Search

Analysis of charcoal particles preserved in lake sediments has been frequently used to reconstruct fire, vegetation and climate history. Larger macroscopic particles (>125 μm) are attributed to local fires, whereas microscopic charcoal particles (<125 μm), observed on pollen slides, are a signal of regional fire. Taxonomic identification of the charcoal particles adds to the fire-history reconstruction by providing information about fuel composition and past fire conditions. Identification of charcoal can unravel one of the longstanding questions regarding past fire regimes, namely what was burning. This paper describes an analysis of charcoal particles preserved in the sediments of a small closed-basin lake in Yellowstone National Park. Blacktail Pond (44.954°N, 110.604°W; 2012 m elev) is located in steppe vegetation surrounded by conifer forest. Previous studies of the site have presented a multi-proxy environmental history of the last 14,650 years. The focus of this investigation was on the fire history of the early-Holocene (11,500–9900 cal yr BP). Thirty-nine sediment samples were taken at 0.5 cm intervals to examine macroscopic charcoal particles, with attention on two large charcoal peaks at 10,970 and 10,200 cal yr BP that registered large or near-site fires. Twenty-eight samples contained 243 large-enough particles (180–250 μm) to be examined with scanning electron microscopy. We were able to identify charcoal of conifers (Pinus , Picea, and Abies or Juniperus), Artemisia and unidentified deciduous shrubs, and unidentified monocotyledons. The first fire burned a mixture of fuels, whereas the second episode burned Artemisia , shrubs and herbs but no conifers. The results are consistent with previous pollen interpretations at Blacktail Pond that indicate an open mixed-conifer forest in the early Holocene prior to 10,750 cal yr BP, replaced by Pinus contorta forest on the slopes and steppe in the valley. The relative dominance of Pinus contorta -type charcoal points to the importance of fire as a catalyst for the spread of this species. [ABSTRACT FROM AUTHOR]

This paper describes the image acquisition and processing methodology, including surface emissivity and atmospheric corrections, for generating surface temperatures of two active hydrothermal systems in Yellowstone National Park. Airborne thermal infrared (8–12 μm) images were obtained annually from 2007 to 2012 using a FLIR SC640 thermal infrared camera system. Thermal infrared image acquisitions occurred under clear-sky conditions after sunset to meet the objective of providing high-spatial resolution, georectified imagery for hydrothermal monitoring. Comparisons of corrected radiative temperature maps with measured ground and water kinetic temperatures at flight times provided an assessment of temperature accuracy. A repeatable, time-sequence of images for Hot Spring Basin (2007–2012) and Norris Geyser Basin (2008–2012) documented fracture-related changes in temperature and fluid flow for both hydrothermal systems, highlighting the utility of methods for synoptic monitoring of Yellowstone National Park's hydrothermal systems. [ABSTRACT FROM AUTHOR]

• Recovery of aspen in Yellowstone National Park could be shaped by multi-scalar trophic cascade reversals driven by the reintroduction of grey wolves (Beschta et al., 2018). • Such strong conclusions require supporting evidence of the proposed operating mechanisms driving multi-scalar trophic cascade reversals, but no measurements of these processes were provided in Beschta et al. (2018). • The Beschta et al. (2018) study was also psuedoreplicated in space and unreplicated in time, denying them the strong inference required to draw such strong conclusions about ecosystem processes. • Could publishing ecologists please refrain from making claims that are exaggerated beyond the certainty of their methods? Recently Beschta et al. (2018) published a paper proposing that recovery of aspen in Yellowstone National Park was shaped by multi-scalar trophic cascade reversals driven by the reintroduction of grey wolves. Although this conclusion is one possibility, and might help explain what was observed, the paper of itself provides neither adequate evidence or inference to draw such firm conclusions. Most importantly, the suggested operands driving trophic cascade reversals, i.e. 'human shielding', and consequent altered elk and wolf activity patterns and densities, were unmeasured, and there was no replication in either space or time of those measurements that were made. Ecology and its associated ecosystem management are not well-served by claims about ecological processes and mechanisms that are unsupported by the presented evidence. [ABSTRACT FROM AUTHOR]

Abstract: The Coarse Woody Debris (CWD) quantity, defined as biomass per unit area (t/ha), and the quality, defined as the proportion of standing dead logs to the total CWD quantity, greatly contribute to many ecological processes such as forest nutrient cycling, tree regeneration, wildlife habitat, fire dynamics, and carbon dynamics. However, a cost-effective and time-saving method to determine CWD is not available. Very limited literature could be found that applies remote sensing technique to CWD inventory. In this paper, we fused the wall-to-wall multi-frequency and multi-polarization Airborne Synthetic Aperture Radar (AirSAR) and optical Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) to estimate the quantity and quality of CWD in Yellowstone post-fire forest ecosystem, where the severe 1988 fire event resulted in high spatial heterogeneity of dead logs. To relate backscatter values to CWD metrics, we first reduced the terrain effect to remove the interference of topography on AirSAR backscatter. Secondly, we removed the influence of regenerating sapling by quadratic polynomial fitting between AVIRIS Enhanced Vegetation Index (EVI) and different channels backscatters. The quantity of CWD was derived from P hh and P hv, and the quality of CWD was derived from P hh aided by the ratio of L hv and P hh. Two maps of Yellowstone post-fire CWD quantity and quality were produced. The calculated CWD quantity and quality were validated by extensive field surveys. Regarding CWD quantity, the correlation coefficient between measured and predicted CWD is only 0.54 with mean absolute error up to 29.1 t/ha. However, if the CWD quantity was discretely classified into three categories of “≤60”, “60–120”, and “≥120”, the overall accuracy is 65.6%; if classified into two categories of “≤90” and “≥90”, the overall accuracy is 73.1%; if classified into two categories of “≤60” and “≥60”, the overall accuracy is 84.9%. This indicates our attempt to map CWD quantity spatially and continuously achieved partial success; however, the general and discrete categories are reasonable. Regarding CWD quality, the overall accuracy of 5 types (Type 1—standing CWD ratio ≥40%; Type 2—15%≤standing CWD ratio <40%; Type 3—7%≤standing CWD ratio<15%; Type 4—3%≤standing CWD ratio <7%; Type 5—standing CWD ratio <3%) is only 40.32%. However, when type 1, 2, 3 are combined into one category and type 4 and 5 are combined into one category, the overall accuracy is 67.74%. This indicates the partial success of our initial results to map CWD quality into detailed categories, but the result is acceptable if solely very coarse CWD quality is considered. Bias can be attributed to the complex influence of many factors, such as field survey error, sapling compensation, terrain effect reduction, surface properties, and backscatter mechanism understanding. [Copyright &y& Elsevier]

