Ecological Relations in the Pitch Pine Plains of Southern New Jersey

An investigation was undertaken with the primary object of determining the factors responsible for the peculiar development of the vegetation in the Plains community. The conclusion ·is reached that the Plains areas are capable of supporting forest growth similar to that in the Pine Barrens. Inasmuch as the Plains owe their continued existence to repeated fires, it is obvious that effective fire protection is the first and most important step toward their rehabilitation

Trends and Silvicultural Significance of Upland Forest Successions in Southern New England

The problems encountered in the silvicultural treatment of southern New England forests are many. They result largely from the extremely diverse and complex conditions under which the forest is developed. Due to the glaciated nature of the region the soil character changes radically within relatively short distances. With changes in soil from place to place come minor changes of forest composition. One of the chief reasons for the problems which the silviculturalist encounters in this region is the large number of species which make up the stands. There are approximately thirty commercially important forest trees in southern New England. The complicated character of the stands makes a knowledge of their development indispensable to silvicultural practice. It is well known that forest vegetation is continually undergoing change; it is unstable. This means that it must be studied not as a static but as a dynamic entity; in other words, it must be considered from the point of view of its successional development

Aboriginal man and white man as historical causes of fires in the boreal forest, with particular reference to Alaska

The boreal forest of North America is especially liable to destruction by fires. It is a region in which forest fires have been extremely common and wide spreading. Lightning is certainly one of the causes of fires but man, both aboriginal and white, has been an even more prolific source. The general attitude of aboriginal man toward fire was that of carelessness. Campfires were in general use and the evidence is that they were not carefully extinguished but frequently started forest fires. Use of fire in signaling was widespread and must have been a major source of forest fires. Wherever the birch bark canoe was used, frequent gumming of sewn seams was necessary along with repairs of cracks or tears in the bark. This necessitated making a fire for heating and applying the gum; the evidence is that this use of fire at least occasionally lead to fires in the forest. Fires were at times used in hunting but this practice probably was not an important source of forest burning. On some occasions, at least, aboriginal man seems to have employed fire in warfare but evidence on this use is scanty. In his efforts to combat mosquitoes and gnats, aboriginal man generally employed fire and smoke and this led to frequent forest fires. Of the miscellaneous uses of fire by aboriginal man that occasionally must have led to forest burning the following seem most worthy oi mention: clearing away of forest growth, cutting down trees, cutting up of trunks of fallen, or felled trees and killing trees for a supply of dry fuel. It seems certain that even prior to contact with white man, aboriginal man was responsible for frequent and widespread fires in the boreal forest. White man was, without doubt, the cause of even more fires in the boreal forest than was aboriginal man. He was generally careless and possessed easier means of striking fire. Campfires left without being extinguished resulted in a tremendous amount of forest burning. The frequent practice of setting fires to provide a supply of dry fuelwood likewise led to much forest destruction. Fires set to combat the mosquito pest were so frequently a cause of forest burning that it was commonly said that "mosquitoes cause more fires than any other one thing." Use of fire in signaling was not confined to the natives; the practice was also employed by white man and is known to have resulted in extensive forest fires. White man also adopted, at least occasionally, the practice of using fire in hunting. He burned off the forest to promote the growth of grass for his livestock, and he employed fire in clearing land. Prospectors were known to burn the forest to remove the vegetation mantle and expose the surface rock. Incredible as it may be, white man is also known to have set the forest afire just to see it burn or "for fun." In the boreal forest there were many fires whose causes are unknown. Some of these must have resulted from lightning but it is likely that most of them were caused by man, either aboriginal or white. It is probable that there have been fires in the northern forests ever since there were forests to burn. Destruction of timber and other values has been enormous but the boreal forest has generally shown a remarkable capacity to recover, to rise again, phoenix-like, from its own ashes.Gerald W. Williams Collectio

The Physical Nature of Lyman Alpha Emitting Galaxies at z=3.1

We selected 40 candidate Lyman Alpha Emitting galaxies (LAEs) at z ~=3.1 with observed frame equivalent widths >150A and inferred emission line fluxes >2.5x10^-17 ergs/cm^2/s from deep narrow-band and broad-band MUSYC images of the Extended Chandra Deep Field South. Covering 992 sq. arcmin, this is the largest ``blank field'' surveyed for LAEs at z ~3, allowing an improved estimate of the space density of this population of 3+-1x10^-4 h_70^3/Mpc^3. Spectroscopic follow-up of 23 candidates yielded 18 redshifts, all at z ~=3.1. Over 80% of the LAEs are dimmer in continuum magnitude than the typical Lyman break galaxy spectroscopic limit of R= 25.5 (AB), with a median continuum magnitude R ~=27 and very blue continuum colors, (V-z) ~=0. Over 80% of the LAEs have the right UVR colors to be selected as Lyman break galaxies, but only 10% also have R<=25.5. Stacking the UBVRIzJK fluxes reveals that LAEs have stellar masses ~=5x10^8 h_70^-2 M_sun and minimal dust extinction, A_V < ~ 0.1. Inferred star formation rates are ~=6 h_70^-2 M_sun/yr, yielding a cosmic star formation rate density of 2x10^-3 h_70 M_sun/yr/Mpc^3. None of our LAE candidates show evidence for rest-frame emission line equivalent widths EW_rest>240A which might imply a non-standard IMF. One candidate is detected by Chandra, implying an AGN fraction of 2+-2% for LAE candidate samples. In summary, LAEs at z ~ 3 have rapid star formation, low stellar mass, little dust obscuration and no evidence for a substantial AGN component.Comment: ApJ Letters, in press, very minor revisions to match accepted version, 4 pages with 2 color figure

LSST Science Book, Version 2.0

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo