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在遥感、地理信息系统的支持下,基于2003、2011年Landsat-7卫星影像数据,运用Fragstats3.3景观格局分析软件和景观生态学的基本原理、方法,通过对比2003、2011年景观格局指数,分析研究福建省平潭岛的景观格局时空演变规律。结果表明:研究区景观各要素特征发生了较大变化,城镇、农村居民点的斑块面积由2003年的2464.08 hm2增加到2011年的4550.83 hm2;景观空间结构的变化表现为景观类型的形状指数和分维数都有不同程度的增加;邻近景观指标总体呈下降趋势,表明景观类型之间距离更远,变得更离散;景观异质性指数中的廊道斑块密度明显增大,增加量为21.96个.hm-2。8 a间平潭岛的景观格局呈现剧烈变化态势。 相似文献
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以福建晋江沿海防护林的5种主要类型为研究对象,从景观生态学的角度,运用RS和G IS技术,对1989年,1993年,2001年,2008年4个时相的遥感影像进行解译,结合实地调查,得到晋江市4个时相防护林的景观格局图。应用景观分析软件Fragstats,分别计算其景观格局指数并进行分析。结果表明:1989—1993年,5类防护林面积均明显减小,斑块密度增加,破碎化程度加大;1993—2001年,破碎化程度进一步加剧,而以农田防护林网最为明显;2001—2008年,防护林景观格局整体好转,但海岸基于林带仍呈下降趋势。说明基干林带一旦遭受破坏则很难恢复,应加强基干林带保护和建设。 相似文献
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《林业调查规划》2021,46(3)
选取文峪河流域为研究对象,利用GIS等软件综合自然、社会评价因子,从多个角度构建流域景观安全格局,分析流域景观安全格局的结构特征、转移动态、空间分布以及景观安全指数与人口密度、经济总量、生态系统服务的相关性;利用Linkage Mapper软件分析景观源与生态廊道的重要性,从多角度、多因子构建流域健康度评价体系,并分析流域健康格局的结构特征、转移动态、梯度分布、驱动机制,以及健康指数与人口密度、经济总量、生态系统服务的相关关系。研究结果表明,文峪河流域景观安全格局结构特征及转移动态变化复杂,流域景观安全格局结构整体向好,景观安全指数与经济总量、人口密度、生态系统服务之间存在密切的相关关系,不同景观源与生态廊道的生态重要性不同,提出"一带三区三轴多点"的生态框架对景观格局进行优化;文峪河流域健康格局结构特征及转移动态变化复杂,流域健康格局结构向好,城区与林区的健康度梯度不同,健康指数与经济总量、人口密度、生态系统服务之间存在密切的相关关系,不同驱动因子对健康度的驱动作用不同。流域景观安全区面积与景观健康区面积的增加已趋于饱和,应加强对流域的研究与保护,促进流域的可持续发展。 相似文献
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以河北省大清河水系阜平流域为研究对象,利用景观格局指数分析法、服务功能价值量评价法及相关分析等方法,研究了1985—2015年该区域土地利用景观格局及生态系统服务价值变化规律,分析了服务功能与土地利用景观格局之间的相互关系,探讨了生态服务功能对土地利用景观格局变化的响应过程。结果表明:1)研究区近30年城市、林业、农业、水域景观呈增加趋势,荒漠、草地景观呈减少趋势。总体上表现为斑块数量减少,平均斑块面积增大,各景观类型连通性增强,景观结构愈加稳定。2)研究区生态服务总价值在2000年最高(58.08亿元),2000年之前呈增加趋势,2000年之后呈减少趋势。林地服务价值贡献率最大,其次为农田和草地;单项服务价值中维持生物多样性与保持土壤服务贡献率最大,其次为气体调节和气候调节。3)生态系统总服务价值与斑块密度、景观形状指数、面积加权平均形状指标、面积加权平均分维数、平均斑块面积、聚集度均有较强的相关性。 相似文献
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《河北林果研究》2020,(3)
为研究郑汴地区湿地景观变化,以遥感和GIS为技术依托,采用1992年、2002年、2013年3期Landsat影像数据结合郑汴地区湿地景观的区域特征,通过景观蔓延度指数、景观形状指数、香浓多样性指数、斑块连接度指数等空间格局指数的分析,系统研究了郑汴地区湿地景观的演变。结果表明:1992-2013年的近二十年间,郑汴地区河渠景观、滩地景观和库塘景观三大湿地景观面积总体上呈现出减小趋势,且减小幅度较大。景观格局动态变化表现为景观香浓多样性指数有小幅度增大。从景观形状指数上看,河渠景观和库塘景观下降,滩地景观略有上升,总体来看研究区景观形状指数呈上升趋势,景观几何形状趋向规则。蔓延度指数较小,景观呈多要素密集格局。自然变化特别是人类干扰对于郑汴地区湿地景观变化有重大影响。 相似文献
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以黄河三角洲地区东营市部分为研究区域,研究了黄河三角洲河道演变规律与景观格局分布规律,并着重研究了该地区河道演变与景观格局分布的联系。结果表明:近20年间黄河总取水量呈上升趋势;2002~2010年裸地沼泽面积明显减少,植被面积增多。2010~2019年,建设用地面积明显增加;土地利用景观格局的形式从沿海区域开始向内陆演变呈现一定的规律,最外环为海洋、向内依次为是浅海滩涂、滩涂、水产湿地、盐田、旱地、沼泽湿地、植被、建设用地;受季节影响较大的图可以利用ENVI提取其对应的植被覆盖图来消除影响。在NDVI植被归一化指数的基础之上建立植被覆盖图,通过NDVI指数分析植被的长势和营养状况。 相似文献
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基于GIS 技术,以怒江流域中段典型地区(福贡县)为研究区域,利用1986 年、1994 年和2004年TM卫星遥感影像,分析了3个时期的景观格局特征及其变化.结果表明,怒江流域中段典型地区(福贡县)整体景观以有林地为基质,灌木林以及其它景观类型镶嵌于其中.有林地的面积1986～2004年呈持续减少趋势;灌木林、荒草地、耕地、滩涂和城镇则是持续增加.斑块数持续增加,景观破碎化趋势明显;景观多样性指数增加、优势度指数减小,景观趋于多样化和均匀化;斑块被分割严重,景观总体连通性下降.人为干扰是导致该区景观格局发生变化的主要驱动因子. 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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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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《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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《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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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