Ryu Y.,University of California at Berkeley |
Ryu Y.,Harvard University |
Baldocchi D.D.,University of California at Berkeley |
Verfaillie J.,University of California at Berkeley |
And 6 more authors.
Agricultural and Forest Meteorology | Year: 2010
We developed and tested the use of light emitting diodes (LEDs) to monitor vegetation reflectance in narrow spectral bands as a tool suitable for quantifying and monitoring ecosystem structure, function and metabolism. LEDs are appealing because they are inexpensive, small and reliable light sources that, when used in reverse mode, can measure spectrally selective radiation. We selected LEDs in red and near-infrared wavebands as they are used to calculate the normalized difference vegetation index (NDVI). The lab experiments revealed that the LEDs showed linear relation with a hyper-spectral spectroradiometer (R2>0.94 and 0.99 for red and NIR, respectively) and marginal sensitivity to temperature. To test the efficacy of this novel sensor, we measured spectral reflectance with LEDs over an annual grassland in California over 3.5 years. The LED-sensor captured daily to interannual variation of the spectral reflectance at the two bands with reliable and stable performance. The spectral reflectance in the two bands and NDVI proved to be useful to identify the leaf-on and leaf-off dates (mean bias errors of 5.3 and 4.2 days, respectively) and to estimate canopy photosynthesis (R2=0.91). We suggest that this novel instrument can monitor other structural and functional (e.g. leaf area index, leaf nitrogen) variables by employing LEDs that have other specific wavelengths bands. Considering that off-the-shelf LEDs cover a wide range of wavebands from the ultraviolet to near-infrared regions, we believe that the research community could explore a range of similar instruments across a range of bands for a variety of ecological applications. © 2010 Elsevier B.V.
Esprito-Santo F.D.B.,University of New Hampshire |
Keller M.,University of New Hampshire |
Keller M.,International Institute of Tropical Forestry |
Keller M.,NEON Inc. |
And 5 more authors.
Geophysical Research Letters | Year: 2010
We analyzed the pattern of large forest disturbances or blow-downs apparently caused by severe storms in a mostly unmanaged portion of the Brazilian Amazon using 27 Landsat images and daily precipitation estimates from NOAA satellite data. For each Landsat a spectral mixture analysis (SMA) was applied. Based on SMA, we detected and mapped 279 patches (from 5 ha to 2,223 ha) characteristic of blow-downs. A total of 21,931 ha of forest were disturbed. We found a strong correlation between occurrence of blow-downs and frequency of heavy rainfall (Spearman's rank, r2 = 0.84, p < 0.0003). The recurrence intervals of large disturbances were estimated to be 90,000 yr for the eastern Amazon and 27,000 yr for the western Amazon. This suggests that weather patterns affect the frequency of large forest disturbances that may produce different rates of forest turnover in the eastern and western Amazon basin. Copyright © 2010 by the American Geophysical Union.
Weng E.,University of Oklahoma |
Luo Y.,University of Oklahoma |
Wang W.,NASA |
Wang H.,University of Oklahoma |
And 4 more authors.
Journal of Geophysical Research: Biogeosciences | Year: 2012
Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x] = U·τe· λ/λ+Sτ1, where U is ecosystem carbon influx, τe is ecosystem carbon residence time, and τ1 is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval (λ) and the mean disturbance severity (s). It is a Michaelis-Menten-type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model, for example, approximately 1.8 Pg C will be lost in the high-latitude regions of North America (>45°N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of the twenty-first century, which will require around 12% increases in net primary productivity (NPP) to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events. © 2012. American Geophysical Union.
