scholarly journals The role of epicormic shoot production in maintaining foliage in old Pseudotsuga menziesii (Douglas-fir) trees II. Basal reiteration from older branch axes

2002 ◽  
Vol 80 (9) ◽  
pp. 916-926 ◽  
Author(s):  
Hiroaki Ishii ◽  
E David Ford ◽  
C Elaine Dinnie
Keyword(s):  
Pseudotsuga Menziesii ◽  
Growth Ring ◽  
Maximum Size ◽  
Douglas Fir ◽  
Branch Growth ◽  
Constant Rate ◽  
Shoot Production ◽  
Wide Range ◽  
Epicormic Shoot ◽  
Ring Analysis

Basal reiteration (epicormic shoot production from older branch axes) occurred continuously and repeatedly in branches of 450-year-old Pseudotsuga menziesii (Mirb.) Franco var. menziesii (coastal Douglas-fir) trees reproducing sections of branches comprising less than 100 to as many as 10 000 foliated shoots. Basal reiteration occurred mostly from primary and secondary branch axes but also occurred from higher-order axes if lower-order axes had died back. Basal reiteration occurred in distal sections of upper-crown branches, while it occurred in more proximal sections of middle- and lower-crown branches, indicating that basal reiteration works to distribute foliage more uniformly within branches that have reached maximum size. Basal reiteration occurred repeatedly producing two to six generations of reiterated axes within branches. Less than 22.5% of foliated shoots on branches were produced by sequential branching of the primary axis. Basal reiteration also maintained a constant rate of new shoot production within the branch. Growth-ring analysis showed that basal reiteration occurred over a wide range of axis ages (5–58 years). In conjunction with previous studies, we showed that adaptive reiteration of various architectural units by epicormic shoot production is an inherent process that maintains foliage in the crown of old P. menziesii trees.Key words: branch growth, branching pattern, crown maintenance, longevity.

scholarly journals The role of epicormic shoot production in maintaining foliage in old Pseudotsuga menziesii (Douglas-fir) trees

2001 ◽  
Vol 79 (3) ◽  
pp. 251-264 ◽  
Author(s):  
Hiroaki Ishii ◽  
E David Ford
Keyword(s):  
Pseudotsuga Menziesii ◽  
Maximum Size ◽  
Douglas Fir ◽  
Epicormic Shoots ◽  
Relative Age ◽  
Shoot Production ◽  
Epicormic Shoot ◽  
Five Phases ◽  
Architectural Unit

Shoots and foliage on branches of old Pseudotsuga menziesii (Mirb.) Franco var. menziesii (coastal Douglas-fir) trees are constantly renewed by epicormic shoot production. Epicormic shoots are produced in all parts of the crown, and epicormic buds remain dormant for 5 or 6 years on average. Epicormic shoot production results in reiteration of shoot cluster units (SCUs), an architectural unit of shoot organization within branches. Five phases of SCU development were identified based on relative age structures of regular and epicormic shoots. SCUs produce epicormic branchlets as early as 3 or 4 years of age, and peak production occurred around 6-13 years. Epicormic branchlets occur toward the proximal end of main axes of SCUs, where regular lateral branchlets are no longer producing new shoots. In some lower-crown branches, nearly 50% of shoots and foliage are epicormic shoots. Demographic analysis of SCUs showed that upper-crown branches are still growing in size, while mid- and lower-crown branches have reached maximum size, and are being maintained by reiteration of SCUs. Epicormic shoot production maintains shoots and foliage of old P. menziesii trees after height growth and crown expansion have stopped and may contribute to prolonging tree longevity.Key words: aging, branch growth, epicormic shoots, longevity, Pseudotsuga menziesii, reiteration.

scholarly journals Adjacency to a harvest trail increases drought resistance of interior Douglas-fir (Pseudotsuga menziesii var. glauca) in partially harvested stands in central British Columbia

2018 ◽  
Vol 48 (7) ◽  
pp. 809-820 ◽  
Author(s):  
Neil P. Thompson ◽  
Kathy J. Lewis ◽  
Lisa M. Poirier
Keyword(s):  
British Columbia ◽  
Drought Tolerance ◽  
Pseudotsuga Menziesii ◽  
Growth Rates ◽  
Habitat Management ◽  
Odocoileus Hemionus ◽  
Douglas Fir ◽  
Ring Analysis ◽  
The Relationship

