Savannah River National Laboratory

As the human population grows and natural resources decline, there is pressure to apply increasing levels of top‐down, command‐and‐control management to natural resources. This is manifested in attempts to control ecosystems and in socioeconomic institutions that respond to erratic or surprising ecosystem behavior with more control. Command and control, however, usually results in unforeseen consequences for both natural ecosystems and human welfare in the form of collapsing resources, social and economic strife, and losses of biological diversity. We describe the “pathology of natural resource management,” defined as a loss of system resilience when the range of natural variation in the system is reduced encapsulates the unsustainable environmental, social, and economic outcomes of command‐and‐control resource management. If natural levels of variation in system behavior are reduced through command‐and‐control, then the system becomes less resilient to external perturbations, resulting in crises and surprises. We provide several examples of this pathology in management. An ultimate pathology emerges when resource management agencies, through initial success with command and control, lose sight of their original purposes, eliminate research and monitoring, and focus on efficiency of control. They then become isolated from the managed systems and inflexible in structure. Simultaneously, through overcapitalization, society becomes dependent upon command and control, demands it in greater intensity, and ignores the underlying ecological change or collapse that is developing. Solutions to this pathology cannot come from further command and control (regulations) but must come from innovative approaches involving incentives leading to more resilient ecosystems, more flexible agencies, more self‐reliant industries, and a more knowledgeable citizenry. We discuss several aspects of ecosystem pattern and dynamics at large scales that provide insight into ecosystem resilience, and we propose a “Golden Rule” of natural resource management that we believe is necessary for sustainability: management should strive to retain critical types and ranges of natural variation in resource systems in order to maintain their resiliency.

Fresh fracture surfaces of the martian meteorite ALH84001 contain abundant polycyclic aromatic hydrocarbons (PAHs). These fresh fracture surfaces also display carbonate globules. Contamination studies suggest that the PAHs are indigenous to the meteorite. High-resolution scanning and transmission electron microscopy study of surface textures and internal structures of selected carbonate globules show that the globules contain fine-grained, secondary phases of single-domain magnetite and Fe-sulfides. The carbonate globules are similar in texture and size to some terrestrial bacterially induced carbonate precipitates. Although inorganic formation is possible, formation of the globules by biogenic processes could explain many of the observed features, including the PAHs. The PAHs, the carbonate globules, and their associated secondary mineral phases and textures could thus be fossil remains of a past martian biota.

Abstract The impact of mining and smelting of metal ores on environmental quality is described. Mines produce large amounts of waste because the ore is only a small fraction of the total volume of the mined material. In the metal industry, production of Cu, Pb, and Zn causes the greatest degradation of the environment. Copper mining produces extensive mine wastes and tailings and Cu smelting emits approximately 0.11 Mg of S per Mg of Cu produced in the USA. Zinc and Pb smelters release large quantities of Cd and Pb into the environment. Metal smelting and refining produce gaseous (CO 2 , SO 2 , NO x , etc.) and particulate matter emissions, sewage waters , and solid wastes . Soil contamination with trace metals is considered a serious problem related to smelting; however, mining and smelting are not main sources of global metal input into soils. Other sources like discarded manufactured products, coal ash, agriculture, and transportation take a lead. Smelters are the main sources of atmospheric emissions of As, Cu, Cd, Sb, and Zn on a global scale and they contribute substantially to the overall emissions of Cr, Pb, Se, and Ni. A quantitative evaluation of the environmental health effects of mining and smelting is difficult because of the complexity of factors involved and lack of consistent methodology. Nevertheless, the case studies described indicate that negative health effects could arise from Pb mining and smelting. Risk assessment revealed that food chain contamination by Cd from soils contaminated by smelting is very unlikely under the western diet.

Abstract A major shift to coal as an energy source adjunct with more stringent air quality standards will result in the increasing production of vast quantities of the already difficult‐to‐dispose coal residues in the United States. Since coal residues contain potentially hazardous substances, improper handling and disposal could cause undesirable environmental effects. This report intends to summarize impacts of land‐oriented utilization and disposal of various coal combustion residues. The physical and chemical properties of coal ashes are dependent on the coal's geological origin, combustion conditions, efficiency of particulate removal, and degree of weathering before final disposal. Coal residues, applied on cropland, are not practical sources of essential plant nutrients N, P, and K; however, they can effectively serve as a supplementary supply of Ca, S, B, Mo, and Se to soils. Fly ash could also be an effective amendment in neutralizing soil acidity. Many of the observed chemical and biological effects of fly ash applications to soils resulted from the increased activities of Ca 2+ and OH − ions. Most unweathered fly ashes, especially those coming from the subbituminous and lignite coals of the western U.S., are high in these constituents and usually will cause high soil salinity. The accumulation of B, Mo, Se, and soluble salts in fly ash‐amended soils appear to be the most serious constraints associated with land application of fly ash to soil.

