Climatic Window Research Articles

Agronomic efficiency and economic viability of wheat crop under varied sowing environments in North Western Himalaya

The study examines the suitable climatic windows in the face of climate change under limited irrigations under sub temperate climate. The field experiment in Randomized Block Design, comprising of four dates of sowing viz., October 20, November 10, November 30 and December 20, and three genotypes viz., HPW-249, HPW-155 and HPW-42 in silty clay loam, acidic soil was conducted during Rabi session for two years at CSKHPKV, Palampur, Himachal Pradesh. The days taken to complete different phenophases were statistically at par amongst varieties, whereas DAS to vegetative stage and heading maturity were observed minimum reflecting lowest DAS for maturity in 20 th December sowing. The growth and yield attributes viz., plant height, number of tiller m -2 , number of grains tillers -1 and 1000-grain weight was highest in variety HPW-249 during both the years. Amongst sowing environments, October 20 th sown crop gave significantly highest values of growth and yield during both the years. The periodic LAI recorded similar upto 60 DAS and thereafter, the highest values were recorded in HPW-249 upto physiological maturity. Amongst sowing environments, 20th October sown gave highest LAI during entire ontogeny of crop likewise yield attributes, grain and straw yield was highest in 20 th October sown crops. Amongst variety HPW-249 gave highest grain yield to the tune of 43.0 in 2011-12 and 45.6 q/ha in 2012-13. The economic returns and benefit cost ratio were also significantly highest in HPW-249 (Rs. 75568 in 2011-12 and 81219 in 2012-13). Likewise, grain yield, net returns and B: C ratio were significantly highest in 20th October sown crop compared to subsequent dates of sowing.

Quality and Quantity Loss by Aphid Infestation in Vegetables Grown under Protected Cultivation in Ladakh Region

<p>During the hardly six months of suitable climatic window in summer season, many vegetable crops such as cabbage, cauliflower and radish are grown extensively in Ladakh region of India. These crops contribute significantly to the requirement of military and paramilitary troops in addition to the civil population inhabiting the region. In addition to growing these vegetable crops outdoor, some of these are grown under protective cultivation to get early and more produce, however various insect pests including aphids cause serious damage to the crops annually. The present study was undertaken to estimate the quality as well as quantity loss due to aphids infestation in three economically important crops namely cauliflower (B. oleracea var. botrytis), knol – khol (B. caulorapa) and radish (R. sativus) in the Indus valley of Ladakh region (J&K), in 2015. Results showed that there was 7.5 % to 27.5 % reduction in chlorophyll contents in the study crops while the overall yield in infested crops ranged from 35.4 in B. caulorapa to 41.9 % in B. oleracea var. botrytis respectively. Total chlorophyll contents were decreased statistically in radish (p = 0.0002; χ2 ≥ 17.0), whereas the overall yield loss was statistically similar among all the three vegetable crops (p = 0.6). Current study is first to analyze this kind of loss in important vegetable crops in Ladakh region of India and could be used as baseline study for planning anti-aphid strategy to protect vegetable crops in Ladakh region of India.</p>

Improved Outbreak Prediction for Common Pine Sawfly (Diprion pini L.) by Analyzing Floating ‘Climatic Windows’ as Keys for Changes in Voltinism

The biology and population dynamics of pine sawfly Diprion pini L. are extremely complex and variable. Among other factors, climatic conditions determine the potential for mass outbreaks of the species. In this paper, we investigate this influence and describe a statistical approach to identify responsible climatic variables in floating time windows, thus identifying the factors responsible for the transition from latency to outbreak events. Analyses were built upon a data base comprising outbreak events and fine-scaled climatic data for the period 2002–2016 for a model region in the state of Brandenburg, Germany. By applying Random Forest statistic classification analyses, we isolated a set of four variables. They cover precipitation, temperature, and potential evapotranspiration in distinct periods during the current and the previous year. These periods are not fixed in their position but attached to the floating phenological date of bud burst of the host species Pinus sylvestris L. The complete set of variables was able to distinguish forests likely to be defoliated from those not threatened at high probabilities (95% true-positive rate, 98% true-negative rate). The identified climatic windows offer insights into population dynamics in the study region, support adjustments in current monitoring algorithms, and indicate starting points for further investigations covering other regions or different years.

