DOCSLIB.ORG

Drought Tolerant Corn Report

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Drought Tolerant Corn Report High and Dry Why Genetic Engineering Is Not Solving Agriculture’s Drought Problem in a Thirsty World ii High and Dry Why Genetic Engineering Is Not Solving Agriculture’s Drought Problem in a Thirsty World Doug Gurian-Sherman June 2012 © 2012 Union of Concerned Scientists All rights reserved Doug Gurian-Sherman is a senior scientist in the Food and Environment Program of the Union of Concerned Scientists. The Union of Concerned Scientists (UCS) is the leading science-based nonprofit working for a healthy environment and a safer world. UCS combines independent scientific research and citizen action to develop innovative, practical solutions and secure responsible changes in government policy, corporate practices, and consumer choices. The goal of the UCS Food and Environment Program is a food system that encourages innovative and environmentally sustainable ways to produce high-quality, safe, and affordable food while ensuring that citizens have a voice in how their food is grown. More information is available on the UCS website at www.ucsusa.org/food_and_agriculture. This report is available on the UCS website (www.ucsusa.org/publications) or may be obtained from: UCS Publications 2 Brattle Square Cambridge, MA 02238-9105 Or, email [email protected] or call (617) 547-5552. Cover photo: © iStockphoto.com/Drbouz ii Contents Figures iii Acknowledgments iv Executive Summary 1 Chapter 1. Introduction 6 Roadmap to the Report 6 Chapter 2. The Complexity of Drought and Efforts to Address It 7 Major Approaches to Reducing the Impact of Drought 8 The Challenges of Measuring Drought and Comparing Drought Tolerance 11 Drought Tolerance and Water-Use Efficiency 12 Summary: The Complexity of Drought and Solutions to It 12 Chapter 3. The Pipeline of Drought-Tolerant GE Crops 14 U.S. Field Trials of GE Drought-Tolerant Crops 14 Monsanto’s Drought-Tolerant Corn: The Bacterial Cold-Shock Gene 17 Summary: Monsanto’s cspB Corn and the GE Drought-Tolerance Pipeline 20 Chapter 4. Prospects for GE Drought-Tolerant Crops 22 Can Genetic Engineering Based on Single Genes Succeed? 22 Using Drought-Tolerance Genes from Plants 23 Costs, Markets, and the Time Required to Develop GE Crops 24 Chapter 5. Conclusions and Recommendations 26 Recommendations 27 References 29 Figures Figure 1. Genetic Diversity among Plants That Can Be Used in Wheat Breeding 8 Figure 2. USDA-Approved Field Trials of GE Drought-Tolerant Crops, 15 1998–2010 Figure 3. Top Five Crops in Field Trials of GE Drought-Tolerant Varieties 16 iii Acknowledgments This report is dedicated to my partner and spouse, Stacey, and my daughter, Shoshana. Without their unwavering support and encouragement, this report would not have been possible. This report was made possible in part through the generous support of the C.S. Fund, the Clif Bar Family Foundation, the Cornerstone Campaign, the David B. Gold Foundation, the Deer Creek Foundation, the Tomchin Family Charitable Foundation, and UCS members. For their thoughtful reviews of the report, the author would like to thank Major Goodman, North Carolina State University; Frank Kutka, North Dakota State University, and Seth Murray, Texas A&M University. The time entailed in reviewing a report of this length is considerable, and their comments and suggestions greatly improved it. At UCS, the author thanks Jane Rissler, who provided two of the figures, scientific literature searches, and most of the USDA field trial data. The author also thanks Margaret Mellon and Kathy Rest for their reviews of the report, Erika Spanger-Siegfried and Nadia Madden for their comments on the executive summary, and Heather Sisan for general assistance. Karen Perry-Stillerman’s editing of the executive summary, and her managerial efforts to keep the report on track, were invaluable. The advice, encouragement, and helpful edits of these colleagues influenced and improved the report’s final form. We would also like to thank Sandra Hackman for careful and precise copyediting, and Rob Catalano for his design and layout of the executive summary. The opinions and information in this report are the sole responsibility of the author, and do not necessarily reflect the opinions of the foundations that supported it or the individuals who reviewed and commented on it. iv Executive Summary Droughts—periods of abnormally dry weather—can be devastating to farmers and food production. The historic Texas drought of 2011 caused a record $5.2 billion in agricultural losses, for example, making it the most costly drought on record. Similar crippling droughts have recently occurred around the world, and climate scientists expect the frequency and severity of droughts to increase, sometimes unpredictably, in some regions as the global climate heats up. Although extreme droughts receive the most attention, mild to moderate droughts actually affect more acreage, and also cause substantial crop losses. Agriculture accounts for the lion’s share of all water extracted from rivers and wells—about 