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Depending on season, rainfall characteristics and tree species, interception amounts to 15–50% of total precipitation in a forest under temperate climates. Many studies have investigated the importance of interception of different tree species in all kinds of different climates. Often authors merely determine interception storage capacity of that specific species and the considered event, and only sometimes a distinction is made between foliated and non‐foliated trees. However, interception is highly variable in time and space. First, since potential evaporation is higher in summer, but secondly because the storage capacity has a seasonal pattern. Besides weather characteristics, such as wind and rain intensity, snow causes large variations in the maximum storage capacity. In an experimental beech plot in Luxembourg, we found storage capacity of canopy interception to show a clear seasonal pattern varying from 0·1 mm in winter to 1·2 mm in summer. The capacity of the forest floor appears to be rather constant over time at 1·8 mm. Both have a standard deviation as high as ± 100%. However, the process is not sensitive to this variability resulting only in 11% variation of evaporation estimates. Hence, the number of raindays and the potential evaporation are stronger driving factors on interception. Furthermore, the spatial correlation of the throughfall and infiltration has been investigated with semi‐variograms and time stability plots. Within 6–7 m distance, throughfall and infiltration are correlated and the general persistence is rather weak. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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国家速滑馆建筑结构在空间上的不规则性、多样性、复杂性及超大规模给施工测量带来较大的难度,因此,加强对动态高精度测量技术的研究和应用,是实现施工过程各专业、各环节高精度搭接的重要基础。国家速滑馆动态高精度施工测量关键技术解决了不均匀作用力下大跨度马鞍形索网同步张拉困难的技术难题;突破了特大异形柔性结构屋顶预制、安装和调控精密测量关键技术,实现了精密工程测量从静态到动态、离散到连续的转变;形成了模型驱动的一测多用高密度网状排管表观形态高效测量新方法;解决了受阻或封闭环境长距离连续面超高精度地坪标高测量难题,有效指导了施工作业,为2022年冬奥会速滑项目的开展提供了保障。 相似文献
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不同林龄人促更新林枯枝落叶层碳及养分贮量 总被引:1,自引:0,他引:1
对福建南平顺昌县不同林龄米槠(Castanopsis carlesii)人促更新林枯枝落叶层和主要营养元素现存量进行测定,探究其随林龄的变化趋势。结果表明:不同林龄米槠人促更新林枯枝落叶层现存量为3.94~4.95 t·hm-2,其中49 a生人促林枯枝落叶层现存量最小,31 a生的最大。不同林龄枯枝落叶层C、N、P、K的浓度分别为44.09%~47.46%,11.9~13.8 g·kg-1,0.5~0.9 g·kg-1,1.4~5.1 g·kg-1。21 a生和49 a生人促更新林枯枝落叶层C浓度明显高于31 a生林分。49 a生人促更新林枯枝落叶层N和P浓度均高于21 a生和31 a生林分,但该林分枯枝落叶层K浓度却最低。21 a生米槠人促更新林枯枝落叶层C贮量分别是31 a生和49 a生林分的1.03倍和1.23倍,49 a生米槠人促更新林K贮量远低于21 a生和31 a生。不同林龄枯枝落叶层碳和养分贮量差异与林分特征、各林分枯枝落叶层现存量及养分浓度等有关。 相似文献
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Pyrogenic carbon (PyC), a by-product of recurrent boreal wildfires, is an important component of the global soil C pool, although precise assessment of boreal PyC stock is scarce. The overall objective of this study was to estimate total C stock and PyC stock in forest floors of Eastern Canada boreal forests. We also investigated the environmental conditions controlling the stocks and characterized the composition of the forest floor layers. Forest floor samples were collected from mesic black spruce sites recently affected by fire (3–5 yr) and analyzed using elemental analysis and solid state 13C nuclear magnetic resonance (NMR) spectroscopy. PyC content was further estimated using a molecular mixing model. Total C stock in forest floors averaged 5.7 ± 2.9 kg C/m2 and PyC stock 0.6 ± 0.3 kg C/m2. Total stock varied with position in the landscape, with a greater accumulation of organic material on northern aspects and lower slope positions. In addition, total stock was significantly higher in spruce-dominated forest floors than stands where jack pine was present. The PyC stock was significantly related to the atomic H/C ratio (R2 0.84) of the different organic layers. 13C NMR spectroscopy revealed a large increase in aromatic carbon in the deepest forest floor layer (humified H horizon) at the organic-mineral soil interface. The majority of the PyC stock was located in this horizon and had been formed during past high severity fires rather than during the most recent fire event. 相似文献
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新店东井田构造复杂、断层多且落差大,破坏了其原有的水文单元,使得大气降水、地表水、地下水联系的更加紧密。根据地质资料分析,本区先期地段内主要断层均切割至二叠系茅口组,缩短了煤层与二叠系茅口组的间距,使得更易发生茅口组突水。 相似文献
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随着实景三维建设的不断推进,城市管理向立体化、精细化和数字化发展,建筑分层分户三维模型能够承载更详细精准的属性信息,并能叠加倾斜三维模型进行场景渲染,可以更好地服务于城市不动产三维管理、数字赋能社会治理等工作。本文以“萧山区数字赋能社会治理”项目建设为背景,探索和实现了基于不动产登记数据的建筑分层分户三维建模关键技术,形成了从全空间多源异构数据归集至城市全域建筑分层分户三维模型建设的一整套生产技术流程,为城市不动产三维管理、数字赋能社会治理等提供了有效的技术支撑和数据基础。 相似文献
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新型预制楼盖的装配整体式框架剪力墙结构振动台试验研究 总被引:2,自引:0,他引:2
基于发展装配式建筑是实现建筑节能的重要举措,从楼盖要满足平面内刚性的要求,结合实际工程进行了不加后浇面层的新型预制楼盖的中间钢板剪力墙边榀钢框架三层结构模型的振动台试验,并对采用新型预制板和新型连接的装配整体楼盖的面内变形、传递水平地震作用力的性能进行了分析.研究结果表明:采用新型预制板和新型连接的不加后浇面层楼盖的刚性可以保证结构的空间整体性和水平力的有效传递,在高烈度地区可以考虑用不加后浇面层的装配整体式楼盖代替现浇楼盖. 相似文献