• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 26
  • 4
  • 3
  • 2
  • 2
  • 1
  • Tagged with
  • 41
  • 41
  • 24
  • 18
  • 15
  • 14
  • 13
  • 11
  • 10
  • 10
  • 8
  • 7
  • 7
  • 7
  • 6
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Site indices and rates of conversion in northern Wisconsin quaking aspen

Fralish, James S. January 1900 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
2

Estimating site productivity from non-site trees a site index based approach /

Vopicka, Charles Edward. January 2007 (has links)
Thesis (M.S.)--University of Montana, 2007. / Title from title screen. Description based on contents viewed Aug. 13, 2007. Includes bibliographical references (p. 52-53).
3

Effects of stand density on site index in thinned stands of Douglas-fir in the Pacific Northwest /

Zumrawi, Abdel Azim M. A. January 1985 (has links)
Thesis (M.S.)--Oregon State University, 1986. / Typescript (photocopy). Includes bibliographical references (leaves 38-40). Also available on the World Wide Web.
4

The Economics of management effort in planted forests: an empirical analysis of fertilization and thinning prescriptions of Pinus taeda in the US South

Sartori, Pedro J. 06 January 2021 (has links)
If a landowner‘s main objective is to maximize his/her profits from planted forest investments, questions such as when and where exactly they should fertilize, thin and clearcut must be answered. We take advantage of an experiment established in 5 different states in the US South. Forest inventory data was collected for different combinations of thinning densities where some of them received fertilization. We use the Land Expectation Value methodology where our assumptions are the infinite amount of Pine rotations while costs and stumpage prices are known and constant, and markets are perfect. One of the main results we found is that fertilization has a decreasing marginal benefit on site index quality. / M.S. / If the landowner‘s main objective is to maximize profit from forest investments, questions such as when and where they should fertilize, thin and clearcut must be answered. Fertilization‘s main objective is to provide essential nutrients for tree growth. Thinnings have two main objectives: a source of revenue in the middle of the forest rotation by selling the thinned trees and secondly to open space to the residual trees so they grown in diameter and gain value. We analyze how thinning and fertilization impact forest management from an economic perspective by checking their benefits and costs to landowners. We found that for low site index, fertilization has a positive impact in the sense its benefit is greater than the fertilization application cost. For better site indices, the opposite is true. For those who want to maximize economic benefits from planted forests. we end up with recommendations of which type of thinning and fertilization should be done according to the landowner site quality.
5

Reconstructed height growth trajectories of white spruce (Picea glauca) following deciduous release

Osika, Diana E-B Unknown Date
No description available.
6

Assessing age-height relationship using ICESat-2 and Landsat time series products of southern pines in southeastern region

Sharma Banjade, Sonia 01 December 2023 (has links)
This study investigates pine heights by age for actively managed stands in the southeastern U.S. using ICESat-2 ATL08-derived height data and maps derived from the Landsat time series. We intersected ICESat-2 ground tracks with locations of pine plantations and the Landscape Change Monitoring System (LCMS) Fast Loss product to identify previously clear-cut pine plantations. We subtracted the LCMS Fast Loss year from the date of the ICESat-2 acquisition to determine plantation age at the time of the height measurement. We stratified the data for management intensity, where stands that experience both thinning and harvesting were considered actively managed. The goal was to develop age-height relationships across the region to characterize better the impact of management on productivity and site index. This research involved the analysis of over 137,998 ICESat-2 ATL08 segments in actively managed pine stands in the U.S. Southeast. We compared a subset of ICESat-2 heights with heights derived from airborne laser scanning acquisitions (ALS) available through the USGS 3D Elevation Program. The resulting R2 was 0.82, giving us confidence in the ICESat-2 ATL08-derived forest heights. Then, through data processing and analysis, we successfully stratified the spatial patterns of ICESat-2 ATL08 heights in the southeastern region. These patterns provided insights into the distribution and variability of forest heights across the region, contributing to informed decisions in forest management. We identified some challenges in predicting pine stand age through Landsat-derived disturbance products. We found that LCMS Fast Loss labels some heavy thins as a ‘Fast Loss,’ in addition to stand-clearing disturbances like clear-cuts, adding noise to our estimation of stand age. To overcome this issue, we employed a robust model of the logarithm of heights with a reciprocal of age using a random sample consensus (RANSAC) model to calculate site indices at base age 25 (years). Our results showed the site index for the region at a base age of 25 years is 20.1 m with a model R2 of 0.91. We compared the ICESat-2-derived site index with the FIA-derived site index to see the robustness of our results. Then, the modeled site index values were used to produce a map at a base age of 25 years for the U.S. Southeast, offering insights into spatial differences in regional forest productivity. The results of this study have important implications for ecological research, forest management, and well-informed decision-making. Insights into the distribution and trends of actively managed forest heights in the Southeast are gained from studying the vast dataset, allowing for more efficient land management and conservation initiatives. In actively manage stands, our site index equation improves the ability to anticipate site productivity and estimate future timber outputs. The difficulties with age estimation that have been observed highlight the need for better methods for mapping disturbances using remote sensing in forests that use thinning as a silvicultural prescription. / US Forest Service, joint venture agreement 20-JV-11330145-037, and the USDA Mclntire-Stennis Formula Grant program, accession number 7003904, “Precision forestry for southern pine carbon monitoring.” / Master of Science
7

