Comparison of stochastic and deterministic mortality estimation in an individual tree based stand growth model

1986 ◽  
Vol 16 (5) ◽  
pp. 1139-1141 ◽  
Author(s):  
Laura A. Weber ◽  
Alan R. Ek ◽  
Terry D. Droessler
Keyword(s):  
Growth Model ◽  
Basal Area ◽  
Deterministic Approach ◽  
Projection Model ◽  
Individual Tree ◽  
Stand Growth ◽  
Mortality Estimation ◽  
Stochastic Mortality ◽  
Growth Projection

Long-term projections (100 years) were made using the deterministic and stochastic mortality algorithms of the STEMS individual tree based stand growth projection model. Deterministic versus averaged stochastic projection results showed no practical differences in mean stand values for number of trees, basal area, volume, or diameter distributions. The deterministic approach also eliminates the need for making repeated stochastic runs and averaging the results where interest lies only in mean projected values.

Construction of a stand growth model utilizing photosynthesis and respiration relationships in individual trees

1988 ◽  
Vol 18 (8) ◽  
pp. 1027-1035 ◽  
Author(s):  
Risto Sievänen ◽  
Thomas E. Burk ◽  
Alan R. Ek
Keyword(s):  
Growth Model ◽  
Basal Area ◽  
Preliminary Evaluation ◽  
Growth Data ◽  
Individual Tree ◽  
Stand Growth ◽  
Long Term Trends ◽  
Using Data ◽  
Individual Trees ◽  
Photosynthesis And Respiration

A discrete growth model for an individual tree in a forest stand is presented. The model is based on simplified photosynthesis and respiration relationships. Implementation of the model also requires functions for change in live crown ratio and stems per unit area. Tree growth predictions are expressed in terms of biomass and basal area. A preliminary evaluation of the model is made using data from the literature on the growth of even-aged stands of red pine (Pinusresinosa Ait.). The model produced both short- and long-term trends consistent with stand growth data. The evaluation suggests further possibilities for model component refinement.

Effects of measurement errors on an individual tree-based growth projection system

1984 ◽  
Vol 14 (3) ◽  
pp. 311-316 ◽  
Author(s):  
George Z. Gertner ◽  
Paul J. Dzialowy
Keyword(s):  
Measurement Errors ◽  
Basal Area ◽  
Monte Carlo Study ◽  
Site Index ◽  
Projection Model ◽  
Individual Tree ◽  
Projection System ◽  
Random Measurement ◽  
Input Variables ◽  
Growth Projection

Systematic and random measurement errors were placed on the input variables of a distance-independent individual tree-based growth and mortality projection model to study how sensitive the system was to measurement error. The study was conducted in three parts. First, the effects of systematic measurement errors on individual model components of the growth projection were investigated. Second, systematic errors were placed on the input variables of the growth projection system and the performance of the overall system was observed. Third, a Monte Carlo study was performed to examine the effects of random measurement errors of varying magnitude on the projection system estimates. Overall, the projection system was most sensitive to measurement errors in site index. Measurement errors in diameter at breast height were only critical when projecting basal area, but were not critical when projecting number of trees. The system was insensitive to errors in crown ratio.

scholarly journals Plot, stand, and cover-type aggregation effects on projections with an individual tree based stand growth model

1981 ◽  
Vol 11 (2) ◽  
pp. 310-316 ◽  
Author(s):  
Melinda Moeur ◽  
Alan R. Ek
Keyword(s):  
Growth Model ◽  
Stand Structure ◽  
Basal Area ◽  
Average Diameter ◽  
Red Pine ◽  
Individual Tree ◽  
Projection System ◽  
Stand Growth ◽  
Cover Type ◽  
Independent Individual

A distance-independent, individual tree based growth model (the multipurpose forest projection system (MFPS)) was used to project changes in stand structure on aspen, red pine, and jack pine cover types in northern Minnesota for 37 years. Individual 0.058-ha plot projections, projections of plots aggregated within stands, and projections of plots aggregated within cover types were compared with each other and with observed plot conditions. Actual plot observations were available for up to 17 years. Individual plot, stand, and cover-type aggregations produced very similar projections in terms of number of trees, average diameter, basal area, and biomass. Plot by plot projections were most accurate in comparison with observed conditions, followed by stand and then cover-type aggregations. Differences from actual values and among projections generally increased with longer projections.

