Developing and Using Fire Scar Histories in the Southern and Eastern United States

Land managers developing fire management plans in the eastern and southern United States lack quantitative information on historic fire regimes. Twelve new fire histories were developed from dated fire scars on trees from regions where no fire scar history data had existed before in the states of Alabama, Louisiana, Kentucky, Iowa, Wisconsin, and Michigan. Sites represent highly variable climates from extreme cold (with long snow cover duration) to subtropical. All sites utilized oak or pine recorder species that were collected from closed forest to open savanna structures. Pre-industrial mean fire intervals ranged from 3 to more than 35 years at sites that typically encompassed less than 2 km2 in area. The most frequent fire regime was found in Louisiana‟s Kisatchie National Forest (MFI = 3 yrs) while the longest fire intervals were at inland sites near the shore of Lake Superior (MFI \u3e 35 yrs) some 1900 kilometers to the north. The subtropical site in Louisiana is perhaps the only site in the U.S. where fires are documented to have occurred more than once a year. The history of fire at sites in Wisconsin, Louisiana, and Michigan showed distinct temporal progressions in changes in fire frequency that we attributed to changing human population. Sites in Wisconsin showed potential for very large fires associated with drought years. Fire history data analyses and summaries were presented at multiple venues (workshops, conferences) and have been published in scientific journals and reports to regional land managers. Fire history data has also been made publicly available through the International Multiproxy Paleofire Databank (IMPD). New fire history data from this project combined with previously collected fire history data from the Missouri Tree-Ring Laboratory and published fire histories in North America were used to parameterize and calibrate a continental fire frequency model based on climate. The most important contribution of this model is towards understanding climate forcing of fire regimes across the continental U.S. We have developed a suite of climate-based fire frequency models for the continental U.S. that show to be highly robust. Models and calibrations were validated with empirical fire history data during pre-industrial periods so to minimize non-climate influences associated with U.S. settlement (land conversion, changing cultures). Fire frequency models follow theoretical concepts from physical chemistry, utilize spatially-explicit fire and climate data, and were parameterized and validated using statistical methods. Data from fire history studies were accumulated from 37 states and include data based on fire scars (n = 168), expert estimates (n = 7) and charcoal (n = 3). Historic mean fire interval (MFI) models were parameterized using mean maximum temperature, precipitation, their interaction, and estimated population density (anthropogenic ignitions). Models are being used to: assess the role of climate in forcing fire frequency, map coarse-scale historic fire frequency for the continental U.S., and assess departures in fire regimes and smoke emissions

Developing and Using Fire Scar Histories in the Southern and Eastern United States

Land managers developing fire management plans in the eastern and southern United States lack quantitative information on historic fire regimes. Twelve new fire histories were developed from dated fire scars on trees from regions where no fire scar history data had existed before in the states of Alabama, Louisiana, Kentucky, Iowa, Wisconsin, and Michigan. Sites represent highly variable climates from extreme cold (with long snow cover duration) to subtropical. All sites utilized oak or pine recorder species that were collected from closed forest to open savanna structures. Pre-industrial mean fire intervals ranged from 3 to more than 35 years at sites that typically encompassed less than 2 km2 in area. The most frequent fire regime was found in Louisiana‟s Kisatchie National Forest (MFI = 3 yrs) while the longest fire intervals were at inland sites near the shore of Lake Superior (MFI \u3e 35 yrs) some 1900 kilometers to the north. The subtropical site in Louisiana is perhaps the only site in the U.S. where fires are documented to have occurred more than once a year. The history of fire at sites in Wisconsin, Louisiana, and Michigan showed distinct temporal progressions in changes in fire frequency that we attributed to changing human population. Sites in Wisconsin showed potential for very large fires associated with drought years. Fire history data analyses and summaries were presented at multiple venues (workshops, conferences) and have been published in scientific journals and reports to regional land managers. Fire history data has also been made publicly available through the International Multiproxy Paleofire Databank (IMPD). New fire history data from this project combined with previously collected fire history data from the Missouri Tree-Ring Laboratory and published fire histories in North America were used to parameterize and calibrate a continental fire frequency model based on climate. The most important contribution of this model is towards understanding climate forcing of fire regimes across the continental U.S. We have developed a suite of climate-based fire frequency models for the continental U.S. that show to be highly robust. Models and calibrations were validated with empirical fire history data during pre-industrial periods so to minimize non-climate influences associated with U.S. settlement (land conversion, changing cultures). Fire frequency models follow theoretical concepts from physical chemistry, utilize spatially-explicit fire and climate data, and were parameterized and validated using statistical methods. Data from fire history studies were accumulated from 37 states and include data based on fire scars (n = 168), expert estimates (n = 7) and charcoal (n = 3). Historic mean fire interval (MFI) models were parameterized using mean maximum temperature, precipitation, their interaction, and estimated population density (anthropogenic ignitions). Models are being used to: assess the role of climate in forcing fire frequency, map coarse-scale historic fire frequency for the continental U.S., and assess departures in fire regimes and smoke emissions

