柑桔园林下穿透雨的分布特征

研究了柑桔林下穿透雨的分布特征,结果表明:在测定期间,穿透雨量占总降雨量的68.3%,5月的穿透雨量最大(245.1 mm),而穿透雨率最大值(73.3%)出现在8月。穿透雨量与降雨量具有显著相关性(p<0.01),而穿透雨率与降雨量和降雨强度的相关性均达到显著水平(p<0.05)。柑桔林下穿透雨显示出明显的空间变化,各观测点间穿透雨率具有显著性的差异,而且穿透雨的空间异质性(穿透雨率的变异系数CV)随着降雨量或降雨强度的增加而降低,聚类分析也显示出穿透雨在不同观测点间具有差异性。柑桔林下穿透雨呈现明显的聚集效应。     

二郎坪地体火山成因块状硫化物床体的成矿规律和找矿预测

东秦岭二郎坪地体夹持于瓦穴子断裂和朱夏断裂之间,主要由早古生代弧后盆地环境的火山沉积建造和晚古生代以来的花岗岩类侵入体组成。近期地质调查表明,二郎坪地体蕴涵重要的银、金、铜、铅、锌等矿床,是一个新的矿集区。本文总结了近几年实施的国土资源大调查项目成果,将矿床划分为铜锌型矿床、铅锌铜型矿床、铁(铜)型矿床、金(银)矿床和黄铁矿层等五大类,它们成矿物质同源,且与火山沉积作用时空关系密切,总体形成于早古生代二郎坪弧后盆地发育阶段的海底喷流沉积作用,与古生代活动大陆边缘成矿系统相关。作者按成矿系统的形成、发展和演化观点,总结了矿床的时空分布规律、找矿标志,认为二郎坪地体资源潜力较大,提出了6个找矿预测远景区。     

Analysis of the Spatio-temporal Evolution of Land Intensive Use and Land Ecological Security in Tianjin from 1980 to 2019

The problem of land ecological security directly threatens the sustainable development of many regions, and exploring the spatio-temporal characteristics of land ecological security is helpful for analyzing the land ecological patterns between regions and over time. Based on the interpretation of remote sensing image data for Tianjin in 1980, 2000, 2010 and 2019, supported by software such as ArcGIS and GeoDa, the changes of land use in the study area are calculated by using the land use dynamic degree. Then, the land ecological security index and spatial autocorrelation analysis methods are used to study the spatial correlations and internal heterogeneity of land ecological security in each district in Tianjin. The results show that: (1) The land use of Tianjin has changed dramatically in the past 40 years: the building land has been expanding, while the farmland and barren have been shrinking continuously. (2) The overall level of land ecological security is in the high security area, and Jizhou District is the highest, while the Central areas and Binhai are low. (3) The spatial heterogeneity of land ecological security is not obvious, but the spatial agglomeration is strong.     

地形对0604号"碧利斯"登陆台风暴雨的影响

利用NCEP再分析日资料和常规观测资料等,对2006年第4号强热带风暴"碧利斯"登陆后造成内陆暴雨特别是湘东南特大暴雨的成因进行了分析。结果表明,华南大范围暴雨带与低气压南部的一条切变—槽以及从低压西侧卷入的干、湿两股气流间形成的"湿度锋区"有关;而独立存在于湘东南的尺度较小而强度特大的一条NNE—SSW向的暴雨带则与罗宵山脉的地形影响有密切关系,地形强迫上升及其对暴雨的触发主要不在山坡上,而是在迎风坡气流上游平原地区(即湘东南),实况与理论估算和推断结果一致。由于气流在湘东南平地辐合上升,它的触发作用成为湘东南特大暴雨发生的重要原因。     

一个水文模型与区域气候模式耦合的数值模拟研究

在陆面过程方案中考虑精细的水模型有助于改善对区域水及气候的模拟。建立了一个考虑降水及入诊空间非均匀性的水模型，并将其并入陆面过程方案BATS中。通过区域气候模式耦合模拟试验，得到如下主要结论：陆面水的模拟对降水及入渗空间非均匀性的考虑非常敏感；考虑入渗非均匀性后，提高了径流系数，这与湿润地区水分平衡的观测结果更一致；入渗非均匀参数化方案的引入对区域水及气候模拟的影响比降水非均匀参数化方案的引入要大；不透水面积在区域中的考虑所揭示的特征与我国北方干旱化趋势是一致的。     

武汉区域分县可能最大降水预报研究

针对强降水过程预报,介绍了一种包含大尺度降水、不稳定能量释放、地形影响作用等因子的可能最大降水预报模型的建立方案。方案利用历史强降水过程资料和精细的地形资料,从暴雨的基本成因出发,构造了多个影响因子,分别设计了不稳定降水方程和地形影响降水方程。通过2007汛期业务试运行表明,同其它模式相比,该模型对暴雨有较强的预报能力,为防汛抗灾提供了可靠的气象决策依据,最大可能降低了暴雨洪涝灾害造成的损失。     