Estimating site susceptibility to Scotch broom dominance in young Douglas-fir plantations for control prioritization in western Washington, USA

Boyle, Grady John 11 October 2023 (has links)
Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii), a keystone species in western Washington, faces threats on plantations across this region from the invasive species Scotch broom (Cytisus scoparius (L.) Link), whose invasions on recently established stands can lead to mortality of Douglas-fir through overtopping. The susceptibility of sites to Scotch broom achieving dominance over Douglas-fir has been demonstrated as highly site dependent, however the site conditions that cause this have not yet been identified. Scotch broom has a demonstrated average maximum height of 3m, thus, after Douglas-fir exceeds this height, its risk of being overtopped is significantly reduced. This thesis strives to identify sites that were at the greatest risk Douglas-fir being overtopped by Scotch broom by first, identifying what factors improved growth of Douglas-fir during the period when they are at the greatest risk, and second, identifying factors that led to Douglas-fir outcompeting Scotch broom on sites they cohabitated. In Chapter 1, we utilized LiDAR scans, Soil Survey Geographic Database characteristics, and management histories to identify conditions that improved growth for Douglas-fir in ages 3-8. Individual tree detection was used to measure Douglas-fir heights, and a correction algorithm for LiDAR measured young Douglas-fir heights was established from field validation data. We identified that young Douglas-fir had improved growth on sites with lower elevation, flatter slopes, and finer textured soils. The factors identified were then transformed into four potential site index models based on mean stand elevation class, Mean stand elevation class and clay class, textural class and slope class, and textural class and Mean stand elevation class. In Chapter 2, we used paired field plots to examine Douglas-fir and Scotch broom competition on 19 sites across western Washington. Each site had 2 plots with only Douglas-fir and 2 plots with Douglas-fir and Scotch broom. Elevation, soil texture, and soil nutrient composition for carbon, nitrogen and available phosphorous were examined for influence on height and growth rate of both species. We identified that Scotch broom presence was negatively related to Douglas-fir height growth and that sites with either higher percentages of silt, lower concentrations of phosphorous, or higher percentages of Carbon were more likely to have growth patterns close to or exceeding Scotch broom. / Master of Science / Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) is a valuable timber species across western Washington that is commonly grown in plantations. In western Washington when Douglas-fir are planted on a site they often face competition from the invasive shrub Scotch broom (Cytisus scoparius (L.) Link). When Scotch broom invasions occur on a recently planted Douglas-fir stands, they can cause death of the trees if Scotch broom plants grow taller than the young Douglas-fir and obstruct their access to light, a process called overtopping. The risk of Douglas-fir being overtopped has been shown to be dependent on location, however what causes a location to be at risk of overtopping is yet unknown. Scotch broom has a demonstrated average maximum height of 3m, thus, after Douglas-fir exceeds this height, its risk of being overtopped is significantly reduced. This study aims to identify sites that were at the greatest risk Douglas-fir being overtopped by Scotch broom by first, identifying what sites generate the best Douglas-fir growth when they are young and at risk of being overtopped, and second, identifying site characteristics led to Scotch broom growing faster than Douglas-fir on sites they both occur on. To identify sites that produced greater young Douglas-fir height growth we used publicly available soil data from the Soil Survey Geographic Database and company management histories to predict tree heights measured through aerial laser scanning (LiDAR). We found that sites with soil textures that had higher percentages of smaller particles, were on lower elevations, and had gentler hillslopes could all produce greater Douglas-fir height growth. When attempting to identify what causes Douglas-fir to be at risk of being overtopped by Scotch broom we used plots with and without Scotch broom on a variety of field sites. This allowed us to not only identify which characteristics of sites where Douglas-fir was being outgrown by Scotch broom, but also identify if Scotch broom was changing how Douglas-fir grew. We found that reductions in Douglas-fir growth were related to Scotch broom being present and that increases in soil silt percentages, decreases in soil phosphorus concentrations, and increases in soil carbon percentages were related to Douglas-fir having height growth closer to or exceeding that of scotch broom.
8

