scholarly journals Maximum Stand-Density Index of 40 Western Hemlock–Sitka Spruce Stands in Southeast Alaska

2007 ◽  
Vol 22 (2) ◽  
pp. 99-104 ◽  
Author(s):  
Nathan J. Poage ◽  
David D. Marshall ◽  
Michael H. McClellan
Keyword(s):  
Basal Area ◽  
Stand Density ◽  
Site Factors ◽  
Southeast Alaska ◽  
Spruce Stands ◽  
The Mean ◽  
Stand Density Index ◽  
Over Time ◽  
Stand Basal Area ◽  
Species Proportion

Abstract Reineke's (1933) maximum stand-density index (SDImax) was determined for 40 unthinned, fully stocked, even-aged, hemlock-spruce stands in southeast Alaska. A nonlinear model was used to identify objectively the linear portions of the stands' self-thinning trajectories for analysis. The objectives of the present study were (1) to use the modeled slopes and intercepts to determine the mean SDImax of the stands and (2) to identify stand and site factors associated with the variability observed in SDImax. The mean SDImax of the 40 hemlock-spruce stands in southeast Alaska was 619. Individually, none of the stand or site factors examined accounted for >30% of the variability observed in SDImax when all 40 stands were analyzed together. Although the spruce proportion of total stand basal area of most stands increased over time and the hemlock proportion of total stand basal area of most stands decreased over time, SDImax was not related to species proportion or changes in species proportion over time.

scholarly journals A Retrospective Assessment of Partial Cutting to Reduce Spruce Beetle-Caused Mortality in the Southern Rocky Mountains

2010 ◽  
Vol 25 (2) ◽  
pp. 81-87 ◽  
Author(s):  
E. Matthew Hansen ◽  
José F. Negron ◽  
A. Steven Munson ◽  
John A. Anhold
Keyword(s):  
Bark Beetle ◽  
Basal Area ◽  
Stand Density ◽  
Population Pressure ◽  
Partial Cutting ◽  
Degree Of Protection ◽  
Southern Rocky Mountains ◽  
Retrospective Assessment ◽  
Spruce Stands ◽  
Stand Density Index

Abstract Tree susceptibility to bark beetle-caused mortality has been linked to stand characteristics such as basal area (BA) and average tree size, factors that can be manipulated through partial cutting. There is no experimental evidence, however, demonstrating the efficacy of partial cutting in spruce type. Such experiments are very difficult to complete because of the inability to manipulate bark beetle populations needed to challenge treated stands. To circumvent this difficulty, we identified spruce stands that were partially cut (for nonexperimental reasons) in advance ofbeetle activity and compared beetle-caused mortality to that in nearby spruce stands that were not treated. Treated stands had fewer infested stems and less infested BA than untreated stands, as well as smaller proportions of infested stems and BA. Untreated stands, however, had more residualspruce stems and BA than treated stands. Most of this difference was among stems 3–11 in. dbh with little difference in survivorship among larger stems. Spruce regeneration was not significantly different among treated and untreated stands. Spruce stand density index, spruce BA, and the number of spruce stems >11 in. dbh were the stand variables most strongly correlated with host mortality measurements. Insect population pressure appears to influence the degree of protection to residual spruce following partial cutting.

scholarly journals Use of Modified Reineke’s Stand Density Index in Predicting Growth and Survival of Chinese Fir Plantations

2019 ◽  
Vol 65 (6) ◽  
pp. 776-783 ◽  
Author(s):  
Xiongqing Zhang ◽  
Quang V Cao ◽  
Lele Lu ◽  
Hanchen Wang ◽  
Aiguo Duan ◽  
...  
Keyword(s):  
Predictor Variable ◽  
Basal Area ◽  
Stand Density ◽  
Chinese Fir ◽  
The Self ◽  
Survival Models ◽  
Future Climate Change ◽  
Growth And Survival ◽  
Density Index ◽  
Stand Density Index

