Trace elements in sediments, water, and American coots (Fulica americana) at a coal-fired power plant in Texas, 1979-1982
No abstract available.
Bulletin of Environmental Contamination and Toxico↗
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Characterization of a linear DNA plasmid from the filamentous fungal plant pathogen Glomerella musae [Anamorph: Colletotrichum musae (Berk. and Curt.) arx.]
A 7.4-kilobase (kb) DNA plasmid was isolated from Glomerella musae isolate 927 and designated pGML1. Exonuclease treatments indicated that pGML1 was a linear plasmid with blocked 5' termini. Cell-fractionation experiments combined with sequence-specific PCR amplification revealed that pGML1 resided in mitochondria. The pGML1 plasmid hybridized to cesium chloride-fractionated nuclear DNA but not to A + T-rich mitochondrial DNA. An internal 7.0-kb section of pGML1 was cloned and did not hybridize with either nuclear or mitochondrial DNA from G. musae. Sequence analysis revealed identical terminal inverted repeats (TIR) of 520 bp at the ends of the cloned 7.0-kb section of pGML1. The occurrence of pGML1 did not correspond with the pathogenicity of G. musae on banana fruit. Four additional isolates of G. musae possessed extrachromosomal DNA fragments similar in size and sequence to pGML1.
Current Genetics↗
Using carbon isotope ratios to verify predictions of a model simulating the interaction between coastal plant communities and their effect on ground water salinity
As sea level rises in low-lying coastal islands, salt-tolerant (halophytic) coastal vegetation communities may be able to migrate inland, replacing the freshwater vegetation that is unable to tolerate salt stress. The pace of such shifts may be accelerated by a self-reinforcing feedback between the halophytic vegetation and salinity, as well as by frequent and intensified salinity pulses associated with the increasing impact of storm surges as a consequence of sea-level rise. We used a modification of a previously published spatially explicit individual-based model that simulates impacts on upland freshwater hammock communities from sea-level rise and storm surge to predict the interaction between three coastal communities: mangroves, hammocks, and pinelands. The model simulation predicted two qualitative characteristics regarding the interaction between these three different coastal communities: (1) mangroves and hammock communities tend to have ground water with high salinities, while at the same time pineland ground water salinity is low, and (2) pineland located at lower elevation relative to adjacent hammock will be negatively influenced by higher ground water salinities in hammocks, as it flows toward the lower elevation pineland. We tested these predictions using foliar δ13C of Conocarpus erectus collected from Big Pine Key as a proxy for ground water salinity. Measurements of ground water salinity via this proxy confirmed the two predictions of the model. Our approach provides an approximation of the impacts of sea-level rise on terrestrial vegetation communities, including threatened pineland communities, and can be used as a tool for management decisions.
Ecosystems↗
Detection of tannins in modern and fossil barks and in plant residues by high-resolution solid-state 13C nuclear magnetic resonance
Bark samples isolated from brown coal deposits in Victoria, Australia, and buried wood from Rhizophora mangle have been studies by high-resolution solid-state nuclear magnetic resonance (NMR) techniques. Dipolar dephasing 13 C NMR appears to be a useful method of detecting the presence of tannins in geochemical samples including barks, buried woods, peats and leaf litter. It is shown that tannins are selectively preserved in bark during coalification to the brown coal stage.
Organic Geochemistry↗
In search of the Holy Grail: Explanations for the coexistence of plant species
No abstracts available.
Trends in Ecology and Evolution↗
Plants and ventifacts delineate late Holocene wind vectors in the Coachella Valley, USA
Strong westerly winds that emanate from San Gorgonio Pass, the lowest point between Palm Springs and Los Angeles, California, dominate aeolian transport in the Coachella Valley of the western Sonoran Desert. These winds deposit sand in coppice dunes that are critical habitat for several species, including the state and federally listed threatened species Uma inornata , a lizard. Although wind directions are generally defined in this valley, the wind field has complex interactions with local topography and becomes more variable with distance from the pass. Local, dominant wind directions are preserved by growth patterns of Larrea tridentata (creosote bush), a shrub characteristic of the hot North American deserts, and ventifacts. Exceptionally long-lived, Larrea has the potential to preserve wind direction over centuries to millennia, shaped by the abrasive pruning of windward branches and the persistent training of leeward branches. Wind direction preserved in Larrea individuals and clones was mapped at 192 locations. Compared with wind data from three weather stations, Larrea vectors effectively reflect annual prevailing winds. Ventifacts measured at 24 locations record winds 10° more westerly than Larrea and appear to reflect the direction of the most erosive winds. Based on detailed mapping of local wind directions as preserved in Larrea , only the northern half of the Mission-Morongo Creek floodplain is likely to supply sand to protected U. inornata habitat in the Willow Hole ecological reserve.
