Kropp H.,Arizona State University |
Kropp H.,Colgate University |
Ogle K.,Northern Arizona University |
Vivoni E.R.,Arizona State University |
Hultine K.R.,Conservation and Collections
Ecosystems | Year: 2017
Evapotranspiration (ET) is an important water loss flux in ecosystem water cycles, and quantifying the spatial and temporal variation of ET can improve ecohydrological models in arid ecosystems. Plant neighbor interactions may be a source of spatial and temporal variation in ET due to their effects on the above- and belowground microclimate and increased water demand for transpiration. Over longer timescales (annual to multiple years), adjustments in plant physiological traits may occur in response to neighbor environments, potentially affecting the transpiration (T) component of ET. We used a dynamic soil water model to assess the sensitivity of ET and T estimates to neighbor effects on soil moisture via competition for water, aboveground microclimate effects via canopy shading, and physiological adjustments (specifically, root distribution, stomatal behavior, and canopy leaf area). We focus on a common desert shrub (Larrea tridentata) under different inter-specific neighbor environments and precipitation regimes. Neighbors impacted T of Larrea by as much as 75% at the patch scale (plant and surrounding soil) and 30% at the stand scale. Annual T estimates were highly sensitive to changes in soil moisture associated with competition for water, and the inclusion of physiological adjustments to neighbor environments significantly impacted seasonal T. Plant neighbor interactions can significantly influence ET and soil moisture, and their inclusion in models can help explain spatial and temporal variation in water fluxes in arid ecosystems. Furthermore, physiological adjustments to neighbor environments may be an important source of variation to include in models that operate over seasonal timescales or in studies focused on plant responses to precipitation under climate change. © 2017 Springer Science+Business Media New York
Madliger C.L.,University of Windsor |
Cooke S.J.,Carleton University |
Crespi E.J.,Washington State University |
Funk J.L.,Chapman University |
And 7 more authors.
Conservation Physiology | Year: 2016
The potential benefits of physiology for conservation are well established and include greater specificity of management techniques, determination of cause-effect relationships, increased sensitivity of health and disturbance monitoring and greater capacity for predicting future change. While descriptions of the specific avenues in which conservation and physiology can be integrated are readily available and important to the continuing expansion of the discipline of 'conservation physiology', to date there has been no assessment of how the field has specifically contributed to conservation success. However, the goal of conservation physiology is to foster conservation solutions and it is therefore important to assess whether physiological approaches contribute to downstream conservation outcomes and management decisions. Here, we present eight areas of conservation concern, ranging from chemical contamination to invasive species to ecotourism, where physiological approaches have led to beneficial changes in human behaviour, management or policy. We also discuss the shared characteristics of these successes, identifying emerging themes in the discipline. Specifically, we conclude that conservation physiology: (i) goes beyond documenting change to provide solutions; (ii) offers a diversity of physiological metrics beyond glucocorticoids (stress hormones); (iii) includes approaches that are transferable among species, locations and times; (iv) simultaneously allows for human use and benefits to wildlife; and (v) is characterized by successes that can be difficult to find in the primary literature. Overall, we submit that the field of conservation physiology has a strong foundation of achievements characterized by a diversity of conservation issues, taxa, physiological traits, ecosystem types and spatial scales. We hope that these concrete successes will encourage the continued evolution and use of physiological tools within conservation-based research and management plans. © The Author 2016.
Hultine K.R.,Conservation and Collections |
Grady K.C.,Northern Arizona University |
Wood T.E.,U.S. Geological Survey |
Shuster S.M.,Northern Arizona University |
And 2 more authors.
Nature Plants | Year: 2016
Climate change, particularly increased aridity, poses a significant threat to plants and the biotic communities they support. Dioecious species may be especially vulnerable to climate change given that they often exhibit spatial segregation of the sexes, reinforced by physiological and morphological specialization of each sex to different microhabitats. In dimorphic species, the overexpression of a trait by one gender versus the other may become suppressed in future climates. Data suggest that males will generally be less sensitive to increased aridity than co-occurring females and, consequently, extreme male-biased sex ratios are possible in a significant number of populations. The effects of male-biased sex ratios are likely to cascade to dependent community members, especially those that are specialized on one sex. © 2016 Macmillan Publishers Limited. All rights reserved.
