共查询到20条相似文献，搜索用时 515 毫秒
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1 湿地资源概况黄河三角洲是我国的三大三角洲之一 ,是继长江三角洲、珠江三角洲开发之后待开发的重要区域。由于黄河携带大量泥沙填海造陆 ,黄河三角洲形成了大面积宝贵的原生湿地 ,总面积约 45 0 0ｋｍ2 ,其中2 0 0 0ｋｍ2 的潮上带湿地 ,10 0 0Ｋｍ2 潮间带湿地和15 0 0ｋｍ2 的潮下带湿地。 1992年 10月经国务院批准 ,在原生湿地最具代表性的区域设立了 15 30ｋｍ2 的自然保护区。黄河三角洲自然保护区是以保护黄河口新生湿地生态系统和珍稀濒危鸟类为主体的湿地类型保护区。经国内外著名专家认证 ,该保护区是中国暖湿带保存最完整、最… 相似文献
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黄河三角洲自然保护区植被调查报告 总被引：9，自引：0，他引：9
黄河三角洲自然保护区植被调查报告赵延茂，吕卷章（山东黄河三角洲国家级自然保护区管理局）马克斌（东营市林业局）山东黄河三角洲国家级自然保护区（以下简称保护区）是一个新生的湿地生态系统。作为这一湿地生态系统基本而重要组成部分的植物资源，不仅可为鸟类提供食... 相似文献
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湿地是重要的生态系统,其特殊的地位和作用受到越来越多的关注,建立湿地生态补偿制度将成为保护湿地的长效机制.本文以山东黄河三角洲国家级自然保护区为研究对象,概述了保护区基本情况和目前存在的主要问题,即工农业生产活动频繁,湿地退化严重,可持续发展能力较弱,保护管理水平有待提高.阐述了建立湿地生态补偿机制对保护湿地,持续利用湿地资源,充分实现公共资源的生态服务价值,达到可持续发展的必要性;并针对山东黄河三角洲国家级自然保护区的实际情况,提出建立相关法规条例,创建适合本地区的湿地生态补偿机制;同时强调加强监督管理和宣教工作,促进公众参与. 相似文献
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刘月良 《绿色中国(综合版)》2013,(20):36-41
黄河三角洲湿地是中国暖温带保存最完整、最广阔、最年轻的湿地生态系统,是东亚至澳大利亚、东北亚内陆和环西太平洋鸟类迁徙的重要中转站、越冬地和繁殖地。为了加强黄河三角洲湿地的保护,东营市人民政府于1990年12月批准建立黄河三角洲市级自然保护区;1991年11月被山东省政府批准为省级自然保护区;1992年10月被国务院批准为国家级自然保护区。 相似文献
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刘月良 《绿色中国(A版)》2013,(10)
黄河三角洲湿地是中国暖温带保存最完整、最广阔、最年轻的湿地生态系统,是东亚至澳大利亚、东北亚内陆和环西太平洋鸟类迁徙的重要中转站、越冬地和繁殖地。为了加强黄河三角洲湿地的保护,东营市人民政府于1990年12月批准建立黄河三角洲市级自然保护区;1991年11月被山东省政府批准为省级自然保护区;1992年10月被国务院批准为国家级自然保护区。山东黄河三角洲国家级自然保护区位于山东省东营市境内的黄河入海口处,是以保护黄河口新生湿地生态系统和珍稀濒危鸟类为主体的湿地类型自然保护区,总面积15.3万公顷,其中核心区5.94万公顷,缓冲区1.12万公顷,实验区8.24万公顷。其区域分两部分：南部区域位于现行黄河入海口,面积10.45万公顷;北部区域位于1976年改道后的黄河故道入海口,面积4.85万公顷。 相似文献
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黄河三角洲自然保护区原生湿地生态系统演化规律研究 总被引：5，自引：0，他引：5
黄河三角洲自然保护区是以保护黄河口新生湿地生态系统和珍稀濒危鸟类为主体的国家级自然保护区,自1992年10月经国务院批准建立以来,保护区加大科研力度,实行依法治区,加强湿地生态系统的恢复和重建,使这片新生湿地得到了有效保护,保护了这片新生湿地生态系统的典型性、完整性和科学性。但由于多年来油田在自然保护区实验区及毗邻区的开发,保护区的生态环境面临一定的负面影响,如不采取措施,长此下去,将会产生一系列生态和环境问题,使区域脆弱的生态环境更加脆弱。为了保护好这块国际重要湿地,多年来,我们加强了自然保护区生态环境演化监测… 相似文献
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通过对广德县湿地资源的调查、摸底、了解和分析,基本掌握了广德县湿地的生态环境、湿地资源类型、面积及自然分区,阐述了广德湿地自然保护区、湿地公园发展历程、发展现状、经验和问题,在分析广德县湿地资源及保护管理基本概况的基础上,对广德县湿地资源如何进一步加强保护管理拟定了短期、中期和长期目标,展望了广德县湿地资源保护和管理的美好前景,同时也为加大对广德县湿地资源保护和管理的力度,奠定和夯实了理论基础. 相似文献
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泉州湾湿地生态旅游资源保护与开发刍议 总被引：8，自引：1，他引：8
泉州湾湿地是我国东南沿海典型湿地类型之一,其特殊的地理、自然条件和人类长期活动形成独特的湿地旅游资源,湿地多样性明显,但也伴随人为强度干预导致的景观脆弱性。为此,本文提出泉州湾湿地的保护和开发思路:①进行泉州湾湿地资源的本底调查,申报国家级湿地自然保护区;②制定湿地生态旅游发展规划,并逐步建立和完善生态旅游服务网络体系;③政府决策与社区参与相结合;④加强湿地旅游管理和环境影响评价。总之,泉州湾湿地旅游开发必须定位在生态旅游资源的保护开发,改变以往只重视其生产功能而忽视其生态、社会、文化功能的倾向,实现湿地资源的可持续利用。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
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Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and
also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the
amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter
bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K
was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed
significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week−1 for leaves and from 0.0225 to 0.0633 week−1 for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed
during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly
between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species
provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient
enrichment capacity and slower decomposition rates which would minimize leaching losses.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
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本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):118-130
The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions. 相似文献
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Astra Zaluma Lauma Bruna Darta Klavina Natalija Burnevica Kristine Kenigsvalde Andis Lazdins Talis Gaitnieks 《Forest Pathology》2019,49(6)
Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered. 相似文献
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Steven Maranz Amadou Niang Antoine Kalinganire Djeneba Konaté Bocary Kaya 《Agroforestry Systems》2008,72(3):231-239
Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional
data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral
contents and B1 and B2 vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising
germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B1 88 mg 100 g−1, B2 187 mg 100 g−1, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal
diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties
to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations. 相似文献
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《Wood material science & engineering》2013,8(2):76-84
Abstract Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists. 相似文献