An analysis of precipitation climatology over Indian urban agglomeration

While urban areas in India are rapidly expanding, the analysis of how the precipitation regimes are changing is very limited. In the present study, an attempt has been made to explore the trends in rainfall pattern over 20 most populated urban agglomeration (cities) of India using high resolution gridded, daily rainfall product (0.25° × 0.25°) obtained from India Meteorological Department (IMD). The analysis comprised of annual and monsoonal rainfall and rainy days; 1- and 10-day annual maximum rainfall; 95 and 99 percentile extreme threshold rainfall magnitude in 30 years moving window; and number of events above 95 and 99 percentile threshold in each year during 1901–2015. The Mann-Kendall (Modified Mann-Kendall) test at 0.1 significance level to detect trends, and the Thiel-Sen’s approach to estimate % change over mean have been used. Annual and monsoonal rainfall are found to be increasing with shrinking rainy days during the same period that infers rise in heavy rainfall events. Besides, the majority of the cities show increasing trends in 1- and 10-day annual maximum rainfall, number of extreme threshold events, and magnitude of extreme threshold rainfall in 30-year moving window. The Pettitt-Mann-Whitney (PMW) test was used to detect change point year. Cities with significant change point at probability level ≥90% were selected to analyze pre- and post-change point year trend in time series. In addition, the trend in precipitation variables for multiple climatic windows of 30 years with an advancement of 5 years in each window (1901–1930, 1906–1935 …, 1986–2015) show that unlike a unique long-term trend, different climatic windows have varying trend direction over the period of time. Overall, the analysis reveals the rising trend in extreme rainfall events over majority of the cities in long term (1901–2015); however, mixed pattern of trends are observed in moving climatic windows.

Climwin: An R Toolbox for Climate Window Analysis.

When studying the impacts of climate change, there is a tendency to select climate data from a small set of arbitrary time periods or climate windows (e.g., spring temperature). However, these arbitrary windows may not encompass the strongest periods of climatic sensitivity and may lead to erroneous biological interpretations. Therefore, there is a need to consider a wider range of climate windows to better predict the impacts of future climate change. We introduce the R package climwin that provides a number of methods to test the effect of different climate windows on a chosen response variable and compare these windows to identify potential climate signals. climwin extracts the relevant data for each possible climate window and uses this data to fit a statistical model, the structure of which is chosen by the user. Models are then compared using an information criteria approach. This allows users to determine how well each window explains variation in the response variable and compare model support between windows. climwin also contains methods to detect type I and II errors, which are often a problem with this type of exploratory analysis. This article presents the statistical framework and technical details behind the climwin package and demonstrates the applicability of the method with a number of worked examples.

Phenological shifts in climatic response of secondary growth allow Juniperus sabina L. to cope with altitudinal and temporal climate variability

The long-term persistence of Mediterranean high mountain flora is challenged by global warming. Understanding plant responses to different climatic drivers along altitudinal gradients is necessary in order to predict the response of Mediterranean mountain systems to the ongoing increase in drought intensity and severity. We selected the prostrate shrub Juniperus sabina L. as a model species and explored its growth response to climatic variability over the last six decades through dendrochronological methods at four sites along a 750m altitudinal gradient. Secondary growth was maximal at lower altitudes, where growing seasons are longer. Water availability was the main factor controlling secondary growth variability along the whole gradient, although the timing and strength of climatic variables affecting growth shifted with altitude. Earlier and stronger signals were detected in lower sites, where a combination with late summer signals suggested the existence of a second growth pulse in response to longer growing seasons. J. sabina adjusted its secondary growth to the changing climatic conditions by shifting the timing of its climatic response to favorable climatic windows, with earlier responses to spring rainfall in lower sites and an expanded growing season at the highest site during the second half of the study period. Our results show that at least some Mediterranean plants can grow faster at the drier edge of their range even under intense climate pressure, indicating that the response to drought stress may be highly idiosyncratic. The plastic nature of J. sabina secondary growth combined with its role as a nurse plant in Mediterranean mountains may be key to maintaining the high diversity levels of these particular ecosystems.