70 percent—setting up conflicts between food production and other uses. And beyond competition for water among various human needs are the requirements of aquatic organisms, such as game fish prized by sportspeople, who bring dollars to local economies. Finding ways to protect food production and farmers’ livelihoods from devastation by drought—and also to reduce agriculture’s need for water—is therefore vital. The Union of Concerned Scientists (UCS) analyzed the prospects for improving crops in ways that can reduce water use overall, and losses during dry periods. We focused on crop genetic engineering—the lab-based manipulation of genes from any source to alter plants. Practitioners and proponents have touted the potential of genetic engineering to address drought. Biotech companies, including Monsanto, have promised to deliver new crop varieties engineered with novel genes that enable them to thrive under drought conditions. The biotech industry has also suggested that genetic engineering can reduce demand for water from crops even under normal conditions—resulting in “more crop per drop.” However, we found little evidence of progress in making crops more water efficient. We also found that the overall prospects for genetic engineering to significantly address agriculture’s drought and water-use challenges are modest at best. Genetic Engineering Offers Modest Results…at High Cost The biotech industry has so far received regulatory approval—in December 2011—for only one crop engineered for drought tolerance. Available data show that Monsanto’s so-called DroughtGard corn produces only modest results. And according to data supplied by Monsanto and analysis by the U.S. Department of Agriculture (USDA), the variety does so under only moderate drought conditions. In fact, despite what the industry may have hoped, this product—and this technology—are not a panacea for drought. Drought presents a particular challenge for genetic engineering because it can take many forms. Droughts vary in their severity and their timing in relation to crop growth. Related factors such as soil quality affect the ability of crops to withstand drought. These complications make it unlikely that any single approach or gene used to make a genetically engineered (GE) crop will be useful in all—or even most—types of drought. What’s more, many genes control drought tolerance in plants—a particular challenge for genetic engineering, which so far can manipulate only a few genes at a time. 1 Evidence is also scant that the technology will help crops and farmers use water more efficiently in the foreseeable future. Very few experimental GE crops have been designed to use water more efficiently, and none are approaching commercialization. In an era of reduced government spending, the cost-effectiveness of different technologies for improving agriculture—often supported by public research funding—is important. We found that although genetic engineering is beginning to have some success in enhancing the drought tolerance of crops such as corn, other technologies, such as classical and newer forms of breeding, continue to be more effective, at lower cost. Improved farming practices are also likely to be more effective in enhancing the ability of crops to withstand drought. Crop management practices complement genetic approaches such as breeding and genetic engineering, and should receive more public support in the form of government research and incentives. An excessive focus on genetic engineering at the expense of other approaches risks leaving farmers and the public high and dry when it comes to ensuring that the United States and other nations can produce enough food, and have enough clean freshwater, to meet everyone’s needs. Major Findings To produce this report, we analyzed scientific studies on GE drought tolerance and crop breeding, and the USDA’s database on field trials of drought-tolerant GE crops. We also reviewed Monsanto’s 2009 petition for approval of DroughtGard, and the USDA’s environmental assessment based on that petition. These sources showed that scientists engineered several types of genes, mostly from plants, for drought tolerance in the late 1990s and early 2000s. By the middle of that decade, researchers were using drought-specific gene switches, called promoters, to control when and how strongly the engineered genes are turned on. Other findings: • The annual number of USDA-regulated field trials of crops engineered for drought tolerance remained below 20 from 1998 to 2003. That number spiked to 82 in 2005, and remained between 82 and 113 for seven years, including 90 trials as of late 2011. • Developing a new GE trait typically takes about 10 to 15 years, including several years prior to field trials. Given the surge in field trials beginning in 2005, several drought-tolerance genes should be nearing approval and commercialization, if these crops have proved effective and reliable in field trials. However, as noted, the USDA has approved only one GE drought- tolerance gene and crop variety for commercial use, and no others have been submitted for approval.
