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1.
The aim of this study was to determine the possible effects of meteorological factors on the crown condition of Norway spruce in habitats with different site humidity. In many cases the correlation between meteorological indices and crown condition was stronger and more reliable in habitats with normal humidity than in overmoist habitats. Our results suggest that meteorological conditions during the vegetation period play more significant role compared with dormant period for spruce crown condition.  相似文献   

2.
Trends in stem temperature of Scots pine trees in different life states are described. Any substantial disturbances of water flow in the roots, stem, or crown have an immediate effect on the stem temperature. This temperature shows a strong inverse correlation with the state of the tree, with the coefficient of determination ranging from 0.710 to 0.974. The method of assessing the physiological state of trees by temperature parameters allows early diagnosis of decline in the viability of conifers.  相似文献   

3.
Taxonometric parameters and morphological characters of cones and seeds were studied in larch trees growing in uneven-aged larch forests of the green-moss and herbaceous types. Significant differences in trunk volume and the number of cones in the crown was revealed. Differences in the parameters of cones and the quality of seeds proved to be insignificant. Correlations between the taxonometric parameters of trees and the morphological characters of cones and seeds were analyzed.  相似文献   

4.
The structure of the crown and branching; the growth, development, and ontogeny of branches; and organogenesis and growth of female shoots in the model Siberian stone pine trees were studied in four types of habitats at the timberline in the central Altai Mountains (1700–2170 m a.s.l.). The results provided evidence that the ecological forms of trees appear due to changes in the pattern of branching as well as to the decreased rate of vegetative (primarily apical) growth. The diameter of the shoot pith is one of the most variable characters reflecting the deterioration of environmental conditions at higher elevations.  相似文献   

5.
The ideas concerning the spatial and temporal variation of acidity and composition of atmospheric fallout in forests of the boreal zone are discussed. The role played by the atmospheric component in the functioning of these forests depends on the acidity and composition of fallout and the extent of their transformation by the biocenosis. The most profound transformation of fallout occurs during the growing season. In spaces between crowns, the corresponding changes are atmogenic; in undercrown areas, they are obviously biogenic (autogenic). Spruce transforms the fallout more intensively than pine. Under conditions of industrial pollution, the atmobiogenic character of fallout is supplemented with a technogenic component, as its acidity and concentration of pollutants and other elements sharply increase. Concentrations of principal cations reach high values because of their leaching from the crown by acid precipitation. The traditional concept of atmospheric load on boreal forests should be reconsidered taking into account their spatial structure.  相似文献   

6.
To understand the effects of different disturbance regimes on the bud bank demography in perennial grasslands, we conducted a demographic field investigation of the bud bank in a typical steppe on the Loess Plateau. Grazing significantly decreased and fire significantly increased bud bank density compared to fenced grasslands. For different bud bank types, grazing significantly decreased tiller bud bank density, and fire significantly increased the density of root crown buds and rhizomatous buds in relation to fenced grasslands. Tiller buds accounted for the majority of the total bud banks independently of the disturbance regimes. Our study suggests that the grasslands with a large reserve bud bank may be the most resistant to disturbance, and fencing is an effective grassland management measure to keep a large bud bank in typical steppe on the Loess Plateau.  相似文献   

7.
The overgrowing of meadow-bog communities by shrubs and trees (age 5–40 years, crown closure 0.4–0.9) leads to a decrease in incident illumination. As a consequence, juvenile and generative plants disappear from D. incarnata population loci, their average ecological density decreases, and the loci enter the state of regression. The digging activity of wild boars disrupts phytocenotically closed groups of longirhizomatous herbs, thereby creating favorable conditions for seed reproduction of D. incarnata. The species begins to form population loci with a complete ontogenetic spectrum and high ecological density, eventually restoring the normal (definitive) population structure.  相似文献   

