Succession following shifting cultivation was studied in secondary forests (5 to 40 years old) and a primary forest in Bragantina region, Para, Brazil. Secondary forests covered 62% of the study area (89 km² ) and crops and pasture 18%. Soil analyses showed an increase in pH, exchangeable calcium, magnesium and potassium and a decrease of organic matter and exchangeable aluminium, immediately after burning. Organic matter and extractable phosphorus increased with forest age, exchangeable aluminium and potassium were the same in both secondary and primary forests and exchangeable calcium and magnesium remained higher in the secondary forests. The highest densities of individuals and the least basal area and height were found in the younger secondary forests. The number of woody species (≥5 cm dbh) 250-m2 plot ranged from 8 to 17 in the secondary forests and 17 to 27 in the primary forest. Ordination and classification of floristic data suggested four successional communities. The forests regenerated readily and studies showed: the largest seed bank (0-5 cm) in the 5-years-old forest (1190 ± 284 seeds m-2) and a decrease with age to 137 ±19 seeds m-2 in the primary forest; the highest seed rain in the 5-years-old forest (883 ± 230 seeds m-2) and least in the primary forest (220 ± 80); 46% of the smaller plants (≥1 m tall, < 5 cm dbh) were seedlings and 54% were sprouts in the 5-years-old forest but in the 10-years and 20-years-old forests, seedlings (81%) predominated; adult plants (≥5 cm db h) in 5 to 20-years-old plots regenerated mainly from sprouts. Even after about 90 years of shifting cultivation the region has the potential for forest regeneration and the soil nutrients are able to recover to values similar to those in the primary forest. This raises the hope that, if a land use plan for Bragantina could be implemented, then it would be successful.

Generally it is not adequate to calculate an allowable cut for a property by only one formula or method. Usually it is preferable to utilize all the information available with as many suitable formulae or methods as possible to obtain reasonable estimates of the yearly utilization rates by several approaches. For the University Research Forest fifteen different formulae and methods were selected for comparison, because their basic assumptions appeared applicable to this forest. The methods and formulae tested were: Methods: Area regulation, Area-volume check, Area-volume allotment, Barnes’ and H. A. Meyer's. Formulae: Austrian, Black Hills, Grosenbaugh, Hanzlik, Hundeshagen, Kemp, W. H. Meyer, S. Petrini (compound and simple interest) and Von Mantel. Appropriate inventory techniques were developed in order to collect the necessary information regarding rates of growth, mortality and numbers of trees per acre by diameter classes. Present and future decadal growing stocks were estimated. Simple and compound growth rates, including and excluding ingrowth, for all types were calculated separately for stands over eighty years of age and for stands under eighty years. The inventory was based on the areas and estimates taken from 1961 aerial photographs supplemented by both temporary and permanent sample plots, employing primarily the principles of the point sampling techniques as described by L. R. Grosenbaugh. After substituting the actual data into the formulae and various methods, allowable cut estimates for 3.1, 9.1, 11.1, and 13.1 inches minimum diameter limits were calculated. Allowances were made for an intermediate standard of utilization and for waste, breakage and decay. Considering the inventory and the allowable cut calculations it was found that: 1. Simple area regulation will lead to undesirably large fluctuations in allowable cut. 2. Volume formulae are useful means of determining the yearly harvest volume, though the distribution of the cut on the ground requires definition in terms of area as well. 3. Neither area nor volume control can be used exclusively. Some combination and integration is usually necessary in actual practice. In the case of the Research Forest this can be applied most conveniently by following the area-volume computation basis. / Forestry, Faculty of / Graduate

In Europe, the origin of older Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) plantations is generally unknown. The tracing of the probable origin of one Swiss and twenty Polish Douglas-fir stands was attempted. Cone and seed characteristics were measured on material collected from all twenty-one European stands, and compared with the displayed variation of the same characteristics from Douglas-fir growing in its natural range on the Pacific Coast of North America. A seed morphology test, as described by Allen (1960), was used to indicate the Coastal or Interior origin of the samples. Based on this test, the stands from Boezingen/Switzerland and from Purda Lesna/ Poland proved both to be of Coastal origin. A direct comparison of averages of six cone characteristics (width and length of cone scale, width of bract, length of first and second prong, and rating of bract) with the ranges of averages of these characteristics as they vary in climatic seed collection zones of the natural range (Yao [1971]) did not allow an unequivocal assessment of origin. From these comparisons, it could be concluded that cone scale and bract width are more influenced by the environment than the other characteristics. The six characteristics of cone morphology, one thousand-seed weight (measured or assessed on 124 samples from the natural range) and relative DNA content (measured on thirty-six samples of the Coastal part of the natural range) were used concurrently to perform discriminant analyses based on different subspecies, climatic and latitudinal groupings. The discriminant functions obtained were then used to classify the twenty-one provenances of unknown origin. Their origin was assessed at the intersection of the groups to which they were attributed in the different analyses. The low number of provenances, when compared with the immense natural range, and the low number of characteristics taken into consideration, did not allow a complete separation of the groups of provenances. Therefore, the assessment of origin based on cone and seed morphology is still to be considered with caution. Pre-established curvilinear regressions of relative DNA content of embryo cells on latitude in both Coastal and Interior Douglas-fir (El-Lakany and Sziklai [1971, 1972]), were used for inverse estimation of the latitude of origin. It could be established, by this method, that the stand from Boezingen/Switzerland originates between lat. 44° and 47°N on the Coast. When samples are sufficient from the unknown stand, as was the case for provenance Boezingen, seed characteristics and relative DNA content gave promising indication of the probable origin. / Forestry, Faculty of / Graduate