Intra-annual wood density fluctuations and tree-ring width patterns are sex- and site-dependent in the dioecious conifer Juniperus thurifera L.

Sex and site conditions modulate intra- and inter-annual secondary growth and its climatic sensitivity in a dioecious Mediterranean conifer. Divergent evolutionary pressures associated with differential reproductive costs in dioecious trees may lead to sex-related variation in non-reproductive functions. Sex-related differences may be site-dependent, with different outcomes depending on environmental conditions. We explored the effects of sex and environmental conditions on the climatic control of annual secondary growth and intra-annual wood density fluctuations (IADF) of a dioecious conifer (Juniperus thurifera L.) growing in two sites with contrasting hydrological conditions under a continental Mediterranean climate. Different sex-related strategies had variable effects on relative secondary growth, with females outperforming males under more favorable hydrological conditions, and males outperforming females under water-limited conditions. Ring width and IADF formation were driven by climatic factors occurring at different temporal scales. Tree-ring growth depended on factors acting prior to the initiation of the xylogenesis and to conditions directly affecting the duration and pace of cambial activity, and ring width, therefore, integrated a complex signal of factors occurring over a relatively long period, and on an annual cycle. In contrast, IADFs responded to singular short-term events that alleviated drought and promoted cambial reactivation during the summer arrest. Female trees showed a more opportunistic water use, displayed in the stronger ring-width response to June–July conditions. Enhanced cambial sensitivity in females set a lower threshold for IADF occurrence, leading to a higher frequency of IADFs irrespective of site. Intra-annual and inter-annual female growth patterns reflect an opportunistic strategy to benefit from favorable climatic windows.

Climate windows for Polynesian voyaging to New Zealand and Easter Island.

Debate about initial human migration across the immense area of East Polynesia has focused upon seafaring technology, both of navigation and canoe capabilities, while temporal variation in sailing conditions, notably through climate change, has received less attention. One model of Polynesian voyaging observes that as tradewind easterlies are currently dominant in the central Pacific, prehistoric colonization canoes voyaging eastward to and through central East Polynesia (CEP: Society, Tuamotu, Marquesas, Gambier, Southern Cook, and Austral Islands) and to Easter Island probably had a windward capacity. Similar arguments have been applied to voyaging from CEP to New Zealand against prevailing westerlies. An alternative view is that migration required reliable off-wind sailing routes. We investigate the marine climate and potential voyaging routes during the Medieval Climate Anomaly (MCA), A.D. 800-1300, when the initial colonization of CEP and New Zealand occurred. Paleoclimate data assimilation is used to reconstruct Pacific sea level pressure and wind field patterns at bidecadal resolution during the MCA. We argue here that changing wind field patterns associated with the MCA provided conditions in which voyaging to and from the most isolated East Polynesian islands, New Zealand, and Easter Island was readily possible by off-wind sailing. The intensification and poleward expansion of the Pacific subtropical anticyclone culminating in A.D. 1140-1260 opened an anomalous climate window for off-wind sailing routes to New Zealand from the Southern Austral Islands, the Southern Cook Islands, and Tonga/Fiji Islands.