California↗
Time to branch out? Application of hierarchical survival models in plant phenology
The sensitivity of phenology to environmental drivers can vary across geography and species. As such, models developed to predict phenology are typically site- or taxon-specific. Generation of site- and taxon-specific models is limited by the intensive in-situ phenological monitoring effort required to generate sufficient data to parameterize each model. Where in-situ phenological observations exist, the data are often subject to analytical issues due to the limited duration of any individual monitoring program, spotty site- and species- level coverage, lack of standardized methodology, and infrequent or variable census intervals. Together, these characteristics constrain our ability to make phenological inferences outside of select sites and taxa where long-duration, intensive monitoring has occurred. In this study, we leveraged two national, standardized phenology datasets to develop a multi-species and multi-site state-space survival model of the onset of deciduous tree and shrub spring (leaf out) and fall (leaf-color) events across temperate ecoregions of the United States. We used data from two national-scale phenological databases, a 9-year, broadly distributed dataset from the USA National Phenology Network and a 4-year dataset from the National Ecological Observatory Network, to quantify regional and interspecific variation in sensitivity to environmental drivers for both spring and fall leaf phenophases. Spring leaf out was generally promoted by longer days, spring growing degree day accumulation, overwinter chilling, and was suppressed by frost events, whereas fall leaf color was promoted by shorter days and cold accumulation. The sensitivity to most environmental drivers tended to be more variable among species than among the regions as defined here (EPA ecoregions of North America, excluding desert and tropical areas). The results of this study lay the groundwork for incorporating the growing collection of phenological observations into a generalized framework for predicting the transition states for any species, in any location.
Agricultural and Forest Meteorology↗
Seed flotation and germination of salt marsh plants: The effects of stratification, salinity, and/or inundation regime
We examined the effects of cold stratification and salinity on seed flotation of eight salt marsh species. Four of the eight species were tested for germination success under different stratification, salinity, and flooding conditions. Species were separated into two groups, four species received wet stratification and four dry stratification and fresh seeds of all species were tested for flotation and germination. Fresh seeds of seven out of eight species had flotation times independent of salinity, six of which had average flotation times of at least 50 d. Seeds of Spartina alterniflora and Spartina patens had the shortest flotation times, averaging 24 and 26 d, respectively. Following wet stratification, the flotation time of S. alterniflora seeds in higher salinity water (15 and 36 ppt) was reduced by over 75% and germination declined by more than 90%. Wet stratification reduced the flotation time of Distichlis spicata seeds in fresh water but increased seed germination from 2 to 16% in a fluctuating inundation regime. Fresh seeds of Iva frutescens and S. alternflora were capable of germination and therefore are non-dormant during dispersal. Fresh seeds of I. frutescens had similar germination to dry stratified seeds ranging 25-30%. Salinity reduced seed germination for all species except for S. alterniflora. A fluctuating inundation regime was important for seed germination of the low marsh species and for germination following cold stratification. The conditions that resulted in seeds sinking faster were similar to the conditions that resulted in higher germination for two of four species. ?? 2009 Elsevier B.V.
