ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Canadian Science Publishing
  • 1970-1974  (1,778)
  • 11
    Publication Date: 1974-09-01
    Description: Two perennial problems in the management of uneven-aged forests are considered: (i) determination of the optimal sustainable distribution of trees by diameter class, i.e. stand structure, for a given initial stocking level, and (ii) the optimal cutting schedule for the conversion of an irregular stand to a target structure. It is shown, using examples for northern hardwood stands in Wisconsin, that both problems can be solved via mathematical programming techniques. The programming approaches utilize a set of nonlinear equation models for stand table projections which consider the interdependence of size classes within the stand. To illustrate procedures, optimal stand structures are found for a case where initial stand basal area is constrained to specified levels and the objective is to maximize value growth over the cutting cycle. A conversion cutting schedule is then determined for a case in which the objective is maximization of present worth. It is emphasized that both the optimal distribution and conversion problems can be generalized to consider a broad range of objective functions, lengths of cutting cycle, and constraints on the growing stock.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Publication Date: 1973-12-01
    Description: Fertilization and cultivation before and after planting greatly increased 9-year growth and yield of longleaf (Pinuspalustris), slash (P. elliottii), and loblolly pines (P. taeda). Intensive culture did not decrease specific gravity or fiber length of the juvenile wood. In loblolly pine, genetic variation was found in response to intensive culture.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Publication Date: 1972-12-01
    Description: A factorial experiment was conducted in which Pinuscontorta var. latifolia and Piceaglauca (Moench) Voss seedlings were grown for 6 weeks under controlled environmental conditions with deficient and normal supplies of nitrate and ammonium. Free sugars (sucrose, fructose and glucose), starch (as glucose) and pectic sugars (galactose, arabinose, mannose and xylose) were quantitated. Effects of nitrogen form and nitrogen level, and their interactions, upon sugar contents and dry weights of the two species were examined. Growth responses to nitrogen occurred mainly in the shoots. For most parameters the two species reacted similarly to changes in nitrogen level and form, although the concentration of individual sugars differed between the species. In the shoots there were level × species interactions in the dry weight and the sum of free sugars plus starch. Plants grown under nitrogen deficiency were characterized by higher starch contents throughout and lower free sugars in the shoots. Supplying nitrate instead of ammonium lowered glucose levels, particularly in the shoots. Pectic sugar contents were unaffected by nitrogen nutrition. These compositional and growth responses to the nutritional regime implied changes in carbohydrate metabolism and physiological processes that are described by the C/N ratio of the plant.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Publication Date: 1972-03-01
    Description: The basic assumptions of regression analysis are recalled with special reference to the use of a logarithmic transformation. The limitations imposed on inference-making by failure to comply with these assumptions are discussed and ways to avoid the limitations indicated. A systematic bias of the order of 10 to 20% which is inherent in most, if not all, prior uses of the logarithmic equation to estimate plant biomass is noted as is the correction for the bias.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Publication Date: 1972-09-01
    Description: Calculations are presented on the quantities of N, P, K, Mg and Ca in the soil and above-ground portions of two spruce-pulpwood stands on sites of average fertility in northern and southern Quebec. The magnitude of the depletions of these nutrients from the site, in full-tree and tree-length methods of logging, are compared with the available and total quantities of them in the soil. The ranges of values, from the literature, for the input of these nutrients in dust and precipitation, and the losses in leaching, are presented and discussed in relation to the logging losses.It is concluded that on both sites it is unlikely that full-tree logging will result in any reduction in growth, due to nutrient removal, during the second rotation of trees. However, nutrient depletion due to full-tree logging, particularly with respect to Ca, K and N, may require correction by means of fertilizers in forest ecosystems of marginal fertility. These are usually either dry sites with low reserves of organic matter and low exchange capacity or wet sites with excessive accumulations of organic matter. The need for further detailed studies of the nutrient cycle in different forest ecosystems is stressed.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Publication Date: 1974-12-01
    Description: The Weibull distribution, [Formula: see text], summarized diameter, basal area, surface area, biomass, and crown profile distribution data well for several different ages of white and loblolly pine plantations. The data for diameter, basal area, surface area, and biomass were easily summarized by this one distribution in a theoretically consistent fashion. This is not possible with the normal and the gamma distributions, and the lognormal gives less satisfactory results. The distribution function should prove useful in modeling tree stands since only the parameter values need to be changed over time for the above variables. The change in these parameters may be a good way to characterize and interpret changes in stands over time.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Publication Date: 1974-12-01
    Description: A procedure is described for the separation of nine organic matter fractions from F and H horizons of forest floor materials formed under different vegetative cover. The extracts employed (and fractions obtained) were ethanol:benzene (A), dilute mineral acid (B), cold 0.1 N NaOH (H-1, F-1, F-2), and hot NaOH (H-2, F-3, F-4), with unextracted organic matter comprising the final fraction. Distribution between the fractions of carbon, and polysaccharides was investigated. Considerable variation was observed in the distribution of fractions among sites, and both between and within horizons. The significance of the fractions is discussed. It was concluded that the procedure was suitable for studying differences in distribution of organic fractions of forest floor materials, but required further modification for examination of the composition of fulvic fractions.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Publication Date: 1973-09-01
    Description: Height and diameter growth to age three and the number of first year branches were analyzed for 25 cottonwood clones grown in six plantations in central Mississippi. Plantations were on two contrasting sites and planted in three consecutive years. Results showed small clone × planting year interactions and large clone × site interactions for all parameters. In the lower Mississippi Valley, therefore, emphasis should be placed on testing over a range of sites rather than replicating over time.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Publication Date: 1973-03-01
    Description: Balsam woolly aphids were reared on young grand fir trees maintained in controlled environment or outdoors. Solutions of various nitrogen fertilizers were applied repeatedly to the trees and the effects on aphids and bark amino acids were studied. On trees fertilized with ammonium nitrate or a sequence of compounds, aphid population growth was less than on trees fertilized with urea or potassium ammonium nitrate. On urea-fertilized trees, populations multiplied 16.5 times in five generations, compared with a 5.7-fold increase on unfertilized trees and a 1.4-fold increase on ammonium nitrate-fertilized trees. These differences resulted from effects of these nutrients on aphid life history. Urea promoted aphid establishment and reproduction, whereas ammonium nitrate affected these processes, as well as survival, adversely. The highest establishment and survival rates resulted from potassium ammonium nitrate.These differences may be related to fertilizer-induced changes in the amino acid diet of the aphid. Thin layer electrophoresis and chromatography revealed that urea, ammonium nitrate, and calcium nitrate each increased arginine concentrations in the bark, the highest levels resulting from ammonium nitrate. Traces of phenylalanine and asparagine, found in other treatments, were absent from trees fertilized with ammonium nitrate during June.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Publication Date: 1972-09-01
    Description: The degree of resistance to a pulsed electric current of wood in progressive stages of discoloration and decay in living trees was correlated primarily with the moisture and mineral contents of the wood. Below the fiber saturation point, the degree of resistance was correlated primarily with the amount of moisture while above the fiber saturation point resistance was correlated primarily with the concentration of mobile potassium and calcium ions. The apparatus used to produce the current and to measure the resistance to it was accurate in detecting and in indicating the stage of deterioration of discolored and decayed wood. The apparatus was tested and found to be reliable electrically within the range of resistances encountered in the trees studied.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...