8.
9.
长江三峡水库气候效应数值模拟   总被引:4,自引:0,他引:4  
在地形坐标系中建立了一个三维静力平衡的大气-土壤耦合模式,模式详细考虑了复杂地形、植被和水面的热力、动力过程。与其它中、小尺度模式相比其独特之处是:此模式在地表与植被冠层建立的辐射平衡方程和能量平衡方程中,均详细地考虑了坡度、坡向的影响。观测表明,长江三峡江面水温的日变化小于3℃。长江三峡段水流湍急,江水上下交换十分剧烈,各处水深变化较大,使模拟江水的动力、热力过程变得十分困难。所以,在研究中忽略了江水温度的日变化,模式中作为动力、热力外强迫因子,水库建成后的改变仅为水面海拔高度的升高和水面区域的扩大,水面温度是常数。用此模式模拟研究长江三峡建成前后气象要素场的日变化过程,通过计算它们的差别来分析水库的小气候效应。结果表明风、温、湿气象要素场在方圆近10 km范围内均有不同程度的改变,但变化幅度不大。  相似文献   

10.
Mountains of the northern Mediterranean basin face two major threats under global change. Aridity and available fuel are both expected to increase because of climatic and land-use changes, increasing fire danger. There may already be signs of such effects in the case of the Pinus nigra and Abies cephalonica forests on Mt. Taygetos (southern Greece). We reconstructed climate (mid- to late-fire-season drought) using tree-rings for the last 150 years and compared it with the mountain’s fire history reconstructed from P. nigra fire scars. Seven, out of the ten, large fires Mt. Taygetos experienced were associated with below-normal precipitation (P) or above-normal maximum temperature (T max). The largest fires occurred in late summer of 1879, 1944, 1998, and 2007. However, only the recent fires (1998 and 2007) had both low P and high T max, also confirmed from long-term meteorological data. The synergy between climate and fuel availability may explain the very high intensity of 1998 and 2007 fires that burned mostly as stand-replacing crown fires. The other two large fire events (1879 and 1944) most likely occurred under reduced availability in burning fuel and were related to above-normal T max. Our findings are among the first based on long-term and site-specific empirical data to support the prediction that Mediterranean mountainous areas will face a very large threat from wildfires in the twenty-first century, if socioeconomic changes leading to land abandonment and thus burning fuel accumulation are combined with the drought intensification projected for the region under global warming.  相似文献   

11.
Many traditional models of vegetation canopy reflectance have commonly used one of two approaches. Either the canopy is assumed to consist of discrete objects of known reflectance and geometric-optics are then used to calculate shading effects, or, as in the turbid medium approach, the canopy is treated as a horizontally homogeneous layer of small elements of known optical properties and radiative transfer theory is used to calculate canopy reflectance. This paper examines the effect of solar zenith angle on the reflectance of red and near-infrared radiation from forests using a combination of these modelling approaches. Forests are first modelled as randomly spaced eucalypt crowns over a homogeneous understorey and the fractional coverage of four components: shaded and sunlit canopy and shaded and sunlit understorey are calculated. Reflectance from each fraction is then modelled for a range of solar zenith angles using the Verhoef SAIL model. The overall scene reflection as seen by a nadir viewing satellite sensor is compared for three forest types representing a gradient of crown density from open dry grassy woodlands to dense wetter closed forest with an understorey of mesophytic plants. Modelled trends in scene reflectance change are consistent with aircraft measurements carried out at three different solar zenith angles. Results indicate that an increase in both tree density and solar zenith angle leads to an increase in the dominance of shaded components. In the visible band, both the sparsely treed woodland and the medium density dry forest show similar trends to that predicted by a turbid medium model, however, the wet forest shows a less rapid decrease in reflectance with solar zenith angle. In the near-infrared band, as tree density increases from woodland to wet forest, overall scene reflectance shows increased departure from that modelled using the traditional assumption of smooth homogeneous canopies, changing from an increase with solar zenith angle for the woodland to a decrease with solar zenith angle for the forest types.  相似文献   

