Growth and yield of all-aged Douglas-fir – western hemlock forest stands: a matrix model with stand diversity effects

2005 ◽  
Vol 35 (10) ◽  
pp. 2368-2381 ◽  
Author(s):  
Jingjing Liang ◽  
Joseph Buongiorno ◽  
Robert A Monserud
Keyword(s):  
Species Diversity ◽  
Matrix Model ◽  
The United States ◽  
Douglas Fir ◽  
Growth And Yield ◽  
Western Hemlock ◽  
Permanent Plots ◽  
Forest Stands ◽  
Individual Tree ◽  
Size Diversity

A density-dependent matrix model was developed for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) – western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest stands in the Pacific Northwest of the United States. The model predicted the number and volume of trees for 4 species groups and 19 diameter classes. The parameters were based on species-dependent equations linking individual tree growth, mortality, and stand recruitment to tree and stand characteristics, including stand diversity in terms of tree species and size. The equations were estimated with individual tree and stand data from 2706 permanent plots in western Washington and Oregon, largely from private and state lands, measured twice at an average interval of 10 years. Other things being equal, diameter growth increased slightly with species diversity and decreased with size diversity. Recruitment increased with species diversity and decreased with size diversity. Mortality was independent of species diversity and tended to increase with size diversity. There was practically no relationship between individual tree volume and species or size diversity. The number of trees predicted by the model over the interval between successive inventories was generally unbiased. Long-term predictions with different initial conditions were consistent with standard yield tables and compared favorably with those of the Forest Vegetation Simulator. The model also implied that, independently of its initial condition, an undisturbed stand would eventually reach a steady state dominated by western hemlock more than 1 m in diameter, with few trees of other species and size.

Evaluating the influence of stem form and damage on individual-tree diameter increment and survival in the Acadian Region: implications for predicting future value of northern commercial hardwood stands

2018 ◽  
Vol 48 (9) ◽  
pp. 1007-1019 ◽  
Author(s):  
Mark Castle ◽  
Aaron Weiskittel ◽  
Robert Wagner ◽  
Mark Ducey ◽  
Jereme Frank ◽  
...  
Keyword(s):  
Growth And Yield ◽  
Tree Level ◽  
Permanent Plots ◽  
Stem Form ◽  
Individual Tree ◽  
Tree Diameter ◽  
Diameter Increment ◽  
Hardwood Species ◽  
Future Value

Northern hardwood species display a variety of forms and defects that can reduce stem quality and complicate their timber management. However, for the most part, growth and yield models do not account for the influence of stem form and damage. This study determined the influence of stem form and damage on growth, survival, and projected future sawlog value among several northern commercial hardwood species. To accomplish this, hardwood trees on 112 permanent plots across three long-term research sites in Maine were assigned stem form and risk classes using a tree classification system developed in New Brunswick. A highly significant influence of stem form and risk on annualized individual-tree diameter increment and survival was found. Inclusion of these equations into a regional growth and yield model highlighted the importance of stem form and defects on long-term simulations as projected stand-level future value was significantly reduced by over 17%, on average (range of 13% to 28%), when compared with projections that did not include that tree-level information. The results highlight the importance of stem form and defects, as well as the need to account for them, in growth and yield applications that assess the forecasted value of commercially important hardwood stands.

Comparing productivity of pure and mixed Douglas-fir and western hemlock plantations in the Pacific Northwest

2006 ◽  
Vol 36 (6) ◽  
pp. 1484-1496 ◽  
Author(s):  
M M Amoroso ◽  
E C Turnblom
Keyword(s):  
Pacific Northwest ◽  
Stand Density ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Mixed Stand ◽  
Mixed Stands ◽  
Individual Tree ◽  
The Pacific ◽  
Increase In Productivity

We studied pure and 50/50 mixtures of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) plantations to compare attained total yields between mixed-species stands as opposed to monocultures of equal densities. Whether overall stand density influences this outcome has not been adequately investigated, and to address this we included three density levels (494, 1111, and 1729 trees/ha) in the analysis. At age 12, as components of the mixed stands, Douglas-fir exhibited greater height, diameter, and individual-tree volume than western hemlock at all densities. At 494 and 1111 trees/ha the monocultures had a higher volume per hectare than the mixed stand, but at 1729 trees/ha the mixed stand appeared to be just as productive as the pure stands. The increase in productivity by the mixture at high densities seems to have resulted from the partial stratification observed and most likely also from better use of the site resources. Because of this, less interspecific competition was probably experienced in the mixed stand than intraspecific competition in the pure stands. This study shows the important role density plays in the productivity of mixed stands and thus in comparing mixed and pure stands.