Reports of declining amphibian populations in many parts of the world are numerous, but supporting long-term census data are generally unavailable. Census data from 1979 to 1990 for three salamander species and one frog species at a breeding pond in South Carolina showed fluctuations of substantial magnitude in both the size of breeding populations and in recruitment of juveniles. Breeding population sizes exhibited no overall trend in three species and increased in the fourth. Recent droughts account satisfactorily for an increase in recruitment failures. These data illustrate that to distinguish between natural population fluctuations and declines with anthropogenic causes may require long-term studies.

Almost half of the total organic carbon (C) in terrestrial ecosystems is stored in forest soils. By altering rates of input or release of C from soils, forest management activities can influence soil C stocks in forests. In this review, we synthesize current evidence regarding the influences of 13 common forest management practices on forest soil C stocks. Afforestation of former croplands generally increases soil C stocks, whereas on former grasslands and peatlands, soil C stocks are unchanged or even reduced following afforestation. The conversion of primary forests to secondary forests generally reduces soil C stocks, particularly if the land is converted to an agricultural land-use prior to reforestation. Harvesting, particularly clear-cut harvesting, generally results in a reduction in soil C stocks, particularly in the forest floor and upper mineral soil. Removal of residues by harvesting whole-trees and stumps negatively affects soil C stocks. Soil disturbance from site preparation decreases soil C stocks, particularly in the organic top soil, however improved growth of tree seedlings may outweigh soil C losses over a rotation. Nitrogen (N) addition has an overall positive effect on soil C stocks across a wide range of forest ecosystems. Likewise, higher stocks and faster accumulation of soil C occur under tree species with N-fixing associates. Stocks and accumulation rates of soil C also differ under different tree species, with coniferous species accumulating more C in the forest floor and broadleaved species tending to store more C in the mineral soil. There is some evidence that increased tree species diversity could positively affect soil C stocks in temperate and subtropical forests, but tree species identity, particularly N-fixing species, seems to have a stronger impact on soil C stocks than tree species diversity. Management of stand density and thinning have small effects on forest soil C stocks. In forests with high populations of ungulate herbivores, reduction in herbivory levels can increase soil C stocks. Removal of plant biomass for fodder and fuel is related to a reduction in the soil C stocks. Fire management practices such as prescribed burning reduce soil C stocks, but less so than wildfires which are more intense. For each practice, we identify existing gaps in knowledge and suggest research to address the gaps.

Matrix population models require the population to be divided into discrete stage classes. In many cases, especially when classes are defined by a continuous variable, such as length or mass, there are no natural breakpoints, and the division is artificial. We introduce the “integral projection model,” which eliminates the need for division into discrete classes, without requiring any additional biological assumptions. Like a traditional matrix model, the integral projection model provides estimates of the asymptotic growth rate, stable size distribution, reproductive values, and sensitivities of the growth rate to changes in vital rates. However, where the matrix model represents the size distributions, reproductive value, and sensitivities as step functions (constant within a stage class), the integral projection model yields smooth curves for each of these as a function of individual size. We describe a method for fitting the model to data, and we apply this method to data on an endangered plant species, northern monkshood (Aconitum noveboracense), with individuals classified by stem diameter. The matrix and integral models yield similar estimates of the asymptotic growth rate, but the reproductive values and sensitivities in the matrix model are sensitive to the choice of stage classes. The integral projection model avoids this problem and yields size-specific sensitivities that are not affected by stage duration. These general properties of the integral projection model will make it advantageous for other populations where there is no natural division of individuals into stage classes.

The ecological forces determining where within a landscape plants recruit and grow has been termed proximal habitat choice. Habitat choice is imposed first by a heterogeneous pattern of seed dispersal across the patches that make up the landscape and second by environmental variation that favors plant survival in some patches more than in others. Seed‐seedling conflicts can occur during both of these phases of habitat choice if conditions or traits that are favorable for seeds are unfavorable for seedlings. During the dispersal phase, smaller seeds may have a greater probability of dispersal than larger seeds, and thus a greater probability of escape from predation, but they contain fewer reserves for support of the establishing seedling. After dispersal, environmental characteristics of a given patch type that lead to disproportionately high seed survival may lead to disproportionately low seedling survival. Considering three hypothetical landscapes, each composed of five patch types, I demonstrate that seed‐seedling conflicts can have a major impact on both the overall quantity of recruitment at the landscape level and on the distribution of recruitment among patches. Available empirical evidence suggests these conflicts may be widespread in natural systems. Given their potential importance and extent, seed‐seedling conflicts may play a previously unrecognized role in habitat choice.

