Effects of species mixtures on growth and stand development of Douglas-fir and red alder

2006 ◽  
Vol 36 (3) ◽  
pp. 768-782 ◽  
Author(s):  
Steven R Radosevich ◽  
David E Hibbs ◽  
Claudio M Ghersa
Keyword(s):  
Pacific Northwest ◽  
Tree Mortality ◽  
Stand Structure ◽  
Stand Density ◽  
Douglas Fir ◽  
Forest Understory ◽  
Red Alder ◽  
Structure Tree ◽  
Species Proportions ◽  
Species Mixtures

In the Pacific Northwest, a mixture of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red alder (Alnus rubra Bong.) often results when red alder regenerates naturally in planted conifer stands. The relationships among stand structure, tree mortality, tree size, and understory development in the two species mixtures were explored at two sites for the first 16 years after planting. Treatments included a range of species proportions, and red alder was either planted simultaneously with Douglas-fir or planting was delayed for 5 years. Red alder was also removed from some simultaneously planted proportions. Both replacement effects (total stand density held constant) and additive effects (stand density doubled) of the interaction were considered. Red alder grew relatively better at Cascade Head Experimental Forest in the Coast Range, while Douglas-fir grew better at H.J. Andrews Experimental Forest in the less temperate Cascade Mountains. Possible production benefits from mixed plantings were examined using two methods of calculation. Potential production benefits from certain planted proportions of the two species occurred at H.J. Andrews Experimental Forest. No planting time or species proportion resulted in yield improvements over monoculture stands at Cascade Head Experimental Forest. Understory species also varied because of differences in site and stand characteristics that resulted from the differences in planting times and species proportions.

Influence of species proportion and timing of establishment on stem quality in mixed red alder – Douglas-fir plantations

2004 ◽  
Vol 34 (4) ◽  
pp. 863-873 ◽  
Author(s):  
Amy T Grotta ◽  
Barbara L Gartner ◽  
Steven R Radosevich
Keyword(s):  
Stand Structure ◽  
Stand Density ◽  
Douglas Fir ◽  
Stem Form ◽  
Mixed Stands ◽  
Red Alder ◽  
Stem Quality ◽  
Multiple Stems ◽  
Old Trees ◽  
Species Proportion

The relationships among stand structure, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) branch characteristics, and red alder (Alnus rubra (Bong.)) stem form attributes were explored for 10- to 15-year-old trees growing in mixed Douglas-fir – red alder plantations. Treatments included a range of species proportions, and red alder was either planted simultaneously with Douglas-fir or after 5 years. Both replacement effects (total stand density held constant) and additive effects (stand density doubled) of competition were considered. When the two species were planted simultaneously and red alder proportion was low, red alder trees had low crown bases and much stem defect (lean, sweep, and multiple stems). Douglas-fir grew slowly when the two species were planted simultaneously. When red alder planting was delayed, species proportion did not affect red alder stem form, and height to the base of the Douglas-fir live crown decreased with increasing red alder proportion. Doubling Douglas-fir density increased the height to the base of the Douglas-fir live crown; however, doubling stand density by adding red alder did not affect Douglas-fir crown height. Douglas-fir lumber coming from mixed stands may be inferior because of the changes in knot characteristics associated with these different patterns of crown recession. In stands with a low proportion of red alder, red alder product recovery may be compromised because of the stem defects described above.

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.

The economics of Douglas-fir and red alder management with stochastic price trends

1993 ◽  
Vol 23 (8) ◽  
pp. 1695-1703 ◽  
Author(s):  
Robert G. Haight
Keyword(s):  
Pacific Northwest ◽  
Financial Analysis ◽  
Probability Distributions ◽  
Low Cost ◽  
The United States ◽  
Douglas Fir ◽  
Mixed Species ◽  
Red Alder ◽  
Commercial Thinning ◽  
Price Trends