Effects of thinning-induced changes in structural heterogeneity on growth, ingrowth, and mortality in secondary coastal Douglas-fir forests

2015 ◽  
Vol 45 (11) ◽  
pp. 1448-1461 ◽  
Author(s):  
Christian Kuehne ◽  
Aaron R. Weiskittel ◽  
Shawn Fraver ◽  
Klaus J. Puettmann
Keyword(s):  
Species Diversity ◽  
Prediction Models ◽  
Structural Diversity ◽  
Structural Heterogeneity ◽  
Variable Density ◽  
Douglas Fir ◽  
Tree Level ◽  
Spatially Explicit ◽  
Individual Tree ◽  
Diversity Measures

Thinning is believed to accelerate the development of late-successional attributes, thereby enhancing stand structural heterogeneity in young, secondary forests. By making use of a large-scale experiment implemented in 40- to 60-year-old coastal Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) forests, we addressed the following objectives: (i) determine the effect of three thinning treatments on the temporal dynamics (first 11 years after thinning) of key forest structure measures, (ii) evaluate the relationships between spatially explicit structural diversity measures and spatially nonexplicit stand metrics, and (iii) test the relationships between stand structure and observed periodic stand volume growth, ingrowth, and mortality. Treatments consisted of high-density, moderate-density, and variable-density thinnings-from-below, as well as a control. Differences in stand structural heterogeneity between treatments were mostly nonsignificant. However, our results suggest that variable-density stands displayed structural enrichment as tree size and tree species diversity increased throughout the study period as a result of continuous ingrowth of species other than Douglas-fir. Simple spatially nonexplicit metrics could not be used to reliably model spatially explicit structural diversity measures. The inclusion of structural and species diversity measures only rarely improved accuracy of sample plot level growth, ingrowth, and mortality prediction models. Despite the short-term nature of this study, we conclude that variable-density thinning shows promise in increasing structural heterogeneity in young even-aged stands. The inclusion of structural diversity measures in growth and mortality models may be beneficial, but further work is needed to clarify the underlying relationships, particularly at the individual-tree level.

Tree growth at stand and individual scales in two dual-species mixture experiments in southern Washington State, USA

2009 ◽  
Vol 39 (6) ◽  
pp. 1119-1132 ◽  
Author(s):  
Heather E. Erickson ◽  
Constance A. Harrington ◽  
David D. Marshall
Keyword(s):  
Tree Growth ◽  
Tree Species ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Pinus Monticola ◽  
White Pine ◽  
Species Identity ◽  
Individual Tree ◽  
Western White Pine ◽  
Competition For Light

Planting with mixtures of tree species rather than single species is often considered during reforestation because of the potential increased productivity and other benefits. We examined tree growth at the stand and individual tree scales in two experiments contrasting monocultures with a 1:1 mixture of tree species: (1) Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) with a conifer of similar shade tolerance (western white pine ( Pinus monticola Dougl. ex D. Don)) and (2) Douglas-fir with a more shade-tolerant conifer (western hemlock ( Tsuga heterophylla (Raf.) Sarg.)). There was no effect of mixture on growth or yield in the Douglas-fir – western white pine combination. In the Douglas-fir – western hemlock combination, yields in the mixture equaled those in Douglas-fir stands because of the enhanced performance of Douglas-fir in the mixture. For Douglas-fir, the height/diameter (h/d) ratio was significantly less in mixture, suggesting reduced competition for light when grown with western hemlock. In contrast, the h/d ratio for western hemlock was significantly greater in mixture, suggesting increased competition for light when grown with Douglas-fir. Neighborhood analyses showed that tree growth was directly related to initial size and inversely related to relative neighbor size and that the h/d ratio was positively related to relative neighbor size. In general, the size of a neighboring tree influenced growth more than species identity. Relationships between h/d ratios and growth rates suggest that growth differences between Douglas-fir and western hemlock in mixture will eventually increase.