Aquatic Botany↗
Leaching of trace elements from Pittsburgh coal mill rejects compared with coal combustion products from a coal-fired power plant in Ohio, USA
We investigated the leachability of elements from mill rejects from the high-sulfur, bituminous Upper Pennsylvanian Pittsburgh coal, using the synthetic groundwater leaching procedure (SGLP), long-term leaching (LTL), and the U.S. Environmental Protection Agency's (EPA's) toxicity characteristic leaching procedure (TCLP), and compared their leaching behavior with that of three coal combustion products (CCPs)—bottom ash, economizer fly ash , and fly ash—from the same coal. None of the environmentally hazardous Resource Conservation and Recovery Act of 1976 (RCRA) metals analyzed in the leachates from the mill rejects or the CCPs exceeded U.S. EPA toxicity characteristics (As, Ba, Cd, Cr, Hg, Pb, and Se). Most trace elements leached the least from mill rejects and bottom ash and leached the most from fly ash. The elements Ca, Co, Mg, Mn, and Sr, however, were more concentrated in mill reject leachates than CCP leachates. Most trace elements increased in concentration with increasing SGLP and LTL leaching duration, but As and V decreased in concentration with time in mill reject leachates, suggesting sorption or precipitation of these elements was occurring.
Ohio↗
Multiple plant-community traits improve predictions of later-stage outcomes of restoration drill seedings: Implications for metrics of success
Success of ecological restoration is often only knowable if treatments meet criteria defined by biotic thresholds, but analytical frameworks to determine metrics of success and their underlying thresholds are needed. Early indicators of longer-term recovery trajectories are particularly critical where re-treatments may be required, such as in harsh climates or where repeated disturbances or invasive pressures prevail. We developed a framework for identifying which biotic traits would provide the best initial indication of longer-term target restoration goals and applied the framework to restoration drill-seedings of deep-rooted perennial bunchgrasses (DRPBGs) used to rehabilitate and restore semiarid rangelands threatened by exotic annual grasses (EAGs, e.g. cheatgrass) and the recurrent wildfire that EAGs cause. Initial traits measured included cover, basal diameter, height, and density (#plants/area) of DRPBGs and cover of EAGs and Sandberg bluegrass ( Poa secunda , POSE, a disturbance-adapted perennial). The longer-term target objective was ≥25 % DRPBG cover and ≤13 % EAG cover by the 5th year following drill-seedings. Measurements were made on 112 plots spanning 113,000 ha in sagebrush steppe on the Soda wildfire scar, in the Northern Great Basin, USA. Traits of DRPBGs tended to be uncorrelated with one another, thus each was informative in describing vegetation condition. Where DRPBG cover was initially >17 %, it tended to become >25 % by the 5th-year post-seeding. In plots that overcame an initial risk of not meeting the target objective (i.e. <17 % initial DRPBG cover), DRPBG tended be large DRPBGs (>22.8 cm height) and plots also had >7 % cover of POSE. Additional “sets” of initial vegetation traits were also predictive of longer-term restoration success or failure. Restoration drill-seeding of DRPBGs is a key but varied-outcome tool for breaking the exotic grass-fire cycle, and, contrary to a conventional tendency to rely on a limited number of mean traits such as % cover, a suite of biotic traits appears necessary to monitor to reliably know if trials are likely to yield success.
Ecological Indicators↗
Bioclimatic modeling of potential vegetation types as an alternative to species distribution models for projecting plant species shifts under changing climates
Land managers need new tools for planning novel futures due to climate change. Species distribution modeling (SDM) has been used extensively to predict future distributions of species under different climates, but their map products are often too coarse for fine-scale operational use. In this study we developed a flexible, efficient, and robust method for mapping current and future distributions and abundances of vegetation species and communities at the fine spatial resolutions that are germane to land management. First, we mapped Potential Vegetation Types (PVTs) using conventional statistical modeling techniques (Random Forests) that used bioclimatic ecosystem process and climate variables as predictors. We obtained over 50% accuracy across 13 mapped PVTs for our study area. We then applied future climate projections as climate input to the Random Forest model to generate future PVT maps, and used field data describing the occurrence of tree and non-tree species in each PVT category to model and map species distribution for current and future climate. These maps were then compared to two previous SDM mapping efforts with over 80% agreement and equivalent accuracy. Because PVTs represent the biophysical potential of the landscape to support vegetation communities as opposed to the vegetation that currently exists, they can be readily linked to climate forecasts and correlated with other, climate-sensitive ecological processes significant in land management, such as fire regimes and site productivity.
