Using ICESAT\u27s geoscience laser altimeter system to assess large scale forest disturbance caused by Hurricane Katrina

We assessed the use of GLAS data as a tool to quantify large-scale forest damage. GLAS data for the year prior to and following Hurricane Katrina were compared to wind speed, forest cover, and MODIS NPV maps to analyze senor sampling, and changes in mean canopy height. We detected significant losses in mean canopy height post-Katrina that increased with wind intensity, from ∼.5m in forests hit by tropical storm winds to ∼4m in forests experiencing category two force winds. Season of data acquisition was shown to influence calculations of mean canopy height. There was insufficient sampling to adequately detect changes at one degree resolution and less. We observed a strong relationship between delta NPV and post storm mean canopy heights. Changes in structure were converted into loss of standing carbon estimates using a height structured ecosystem model, yielding above ground carbon storage losses of ∼30Tg over the domain

Disturbance distance: quantifying forests' vulnerability to disturbance under current and future conditions

Disturbances, both natural and anthropogenic, are critical determinants of forest structure, function, and distribution. The vulnerability of forests to potential changes in disturbance rates remains largely unknown. Here, we developed a framework for quantifying and mapping the vulnerability of forests to changes in disturbance rates. By comparing recent estimates of observed forest disturbance rates over a sample of contiguous US forests to modeled rates of disturbance resulting in forest loss, a novel index of vulnerability, Disturbance Distance, was produced. Sample results indicate that 20% of current US forestland could be lost if disturbance rates were to double, with southwestern forests showing highest vulnerability. Under a future climate scenario, the majority of US forests showed capabilities of withstanding higher rates of disturbance then under the current climate scenario, which may buffer some impacts of intensified forest disturbanceinfo:eu-repo/semantics/publishedVersio

Proceedings of the Thirteenth International Society of Sports Nutrition (ISSN) Conference and Expo

Meeting Abstracts: Proceedings of the Thirteenth International Society of Sports Nutrition (ISSN) Conference and Expo Clearwater Beach, FL, USA. 9-11 June 201

Assessing the use of Geoscience Laser Altimeter System data to quantify forest structure change resultant from large-scale forest disturbance events- Case Study Hurricane Katrina Details

The biodiversity, structure, and functioning of forest systems in most areas are strongly influenced by disturbances. Forest structure can both influence and help indicate forest functions such as the storage and transfer of carbon between the land surface and the atmosphere. A 2007 report published by the National Research Council states that ‘Quantifying changes in the size of the [vegetation biomass] pool, its horizontal distribution, and its vertical structure resulting from natural and human-induced perturbations, such as deforestation and fire, and the recovery processes is critical for measuring ecosystem change.’ This study assessed the use of the Geoscience Laser Altimeter System (GLAS) to detect and quantify changes in forest structure caused by Hurricane Katrina. Data from GLAS campaigns for the year proceeding and following Katrina were compared to wind speed, forest cover, and damage maps to analyze sensor sampling, and forest structure change over a range of spatial scales. Results showed a significant decrease in mean canopy height of 4.0 m in forested areas experiencing category two winds, a 2.2 meter decrease in forests experiencing category one winds, and a 0.6 meter change in forests hit by tropical storm winds. Changes in structure were converted into carbon estimates using the Ecosystem Demography (ED) model to yield above ground carbon storage losses of ~30Tg over the domain. Although the greatest height loss was observed in areas hit by category two winds, these areas only contributed to a fraction (~3Tg) of the estimated above ground carbon storage losses resultant from Katrina, highlighting that small disturbance spread over a large area can account for as much as or more damage than intense disturbance over smaller areas. This finding stresses the importance of detecting and measuring the full extent of storm damage. While results highlighted the potential use of space-born Lidar in damage detection and quantification, they also emphasize limitations on the scope and scale at which current data can quantify hurricane related changes. Season of data acquisition was shown to influence calculations of mean canopy height and change. Limited sampling hindered our ability to make reliable estimates of height change and standing biomass loss at one degree resolution and smaller across the domain. These results have implications for sampling requirements in upcoming missions, such as DESDnyI, that will improve our ability to detect and quantify forest structure changes from disturbance events

Using ICESat’s Geoscience Laser Altimeter System (GLAS) to assess large-scale forest disturbance caused by Hurricane Katrina

n 2005, hurricane Katrina resulted in a large disturbance to U.S. forests. Recent estimates of damage from hurricane Katrina have relied primarily on optical remote sensing and field data. This paper is the first large-scale study to use satellite-based lidar data to quantify changes in forest structure from that event. GLAS data for the years prior to and following hurricane Katrina were compared to wind speed, forest cover, and damage data to assess the adequacy of sensor sampling, and to estimate changes in Mean Canopy Height (MCH) over all areas that experienced tropical force winds and greater. Statistically significant decreases in MCH post-Katrina were found to increase with wind intensity: Tropical Storm ∆MCH = − 0.5 m, Category 1 ∆MCH = − 2 m, and Category 2 ∆MCH = − 4 m. A strong relationship was also found between changes in non-photosynthetic vegetation (∆NPV), a metric previously shown to be related to storm damage, and post-storm MCH. The season of data acquisition was shown to influence calculations of MCH and MCH loss, but did not preclude the detection of major large-scale patterns of damage. Results from this study show promise for using space-borne lidar for large-scale assessments of forest disturbance, and highlight the need for future data on vegetation structure from space