Abstract: A study of Blanding's turtles conducted during 27 of the last 37 years provided demographic data sufficient to examine how life‐history characteristics may constrain population responses of long‐lived organisms. Eight independent estimates of annual adult survivorship exceeded 93%. Nest survival was variable and ranged from 0.0 to 63% annually, with a mean of 44% from 1976 to 1984 and 3.3% from 1985 to 1991. Recruitment of juveniles and adults was sufficient to replace individuals estimated to have died during the study. A life table for the population resulted in a cohort generation time of 37 years and required a 72% annual survivorship of juveniles between 1 and 13 years of age to maintain a stable population. Population stability was most sensitive to changes in adult or juvenile survival and less sensitive to changes in age at sexual maturity, nest survival, or fecundity. The results from the present study indicate that life‐history traits of long‐lived organisms consist of co‐evolved traits that result in severe constraints on the ability of populations to respond to chronic disturbances. Successful management and conservation programs for long‐lived organisms will be those that recognize that protection of all life stages is necessary. Programs such as headstarting or protection only of nesting sites, in the absence of programs to reduce mortality of older juveniles and adults, appear to be less than adequate to save long‐lived organisms such as sea turtles and some tortoises. The concept of sustainable harvest of already‐reduced populations of long‐lived organisms appears to be an oxymoron.

Previous studies of sexual size dimorphism (SSD) use a variety of size dimorphism indices (SDI's) to quantify SSD. We propose that a useful SDI should meet four criteria as follows; 1) it should be properly scaled, 2) it should have high intuitive value, 3) it should produce values with one sign, (positive) when sex A is larger than sex B, and the opposite sign when sex B is larger, and 4) it should produce values that are symmetric around a central value, preferably zero. Many previously published SDI's do not meet any of these criteria, and none meet more than three. We present an alternative SDI based on the mean size of the larger sex divided by the mean size of the smaller sex with the result arbitrarily defined as positive (minus one) when females are larger and negative (plus one) in the converse case. Careful selection of a primary size variable is crucial to meaningful interpretation of sexual size differences.

The association of endophytic bacteria with their plant hosts has a beneficial effect for many different plant species. Our goal is to identify endophytic bacteria that improve the biomass production and the carbon sequestration potential of poplar trees (Populus spp.) when grown in marginal soil and to gain an insight in the mechanisms underlying plant growth promotion. Members of the Gammaproteobacteria dominated a collection of 78 bacterial endophytes isolated from poplar and willow trees. As representatives for the dominant genera of endophytic gammaproteobacteria, we selected Enterobacter sp. strain 638, Stenotrophomonas maltophilia R551-3, Pseudomonas putida W619, and Serratia proteamaculans 568 for genome sequencing and analysis of their plant growth-promoting effects, including root development. Derivatives of these endophytes, labeled with gfp, were also used to study the colonization of their poplar hosts. In greenhouse studies, poplar cuttings (Populus deltoides x Populus nigra DN-34) inoculated with Enterobacter sp. strain 638 repeatedly showed the highest increase in biomass production compared to cuttings of noninoculated control plants. Sequence data combined with the analysis of their metabolic properties resulted in the identification of many putative mechanisms, including carbon source utilization, that help these endophytes to thrive within a plant environment and to potentially affect the growth and development of their plant hosts. Understanding the interactions between endophytic bacteria and their host plants should ultimately result in the design of strategies for improved poplar biomass production on marginal soils as a feedstock for biofuels.

