Acoustic propagation through a forest edge can produce complicated pressure time histories because of scattering from the trees and changes in the microclimate and ground parameters of the two regions. To better understand these effects, a field experiment was conducted to measure low-frequency acoustic pulses propagating in an open field, a forest, and passing through a forest edge in both directions. Waveforms measured in the open field were simple impulses with very low scattering, whereas waveforms at the edge and within the forest had stronger reverberations after the direct arrival. The direct wave pulse shapes increased in duration in accordance with the path length in the forest, which had an effective flow resistivity 12 to 13 that of the grassy open field. The measurements exhibit different rates of attenuation in the two regions, with relatively lower attenuation in the open field than higher rates in the forest. Decay of SEL transmitted into the forest was 4 dB more per tenfold distance than for outbound transmission. Stronger attenuation in the 1-2 kHz range occurs when propagating into the forest. While the measured meteorological profiles revealed three distinct microclimates, meteorological effects are not sufficient to explain the apparent non-reciprocal propagation.
Abstract:A 2007 Report to Congress documented a crucial factor in the loss of Army training land: uncontrolled vegetation growth. Of the 53 installations surveyed for the report, 30 reported that approximately 12 percent of their training lands were unusable for certain types of training. Uncontrolled vegetation was a source of such problems as an inability to conduct mounted and dismounted maneuver training, interference with equipment used in line-of-sight training, safety issues, and damage to equipment and structures. Of the 11 plant species (or groups) identified by installations as "uncontrolled vegetation," six were invasive plants, of which the two invasive plants most commonly identified were Kudzu (Pueraria montana) and Multiflora Rose (Rosa multiflora). This work provides a snap-shot of current research and scientific knowledge related to the invasive plant species Multiflora Rose, its impact on the Army, and a concise representation of control technologies for military land managers.
Background:Military and nonmilitary organizations need the capability to support their expeditionary forces by selecting a temporary base of operations that projects a minimal footprint and reduces logistical burdens. For example, strategically sited temporary bases anticipate impacts on the local context and its population of siting and operating temporary bases.
Objective:This paper describes a methodology to assess the practicality of incorporating local construction materials when planning for contingency operations in a given region. While the assessment methodology was originally developed for military planners, the principles and methods are applicable to any organization that is considering building and operating temporary locations in foreign nations.
Method:The methodology assesses factors such as population densities, main building types, geographical regions, port locations, railroad locations, road networks, airport locations, flood-risk areas, and construction materials. The methodology optimizes all factors to yield the best material-based solution for site selection. To demonstrate the developed methodology, two hypothetical case studies are described-Dhaka in Bangladesh for its high-population density and Maiduguri in Nigeria for its low-population density and potential for disruption.
Results:This methodology provides a contingency site selection process that does not currently exist and will assist in the reduction of materiel demand, minimize footprint, and reduce the risk to personnel. The methodology captures factors such as population densities, main building types, geographical regions, port locations, railroad locations, road networks, airport locations, flood-risk areas, and construction materials and optimizes all factors to yield the best material-based solution for site selection.
Conclusion:This methodology provides a contingency site selection process that does not currently exist for mission planners. It is designed to produce a methodology with a goal of developing a GIS-based decision support tool to assist in siting bases of operations.
Five-year diameter growth, basal area growth, and mortality for five upland hardwood species in northern Lower Michigan were compared to projections from Lake States TWIGS. The species studied were northern red oak, white oak, other red oak (pin oak and black oak combined), sugar maple, and red maple. The validation data consisted of individual tree measurements from 44 stands across 10 ecological land types on the Manistee National Forest. The stands were measured in 1986 and 1991; during this time interval stands experienced a drought and outbreaks of leaf defoliators. For individual dbh classes, 5 yr diameter growth was predicted within ± 0.3 in. for all species. Mean errors for BA projections were within ± 5 ft²/ac for all species, and mean error for trees/ac ranged from - 33 for other red oak to + 16 for sugar maple. Although precision was variable, Lake States TWIGS provided accurate predictions of 5 yr diameter growth for the five species tested. Projections of mortality were less accurate. North. J. Appl. For. 13(4):00-00.
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