National Ecological Observatory Network NEON

Boulder City, CO, United States

National Ecological Observatory Network NEON

Boulder City, CO, United States
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Kulacki K.J.,University of Notre Dame | Chaloner D.T.,University of Notre Dame | Larson J.H.,U.S. Geological Survey | Costello D.M.,University of Michigan | And 6 more authors.
Current Organic Chemistry | Year: 2011

Aquatic environments are being contaminated with a myriad of anthropogenic chemicals, a problem likely to continue due to both unintentional and intentional releases. To protect valuable natural resources, novel chemicals should be shown to be environmentally safe prior to use and potential release into the environment. Such proactive assessment is currently being applied to room-temperature ionic liquids (ILs). Because most ILs are water-soluble, their effects are likely to manifest in aquatic ecosystems. Information on the impacts of ILs on numerous aquatic organisms, focused primarily on acute LC50 and EC50 endpoints, is now available, and trends in toxicity are emerging. Cation structure tends to influence IL toxicity more so than anion structure, and within a cation class, the length of alkyl chain substituents is positively correlated with toxicity. While the effects of ILs on several aquatic organisms have been studied, the challenge for aquatic toxicology is now to predict the effects of ILs in complex natural environments that often include diverse mixtures of organisms, abiotic conditions, and additional stressors. To make robust predictions about ILs will require coupling of ecologically realistic laboratory and field experiments with standard toxicity bioassays and models. Such assessments would likely discourage the development of especially toxic ILs while shifting focus to those that are more environmentally benign. Understanding the broader ecological effects of emerging chemicals, incorporating that information into predictive models, and conveying the conclusions to those who develop, regulate, and use those chemicals, should help avoid future environmental degradation. © 2011 Bentham Science Publishers Ltd.


Kampe T.,National Ecological Observatory Network NEON | Berukoff S.,Data Products
Eos | Year: 2012

Understanding the functional response of ecosystems across multiple spatial and temporal scales is one of the fundamental challenges in ecology. More than 50 researchers attended a June workshop focused on scaling ecological data from local and regional scales to the continental scale hosted by the National Ecological Observatory Network (NEON). The workshop addressed key issues associated with the influence of scale on the interpretation of ecological variation, particularly in the context of continental-scale terrestrial ecology. These questions are particularly relevant to NEON, the first ecological observation platform designed to assess the natural and human causes and the biological consequences of environmental change at large scales. © 2012. American Geophysical Union. All Rights Reserved.


Van Leeuwen M.,Rochester Institute of Technology | Van Aardt J.A.N.,Rochester Institute of Technology | Kampe T.,National Ecological Observatory Network NEON | Krause K.,National Ecological Observatory Network NEON
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2015

Monitoring forest productivity and health is key to sustainable ecosystem management and informed decision making. A key parameter used in monitoring forest resources is the leaf area index (LAI), which is defined as the one-sided leaf area per unit ground area and is used to describe the canopy radiation regime, among other forest biophysical dynamics. Traditional optics-based methods to estimate LAI rely on the measurement of canopy transmission and foliage clumping. Extending optical methods to LiDAR data has been challenging and studies have reported effective LAI assessments, with no further quantification of foliage clumping. This study investigates the use of the box-counting method to assess the fractal dimension of point cloud data for contrasting forest types and along a gradient of foliage dispersal. We demonstrate the box-counting method on simulated 'range-to-hit', as well as acquired airborne discrete LiDAR data. Coherent results obtained from the different test cases hint at the potential of the box-counting fractal dimension to characterize foliage clumping and bode well for the use of clumping assessments in support of airborne, wall-to-wall estimates of LAI.


Loescher H.,National Ecological Observatory Network NEON | Loescher H.,University of Colorado at Boulder | Ayres E.,National Ecological Observatory Network NEON | Ayres E.,University of Colorado at Boulder | And 5 more authors.
PLoS ONE | Year: 2014

Soils are highly variable at many spatial scales, which makes designing studies to accurately estimate the mean value of soil properties across space challenging. The spatial correlation structure is critical to develop robust sampling strategies (e.g., sample size and sample spacing). Current guidelines for designing studies recommend conducting preliminary investigation(s) to characterize this structure, but are rarely followed and sampling designs are often defined by logistics rather than quantitative considerations. The spatial variability of soils was assessed across ∼1 ha at 60 sites. Sites were chosen to represent key US ecosystems as part of a scaling strategy deployed by the National Ecological Observatory Network. We measured soil temperature (Ts) and water content (SWC) because these properties mediate biological/ biogeochemical processes below- and above-ground, and quantified spatial variability using semivariograms to estimate spatial correlation. We developed quantitative guidelines to inform sample size and sample spacing for future soil studies, e.g., 20 samples were sufficient to measure Ts to within 10% of the mean with 90% confidence at every temperate and subtropical site during the growing season, whereas an order of magnitude more samples were needed to meet this accuracy at some high-latitude sites. SWC was significantly more variable than Ts at most sites, resulting in at least 10x more SWC samples needed to meet the same accuracy requirement. Previous studies investigated the relationship between the mean and variability (i.e., sill) of SWC across space at individual sites across time and have often (but not always) observed the variance or standard deviation peaking at intermediate values of SWC and decreasing at low and high SWC. Finally, we quantified how far apart samples must be spaced to be statistically independent. Semivariance structures from 10 of the 12- dominant soil orders across the US were estimated, advancing our continental-scale understanding of soil behavior. © 2014 Loescher et al.