SYNOPSIS. A study of common snapping turtles conducted from 1975 through 1992 in southeastern Michigan provided sufficient demographic data to examine how life history characteristics may constrain population responses of long-lived organisms. Females reached sexual maturity between 11 and 16 years of age. Minimum reproductive frequency was less than annual (0.85), and nest survivorship over 17 years ranged from 0 to 64% and averaged 23%. Survivorship of yearlings had to be estimated since hatchlings can pass through the mesh on traps. Actual survivorship of juveniles was over 0.65 by age 2 and averaged 0.77 between the ages of 2 and 12 years. Annual survivorship of adult females ranged from 0.88 to 0.97. A life table for the population resulted in a cohort generation time of 25 years. Population stability was most sensitive to changes in adult or juvenile survival, and less sensitive to changes in age at sexual maturity, nest survival or fecundity. An increase in annual mortality of 0.1 on adults over 15 years of age with no density-dependent compensation would halve the number of adults in less than 20 years. The results from the present study indicate that life history traits of long-lived organisms consist of co-evolved traits that severely constrain the ability of populations to respond to chronic disturbances. Successful management and conservation programs for long-lived organisms will be those that recognize that protection of all life stages is necessary. Without protection of adults and older juveniles, programs that protect nests and headstart hatchlings have a low probability of success. Carefully managed sport harvests of turtles or other long-lived organisms may be sustainable; however, commercial harvests will certainly cause substantial population declines

Nations using borosilicate glass as an immobilization material for radioactive waste have reinforced the importance of scientific collaboration to obtain a consensus on the mechanisms controlling the long-term dissolution rate of glass. This goal is deemed to be crucial for the development of reliable performance assessment models for geological disposal. The collaborating laboratories all conduct fundamental and/or applied research using modern materials science techniques. This paper briefly reviews the radioactive waste vitrification programs of the six participant nations and summarizes the current state of glass corrosion science, emphasizing the common scientific needs and justifications for on-going initiatives.

Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species.

Abstract Motion‐activated cameras (“camera traps”) are increasingly used in ecological and management studies for remotely observing wildlife and are amongst the most powerful tools for wildlife research. However, studies involving camera traps result in millions of images that need to be analysed, typically by visually observing each image, in order to extract data that can be used in ecological analyses. We trained machine learning models using convolutional neural networks with the ResNet‐18 architecture and 3,367,383 images to automatically classify wildlife species from camera trap images obtained from five states across the United States. We tested our model on an independent subset of images not seen during training from the United States and on an out‐of‐sample (or “out‐of‐distribution” in the machine learning literature) dataset of ungulate images from Canada. We also tested the ability of our model to distinguish empty images from those with animals in another out‐of‐sample dataset from Tanzania, containing a faunal community that was novel to the model. The trained model classified approximately 2,000 images per minute on a laptop computer with 16 gigabytes of RAM. The trained model achieved 98% accuracy at identifying species in the United States, the highest accuracy of such a model to date. Out‐of‐sample validation from Canada achieved 82% accuracy and correctly identified 94% of images containing an animal in the dataset from Tanzania. We provide an r package (Machine Learning for Wildlife Image Classification) that allows the users to (a) use the trained model presented here and (b) train their own model using classified images of wildlife from their studies. The use of machine learning to rapidly and accurately classify wildlife in camera trap images can facilitate non‐invasive sampling designs in ecological studies by reducing the burden of manually analysing images. Our r package makes these methods accessible to ecologists.

Low levels of allozyme heterozygosity in populations are often attributed to previous population bottlenecks; however, few experiments have examined the relationship between heterozygosity and bottlenecks under natural conditions. The composition and number of founders of 55 experimental populations of the eastern mosquitofish (Gambusia holbrooki), maintained under simulated field conditions, were manipulated to examine the effects of bottlenecks on three components of allozyme diversity. Correlations between observed and expected values of allozyme heterozygosity, proportions of polymorphic loci, and numbers of alleles per locus were 0.423, 0.602, and 0.772, respectively. The numbers of polymorphic loci and of alleles per locus were more sensitive indicators of differences in genetic diversity between the pre-bottleneck and post-bottleneck populations than was multiple-locus heterozygosity. In many populations, single- and multiple-locus heterozygosity actually increased as a result of the founder event. The weak relationship between a population's heterozygosity and the number and composition of its founders resulted from an increase in the variance of heterozygosity due to drift of allele frequencies. There was little evidence that selection influenced the loss of allozyme variation. When it is not possible to estimate heterozygosity at a large number of polymorphic loci, allozyme surveys attempting to detect founder events and other types of bottlenecks should focus on levels of locus polymorphism and allelic diversity rather than on heterozygosity.