干旱和半干旱区油蒿对土壤空间异质性的响应

空间异质性影响种群的分布和波动。在对数据进行归一化处理的基础上,应用地统计学方法研究干旱和半干旱区两个气候带内油蒿对土壤空间异质性的响应。结果表明：在中等尺度（500 m样线,间隔10 m取样）上,腾格里沙漠沙坡头固定沙地土壤水分的空间异质性大于毛乌素沙地芹河半固定沙地,相应地,沙坡头地段油蒿密度、有机质、全氮和有效磷含量的空间异质性大于芹河地段,因而认为,土壤水分的空间异质性决定油蒿密度的空间异质性,进而又反作用于土壤养分的空间异质性。结合油蒿生物量的空间异质性分析认为,土壤水分的空间异质性并不总是能够影响植物生物量的空间异质性。进一步分析表明,对于沙坡头地区,适当进行放牧或者其他干扰,将有助于增大土壤属性的空间异质性,以促进油蒿植被的持续存在。     

城市灾害社会脆弱性研究热点问题评述与展望

对城市灾害社会脆弱性研究的热点问题及趋向进行了深入的梳理和总结。研究发现,现阶段社会脆弱性研究已经成为城市灾害脆弱性的重要研究范式,但学者们在城市灾害社会脆弱性综合维度的界定、脆弱性评估方法构建、社会脆弱性与灾害种类相关性判读以及研究尺度选取等方面存在明显的争议。对这些争议进行了深入探讨,并对未来城市灾害社会脆弱性研究进行了展望,以期为中国城市防灾减灾工作提供科学参考。     

The spatial pattern of grasses in relation to tree effects in an arid savanna community: Inferring the relative importance of canopy and root effect

Both aboveground and belowground processes play important roles in tree-grass interactions in savannas. Little consideration has been given to within-site heterogeneity in the strengths of co-occurring canopy and root effects of trees on grasses in savanna communities. Here, we attempted to correlate the spatial pattern of grass morphological traits with the strengths of canopy and root effects. The results from a spatial analysis suggested that the grass traits had lower variability within the operating domain of the root effect than within that of the canopy effect in sub-canopy areas; in contrast, the operating domain of the root effect presented higher variability of grass traits than that of the canopy effect in inter-canopy areas. Combined with root investigations on vertical distribution patterns, these results suggested that the root effect appeared to outweigh the canopy effect in the sub-canopy areas, where apparent vertical root separation between trees and grasses was shown; while the canopy effect could outweigh the root effect in the inter-canopy areas, where root separation was not observed. This study could provide correlative information on the relative importance of canopy and root effects, and has some useful implications on within-site heterogeneity in terms of aboveground and belowground components in savannas.     

古尔班通古特沙漠植被与环境关系分析

The Gurbantunggut Desert is the largest stable and semi-stable sand desert in China, yet few data exist on vegetation pattern and species-environment relationships for these diverse desert landscapes. The sand dunes of the survey area are mainly of the longi- tudinal form from north to south, but checkerboard-shaped and honeycomb-shaped forms are also present, with the height of 10-50 m. We measured vegetation and soil data on north-south transects and compared them with vegetation and soil data on east-west transects. Analysis revealed that the varying trend and strength of the species diversity, dominance and cover of the plant communities in the longitudinal and transverse directions across the landscape are significantly different. The results of CCA ordination show that the microhabitats of soil organic matter （OM）, soil salts （TS）, sorting index （ σ ）, topsoil water-content （SM） and pH relate to the differences in vegetation observed as differences in species assemblage from salt-intolerant ephemerals, micro-subshrubs and subshrubs to salt-tolerant shrubs and micro-arbors. The terrain （alt.） and soil texture （the contents of Mz and Ф 1） affect the spatial differentiation of many species. However, this spatial differentiation is not so marked on transects running longitudinally with the landscape, in the same direction as the dunes. The species of the desert vegetation have formed three assemblages under the action of habitat gradients, relating to three sections running transversely across the landscape, at right angles to the direction of the dune crests. In the mid-east section of the study area the topography is higher, with sand-lands or dune-slopes with coarse particles. Here the dominant vegetation comprises shrubs and subshrubs of Seriphidium santofium and Ephedra distachya, with large numbers of ephemeral and ephemeroid plants of Senecio subdentatus, and Carex physodes in spring and summer. On the soil of the dune-slopes in the mid-west of the study area, with coarse partic