检索结果-南通市图书馆

Stand history is more important than climate in controlling red maple (Acer rubrum L.) growth at its northern distribution limit in western Quebec, Canada

引用

Journal of Plant Ecology 2015年第4期8卷 368-379页

作者： Yun Zhang Yves Bergeron Xiu-Hai Zhao igor Drobyshev Institut de recherche sur les forêts Universitédu Québec en Abitibi-Témiscamingue(UQAT)445 boul.de l’UniversitéRouyn-NorandaQuébec J9X 5E4Canada Key Laboratory for Forest Resources&Ecosystem Processes of Beijing Beijing Forestry UniversityBeijing 100083P.R.China Swedish University of Agricultural Sciences Southern Swedish Forest Research CentrePO Box 49Alnarp SE-23053Sweden Present address:National Plateau Wetlands Research Center Southwest Forestry UniversityKunming 650224P.R.China.

Aims We examined growth of red maple(Acer rubrum l.)to evaluate environmental controls of its northern distributional limit in Eastern North america and its potential response to future climate *** We collected growth data from nine sites located along a 300-km transect(47-49°N),which included frontier population of red maple and covered three bioclimatic domains in western *** ana-lyzed three growth variables:growth rates during the first 30 years of maple lifespan,cumulative basal area increment(ba I)over the most recent decade(2000-2009)and annual growth rate over the whole tree lifespan ranging from 58 to 112 *** also examined growth sensitivity to climate by using response function *** Findingsthree different proxies of maple absolute growth(initial growth rate,ba I during 2000-09 and mean diameter growth rate)indicated a better growth with an increase in *** speculate that stand history effectively overrode the direct effects of colder climate on maple growth along the s-N *** of maple in the southern sites likely occurred in canopy gaps,whereas in the north it was contingent upon large disturbances such as stand-replacing fires,which apparently provided more favorable light environment for maple growth than canopy *** annual growth variability,which reflects effects of annual weather on growth and is largely independent from the absolute growth rate,was significantly affected by monthly climate,suggesting a positive effect of higher summer temperature in the northern part of the transect(48-49°N)and a negative effect of summer drought in the south(47-48°N).In the future,the natural and human disturbance regimes will be dominant controls of the actual biomass productivity of red maple at the northern limit of its present distribution *** effects of climate on maple growth would likely be less important in this context,and will likely entail negative effect of increased summer drought

关键词： biomass productivity climate change dendrochronology ecotone hardwoods species migration

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Structure and Thermoelectric Properties of Nanostructured (Bi, Sb)<sub>2</sub>Te<sub>3</sub>(Review)

引用

Advances in Materials Physics and Chemistry 2013年第2期3卷 119-132页

作者： igor A. Drabkin Vladimir V. Karataev Vladimir B. Osvenski Aleksandr I. Sorokin Gennady I. Pivovarov Natalie Yu. Tabachkova Department of dielectric and semiconductor materials National University of Science and Technology “MISIS” Moscow Russia Department of functional and structural materials Technological Institute of Superhard and New Carbon Materials Troitsk Russia Department of semiconductor materials Giredmet Ltd. Moscow Russia

The investigation of the structure and thermoelectric properties of nanostructured solid solutions (Bi, Sb)2Te3 p-type has been carried out. The samples were obtained by grinding of original compositions in a planetary ball mill and by spark plasma sintering (SPS). Initial powder has an average particle size of 10 - 12 nm according to transmission electron microscopy, and the size of the coherent scattering region (CSR) obtained by X-ray line broadening. During sintering at ts = 250°C - 400°C, the grain size and CSR increased, which was associated with the processes of recrystallization. The maximum of size distribution of CSR shifts to larger sizes when ts increases so that no broadening of X-ray lines at ts = 400°C can take place. At higher ts, the emergence of new nanograins is observed. The formation of nanograins is conditioned by reducing of quantity of the intrinsic point defects produced in the grinding of the source materials. The study of the electrical conductivity and the Hall effect in a single crystal allows to estimate the mean free path of the holes-L in the single crystal Bi0.5Sb1.5Te3 which at room temperature is 2 - 5 nm (it is much smaller than the dimensions of CSR in the samples). The method for evaluation of L in polycrystalline samples is proposed. At room temperature, L is close to the mean free path in single crystals. Scattering parameter holes in SPS samples obtained from the temperature dependence of the Seebeck coefficient are within the measurement error equal to the parameter of the scattering of holes in a single crystal. The figure of merit ZT of SPS samples as a function of composition and sintering temperature has been investigated. Maximum ZT, equal to 1.05 at room temperature, is obtained for the composition Bi0.4Sb1.6Te3 at ts = 500°C and a pressure of 50 MPa. The causes of an apparent increase in thermoelectric efficiency are discussed.

关键词： Solid Solutions (Bi Sb)2Te3 P-Type Nanostructure Spark Plasma Sintering Conductivity Hall Effect Hole Free Path Seebeck Coefficient Thermal Conductivity Figure of Merit

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：