Can current moisture responses predict soil CO<sub>2</sub> efflux under altered precipitation regimes? A synthesis of manipulation experiments

Abstract. As a key component of the carbon cycle, soil CO2 efflux (SCE) is being increasingly studied to improve our mechanistic understanding of this important carbon flux. Predicting ecosystem responses to climate change often depends on extrapolation of current relationships between ecosystem processes and their climatic drivers to conditions not yet experienced by the ecosystem. This raises the question of to what extent these relationships remain unaltered beyond the current climatic window for which observations are available to constrain the relationships. Here, we evaluate whether current responses of SCE to fluctuations in soil temperature and soil water content can be used to predict SCE under altered rainfall patterns. Of the 58 experiments for which we gathered SCE data, 20 were discarded because either too few data were available or inconsistencies precluded their incorporation in the analyses. The 38 remaining experiments were used to test the hypothesis that a model parameterized with data from the control plots (using soil temperature and water content as predictor variables) could adequately predict SCE measured in the manipulated treatment. Only for 7 of these 38 experiments was this hypothesis rejected. Importantly, these were the experiments with the most reliable data sets, i.e., those providing high-frequency measurements of SCE. Regression tree analysis demonstrated that our hypothesis could be rejected only for experiments with measurement intervals of less than 11 days, and was not rejected for any of the 24 experiments with larger measurement intervals. This highlights the importance of high-frequency measurements when studying effects of altered precipitation on SCE, probably because infrequent measurement schemes have insufficient capacity to detect shifts in the climate dependencies of SCE. Hence, the most justified answer to the question of whether current moisture responses of SCE can be extrapolated to predict SCE under altered precipitation regimes is "no" – as based on the most reliable data sets available. We strongly recommend that future experiments focus more strongly on establishing response functions across a broader range of precipitation regimes and soil moisture conditions. Such experiments should make accurate measurements of water availability, should conduct high-frequency SCE measurements, and should consider both instantaneous responses and the potential legacy effects of climate extremes. This is important, because with the novel approach presented here, we demonstrated that, at least for some ecosystems, current moisture responses could not be extrapolated to predict SCE under altered rainfall conditions.

Future climate and fire interactions in the southeastern region of the United States

Fire has a profound, though paradoxical influence on landscapes of the southeastern U.S.; it simultaneously maintains native biodiversity and ecosystem processes but also threatens silvicultural resources and human landscapes. Furthermore, since the majority of the southern landscape is heavily influenced by human activities, contemporary fire regimes are human managed disturbances within extant fire-dependent ecosystems. Though there is considerable uncertainty in climate projections for the southeastern U.S., climate change will likely impact both prescribed fire and wildfire. In this review, we synthesize climate change-fire interactions, discuss the impacts of uncertainty in a human-dominated landscape, and illuminate how both climate change projections and their uncertainties might impact our ability to manage forests in the Southeast. We define the Southeast region as consisting of the Gulf Coastal Plain, Lower Atlantic Coastal Plain, Piedmont and southern Appalachians and associated subregions. This region has the greatest area burned by prescribed fire, the highest number of wildfires in the continental U.S. and contains globally significant hotspots of biodiversity, much of which is dependent on frequent fire. The use of prescribed fire as a management tool depends on a suite of weather and fuel conditions which are affected by climate. Over the next five decades, general circulation models (GCMs) consistently predict air temperature to increase by 1.5–3°C in the Southeast. Precipitation forecasts are more uncertain with respect to the mean; but, most models predict an increase in precipitation variability. Increases in the likelihood of severe droughts may increase wildfire occurrence while simultaneously limiting the implementation of prescribed burning by restricting the number of days within current prescription guidelines. While the Southeast has among the highest potential for C storage and sequestration, a reduction in C sequestration capacity due to increasing disturbances such as drought, insect infestations, hurricanes and fire, is possible. The potential for long-term shifts in forest composition from climate-altered fire regimes if coupled with an increased potential for wildfire occurrence could reduce quality and quantity of water released from forests at times when demand for high quality water will intensify for human use. Furthermore, any reduction in prescribed burning is likely to result in decreased biological diversity, particularly in the Coastal Plain, a global hotspot of biodiversity. Lastly, more future area burned by wildfire rather than prescribed fire has the potential to negatively influence regional air quality. Mitigating the negative effects of climate change-fire interactions would require actively exploiting favorable seasonal and inter-annual climate windows. Monitoring the type conversions of agricultural and fiber production forest will be critical for long-term projections of fire risk and watershed impacts of altered fire regimes.