News Article | September 29, 2016
For four days in September, scientists and engineers took over ExCel London. During this, the inaugural New Scientist Live festival, visitors were treated to everything from Comet 67P and supersonic cars, to probes and 3D printers. Ideas and discovery were the key themes of the festival, and this was reflected in the impressive line-up, that included astronaut Tim Peake, leading researchers, authors, speakers from all sectors of society. On Friday 23rd September, the Materials Today team hosted their own event at the festival. ‘Materials Today at NSLive’ brought together some of the best of materials science, to talk about topics as diverse as science communication and the use of modelling in materials development. It offered attendees a unique opportunity to network with, and learn from, thought leaders across the materials spectrum, exemplified by the welcome from Prof. Subra Suresh, Chair of the Elsevier Materials Science Council. He emphasized the value of communication between researchers and the public, and urged the diverse crowd to talk about their work more, setting the tone for the day. The busy London Docklands provided the perfect inspiration for discussions on the role of materials in society, which were kickstarted by the first speaker, Prof Mark Miodownik. As Director of the Institute of Making, Mark is a champion for linking materials research to the arts and humanities. And he made it clear that for him, interdisciplinary research will be the only way to meet the challenges of the 21st Century. He focused on three major problems – energy, cities and health – and talked about the role that materials science has to play in each. Something common to all is the reduction of waste. Speaking specifically about gadgets, he said “Close to half the periodic table is found in your smartphone. At end of life, they're blended together, with most never being reused. That's bonkers.” A more efficient use of materials was also at the heart of the second talk, from Prof. Abhay Pandit, Director of the Centre for Research in Medical Devices at the National University of Ireland, Galway. He started by putting current biomaterials into the context of the early days of mass manufacturing, “Nylon, silicones and stainless steel were not designed specifically for use in biology. We’re now looking for a better approach.” Part of his work is inspired by his own identity, and the fact that humans are living longer than ever before, “We are an ageing society. By 2050, 1 in 3 will be over 65. That comes with challenges." Ageing took on a different meaning for the next speaker, Dr. Eleanor Schofield, Head of Conservation and Collections Care at The Mary Rose Trust. She discussed the challenges of treating archaeological samples, and highlighted the importance of collaborations with academia to develop new, improved options. Preserving wood is particularly challenging, as Eleanor described, "We first sprayed the remains of the Mary Rose in polyethylene glycol. Once we'd done that, we could dry it, preserving the structure of the wood for many years to come." Iron nails embedded in the wood come with their own interesting chemistry, as does storing samples – both of which are active research projects that Eleanor is managing. The morning’s talks were followed by a fascinating and lively panel discussion on science communication. The chair, Dr Michael Weir from the University of Sheffield, was joined by Mark, Abhay, and Eleanor, alongside Dr Alan Leshner, CEO Emeritus of AAAS. They compared notes on what has worked well in the past, and what we’ll need to do in the future to inspire the next generation of materials scientists. All felt confident that there had been a shift in attitudes, and that scientists of all levels were now reaping the benefits of communicating with the public. After ably managing a series of tough questions from the audience, the panel closed the morning’s programme. The afternoon started with a computer-game-like bang, thanks to Prof. Emma Lundberg, from KTH Royal