News Article | December 16, 2015
Paris deal done Negotiations at the Paris climate-change talks sealed a deal between 195 nations to limit warming to “well below” 2 °C above pre-industrial temperatures. The 32-page package was made on 12 December after 2 weeks of talks, and commits most nations to significant reductions in carbon emissions. The agreement notes that vulnerable low-lying countries are set to face rising sea levels and stronger storms. See page 315 for more. Open-data accord Four international science lobby groups have launched a joint accord supporting open data as a tool for more-equitable science. The initiative, announced on 9 December in Pretoria during the first Science Forum South Africa, attempts to make it easier for developing countries to participate in research on a global level. It is also the first attempt to unify the fragmented activities of the four bodies, which represent different disciplines and global regions: the International Council for Science, the InterAcademy Partnership, the International Social Science Council and the World Academy of Sciences. Venus probe enters orbit Japan’s Akatsuki probe is circling Venus on an even-closer orbit than mission managers had hoped for, the Japan Aerospace Exploration Agency announced on 9 December. In 2010, Akatsuki missed its first chance to enter into orbit; it made a second, successful attempt this month. At its closest approach, the probe will fly just 400 kilometres above Venus’s surface, from which point researchers aim to study the planet’s atmosphere. Three of the craft’s five cameras have already been confirmed as functional after their extra five years in space. This image was taken by the ultraviolet imager from about 72,000 kilometres above Venus’s surface. EU data-mining The European Commission confirmed on 9 December that it wants to propose legislation to exempt certain types of text and data mining from copyright laws. As part of wider copyright reform, public-interest research organizations would be allowed to mine text and data from journal articles for research purposes without having to ask permission from the copyright owner. Researchers worried about legal restrictions on the data mining have long campaigned for the change. Gain of function The US National Science Advisory Board for Biosecurity will convene on 7 January in Bethesda, Maryland, to assess the risks and benefits of ‘gain-of-function’ research — work intended to increase the virulence, transmissibility or host range of pathogens. The meeting will consider the findings of a 1,006-page risk–benefit assessment by the Gryphon Scientific consultancy in Takoma Park, Maryland, published on 11 December. The United States introduced a moratorium in October last year on federal funding of such research on the agents that cause influenza, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). AIDS funding cut In a readjustment of priorities announced on 11 December, the US National Institutes of Health (NIH) will no longer put 10% of its science budget towards AIDS research, overturning a requirement of more than 20 years. The policy has been controversial, with opponents arguing that the number of HIV/AIDS deaths dropped precipitously during this time. The NIH director’s advisory council said that, as existing grants end, the move will eventually free up hundreds of millions of dollars for research on other diseases. The agency will refocus its remaining AIDS budget away from basic biology and towards the creation of specific therapies and vaccines. Animal names safe Thanks to gifts totalling S$1.35 million (US$959,000), the International Commission on Zoological Nomenclature (ICZN) secretariat will be able to continue its role of ensuring that animal species are named in a systematic fashion. The commission had been facing insolvency. Based at the National University of Singapore, the ICZN enforces a globally accepted nomenclature code to ensure that each species has a unique and scientifically appropriate name; around 15,000 new species are described annually. The philanthropic Lee Foundation in Singapore provided nearly all of the endowment, the ICZN announced on 14 December in Berlin at a joint meeting with the International Union of Biological Sciences. DOE science chief Cherry Murray, a physicist at Harvard University in Cambridge, Massachusetts, will be the new director of the US Department of Energy (DOE) science office. The US Senate confirmed her appointment on 10 December. The decision is considered surprising because most recent federal appointments have been blocked by the Senate — the previous nominee for the office, Michael Kastner, was not confirmed after his 2013 nomination. Murray, an expert in condensed-matter physics and photonics, will take office this month. Stellarator is go The world’s largest ‘stellarator’ fusion device roared into life on 10 December. The €1-billion (US$1.1-billion) Wendelstein 7-X, based at the Max Planck Institute for Plasma Physics in Greifswald, Germany, produced its first plasma (pictured), lasting for one-tenth of a second and reaching a temperature of around 1 million °C. Although the test run used helium, next year the device will start superheating hydrogen in experiments designed