The genetic impact of the lake chad basin population in North Africa as documented by mitochondrial diversity and internal variation of the L3e5 haplogroup.

The presence of sub-Saharan L-type mtDNA sequences in North Africa has traditionally been explained by the recent slave trade. However, gene flow between sub-Saharan and northern African populations would also have been made possible earlier through the greening of the Sahara resulting from Early Holocene climatic improvement. In this article, we examine human dispersals across the Sahara through the analysis of the sub-Saharan mtDNA haplogroup L3e5, which is not only commonly found in the Lake Chad Basin (∼17%), but which also attains nonnegligible frequencies (∼10%) in some Northwestern African populations. Age estimates point to its origin ∼10 ka, probably directly in the Lake Chad Basin, where the clade occurs across linguistic boundaries. The virtual absence of this specific haplogroup in Daza from Northern Chad and all West African populations suggests that its migration took place elsewhere, perhaps through Northern Niger. Interestingly, independent confirmation of Early Holocene contacts between North Africa and the Lake Chad Basin have been provided by craniofacial data from Central Niger, supporting our suggestion that the Early Holocene offered a suitable climatic window for genetic exchanges between North and sub-Saharan Africa. In view of its younger founder age in North Africa, the discontinuous distribution of L3e5 was probably caused by the Middle Holocene re-expansion of the Sahara desert, disrupting the clade's original continuous spread.

Research on Climate Adaptability of Energy Conservation Building with Renewable Energy Sources in Hot-Summer and Cold-Winter Zone of China

Nowadays, exploiting of renewable energy resources has become an important research field, and it has been paid great attention to all over the world. This paper takes an energy saving renovation engineering of Huazhong University of Science and Technology (HUST) in Wuhan, Hubei province, as a case, and some energy-saving technical measures were put forward, such as Active Dynamic Ventilated Envelope (ADVW), climatic adaptive windows, underground cooling and heat sources, solar building integrated system and under floor air supply system, etc. In order to realize energy saving, land saving, water saving, material saving, environmental protection and reducing pollution, this building makes the best of renewable energy resources in order to realize low energy consumption, and the technical reference was provided for promoting application of renewable energy and building energy efficiency in hot-summer and cold-winter zone of China.

Climate change and the formation of nickel laterite deposits

One of the major controls on nickel laterite deposit formation is climate. A comparison of climatic data for regions where ultramafic rocks are exposed shows that areas currently conducive to nickel laterite formation receive >1000 mm/yr precipitation, have cold month mean (CMM) temperatures between 15 and 27 °C, and warm month mean (WMM) temperatures between 22 and 31 °C. Using a compilation of paleoclimatic data and the defined climatic window of nickel laterite deposit formation allows an assessment of the timing and duration of paleo–nickel laterite formation in ancient terrains. To illustrate the potential of this technique, we show that the formation of the Caldag nickel laterite deposit of western Turkey most likely initiated when the ultramafic protolith of Cretaceous age was exposed in the Early Eocene, and that the majority of the deposit formed during the Eocene. In contrast, the formation of the Bitincke deposit, south Albania, was mostly complete by the Early Eocene, after which CMM temperatures dropped below the optimum for laterite formation.

