Knowledge of the potential productivity of a tree species becomes especially important when timber production is the primary management objective. However, direct determination of potential productivity is often not possible. For example, in situations where the site is unstocked, stocked with trees unsuitable for productivity measurement, or stocked with species other than the one of interest. In these cases, an indirect estimate using known characteristics of the site itself is required. Such estimates were made using regression to model site index with indirect measures of site quality for lodgepole pine (Pinus contorta) and interior spruce (Picea engelmannii × P. glauca) in the Sub-Boreal Spruce (SBS) zone of central BC. We tested the utility of these productivity relationship models for predicting the site index of lodgepole pine and interior spruce (Kayahara et al. accepted for publication).

Hållbart skogsbruk kräver kunskap om skogens tillstånd i nutid samt tänkbara framtida åtgärder. Syftet med studien var att undersöka om det via digitala flygbilder var möjligt att skatta trädålder och SI på beståndsnivå, samt med vilken precision det kan utföras.Endast tall- och/ eller grandominerade bestånd, valdes i Vetlanda och Nybro kommun. Flygbilderna bearbetades av Foran Sverige AB med hjälp av ett program framtaget av Spacemetric AB.De fältinventerade beståndens data jämfördes med medianvärden från de skattade trädhöjderna, vilka matades in i en formel, konstruerad för att göra en kurvanpassning mot de nya höjdutvecklingskurvorna.Metoden för framtagning av höjdvärden via bildmatchning bör förfinas, t.ex. bör laserskanningen bidra med högre precision. Endast mindre delar av landet har mer än en skanningstidpunkt med laser, metoden kräver minst två höjdvärden i serie.Syftet med studien anses uppfyllt, dock hade studien tjänat på en bättre metod för att sålla bort felaktiga data innan analys. Generaliserbarheten är god på liknande bestånd, vidare studier krävs för att kunna påvisa en användarbarhet i olika typer av bestånd, där även olika skötselvarianter bör vägas in.

Syftet med studien var att följa upp resultatet från maskinell sådd av tall efter 1-3 växtsäsonger och ge förståelse för vilka parametrar som har störst påverkan på såddresultatet. Studien gjordes genom att göra fältinventering på 17 lokaler föryngrade med maskinell sådd från åren 2016-2018 belägna i trakterna av Växjö, Vimmerby och Skövde.Resultaten visar att 47 % av sådderna uppfyller Skogsstyrelsens föreskrifter för plantantal och nollytor vid föryngring. Nollytor är största anledningen till att föryngringar inte klarar kraven.Plantantalet ökade med ökande antal fröträd och ståndortsindex och mindre konkurrens av övrig markvegetation.Nederbördsmängd var ingen begränsande faktor för högt plantantal. Angående temperatursumman under vegetationsperioden gick det inte att påvisa påverkan på såddens resultat.2 % av plantorna hade betesskador och betesskadorna ökade med planthöjden upp till 40 centimeter.

In the upland hardwood forests of the southern Appalachians, management tools are needed based on the characteristics of the site to quantify the site quality where no accurate maps of site quality exist. Three studies were conducted to achieve this objective. The first study tested if independent measures of forest productivity, based on vegetation and environment, in a six-county study area in the Blue Ridge Mountains in North Carolina would correlate with measures of forest productivity obtained from U.S. Forest Service Forest Inventory Analysis (FIA) data. Specific hypotheses included: FIA measures of forest productivity are related to one another; FIA measures of forest productivity are related to FIA-measured landscape parameters; and FIA measures of forest productivity are related to independent measures of forest productivity based on landscape parameters and soil characteristics. Four predictive indices of forest productivity were used; three were generated in a geographic information system (GIS). FIA measures of forest productivity were not significantly correlated to FIA measured landscape parameters. FIA site productivity classes were significantly correlated to FIA measures of site index. Independent measures of forest productivity, particularly the Moisture Regime Index (MRI) and the Forest Site Quality Index (FSQI), were significantly correlated to FIA measures of site index. Topography can be used to delineate site quality, but the addition of soil depth can prove to be useful in the estimation. The second study was designed to develop methods, based on field and digital data, to identify colluvial soils in the central Ridge and Valley of southwestern Virginia. Two hypotheses were tested. First, on the linear side slopes of the study area, where site quality is low in stands with subxeric to xeric moisture regimes, vegetation and topography can indicate colluvial soils. A second hypothesis tested if the topographic signature of colluvial soils could be identified geospatially with a digital elevation model. Results indicated that the MRI and the Terrain Shape Index predicted the presence of colluvial deposits in the study area. The basal area of yellow-poplar was positively associated with colluvial soils. A GIS-based model found the slope difference of colluvial soils to be less steep than residual soils as the size of the neighborhood increased. The final study determined if measures of site quality in the Blue Ridge Mountains of North Carolina were related to the water budget. Specifically,the hypothesis that site index could be predicted by variables that represented the inputs, usage, and supply of water was tested. A second hypothesis questioned if site quality classes could be predicted by a combination of topography and the annual water budget. Regression models predicted site index to be a function of topography, available water supply, and the annual water budget, but the accuracy was low (R2=0.11 and 0.13). A classification approach yielded better results. Incorporating the annual water budget into the FSQI increased classification accuracy of predicted site index by 50%, and decreased the number of sites misclassified by one class by 8%. Where accurate maps of site quality do not exist, the MRI, the abundance of yellow-poplar, and the modified FSQI may be used to delineate site quality for site-specific management and, ultimately, greater return on investment for the landowner. / Ph. D.

