Contribution of the Patagonia Icefields of South America to sea level rise

Digital elevation models of the Northern and Southern Patagonia Icefields of South America generated from the 2000 Shuttle Radar Topography Mission were compared with earlier cartography to estimate the volume change of the largest 63 glaciers. During the period 1968/1975-2000, these glaciers lost ice at a rate equivalent to a sea level rise of 0.042 +/- 0.002 millimeters per year. In the more recent years 1995-2000, average ice thinning rates have more than doubled to an equivalent sea level rise of 0.105 +/- 0.011 millimeters per year. The glaciers are thinning more quickly than can be explained by warmer air temperatures and decreased precipitation, and their contribution to sea level per unit area is larger than that of Alaska glaciers.     

Cenozoic plant diversity in the neotropics

Several mechanisms have been proposed to explain the high levels of plant diversity in the Neotropics today, but little is known about diversification patterns of Neotropical floras through geological time. Here, we present the longest time series compiled for palynological plant diversity of the Neotropics (15 stratigraphic sections, 1530 samples, 1411 morphospecies, and 287,736 occurrences) from the Paleocene to the early Miocene (65 to 20 million years ago) in central Colombia and western Venezuela. The record shows a low-diversity Paleocene flora, a significantly more diverse early to middle Eocene flora exceeding Holocene levels, and a decline in diversity at the end of the Eocene and early Oligocene. A good correlation between diversity fluctuations and changes in global temperature was found, suggesting that tropical climate change may be directly driving the observed diversity pattern. Alternatively, the good correspondence may result from the control that climate exerts on the area available for tropical plants to grow.     

南美洲安第斯山块茎美洲落葵引种评价

美洲落葵为南美安第斯地区的一类块茎作物,以从国际马铃薯中心引进7个生态型的试管苗为试验材料,通过组培快繁形成一定的栽种.在此基础上,通过在昆明的大棚品种栽培比较,在昆明、石林、丽江三地的露地栽培对比以及在丽江的大棚、露地栽培对比,选择出在云南大棚栽培及露地栽培的适应品种(生态型),结果表明U5、U7较适合大棚栽培,U5、U6、U7较适合露地栽培.试验结果还表明,不同地区的栽培对植物生长及产量有影响,但对美洲落葵的营养成分几乎没有影响.     

A 3620-Year Temperature Record from Fitzroya cupressoides Tree Rings in Southern South America

A tree-ring width chronology of alerce trees (Fitzroya cupressoides) from southern Chile was used to produce an annually resolved 3622-year reconstruction of departures from mean summer temperatures (December to March) for southern South America. The longest interval with above-average temperatures was from 80 B.C. to A.D. 160. Long intervals with below-average temperatures were recorded from A.D. 300 to 470 and from A.D. 1490 to 1700. Neither this proxy temperature record nor instrumental data for southern South America for latitudes between 35 degrees and 44 degrees S provide evidence of a warming trend during the last decades of this century that could be related to anthropogenic causes. The data also indicate that alerce is the second longest living tree after the bristlecone pine (Pinus Iongaeva).     

Biosynthesis of plant volatiles: nature's diversity and ingenuity

Plant volatiles (PVs) are lipophilic molecules with high vapor pressure that serve various ecological roles. The synthesis of PVs involves the removal of hydrophilic moieties and oxidation/hydroxylation, reduction, methylation, and acylation reactions. Some PV biosynthetic enzymes produce multiple products from a single substrate or act on multiple substrates. Genes for PV biosynthesis evolve by duplication of genes that direct other aspects of plant metabolism; these duplicated genes then diverge from each other over time. Changes in the preferred substrate or resultant product of PV enzymes may occur through minimal changes of critical residues. Convergent evolution is often responsible for the ability of distally related species to synthesize the same volatile.     

Montmorillonite-Vermiculite Interstratification in Clays from Eocene Chalk Soils

Soils of the Eocene chalk often show interstratification in their clay fractions, though discrete 14- and 18-A spacings are the rule rather than the exception. It is also frequent that a 16-A intermediate shows in place of these diffraction maxima. This intermediate is indicative of complex interstratification. It is a unique feature of this body of soils and a strong indication that existing data on random and regular interstratification are both correct and diagnostic. The rare but interesting diffuse spacings spacings which are observed at 22 A are another unusual feature of the clays of this group of soils.     

New evidence for the antiquity of man in North America deduced from aspartic acid racemization

Ages of several Californzia Paleo-Indlian skeletons have been deduced from the extent of aspartic acid racemization. These dates suggest that man was present in North America at least 50,000 years before the present.     

Determinants of adoption and adoption intensity of precision agriculture technologies: evidence from South Dakota

Precision Agriculture - Precision agriculture technologies (PATs) are promoted as part of both economically efficient and environmentally sustainable agriculture practices. Available PATs are...     