Chasing the queens of the alien predator of honeybees: A water drop in the invasiveness ocean

The Yellow-legged hornet, Vespa velutina , was accidentally introduced in France in 2004, and then spread rapidly through the French territory but also to adjacent European countries (Spain, Portugal, and Belgium). During summer and autumn, V. velutina workers hunt domestic honeybees, Apis mellifera, for feeding their larvae. The impact of this alien species is mainly economic, beekeepers experiencing heavy colony losses, but also ecological, V. velutina hunting other pollinators. In their year-round life cycle, nest initiation by single queen during spring is the critical stage. In invaded areas, spring queen trapping using food baits has been promoted by apicultural unions in order to limit V. velutina population expansion. The goals of this work were 1) to evaluate the yield of this method, 2) to identify appropriate sites for trapping, 3) to identify potential optimal climatic windows of capture, and 4) to quantify the impact on local entomofauna. Our results showed that water proximity enhances trapping but not beehives proximity, and that trapping is inefficient if average week temperatures are below 10°C. Although the trapping effect on biodiversity should be studied more carefully, spring queen trapping is highly questionable unless specific attractants could be proposed.

Parâmetros fitotécnicos e condições microclimáticas para videira vinífera conduzida sob dupla poda sequencial

A qualidade do vinho depende da qualidade da uva produzida. As condições microclimáticas incidentes no período de crescimento e desenvolvimento da videira, especialmente na fase do estabelecimento do fruto até a colheita, afetam a qualidade do fruto. A dinâmica da água no solo tem papel importante sobre a qualidade do mosto produzido à vinificação. Em São Paulo, nas bacias de maior concentração atual da vitivinicultura ocorre um período chuvoso que se estende de novembro a fevereiro, que alcança grande parte das variedades da região em fase de crescimento e maturação da baga, o que afeta negativamente a qualidade da uva e do vinho, na maioria das safras. Por outro lado, nas mesmas regiões ocorre um período mais favorável, que é o outono/inverno com potencial de soma térmica promissor para o crescimento da videira e com incidência de um longo período de baixa pluviometria, que vai de abril a outubro. Um experimento foi conduzido, objetivando estudar o cultivo da videira nas duas estações microclimáticas descritas. Avaliou-se a composição físico-química do fruto e a condições microclimáticas para maturação da baga da videira, de 2008 a 2010. Os resultados mostraram que as variedades de videira estudas desenvolveram maior potencial de qualidade da baga, quando cultivada no período de outono-inverno, sendo o efeito mais marcante sobre Vitis vinifera.

Identifying the Critical Climatic Time Window That Affects Trait Expression

Identifying the critical time window during which climatic drivers affect the expression of phenological, behavioral, and demographic traits is crucial for predicting the impact of climate change on trait and population dynamics. Two widely used associative methods exist to identify critical climatic periods: sliding-window models and recursive operators in which the memory of past weather fades over time. Both approaches have different strong points, which we combine here into a single method. Our method uses flexible functions to differentially weight past weather, which can reflect competing hypotheses about time lags and the relative importance of recent and past weather for trait expression. Using a 22-year data set, we illustrate that the climatic window identified by our new method explains more of the phenological variation in a sexually selected trait than existing approaches. Our new method thus helps to better identify the critical time window and the causes of trait response to environmental variability.

Competition with Egyptian Geese Alopochen aegyptiaca overrides environmental factors in determining productivity of Black Sparrowhawks Accipiter melanoleucus

We studied a population of Black Sparrowhawks Accipiter melanoleucus that has recently colonized the Cape Peninsula, South Africa. Black Sparrowhawks are winter breeders: over most of their range winters are dry, but the Cape Peninsula has a Mediterranean climate, with most rain falling in winter. The birds bred at an average density of 38 pairs/100 km2. Monitoring of 70 breeding attempts by 26 pairs showed that the birds favoured large stands of trees for breeding. Birds breeding in smaller stands were more randomly spaced, dispersion being determined by habitat availability. Parameters related to climate, habitat and aspects of nest‐site selection failed to predict the birds’ productivity despite the fact that they had recently colonized a novel climatic window. Rather, productivity was best explained by the probability of nest usurpation by highly aggressive Egyptian Geese Alopochen aegyptiaca. Pairs encountering Goose usurpation problems raised an average of 0.76 chicks per breeding attempt, compared with 1.58 chicks for pairs without Geese. The only defence against nest usurpation by Geese appears to be the construction of multiple nests, an option most available to and most exploited by birds breeding in large stands of trees.