Load more

Recommended publications
  • A Single Tree Model to Consistently Simulate Cooling, Shading, and Pollution Uptake of Urban Trees
    International Journal of Biometeorology https://doi.org/10.1007/s00484-020-02030-8 ORIGINAL PAPER A single tree model to consistently simulate cooling, shading, and pollution uptake of urban trees Rocco Pace1,2 & Francesco De Fino3 & Mohammad A. Rahman4 & Stephan Pauleit4 & David J. Nowak5 & Rüdiger Grote1 Received: 3 April 2020 /Revised: 24 September 2020 /Accepted: 6 October 2020 # The Author(s) 2020 Abstract Extremely high temperatures, which negatively affect the human health and plant performances, are becoming more frequent in cities. Urban green infrastructure, particularly trees, can mitigate this issue through cooling due to transpiration, and shading. Temperature regulation by trees depends on feedbacks among the climate, water supply, and plant physiology. However, in contrast to forest or general ecosystem models, most current urban tree models still lack basic processes, such as the consideration of soil water limitation, or have not been evaluated sufficiently. In this study, we present a new model that couples the soil water balance with energy calculations to assess the physiological responses and microclimate effects of a common urban street-tree species (Tilia cordata Mill.) on temperature regulation. We contrast two urban sites in Munich, Germany, with different degree of surface sealing at which microclimate and transpiration had been measured. Simulations indicate that differences in wind speed and soil water supply can be made responsible for the differences in transpiration. Nevertheless, the calculation of the overall energy balance showed that the shading effect, which depends on the leaf area index and canopy cover, contributes the most to the temperature reduction at midday. Finally, we demonstrate that the consideration of soil water availability for stomatal conductance has realistic impacts on the calculation of gaseous pollutant uptake (e.g., ozone).
    [Show full text]
  • The Impacts of Increasing Drought on Forest Dynamics, Structure, and Biodiversity in the United States
    Global Change Biology (2016) 22, 2329–2352, doi: 10.1111/gcb.13160 SPECIAL FEATURE The impacts of increasing drought on forest dynamics, structure, and biodiversity in the United States JAMES S. CLARK1 , LOUIS IVERSON2 , CHRISTOPHER W. WOODALL3 ,CRAIGD.ALLEN4 , DAVID M. BELL5 , DON C. BRAGG6 , ANTHONY W. D’AMATO7 ,FRANKW.DAVIS8 , MICHELLE H. HERSH9 , INES IBANEZ10, STEPHEN T. JACKSON11, STEPHEN MATTHEWS12, NEIL PEDERSON13, MATTHEW PETERS14,MARKW.SCHWARTZ15, KRISTEN M. WARING16 andNIKLAUS E. ZIMMERMANN17 1Nicholas School of the Environment, Duke University, Durham, NC 27708, USA, 2Forest Service, Northern Research Station 359 Main Road, Delaware, OH 43015, USA, 3Forest Service 1992 Folwell Avenue,Saint Paul, MN 55108, USA, 4U.S. Geological Survey, Fort Collins Science Center Jemez Mountains Field Station, Los Alamos, NM 87544, USA, 5Forest Service, Pacific Northwest Research Station, Corvallis, OR 97331, USA, 6Forest Service, Southern Research Station, Monticello, AR 71656, USA, 7Rubenstein School of Environment and Natural Resources, University of Vermont, 04E Aiken Center, 81 Carrigan Dr., Burlington, VT 05405, USA, 8Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106, USA, 9Department of Biology, Sarah Lawrence College, New York, NY 10708, USA, 10School of Natural Resources and Environment, University of Michigan, 2546 Dana Building, Ann Arbor, MI 48109, USA, 11U.S. Geological Survey, Southwest Climate Science Center and Department of Geosciences, University of Arizona, 1064 E. Lowell
    [Show full text]
  • Comparing Water-Related Plant Functional Traits Among Dominant Grasses of the Colorado Plateau: Implications for Drought Resistance
    Plant Soil https://doi.org/10.1007/s11104-019-04107-9 REGULAR ARTICLE Comparing water-related plant functional traits among dominant grasses of the Colorado Plateau: Implications for drought resistance David L. Hoover & Kelly Koriakin & Johanne Albrigtsen & Troy Ocheltree Received: 7 September 2018 /Accepted: 24 April 2019 # This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2019 Abstract above- and belowground biomass, and morphology, Background and aims Water is the primary limiting then assessed how these traits varied by species, and factor for plants in drylands, which are projected to photosynthetic pathway. become even drier with climate change. Plant functional Results Individual water-related traits varied widely, but traits related to water influences individual performance, did not consistently vary by photosynthetic pathway. community composition, and can provide insight into We identified three unique functional trait syndromes which species will be most vulnerable to drought. that could be classified as either conservative or non- Methods Here, we used a trait-based approach to exam- conservative with regard to water use. ine key water-related traits of five perennial grasses of Conclusions Variation in water-related traits may be the Colorado Plateau, with the goals of identifying func- key to the coexistence of species in drylands, but there tional trait syndromes, and assessing vulnerability to is uncertainty as which traits or functional trait syn- drought. We examined 14 traits including hydraulic, dromes will be most vulnerable to changes in climate. Based on the traits examined here, and forecast changes Responsible Editor: Ian Dodd.