A financial analysis of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and red alder (Alnusrubra Bong.) management is conducted using yield projections from the Stand Projection Simulator for the Pacific Northwest region of the United States. The analysis includes uncertainty in the price trends and stocking levels of both species following reforestation. Results from a case study in which Douglas-fir price is likely to increase faster than red alder price show that (i) on more productive sites, greater regeneration investment is justified to increase the likelihood of Douglas-fir establishment; (ii) on less productive sites, low-cost regeneration options that produce mixed-species stands have expected present values close to or greater than a high-cost Douglas-fir regeneration effort; (iii) optimal precommercial removal of red alder depends on midrotation prices and regeneration success, and in many cases growing a mixed-species stand to maturity produces the highest economic return; (iv) commercial thinning of Douglas-fir increases the expected present value of the most intensive regeneration option by up to 10%. The low-cost regeneration options have relatively high expected returns because of low initial investments and the presence of two species that may have high values in the future. The sensitivity of these results to changes in the probability distributions of regeneration success and price trends is discussed.

scholarly journals Predicting postfire Douglas-fir beetle attacks and tree mortality in the northern Rocky Mountains

2007 ◽  
Vol 37 (6) ◽  
pp. 1058-1069 ◽  
Author(s):  
Sharon Hood ◽  
Barbara Bentz
Keyword(s):  
Tree Mortality ◽  
Stand Density ◽  
Douglas Fir ◽  
Dendroctonus Pseudotsugae ◽  
Northern Rocky Mountains ◽  
Crown Volume ◽  
Crown Scorch ◽  
Predicted Probability ◽  
Attack Trees ◽  
Stand Density Index

Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) were monitored for 4 years following three wildfires. Logistic regression analyses were used to develop models predicting the probability of attack by Douglas-fir beetle ( Dendroctonus pseudotsugae Hopkins, 1905) and the probability of Douglas-fir mortality within 4 years following fire. Percent crown volume scorched (crown scorch), cambium injury, diameter at breast height (DBH), and stand density index for Douglas-fir were most important for predicting Douglas-fir beetle attacks. A nonlinear relationship between crown scorch and cambium injury was observed, suggesting that beetles did not preferentially attack trees with both maximum crown scorch and cambium injury, but rather at some intermediate level. Beetles were attracted to trees with high levels of crown scorch, but not cambium injury, 1 and 2 years following fire. Crown scorch, cambium injury, DBH, and presence/absence of beetle attack were the most important variables for predicting postfire Douglas-fir mortality. As DBH increased, the predicted probability of mortality decreased for unattacked trees but increased for attacked trees. Field sampling suggested that ocular estimates of bark char may not be a reliable predictor of cambium injury. Our results emphasize the important role of Douglas-fir beetle in tree mortality patterns following fire, and the models offer improved prediction of Douglas-fir mortality for use in areas with or without Douglas-fir beetle populations.

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.

Stand structure, thinning prescriptions, and density indexes in a Douglas-fir thinning study, Western Washington, U.S.A.

1983 ◽  
Vol 13 (1) ◽  
pp. 126-136 ◽  
Author(s):  
Chadwick Dearing Oliver ◽  
Marshall D. Murray
Keyword(s):  
Stand Structure ◽  
Volume Growth ◽  
Basal Area ◽  
Stand Density ◽  
Close Relation ◽  
Douglas Fir ◽  
Volume Number ◽  
Large Trees ◽  
Before And After ◽  
Number Of Stems

A Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) thinning study was established in 1959 in a stand begun after logging in 1930. Thinnings to set basal area densities were done in 1959, 1962, 1966, and 1970. On each plot both large and small trees were removed since average basal area per tree was kept constant before and after thinning. Volume growth varied greatly between plots of the same age, initial basal area, and site because of differences in stand structure. Large trees on a plot grew more per tree and per basal area than small trees. Stand basal area, stand volume, number of stems, or number of dominant and codominant trees were not closely related to volume growth per hectare, although density indexes giving weight to larger trees showed the closest relation. The lack of close relation between stand density indexes and growth found here and elsewhere probably means the indexes do not uniquely define stand structures; it does not necessarily mean that thinning will not increase volume growth per hectare. Volume growth per hectare after thinning to a given basal area density will be greater and probably more consistent if larger trees are left and enough time is allowed for the stand to recover following thinning.