This chapter discusses the influence of hydroxy-AI interlayer components on the cation exchange capacity of smectites and vermiculites. Hydroxy-AI interlayered smectite and vermiculite are thought to occur in soils as either weathering products derived from chlorite weathering or more commonly from the deposition of hydroxy-AI polymeric components within the interlayer spaces of these expansible or limited expansible layer silicates. Structural breakdown of the chlorite crystals is associated with the weight loss upon heating as well as with significant changes in infrared spectra. One approach to the identification of chlorites is an evaluation of their chemical stability or equilibria properties, so that one may differentiate chlorites from hydroxy-interlayered clays. Polymeric hydroxy-AI components significantly modify the physicochemical properties of soil minerals. The interlayer hydroxide material of chlorite and the hydroxy-inter-layer material of hydroxy-interlayered smectite and/or vermiculite appear to be chemically distinct. Differences in stability of the laboratory-synthesized hydroxy interlayers have been reported.

Of the 356 species of turtles worldwide, approximately 61% are threatened or already extinct. Turtles are among the most threatened of the major groups of vertebrates, in general, more so than birds, mammals, fishes or even the much besieged amphibians. Reasons for the dire situation of turtles worldwide include the familiar list of impacts to other species including habitat destruction, unsustainable overexploitation for pets and food, and climate change (many turtles have environmental sex determination). Two notable characteristics of pre-Anthropocene turtles were their massive population sizes and correspondingly high biomasses, the latter among the highest values (over 855 kilograms per hectare) ever reported for animals. As a result of their numerical dominance, turtles have played important roles as significant bioturbators of soils, infaunal miners of sea floors, dispersers and germination enhancers of seeds, nutrient cyclers, and consumers. The collapse of turtle populations on a global scale has greatly diminished their ecological roles.

Differences in methylmercury (CH(3)Hg) production normalized to the sulfate reduction rate (SRR) in various species of sulfate-reducing bacteria (SRB) were quantified in pure cultures and in marine sediment slurries in order to determine if SRB strains which differ phylogenetically methylate mercury (Hg) at similar rates. Cultures representing five genera of the SRB (Desulfovibrio desulfuricans, Desulfobulbus propionicus, Desulfococcus multivorans, Desulfobacter sp. strain BG-8, and Desulfobacterium sp. strain BG-33) were grown in a strictly anoxic, minimal medium that received a dose of inorganic Hg 120 h after inoculation. The mercury methylation rates (MMR) normalized per cell were up to 3 orders of magnitude higher in pure cultures of members of SRB groups capable of acetate utilization (e.g., the family Desulfobacteriaceae) than in pure cultures of members of groups that are not able to use acetate (e.g., the family Desulfovibrionaceae). Little or no Hg methylation was observed in cultures of Desulfobacterium or Desulfovibrio strains in the absence of sulfate, indicating that Hg methylation was coupled to respiration in these strains. Mercury methylation, sulfate reduction, and the identities of sulfate-reducing bacteria in marine sediment slurries were also studied. Sulfate-reducing consortia were identified by using group-specific oligonucleotide probes that targeted the 16S rRNA molecule. Acetate-amended slurries, which were dominated by members of the Desulfobacterium and Desulfobacter groups, exhibited a pronounced ability to methylate Hg when the MMR were normalized to the SRR, while lactate-amended and control slurries had normalized MMR that were not statistically different. Collectively, the results of pure-culture and amended-sediment experiments suggest that members of the family Desulfobacteriaceae have a greater potential to methylate Hg than members of the family Desulfovibrionaceae have when the MMR are normalized to the SRR. Hg methylation potential may be related to genetic composition and/or carbon metabolism in the SRB. Furthermore, we found that in marine sediments that are rich in organic matter and dissolved sulfide rapid CH(3)Hg accumulation is coupled to rapid sulfate reduction. The observations described above have broad implications for understanding the control of CH(3)Hg formation and for developing remediation strategies for Hg-contaminated sediments.

Abstract: Wetland development within the United States is regulated primarily by size. Decisions concerning wetland destruction or conservation are therefore based in part on three inherent assumptions: (1) small wetlands contain water for short portions of the year; (2) small wetlands support few species; and (3) species found in small wetlands are also found in larger wetlands. We tested these assumptions using data on wetland size, relative hydroperiod (drying scores), and relative species richness of amphibians in depression wetlands of the southeastern United States. We found a significant (p = 0.03) but weak (r 2 = 0.05) relationship between hydroperiod and wetland size and no relationship (p = 0.48) between amphibian species richness and wetland size. Furthermore, synthetic models of lentic communities predict that short‐hydroperiod wetlands support a unique group of species. Empirical investigations support this prediction. Our results indicate that hydroperiod length should be included as a primary criterion in wetland regulations. We advocate a landscape approach to wetlands regulation, focused in part on conserving a diversity of wetlands that represent the entire hydroperiod gradient.