to explore the suitability of the technique for commercial fusion. The stellarator confines ionized gas using intricately interwoven magnetic coils. The design is difficult to construct but potentially a more stable alternative to the doughnut-shaped ‘tokamak’ used by the international ITER fusion project, based in southern France. NEON Inc. out The US National Science Foundation (NSF) has decided to replace the manager of the beleaguered US$434 million National Ecological Observatory Network, the company NEON, Inc. The decision comes after the company told the NSF in June that it was running $80 million over budget. That triggered a congressional hearing and warning from NSF that it might oust NEON, Inc. in favour of another operator. The construction of the remaining observatory sites will probably be overseen by another company. Chemicals combine Two of the world’s largest chemical and agricultural companies, Dow Chemical of Midland, Michigan, and DuPont of Wilmington, Delaware, will attempt to merge. On 11 December, the companies announced that subject to regulatory approval, they would combine forces to create a firm valued at US$130 billion. That would then break apart into three independent companies: one focused on agriculture, another on materials science and the third on speciality products. Dengue vaccine The first vaccine for preventing the tropical disease dengue fever has been approved for use in Mexico. The vaccine, Dengvaxia, developed by Sanofi Pasteur of Lyon, France, was approved on 9 December by Mexico for patients aged 9 to 45 who live in areas where dengue is endemic. The viral infection is carried by mosquitos, and the number of infections worldwide has risen rapidly in recent years. The vaccine protects against the four variants of the dengue virus, and was approved after a clinical-development programme that involved more than 40,000 people in 15 countries. Open intelligence A group of individuals and companies from Silicon Valley in California have formed a non-profit company to research artificial intelligence (AI) that is “likely to benefit humanity as a whole”. The company, OpenAI, has raised US$1 billion and is co-chaired by Elon Musk, chief executive of the electric-car company Tesla Motors and private space-flight firm SpaceX. Musk has previously urged caution when it comes to AI, warning that it could become “more dangerous than nukes”. The source of tantalum, a metal used in the electronics industry and for specialized mechanical parts, has shifted dramatically since 2000, according to a US Geological Survey report. In 2000, Australia was the world’s main source of tantalum (producing 45%), but in 2014 Rwanda produced most (50%). Tantalum is a ‘conflict mineral’, meaning that its sale may finance conflict in countries such as the Democratic Republic of the Congo, and buyers must check the metal’s source. See go.nature.com/wog3zu for more. The upper estimate on how many pieces of plastic smaller than 5 millimetres across had accumulated in the world’s oceans by 2014. The lower estimate is 15 trillion. Source: E. van Sebille et al. Environ. Res. Lett. 10, 124006 (2015). 18–21 December The European Society for Medical Oncology holds its Asia Congress in Singapore. go.nature.com/6vwgoh 19–22 December The International Liposome Society gathers its members at University College London to discuss the use of liposomes in drug and vaccine delivery. go.nature.com/jmj6uy
Gheysari M.,Isfahan University of Technology |
Loescher H.W.,NEON Inc. |
Loescher H.W.,University of Colorado at Boulder |
Sadeghi S.H.,Washington State University |
And 3 more authors.
Advances in Agronomy | Year: 2015
We examined the main and interactive effects of nitrogen (N) and deficit irrigation (DI) on the yield response factor (Ky), water use efficiency (WUE), and irrigation water use efficiency (IWUE) of silage maize from a semiarid region of Iran. Experiments were conducted in 2003 and 2004 that included three N fertigation rates (0, 150, and 200kgNha-1 N0, N150, and N200, respectively) and four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil water depletion, W1, W2, W3, and W4, respectively). The soil water content measurements showed that most of the water was extracted from the top 60cm of the soil profile. DI increased WUE for all N fertilizer treatments with the maximum value being observed at the W2 level. The average of the IWUE for the two years of the study showed that the lowest IWUE was 1.38kgm-3 for the N0W1 treatment, while the highest IWUE was 1.8kgm-3 for the N200W3 treatment. A linear relationship was observed between evapotranspiration and the total biomass for all N fertilizer levels in 2003 and 2004. The minimum Ky to water was obtained from the N0 level as 0.64 in 2003 whereas the maximum Ky was recorded from the N200 level as 0.95 in 2004. This reveals that higher N rates application would enhance corn yield sensitivity to water stress. Overall, the sensitivity of the silage maize to water stress was affected by different planting date and nitrogen fertilizer levels. We also discuss emergent trends in water and nutrient management in light of the increased need for food security in the face of changing climate and growing populations. © 2015 Elsevier Inc.