Potential Vegetation and Carbon Redistribution in Northern North America from Climate Change

There are strong relationships between climate and ecosystems. With the prospect of anthropogenic forcing accelerating climate change, there is a need to understand how terrestrial vegetation responds to this change as it influences the carbon balance. Previous studies have primarily addressed this question using empirically based models relating the observed pattern of vegetation and climate, together with scenarios of potential future climate change, to predict how vegetation may redistribute. Unlike previous studies, here we use an advanced mechanistic, individually based, ecosystem model to predict the terrestrial vegetation response from future climate change. The use of such a model opens up opportunities to test with remote sensing data, and the possibility of simulating the transient response to climate change over large domains. The model was first run with a current climatology at half-degree resolution and compared to remote sensing data on dominant plant functional types for northern North America for validation. Future climate data were then used as inputs to predict the equilibrium response of vegetation in terms of dominant plant functional type and carbon redistribution. At the domain scale, total forest cover changed by ~2% and total carbon storage increased by ~8% in response to climate change. These domain level changes were the result of much larger gross changes within the domain. Evergreen forest cover decreased 48% and deciduous forest cover increased 77%. The dominant plant functional type changed on 58% of the sites, while total carbon in deciduous vegetation increased 107% and evergreen vegetation decreased 31%. The percent of terrestrial carbon from deciduous and evergreen plant functional types changed from 27%/73% under current climate conditions, to 54%/46% under future climate conditions. These large predicted changes in vegetation and carbon in response to future climate change are comparable to previous empirically based estimates, and motivate the need for future development with this mechanistic model to estimate the transient response to future climate changes

Modeling the Impacts of Disturbances on Carbon Dynamics Over Large Regions

The carbon balance of forest ecosystems is fundamentally linked to patterns of disturbance and recovery. Major disturbances entail either a rapid release of biomass carbon to the atmosphere (e.g. combustion), or a large transfer of biomass from live vegetation to dead material that either decomposes over a period of years (e.g. woody debris), or removed from the forest (e.g. wood products). Abrupt forest disturbances (e.g. fire, windstorms, land use) that generate gaps \u3e0.001 km2 have been shown to impact roughly 0.4-0.7 million km2 y-1 globally. At the same time, due to the relatively slow timescale of recovery, much of the landscape is in some stage of recovery from prior disturbances, gaining carbon. The impact of stochastic disturbances on forest ecosystems, integrated over large areas and relatively long times scales (decades), is generally thought to be small, based on the equilibrium land-atmosphere carbon balance. However, forest disturbance rates may not be stationary, i.e., may not fluctuate within a constant range of variability, due to climate change, population growth and changing land-use and resource demands, and this has consequences for forest and atmospheric carbon balance, climate feedbacks, and policies aiming to achieve particular atmospheric CO2 concentration targets. Here we briefly review progress and challenges for incorporating disturbances in models, present findings from large-scale simulations of forest disturbance from hurricanes and fires, and identify emerging strategies and data needs for projecting the impacts of disturbances on carbon dynamics over large regions

Tales of diversity: Genomic and morphological characteristics of forty-six <i>Arthrobacter</i> phages

<div><p>The vast bacteriophage population harbors an immense reservoir of genetic information. Almost 2000 phage genomes have been sequenced from phages infecting hosts in the phylum Actinobacteria, and analysis of these genomes reveals substantial diversity, pervasive mosaicism, and novel mechanisms for phage replication and lysogeny. Here, we describe the isolation and genomic characterization of 46 phages from environmental samples at various geographic locations in the U.S. infecting a single <i>Arthrobacter</i> sp. strain. These phages include representatives of all three virion morphologies, and Jasmine is the first sequenced podovirus of an actinobacterial host. The phages also span considerable sequence diversity, and can be grouped into 10 clusters according to their nucleotide diversity, and two singletons each with no close relatives. However, the clusters/singletons appear to be genomically well separated from each other, and relatively few genes are shared between clusters. Genome size varies from among the smallest of siphoviral phages (15,319 bp) to over 70 kbp, and G+C contents range from 45–68%, compared to 63.4% for the host genome. Although temperate phages are common among other actinobacterial hosts, these <i>Arthrobacter</i> phages are primarily lytic, and only the singleton Galaxy is likely temperate.</p></div

Genome organization of <i>Arthrobacter</i> phage Laroye, Cluster AL.

<p>See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0180517#pone.0180517.g005" target="_blank">Fig 5</a> for details.</p

Genome organization of <i>Arthrobacter</i> phage Gordon, Cluster AU.

<p>See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0180517#pone.0180517.g005" target="_blank">Fig 5</a> for details.</p