    [Show full text]
  • Tree-Ring Variation in Pinyon Predicts Likelihood of Death Following Severe Drought
    November 2000 NOTES 3237 Ecology, 81(11), 2000, pp. 3237±3243 q 2000 by the Ecological Society of America TREE-RING VARIATION IN PINYON PREDICTS LIKELIHOOD OF DEATH FOLLOWING SEVERE DROUGHT KIONA OGLE,1 THOMAS G. WHITHAM, AND NEIL S. COBB Northern Arizona University, Department of Biological Sciences and the Merriam-Powell Center for Environmental Research, Flagstaff, Arizona 86011 USA Abstract. A severe drought in northern Arizona caused widespread pinyon (Pinus edulis) mortality, exceeding 40% in some populations. We measured tree-ring widths of pinyons that survived and that died in three sites designated as ``high,'' ``medium,'' and ``low'' stress. Growth characteristics during the previous 10±15 years can be used to predict the likelihood of drought-induced death; dead trees exhibited 1.5 times greater variation in growth than live trees. A model of ring-width deviations vs. drought severity showed a loss of ``climatic sensitivity'' with age in dead trees. These differences were independent of site. We found two distinct tree types that are predisposed to die during drought; highly sensitive young trees, and insensitive older trees. As the Southwest has a dynamic climate typi®ed by severe droughts, it is important to understand how droughts act as bottleneck events to affect a dominant tree in a major vegetation type of the United States. Key words: climatic sensitivity; drought; environmental stress; mortality, likelihood following drought; Pinus edulis; pinyon pine; tree rings. INTRODUCTION (Betancourt 1987, Betancourt et al. 1990), allowing us General circulation models project that a doubling to place current changes into a paleoecological per- spective. From a community perspective, much is of atmospheric CO2 in the near future will result in shifts in the spatio-temporal distribution of precipita- known about how environmental stress affects pinyons, tion (e.g., Cubasch et al.
    [Show full text]
  • Responses and Differences in Tolerance to Water Shortage Under
    Article Responses and Differences in Tolerance to Water Shortage under Climatic Dryness Conditions in Seedlings from Quercus spp. and Andalusian Q. ilex Populations Bonoso San-Eufrasio 1, Rosa Sánchez-Lucas 1,2, Cristina López-Hidalgo 1,3 , Victor M. Guerrero-Sánchez 1 , María Ángeles Castillejo 1 , Ana María Maldonado-Alconada 1, Jesús V. Jorrín-Novo 1 and María-Dolores Rey 1,* 1 Agroforestry and Plant Biochemistry, Proteomics and Systems Biology, Department of Biochemistry and Molecular Biology, University of Cordoba, UCO-CeiA3, 14014 Cordoba, Spain; [email protected] (B.S.-E.); [email protected] (R.S.-L.); [email protected] (C.L.-H.); [email protected] (V.M.G.-S.); [email protected] (M.Á.C.); [email protected] (A.M.M.-A.); [email protected] (J.V.J.-N.) 2 School of Biosciences, University of Birmingham, Edgbaston B15 2TT, UK 3 Plant Physiology, Department of Organisms and Systems Biology, University Institute of Biotechnology of Asturias (IUBA), University of Oviedo, 33006 Asturias, Spain * Correspondence: [email protected] Received: 27 May 2020; Accepted: 19 June 2020; Published: 24 June 2020 Abstract: Analyzing differences in tolerance to drought in Quercus spp., and the characterization of these responses at the species and individual population level, are imperative for the selection of resilient elite genotypes in reforestation programs. The main objective of this work was to evaluate differences in the response and tolerance to water shortage under in five Quercus spp. and five Andalusian Q. ilex populations at the inter- and intraspecies level. Six-month-old seedlings grown in perlite were subjected to drought treatments by withholding water for 28 days under mean 37 ◦C 2 temperature, 28 W m− solar irradiance, and 41% humidity.