The Fire-Oak Literature of Eastern North America: Synthesis and Guidelines

Guidelines for using prescribed fire to regenerate and restore upland oak forests, woodlands, and savannas in eastern North America were developed by synthesizing the results of more than 100 scientific publications. The first four chapters provide background information on the values of oak ecosystems, eastern fire history, oak’s adaptations to fire, and the findings of fire-oak research conducted over the past 50 years. The final chapter synthesizes that background information into guidelines that explain how to use prescribed fire to facilitate oak seedling establishment, release oak reproduction from competing mesophytic hardwoods, and rehabilitate open oak woodlands, oak savannas, and scrub oak communities. A reference section is also provided for readers desiring to delve more deeply into the associations between periodic fire and oak forests, woodlands, and savannas

An X-ray Selected Galaxy Cluster at z=1.26

We report the discovery of an X-ray luminous galaxy cluster at z=1.26. RXJ0848.9+4452 was selected as an X-ray cluster candidate in the ROSAT Deep Cluster Survey, on the basis of its spatial extent. Deep optical and near-IR imaging have revealed a galaxy overdensity around the peak of the X-ray emission, with a significant excess of red objects with J-K colors typical of elliptical galaxies at z>1. Spectroscopic observations at the Keck II telescope have secured 6 galaxy redshifts in the range 1.257=1.261), within a 35 arcsec radius around the peak X-ray emission. This system lies only 4.2 arcmin away (5.0 h^{-1}_{50} comoving Mpc, q_0=0.5) from the galaxy cluster ClG J0848+4453, which was identified by Stanford et al. (1997) at z=1.273 in a near-IR field galaxy survey, and is also known to be X-ray luminous. Assuming that the X-ray emission is entirely due to hot intra-cluster gas, both these systems have similar rest frame luminosities L_x ~=1x10^{44} ergs/s (0.5-2.0 keV band). In combination with our spectrophotometric data for the entire 30 arcmin^2 field, this suggests the presence of a superstructure, consisting of two collapsed, possibly virialized clusters, the first detected to date at z>1.Comment: To appear in The Astronomical Journal, 24 pages, 8 figures, 1 color jpg plate (fig.7), see http://www.eso.org/~prosati/lynx/plate_fig7.jp

The Clustering of Extremely Red Objects

We measure the clustering of Extremely Red Objects (EROs) in ~8 deg^2 of the NOAO Deep Wide Field Survey Bo\"otes field in order to establish robust links between ERO z~1.2 and local galaxy z<0.1 populations. Three different color selection criteria from the literature are analyzed to assess the consequences of using different criteria for selecting EROs. Specifically, our samples are (R-K_s)>5.0 (28,724 galaxies), (I-K_s)>4.0 (22,451 galaxies) and (I-[3.6])>5.0 (64,370 galaxies). Magnitude-limited samples show the correlation length (r_0) to increase for more luminous EROs, implying a correlation with stellar mass. We can separate star-forming and passive ERO populations using the (K_s-[24]) and ([3.6]-[24]) colors to K_s=18.4 and [3.6]=17.5, respectively. Star-forming and passive EROs in magnitude limited samples have different clustering properties and host dark halo masses, and cannot be simply understood as a single population. Based on the clustering, we find that bright passive EROs are the likely progenitors of >4L^* elliptical galaxies. Bright EROs with ongoing star formation were found to occupy denser environments than star-forming galaxies in the local Universe, making these the likely progenitors of >L^* local ellipticals. This suggests that the progenitors of massive >4L^* local ellipticals had stopped forming stars by z>1.2, but that the progenitors of less massive ellipticals (down to L^*) can still show significant star formation at this epoch.Comment: 19 pages, 16 figures, 4 tables, Accepted to ApJ 27th November 201