STEMS Model Projection Capability with Incomplete Tree List Input Data

1988 ◽  
Vol 5 (3) ◽  
pp. 190-194 ◽  
Author(s):  
Bryan L. Randall ◽  
Alan R. Ek ◽  
Jerold T. Hahn ◽  
Roland G. Buchman
Keyword(s):  
Input Data ◽  
Basal Area ◽  
Size Class ◽  
Small Tree ◽  
Projection Model ◽  
Individual Tree ◽  
Stand Growth ◽  
Tree Distribution ◽  
Highly Sensitive ◽  
Volume Estimates

Abstract Projections were made using the STEMS individual tree based stand growth model for plots in red pine, maple-birch, and aspen cover types for periods up to 50 years. Effects of incomplete tree list input data on plots in the form of small tree censorship (omission of small trees) and tree list aggregation (by size class) were examined by comparing projections made for complete plot tree lists (controls) with projections made after these tree lists were censored and aggregated (treatments). Basal area and number of trees estimates proved highly sensitive to censorship, while volume estimates were much less sensitive. Augmentation of censored distributions by an “average” small tree distribution for the cover type resulted in significant improvement of these estimates. Projection model capability using input data aggregated by size class depended on the degree of aggregation. For some types of aggregation, for example by 2-in. dbh classes, the STEMS model retains much of its predictive utility. North. J. Appl. For. 5:190-194, Sept. 1988.

Assessing model performance in forecasting long-term individual tree diameter versus basal area increment for the primary Acadian tree species

2011 ◽  
Vol 41 (12) ◽  
pp. 2267-2275 ◽  
Author(s):  
Matthew B. Russell ◽  
Aaron R. Weiskittel ◽  
John A. Kershaw
Keyword(s):  
Random Effects ◽  
Mean Squared Error ◽  
Growth Models ◽  
Secondary Growth ◽  
Model Performance ◽  
Basal Area ◽  
Nonlinear Mixed Effects Models ◽  
Absolute Deviation ◽  
Individual Tree

Tree basal area (ba) or diameter at breast height (dbh) are universally used to represent tree secondary growth in individual tree based growth models. However, the long-term implications of using either ba or dbh for predictions are rarely fully assessed. In this analysis, Δba and Δdbh increment equations were fit to identical datasets gathered from six conifer and four hardwood species grown in central Maine. The performance of Δba and Δdbh predictions from nonlinear mixed-effects models were then compared with observed growth measurements of up to 29 years via a Monte Carlo simulation. Two evaluation statistics indicated substantial improvement in forecasting dbh using Δdbh rather than Δba. Root mean squared error (RMSE) and percentage mean absolute deviation (MAD%) were reduced by 14% and 15% on average, respectively, across all projection length intervals (5–29 years) when Δdbh was used over Δba. Differences were especially noted as projection lengths increased. RMSE and MAD% were reduced by 24% when Δdbh was employed over Δba at longer projection lengths (up to 29 years). Simulations found that simulating random effects rather than using local estimates for random effects performed as well or better at longer interval lengths. These results highlight the implications that selecting a growth model dependent variable can have and the importance of incorporating model uncertainty into the growth projections of individual tree based models.

Modelling stand growth of radiata pine thinned to varying densities

1990 ◽  
Vol 20 (7) ◽  
pp. 1069-1076 ◽  
Author(s):  
A. G. D. Whyte ◽  
R. C. Woollons
Keyword(s):  
Negative Selection ◽  
Block Design ◽  
Basal Area ◽  
Radiata Pine ◽  
Projection Model ◽  
Stand Growth ◽  
Thinning Intensity ◽  
Randomized Complete Block Design ◽  
Attainable Yield ◽  
Similar Yield

Growth trends in a radiata pine thinning experiment established 18 years ago in Kaingaroa Forest, New Zealand, are portrayed and analyzed. The six thinnings, to 200, 300, 400, 500, 600, and 700/ha, were carried out at age 7 years; four replicates of each thinning level were laid out in 0.2 ha plots in a randomized complete block design. The dbh outside bark of all trees and the heights of a sample of 12–15 trees per 0.1 ha inner plot were remeasured at least once each year up to age 20 and then at 2-year intervals thereafter. Mean top-height development after age 7 years was little affected by thinning intensity, although initial negative selection may have reduced the subsequent vigour of the most heavily thinned plots. Analysis of a Gompertz projection model for net basal area per hectare and a similar yield formulation indicated that thinning down to 300/ha progressively lowered basal-area production and the maximum attainable yield but did not impair the ability to capture fully the available growing space. The 200/ha treatment, however, was much impaired, and its asymptote was lowered to such an extent that its yield trajectory was continuing to fall away relative to the others. The analysis quantifies this reduction and could possibly allow estimates of how much production would be lost between 200 and 300/ha, so that due allowance could be made when predicting yields for routine thinning prescriptions within that range.