Community and urban forestry is a multifaceted field ranging from tree planting to removal, hazard assessment, and public relations. However, the racial and gender diversity of the community forestry workforce is remarkably low. To gain a better understanding of this lack of diversity, I surveyed professionals in two major community/urban forestry organizations. Age, income, and years in the profession were considered, along with education level, to determine if there is some underlying reason for low representation of women and minorities in the community/urban forestry field. I found that while white males dominated all work sectors (especially private organizations), women were concentrated in public or non-profit organizations holding positions in offices, education, or other jobs with extensive public interaction. Minorities held similar positions to women or were in entry level jobs and general tree care rather than in more professionally advanced positions. Attitudes regarding most aspects of the profession varied little based on sex or minority status, with only minor differences on advancement potential and salary.

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No description available.

Scholars in science and technology studies have long been concerned with a variety of issues revolving around technological change, such as explaining the origins of technological innovation and arguing for or against technological determinism. This thesis reviews a number of theoretical models developed by historians, philosophers, sociologists, and other scholars to explain technological change. A case study of technological innovations in industnal forestry and timber harvesting practices provides a basis for a critique of these previously proposed models and for an argument for a new model. This model, an ecological model, suggests homeostatic pressures play a major role in the innovative processes within any technological system. / Master of Science

From the known image positional errors on aerial photographs, this thesis computes and evaluates acreage estimation errors. Four hypothetical tracts were used in simulating aerial photographs with 104 different camera orientation combinations. Flying heights of 4000 and 6000 feet, focal lengths of 24 and 50 millimeters with and without lens distortion, and tilts of 0, 3, 6, and 12 degrees were simulated. The 416 photographs were all simulated with the camera exposure station centered above the midpoint of the respective tract's bounding rectangle. The topographic relief of the tracts ranged from 19 feet in the Coastal Plain to 105 feet in the Piedmont. It was found that lens focal length did not have an independent effect on the acreage estimates. Relief error, the lowest, averaged -0.080%. In comparison, small errors in calculating scale were shown to be larger than relief errors. Tilt was recommended to be limited to six degrees, averaging +1.6% error at six degrees tilt. Because of its positive exponential nature when the tracts are centered, tilt can induce large biases. including tilts from zero to six degrees,the average was 0.634%. Lens distortion error averaged -0.686%. Overall, the average acreage error was 0.363% for simulations up to and including six degrees of tilt with and without lens distortion. This result is for centered tracts, and it was felt many of the errors were compensating given this situation. In conclusion, the photographic images can estimate areas to $1%, however, additional errors are imparted during actual measurement of the photographs. / Master of Science

A unified international method to capture, record, and report the information necessary for documenting the mechanical performance of harvesting machines and systems under specified conditions is presented. It provides a data collection method as a basis for evaluation of systems across international boundaries for better selection of machines, prior to bearing the expense of purchasing the system. An in depth study of a prototype skidder on steep terrain was conducted to test the practicality of the method. The study resulted in some modification of the been received indicating support and suggesting minimal changes. The recommendations of other reviewers will be incorporated in the final Field Manual. A microcomputer program for filing and editing the data collected in the field will be developed. / Doctor of Philosophy

<p> The Civilian Conservation Corps employed young white and black men between the ages of eighteen and twenty-five. In 1935 Robert Fechner, the Director of the Civilian Conservation Corps, ordered the segregation of Corps camps across the country. Massachusetts&rsquo; camps remained integrated due in large part to low funding and a small African American population. The experiences of Massachusetts&rsquo; African American population present a new general narrative of the Civilian Conservation Corps. The Federal government imposed a three percent African American quota, ensuring that African Americans participated in Massachusetts as the Civilian Conservation Corps expanded. This quota represents a Federal acknowledgement of the racism African Americans faced and an attempt to implement affirmative action against these hardships.</p>