Abstract Stand density index (SDI) has played an important role in controlling stand stocking and modeling stand development in forest stands. Reineke’s SDI (SDI_R) is based on a constant slope of –1.605 for the self-thinning line. For Chinese fir plantations, however, it has been reported that the self-thinning slope varied with site and climate, rendering SDI_R questionable. Remeasured data from 48 plots distributed in Fujian, Jiangxi, Guangxi, and Sichuan provinces were used to develop models for prediction of stand survival and basal area, with SDI_R incorporated as a predictor variable. Also included in the evaluation were growth models based on self-thinning slopes estimated from two groups of sites (SDI_S) or from climate variables (SDI_C). Results indicated that models with climate-sensitive SDI (SDI_C) performed best, followed by SDI_S and SDI_R. The control models without SDI received the worst overall rank. Inclusion of climate-sensitive SDI in growth and survival models can therefore facilitate modeling of the relation between stand density and growth/survival under future climate-change conditions.

scholarly journals Vertical Point Sampling with a Camera

2011 ◽  
Vol 28 (2) ◽  
pp. 61-65 ◽  
Author(s):  
Mark J. Ducey ◽  
John A. Kershaw
Keyword(s):  
Basal Area ◽  
Stand Density ◽  
Double Sampling ◽  
Point Sampling ◽  
Field Techniques ◽  
Potential Applications ◽  
Stand Density Index ◽  
Detectable Bias ◽  
Horizontal Point Sampling

Abstract Vertical point sampling has seen relatively little use in practical forestry, in part because existing field techniques are difficult. We show how vertical point sampling can be implemented quickly and easily using a camera. We give tables and equations for calculating the height-squared factor, which plays a role similar to that of the basal area factor in horizontal point sampling. Some suggestions for choosing a height-squared factor are discussed, along with potential applications for further exploration. We illustrate the technique using a case study in southern Maine. Direct estimates with no statistically detectable bias were obtained using height-squared factors greater than 3. The results also suggested that the technique could be used as a correlate in double sampling for variables such as cubic volume, stand density index, and biomass, and possibly board foot volume as well.

scholarly journals Site factors and stand conditions associated with Persian oak decline in Zagros mountain forests

2018 ◽  
Vol 26 (3) ◽  
pp. e014 ◽  
Author(s):  
Ahmad Hosseini ◽  
Seyed M. Hosseini ◽  
Juan C. Linares
Keyword(s):  
Climate Change ◽  
Tree Mortality ◽  
Stand Structure ◽  
Basal Area ◽  
Stand Density ◽  
Change Scenario ◽  
Climate Trends ◽  
Site Factors ◽  
Main Hypothesis ◽  
Shallow Soils

Aim of study: Drought and stand structure are major and interconnected drivers of forest dynamics. Water shortage and tree-to-tree competition may interact under the current climate change scenario, increasing tree mortality. In this study, we aimed to investigate climate trends, site and stand structure effects on tree mortality, with the main hypothesis that drought-induced mortality is higher as competition increases.Area of study: Persian oak forests from Zagros Range, western Iran.Material and Methods: We split the study area into 20 topographical units (TUs), based on aspect, slope and elevation. In each TU, three 0.1 ha plots were established to quantify site and stand characteristics, namely the diameter of all trees and shrubs, stand density and basal area, canopy dieback and mortality. In addition, soil profiles were analyzed to obtain physical and chemical soil properties. Six transects 100 m length were established per TU to measure tree-to-tree competition for alive and dead trees.Main Results: The highest mortality rates and crown dieback were found at higher elevations and southern and western aspects. Our findings confirm increasing rates of tree mortality in stands with higher tree density and shallow soils. As regard links between climate change and forest decline, our results suggest that changing forest structure may have a significant impact on dust emission.Research highlights: Despite severe dry years occurred recently the study area, they are not significantly different than those recorded in the past. Stand structure appears as a modulating factor of climate change effects, linked to competition-related tree vulnerability to drought.

scholarly journals Rapid Assessment of Relative Density in Mixed-Species Stands of the Northeastern United States

2010 ◽  
Vol 2010 ◽  
pp. 1-8
Author(s):  
M. J. Ducey ◽  
R. A. Knapp
Keyword(s):  
United States ◽  
Specific Gravity ◽  
Rapid Assessment ◽  
Basal Area ◽  
Stand Density ◽  
Sampling Technique ◽  
Northeastern United States ◽  
Mixed Species ◽  
Stand Density Index ◽  
Simple Tree

Basal area has shortcomings as a measure of stand density, but it is often preferred for operational assessments because it is easy to measure. Previous work has demonstrated that an additive version of Reineke's stand density index can be estimated by a simple tree count using a modified horizontal point sampling technique. We show that this technique can be extended further to estimate a mixed-species density measure that has been developed for complex stands in the northeastern United States, using wood specific gravity to harmonize the density contributions of different species. The sampling technique provides design-unbiased estimates of stand density from a weighted tree count, where the weights depend on specific gravity but not on diameter. Rounding the specific gravity values for different species in the calculation of estimates introduces a trivial amount of bias but streamlines the procedure for rapid use in the field.