    [Show full text]
  • Differential Drought Responses Between Saplings and Adult Trees in Four Co-Occurring Species of New England
    Trees (2005) 19: 442–450 DOI 10.1007/s00468-004-0403-2 ORIGINAL ARTICLE Jin-Sheng He · Qi-Bin Zhang · F. A. Bazzaz Differential drought responses between saplings and adult trees in four co-occurring species of New England Received: 25 March 2004 / Accepted: 18 November 2004 / Published online: 6 January 2005 C Springer-Verlag 2005 Abstract Tree-ring characteristics in four species were ex- mature trees of red maple and paper birch differed signifi- amined to address whether co-occurring mature trees of dif- cantly in drought responses, but this was not true in sugar ferent successional status respond differently to drought, maple and yellow birch. Our results do not support a gen- and whether saplings of these species have a greater re- erally greater response in saplings than in mature trees, sponse to drought than mature trees. We examined saplings nor an early- versus late successional difference in drought and mature trees of paper birch, yellow birch, red maple and responses. sugar maple, which varied in successional status (shade- tolerance) and co-occurred at Harvard Forest, Petersham, Keywords Drought . Dendrochronology . Ontogeny . Mass., USA. Three drought events in 1964–1966, 1981 and Temperate forest . Harvard Forest 1995 were identified using climate data. For mature trees, there was no significant interspecific difference in relative changes in ring-width index (RWI) during the 1964–1966 Introduction and 1995 drought events. However, the interspecific differ- ence was significant in the 1981 drought event. Response In ecology, experimental results from tree seedlings function analysis for mature trees showed that the radial and saplings are widely used to extrapolate to possible growth of sugar maple was mainly controlled by spring responses of mature individuals (Ehleringer and Field and summer precipitation, red maple by spring and sum- 1993).
    [Show full text]
  • Global Diversity of Drought Tolerance and Grassland Climate-Change Resilience
    LETTERS PUBLISHED ONLINE: 5 AUGUST 2012 | DOI: 10.1038/NCLIMATE1634 Global diversity of drought tolerance and grassland climate-change resilience Joseph M. Craine1*, Troy W. Ocheltree1, Jesse B. Nippert1, E. Gene Towne1, Adam M. Skibbe1, Steven W. Kembel2 and Joseph E. Fargione3 Drought reduces plant productivity, induces widespread plant However, present functional trait data are insufficient to predict mortality and limits the geographic distribution of plant how drought may alter the functional composition of grasslands. species1–7. As climates warm and precipitation patterns shift To better understand drought tolerance in grasslands, we in the future8,9, understanding the distribution of the diver- assessed physiological drought tolerance and a number of other sity of plant drought tolerance is central to predicting future leaf functional traits for 426 grass species. Plants can tolerate ecosystem function and resilience to climate change10–12. These environmental drought by accessing stable or stored water questions are especially pressing for the world’s 11,000 grass sources or even speeding reproduction to precede drought-induced species13, which dominate a large fraction of the terrestrial mortality. Because grasses store too little water or carbon to biosphere14, yet are poorly characterized with respect to re- maintain shoots during extended droughts, long-term resistance sponses to drought. Here, we show that physiological drought for grasses to low water potentials is probably first approximated tolerance, which varied tenfold among 426 grass species, is by their physiological tolerance of drought. Here, physiological well distributed both climatically and phylogenetically, sug- drought tolerance was assessed as the critical leaf water potential gesting most native grasslands are likely to contain a high (Ψcrit) at which stomatal conductance fell below an ecological diversity of drought tolerance.