Institute of Technology. She spoke about the important role that gamers are playing in developing the Human Protein Atlas. Fans of the online game Eve Online have, for several months, been taking part in a citizen science project, to classify patterns in microscope images of proteins. Remarkably, since March, “The gamers have carried out 13 million classifications, and this has led to several new findings which will soon be published”. Prof. Nikola Marzari uses computers rather differently for his work. As Head of the Laboratory of Theory and Simulation of Materials at EPFL, multiscale modelling is his focus. He talked about the use of informatics in materials discovery, and emphasised the need for accuracy and realistic complexity in the models. One of Nicola’s current interests is nanostructures, “By looking at materials data and binding energies from a range of databases, we’ve identified more than 1800 potential 2D materials”. This was music to the ears of the day’s final speaker, Prof. Jonathan Coleman, Principal Investigator of the Low-Dimensional Nanostructures group at Trinity College Dublin. His research focuses on graphene and other 2D materials, but his talk was titled ‘kitchen physics’. He took the audience on a whistle-stop-tour of some of his group’s work, including graphene-rubber composites that can continuously measure blood pressure, and extracting graphene using a household blender (which, by the way, needs to be > 150W). This was followed by an afternoon panel chaired by Laurie Winkless, regular contributor to Materials Today. She was joined by Nikola, along with Prof. David Rugg from Rolls-Royce, and Prof. Sohini Kar-Narayan from the University of Cambridge. The topic up for discussion was discovery and development. The conversation started on the growing link between modelling and experiments in materials science, and approached the question “Will modelling ever replace lab work?” (The answer? No!) The panel also discussed the need for closer connections between academia and industry, and the changing nature of skills that tomorrow’s scientists will need. The audience again had lots of questions, which led to a stimulating discussion. The programme ended with a poster session, which hugely impressed the judges and the Elsevier Materials Science Council. All agreed that we should feel confident about the future of materials science in the UK. The networking continued into the evening, and it seems that several collaborations were forged over the ‘molecular cocktails’ and 3D printing on offer. Feedback for the event has been overwhelmingly positive, so expect to see another Materials Today event soon!
Judd W.S.,University of Florida |
Majure L.C.,Conservation and Collections |
Skean J.D.,Albion College |
Neubig K.M.,Southern Illinois University Carbondale
Rhodora | Year: 2015
In the course of a taxonomic revision of several clades of Greater Antillean Melastomataceae, we discovered a previously undescribed species, Miconia abscondita, from the Massif de la Hotte, Haiti. Miconia abscondita is based on a vegetative collection by Swedish botanist, E. L. Ekman, which was made in 1926. This new species is a member of the Mecranium clade, a group well supported on the basis of both morphological and molecular data, but which is highly embedded within the phylogenetic structure of the genus Miconia. Miconia abscondita is clearly placed within the Mecranium clade on the basis of DNA sequence data, and this placement also is supported by the form of its hairs and, especially, the pattern of stem indumentum; however, it matches no currently described species. Miconia abscondita is thus described, illustrated, and compared with putatively related and/or phenetically similar species. The discovery of M. abscondita brings to 25 the number of recognized species within the Mecranium clade and to 11 the number of species occurring in the Massif de la Hotte, Haiti, a region of exceptional biodiversity that is under continuous threat from anthropogenic pressure. © 2015 by the New England Botanical Club.