Desert speleothems reveal climatic window for African exodus of early modern humans

Research Article| September 01, 2007 Desert speleothems reveal climatic window for African exodus of early modern humans Anton Vaks; Anton Vaks 1Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel, and Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem 95501, Israel Search for other works by this author on: GSW Google Scholar Miryam Bar-Matthews; Miryam Bar-Matthews 2Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem 95501, Israel Search for other works by this author on: GSW Google Scholar Avner Ayalon; Avner Ayalon 2Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem 95501, Israel Search for other works by this author on: GSW Google Scholar Alan Matthews; Alan Matthews 3Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel Search for other works by this author on: GSW Google Scholar Ludwik Halicz; Ludwik Halicz 4Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem 95501, Israel Search for other works by this author on: GSW Google Scholar Amos Frumkin Amos Frumkin 5Department of Geography, Hebrew University of Jerusalem, Jerusalem 91905, Israel Search for other works by this author on: GSW Google Scholar Author and Article Information Anton Vaks 1Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel, and Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem 95501, Israel Miryam Bar-Matthews 2Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem 95501, Israel Avner Ayalon 2Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem 95501, Israel Alan Matthews 3Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel Ludwik Halicz 4Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem 95501, Israel Amos Frumkin 5Department of Geography, Hebrew University of Jerusalem, Jerusalem 91905, Israel Publisher: Geological Society of America Received: 12 Feb 2007 Revision Received: 30 Apr 2007 Accepted: 02 May 2007 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 The Geological Society of America, Inc. Geology (2007) 35 (9): 831–834. https://doi.org/10.1130/G23794A.1 Article history Received: 12 Feb 2007 Revision Received: 30 Apr 2007 Accepted: 02 May 2007 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Anton Vaks, Miryam Bar-Matthews, Avner Ayalon, Alan Matthews, Ludwik Halicz, Amos Frumkin; Desert speleothems reveal climatic window for African exodus of early modern humans. Geology 2007;; 35 (9): 831–834. doi: https://doi.org/10.1130/G23794A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract One of the first movements of early modern humans out of Africa occurred 130–100 thousand years ago (ka), when they migrated northward to the Levant region. The climatic conditions that accompanied this migration are still under debate. Using high-precision multicollector–inductively coupled plasma–mass spectrometry (MC-ICP-MS) U-Th methods, we dated carbonate cave deposits (speleothems) from the central and southern Negev Desert of Israel, located at the northeastern margin of the Saharan-Arabian Desert. Speleothems grow only when rainwater enters the unsaturated zone, and this study reveals that a major cluster of wet episodes (the last recorded in the area) occurred between 140 and 110 ka. This episodic wet period coincided with increased monsoonal precipitation in the southern parts of the Saharan-Arabian Desert. The disappearance at this time of the desert barrier between central Africa and the Levant, and particularly in the Sinai-Negev land bridge between Africa and Asia, would have created a climatic “window” for early modern human dispersion to the Levant. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Warmings in the far northwestern Pacific promoted pre-Clovis immigration to America during Heinrich event 1