scholarly journals The SOHARC Model System for Growth and Yield of Southern Hardwoods

2008 ◽  
Vol 32 (4) ◽  
pp. 173-183 ◽  
Author(s):  
John Paul McTague ◽  
David O'Loughlin ◽  
Joseph P. Roise ◽  
Daniel J. Robison ◽  
Robert C. Kellison
Keyword(s):  
Tree Growth ◽  
Growth Models ◽  
Basal Area ◽  
Tree Height ◽  
Growth And Yield ◽  
Permanent Plots ◽  
Red Maple ◽  
Yellow Poplar ◽  
Individual Tree ◽  
Individual Tree Growth

Abstract A system of stand level and individual tree growth-and-yield models are presented for southern hardwoods. These models were developed from numerous permanent growth-and-yield plots established across 13 states in the US South on 9 site types, in even-aged (age classes from 20 to 60 years), fully stocked, naturally regenerated mixed hardwood and mixed hardwood-pine stands. Nested plots (⅕ and ac) were remeasured at 5-year intervals. The system of permanent plots was established and maintained by private and public members in the North Carolina State University Hardwood Research Cooperative. Stand level models are presented for dominant height, survival, basal area prediction and projection, and the ingrowth component. Individual tree diameter growth and tree height models were constructed for the most common species: sweetgum, tupelo, yellow-poplar, blackgum, and red maple. All other species were grouped according to growth dynamics into four species groups using cluster analysis. A ranking variable was incorporated into the individual tree growth models to account for competition.

Financial Analysis of Pruning Douglas-Fir and Ponderosa Pine in the Pacific Northwest

1993 ◽  
Vol 8 (2) ◽  
pp. 58-61 ◽  
Author(s):  
Roger D. Fight ◽  
Natalie A. Bolon ◽  
James M. Cahill
Keyword(s):  
Interest Rates ◽  
Ponderosa Pine ◽  
Douglas Fir ◽  
Growth And Yield ◽  
Rate Of Return ◽  
Internal Rate Of Return ◽  
Financial Return ◽  
Individual Tree ◽  
Internal Rate ◽  
The Cost

Abstract Recent lumber recovery studies of pruned and unpruned Douglas-fir (Pseudotsuga menziesii var. menziesii) and ponderosa pine (Pinus ponderosa var. ponderosa) were incorporated into computer software using lumber grade prices, growth and yield data, the cost of pruning, and interest rates to determine the expected financial return from pruning. Financial analyses showed that the cost of pruning at which the investment would yield an expected 4% real rate of return was positive on sites where individual tree growth is fairly high, pruning is done as early as biologically possible given limitations on crown removal, and the harvest is 30 to 70 yr after pruning. The better situations in Douglas-fir showed a breakeven cost of up to $21/tree and an internal rate of return exceeding 9%. The better situations in ponderosa pine showed a breakeven cost of up to $11/tree and an internal rate of return of 7%. West. J. Appl. For. 10(1):58-61.

Modeling mortality in mixed-species stands of coastal British Columbia

2010 ◽  
Vol 40 (8) ◽  
pp. 1517-1528 ◽  
Author(s):  
Leah C. Rathbun ◽  
Valerie LeMay ◽  
Nick Smith
Keyword(s):  
British Columbia ◽  
Basal Area ◽  
Stochastic Approach ◽  
Tsuga Heterophylla ◽  
Growth And Yield ◽  
Estimation Accuracy ◽  
Thuja Plicata ◽  
Permanent Plots ◽  
Yield Model ◽  
Individual Tree

Individual-tree distance-independent models were developed to estimate regular mortality for western hemlock ( Tsuga heterophylla (Raf.) Sarg.), Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. menziesii), and western redcedar ( Thuja plicata Donn ex D. Don) in the coastal temperate rain forests of British Columbia, Canada. Permanent plots remeasured at intervals ranging from 1 to 17 years were used. Because of the irregular remeasurement intervals, survival was estimated using a generalized logistic model and mortality was calculated by subtraction. Basal area of trees larger than the subject tree provided reasonably accurate mortality estimates for larger trees. However, poor results were obtained for trees less than 7.5 cm in diameter at breast height, which had higher mortality rates than the larger trees. Since the implementation of a survival (or mortality) model within a growth and yield model environment can largely affect estimation accuracy, three methods of implementing the model were also evaluated. A probability multiplier approach where the stems per hectare surviving to the next period is estimated by multiplying the probability of survival by the stems per hectare at the beginning of the time period is recommended. This is equivalent to a stochastic approach averaged over many repetitions but with much less processing time.

