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151.
雾灵山自然保护区维管植物区系的研究   总被引:10,自引:2,他引:10  
冯天杰  李东义 《植物研究》1999,19(3):259-267
雾灵山自然保护区有自生维管植物117科520属1532种(含种下单位175个)分别占河北省维管植物科,属,种数的79.1%,69.4%,72.7%,是河北省维管植物丰富区域之一,本区植物工区系属较多,种数相对较少;木本植物少,多年生草本植物占绝对优势,具有典型的北温带性质。  相似文献   
152.
北京松山自然保护区大型真菌调查初报   总被引:9,自引:0,他引:9  
蔡怀頫  刘红霞  郭一妹  崔国发 《生态科学》2003,22(3):250-251,244
松山自然保护区是北京市的国家级保护区,具有暖温带北段典型的自然景观,保护对象为天然油松林和落叶阔叶林森林生态系统。此次报道了松山自然保护区部分地区大型真菌的初步调查结果,采用目前国内外普遍使用的Ainsworth(1973)的分类系统进行分类。采集到的这些大型真菌隶属于2个亚门,4目,16科,31种,其中食用、药用菌23种,木腐菌7种,外生菌根菌7种,有毒真菌6种。松山自然保护区内有丰富的物种多样性,动植物资源比较丰富,有益的食用菌、药用菌及菌根真菌种类相对较多,菌物资源的开发与利用潜力较大。  相似文献   
153.
Recent demonstrations of the role of plant–soil biota interactions have challenged the conventional view that vegetation changes are mainly driven by changing abiotic conditions. However, while this concept has been validated under natural conditions, our understanding of the long‐term consequences of plant–soil interactions for above‐belowground community assembly is restricted to mathematical and conceptual model projections. Here, we demonstrate experimentally that one‐time additions of soil biota and plant seeds alter soil‐borne nematode and plant community composition in semi‐natural grassland for 20 years. Over time, aboveground and belowground community composition became increasingly correlated, suggesting an increasing connectedness of soil biota and plants. We conclude that the initial composition of not only plant communities, but also soil communities has a long‐lasting impact on the trajectory of community assembly.  相似文献   
154.
This study was conducted to determine if correlations exist between the numbers of microscopic follicles comprising ovarian follicular reserve (OFR) and antral follicle counts (AFCs), and to assess the usefulness of computerized analyses of ovarian ultrasonograms and magnetic resonance (MR) images for estimating OFR in excised porcine, ovine and bovine ovaries. As a pre-requisite to these analyses, we characterized and compared ovarian cortical histomorhpology and follicle populations in the three species varying in prolificacy and overall reproductive longevity, and hence the total number of microscopic and antral follicles. Ultrasonographic and MR images were obtained at the scanner settings optimized to provide opposing contrasts between antral follicles and the ovarian stroma. Commercially available ImageProPlus® analytical software was used to calculate numerical pixel values (NPVs) and pixel heterogeneity (standard deviation of the pixel values) along the computer-generated lines (4–6) placed in the area corresponding to the ovarian cortex. The numbers of primordial (r = 0.38, P < 0.01) and intermediate follicles (r = 0.37, P < 0.01) were correlated with the numbers of antral follicles in bovine ovarian sections. The numbers of primordial (r = 0.28, P < 0.05), intermediate (r = 0.31, P < 0.01) and primary follicles (r = 0.27, P < 0.05) correlated directly with mean NPVs of the ultrasonographic ovarian images in cattle. There was a negative correlation between primary follicle numbers and NPVs of MR images (3D FAST-SPOILED GRADIENT ECHO) of the porcine ovarian cortex (r = −0.31, P < 0.05). To summarize, the numbers of primordial and intermediate follicles could only be estimated from AFCs in cows. Using ultrasound NPVs, the numbers of primordial, intermediate and primary follicles could be directly estimated in bovine ovaries and the quantitative image attributes of MR images were useful for quantifying porcine primary follicles. The bovine ovarian model is compatible with human situation and hence future studies should be undertaken to ascertain the usefulness of AFCs and ultrasonographic image analyses for estimating OFR in women.  相似文献   
155.
We tested the effects of four data characteristics on the results of reserve selection algorithms. The data characteristics were nestedness of features (land types in this case), rarity of features, size variation of sites (potential reserves) and size of data sets (numbers of sites and features). We manipulated data sets to produce three levels, with replication, of each of these data characteristics while holding the other three characteristics constant. We then used an optimizing algorithm and three heuristic algorithms to select sites to solve several reservation problems. We measured efficiency as the number or total area of selected sites, indicating the relative cost of a reserve system. Higher nestedness increased the efficiency of all algorithms (reduced the total cost of new reserves). Higher rarity reduced the efficiency of all algorithms (increased the total cost of new reserves). More variation in site size increased the efficiency of all algorithms expressed in terms of total area of selected sites. We measured the suboptimality of heuristic algorithms as the percentage increase of their results over optimal (minimum possible) results. Suboptimality is a measure of the reliability of heuristics as indicative costing analyses. Higher rarity reduced the suboptimality of heuristics (increased their reliability) and there is some evidence that more size variation did the same for the total area of selected sites. We discuss the implications of these results for the use of reserve selection algorithms as indicative and real-world planning tools.  相似文献   
156.
