Plant distribution at the mobile dune scale and its relevance to soil properties and topographic features     

Xiaoan Zuo  Halin Zhao  Xueyong Zhao  Yirui Guo  Yulin Li  Yayong Luo 《Environmental Geology》2008,54(5):1111-1120

A survey was conducted in an 11-year recovery mobile dune (RMD11) and a 20-year recovery mobile dune (RMD20), in Horqin Sandy Land, Northern China, to determine plant distribution at the mobile dune scale and its relevance to soil properties and topographic features. The results showed that (1) vegetation cover and species number increased from dune top to bottom in the restoration process of mobile dune; (2) the average value of soil organic C, total N, pH, relative height of sampling site, very fine sand content and soil water contents (40−60 and 60−80 cm) of RMD11 were less than that of RMD20, respectively, and there were significant differences (P < 0.05) between the two dunes; (3) soil resources were redistributed by shrub restoration and relative height of sampling site on dune. The distribution of sand pioneer plant, Agriophyllum squarrosum, was positively related to the relative height of sampling site and soil water content, while that of other herbaceous plants was positively related to soil nutrients in the restoration process of mobile dune. These results suggest that at mobile dune scale, plant distributions are determined by a combination of soil properties and topographic feature. Much effort should be made to preserve the interdune lowland and to improve the level of soil nutrients on mobile dune.  相似文献   

中国红树林生态系统的植物种类、多样性、功能及其保护   总被引：28，自引：0，他引：28  

林益明  林鹏 《海洋湖沼通报》2001,(3):8-16

本文从4个方面对中国红树林生态系统的植物进行论述：（1）中国红树林生态系统的红树植物、半红树植物、伴生植物、红树林区的大型藻类和浮游植物种类；（2）中国红树林生态系统植物的物种多样性、红树植物生理和形态适应的多样性、产物的多样性；（3）红树林的生态功能；（4）中国红树林生态系统的主要保护问题及其保护措施。  相似文献   

黑河中下游荒漠区植物多样性分布对土壤水分变化的响应   总被引：9，自引：0，他引：9  

李新荣  何明珠  贾荣亮 《地球科学进展》2008,23(7):685-691

基于对黑河流域中下游荒漠区植被和土壤生境的调查分析,以土壤水分在各调查样地中的差异来反映研究区的生态水文特征,采用种的丰富度和多度来代表荒漠植物多样性研究了荒漠植物,包括隐花植物多样性分布对土壤水分变化的响应。土壤水分变化不仅直接影响着荒漠植物的多样性,而通过影响其它生境因子又间接地影响着多样性的维持。因此,如何维持中下游相对稳定的土壤水分来源是该区荒漠植物多样性保育今后所要面临的挑战。  相似文献   

生物多样性遥感研究进展   总被引：3，自引：0，他引：3  

魏彦昌  吴炳方  张喜旺  杜鑫 《地球科学进展》2008,23(9):924-931

随着遥感技术和新型传感器的发展,遥感已成为目前区域或全球生物多样性研究的重要方法。综述了目前国内外生物多样性遥感研究的最新进展;分析了遥感生物多样性研究的主要理论基础,包括光谱变异假说、生产力假说和种—面积关系理论等;总结了利用高空间和高光谱分辨率遥感数据直接监测生物物种及其多样性的进展与局限性;基于遥感反演的不同环境变量进行生物多样性模拟和预测是目前最常用的方法,对其进行了较详细的分析,并介绍了相关模型的发展。最后,总结了该方法在我国的应用局限,指出增进学科合作、将遥感方法与生态学理论和模型相结合、重视地面验证数据的使用将是生物多样性遥感研究的发展趋势。  相似文献   

Lake-Level Fluctuations and Small-Scale Vegetation Patterns During the Late Glacial in The Netherlands     

Johanna A. A. Bos  Sjoerd J. P. Bohncke  C. Roel Janssen 《Journal of Paleolimnology》2006,35(2):211-238

Late glacial changes in the vegetation were studied in and around a former lake on the southeastern side of a coversand ridge near Milheeze (southern Netherlands). Analyses of microfossils and macroremains and AMS ¹⁴C dating were performed on four sediment cores along a transect from sand ridge to the lake centre. Small-scale vegetation patterns and lake-level fluctuations were reconstructed in detail based on the information provided by the transect. For the first time in The Netherlands, cores along a transect within one lake were used to reconstruct the amplitude of late glacial lake-level fluctuations. Near Milheeze, a small and shallow lake was formed during the Bølling. The large increase in the water level during the Bølling and early Allerød, and the transition to more eutrophic conditions at the start of the Allerød, were probably related to the disappearance of permafrost. During the Allerød, open birch and pine woodlands developed in the area. In the lake, organic deposits accumulated, and the lake size and depth fluctuated. At the start of the Younger Dryas, higher lake water levels were recorded and woodlands became more open as a result of both a drop in the temperature and an increase in the effective precipitation. During the late Younger Dryas the lake water level dropped as the climate became drier and temperatures slightly increased. Accumulation of organic deposits in the lake ceased at the end of the Younger Dryas, which was caused by a drop in the water level in combination with the hydroseral succession process within the lake itself. The climatic signal reflected in the late glacial flora and lake-level fluctuations agree well with other published data from The Netherlands.  相似文献   

