heterogeneity induced the changes in root traits and plants actively controlled carbon usage in roots in nutrition-deficient patches by regulating the activities of invertases and sucrose synthases, resulting in the reduction in carbon usage in the roots in nutrition-deficient patches. 相似文献
16.
17.
18.
In natural ecosystems, nutrition available for plants shows great spatial heterogeneity. Much is known about plant root responses to the spatial heterogeneity of nutrition, but little is known about carbon usage in roots in nutrition-deficient patches and its effect on root longevity. In this study, split-room boxes were used for culture of Cercis chinensis seedlings, and the small rooms were supplied with different nutrition levels. The number of the first-order roots in the rooms with nutrition supply was significantly higher than that in the rooms with deficient nutrition. Specific root length (SRL) of the first-order roots in the rooms with deficient nutrition reached its peak at day 64 after nutrition treatment. There was no significant SRL differences between the two order roots during the experiment. Biomass of the first-order roots in the rooms without nutrition supply was significantly less than that of the first-order roots in the rooms with nutrition supply from day 64 to 96. The total biomass of the lateral roots in the rooms without nu-trition supply decreased from day 64 to 96. The activities of the enzymes in roots in the rooms without nutrition supply increased and the activities of alkaline invertases in roots in the two sides of split box did not change significantly. The activities of the enzymes in roots in the rooms without nutrition supply increased gradually. These results suggest that nutrition spatial heterogeneity induced the changes in root traits and plants actively controlled carbon usage in roots in nutrition-deficient patches by regulating the activities of invertases and sucrose synthases, resulting in the reduction in carbon usage in the roots in nutrition-deficient patches. 相似文献
19.
WANG Mingyu SHU Lifu WANG Jingsheng TIAN Xiaorui . Research Institute of Forest Ecology Environment Protection Chinese Academy of Forestry Beijing P.R. China . Tibet Agriculture Animal Husbandry College Linzhi P.R. China 《中国林业科技(英文版)》2005,4(4):49-53
With the influence of the world scope human being to the forest and climatic anomalies, forest fires in the world show the trend of escalation. US, Australia, Russia and Indonesia one after another had forest fires that were above 1 million hectares (ha). Impacted by the whole world forest fires situation, forest fires in China are very serious in the recent years. Forest fires in northeast and southwest China are unceasing, and the distribution of forest fires has the tendency to move south… 相似文献
20.
Calycophyllum spruceanum Benth. is an important tree for timber, charcoal and firewood in the Peruvian Amazon. The first provenance trial was established on farms in three zones located in one watershed in the Peruvian Amazon. The three zones differ in soil fertility and rainfall. Seven provenances from the Peruvian Amazon were tested in all three zones. Variation in four stem-growth traits (height, diameter, number of nodes and branches) and two branch-wood traits (basic density, heat content) was analyzed 18 months after establishment. There were significant differences in stem height and number of stem nodes among provenances in the analysis across zones. Provenance-related variation in stem-growth traits was most significant in the zone with the most fertile soils and highest rainfall. Branch-wood traits did not vary significantly among provenances in the analysis across zones or within zones. Branch-wood heat content was correlated with latitude, increasing from north to south, but this was only observed in a zone with low soil fertility and intermediate rainfall. Branch-wood density was correlated positively with stem diameter in the driest zone, but negatively with stem nodes in the intermediate zone and with stem height in the wettest zone. Results illustrate the potential for selection of fast-growing provenances, and the importance of replicating trials on different test environments to detect variation among provenances. 相似文献