scholarly journals Effects of natural broadleaved regeneration vs conifer restoration on the herb layer and microclimate

2016 ◽  
Vol 68 (3) ◽  
pp. 483-493
Author(s):  
Dragana Vukov ◽  
Zoran Galic ◽  
Marko Rucando ◽  
Milos Ilic ◽  
Mirjana Cuk ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Correspondence Analysis ◽  
Detrended Correspondence Analysis ◽  
Beech Forest ◽  
Douglas Fir ◽  
Pteridium Aquilinum ◽  
Permanent Plots ◽  
Herb Layer ◽  
Forest Stands ◽  
Floristic Similarity

This study was carried out on the Vidlic Mountain, eastern Serbia. The herb layer was surveyed in permanent plots on two localities: in a naturally regenerated beech forest and in a Douglas-fir plantation, in spring, summer and autumn 2011, 2012 and 2013. Air temperature, air humidity and soil moisture were measured. Species richness, Shannon?s diversity index and Pielou?s evenness index were calculated for each plot. Comparison of the abundances of species common to both forest stands was done using the Mann-Whitney U-test. The compositional gradient of the species data was examined using detrended correspondence analysis (DCA), and the species-environment relationship was analyzed by canonical correspondence analysis (CCA). Soil moisture and the total herb cover significantly differed in the naturally regenerated beech forest and Douglas-fir plantation. Floristic similarity between the surveyed forest stands was 28.12%. Although the dominant canopy species is known to be the strongest predictor of the herb layer, the model that includes all of the analyzed environmental factors explains the largest amount of the species variability. The species best fitted to this model are Dryopteris filix-mas, Galium odoratum, Pulmonaria officinalis, Sanicula europaea, Pteridium aquilinum and Rubus caesius. The analyzed forest stands are examples of two different post-disturbance regeneration strategies. Having in mind the limitations of this study, we can conclude that the naturally regenerated beech forest recovers faster: its herbaceous layer indicated nearly natural conditions, with only a few pioneer and disturbance-tolerant species. The herb layer in the Douglas-fir stand is still in the early seral stage, i.e. establishment.

Canopy gaps in Douglas-fir forests of the Cascade Mountains

1990 ◽  
Vol 20 (5) ◽  
pp. 649-658 ◽  
Author(s):  
Thomas A. Spies ◽  
Jerry F. Franklin ◽  
Mark Klopsch
Keyword(s):  
Canopy Structure ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Permanent Plots ◽  
Gap Size ◽  
Gap Formation ◽  
Seedling Density ◽  
Old Growth ◽  
Mature Stand ◽  
Mature Stands

Types and rates of mortality were measured and canopy gap formation rates were estimated from 5- to 15-year records of mortality in 34 permanent plots in mature (100- to 150-year-old) and old-growth (>200-year-old) Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco)/western hemlock (Tsugacanadensis (Raf.) Sarg.) forests in western Oregon and Washington. Gap surveys were conducted in a mature and an old-growth stand, and characteristics of 40 gaps and regeneration were measured. Most canopy trees died without disrupting the forest in both mature (87.6%) and old-growth stands (73.3%). The amount of forest area per year representing new gaps was 0.7% in mature stands and 0.2% in old-growth stands. The gap survey found a higher proportion of gaps in the mature stand than in the old-growth stand. Most regeneration (> 1 m tall) in gaps was western hemlock; Douglas-fir regeneration did not occur. The ratio of seedling density in gaps to density under canopies was about 3 for the mature stand and about 9 for the old-growth stand. Seedling density was correlated with measures of gap age but not gap size. The study suggests that gap disturbances and vegetative responses are important processes in the dynamics of these forests. However, gap formation rates and vegetative responses appear to be slow relative to other forest types. In addition to gap size, canopy structure and disturbance severity are important determinants of gap response.

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