Hultine K.R.,Conservation and Collections |
Williams D.G.,University of Wyoming |
Dettman D.L.,University of Arizona |
Butterfield B.J.,Northern Arizona University |
Puente-Martinez R.,Conservation and Collections
Oecologia | Year: 2016
Volume-to-surface area ratio (V:S) across stem succulent taxa varies by almost two orders of magnitude. The broad range in V:S of cacti and other succulent species likely has considerable importance for adaptation since stem volume determines the storage capacity of water, carbon and nutrients and stem surface area is directly related to whole-stem photosynthetic capacity. We examined the intrinsic physiological tradeoffs across diverse stem morphologies in three divergent evolutionary groups where stem succulence is common: Cactoideae, Opuntioideae (Cactaceae) and Euphorbiaceae. We predicted that variation in physiological response to environmental conditions would be (1) constrained by stem V:S, and (2) detectable in the stable isotope ratios of plant tissues. Stable isotope ratios were measured in the spines/prickles of 62 stem-succulent species occurring in a common garden setting in Phoenix, AZ, USA. Biomass δ13C, δ2H and δ18O increased with V:S in Cactoideae only, possibly reflecting various levels of Crassulacean acid metabolism (CAM) strength in the other lineages. Within Cactoideae—group with the highest CAM strength and largest range in V:S—δ13C and δ18O increased 2.2 and 11.5 ‰, respectively, with a 22-fold increase in V:S. Both δ13C and V:S decreased with species climate-niche estimates of precipitation, indicating that stem morphology and physiology in Cactoideae may be constrained by available moisture. Taken together, these data suggest that physiological tradeoffs associated with stem V:S are detectable across broad evolutionary groups despite differences in CAM strength. © 2016 Springer-Verlag Berlin Heidelberg
Hultine K.R.,Conservation and Collections |
Bean D.W.,Palisade Insectary |
Dudley T.L.,University of California at Santa Barbara |
Gehring C.A.,Northern Arizona University
Integrative and Comparative Biology | Year: 2015
Desert riparian ecosystems of North America are hotspots of biodiversity that support many sensitive species, and are in a region experiencing some of the highest rates of climatic alteration in North America. Fremont cottonwood, Populus fremontii, is a foundation tree species of this critical habitat, but it is threatened by global warming and regional drying, and by a non-native tree/shrub, Tamarix spp., all of which can disrupt the mutualism between P. fremontii and its beneficial mycorrhizal fungal communities. Specialist herbivorous leaf beetles (Diorhabda spp.) introduced for biocontrol of Tamarix are altering the relationship between this shrub and its environment. Repeated episodic feeding on Tamarix foliage by Diorhabda results in varying rates of dieback and mortality, depending on genetic variation in allocation of resources, growing conditions, and phenological synchrony between herbivore and host plant. In this article, we review the complex interaction between climatic change and species introductions and their combined impacts on P. fremontii and their associated communities. We anticipate that (1) certain genotypes of P. fremontii will respond more favorably to the presence of Tamarix and to climatic change due to varying selection pressures to cope with competition and stress; (2) the ongoing evolution of Diorhabda's life cycle timing will continue to facilitate its expansion in North America, and will over time enhance herbivore impact to Tamarix; (3) defoliation by Diorhabda will reduce the negative impact of Tamarix on P. fremontii associations with mycorrhizal fungi; and (4) spatial variability in climate and climatic change will modify the capacity for Tamarix to survive episodic defoliation by Diorhabda, thereby altering the relationship between Tamarix and P. fremontii, and its associated mycorrhizal fungal communities. Given the complex biotic/abiotic interactions outlined in this review, conservation biologists and riparian ecosystem managers should strive to identify and conserve the phenotypic traits that underpin tolerance and resistance to stressors such as climate change and species invasion. Such efforts will greatly enhance conservation restoration efficacy for protecting P. fremontii forests and their associated communities. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.
Hultine K.R.,Conservation and Collections |
Burtch K.G.,University of Utah |
Ehleringer J.R.,University of Utah
Global Change Biology | Year: 2013
Air temperatures in the arid western United States are predicted to increase over the next century. These increases will likely impact the distribution of plant species, particularly dioecious species that show a spatial segregation of the sexes across broad resource gradients. On the basis of spatial segregation patterns, we hypothesized that temperature increases will have a greater negative impact on female plants compared with co-occurring male plants of dioecious species. This hypothesis was tested by examining the whole-plant carbon and water relations of 10-year-old female (n = 18) and male (n = 13) Acer negundo Sarg. trees grown in a common garden in Salt Lake City, UT. The trees were established from cuttings collected where the growing season temperature averaged about 6.5 °C cooler than at the common garden. During May and June, stem sap flux (Js) was similar between genders, but averaged 25% higher in males during the warmer months of July and August. Daytime canopy stomatal conductance (gs) per unit leaf area was 12% higher in females in May : June, but was 11% higher in males in July : August. We combined measurements of sap flux-scaled transpiration with measurements of tree allometry and δ13C of leaf soluble sugars to estimate whole-tree carbon assimilation (Atree) and water use efficiency (WUE) (Atree : Etree). Atree was similar between genders until late August when Atree was 32% higher in male trees. Atree : Etree was on average 7% higher in females than in males during the growing season. Patterns of Js, gs, Atree and Atree : Etree in the present study were in contrast to those previously reported for A. negundo genders under native growing season temperatures. Results suggest that the spatial segregation of the sexes could shift under global warming such that female plants lose their dominance in high-resource habitats, and males increase their dominance in relatively lower-resource habitats. © 2013 John Wiley & Sons Ltd.