An individual-tree basal area growth model for black spruce in second-growth peatland stands

1999 ◽  
Vol 29 (5) ◽  
pp. 621-629 ◽  
Author(s):  
Hannu Hökkä ◽  
Arthur Groot
Keyword(s):  
Growth Model ◽  
Black Spruce ◽  
Basal Area ◽  
Random Parameter ◽  
Considerable Change ◽  
Tree Level ◽  
Individual Tree ◽  
Basal Area Growth ◽  
Second Growth ◽  
Area Growth

A basal area growth model was developed to predict the growth of individual trees in second-growth black spruce (Picea mariana (Mill.) BSP) stands on northeastern Ontario peatlands. The data were derived from stem analysis trees collected in 1985 and 1986 from stands harvested 47-68 years earlier. For a period starting from the date of data collection and going back to 10 years from the harvesting, tree basal area growth, diameters, and stand characteristics were retrospectively calculated at 5-year intervals. To estimate previous mortality, self-thinning relationships for black spruce were applied. In the model, 5-year basal area growth of a tree was expressed as a function of tree diameter, stand-level competition, tree-level competition, and peat thickness. There was considerable change in the growth-size relationship over time. A random parameter approach was applied in model construction to account for the spatial and temporal correlations of the observations. The proposed model explicitly incorporates factors normally included in a "random error" term and, therefore, should provide more sensitive tests of the contributions of the various factors to growth prediction. The estimated model showed only slight bias against the modeling data and the predicted stand basal area development was comparable with that given in other studies.

A modeling strategy for the growth projection of managed stands

1985 ◽  
Vol 15 (3) ◽  
pp. 511-518 ◽  
Author(s):  
James D. Arney
Keyword(s):  
Data Base ◽  
Large Data ◽  
Height Growth ◽  
Projection Model ◽  
Individual Tree ◽  
Large Data Base ◽  
Tree Distance ◽  
Growth Projection ◽  
Modeling Strategy ◽  
Projection Strategy

Using a large data base of permanent research plots in coastal Douglas-fir, a growth projection strategy is developed. The emphasis is on stratifying growth influences into potential and modifier functions for components of diameter and height growth within a stand table. Growth periods are defined as equal increments of top height through time. The model developed is an individual-tree, distance-independent, stand-projection model.

A new method for evaluating forest thinning: growth dominance in managed Pinus resinosa stands

2010 ◽  
Vol 40 (5) ◽  
pp. 843-849 ◽  
Author(s):  
John B. Bradford ◽  
Anthony W. D’Amato ◽  
Brian J. Palik ◽  
Shawn Fraver
Keyword(s):  
Tree Growth ◽  
Basal Area ◽  
Pinus Resinosa ◽  
Growth Patterns ◽  
Red Pine ◽  
New Method ◽  
Stand Age ◽  
Individual Tree ◽  
Individual Tree Growth

Growth dominance is a relatively new, simple, quantitative metric of within-stand individual tree growth patterns, and is defined as positive when larger trees in the stand display proportionally greater growth than smaller trees, and negative when smaller trees display proportionally greater growth than larger trees. We examined long-term silvicultural experiments in red pine ( Pinus resinosa Ait.) to characterize how stand age, thinning treatments (thinned from above, below, or both), and stocking levels (residual basal area) influence stand-level growth dominance through time. In stands thinned from below or from both above and below, growth dominance was not significantly different from zero at any age or stocking level. Growth dominance in stands thinned from above trended from negative at low stocking levels to positive at high stocking levels and was positive in young stands. Growth dominance in unthinned stands was positive and increased with age. These results suggest that growth dominance provides a useful tool for assessing the efficacy of thinning treatments designed to reduce competition between trees and promote high levels of productivity across a population, particularly among crop trees.

Windthrow following four harvest treatments in an Engelmann spruce - subalpine fir forest in southern interior British Columbia, Canada

1999 ◽  
Vol 29 (10) ◽  
pp. 1547-1556 ◽  
Author(s):  
David J Huggard ◽  
Walt Klenner ◽  
Alan Vyse
Keyword(s):  
Large Scale ◽  
Basal Area ◽  
Random Trees ◽  
Abies Lasiocarpa ◽  
Ecological Processes ◽  
Individual Tree ◽  
Subalpine Fir ◽  
Engelmann Spruce ◽  
Lower Height

We used transect surveys at a large-scale experimental site at Sicamous Creek, B.C., to measure the effects of five treatments on windthrow: 10-ha clearcuts, arrays of 1-ha patch cuts, arrays of 0.1-ha patch cuts, individual-tree selection cuts, and uncut controls. We also examined edge effects and conditions predisposing trees to windthrow. Windthrow of subalpine fir (Abies lasiocarpa (Hook.) Nutt.) in the 2.7 years following harvesting increased from 0.6% of basal area per year in uncut forest to 0.8-1.8% per year in harvested treatments, with highest rates in individual tree selection units and lowest rates in 0.1-ha patch-cut arrays. Engelmann spruce (Picea engelmannii Parry ex Engelm.) showed similar patterns of windthrow but lower rates (0.2-0.7% of basal area per year in harvested treatments). Windthrow was concentrated near north and east edges of 1-ha and 10-ha openings but was dispersed throughout the more uniform treatments. Windthrown trees did not differ from random trees in diameter but had lower height/diameter ratios, probably reflecting the greater windthrow observed in subxeric sites on complex, elevated topography. The rates and distribution of windthrow in different harvest treatments have implications for ecological processes, salvage, long-term windthrow potential, and mitigation possibilities.

Sign in / Sign up

Export Citation Format

Share Document