Scrub vegetation is a valuable habitat and resource for wildlife, but if unmanaged can encroach and dominate adjacent habitats, reducing biodiversity value. A primary task in the management of terrestrial nature reserves in the UK is monitoring and controlling scrub. The methods used to monitor and assess scrub cover are often basic, relying on qualitative assessment. Inaccurate assessments may fail to inform appropriate management of the habitats and lead to loss or degradation of important ecological features. Scrub can be monitored using UAV or satellite‐derived imagery, but it can be difficult to distinguish between other vegetation types without using high‐cost hyperspectral sensors. An alternative method using high‐resolution surface models from photogrammetric point clouds enables the isolation of vegetation types based on height. Scrub can be isolated from woodland, hedgerows, and tall ground vegetation. In this study, we calculate scrub cover using a photogrammetric point cloud modeling approach using UAVs.We illustrate the method with two case studies from the UK. The scrub cover at Daneway Banks, a calcareous grassland site in Gloucestershire, was calculated at 21.8% of the site. The scrub cover at Flat Holm Island, a maritime grassland in the Severn Estuary, was calculated at 7%. This approach enabled the scrub layer to be readily measured and if required, modeled to provide a visual guide of what a projected management objective would look like. This approach provides a new tool in reserve management, enabling habitat management strategies to be informed, and progress toward objectives monitored.  相似文献   
157.
BackgroundCoronary computed tomography angiography (CCTA) is widely used in the diagnostic work-up of patients with stable chest pain. CCTA has an excellent negative predictive value, but a moderate positive predictive value for detecting coronary stenosis. Computed tomography-derived fractional flow reserve (FFRct) is a non-invasive, well-validated technique that provides functional assessment of coronary stenosis, improving the positive predictive value of CCTA. However, to determine the value of FFRct in routine clinical practice, a pragmatic randomised, controlled trial (RCT) is required. We will conduct an RCT to investigate the impact of adding FFRct analysis in the diagnostic pathway of patients with a coronary stenosis on CCTA on the rate of unnecessary invasive coronary angiography, cost-effectiveness, quality of life and clinical outcome.MethodsThe FUSION trial is a prospective, multicentre RCT that will randomise 528 patients with stable chest pain and anatomical stenosis of ≥ 50% but < 90% in at least one coronary artery of ≥ 2 mm on CCTA, to FFRct-guided care or usual care in a 1:1 ratio. Follow-up will be 1 year. The primary endpoint is the rate of unnecessary invasive coronary angiography within 90 days.ConclusionThe FUSION trial will evaluate the use of FFRct in stable chest pain patients from the Dutch perspective. The trial is funded by the Dutch National Health Care Institute as part of the research programme ‘Potentially Promising Care’ and the results will be used to assess if FFRct reimbursement should be included in the standard health care package.Supplementary InformationThe online version of this article (10.1007/s12471-022-01711-w) contains supplementary material, which is available to authorized users.  相似文献   
158.
159.
An important component of recent nature conservation is the ecological restoration of semi-natural grasslands. The aim of such projects is usually the restoration of typical plant communities; translocation of animals, by contrast, plays only a minor role. This is based on the assumption that a recovery of the flora will lead to recovered fauna; however, this is not always the case. Suction samplers with gauze collection bags are well suited to sample arthropods, and they may also be helpful for transferring animals. However, to date, the suitability of suction samplers as a translocation tool is unclear due to a lack of empirical data on the mortality rate of the sampled arthropod taxa. In this study, we sampled arthropods (leafhoppers, spiders, beetles, and true bugs) with a suction sampler on 21 calcareous grasslands. Immediately after sampling, animals were stored in collection bags and their mortality rate was determined. We compared storage periods (1, 2, and 3 h) and tested the suitability of a cool box to reduce mortality rates. Our study revealed that arthropod mortality was generally low (9% of all sampled individuals); however, the survival rate was affected by (1) storage time, (2) storage conditions, and (3) arthropod group. The mortality of beetles and true bugs was very low and not influenced by storage time or storage conditions. In contrast, leafhoppers and spiders had higher mortality, which increased with storage time and decreased by the use of a cool box. According to our results, suction samplers can be a valuable tool to sample arthropod assemblages for conservation translocation. In order to reduce mortality in sensitive groups such as leafhoppers and spiders, the storage process can be optimised. We thus recommend (1) using a cool box and (2) minimising the period until release of the collected arthropods at the restored site.  相似文献   
160.
中华秋沙鸭越冬行为时间分配及日活动节律   总被引:1,自引:1,他引:1  
易国栋  杨志杰  刘宇  左斌  赵匠  郝锡联 《生态学报》2010,30(8):2228-2234
2007年12月-2008年1月和2008年11-12月,在江西省境内4条主要河流及其支流对中华秋沙鸭(Mergus squamatus)越冬期的各种行为活动节律及时间分配进行了实地调查研究。结果表明:中华秋沙鸭越冬期的主要行为有取食、游泳、理羽、静息、睡眠、游戏、飞行和观察。其中取食、游泳、理羽、静息呈明显的节律性变化,且取食与静息呈相反的节律变化;睡眠、飞行、游戏和观察没有明显的节律性变化。取食在7:00-8:00、10:00-11:00、12:00-13:00有明显的峰值,峰值平均间隔2.3h,其它时段具相近取食频次,且上午高于下午。睡眠和静息下午发生频次明显高于上午,并呈现节律性变化,对应3个取食高峰表现为低频次。行为时间分配如下:取食(46%),游泳(23%),理羽(9%)、静息和睡眠(各占8%)、飞行(4%)、游戏(2%)和观察(0.5%)。越冬期中华秋沙鸭大量时间用于取食,意图是为了积累能量。相关分析表明:取食与睡眠的发生呈显著负相关(R=-0.73,df=8,P0.05);取食与飞行的发生呈显著正相关(R=0.70,df=8,P0.05);理羽与静息的发生呈极显著正相关(R=0.88,df=8,P0.01);其他各种行为之间无显著相关性。  相似文献   
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