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991.
论先秦时期我国的竹资源及利用   总被引:5,自引:2,他引:5  
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.  相似文献   
992.
毛竹林出笋与幼竹生长发育规律的研究   总被引:8,自引:1,他引:8  
本文以江苏宜兴林场、江西宜丰花桥林场以及南京林业大学下蜀实习林场等试验地内毛竹林出笋与幼竹生长资料和从江苏宜兴气象站抄录整理而成的1976~1986年中每年的11个气象资料为原始材料,定量地对毛竹林出笋及幼竹的生长发育的内在规律性及其与气象因子之间的关系进行了系统的研究。回归分析表明,影响翌年竹林出笋及幼竹生长发育的6个主导气象因子是7、8、9三个月的平均温度、年平均温度、年降水量、温暖指数、日均温≥10℃积温和7、8、9三个月的平均降水量。借助于有序样本聚类分析方法,将竹林整个出笋期划分为三个时期即出笋初期、出笋盛期和出笋末期。最佳拟合求算表明,毛竹幼竹高生长用单分子生长式来拟合精度较高。通过对正态累积函数和概率单位之间关系的研究可知,毛竹高生长在竹笋出土后21天左右进入速生期,竹笋出土后30天左右达高生长高峰期,竹笋出土后38天左右达高生长速生末期。本文还就如何根据幼竹的生长发育规律,采用相应的营林措施来培育速生丰产林等有关问题进行了探讨。  相似文献   
993.
木麻黄皮暗斑螟生物学特性的研究   总被引:4,自引:1,他引:4  
木麻黄皮暗斑螟(EuzopherabatangensisCaradja)在福建省一年发生5代,以幼虫于12月中旬在树干被害处的虫道内越冬(亦有少数以蛹越冬),林间世代重叠现象明显。成虫羽化盛期的温度为30.3—34.0℃,相对湿度为75.7%—84.3%,平均寿命7.9天,产卵量45.7粒。卵孵化率90.5%。幼虫共5龄,具群集性,以第一代幼虫取食量最大,老熟幼虫喜在粪粒层与树干交界部结茧化蛹,蛹期8.5天。皮暗斑螟的天敌有10余种,其中拟小腹茧蜂在自然界的寄生率达16%。  相似文献   
994.
Long-term observational data of the phenological network of the German Weather Service (DWD) were used to derive the altitudinal dependence of leaf unfolding (LU), leaf discolouration (LD) and the length of the vegetation period (LD-LU) of common beech (Fagus sylvatica L.) in different regions of Southern Germany. Depending on altitude, the vegetation period starts in Bavaria between the 2nd and 24th May with a delay of around 2 days per 100 m altitude increase (averaged over the last 30 years). In Southern Bavaria, LU starts a few days earlier as well as increases slightly faster into higher altitudes than in the northern regions. This can be explained by a more favourable supply of warmth and radiation in the south. The end of the vegetation period, defined here as the beginning of LD, showed no altitudinal dependence, which reflects an interaction of endogenous and exogenous factors as triggers for LD. In the Bavarian Forest region, altitudinal dependences are strongly influenced by sites which are affected by cold-air tailback (‘Kaltluftstau’) was obtained. Hence, phenological gradients should only be derived and applied above a phenological inversion zone. The calculated vertical gradients for LU can be used together with available observational data to estimate the beginning of the forest vegetation period of beech for different altitudes of Bavaria.  相似文献   
995.
The purpose of this study was to predict the likely amounts of carbon sequestration on a national scale for Japan in the Article-3.4 private planted forests of the Kyoto Protocol during the first commitment period. We regarded the planted forests that had undergone silvicultural practices such as weeding, pruning, and thinning since 1990 as Article-3.4 planted forests in accordance with the definition given by the Forestry Agency of Japan. Regression models were developed to predict the forest areas that had undergone silvicultural practices, employing silvicultural subsidies and forest workers' wages as predictor variables. Then the time series changes in the predictor variables were provided by extending their recent trends, with the result being that the forest areas that have undergone silvicultural practices were predicted on the basis of the three scenarios of the variables. Thus, the Article-3.4 forest area was calculated considering overlaps of silvicultural practices over fixed stands, and the area was converted into the amount of carbon sequestration by multiplying it by coefficients such as a volume table, biomass expansion factor, and others. The result implied that Article-3.4 private planted forests were expected to sequester 8.16–8.87 Mt-C year−1 during the first commitment period. These amounts cover 63%–68% of the carbon sequestration goal by land-use change and forestry activities capped under the Marrakesh Accords. To realize this prediction, it is important to provide a sufficient silvicultural subsidy to last until the end of the first commitment period and to implement silvicultural practices on the forest stands that have not undergone such practices since 1990.  相似文献   
996.
Adams  P.R.  Beadle  C.L.  Mendham  N.J.  Smethurst  P.J. 《New Forests》2003,26(2):147-165
Interference by an introduced grass, Holcus lanatus L. (Yorkshire fog grass) in a young E. globulus (Tasmanian blue gum) plantation was investigated. The objectives were to determine (1) the critical period of competition, and (2) how the timing and duration of competition was related to the interaction between tree growth and resource availability. This was investigated during the first two years of establishment. Weed interference was severe with height and diameter growth of weedy trees being 52% and 40% of weed-free trees, respectively, at age two years. Most growth losses occurred during the first year. The critical period of weed interference was from planting to age 18 m and effective weed control was required for this period to maximise tree growth potential. The application of nitrogen to weedy trees promoted a significant growth response suggesting that competition for nitrogen was occurring. There was no significant response to level of irrigation. The use of critical period analysis is discussed.  相似文献   
997.
《湖北林业科技》2015,(4):12-13
为探讨适宜保康县核桃苗木繁育方法,采用春季劈接和夏季留放水口露芽接、不留放水口露芽接、留放水口包芽接、不留放水口包芽接4种芽接方法进行嫁接,比较5种方法的成活率和出圃率,结果表明:在保康及附近区域,夏季采用芽接方法能有效地提高嫁接成活率和出圃率。  相似文献   
998.
从封山育林的理论基础和实践创新出发,阐述了上饶市林业建设的战略目标和经营措施.  相似文献   
999.
论封山育林的规划设计   总被引:1,自引:0,他引:1  
封山育林是培育森林资源的一条十分重要的途径,文中就封能林的范围,。封山育林规划设计中的空间配置,封育年限,育林措施等几个问题进行了探讨,提出了自己的观点。  相似文献   
1000.
我国封山育林研究进展*   总被引:8,自引:1,他引:8  
文中概述了封山育林的概念、技术措施以及封山育林的作用等方面的研究进展 ,并提出了封山育林今后研究的重点 ,主要是进行群落演替规律、生态恢复过程等封山育林的生态过程研究、封山育林生态功能及其提高技术研究、困难地带生态恢复与封山育林研究以及封山育林的生态系统管理研究。  相似文献   
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