New height growth models for western larch in British Columbia

Klinka, Karel, Brisco, David James, Nigh, Gordon D. (Gordon Donald), Chourmouzis, Christine January 2001 (has links)
Western larch (Larix occidentalis Nutt.) is a locally important species in the Nelson Forest Region, and to a lesser extent, in the Kamloops Forest Region. Its range extends from west of the Rockies to Okanagan Lake, and north to Salmon Arm, in the IDF, ICH, MS, and ESSF biogeoclimatic zones. Prior to this study, the site index curves developed for western larch in western Montana were used to model height and estimate site index in British Columbia. It has been suggested that these curves may not adequately reflect the height growth patterns of western larch in BC. Differences could arise from genetics, different methods of selecting sample trees, or climatic differences. The objective of this project was to produce accurate height growth models for western larch in BC.
9

Skötsel av klibbal för produktion av efterfrågad virkeskvalitet / Silviculture of common alder for production of sought-after timber quality

Runesson, Anna January 2016 (has links)
Klibbalen (Alnus Glutinosa) växer på frisk eller fuktig mark i södra och mellersta Sverige, mestadels i bestånd mindre än ett hektar. Klibbalen är med sina kvävefixerande noduler på rötterna ett näringsberikande träd, dess kvävetillförsel medför en naturlig gödsling. Den växer som bäst på djup näringsrik, mullrik mark med rörligt grundvatten. Produktionen kan  uppgå till drygt 10 m3sk/ha och år och kan föryngringsavverkas vid 35 års ålder. Virket är mjukt, har låg densitet och är lätt att bearbeta. Efter bearbetning fås en jämn fin yta som behålls även efter återfuktning. Värmeupptagningsförmågan är låg för klibbal. Däremot är virket inte intressant för tillverkning av papper då virket missfärgar pappersmassan. Undersökningen är tredelad, besök och intervjuer på lövsågverk, fältmätningar i bestånd samt analys av beståndsdata från skogsbruksplaner. Dessa tre delar ligger till grund för en syntes till en förbättrad skötselinstruktion för klibbal. Vid intervjuer med lövsågverk framkommer att de sågverk som idag sågar lövvirke upplever en brist på virke med rätt kvalitet. Med bättre skötsel och ett anpassat skötselprogram för klibbal bör det gå att få ut mer sågbart virke. God kvalitet på klibbalsvirke definieras som virke fritt från torr- och rötkvist samt brunkärna. Träden bör vid slutavverkning vara 30 till 40 cm i brösthöjd. De skogsbruksplaner som Södra Skogsägarna tillhandahöll har undersökts avseende de bestånd där klibbal är huvudträdslag. Som regel baseras skötselförslagen för dessa bestånd på andra trädslag än klibbal t.ex. gran eller björk och med ett skötselintervall på 5 år. Skötselintervallet blir ofta för långt i dessa förslag. Resultatet från såväl intervjuerna, fältmätningarna och skogsbruksplanerna har syntetiserats till ett förbättrat skötselprogram. Med en korrekt angivning av beståndsdata med anpassande skötselförslag för klibbal som har korta skötselperioder går det att skapa bättre framtida virkeskvalitet. Dagens skogsbruksplaner ger för långa tidsperioder för klibbalskötsel och bör förkortas till 2, 3 och 4-års långa perioder beroende på var i omloppstiden man befinner sig. / Common alder (Alnus Glutinosa) grows for the most part in the south and middle of Sweden, in clumps smaller than one hectare. The wood is soft, light and easy to work and maintains a smooth surface in humid environment and does not take on heath. The wood is not of interest in pulp as it discolors. The hard wood saw mills have at present a lack of good quality hardwood. With enhanced silviculture-program for common alder with shorter silviculture-interval, 2-, 3 and 4 years, and the use of a site index for common alder it should be possible to get a higher production of good quality hardwood. The current silviculture programs should be changed to shorter intervals to fit common alder silviculture. When common alder is identified for cutting, it should be taken to the hard wood industry for optimal refining.
10

Relationship of site index to estimates of soil moisture and nutrients for western redcedar in south coastal British Columbia

Klinka, Karel, Kayahara, Gordon J., Chourmouzis, Christine January 1997 (has links)
Where timber production is the primary management objective, knowledge of the relationship between the potential productivity of candidate tree species and levels of light, heat, nutrient, moisture and aeration is necessary for species- and site-specific decision making. For example, foresters need to decide which tree species to regenerate on a particular harvested area to obtain maximum sustainable productivity. Similarily, when considering the application of silvicultural treatments such as spacing or fertilizing, foresters need to determine whether the potential productivity of a particular site warrants the cost of the treatment. We used the site index (height of dominant trees at breast height age) of western redcedar (Thuja plicata Donn. ex D. Don.) as a measure of productivity, and described the pattern of mean site index in relation to field identified soil moisure and soil nutrient regimes.

Page generated in 0.0455 seconds