Nagler P.L.,U.S. Geological Survey |
Pearlstein S.,University of Arizona |
Glenn E.P.,University of Arizona |
Brown T.B.,Australian National University |
And 3 more authors.
Remote Sensing of Environment | Year: 2014
We measured the rate of dispersal of saltcedar leaf beetles (Diorhabda carinulata), a defoliating insect released on western rivers to control saltcedar shrubs (Tamarix spp.), on a 63km reach of the Virgin River, U.S. Dispersal was measured by satellite imagery, ground surveys and phenocams. Pixels from the Moderate Resolution Imaging Spectrometer (MODIS) sensors on the Terra satellite showed a sharp drop in NDVI in midsummer followed by recovery, correlated with defoliation events as revealed in networked digital camera images and ground surveys. Ground surveys and MODIS imagery showed that beetle damage progressed downstream at a rate of about 25kmyr-1 in 2010 and 2011, producing a 50% reduction in saltcedar leaf area index and evapotranspiration by 2012, as estimated by algorithms based on MODIS Enhanced Vegetation Index values and local meteorological data for Mesquite, Nevada. This reduction is the equivalent of 10.4% of mean annual river flows on this river reach. Our results confirm other observations that saltcedar beetles are dispersing much faster than originally predicted in pre-release biological assessments, presenting new challenges and opportunities for land, water and wildlife managers on western rivers. Despite relatively coarse resolution (250m) and gridding artifacts, single MODIS pixels can be useful in tracking the effects of defoliating insects in riparian corridors. © 2013.
Williams D.G.,University of Wyoming |
Hultine K.R.,Conservation and Collections |
Dettman D.L.,University of Arizona
Journal of Experimental Botany | Year: 2014
Columnar cacti occur naturally in many habitats and environments in the Americas but are conspicuously dominant in very dry desert regions. These majestic plants are widely regarded for their cultural, economic, and ecological value and, in many ecosystems, support highly diverse communities of pollinators, seed dispersers, and frugivores. Massive amounts of water and other resources stored in the succulent photosynthetic stems of these species confer a remarkable ability to grow and reproduce during intensely hot and dry periods. Yet many columnar cacti are potentially under severe threat from environmental global changes, including climate change and loss of habitat. Stems in columnar cacti and other cylindrical-stemmed cacti are morphologically diverse; stem volume-to-surface area ratio (V:S) across these taxa varies by almost two orders of magnitude. Intrinsic functional trade-offs are examined here across a broad range of V:S in species of columnar cacti. It is proposed that variation in photosynthetic gas exchange, growth, and response to stress is highly constrained by stem V:S, establishing a mechanistic framework for understanding the sensitivity of columnar cacti to climate change and drought. Specifically, species that develop stems with low V:S, and thus have little storage capacity, are expected to express high mass specific photosynthesis and growth rates under favourable conditions compared with species with high V:S. But the trade-off of having little storage capacity is that low V:S species are likely to be less tolerant of intense or long-duration drought compared with high V:S species. The application of stable isotope measurements of cactus spines as recorders of growth, water relations, and metabolic responses to the environment across species of columnar cacti that vary in V:S is also reviewed. Taken together, our approach provides a coherent theory and required set of observations needed for predicting the responses of columnar cacti to climate change. © 2014 The Author.