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1.
阐述了近年来国内外对蕨类植物以及猴腿蹄盖蕨繁育方式的研究状况,为蕨类植物及猴腿蹄盖蕨的研究提供了借鉴资料,并对猴腿蹄盖蕨组培快繁技术的研究做了较详细介绍。  相似文献   

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为提高液化效率,以水为介质,将麦秆纤维在不同的微波条件下进行预处理,研究微波处理对液化效率的影响,利用FT-IR、SEM、XRD等仪器分析方法对微波处理前后的麦秆化学结构、纤维形貌和聚集态结构等进行对比分析,研究了微波加速液化反应的机理。结果表明:其他条件相同时,微波预处理3 min可将液化反应时间由未处理时的60 min降低至处理后的40 min,效果明显;研究发现微波预处理不会改变液化反应的历程,但适当的微波作用使麦秆纤维的结晶度由未处理前的46.35%下降到30.7%,麦秆纤维表面变得疏松,可及度变大,因此反应活性增强。  相似文献   

4.
采用不同光照、不同温度预处理板栗离体叶片,测定其总酚含量和多酚氧化酶活性的动态变化。结果表明:采用自然光照、12h光照和25℃温度处理能明显降低板栗叶片中总酚含量和多酚氧化酶活性,并都在处理后的第2天降到最低值。  相似文献   

5.
不同采伐方式对阔叶林物种多样性的影响研究   总被引:1,自引:0,他引:1  
对阔叶林皆伐人促更新和择伐人促更新对物种多样性影响的研究,结果表明不同采伐方式对群落物种丰富度、物种多样性指数和物种多样性均匀度指数均有一定的影响.皆伐人促更新林分物种比择伐人促更新少10种,乔木树种少了14种;不同采伐方式对群落的物种多样性指数和物种多样性均匀度指数影响不大,但对各层片有较大的影响,皆伐人促更新的乔木层物种多样性指数和物种多样性均匀度指数均比择伐人促更新林分低,但草本和藤本层物种多样性指数和物种多样性均匀度指数均比择伐人促更新林分高.  相似文献   

6.
The purpose of this study was to determine a suitable model for investigating the effects of climate factors on the area burned by forest fire in the Tahe forest region, Daxing’an Mountains, in northea...  相似文献   

7.
  • ? The effect of nitrogen (N) deposition on the decomposition of pine (Pinus massoniana) needles in a tropical pine plantation was studied. The pine needles with two different nutrient status (nutrient-rich and nutrient-poor) were used, followed by 3-levels of N treatments (Control: no N addition, Low- N: 5 g N m?2 y?1, and Medium-N: 10 g N m?2 y?1 experimental inputs), which had been applied for 26 months continuously before this experiment and continued throughout the decomposition measurement.
  • ? The main objective was to test the hypothesis that decomposition of nutrient-rich needles would be more sensitive to cumulative N deposition than the decomposition of nutrient-poor needles.
  • ? Nitrogen addition had negative effect on mass loss, and the release of N and P from decomposing nutrient-rich needles but little or no effect on the decomposition of nutrient-poor needles. In addition, a negative effect in the initial decomposition phase and a positive effect in later decay stages were found on C release. The negative effect was stronger on nutrient-rich needles than on nutrient-poor needles, but the reverse was true for the positive effect.
  • ? Our results suggest that response of litter decomposition to N deposition may vary depending on the nutrient status of the litter.
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    8.
    Korean larch(Larix olgensis) is one of the main tree species for afforestation and timber production in northeast China. However, its timber quality and growth ability are largely infl uenced by crown size, structure and shape. The majority of crown models are static models based on tree size and stand characteristics from temporary sample plots, but crown dynamic models has seldom been constructed. Therefore, this study aimed to develop height to crown base( HCB) and crown length( CL) dynamic models using the branch mortality technique for a Korean larch plantation. The nonlinear mixed-effects model with random effects, variance functions and correlation structures, was used to build HCB and CL dynamic models. The data were obtained from 95 sample trees of 19 plots in Meng JiaGang forest farm in Northeast China. The results showed that HCB progressively increases as tree age, tree height growth(HT growth) and diameter at breast height growth( DBH growth).The CL was increased with tree age in 20 years ago, and subsequently stabilized. HT growth, DBH growth stand basal area( BAS) and crown competition factor( CCF) signifi cantly infl uenced HCB and CL. The HCB was positively correlated with BAS, HT growth and D BH growth, but negatively correlated with CCF. The CL was positively correlated with BAS and CCF, but negatively correlated with D BH growth. Model fi tting and validation confi rmed that the mixed-effects model considering the stand and tree level random effects was accurate and reliable for predicting the HCB and CL dynamics. However, the models involving adding variance functions and time series correlation structure could not completely remove heterogeneity and autocorrelation, and the fi tting precision of the models was reduced. Therefore, from the point of view of application, we should take care to avoid setting up over-complex models. The HCB and CL dynamic models in our study may also be incorporated into stand growth and yield model systems in China.  相似文献   