Jones K.D.,Oregon State University | Jones K.D.,National Ecological Observatory Network NEON | Kaye T.N.,Oregon State University | Kaye T.N.,Institute for Applied Ecology
PLoS ONE | Year: 2014

Grassland prairies of western Oregon and Washington are among the most endangered ecosystems in the United States. Active management and restoration are needed to promote biodiversity in the region. To support plant production for use in habitat restoration, we developed germination protocols for greenhouse propagation of Iris tenax (Oregon iris). Dormancy was most effectively overcome (63% germination) by four weeks of warm stratification at 20/30uC followed by 6- 12 weeks of cold stratification at 5°C suggesting that I. tenax may have morphophysiological dormancy. This result was consistent across multiple source populations. © 2014 Jones, Kaye.


Roberti J.A.,National Ecological Observatory Network NEON | SanClements M.D.,National Ecological Observatory Network NEON | SanClements M.D.,University of Colorado at Boulder | Loescher H.W.,National Ecological Observatory Network NEON | And 3 more authors.
PLoS ONE | Year: 2014

Even though fine-root turnover is a highly studied topic, it is often poorly understood as a result of uncertainties inherent in its sampling, e.g., quantifying spatial and temporal variability. While many methods exist to quantify fine-root turnover, use of minirhizotrons has increased over the last two decades, making sensor errors another source of uncertainty. Currently, no standardized methodology exists to test and compare minirhizotron camera capability, imagery, and performance. This paper presents a reproducible, laboratory-based method by which minirhizotron cameras can be tested and validated in a traceable manner. The performance of camera characteristics was identified and test criteria were developed: we quantified the precision of camera location for successive images, estimated the trueness and precision of each camera's ability to quantify root diameter and root color, and also assessed the influence of heat dissipation introduced by the minirhizotron cameras and electrical components. We report detailed and defensible metrology analyses that examine the performance of two commercially available minirhizotron cameras. These cameras performed differently with regard to the various test criteria and uncertainty analyses. We recommend a defensible metrology approach to quantify the performance of minirhizotron camera characteristics and determine sensor-related measurement uncertainties prior to field use. This approach is also extensible to other digital imagery technologies. In turn, these approaches facilitate a greater understanding of measurement uncertainties (signal-to-noise ratio) inherent in the camera performance and allow such uncertainties to be quantified and mitigated so that estimates of fine-root turnover can be more confidently quantified. ©2014 Roberti et al.


Bracho R.,University of Florida | Starr G.,University of Alabama | Gholz H.L.,National Science Foundation | Martin T.A.,University of Florida | And 3 more authors.
Ecological Monographs | Year: 2012

Planted pine forests (plantations) in the southeastern United States are an important component of the continent's carbon balance. Forest carbon dynamics are affected by a range of factors including climatic variability. Multiyear droughts have affected the region in the past, and an increase in the frequency of drought events has been predicted. How this increased climatic variability will affect the capacity of the region's pine plantations to sequester carbon is not known. We used eddy covariance and biometric approaches to measure carbon dynamics over nine years in two slash pine plantations (Pinus elliottii var elliottii Englm) in north Florida, consisting of a newly planted and a mid-rotation stand. During this time, the region experienced two multiyear droughts (1999-2002 and 2006-2008), separated by a three-year wet period. Net ecosystem carbon accumulation measured using both approaches showed the same trends and magnitudes during plantation development. The newly planted site released 15.6 Mg C/ha during the first three years after planting, before becoming a carbon sink in year 4. Increases in carbon uptake during the early stages of stand development were driven by the aggrading leaf area index (LAI). After canopy closure, both sites were continuous carbon sinks with net carbon uptake (NEE) fluctuating between 4 and ∼8Mg C·ha -1· -1, depending on environmental conditions. Drought reduced NEE by ∼25% through its negative effects on both LAI and radiation-use efficiency, which resulted in a larger impact on gross ecosystem carbon exchange than on ecosystem respiration. While results indicate that responses to drought involved complex interactions among water availability, LAI, and radiation-use efficiency, these ecosystems remain carbon sinks under current management strategies and climatic variability. Variation within locations is primarily due to major disturbances, such as logging in the current study and, to a much lesser extent, local environmental fluctuations. When data from this study are compared to flux data from a broad range of forests worldwide, these ecosystems fill a data gap in the warm-temperate zone and support a broad maximum NEE (for closed-canopy forests) between 8°C and 20°C mean annual temperature. © 2012 by the Ecological Society of America.