Testing the Lake States variant of FVS (Forest Vegetation Simulator) for the main forest types of northern Ontario

2004 ◽  
Vol 80 (4) ◽  
pp. 495-506 ◽  
Author(s):  
V. Lacerte ◽  
G R Larocque ◽  
M. Woods ◽  
W J Parton ◽  
M. Penner
Keyword(s):  
Black Spruce ◽  
Basal Area ◽  
Stand Density ◽  
Site Index ◽  
Forest Vegetation ◽  
Forest Vegetation Simulator ◽  
Consistency Analysis ◽  
Northern Ontario ◽  
Individual Tree ◽  
Stand Basal Area

The Lake States variant of the FVS (Forest Vegetation Simulator) model (LS-FVS), also known as the LS-TWIGS variant of FVS, was validated for black spruce (Picea mariana (Mill.) BSP), white spruce (Picea glauca (Moench) Voss), jack pine (Pinus banksiana Lamb.) and trembling aspen (Populus tremuloides Michx.) forests in northern Ontario. Individual-tree data from 537 remeasured sample plots were used. This dataset included different combinations of site index, stand density and age. It was possible to compare observations and predictions for different projection length periods. The validation exercise included a biological consistency analysis, the computation of mean percent difference (MPD) for stand density, stand basal area, top height and quadratic mean diameter (QMD) and the comparison of observed and predicted individual-tree dbh. The biological consistency analysis indicated that LS-FVS logically predicted the effect of site index on top height, stand basal area and QMD for black spruce and jack pine. However, the decrease in stand basal area at young ages was inconsistent with the normal development pattern of the forest stands under study and was attributed to deficiencies in the prediction of mortality. LS-FVS was found to underpredict stand density, stand basal area and top height and to over-predict QMD. Even though there were large errors in the prediction of change in stand density, LS-FVS was nevertheless consistent in the prediction of the shape of the dbh size distribution. Key words: FVS, Forest Vegetation Simulator, validation, biological consistency analysis

scholarly journals The relationship between volume increment and stand density in Norway spruce plantations

2020 ◽  
Author(s):  
Micky Allen ◽  
Andreas Brunner ◽  
Clara Antón-Fernández ◽  
Rasmus Astrup
Keyword(s):  
Norway Spruce ◽  
Basal Area ◽  
Stand Density ◽  
Management Objectives ◽  
Wide Range ◽  
Volume Increment ◽  
Basic Relationship ◽  
Stand Density Index ◽  
The Relationship ◽  
Experimental Plots

Abstract An understanding of the relationship between volume increment and stand density (basal area, stand density index, etc.) is of utmost importance for properly managing stand density to achieve specific management objectives. There are two main approaches to analyse growth–density relationships. The first relates volume increment to stand density through a basic relationship, which can vary with site productivity, age, and potentially incorporates treatment effects. The second is to relate the volume increment and density of thinned experimental plots relative to that of an unthinned experimental plot on the same site. Using a dataset of 229 thinned and unthinned experimental plots of Norway spruce, a growth model is developed describing the relationship between gross or net volume increment and basal area. The models indicate that gross volume increases with increasing basal area up to 50 m2 and thereafter becomes constant out to the maximum basal area. Alternatively, net volume increment was maximized at a basal area of 43 m2 and decreased with further increases in basal area. However, the models indicated a wide range where net volume increment was essentially constant, varying by less than 1 m3 ha−1 year−1. An analysis of different thinning scenarios indicated that the relative relationship between volume increment and stand density was dynamic and changed over the course of a rotation.

scholarly journals Effects of Western Balsam Bark Beetle on Spruce-Fir Forests of North-Central Wyoming