太原市城区绿地植物物种多样性研究

【目的】调查太原市城区绿地植物物种的多样性,为太原市城市绿地的规划建设和植物物种多样性的保护与利用提供科学依据。【方法】采用群落生态学的调查方法,调查太原城区绿地植物的组成、构成要素及垂直结构等,运用重要值、丰富度指数、均匀度指数和Shannon-Wiener指数综合评价绿地植物的物种多样性。【结果】太原城区绿地共有维管束植物83科243属402种,主要分布在蔷薇科、菊科、豆科及杨柳科,且以引进种略多于本地种,栽培植物种类远多于野生植物种类;垂直结构以乔灌草型和乔草型居多,二者的丰富度指数、均匀度指数及Shannon-Wiener指数较高;不同功能绿地中,森林公园、附属绿地、龙潭公园和玉门河公园的植物物种多样性指数均较高。【结论】太原城区绿地植物物种多样性水平一般,需加大力度丰富和保护植物物种多样性。     

植物多样性对丛枝菌根真菌多样性的影响研究进展

丛枝菌根真菌(arbuscular mycorrhizal fungi(AMF))的多样性是生物多样性的重要组成部分,它对整个生态系统的进化发展起着重要作用.结合宿主植物与丛枝菌根真菌的相互关系,综述近年来植物多样性对丛枝菌根真菌物种、菌根结构、菌丝侵染率、孢子密度及分子遗传力的影响的研究.     

南美洲和非洲的农业资源及其开发

随着我国经济的快速发展,城市化进程将更进一步,相应的耕地面积也将减少,如何保障我国粮食安全成为一个应长期关注的问题。通过分析南美洲和非洲的土地资源、人力资源、水资源及相关政策,提出了发展海外农业的新观点及建议。     

A 5-micron-bright spot on Titan: evidence for surface diversity

Observations from the Cassini Visual and Infrared Mapping Spectrometer show an anomalously bright spot on Titan located at 80 degrees W and 20 degrees S. This area is bright in reflected light at all observed wavelengths, but is most noticeable at 5 microns. The spot is associated with a surface albedo feature identified in images taken by the Cassini Imaging Science Subsystem. We discuss various hypotheses about the source of the spot, reaching the conclusion that the spot is probably due to variation in surface composition, perhaps associated with recent geophysical phenomena.     

AFHVS 2016 presidential address: Decoding diversity in the food system: wheat and bread in North America

Diversity is important for the resilience of food systems, as well as for its own sake. Just how diverse are the systems that produce our food? I explore this question with a focus on wheat and bread and North America, and even more specifically in baking, milling and farming. Although the opacity of food and agricultural systems makes definitive answers difficult, these segments appear to be increasingly uniform with respect to ownership, geography, varieties and genes. There are also important countertrends, and while efforts to resist uniformity are currently small, they are making some progress in maintaining or even increasing diversity in some areas.     

陇山山地自然区药用植物资源及多样性研究

【目的】了解陇山山地自然区药用植物资源及其分布规律,分析该区药用植物多样性特征,为该区药用植物资源的开发利用和保护提供科学依据。【方法】结合第四次全国中药资源普查工作,通过野外调查,统计陇山山地自然区药用植物种类构成及其科、属、种层面的具体分布,分析其分布类型、濒危物种和道地、特色药材现状,并对其生长类型、药用部位进行分类统计,分析当地药用植物利用现状及问题并提出对策。【结果】陇山山地自然区共有药用植物146科、763属、1 838种,其中珍稀濒危药用植物45种,道地药材103种,特色药材144种,多年生草本类药材943种,以全草类、根类和根茎类入药的药材较多。区内药用植物属存在15种分布区类型18个变型,药用植物区系热带、温带性质显著,同时具有一定的古老成分。【结论】陇山山地自然区药用植物种类丰富,多样性程度较高,应加强资源保护工作,科学合理地开发利用该区药用植物资源。     

Origin of whales from early artiodactyls: hands and feet of Eocene Protocetidae from Pakistan

Partial skeletons of two new fossil whales, Artiocetus clavis and Rodhocetus balochistanensis, are among the oldest known protocetid archaeocetes. These came from early Lutetian age (47 million years ago) strata in eastern Balochistan Province, Pakistan. Both have an astragalus and cuboid in the ankle with characteristics diagnostic of artiodactyls; R. balochistanensis has virtually complete fore- and hind limbs. The new skeletons are important in augmenting the diversity of early Protocetidae, clarifying that Cetacea evolved from early Artiodactyla rather than Mesonychia and showing how early protocetids swam.     

日光温室荷兰布利塔茄子高产栽培技术

根据荷兰布利塔茄子新品种的特征特性和日光温室冬春茬栽培表现,本文详细总结了荷兰布利塔茄子日光温室春茬模式化高产、高效栽培技术,为其他同类地区日光温室栽培该品种提供了技术依据。     

Forecasting fire season severity in South America using sea surface temperature anomalies

Fires in South America cause forest degradation and contribute to carbon emissions associated with land use change. We investigated the relationship between year-to-year changes in fire activity in South America and sea surface temperatures. We found that the Oceanic Ni?o Index was correlated with interannual fire activity in the eastern Amazon, whereas the Atlantic Multidecadal Oscillation index was more closely linked with fires in the southern and southwestern Amazon. Combining these two climate indices, we developed an empirical model to forecast regional fire season severity with lead times of 3 to 5 months. Our approach may contribute to the development of an early warning system for anticipating the vulnerability of Amazon forests to fires, thus enabling more effective management with benefits for climate and air quality.