    [Show full text]
  • Paleoclimate and Current Climate Collectively Shape the Phylogenetic And
    bioRxiv preprint doi: https://doi.org/10.1101/2020.06.02.128975; this version posted June 3, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 Paleoclimate and current climate collectively shape the phylogenetic and 2 functional diversity of trees worldwide 3 Wen-Yong Guo1,2 *, Josep M. Serra-Diaz3, Franziska Schrodt4, Wolf L. Eiserhardt2, Brian S. 4 Maitner5, Cory Merow6, Cyrille Violle7, Anne Blach-Overgaard1,2, Jian Zhang8, Madhur Anand9, 5 Michaël Belluau10, Hans Henrik Bruun11, Chaeho Byun12, Jane A. Catford13, Bruno E. L. 6 Cerabolini14, Eduardo Chacón-Madrigal15, Daniela Ciccarelli16, Johannes H. C. Cornelissen17, Anh 7 Tuan Dang-Le18, Angel de Frutos19, Arildo S. Dias20, Aelton B. Giroldo21, Alvaro G. Gutiérrez22, 8 Wesley Hattingh23, Tianhua He24,25, Peter Hietz26, Nate Hough-Snee27, Steven Jansen28, Jens 9 Kattge19,29, Tamir Klein30, Benjamin Komac31, Nathan Kraft32, Koen Kramer33, Sandra Lavorel34, 10 Christopher H. Lusk35, Adam R. Martin36, Maurizio Mencuccini37,38, Sean T. Michaletz39, Vanessa 11 Minden40,41, Akira S. Mori42, Ülo Niinemets43, Yusuke Onoda44, Renske E. Onstein19, Josep 12 Peñuelas38,45, Valério D. Pillar46, Jan Pisek47, Matthew J. Pound48, Bjorn J.M. Robroek49, Brandon 13 Schamp50, Martijn Slot51, Ênio Sosinski52, Nadejda A. Soudzilovskaia53, Nelson Thiffault54, Peter 14 van Bodegom53, Fons van der Plas55, Ian
    [Show full text]
  • Climate Change, Water and Food Security
    Cover picture: Irrawaddy Delta, Myanmar - September 2008 (© Swiatek Wojtkowiak) Copies of FAO publications can be requested from: SALES AND MARKETING GROUP Information Division Food and Agriculture Organization of the United Nations Viale delle Terme di Caracalla 00100 Rome, Italy E-mail: [email protected] Fax: (+39) 06 57053360 Web site: http://www.fao.org FAO WATER Climate change, water REPORTS and food security 36 by Hugh Turral FAO consultant Jacob Burke and Jean-Marc Faurès FAO Land and Water Division FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 2011 The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by FAO in preference to others of a similar nature that are not mentioned. ISBN 978-92-5- All rights reserved. FAO encourages reproduction and dissemination of material in this information product. Non-commercial uses will be authorized free of charge, upon request. Reproduction for resale or other commercial purposes, including educational purposes, may incur fees. Applications for permission to reproduce or disseminate FAO copyright materials, and all queries concerning rights and licences, should be addressed by e-mail to [email protected] or to the Chief, Publishing Policy and Support Branch, Office of Knowledge Exchange, Research and Extension, FAO, Viale delle Terme di Caracalla, 00153 Rome, Italy.
    [Show full text]
  • Tilia Cordata Mill.) and Black Locust (Robinia Pseudoacacia L.)