Detecting climate-induced effects in forest ecosystems become increasingly important as more evidence of greenhouse-gas-related climate change were founded. The Forest Vegetation Simulator (FVS) is an important growth and yield model used to support management and planning on public forest lands over the southern United States, however its prediction accuracy was challenged due to its climate- insensitive nature. The goal of this study was to develop species-specific prediction models for eastern U.S. forest tree species with climate and soil properties as predictors in order to incorporate the effects of climate and soils-based variables on forest growth and yield into FVS-Sn. Development of climate- sensitive models for site index, individual-tree mortality and diameter increment were addressed separately, which were all developed using Random Forests on the basis of USDA Forest Service Forest Inventory and Analysis program linked to contemporary climate data and soil properties mapped in the USDA Soil Survey Geographic SSURGO database. Results showed climate was a stronger driver of site index than soils. When soils and climate were used together, site index predictions for species grouped as conifers or hardwoods were almost as precise as species-specific models for many of the most common eastern forest tree species. Model comparison was conducted to pursue the most suitable individual-tree mortality prediction model for 20 most important species among Logistic Regression, Random Forests, and Artificial Neural Networks. Results showed that Random Forests with all indicators involved generally performed well, especially sound for species with medium and high mortality. At a chosen threshold, it frequently achieved the equally highest value of sensitivity and specificity among chosen candidates. To evaluate the prediction ability of Random Forests model on individual-tree diameter increment, Multiple Linear Regression model was built as baseline on each of most common 20 species eastern U.S. area. Comparison results showed that Random Forests gained advantages in model validation and future projection under climate change. Using the developed climate-sensitive models, multiple maps were produced to illustrate how forest tree growth, yield, and mortality of individual tree may change in the eastern U.S. over the 21st century under several climate change scenarios. / Ph. D.

Equations for modeling the height-age pattern of forest trees or stands are typically developed for a given species in a specified region. In order to adequately model height-age patterns, the resulting equations are often quite complex. This study addresses the question of how to increase the accuracy and precision of the prediction of height-age relationships through the use of localized equations. Although the pattern of height-age relationships of loblolly pine plantations was studied, the methodology should prove valuable for other species as well. The Schumacher logarithm of height-reciprocal of age model was fitted to data from loblolly pine plantations to attain an average guide curve. Various methods of localizing this equation to a particular stand were examined. The methods are based on empirical Bayesian, maximum likelihood, and Kalman filter theory. All of these methods employ the general concept of feedback in localizing the simple equation. The best of these various models is compared with the unadjusted model and a more complex polymorphic equation. The adjusted model compares favorably with these other two models. / Master of Science

No description available.

When making decisions on which areas to harvest in a sustained yield, even-flow manner in mountainous areas such those in coastal British Columbia, it is important to know how timber productivity changes with elevation. This information allows foresters to decide at what elevation to start increasing the rotation age and to decide at what elevation sustainable harvesting becomes infeasible due to low productivity. Since Pacific silver fir (Abies amabilis Dougl. ex Forbes) has an elevation range that extends from sea level nearly to the tree line (0 m to approximately 1,650 m; from the Coastal Western Hemlock zone, through the Mountain Hemlock zone; to the lower limits of the Alpine Tundra zone), productivity-elevation relationships are especially important. To acquire quantitative measures of productivity decrease with increasing elevation a regression equation relating site index (the height of the dominant trees at a base age of breast height age of 50 years) to elevation in southern coastal BC was developed. In turn, we used this regression as an input into the height driven yield model named the Variable Density Yield Prediction model (VDYP). The use of the VDYP model allows the site index values to be translated into actual productivity measures (e.g., volume per hectare, mean annual increment at culmination age).

The influence of salal on tree growth has attained considerable attention in coastal British Columbia. Field observations, surveys, and studies in the CWH zone have indicated poor growth performance of crop tree species in salal-dominated plantations and natural immature and old-growth stands. Where sites have been burned and planted, tree growth has improved; similar effects have been observed for naturally regenerated stands. Immature stands that developed after wind disturbance or harvesting feature rapid growth and nearly complete absence of salal. As studies have shown that ericaceous plants negatively impact tree growth, the salal on potential harvest sites has been considered undesirable. This study examined (1) the possible influence of salal on the stand, soil nutrient status and site index, and (2) the relations between site index, salal, plant communities, and site in disturbed, immature, coastal Douglas-fir ecosystems. We compared vegetation and environmental characteristics of 101 ecosystems, and examined differences in foliar and soil nutrient characteristics and site index between stands with high and low salal cover through analysis of variance (ANOVA) and regression analysis.

A silviculturist needs to know how productivity of all tree species under management varies with the ecological determinants of site quality, i.e., the environmental factors that directly affect the growth of plants - light, heat, soil moisture, soil nutrients, and soil aeration. A good understanding of this variation is necessary for making biologically viable, speciesand site specific silvicultural decisions. Productivity of a given species is usually measured by site index (top tree height at 50 years at breast height age). Quantified relationships between site index of a given species and ecological measures of site quality provide predictive models for estimating site index for all sites on which the species may grow. Western larch (Larix occidentalis Nutt.) is an important tree species in southern central and eastern British Columbia. It grows mainly in the IDF, ICH, and MS zones on moderately dry through very moist sites and on poor through very rich sites. In view of this relatively wide ecological amplitude, a large variation in productivity could be expected. In the study summarized here, relationships between larch site index and selected ecological measures of site quality were examined, and a site index model using these measures as predictors was developed.