The Chandra XBootes Survey - III: Optical and Near-IR Counterparts

The XBootes Survey is a 5-ks Chandra survey of the Bootes Field of the NOAO Deep Wide-Field Survey (NDWFS). This survey is unique in that it is the largest (9.3 deg^2), contiguous region imaged in X-ray with complementary deep optical and near-IR observations. We present a catalog of the optical counterparts to the 3,213 X-ray point sources detected in the XBootes survey. Using a Bayesian identification scheme, we successfully identified optical counterparts for 98% of the X-ray point sources. The optical colors suggest that the optically detected galaxies are a combination of z<1 massive early-type galaxies and bluer star-forming galaxies whose optical AGN emission is faint or obscured, whereas the majority of the optically detected point sources are likely quasars over a large redshift range. Our large area, X-ray bright, optically deep survey enables us to select a large sub-sample of sources (773) with high X-ray to optical flux ratios (f_x/f_o>10). These objects are likely high redshift and/or dust obscured AGN. These sources have generally harder X-ray spectra than sources with 0.1<f_x/f_o<10. Of the 73 X-ray sources with no optical counterpart in the NDWFS catalog, 47 are truly optically blank down to R~25.5 (the average 50% completeness limit of the NDWFS R-band catalogs). These sources are also likely to be high redshift and/or dust obscured AGN.Comment: 19 pages, 13 figures, ApJ accepted. Catalog can be found at: http://www.noao.edu/noao/noaodeep or ftp://archive.noao.edu/pub/catalogs/xbootes

Avances en la restauración de bosques de roble en tierras bajas agrícolas del Río Mississippi y sus tributarios

The lowlands associated with the Mississippi River and its tributaries historically supported extensive broadleaf forests that were particularly rich in oak (Quercus spp.) species. Beginning in the 1700s, deforestation for agriculture substantially reduced the extent of the original forest, and fragmented the remainder into small parcels. More recently, declines in agricultural commodity prices, along with increased awareness of conservation have provided opportunities to restore a substantial base of agriculture land to broadleaf forests. While afforestation of former agricultural land began over 40 years ago in the region, organized, large-scale afforestation efforts have peaked over the last 15 years with increased interest in forest sustainability, biodiversity conservation, carbon sequestration, and water quality. Large-scale implementation of afforestation to restore broadleaf forest cover has raised many issues particular to oak species biology and ecology that impact the restoration process. The purpose of this manuscript is to present knowledge gained from research and experience with oak forest afforestation in the eastern United States as a model for developing approaches to initiate oak forest restoration in other regions. To accomplish this, we outline issues associated with the oak regeneration strategy and natural stand development patterns that have hampered large-scale restoration of oak-dominated forests. Furthermore, we present effective afforestation approaches used to reduce the impact of these challenges, and frame these approaches under the context of oak forest afforestation that addresses multiple management objectives and provides for value and function on a sustainable basis.Las zonas bajas asociadas al río Mississippi y sus tributarios albergaron históricamente extensos bosques de latifoliadas particularmente ricos en especies de roble (Quercus spp.). A comienzos del siglo xviii, la deforestación causada por la agricultura sostenible redujo la extensión del bosque original y fragmentó el restante en pequeñas parcelas. Más recientemente, la reducción en los precios de los productos, junto con la creciente conciencia por la conservación, han brindado oportunidades para restaurar una porción considerable de tierras agrícolas en bosques de latifoliadas. Mientras que las primeras reforestaciones de tierras agrícolas comenzaron hace 40 años en la región, los esfuerzos para realizar reforestaciones organizadas y a gran escala han tenido su máximo en los últimos 15 años, debido al creciente interés en la sostenibilidad de los bosques, la conservación de la biodiversidad, el secuestro de carbono y la calidad de las aguas. Implementar la reforestación a gran escala para restaurar bosques de latifoliadas involucra muchos aspectos de la biología y ecología de las especies de roble que impactan el proceso de restauración. El propósito de este artículo es mostrar los conocimientos que se han obtenido a través de investigaciones y experiencias en la reforestación de bosques de roble en el oriente de los Estados Unidos, como modelo para desarrollar avances que permitan iniciar la restauración de los bosques de roble en otras regiones. Para lograr esto delineamos aspectos asociados con las estrategias de regeneración de los robles y los patrones de desarrollo natural de los rodales que han limitado la reforestación a gran escala en bosque dominados por roble. Más aún, presentamos avances efectivos en reforestación usados para reducir el impacto de estos cambios, y enmarcamos estos avances en el contexto de la reforestación de bosques de roble que responde a múltiples objetivos de manejo y brinda valor y función sobre una base sostenible