Montana↗
Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients
Rock-derived nutrients in soils originate from both local bedrock and atmospheric dust, including dust from far-distant sources. Distinction between fine particles derived from local bedrock and from dust provides better understanding of the landscape-scale distribution and abundance of soil nutrients. Sandy surficial deposits over dominantly sandstone substrates, covering vast upland areas of the central Colorado Plateau, typically contain 5-40% silt plus clay, depending on geomorphic setting and slope (excluding drainages and depressions). Aeolian dust in these deposits is indicated by the presence of titanium-bearing magnetite grains that are absent in the sedimentary rocks of the region. Thus, contents of far-traveled aeolian dust can be estimated from magnetic properties that primarily reflect magnetite content, such as isothermal remanent magnetization (IRM). Isothermal remanent magnetization was measured on bulk sediment samples taken along two transects in surficial sediment down gentle slopes away from sandstone headwalls. One transect was in undisturbed surficial sediment, the other in a setting that was grazed by domestic livestock until 1974. Calculation of far-traveled dust contents of the surficial deposits is based on measurements of the magnetic properties of rock, surficial deposits, and modern dust using a binary mixing model. At the undisturbed site, IRM-based calculations show a systematic down-slope increase in aeolian dust (ranging from 2% to 18% of the surface soil mass), similar to the down-slope increase in total fines (18-39% of surface soil mass). A combination of winnowing by wind during the past and down-slope movement of sediment likely accounts for the modern distribution of aeolian dust and associated nutrients. At the previously grazed site, dust also increases down slope (5-11%) in sediment with corresponding abundances of 13-25% fines. Estimates of the contributions of aeolian dust to the total soil nutrients range widely, depending on assumptions about grain-size partitioning of potential nutrients in weathered bedrock. Nevertheless, aeolian dust is important for this setting, contributing roughly 40-80% of the rock-derived nutrient stocks (P, K, Na, Mn, Zn, and Fe) in uppermost soil over most of the sampled slope at the undisturbed site, which shows no evidence of recent wind erosion.
Utah↗
Growth-suppressing and algicidal properties of an extract from Arundo donax, an invasive riparian plant, against Prymnesium parvum, an invasive harmful alga
This study examined the ability of acidic and neutral/alkaline fractions of a methanolic extract from giant reed ( Arundo donax ) and of two of its constituents, gramine and skatole, to inhibit growth of the ichthyotoxic golden alga (Prymnesium parvum ) in batch culture. For this study, growth suppression was defined as inhibition of maximum cell density, algicidal activity as early occurrence of negative growth, and algistatic activity as lack of net growth. The acidic fraction did not affect algal growth. The neutral/alkaline fraction showed growth-suppressing and algicidal activities but no signs of algistatic activity – namely, cells in cultures surviving a partial-algicidal exposure concentration (causing transient negative growth) were later able to initiate positive growth but at higher concentrations, algicidal activity was full and irreversible. Gramine suppressed growth more effectively than skatole and at the highest concentration tested, gramine also showed partial-algicidal and algistatic activity. While the partial-algicidal activities of the neutral/alkaline fraction and of gramine were short-lived (≤6 days) and thus may share similar mechanisms, algistatic activity was unique to gramine and persisted for >3 weeks. Given gramine’s reported concentration in the neutral/alkaline fraction, its corresponding level of algicidal activity is much lower than the fraction’s suggesting the latter contains additional potent algicides. Inhibition of maximum cell density by all test compounds was associated with reductions in exponential growth rate, and in the case of the neutral/alkaline fraction and gramine also reductions in early (pre-exponential) growth. These results indicate that giant reed is a potential source of natural products to control golden alga blooms. Giant reed is an invasive species in North America, thus also providing incentive for research into strategies to couple management efforts for both species.