Arredondo T.,San Luis Potosí Institute of Scientific Research and Technology | Garcia-Moya E.,Colegio de Mexico | Huber-Sannwald E.,San Luis Potosí Institute of Scientific Research and Technology | Loescher H.W.,National Ecological Observatory Network NEON | And 3 more authors.
Agricultural and Forest Meteorology | Year: 2016

Future precipitation changes in the semiarid grassland region in Central Mexico are expected to be larger for winter rainfall (-20%) than for summer rain (-10%). Winter rainfall however comprises a small proportion of annual precipitation (5-6%), therefore the potential effects on productivity are expected to be negligible. We are realizing however, that winter rain events are important controls of tiller population and consequently of grassland productivity. To attest its influence we examined rain legacy effects using rainout shelters, by reducing rainfall by 42% (2011) and 20% (2012) relative to unmanipulated rainfall on monodominant Bouteloua gracilis and mixed-species disturbed grasslands. In 2013 rainout shelters were removed to allow all incoming rain into the plots. Plant cover type was a significant predictor of aboveground productivity with monodominant B. gracilis consistently producing 50-80 g/m2 more than mixed stands. Decreased rainfall did not have negative effects on aboveground productivity except in an extreme drought year for the mixed-species grassland. We also observed a significant legacy effect of winter precipitation on summer aboveground productivity in both grassland types, but not to previous-year total precipitation. In spite of the large annual variability of soil ψ, leaf ψ fluctuated between -0.5 and -1.5 MPa most of the year suggesting a geologic source of water. © 2016 Elsevier B.V.


Jones K.D.,Oregon State University | Jones K.D.,Institute for Applied Ecology | Jones K.D.,National Ecological Observatory Network NEON | Kaye T.N.,Oregon State University | Kaye T.N.,Institute for Applied Ecology
Natural Areas Journal | Year: 2015

Sidalcea malviflora ssp. virgata (rose checkermallow) is a native forb in the Pacific Northwest, USA; it is a common species in upland prairies of the Willamette Valley, Oregon, and is a state listed endangered species in Washington State. This species provides a high value nectar supply for butterflies in this region, including the endangered Icaricia icarioides fenderi (Fender's blue butterfly), and is therefore targeted for inclusion in habitat restoration projects throughout the region. In past propagation efforts, S. malviflora ssp. virgata has demonstrated poor germination, indicating that there may be some dormancy in seeds of this species. We characterized dormancy and developed germination protocols to support greenhouse propagation of plants for habitat restoration projects. Sidalcea malviflora ssp. virgata has physical dormancy and may have some physiological dormancy as well. Highest germination (55%) was achieved by scarification followed by four weeks or more of cold moist stratification at 5 °C.


PubMed | National Ecological Observatory Network NEON and University of Colorado at Boulder
Type: Journal Article | Journal: PloS one | Year: 2014

Even though fine-root turnover is a highly studied topic, it is often poorly understood as a result of uncertainties inherent in its sampling, e.g., quantifying spatial and temporal variability. While many methods exist to quantify fine-root turnover, use of minirhizotrons has increased over the last two decades, making sensor errors another source of uncertainty. Currently, no standardized methodology exists to test and compare minirhizotron camera capability, imagery, and performance. This paper presents a reproducible, laboratory-based method by which minirhizotron cameras can be tested and validated in a traceable manner. The performance of camera characteristics was identified and test criteria were developed: we quantified the precision of camera location for successive images, estimated the trueness and precision of each cameras ability to quantify root diameter and root color, and also assessed the influence of heat dissipation introduced by the minirhizotron cameras and electrical components. We report detailed and defensible metrology analyses that examine the performance of two commercially available minirhizotron cameras. These cameras performed differently with regard to the various test criteria and uncertainty analyses. We recommend a defensible metrology approach to quantify the performance of minirhizotron camera characteristics and determine sensor-related measurement uncertainties prior to field use. This approach is also extensible to other digital imagery technologies. In turn, these approaches facilitate a greater understanding of measurement uncertainties (signal-to-noise ratio) inherent in the camera performance and allow such uncertainties to be quantified and mitigated so that estimates of fine-root turnover can be more confidently quantified.

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