Slash fire hazard analysis on the Siskiyou National Forest

Potential increase in fire hazard as a result of timber harvesting is a concern of forest managers throughout the United States. Treating fuels can help reduce unacceptable fire hazards. To evaluate alternative fuel treatments, managers need to know their effects on fire hazard. A decision analysis approach to estimating fire hazard in terms of expected burned area was applied to a watershed in the Siskiyou National Forest (Oregon). Three treatment alternatives (do nothing and two levels of yarding unmerchantable material) were evaluated, and the effects of the treatments were projected over a 90-yr period. Initially, the effects of applying a treatment are small. After 50 years of treatment, the most intense alternative can be expected to show almost a 50% reduction in burned area compared to no treatment. The procedure also estimates burned are by fire size and fire intensity classes. Managers may find this useful for estimating expected fire effects associated with a particular fuel treatment regime.     

Modeling the long-term effects of fuelwood harvests on Pinyon-Juniper Woodlands

In the Southwestern United States, increasing demand for firewood has quickly promoted pinyon-juniper woodlands to commercial status. Slow recovery rates for pinyon and juniper and inadequate mensuration data present significant obstacles to predictive management efforts. Many National Forest districts have witnessed continued fuel use for at least the past 100 years. To explore the need for long-term analysis at the district level, we have developed FORMAN I, a computer simulation written in FORTRAN IV that models prolonged fuel harvesting and its impact on pinyon-juniper woodlands. The technique is well-suited for historical analyses and we comply with an initial application that involves the suggested impact of prehistoric peoples on a marginal woodland in Chaco Canyon, New Mexico. To accentuate the significance of the simulation, we have deliberately overestimated woodland parameters while maintaining conservative annual rates for firewood procurement. A low-density woodland (less than 14.8 cords/ha) is completely depleted within 200 years when subjected to tenth-through-twelfth century estimates of human demography for the canyon. Interesting conclusions are drawn from the lack of pinyon-juniper recovery at Chaco over the past millennium. Traditional assumptions, such as the pristine state of Southwestern vegetation prior to historic settlement and subsequent invasion of marginal grasslands by pinyon and juniper, are questioned.     

EFFECTS OF URBANIZATION ON BASE FLOW OF SELECTED SOUTH-SHORE STREAMS,LONG ISLAND,NEW YORK1

ABSTRACT: Hydrograph analysis of six streams on the south shore of Long Island indicates that eastward urbanization during the last three decades has significantly reduced base flow to streams. Before urbanization, roughly 95 percent of total annual stream flow on Long Island was base flow. In urbanized southwestern Nassau County, storm water sewerage, increased impervious surface area, and sanitary sewerage have reduced base flow to 20 percent of total stream flow. In an adjacent urbanized but unsewered area in southeastern Nassau County, base flow has decreased to 84 percent of total annual stream flow. In contrast, base flow in two streams in rural areas has remained virtually constant, averaging roughly 95 percent of total annual flow throughout the 1955-70 study period. Double-mass curve analysis of base flow as a percentage of total annual stream flow indicates that (1) changes in stream flow characteristics began in the early 1960's in the sewered area and in the late 1960's in the later urbanized, unsewered area, and (2) a new equilibrium has been established between the streams in the sewered area and the new hydrologic characteristics of their urbanized drainage basins.     

Fitting a Gamma Distribution Over a Synthetic Unit Hydrograph1

ABSTRACT: Several methods for synthetic unit hydrographs are available in the literature. Most of these methods involve the hand fitting of a curve over a set of a few hydrograph points, which can sometimes be a subjective task. Besides, the user often finds it difficult or simply neglects to adjust the generated unit graph to a runoff volume of one unit (inch, cm, or mm). It is the purpose of this paper to present to the design hydrologist a simple method to fit a smooth gamma distribution over a single point specified by the unit hydrograph peak and the time to peak with a guaranteed unit depth of runoff.     

Reviews

Planning theory

Andreas Faludi

Pergamon Press, Oxford, 1973. Hard cover £4.75, flexi‐cover £3.

PLANNING AND THE INNOVATION PROCESS (Progress in Planning, Vol. 1, Part 3)

Ray Jefferson

Pergamon Press, Oxford, 1973

THRESHOLD ANALYSIS MANUAL

Scottish Development Department H.M.S.O., London, 1973. £6

THE PLANNER IN SOCIETY: THE CHANGING ROLE OF A PROFESSION

David Eversley

Faber and Faber, London, 1973. £4.75.

