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101.
云南野生动物肇事危害情况及对策探讨   总被引:2,自引:0,他引:2  
云南被誉为"动物王国",自然条件优越,适于各种野生动物生息繁衍。随着保护力度的加大,其野生动物的数量猛增,与人的冲突日显突出,肇事危害频繁,损失严重。针对云南野生动物肇事危害的原因和特点,提出多渠道、综合治理的对策建议。  相似文献   
102.
萧氏松茎象的生活史和生态影响因子研究   总被引:3,自引:0,他引:3  
萧氏松茎象在湖南省主要危害湿地松和马尾松。通过采用解剖林内虫害木的研究方法和林间的定期观察技术,对萧氏松茎象在湖南的生活习性及主要的生态影响因子进行了研究,研究结果表明萧氏松茎象在湖南的郴州两年发生一代,寄主种类、林分类型和林内植被直接影响萧氏松茎象的发生危害程度。  相似文献   
103.
2007年6月,作者在甘肃尕海—则岔自然保护区发现一个黑冠山雀Parus rubidiventris的洞穴巢址并对繁殖行为作了记录。巢址位于云杉树基下,大小27 cm×11 cm、巢深17 cm。巢材由苔藓、草茎须根、羊毛、云杉叶等组成。黑冠山雀育雏频率1次/1.5 min,食物为膜翅目、鳞翅目昆虫。此外,还发现育雏结束后亲鸟有清除巢内异物行为。  相似文献   
104.
Lifting for handling and flatbed truck transportation to the job site are important processes during manufacture of prefabri-cated wooden construction units like mini homes and building modules. Significant damage can occur to sections or components of units during these operations. Although damage usually will not impair its structural safety, it is costly to fix and causes the public to perceive prefabricated wooden buildings as low quality products. Field observations and preliminary numerical models for prefabri-cated units subject to lifting and transportation forces are summarized here. Once fully developed and verified, models will support the creation of damage mitigation strategies centered on structural details indicating how units are to be supported during lifting and transportation.  相似文献   
105.
A hailstorm in October 1994 was found to have moderately or severely impacted on 5.3% of the mangrove forests in Port Curtis. All mangrove species showed evidence of hail damage, including the three most common species (Rhizophora stylosa, Ceriops tagal and Avicennia marina). Physical effects of hail damage included stripping of leaves from plants, holes punched through leaves, bruising to bark, divots removed from bark, branch and plant death. Speciesspecific differences in vulnerability to the effects of hail were observed with C.tagal experiencing relatively higher mortality rates than the other two common mangrove species. A delayed pattern of mortality was observed in two species _ C.tagal and A.marina. Alterations to mangrove community structure included: (1) reductions in stem density, stem diameter and basal area, (2) reductions in canopy cover (based on a photographic index of foliage projective cover) and (3) changes in relative abundance of species in mangrove zones. Recovery was observed in some stands but others had not recovered to prehail levels of canopy cover two years after the hailstorm. Recovery had occurred by regeneration of fresh leaves but no recruitment of young plants had been observed during the study. The forests in the impact area were dominated by either Ceriops tagal or Rhizophora stylosa with Avicennia marinaas a subdominant in places. C.tagal dominated forests within the impact area were relatively more severely affected (41.8% in the severe category) than R.stylosa dominated communities (only 17.4% in the severe category). This indicated that C.tagal dominated forests were more vulnerable to the effects of hail damage than R.stylosa dominated forests. In addition, hailimpacted C.tagal dominated forests represented a relatively high percentage of the area of C.tagal dominated forests in Port Curtis (44.3%). This percentage was much higher than hailimpacted R.stylosa dominated forests in Port Curtis (2.7%). These two factors – relatively severe impact on C.tagal communities and a relatively higher percentage affected within the Port Curtis area – illustrate that hailstorms, as a form of natural disturbance, are an important influence on the forest ecology of mangrove ecosystems in this region.  相似文献   
106.
The growing condition of afforestation trees and damage to lower-story trees caused by felling and hauling of upper-story trees in a multi-storied forest in Peninsular Malaysia was surveyed. Seventy months have passed since the planting ofAcacia mangium upperstory trees, which have grown 233 m3/ha in volume. The growth ofShorea leprosula thirty-five months after planting of lower-story trees have reached 5.54 m in height. However, as the ratio of height to basal diameter exceeds 100:1, trees are tapering to a considerable degree. A backhoe was installed in order to fell the upper-story trees. From the results of logging, the damage ratio estimation of the lower-story trees was simulated by using the Monte Carlo method. The damage ratio differed considerably depending on planting patterns, height of upper-story trees and felling skills. The results of this survey proved that the felling and hauling of upper-story trees would be technically feasible in the future, except when one row upper-story trees and one row lower-story trees method were employed.  相似文献   
107.
以位于粤北山区天井山林场的杉木(Cunninghamia lanceolata)人工林中的受损杉木为研究对象,研究了2008年初冰雪灾害后1年内受损杉木的恢复和更新情况。采用标准地调查法,选取4种不同类型受损杉木的标准木(类型Ⅰ:断干高在原树高的1/3内;类型Ⅱ:断干高在原树高的1/3~2/3处;类型Ⅲ:断干高在原树高的2/3以上;类型Ⅳ:倒伏),监测其自2008年11月—2009年11月期间的萌条高和基径的月生长动态。结果表明:冰雪灾害后的一年内,受损杉木萌条高生长的旺盛期为5—9月份,而基径生长总体呈现初期生长增加明显,后期增速逐渐缓慢的特点。林分密度与受损杉木萌条的生长关系密切,需在灾后杉木人工林重建时给予重点关注。受损Ⅲ型和受损Ⅳ型杉木萌条生长较好,但综合考虑生长和成材效果,建议保留受损Ⅲ型,伐掉受损杉木Ⅰ型、Ⅱ型和Ⅳ型。  相似文献   
108.
纵坑切梢小蠹对加勒比松的为害   总被引:2,自引:0,他引:2  
对纵坑切梢小蠹在白云山不同变种加勒比松的为害状况进行了初步调查,掌握了该虫为害松树的特征如:侵入孔部位、侵入孔直径、侵入孔道长度、为害梢直径、为害梢长度等,发现纵坑切梢小蠹对疏叶型本种加勒比松的春梢为害较严重。  相似文献   
109.
松材线虫病研究进展   总被引:10,自引:0,他引:10  
概述了松材线虫的生物学特性、行为学、致病机理等方面的研究动态,并介绍了松材线虫病环境影响评价的研究进展,提出了目前对松材线虫病的环境影响经济评价尚属空白,在松材线虫病对环境影响方面缺乏深入的研究。对其致病主要机理仍不清楚,需进一步进行研究。  相似文献   
110.
郭垂根  王清文 《林业研究》2007,18(3):203-207
MA-SEBS as compatibilizer and impact modifier was incorporated into Polypropylene/Wood Fiber (PP/WF) to enhance interface adhesion and impact strength of the composite. The effect of MA-SEBS content on the impact fracture behavior of PP/WF composites was studied. The impact properties of composites with 8% MA-SEBS reached the maximum value. And further increasing of MA-SEBS content to 10% did not improve the fracture toughness, but improved the stiffness of composites by DMA analysis. This was attributed to the improved PP/WF adhesion. As the MA-SEBS content is more than 8%, the molecule interaction of PP and WF was expected to much stronger than lower MA-SEBS. Scanning electron microscopy (SEM) was performed to analyze the impact fracture surface and showed a stronger affinity for the wood surfaces.  相似文献   
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