Arnone J.A.,Desert Research Institute |
Jasoni R.L.,Desert Research Institute |
Lucchesi A.J.,Desert Research Institute |
Larsen J.D.,Desert Research Institute |
And 5 more authors.
Journal of Ecology | Year: 2011
The occurrence and intensity of climate extremes, such as extremely warm years, are expected to continue to increase with increasing tropospheric radiative forcing caused by anthropogenic greenhouse gas emissions. Responses of terrestrial ecosystem processes and services - such as above-ground net primary productivity (ANPP) and maintenance of plant species diversity - to these extreme years for multiple years post-perturbation are poorly understood but can have significant feedback effects on net ecosystem CO2 uptake and ecosystem carbon sequestration. We exposed six 12000-kg intact natural tallgrass prairie monoliths to an extremely warm year (+4°C in 2003) in the second year of a 4-year study (2002-2005) using the EcoCELL whole-ecosystem controlled-environment, gas exchange facility. Six control monoliths were not warmed in the second year but were maintained under average field conditions. Natural diel and seasonal patterns in air temperature were maintained in both treatments throughout the study. Thus, with the exception of the second year in the 'warmed' treatment, we created 4years of nearly identical climate in all EcoCELLs. Interannual ANPP (10cm clipping height) responses of the entire plant community to the extreme year were largely determined by responses of the dominant C4 grasses. These included large decreases in ANPP in 2003 followed by complete recovery to levels observed in the control ecosystems in the year following warming. Species richness and productivity of the nitrogen-fixing plant functional group appeared to play a role in defining overall plant community ANPP, however, even though this richness and productivity could not explain the decrease in community ANPP observed in warmed ecosystems in the second year (2003) of the study or its recovery in the year after (2004). Surprisingly, very few of the 67 species present in plant communities during the 4-year study responded to the warm year at any time during or after the treatment. Synthesis. Results from this study indicate that as extreme climate years become more prevalent, their immediate and lagged impacts on collective ecosystem processes, such as whole-community ANPP, may be very pronounced, but effects on component ecosystem processes may be limited to the dominant plant functional group (ANPP). © 2011 The Authors. Journal of Ecology © 2011 British Ecological Society.
Voltz T.,FH Dresden |
Gooseff M.,Pennsylvania State University |
Ward A.S.,University of Iowa |
Singha K.,Colorado School of Mines |
And 2 more authors.
Journal of Geophysical Research: Earth Surface | Year: 2013
Patterns of riparian hydraulic gradients and stream-groundwater exchange in headwater catchments provide the hydrologic context for important ecological processes. Although the controls are relatively well understood, their dynamics during periods of hydrologic change is not. We investigate riparian hydraulic gradients over three different time scales in two steep, forested, headwater catchments in Oregon (WS01 and WS03) to determine the potential controls of reach-scale valley slope and cross-sectional valley geometry. Groundwater and stream stage data collected at high spatial and temporal resolutions over a period encompassing a 1.25 year storm and subsequent seasonal baseflow recession indicate that hydraulic gradients in both riparian aquifers exhibit strong persistence of down-valley dominance. Responses to rainfall do not support the simple conceptual models of increased riparian hydraulic gradient toward streams. Hydraulic gradient response in WS01 to both the seasonal baseflow recession and the storm suggested the potential for increased stream-groundwater exchange, but there was less evidence for this in WS03. Results from four constant-rate tracer injections in each stream showed a high baseline level of exchange overall, and both a slight seasonal increase (WS01) and slight decrease (WS03) in the riparian intrusion of tracer-labeled stream water as stream discharge receded. These results indicate that steep headwater valley floors host extensive stream water exchange and very little change in the water table gradients over 3 orders of magnitude of stream discharge. Key Points Riparian water tables did not develop strong stream-ward gradients during storm Riparian water tables varied little over 3 orders of magnitude stream discharge Stream-groundwater exchange varied little through baseflow recession ©2013. American Geophysical Union. All Rights Reserved.