12.
为了客观认识大别山五针松(Pinus dabeshanensis)与其所在群落中主要优势种的种间关系,采用样方法进行群落调查,然后用χ2检验、Ochiai关联指数、Pearson相关分析和Spearman秩相关分析法对天马自然保护区大别山五针松群落中大别山五针松与其它14个优势树种的种间联结和相关性进行了研究。结果表明:Spearman秩相关分析结果灵敏度较高,表明大别山五针松(Pinus dabeshanensis)与黄山松(Pinus taiwanensis)、短柄枹(Quercus glandulifera var brevipetiopetiolata)、栓皮栎(Quers variabilis)、天目杜鹃(Rhododendron fortunei)呈极显著正相关,与茅栗(Castanea seguinii)、五角枫(Acer mono)呈显著正相关。与白檀(Symplocos paniculata)呈极显著负相关,与蜡瓣花(Corylopsis sinensis)、荚蒾(Viburnum dilatatum)呈显著负相关。据以上分析,可把大别山五针松、黄山松、短柄枹、栓皮栎、天目杜鹃、茅栗和五角枫划为一个生态种组。保护和管理大别山五针松时,控制群落中非同一生态种组的物种,如白檀、蜡瓣花、荚蒾等,从而促进大别山五针松尽快郁闭成林  相似文献   

13.
实施生态补偿制度是保障黄河三角洲高效生态区可持续发展的基础。该文在明晰黄河三角洲高效生态区生态补偿原则和利益相关方各自的责任和义务的基础上,提出并设计了黄河三角洲高效生态区生态补偿平台建设思路和生态补偿运行机制。生态补偿平台建设主要包括:建立由政府主导的生态补偿交易市场平台;建立以生态补偿保险、生态补偿期货、互助基金、证券化交易为主要内容的生态补偿风险保障平台;建立以相关独立认证和监测(检测)、资产评估、审计、代理等机构组成的生态补偿交易中介服务平台;建立生态补偿监管平台。生态补偿运行机制需要将法制建设、财政扶持、税收调节和保障措施等系统化:推进《生态补偿法》、《黄河三角洲高效生态区补偿协定》的制定;完善并建立中央财政转移支付、财政转移制度纵向化、"环境财政"等制度;改革创新区域或专项税收制度;构建完备的生态补偿评估、考核、监督管理体系,等等。  相似文献   

14.
凤凰城旅游景区转让后的效应评价   总被引:7,自引:0,他引:7  
在我国经济市场化改革的大背景下,转让景区经营权、实行企业化运作成为一些风景名胜区经营管理改革过程中的一种制度创新模式。地处西部大开发战略图中的湘西凤凰县由于在旅游开发中受到了资金缺口和管理瓶颈的双重制约,于2001年底将其辖域内的八大景区(点)的50年经营权转让给了湖南黄龙洞投资股份有限公司。景区经营权转让是一个十分复杂而敏感的话题。本文避开关于景区经营权转让的各种是非争论,基于对旅游地社区各利益主体以及旅游者的实地调查和访谈记录分析,对凤凰景区企业化运作三年来的绩效与影响作了较为客观的评估,并就如何完善景区企业化运作模式、规避经营管理风险和负面影响等提出了相关理论思考和政策建议。  相似文献   

15.
The main regulatory mechanism of populations is revealed for some insect groups (Carabidae, Curculionidae, Chrysomelidae, and Hemiptera) on islands of the Kuibyshev Reservoir. This mechanism is the dynamics of the ratio of species with imaginal and preimaginal winter diapause. The extent of these dynamics depends on the stability of habitats, which in turn depends on water-level conditions in the reservoir. The period of adaptation of the community of carabids of the most flooded biotope to the extreme impact of water conditions is determined.  相似文献   