2003 ◽  
Vol 18 (4) ◽  
pp. 259-266 ◽  
Author(s):  
Joel D. McMillin ◽  
Kurt K. Allen ◽  
Daniel F. Long ◽  
Jeri Lyn Harris ◽  
José F. Negrón
Keyword(s):  
Bark Beetle ◽  
Basal Area ◽  
Stand Density ◽  
Herbaceous Plant ◽  
North Central ◽  
Subalpine Fir ◽  
Dryocoetes Confusus ◽  
Density Index ◽  
Stand Density Index ◽  
Stand Conditions

Abstract Western balsam bark beetle, Dryocoetes confusus (Coleoptera: Scolytidae), has caused widespread mortality of subalpine fir (Abies lasiocarpa) in western North America throughout the past decade. The objectives of this study were to document the effects of this mortality, relate mortality to pre-existing stand conditions, and investigate the role of storm-damaged fir in beetle population dynamics in north-central Wyoming. Transect cruise lines and pairs of infested and uninfested plots were installed to detect changes in the forest overstory and understory and to determine associations between stand conditions and beetle-caused fir mortality. On average, beetles killed more than 70 trees/ac over the last several years. This mortality resulted in significant decreases in: subalpine fir basal area, trees per acre, stand density index, and the percentage of subalpine fir stems in the overstory. Small, but significant increases were detected in the understory; herbaceous plant abundance increased in the infested plots compared with the noninfested plots. Moreover, significant positive linear relationships were found between the amount of fir mortality and the percentage of subalpine fir trees in a stand, subalpine fir basal area, and subalpine fir stand density index. In addition, a significant positive linear relationship was found between the percentage of wind-caused downed fir logs in an area and the percentage of logs utilized by western balsam bark beetle. The blowdown events that occurred in the mid-1990s in combination with a high percentage of fir component has provided ideal conditions for continued beetle expansion. West. J. Appl. For. 18(4):259–266.

Double Sampling Increases the Efficiency of Forest Floor Inventories for Arizona Ponderosa Pine Forests

1994 ◽  
Vol 4 (1) ◽  
pp. 3 ◽  
Author(s):  
PZ Fule ◽  
WW Covington
Keyword(s):  
Ponderosa Pine ◽  
Basal Area ◽  
Stand Density ◽  
Cost Effective ◽  
Pine Forests ◽  
Double Sampling ◽  
Fuel Loading ◽  
Size Classes ◽  
Ponderosa Pine Forests ◽  
Stand Density Index

Stand and natural fuel conditions were sampled in ponderosa pine forests in northern and central Arizona to develop predictive fuel depth and loading equations. Litter and duff depths can be estimated from measurements of stand density (basal area, stand density index). Although woody fuel loading did not correlate well with stand variables, correlations were found among loadings of different woody fuel size classes, so that results from a planar intersect tally of certain single woody fuel size classes may be used to predict the loadings in certain other size classes. The relatively low precision of estimates from these predictive equations can be substantially increased by applying them in a double sampling scheme. Making use of these predictive relationships, managers can devise simple, rapid, arid cost-effective fuel inventories that focus on the fuel category of interest. Fuel loads can be estimated at a desired precision with reduced investment of time and funds compared to a more comprehensive direct fuel inventory.

Baldcypress height–diameter equations and their prediction confidence intervals

1992 ◽  
Vol 22 (9) ◽  
pp. 1429-1434 ◽  
Author(s):  
Bernard R. Parresol
Keyword(s):  
United States ◽  
Confidence Intervals ◽  
Nonlinear Regression ◽  
Basal Area ◽  
Confidence Bands ◽  
Bald Cypress ◽  
Prediction Confidence ◽  
Independent Variable ◽  
The Mean ◽  
Stand Basal Area

Height–diameter relationships are an important component in yield estimation, stand description, and damage appraisals. A nonlinear exponential function used extensively in the northwest United States was chosen for bald cypress (Taxodiumdistichum (L.) Rich.). Homogeneity and normality of residuals were examined, and the function as well as the mean and individual prediction confidence bands were plotted. The inclusion of stand basal area as an additional independent variable provided a better fit to the data. The paper is concluded with a section on construction and use of simple and joint confidence intervals about the mean and individual predictions from the nonlinear regression.

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