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31.
Ophiostoma quercus (Ascomycota, Ophiostomatales) is a globally widespread, insect-vectored fungus that colonizes a wide diversity of hardwood and conifer hosts. Although the fungus is considered to be non-pathogenic, it is closely related to the fungi that cause Dutch elm disease. We examined the global diversity of O. quercus based on a ribosomal RNA marker and three unlinked gene regions. The fungus exhibited substantial morphological diversity. In addition, O. quercus had high genetic diversity in every continent from which it was collected, although the fungus was most diverse in Eurasia. There was no evidence of geographical clustering of haplotypes based on phylogenetic and network analyses. In addition, the phylogenetic trees generated based on the different markers were non-congruent. These results suggest that O. quercus has been repeatedly moved around the globe, because of trade in wood products, and that the fungal species most likely outcrosses regularly. The high genetic diversity of the fungus, as well as its ability to utilize a wide variety of arthropod vectors and colonize a tremendous diversity of tree host species makes O. quercus truly unique among ophiostomatoid fungi.  相似文献   
32.
Recent analyses of timber exploitation in Amazonia conclude that a variety of socioeconomic and ecological factors in the region make a stable and profitable logging industry virtually impossible. Most of these studies focus on large-scale timber industries and their dependence on over-exploitation of a small number of high-value timbers. In this article we discuss the economic, ecological, and social aspects of Amazonian logging in a region where the timber industry appeared to have collapsed after stocks of high-value timber were exhausted. We show that forestry in a post-boom phase, currently found in many areas of Amazonia, differs from the better-described boom period in its scale of operations, in the range of timbers cut, in management practices employed, and in the costs and benefits of production. Results of a seven-year study show that when sawtimber, poles and firewood are produced in a management system that combines forestry and agriculture they can provide significant additional income for Amazonian smallholders.  相似文献   
33.
报道了文山松毛虫质型多角体病毒杀虫剂的研制 ,包括多角体的纯化、辅助剂的筛选、剂型研制、产品包装以及病毒杀虫剂的产品质量检测及生产等。该杀虫剂为乳剂 ,多角体浓度达 2 .5×10 9PIB/mL ;所选辅助剂取材方便、容易配制 ,对环境没有污染。经安全检测证明 ,无致病菌 ,符合国家卫生标准 ,对试验动物小白鼠无毒性和致病性。生物测定用 1× 10 6PIB/mL感染 2龄文山松毛虫幼虫 ,其死亡率平均为 85 .5 %  相似文献   
34.
广东省林业有害生物的发生与防控   总被引:1,自引:0,他引:1       下载免费PDF全文
本文介绍了广东省林业有害生物的发生和防控概况,阐述了广东省以林业有害生物生态控制和绿色防控为导向,在立体化监测的基础上,建立树种合理配植避灾、检疫御灾、持续控制与应急控制相结合减灾的防控技术体系,以及林业有害生物防控技术规范化、标准化,防控工作社会化的保障体系,切实保护森林资源。  相似文献   
35.
广东林业生态省建设与红树林保护   总被引:5,自引:0,他引:5  
广东是我国红树林分布最多的省份之一,有红树植物17科31种,红树林湿地面积21 438.3hm2,主要分布在粤西,其次是珠江三角洲地区。红树林具有防灾减灾、净化环境、调节区域小气候、保护生物多样性等重要生态功能。在广东林业生态省建设中,保护和发展红树林被列为八大林业生态工程之一。本文对红树林的生态功能进行了具体分析;阐述了广东红树林资源分布现状、红树林在广东林业生态省建设中的作用以及保护、发展状况;指出目前红树林还面临围海造田、围海养殖、沿海城市化、废水污染等威胁,红树林保护任务艰巨;并就加强红树林保护提出建议。  相似文献   
36.
化感作用的研究意义及发展前景   总被引:119,自引:6,他引:113  
对化感作用在生态学、林业、农业等领域的理论及实践意义进行综述与探讨,并分析了其今后的发展方向.化感作用有助于更加合理地解释生态系统中植物组成与分布、群落演替、协同进化和生物入侵等现象;在林业生产的森林更新、混交林培育中有时会起到决定性作用;在农业上,单作、轮作、覆盖等各种种植方式均受化感影响,此外,一些化感物质可用作杀虫剂和除草剂,从而减轻对环境的污染水体中同样存在化感作用.培育新的抗虫害、抑草品种,分离、鉴定新的化感物质,深入揭示化感作用的机制,是今后化感作用的研究重点.  相似文献   
37.
Fire is a crucial element needed to understand the biodiversity patterns of forest landscapes in most Mediterranean countries. However, little is known about the quantitative responses of bird communities to postfire forest management in this region, in which the logging of burnt trees is a common practice. Several studies have already described the negative effects of felling burnt trees on birds but none has focussed on the remaining wood remnants. We investigated this question in a large burnt area located in north-east Iberian Peninsula. The amount of logging remnants left on the ground had positive linear and negative quadratic relationships with the indices of bird abundance and bird richness. The results obtained at a species level were similar, since 36% of the most abundant species revealed the same type of relations with logging remnants, whereas none showed an opposite pattern. Thus, birds in general seem to be positively influenced by the amount of wood remnants left on the ground to a certain point, from which the relation reverses. The results of this study indicate that a moderate amount of wood remnants left on the ground may be positive for the overall bird community. We suggest that management plays a role in the recovery of the bird community after fire and, therefore, biodiversity criteria should be incorporated in the guidelines driving postfire actions.  相似文献   
38.
We assessed species richness and distribution of the apoidean fauna of the coastal Maulino forest, an endemic and threatened forest in central Chile. Remnant forest fragments are immersed in commercial pine plantations, who act as the habitat matrix. The bee assemblages depict a non-nested structure at the landscape level at times when pine plantations are standing. However, assemblages are nested in the fauna of forest fragments at times when plantations are harvested, suggesting that plantations might be acting as habitat providing connectivity between remnants of Maulino forest. Therefore, the conservation of apoideans might require a landscape level approach to be successful, including partial reliance on plantations.  相似文献   
39.
制革污泥林业利用场水域的鳑鮍鱼外周血红细胞微核监测   总被引:1,自引:0,他引:1  
制革污泥施入林地后,检测小流域地表水、土壤渗出水对鱼(Rhodeussinensis)外周血红细胞微核的诱变。结果表明:在实验范围内,没有诱发鱼血红细胞微核率增高,制革污泥林业利用系统是安全的;但鲜制革污泥浸出水可诱发鱼外周血红细胞微核率增高,故制革污泥如不加任何处理而随意堆放,会对坏境造成污染。  相似文献   
40.
基于对辽宁省主要农业自然灾害发生与为害的分析和对林业生态工程建设科学积累的归纳总结,论证了防御农业自然灾害的对策——林业生态工程建设,具有防御多种自然灾害、发挥多种效益的功能和持久、稳定而易于建设的特点。以此为基础,根据主要农业自然灾害在辽宁省各地区的分布特点,在宏观上提出了辽宁省防御主要农业自然灾害的林业生态工程建设框架:在已有林业生态工程建设的基础上,继续开展以水土保持林为主的辽西林业生态工程建设,加强以农田防护林为主的辽中和辽北林业生态工程建设,大力开展以海防林为主的沿海地区林业生态工程建设,实施科学的辽东山区多样化森林经营方式,并以科技兴林保证林业生态工程建设这一总体布局的实施。同时简述了各项林业生态工程的具体实施方法。  相似文献   
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