    Article The Urban Environment Can Modify Drought Stress of Small-Leaved Lime (Tilia cordata Mill.) and Black Locust (Robinia pseudoacacia L.) Astrid Moser 1,*, Thomas Rötzer 1, Stephan Pauleit 2 and Hans Pretzsch 1 1 Forest Growth and Yield Science, School of Life Sciences Weihenstephan, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, Freising 85354, Germany; [email protected] (T.R.); [email protected] (H.P.) 2 Strategic Landscape Planning and Management, School of Life Sciences Weihenstephan, Technische Universität München, Emil-Ramann-Str. 6, Freising 85354, Germany; [email protected] * Correspondence: [email protected]; Tel.: +49-8161-71-4719 Academic Editors: Francisco Escobedo, Stephen John Livesley and Justin Morgenroth Received: 8 January 2016; Accepted: 11 March 2016; Published: 17 March 2016 Abstract: The urban environment characterized by various stresses poses challenges to trees. In particular, water deficits and high temperatures can cause immense drought stress to urban trees, resulting in reduced growth and die-off. Drought-tolerant species are expected to be resilient to these conditions and are therefore advantageous over other, more susceptible species. However, the drought tolerance of urban trees in relation to the specific growth conditions in urban areas remains poorly researched. This study aimed to analyze the annual growth and drought tolerance of two common urban tree species, namely small-leaved lime (Tilia cordata Mill. (T. cordata)) and black locust (Robinia pseudoacacia L. (R. pseudoacacia)), in two cities in southern Germany in relation to their urban growing conditions. Marked growth reductions during drought periods and subsequent fast recovery were found for R.
    [Show full text]
  • Water-Use Strategies of Trees in a Secondary Successional Tropical Dry Forest
    Tree Physiology 36, 208–217 doi:10.1093/treephys/tpv124 Research paper Exploiting water versus tolerating drought: water-use strategies of trees in a secondary successional tropical dry forest Fernando Pineda-García1,5, Horacio Paz2, Frederick C. Meinzer3 and Guillermo Angeles4 Downloaded from 1Escuela Nacional de Estudios Superiores, Universidad Nacional Autónoma de México Unidad Morelia, Antigua Carretera a Patzcuaro 8701, CP 58190, Morelia, Mexico; 2Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México Campus Morelia, 58190 Morelia, Mexico; 3USDA Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR 97331, USA; 4Red de Ecología Funcional, Instituto de Ecología A.C., 91070 Xalapa, Mexico; 5Corresponding author ([email protected]) http://treephys.oxfordjournals.org/ Received July 15, 2015; accepted November 4, 2015; published online December 18, 2015; handling Editor Guillermo Goldstein In seasonal plant communities where water availability changes dramatically both between and within seasons, understanding the mechanisms that enable plants to exploit water pulses and to survive drought periods is crucial. By measuring rates of physiological processes, we examined the trade-off between water exploitation and drought tolerance among seedlings of trees of a tropical dry forest, and identified biophysical traits most closely associated with plant water-use strategies. We also explored whether early and late secondary successional species occupy different
    [Show full text]
  • Are Northeastern U.S. Forests Vulnerable to Extreme Drought? Adam P
    Coble et al. Ecological Processes (2017) 6:34 DOI 10.1186/s13717-017-0100-x REVIEW Open Access Are Northeastern U.S. forests vulnerable to extreme drought? Adam P. Coble1*, Matthew A. Vadeboncoeur2, Z. Carter Berry1, Katie A. Jennings2, Cameron D. McIntire1, John L. Campbell3, Lindsey E. Rustad3, Pamela H. Templer4 and Heidi Asbjornsen1,2 Abstract In the Northeastern U.S., drought is expected to increase in frequency over the next century, and therefore, the responses of trees to drought are important to understand. There is recent debate about whether land-use change or moisture availability is the primary driver of changes in forest species composition in this region. Some argue that fire suppression from the early twentieth century to present has resulted in an increase in shade-tolerant and pyrophobic tree species that are drought intolerant, while others suggest precipitation variability as a major driver of species composition. From this debate, an emerging hypothesis is that mesophication and increases in the abundance of mesophytic genera (e.g., Acer, Betula,andFagus) resulted in forests that are more vulnerable to drought. This review examines the published literature and factors that contribute to drought vulnerability of Northeastern U.S. forests. We assessed two key concepts related to drought vulnerability, including drought tolerance (ability to survive drought) and sensitivity (short-term responses to drought),withafocusonNortheasternU.S. species. We assessed drought-tolerance classifications for species, which revealed both consistencies and inconsistencies, as well as contradictions when compared to actual observations, such as higher mortality for drought-tolerant species. Related to drought sensitivity, recent work has focused on isohydric/ anisohydric regulation of leaf water potential.
    [Show full text]