Harmful Algae↗
Plant diversity shifts with drying and wetting cycles following removal of poplar plantations in Dongting Lake, China
Dongting Lake, the second largest lake in China, plays a crucial role in maintaining regional ecological security by providing key habitats for waterbirds. This study examined how hydrology and topography (ditches and mounds) together generate fine-scale wet–dry gradients that shape species establishment and successional trajectories. Over the past decade, vegetation restoration has been implemented through the removal of poplar plantations. We selected sites in West Dongting Lake representing different stages following poplar removal, including active plantations (Poplar), one-year (1Yr) and five-year (5Yr) restored sites, and natural floodplain reference sites. Analyses of seasonal water-level dynamics over several years revealed distinct hydrological regimes among restoration stages, with differences in inundation duration and amplitude corresponding to ditch–mound topography. Species diversity indicators showed that species richness was highest in Poplar (37 species) and lowest in Reference sites (14 species), with exotic species richness following the same trend. The lowest Cody index occurred between 1Yr and Reference sites, while the Jaccard similarity differed significantly among site pairs, with lower similarity observed in comparisons with the Reference site. Non-metric Multidimensional Scaling (NMDS) analysis indicated minimal overlap between Poplar and Reference sites, with 1Yr and 5Yr sites clustering together but remaining distinct from the Reference site. These results suggest that poplar cultivation and its associated mound-ditch topography have altered hydrological and community structure of the wetland, facilitating the persistence of exotic species. Natural recolonization is driven by the interaction between seasonal water-level dynamics and topography, which regulate inundation duration and wet–dry cycles. Effective restoration may require removal of poplar plantations and regrading of artificial ditches and mounds to restore natural hydrological connectivity to support vegetation recovery in these subtropical monsoonal wetlands.
Dongting Lake↗
Landsat time series analysis of fractional plant cover changes on abandoned energy development sites
Oil and natural gas development in the western United States has increased substantially in recent decades as technological advances like horizontal drilling and hydraulic fracturing have made extraction more commercially viable. Oil and gas pads are often developed for production, and then capped, reclaimed, and left to recover when no longer productive. Understanding the rates, controls, and degree of recovery of these reclaimed well sites to a state similar to pre-development conditions is critical for energy development and land management decision processes. Here we use a multi-decadal time series of satellite imagery (Landsat 5, 1984–2011) to assess vegetation regrowth on 365 abandoned well pads located across the Colorado Plateau in Utah, Colorado, and New Mexico. We developed high-frequency time series of the Soil-Adjusted Total Vegetation Index (SATVI) for each well pad using the Google Earth Engine cloud computing platform. BFAST time-series models were used to fit temporal trends, identifying when vegetation was cleared from the site and the magnitudes and rates of vegetation change after abandonment. The time series metrics are used to calculate the relative fractional vegetation cover (RFVC) of each pad, a measure of post-abandonment vegetation cover relative to pre-drilling condition. Mean and median RFVC were 36% (s.d. 33%) and 26%, respectively, five years after abandonment, with one third of well pads having RFVC greater than 50%. Statistical analyses suggest that much of the high vegetation cover is associated with weedy invasive annual species such as cheatgrass (Bromus tectorum) and Russian thistle (Salsola spp.). Climate conditions and the year of abandonment also play a role, with increased cover in later years associated with a wetter period. Non-linear change at many pads suggests longer recovery times than would be estimated by linear extrapolation. New techniques implemented here address a complex response of cover change to soils, management, and climate over time, and can be extended to the operational monitoring of energy development across large areas.
International Journal of Applied Earth Observation↗
Landscape-scale processes influence riparian plant composition along a regulated river
Hierarchical frameworks are useful constructs when exploring landscape- and local-scale factors affecting patterns of vegetation in riparian areas. In drylands, which have steep environmental gradients and high habitat heterogeneity, landscape-scale variables, such as climate, can change rapidly along a river's course, affecting the relative influence of environmental variables at different scales. To assess how landscape-scale factors change the structure of riparian vegetation, we measured riparian vegetation composition along the Colorado River through Grand Canyon, determined which factors best explain observed changes, identified how richness and functional diversity vary, and described the implications of our results for river management. Cluster analysis identified three divergent floristic groups that are distributed longitudinally along the river. These groups were distributed along gradients of elevation, temperature and seasonal precipitation, but were not associated with annual precipitation or local-scale factors. Species richness and functional diversity decreased as a function of distance downstream showing that changing landscape-scale factors result in changes to ecosystem characteristics. Species composition and distribution remain closely linked to seasonal precipitation and temperature. These patterns in floristic composition in a semiarid system inform management and provide insights into potential future changes as a result of shifts in climate and changes in flow management.