SUB‐REGIONAL PLANNING STUDIES: AN EVALUATION

T. M. Cowling and G. C. Steeley

Pergamon Press, Oxford, 1973. £3.80

SKETCHBOOKS OF PAOLO SOLERI

Paolo Soleri.

M.I.T. Press, Cambridge, Massachusetts & London, England, 1971.

ARCOLOGY: THE CITY IN THE IMAGE OF MAN.

Paolo Soleri.

M.I.T. Press, Cambridge, Massachusetts & London, England, 1969.

FREDERICK LAW OLMSTED AND THE AMERICAN ENVIRONMENTAL TRADITION

Albert Fein

George Braziller, New York. $10.00 cloth. $3.95 paper.

ECOLOGY AND RECLAMATION OF DEVASTED LAND (2 vols.) ed. Russel Hutnick and Grant Davis

Gordon and Breach, New York, 1973. £25.00.

MAN MADE THE LAND: Essays in English Historical Geography

Ed. Alan R. H. Baker and J. B. Harley.

David and Charles, Newton Abbot, 1973. £5.25.

THE UNKNOWN URBAN REALM (Vol. 2, Europe 2,000, Project 3, Urbanization, Planning Human Environment in Europe)

U. Neveling, R. Sulzer, W. Ubbens, G. Wersig.

Martinus Nijhoff, The Hague, 1973.     

EXPERIMENTAL DREDGING TO CONVERT LAKE BOTTOM FROM ABIOTIC MUCK TO PRODUCTIVE SAND1

ABSTRACT: Conversion of muck to sand bottom was tested to increase benthic production in two eutrophic Florida lakes, and preliminary results indicate that benthos will be increased in areas converted to sand. Muck removal with a specially designed dredge, or “Mudcat,” was tested in Trout Lake. The Mudcat removed 41,650 cu. yds. of muck and exposed 17 acres of sand bottom, but 10 of those acres developed thin layers of muck, which proved too soft to be picked up by the Mudcat. Consequently, only 7 acres were satisfactorily converted. Bottom redistribution with a suction-type dredge was tested in Lake Carlton, and 14 acres were converted from muck to sand. Sand covered with muck was pumped from midlake areas to more peripheral areas of the lake where water depths were 11 to 13 feet and muck layer about 1.5 feet deep. The bottom was built up to an elevation above the previous muck elevation. Several methods for depositing the sand were tested. Level areas of sand fill developed accumulations of muck from fallout following dredging activity. Piles or dunes provided the best cost-return ratio. The bottom in filled areas changed very little during a 1½ year period following filling.     

CONTRASTS IN COMMUNITY ACTION AND OPINION1

ABSTRACT. Opinion or attitude surveys and observations of people's actions are complementary research tools, but they often provide different results. This was the case where two communities, one rural, one suburban, made waste water management decisions which would promote population growth while survey data indicated that community attitudes were neutral or slightly opposed to population growth. Observation of action, and expanding the range of survey response variation revealed that the structure of both community opinion and action was primarily influenced by small groups of people with very strong feelings favoring and disfavoring population growth. Those with very strong feelings were the ones observed to be acting to promote or retard growth.     

THE FATE OF NITRATE IN LAKE SEDIMENT COLUMNS1

ABSTRACT: To investigate the magnitude of denitrification and assimilatory nitrate reduction as these reactions relate to the fate of nitrate reaching sediments via groundwater seepage, undisturbed core samples of sediments (40 cm length) from two lakes (Mendota and Tomahawk) were leached from the bottom (at 1.4 cm/day) with a solution of ¹⁵N-nitrate (10 mg N/liter). The sediment columns were fitted with Pt electrodes to measure the oxidation-reduction (Eh) potential. While leaching removed considerable ammonium-N and soluble organic N, essentially no ¹⁵N had passed through the columns by 50 days. The Eh readings indicated that denitrification was occurring in the lower portions of the columns. The ¹⁵N distribution of the sediment N after 50 days showed that about 15 to 26% of the added nitrate-N was converted to organic N and ammonium-N. The data show that denitrification can be a significant N sink in seepage lakes.