新疆尼勒克县巴斯尔干地区植物化石的发现及意义     

凌联海  楼法生  肖晓林  吴新华  吴明仁  蒋金明 《新疆地质》2005,23(1):28-30

新疆尼勒克县巴斯尔干地区有一套棕黄、褐红色砂砾岩，过去仅采获硅化木化石，根据岩性对比将其归属早白垩世．根据最近采获的植物化石资料，论证了该区巴斯尔干组地质年代为二叠纪乐平世．岩石地层单位称巴斯尔干组。  相似文献   

地震作用下的灰坝液化特征及其动力稳定性分析--以安阳电厂为例   总被引：1，自引：0，他引：1  

李永乐  陈宇  彭成山  刘宪亮 《地质科技情报》2002,21(1):83-86

根据安阳电厂灰坝岩土工程性质及其动力学特性,建立了适合灰坝工程的动力分析模型并采用有限元法进行了动力分析.在此基础上,在不同工况条件下对灰坝进行了抗液化安全评价及抗震稳定性分析.研究表明,在不设碎石桩、无排渗体条件下,粉煤灰子坝的抗液化安全系数Ks＜1.25,将发生液化;在设碎石桩、有排渗体条件下,粉煤灰子坝的抗液化安全系数明显提高,Ks≥1.25,不会发生液化.抗震稳定性分析表明,在上述两种工况条件下灰坝是稳定的.  相似文献   

Characterisation of riparian woodlands and their potential water loss in the distal Okavango Delta, Botswana     

Susan Ringrose   《Applied geography (Sevenoaks, England)》2003,23(4):281-302

An analysis is undertaken to develop techniques to remotely sense relative evapotranspiration outputs in the distal Okavango Delta using enhanced thematic mapper and ground based techniques to help quantify water loss. Much of this work focuses on riparian woodlands which, especially in the distal portion of the Delta, are regarded as being significant in terms of groundwater removal by transpiration. This was confirmed as vegetation cover mapping led to the identification of two riparian classes which, by association with high resistivity aeromagnetic data, were found to be rooted in near surface fresh groundwater. This paper indicates that riparian trees which remain green year long, partly sustain their growth as a result of groundwater uptake. A comparison of frequently flooded and dry floodplains with distinct riparian zones was undertaken using spectral techniques (pixel radiance values and leaf water content indices) to determine whether flooding and lateral groundwater flow stimulated growth (and therefore transpiration rate) following dormancy. Results indicate a basic similarity between the two systems with mixed evidence of assumed leaf growth. Related phenological observations in the riparian zone of the dry floodplain show that renewal of leaf growth is primarily related to rainfall, not flood events in the distal Delta. The results of this work should help effect both surface and groundwater management in the vicinity of population centres in the distal Delta.  相似文献   

LANDSCAPE PERMANENCE AND NUCLEAR WARNINGS     

MARTIN J. PASQUALETTI 《Geographical review》1997,87(1):73-91

ABSTRACT. From the perspective of a human lifetime, the hazards of some nuclear wastes are permanent, so the warnings we place at contaminated nuclear sites must be permanent too. I address questions of how best to provide one hundred centuries of public warning at the first facility for permanent disposal, the Waste Isolation Pilot Plant in New Mexico. Scenarios of intrusion developed to guide the design of warning markers predicted that most of the changes in the area will be social and cultural. Because blatant and permanent markers will increase, not reduce, the probability of inadvertent intrusion, the most appropriate warning is a “landscape of illusion.” Such a landscape needs not permanent surface markers but underground warning devices beneath a soft surface marker. No warning can guarantee deterrence for 10,000 years, however.  相似文献   

Temporal variability in the maternal environment and its effect on seed size and seed quality in Flourensia cernua DC. (Asteraceae).   总被引：1，自引：0，他引：1  

S. Valencia-Díaz  C. Montaa 《Journal of Arid Environments》2005,63(4):686-695

The biological phenomenon commonly referred to as maternal effect occurs whenever the environment exerts an influence upon the mother that is later expressed in characteristics of her offsprings. For example, the environmental conditions experienced by a mother plant during flowering and fruiting can modify the quality of her descendants (seeds), and even interrupt their development. Between-year variation in minimum temperature and the classic, between-year variation in precipitation represent an unpredictable environment for winter blooming plants in arid zones. In this study, we investigated the effect of maternal environment (temperature and precipitation) on seed size and seed quality in F. cernua, over a 5-year period. Results indicated that the proportion of filled seeds, as well as their size, increased with higher absolute minimum temperatures during seed formation, and that, to a lesser extent, both the precipitation occurred during the same period and the annual precipitation also have a positive influence on seed size. In this way, environmental conditions prevailing during seed formation exerted a strong maternal effect on the size and quality of seeds produced and, probably also, in the developmental possibilities of F. cernua seedlings. This effect was subject to important, between-year variation.  相似文献