Size of Douglas-fir trees in relation to distance from a mixed red alder–Douglas-fir stand

1993 ◽  
Vol 23 (11) ◽  
pp. 2413-2418 ◽  
Author(s):  
Richard E. Miller ◽  
Donald L. Reukema ◽  
Timothy A. Max
Keyword(s):  
Stand Density ◽  
Positive Influence ◽  
Poor Quality ◽  
Douglas Fir ◽  
Mixed Stand ◽  
Stem Volume ◽  
Nitrogen Fixing ◽  
Red Alder ◽  
Wide Strip ◽  
Southwest Washington

Variation in diameter, height, and stem volume of 57-year-old Douglas-fir (Pseudotsugamenziesii var. menziesii (Mirb.) Franco) was related to distance of these trees from a 27 m wide strip in the same Douglas-fir plantation that had been interplanted with red alder (Alnusrubra Bong.). Within the interplanted strip and despite its greater total stand density, bole volume of dominant and codominant Douglas-fir averaged 1.27 m3 compared with 0.55, 0.45, 0.46, or 0.49 m3 in trees 15, 30,45, or 60 m, respectively, from the edge of the mixed stand. Some positive influence of nitrogen-fixing red alder apparently extended about 15 m beyond the edge of the mixed stand at this poor quality site in southwest Washington. We infer that similar ribbonlike distributions of naturally regenerated red alder could be retained to improve growth of nearby conifers on nitrogen-deficient sites.

Stand structure and growing space efficiency following thinning in an even-aged Douglas-fir stand

1988 ◽  
Vol 18 (7) ◽  
pp. 859-866 ◽  
Author(s):  
K. L. O'Hara
Keyword(s):  
Stand Structure ◽  
Volume Growth ◽  
Basal Area ◽  
Stand Density ◽  
Douglas Fir ◽  
Stem Volume ◽  
Projection Area ◽  
Individual Tree ◽  
Space Efficiency ◽  
Individual Trees

The growth of individual trees from four thinning treatments in a 64-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand was analyzed to determine desirable residual stand structures after thinning. Dominant and codominant trees had the highest individual tree stem volume growth rates over the previous 5 years, and accounted for most stand volume growth in thinned and unthinned stands. Two measures of growing space, crown projection area and sapwood basal area (a surrogate for leaf area), were used to measure how efficiently individual trees used their growing space. Crown classes were useful in characterizing growing space efficiency (volume growth per unit of growing space) only in the unthinned treatment. In thinned treatments, tall trees with medium-sized crowns were most efficient, while in the unthinned treatment, tall trees with relatively large crowns were most efficient. A large crown in an unthinned stand was comparable in size to a medium-sized crown in a thinned stand. Results suggest growing space is not limiting individual tree growth in thinned stands and that thinning to a particular stand structure is more appropriate than thinning to a particular level of stand density.

scholarly journals The Effects of Tree and Stand Traits on the Specific Leaf Area in Managed Scots Pine Forests of Different Ages

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 396
Author(s):  
Agnieszka Błasiak ◽  
Andrzej Węgiel ◽  
Adrian Łukowski ◽  
Sławomir Sułkowski ◽  
Mieczysław Turski
Keyword(s):  
Leaf Area ◽  
Scots Pine ◽  
Specific Leaf Area ◽  
Stand Structure ◽  
Light Exposure ◽  
Direct Method ◽  
Stand Density ◽  
Tree Age ◽  
Structure Tree ◽  
Northwestern Poland

The purpose of this study was to understand the relationships between stand structure (tree size, volume, biomass, social position, stand density) and the variability of specific leaf area (SLA) at the stand level, which could improve forest management modeling. The study was carried out on 100 trees selected from 10 stands of Scots pine located in northwestern Poland. The stands had been established in a similar way and were similarly managed. Five mid-aged (51–60 years) and five mature (81–90 years) pure Scots pine stands were selected. To obtain the SLA index, we used the direct method, which involves scanning ca. 50 needles from each part of the tree crown. The average SLA was from 4.65 to 6.62 m2·kg−1 and differed significantly according to the part of the crown measured (p < 0.0001) and the tree age (p < 0.0001). The smallest SLA was in the upper part of the crown and the largest in the lower part of the crown, which is in line with the known relation to the light exposure of needles. Mid-aged stands of Scots pine have higher SLA values than mature ones. Dominant trees in mid-aged stands have a lower SLA than more shaded intermediate ones, which is probably due to the different lighting conditions within the canopy. No clear relationship is observed between the stand density and the SLA.

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