نتایج جستجو برای: climatic drought

تعداد نتایج: 61486  

2017
Li-Hua Meng Jie Yang Wen Guo Bin Tian Guang-Jie Chen Yong-Ping Yang Yuan-Wen Duan

Climatic tolerance, especially drought tolerance, is one of the major factors shaping the geographic distributions of plant species. Thus, the general decline in rainfall from the Himalaya-Hengduan Mountains (HHM) to the inner Qinghai-Tibet Plateau (QTP) might account for the significant differences in species distributions and richness between the two regions. To test this hypothesis, we condu...

Journal: :natural environment change 0
ahmad nohegar professor, faculty of environment, university of tehran, iran maryam heydarzadeh ph.d. candidate in engineering watershed management, hormozgan university, iran

drought as a natural but temporary imbalance of water availability is the interaction between natural environment and human life resulting in diminished water resources availability and reduced carrying capacity of the ecosystems. drought indices are essential elements for an efficient drought monitoring system. these indices make the transforming information of climatic anomalies easier and al...

Journal: :desert 2013
a. nohegar m. heydarzadeh a. malekian

drought monitoring is a fundamental component of drought risk management. it is normally performed usingvarious drought indices that are effectively continuous functions of rainfall and other hydrometeorological variables.in many instances, drought indices are used for monitoring purposes. geostatistical methods allow the interpolationof spatially referenced data and the prediction of values fo...

Journal: :Evolution; international journal of organic evolution 2009
Jacob A Esselstyn Robert M Timm Rafe M Brown

Geological and climatic processes potentially alter speciation rates by generating and modifying barriers to dispersal. In Southeast Asia, two processes have substantially altered the distribution of land. Volcanic uplift produced many new islands during the Miocene-Pliocene and repeated sea level fluctuations during the Pleistocene resulted in intermittent land connections among islands. Each ...

2015
Donald A. Wilhite

The development and implementation of a drought policy is intended to alter a nation’s approach to drought management. A national drought policy should establish a clear set of principles or operating guidelines to govern the management of drought and its impacts. The policy should be consistent and equitable for all regions, population groups, and economic sectors and consistent with the goals...

2016
Muna Maryam Azmy Mazlan Hashim Shinya Numata Tetsuro Hosaka Nur Supardi Md. Noor Christine Fletcher

General flowering (GF) is a unique phenomenon wherein, at irregular intervals, taxonomically diverse trees in Southeast Asian dipterocarp forests synchronize their reproduction at the community level. Triggers of GF, including drought and low minimum temperatures a few months previously has been limitedly observed across large regional scales due to lack of meteorological stations. Here, we aim...

Journal: Desert 2007
H. Mohammadi, M. Karimpour Reihan

Abstract This research investigates the effect of drought on ground water table of Neishabour plain. The precipitation data of Nishabour synoptic station during 1990-2001, the Bar climatology station during 1964-2001 and the data of hydrometric stations of Kherv and Bar in 1996-2001 have been used as the base of analysis. The method of Herbest et all has been used to analyze the drought. Usin...

2011
G. Ren X. K. Zou Y. Q. Zhou Y. Y. Ren Y. Jiang F. M. Ren Q. Zhang X. L. Wang L. Zhang

An Integrated Extreme Climatic Index (IECI) is defined for analyzing the overall trend of change in the frequencies of major extreme climatic events over mainland China. The index is composed of 7 individual extreme indicators, i.e. the country-averaged frequencies of high temperature, low temperature, intense precipitation, dust storm and strong wind events, meteorological drought area percent...

2010
Sylvain Dubey Richard Shine

Aim Although climatic fluctuations occurred world-wide during the Pleistocene, the severity of glacial and drought events – and hence their influence on animal and plant biogeography – differed among regions. Many Holarctic species were forced to warmer-climate refugia during glacial periods, leaving the genetic signature of recent expansion and gene flow among modern-day populations. Montane s...

2015
Lina Zhao Tao Pei Gege Yang Chenghu Zhou Yongfeng Zhou

Climate is one of the most important factors determining the adaptive evolution of plants. In this study, 44 different populations of wild barley were used as materials to analyze the diversity of 17 genes (495 sequences), in order to study the influence of different climatic conditions on adaptive evolution of wild barley. A Geographical Information System (GIS) provided tools to visually pres...

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