Assessing Restoration Potential of Fragmented and Degraded Fagaceae Forests in Meghalaya, North-East India

The montane subtropical broad-leaved humid forests of Meghalaya (Northeast India) are highly diverse and situated at the transition zone between the Eastern Himalayas and Indo-Burma biodiversity hotspots. In this study, we have used inventory data from seedlings to canopy level to assess the impact of both biotic and abiotic disturbances on structure, composition, and regeneration potential of the Fagaceae trees of these forests. Fagaceae trees are considered as the keystone species in these forests due to their regional dominance and their importance as a fuel wood source, and also because they form an important component of climax community in these forests. Unfortunately, these forests are highly degraded and fragmented due to anthropogenic disturbances. We have assessed, for the first time, the restoration potential (i.e., capacity to naturally regenerate and sustain desired forest structure) of Fagaceae species in the genera Lithocarpus Blume, Castanopsis (D. Don) Spach, and Quercus Linn. We also evaluated how biotic and abiotic factors, as well as anthropogenic disturbances, influence the restoration potential of these species in six fragmented forest patches located along an elevational gradient on south-facing slopes in the Khasi Hills, Meghalaya. Fagaceae was the most dominant family at all sites except one site (Laitkynsew), where it was co-dominant with Lauraceae. Fagaceae forests have shown high diversity and community assemblages. Fagaceae species had high levels of natural regeneration (i.e., seedlings and saplings) but low recruitment to large trees (diameter at breast height or DBH ≥ 10 cm) at all sites. The ability to sprout was higher in Fagaceae tree species than non-Fagaceae tree species. We have shown that human disturbance and structural diversity were positively related to regeneration of Fagaceae tree species due to high sprouting. However, with increasing human disturbance, recruitment of saplings and pole-sized trees to mature trees hampered the resulting proportion of mature Fagaceae tree species. This study provides a means for assessing regeneration and a basis for forest management strategies in degraded and fragmented forests of Meghalaya

Chandra Detection of a TypeII Quasar at z=3.288

We report on observations of a TypeII quasar at redshift z=3.288, identified as a hard X-ray source in a 185 ks observation with the Chandra X-ray Observatory and as a high-redshift photometric candidate from deep, multiband optical imaging. CXOJ084837.9+445352 (hereinafter CXO52) shows an unusually hard X-ray spectrum from which we infer an absorbing column density N(H) = (4.8+/-2.1)e23 / cm2 (90% confidence) and an implied unabsorbed 2-10 keV rest-frame luminosity of L(2-10) = 3.3e44 ergs/s, well within the quasar regime. Hubble Space Telescope imaging shows CXO52 to be elongated with slight morphological differences between the WFPC2 F814W and NICMOS F160W bands. Optical and near-infrared spectroscopy of CXO52 show high-ionization emission lines with velocity widths ~1000 km/s and flux ratios similar to a Seyfert2 galaxy or radio galaxy. The latter are the only class of high-redshift TypeII luminous AGN which have been extensively studied to date. Unlike radio galaxies, however, CXO52 is radio quiet, remaining undetected at radio wavelengths to fairly deep limits, f(4.8GHz) < 40 microJy. High-redshift TypeII quasars, expected from unification models of active galaxies and long-thought necessary to explain the X-ray background, are poorly constrained observationally with few such systems known. We discuss recent observations of similar TypeII quasars and detail search techniques for such systems: namely (1) X-ray selection, (2) radio selection, (3) multi-color imaging selection, and (4) narrow-band imaging selection. Such studies are likely to begin identifying luminous, high-redshift TypeII systems in large numbers. We discuss the prospects for these studies and their implications to our understanding of the X-ray background.Comment: 28 pages, 5 figures; to appear in The Astrophysical Journa