Many of the habitats and resources which influence ecological functioning within National Parks, and protected areas in general, are located outside of their borders in unprotected areas. Hence, land use and land cover changes in surrounding areas may substantially influence the natural resources within parks. The US National Park Service has recognized these threats and incorporated land use and land cover monitoring into its Inventory and Monitoring Program. The purpose of this paper is to provide a framework based on a conceptual approach for planning and implementing monitoring within this Program. We present a conceptual model, based on ecological theory, which illustrates how land use and land cover change impact park resources, and helps to identify monitoring indicators that will measure relevant attributes of land use and land cover change. We also discuss potential sources of data for quantifying indicators of land use and land cover change over time, including remote sensing data and ancillary spatial datasets. Finally, we describe steps for analyzing monitoring data so that the intensity and direction of changes in land use and land cover over time are quantified, as well as trends in the status of important park resources impacted by these changes. Integration of land use and land cover monitoring data and park resource data will allow for analysis of change from past to present, and can be used to project trends into the future to provide knowledge about potential land use and land cover change scenarios and ecological impacts. We illustrate our monitoring approach with an example from the Inventory and Monitoring Program''s Greater Yellowstone Network. [Copyright &y& Elsevier]

We describe a new effort to date hydrothermal silica sinter deposits (geyserite) from the Upper Geyser Basin of Yellowstone National Park using 14C of co-deposited organic matter, U-series and cosmogenic 10Be methods. A majority of the samples were collected from stratigraphic sections, mainly at Riverside, Giant, and Castle Geysers. Ages obtained from 41 14C analyses range from modern to 12.1 cal ka BP. Nearly all the 14C ages show inconsistencies with their stratigraphic positions, and several replicate 14C analyses from the same sample result in significantly different ages. The δ13C values of the organic material in the sinter range from −26.6‰ to −12.7‰. The more enriched values are attributed to microbial fixation of dissolved inorganic carbon (DIC), which has heavier δ13C values and is 14C-depleted relative to atmospheric CO 2 , leading to an apparent older age. U-series analyses on 4 samples yielded ages between 2.2 and 7.4 ka. Large 230Th/U age uncertainties in the sinter, due to low uranium concentrations along with elevated 232Th and associated initial 230Th, make these ages imprecise for use on Holocene deposits. A single cosmogenic 10Be exposure age of 596 ± 18 ka is considerably older than the age of underlying rhyolite and is thus unreliable. This apparent old age results from contamination by meteoric 10Be trapped in the opal that overprints the very small amount of cosmogenic 10Be. By presenting the problems we encountered and discussing their probable cause, this paper highlights the difficulty in obtaining reliable, high-precision geochronological data necessary to use sinter deposits as paleoenvironmental and paleo-hydrothermal archives. • We identify challenges in determining reliable ages of hydrothermal sinter deposits. • We apply radiocarbon, uranium-series and cosmogenic beryllium dating methods. • Radiocarbon ages can be biased by microbial fixation of dissolved inorganic carbon. • Uranium-series uncertainties are too large for precise dating of Holocene sinter. • Beryllium-10 exposure ages cannot be used for dating sinter from the Holocene. [ABSTRACT FROM AUTHOR]

This paper uses a spatial predator-prey model to provide insights into the complex and politically charged management of species recently removed from the federal endangered species list. The model is motivated by the recently delisted gray wolf with spatiotemporal dynamics between elk, wolves, hunters, cattle ranchers, and the tourism industry in the Greater Yellowstone Ecosystem. State wildlife managers set hunting rates for elk and wolves to maximize the discounted net benefits from tourism, hunting, cattle grazing, and non-use values that accrue to the area while ensuring a minimum viable wolf population meant to prevent extinction. We show that the cost of wolf conservation paid by residents and visitors to the area falls substantially after delisting. These costs savings arise by taking advantage of differences in habitats and economies across the region resulting in an unequal spatial distribution of wolves and of wolf hunting opportunities. The cost savings from delisting are reduced when a more even distribution of wolves and hunting opportunity is achieved, highlighting a bioeconomic equity-efficiency tradeoff. Finally, we show that current livestock compensation programs cannot decrease the discrepancy between state and federal management following delisting but propose a federally-funded alternative that can. [ABSTRACT FROM AUTHOR]