Karpowicz B.M.,Southwest Research Institute |
Karpowicz B.M.,NEON INC. |
Steffes P.G.,Georgia Institute of Technology
Icarus | Year: 2013
In this work, a new equation of state for a H2-He-H2O-CH4 mixture is presented. The equation is optimized for the deep jovian atmosphere (∼100bars) where the NASA Juno Microwave Radiometer (MWR) will probe. The methodology used is based upon that of Lemmon and Jacobsen (Lemmon, E.W., Jacobsen, R.T. . J. Phys. Chem. Ref. Data 33, 593-+) and Kunz et al. (Kunz, O., Klimeck, R., Wagner, W., Jaeschke, M. . Technical Monograph, VDI-Verlag). This methodology is used in combination with available published thermodynamic measurements and with new pressure-Volume-Temperature (pVT) measurements of H2-H2O mixtures conducted with the jovian simulator described in Karpowicz and Steffes (Karpowicz, B.M., Steffes, P.G. . Icarus 212, 210-223). In addition to being necessary to interpret laboratory measurements, the new equation of state is important in developing temperature pressure profiles of the deep jovian atmosphere. This is demonstrated by incorporating the new equation of state into an updated version of the DeBoer (DeBoer, D.R. . Ph.D. Thesis, Georgia Institute of Technology) Thermo-Chemical Model (TCM), and viewing its effect on the resulting simulated jovian atmospheric profiles. © 2012 Elsevier Inc.
Brogan D.S.,Virginia Polytechnic Institute and State University |
Mcdonald W.M.,Virginia Polytechnic Institute and State University |
Lohani V.K.,Virginia Polytechnic Institute and State University |
Dymond R.L.,Virginia Polytechnic Institute and State University |
Bradner A.J.,NEON Inc
Advances in Engineering Education | Year: 2016
Education is essential for solving the complex water-related challenges facing society. The Learning Enhanced Watershed Assessment System (LEWAS) and the Online Watershed Learning System (OWLS) provide data creation and data sharing infrastructures, respectively, that combine to form an environmental learning tool. This system collects, integrates and stores real-time, high-frequency environmental monitoring data and imagery from a small urbanized watershed and makes it available to users at anytime from anywhere they have internet access. This paper discusses both the developmental and maintenance challenges associated with the LEWAS and the design details of the OWLS. A pilot test of the OWLS was implemented in a senior level hydrology course as a part of an NSF funded project. Results indicate that 80% of students (n = 30) valued the anywhere, anytime access to the data and 97% of students believed that access to the OWLS helped them to learn hydrologic concepts. A similar pilot test implemented in a community college freshman engineering course as part of the same project indicates that students (n=27) who used the OWLS felt that the OWLS assignment was valuable and relevant to their coursework even when their academic performance was underwhelming (40% correct on multiple choice questions). Future plans to expand the scope of the LEWAS-OWLS to cover environmental data from other geographical regions are discussed.
Johnson B.R.,NEON Inc. |
Kuester M.A.,NEON Inc. |
Kampe T.U.,NEON Inc. |
Keller M.,NEON Inc.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2010
The National Ecological Observatory Network (NEON) is a continental-scale research platform for discovering, understanding and forecasting the impacts of climate change, land-use change, and invasive species on ecology. Site-based flux tower and field measurements will be coordinated with high resolution, regional airborne remote sensing observations. This data combined with satellite observations, national data sets and ecosystem models will extend site-based and regional coverage to the continental scale. The NEON Airborne Observation Platform (AOP) will carry remote sensing instrumentation designed to achieve sub-meter to meter scale ground resolution to bridge scales from organism and stand scales to the scale of satellite based remote sensing. The capability of the airborne system will be well beyond existing systems in its ability to produce quantitative information about ecosystem structure and functioning covering nearly 2 million hectares each year for 30 years or more. © 2010 IEEE.