Research Article| March 01, 2006 Warmings in the far northwestern Pacific promoted pre-Clovis immigration to America during Heinrich event 1 Michael Sarnthein; Michael Sarnthein 1Institute for Geosciences, University of Kiel, Olshausenstrasse 40, 24118 Kiel, Germany Search for other works by this author on: GSW Google Scholar Thorsten Kiefer; Thorsten Kiefer 2Institute for Geosciences, University of Kiel, Olshausenstrasse 40, 24118 Kiel, Germany, and Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK Search for other works by this author on: GSW Google Scholar Pieter M. Grootes; Pieter M. Grootes 3Leibniz Labor, University of Kiel, Max-Eyth Strasse 11, 24118 Kiel, Germany Search for other works by this author on: GSW Google Scholar Henry Elderfield; Henry Elderfield 4Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK Search for other works by this author on: GSW Google Scholar Helmut Erlenkeuser Helmut Erlenkeuser 5Leibniz Labor, University of Kiel, Max-Eyth Strasse 11, 24118 Kiel, Germany Search for other works by this author on: GSW Google Scholar Author and Article Information Michael Sarnthein 1Institute for Geosciences, University of Kiel, Olshausenstrasse 40, 24118 Kiel, Germany Thorsten Kiefer 2Institute for Geosciences, University of Kiel, Olshausenstrasse 40, 24118 Kiel, Germany, and Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK Pieter M. Grootes 3Leibniz Labor, University of Kiel, Max-Eyth Strasse 11, 24118 Kiel, Germany Henry Elderfield 4Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK Helmut Erlenkeuser 5Leibniz Labor, University of Kiel, Max-Eyth Strasse 11, 24118 Kiel, Germany Publisher: Geological Society of America Received: 16 Sep 2005 Revision Received: 03 Nov 2005 Accepted: 05 Nov 2005 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2006) 34 (3): 141–144. https://doi.org/10.1130/G22200.1 Article history Received: 16 Sep 2005 Revision Received: 03 Nov 2005 Accepted: 05 Nov 2005 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Michael Sarnthein, Thorsten Kiefer, Pieter M. Grootes, Henry Elderfield, Helmut Erlenkeuser; Warmings in the far northwestern Pacific promoted pre-Clovis immigration to America during Heinrich event 1. Geology 2006;; 34 (3): 141–144. doi: https://doi.org/10.1130/G22200.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Well-dated multidecadal- to centennial-scale sediment records from the subarctic northwest Pacific show that the early deglacial 18.5–15.0 ka was marked by 3 pronounced short-term warmings of ∼5 °C. They lasted 500–1500 yr each and were coeval with early to late stages of cold Heinrich event 1 in the North Atlantic. These regional climate windows may have promoted a pre-Clovis emigration of people from the cold-arid monsoon climate in East Asia to the climatically more favorable, then-emerged Beringian and Aleutian shelf regions and the Americas, as suggested by archeological findings. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Role of topography in facilitating coexistence of trees and grasses within savannas

The factors and processes that may explain the observed coexistence of trees and grasses in savannas are not well understood. Here we propose a new hypothesis that addresses this issue. We hypothesize that “variations in elevation at relatively short horizontal scales of ∼1 km force similar variations in soil moisture and thus create significantly different hydrologic niches within any large area. Under water‐limited conditions the relatively wet valleys favor trees, while the relatively dry hills favor grasses. This coexistence of trees and grasses is only possible for a window of climatic conditions that are characteristic of savannas.” To test this hypothesis, numerical simulations are performed for the region of West Africa using a model that simulates vegetation dynamics, the Integrated Biosphere Simulator (IBIS), and a distributed hydrologic model, Systeme Hydrologique Europeen (SHE). IBIS is modified to include the groundwater table (GWT) as a lower boundary. The spatial distribution of GWT is simulated by SHE. At 9°N the model simulates trees even when the GWT is assumed to be infinitely deep; at 13°N the model simulates grasses even when the capillary fringe of the GWT reaches the surface. However, for the transitional climate, at 11°N, trees are simulated when the GWT is at ∼2.5 m from the surface, but grasses are simulated when the GWT is deeper than 2.5 m. These results suggest that the variability of soil moisture forced by topography can be a determinant factor of vegetation distribution within savannas. Furthermore, they confirm that this role of topography can be significant only in a certain climatic window characteristic of savannas.