Arizona↗
Weed-suppressive bacteria have no effect on exotic or native plants in sagebrush-steppe
Approaches and techniques for control of exotic annual grasses are a high priority in rangelands including sagebrush steppe. Strains of the soil bacterium Pseudomonas fluorescens have been proposed to be selectively pathogenic to multiple species of exotic annual grasses (“Pf,” weed-suppressive bacteria, “WSB”). However, defensible tests of the target and nontarget effects of these WSB strains in the field are needed. We evaluated the effects of D7 and MB906 strains of Pf WSB in sagebrush steppe invaded by cheatgrass ( Bromus tectorum L), medusahead ( Taeniatherum caput-medusae L. Nevski), and other exotic annual grasses. We evaluated the WSB strains with and without herbicides (imazapic, rimsulfuron) or discing to mix surface-spray of the WSB into deeper soils, and we replicated these tests in three ecoregions that differed in soils and climate. Over 3 yr after treatment, neither WSB strain affected cover of exotic annual grasses, perennial bunchgrasses, or the total community, either with WSB alone or in combination with herbicides or discing. WSB has received considerable attention and is being applied across large rangeland areas, but the WSB strains and methods applied here were ineffective. We recommend any future use of WSB be applied in an experimental fashion, with experimental design and measurement of responses, until its effects can be proven.
Rangeland Ecology & Management↗
Response to comment on “Persistence of pharmaceutical compounds and other organic wastewater contaminants in a conventional drinking-water-treatment plant”
The U.S. Geological Survey (USGS) and the Centers for Disease Control thank Dr. Till for her comments concerning our research ( Till, 2005 ) and welcome the opportunity to respond. The primary objective of our study was to evaluate the potential for organic wastewater-related contaminants (OWCs), including pharmaceuticals, to survive a conventional drinking-water-treatment process and persist in potable-water supplies ( Stackelberg et al., 2004 ). Our study was supported by two USGS laboratories: the National Water Quality Laboratory (NWQL), which provided the HPLC/ESI-MS and CLLE GC/MS data and the Ocala Water Quality and Research Laboratory (OWQRL), which provided the LC/MS data ( Stackelberg et al., 2004 ). Although discussed as distinct techniques by Dr. Till and indicated by differing acronyms to distinguish the laboratories producing the data, as described in our paper, the two LC/MS methods are very similar; they consist of a solid-phase extraction method with analysis of the extract produced using high-performance liquid chromatography coupled to an electrospray ionization mass spectrometer operated in the positive mode. The NWQL and OWQRL report ‘trace’ and ‘ultratrace’ determinations of analytes that provide significant benefit for describing the presence and fate of low-level contaminants. For mass spectral methods, an analyte is qualitatively identified by its retention time on the chromatographic column as well as the presence of two or more confirming ions with area ratios that match that of the reference standard compounds. Because of a recognized increased risk of false positives, these qualitative identification criteria are used in conjunction with abundant quality-control samples (detailed below) to confirm detection prior to making an estimate of the concentration. These qualitative identification criteria must be met before a compound is considered present (or detected) in a sample ( Oblinger Childress et al., 1999 ). When a compound has been qualitatively identified in an environmental sample (whether above or below its reporting level [RL]), it is assessed in context with associated field and laboratory blanks, field and laboratory replicates, and other data, such as appropriate laboratory reagent spikes. An environmental concentration is calculated only after determining that field and laboratory procedures did not contaminate the samples. The concentrations are then calculated from 5- to 8-point calibration curves using internal standard quantitation. Our lowest calibration standard is intentionally much lower than the RL, typically 10 times lower. The most abundant molecular or fragment ion is used for quantitation, and, for the two LC/MS methods, at least one, and where possible two, qualifier ions are used for confirmation. For the GC/MS method, with its greater degree of fragmentation, one quantitation and two qualifier ions are used. When any of the abovementioned qualitative identification criteria are not met, the analyte is considered not present and is reported as “less than” the RL.
Science of the Total Environment↗