    9.
    为了掌握近年来我国对林业有害植物研究的现状和动态,客观反映相关机构、科研院所和高等院校在该领域的研究内容和关注力度,通过中国知网平台对2003年1月至2015年1月期间的中国林业有害植物研究相关文献进行搜集,使用文献计量法对相关文献的发表刊物、发表年份、研究机构和涉及学科等情况进行统计分析,结果显示,林业有害植物研究文献发文量排前的23种期刊里,文献主要集中在8种(占60%以上)期刊中;发文数量整体上呈逐年递增趋势,伴有小幅波动,这可能与定期林业有害生物普查有关;发文最多的单位是国家林业局森林病虫害防治总站和国家林业局,共42篇(占38.53%),说明国家层面较为重视;对林业有害植物研究涉及最多的7个学科方向进行了分析,其中关于林业有害植物生物学和生态学与国外相比,研究相对较少。  相似文献   

    10.
    The present paper deals with laboratory studies on side-effects of the mixed biocide GCSC-BtA on Plutella xylostella (L.) (Lep., Plutellidae) and its predators, e.?g. Amblyseius longispinosus (Evans) (Acari, Phytoseiidae), Erigonidium graminicola (Sundvall) (Araneae, Linyphiidae), Orius similis Zheng (Het., Anthocoridae) and Coccinella septempunctata L.(Col., Coccinellidae), in comparison to the commercial insecticides, e.?g. Abamectin, Tebufenozide, Dichlorvos, Cartap and Lambda-cyhalothrin. The results showed that GCSC-BtA was highly toxic to the 3rd instar of P. xylostella with 91.18?% mortality, followed by Cartap with 84.38?%, Abamectin with 78.00?%, Tebufenozide with 75.57?%, Lambda-cyhalothrin with 63.75?% and Dichlorvos with 50.86?% mortality. On the other hand, GCSC-BtA was found to be comparatively less toxic to the predators, causing 31.11?%, 13.33?%, 11.54?% and 6.00?% mortalities in A. longispinosus, E. graminicola, O. similis and C. septempunctata, respectively. For comparison, the mortalities recorded for Abamectin, Tebufenozide, Dichlorvos, Cartap, Lambda-cyhalothrin were 72.94?%, 55.55?%, 70.00?%, 53.26?% and 98.85?% in A. longispinosus, 46.51?%, 55.10?%, 60.00?%, 46.00?% and 73.68?% in E. graminicola, 22.00?%, 16.00?%, 35.71?%, 26.78?% and 81.03?% in O. similis, 15.55?%, 19.64?%, 28.00?%, 16.66?% and 41.79?% in C. septempunctata, respectively. Cluster analysis was introduced to group the mortalities caused by the treatments into three toxicity groups with the distance of D?=?4.1. The 1st group consisted of GCSC-BtA characterized with low toxicity to all the predators tested with 15.49?% mortality on average (highest 31.11?% and lowest 6.00?%). The 2nd group consisted of Abamectin, Tebufenozide, Dichlorvos and Cartap with moderate toxicity to the predators with 39.96?% mortality on average. The 3rd group included Lambda-cyhalothrin with high toxicity to the predators with 73.83?% mortality on average (highest 98.85?% and lowest 41.70?%). The susceptibility of the pest and its predators to GCSC-BtA and the insecticides is discussed. GCSC-BtA as a biological control agent is recommended for use in the integrated pests control programs in the vegetable fields.  相似文献   

    11.
    在当今世界人类面临的诸多问题中,土地荒漠化已成为最为严重的环境与社会经济问题,被称为地球的癌症。据联合国公布的数字,不当的人类活动以及气候变化导致占全球41%的干旱地区土地不断退化,荒漠面积逐渐  相似文献   

    12.
    奉新县毛竹产业发展对策初探   总被引:1,自引:0,他引:1  
    奉新县是中国竹子之乡,具有发展竹产业的天然优势。但同时也存在技术创新能力不足、资源日益紧缺且浪费严重、企业无序竞争突出、毛竹产区基础设施落后等制约奉新县竹产业发展的问题;能否抓住消费者普遍重视产品环保性能的机遇,加强毛竹资源培育、优化工业产品结构,扩大附加值更高的重竹制品、生化加工品的比重,并从政策、资金等方面给予毛竹培育和加工企业必要的扶持,成为了奉新毛竹产业转型升级的关键因素。  相似文献   

    13.
    何方 《经济林研究》2002,20(4):23-26
    生态区评价是国际上新近发展起来的一种科学方法和实践。有利解决资源开发利用保护生态环境的矛盾。中国生态区划分以地面景观为标准,并建立二级分类系统,区一亚区,同时充分利用政府行为。将全国共划分为10个一级生态区;天然林保护生态区、自然保护区生态区、水土保持生态区、防护林生态区、荒漠生态区、湿地生态区、林业生态区、草原生态区、农业生态区、青藏高原高寒生态区。  相似文献   

    14.
    何方 《经济林研究》2003,21(3):24-27
    生态区评价是国际上新近发展起来的一种科学方法和实践。有利解决资源开发利用保护生态环境的矛盾。中国生态区划分以地面景观为标准,并建立二级分类系统,区一亚区.同时充分利用政府行为。将全国共划分为l0个一级生态区:天然林保护生态区、自然保护区生态区、水土保持生态区、防护林生态区、荒漠生态区、湿地生态区、林业生态区、草原生态区、农业生态区、青藏高原高寒生态区。  相似文献   

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