16.
作为当代环境伦理学之生态中心论的代表,克里考特以新物理学与生态学的视角引向后现代主义的整体观。这一思路指向的是整体论系统观的范式,后者具有四项特征:1整体的性质不能被还原为部分的性质;2整体是部分形成的原因与依据;3部分是系统地互相联系的;4部分是内在地互相联系的,即关系决定存在。以该整体论系统观的范式为依据,克里考特的后现代视域既涉及本体论,也指向价值论。在本体层面,克里考特借鉴了深生态学中"充分实现的自我"的概念试图解构笛卡尔的主客二分。进而,在削弱现代哲学中三类性质(数量性、质量性与价值性)区分的同时,克里考特提出了"实质价值"的概念,并试图以实质价值消解内在价值的同时统摄固有价值与工具价值。在文本梳理的基础上,本文也考察了克里考特的后现代视域的逻辑依据与实践可能。具体地,本文指出:1克里考特以实证科学之认知来架构形上本体的思路混淆了科学命题与玄学命题的区别内涵;2建立在消解三类性质基础上的"实质价值"架空了价值本身的应然引力;3克里考特过分地强调了整体与部分的对立从而容易陷入逻辑悖论;4克里考特以关系消解实体的本质是将关系作了唯内在性的理解,而这种理解是缺乏支持力的。特别地,克里考特以整体解析部分并以关系消解个体的进路将导致伦理虚无主义。针对克里考特理论的缺陷,本文指出,以"关系"为纽结的部分与整体之间是体用统一的;而实体间的关系,既具有内在性的一面,也具有外在性的一面;并且,关系的外在性既具有本然的维度,也具有应然的维度,即,它是道德实践的必要前提。  相似文献   

17.
The article establishes an evaluation index system of the intensive land use from the perspective of enterprises. It is based on the questionnaire survey and evaluates the levels of the intensive use of the land in the electrical machinery and equipment manufacturing industry in Changzhou, Nantong, and Yancheng of Jiangsu Province. The evaluation result shows that there is obvious difference in the levels of the intensive use of the land in this industry in the three cities. The present article makes a detailed analysis on the causes of the difference. The analysis shows difference in results of the socio-economic and urban development stage, industrial features, population density, and technological progress. Finally, it proposes some suggestions to improve the efficiency of the industrial land use.  相似文献   

18.
Northern Rangelands of Kenya have continued to grapple with management challenges largely due to a lack of understanding of the dynamics thereof. Eroding customary institutions and new institutional arrangements characterize the system suggesting that adaptation is taking place to cope with the change. It is imperative that these socio-ecosystems adjust to the disturbance without disintegrating into a different state that is controlled by a different set of processes to ensure sustainable rangeland management. To understand the nature of change, the study sought to evaluate institutional arrangements engaged in tackling growing socio-economic and ecological factors challenging development within the last decade. Three study sites namely Kinna, Makurian and Westgate, representing three types of institutional arrangements (elders only, group ranch committee and community conservancy board), were investigated. Key informants, focused group discussions and household survey methods were used to gather data. Data were managed and analysed using Ms Access, Ms Excel, social network analysis and SPSS. Findings indicate that more actors (internal and external) are engaging in management of social economic and ecological factors challenging development within the last decade. The co-management approach allows increased capacity to tackle these challenges and further presents more opportunities for a diversified livelihood, two key features of ecosystem resilience. Findings are useful as the Kenya government implements the National Land Policy that recognizes the need to restructure community land and its management.  相似文献   

19.
以加入WTO为标志.中国积极参与经济全球化已成为一种必然.但由于我国的国土规模、自然环境、气候条件等方面的地区差异很大,地区之间在发展水平上一直存在着差距,地区发展不平衡是个长期的国内政治经济现象.这种地区发展的差距表现为各类地区融入经济全球化的程度不同,反应不同.有些地区能够借助经济的全球化而发展自身,有些地区则无法从中受益,甚至因而处于更加落后的境地.本文从三大经济地带、各经济区和各省(市)区三个屡次分析和探讨了不同区域对经济全球化响应的差异,并对全球化条件下我国内部区域一体化格局进行了深入的研究.  相似文献   

20.
地质旅游研究进展   总被引:1,自引:0,他引:1  
自20世纪70年代以来,地质旅游受到世界各国的重视,并在国内外相关领域的研究中积累了丰富的经验和文献。本文从地质旅游的含义、地质旅游活动发展历程和国内外理论与实践建设出发对地质旅游进行归纳和总结。综述表明,地质旅游越来越受到游客、地方和政府的关注和重视,是一重要的生态和可持续旅游型式。  相似文献   

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