Drought tolerance of trees may be affected by competition, but most studies quantifying the relationship do not consider the effect of stem clustering. Trees are often clustered in interior Douglas-fir (Pseudotsuga menziesii var. glauca (Mayr) Franco) forests near the grassland interface in central British Columbia due to past harvesting practices or habitat management for mule deer (Odocoileus hemionus hemionus (Rafinesque, 1817)). Climate change projections indicate continued increases in temperature, an outcome that would stress trees growing in dry environments. Trees placed in different states of competition by mechanical harvesting in the 1970s were sampled to provide a 40-year comparison of three levels of competition during 1–2 year droughts. Tree-ring analysis was used to assess the reduction in growth during drought years and resumption of growth in subsequent years. A clear separation of growth rates was evident between open-growing trees, trees on the edge of harvesting trails, and trees within the unharvested interior. Edge trees had intermediate growth rates but no differences were found in the long-term climate–growth relationship compared with open-growing trees. Both Edge and Open classes showed less relative growth reduction during droughts than Interior trees growing between harvest trails. Precipitation throughfall rates and competition for resources are likely driving short-term drought tolerance in combination with other factors.

scholarly journals Effects of live crown on vertical patterns of wood density and growth in Douglas-fir

2002 ◽  
Vol 32 (3) ◽  
pp. 439-447 ◽  
Author(s):  
Barbara L Gartner ◽  
Eric M North ◽  
G R Johnson ◽  
Ryan Singleton
Keyword(s):  
Wood Density ◽  
Juvenile Wood ◽  
Growth Ring ◽  
Ring Width ◽  
Douglas Fir ◽  
Mature Wood ◽  
Node Number ◽  
Growth Ring Width ◽  
Residual Variation ◽  
Wide Range

It would be valuable economically to know what are the biological triggers for formation of mature wood (currently of high value) and (or) what maintains production of juvenile wood (currently of low value), to develop silvicultural regimes that control the relative production of the two types of wood. Foresters commonly assume the bole of softwoods produces juvenile wood within the crown and mature wood below. We tested that assumption by comparing growth ring areas and widths and wood density components of the outer three growth rings in disks sampled from different vertical positions of 34-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. The 18 trees were sampled from one site and had a wide range of heights to live crown. Most of the variance (63–93%) in wood characteristics (growth ring area: total, earlywood, latewood; growth ring width: total, earlywood, latewood; latewood proportion: by area, width; and ring density: total, earlywood, latewood) was due to within-tree differences (related to age of the disk). Stepwise regression analysis gave us equations to estimate wood characteristics, after which we analyzed the residuals with a linear model that included whether a disk was within or below the crown (defined as the lowest node on the stem with less than three live branches). After adjusting for tree and disk position, only 2–10% of the residual variation was associated with whether the disk was in or out of the live crown. There were no statistically significant differences at p = 0.05 between a given disk (by node number) in versus out of the crown for any of the factors studied. Moreover, the wood density characteristics were not statistically significant at p = 0.30. This research suggests that there was no effect of the crown position on the transition from juvenile to mature wood as judged by wood density. Therefore, we found no evidence to support the concept that tree spacing and live-branch pruning have a significant effect on the cambial age of transition from juvenile to mature wood in Douglas-fir trees of this age.

scholarly journals Variation in specific needle area of old-growth Douglas-fir in relation to needle age, within-crown position and epicormic shoot production

2002 ◽  
Vol 22 (1) ◽  
pp. 31-40 ◽  
Author(s):  
H. Ishii ◽  
E. D. Ford ◽  
M. E. Boscolo ◽  
A. C. Manriquez ◽  
M. E. Wilson ◽  
...  
Keyword(s):  
Douglas Fir ◽  
Old Growth ◽  
Needle Age ◽  
Crown Position ◽  
Shoot Production ◽  
Epicormic Shoot

Tracheid Length in Vital and Non Vital Douglas Fir (Pseudotsuga Menziesii) in the Netherlands

IAWA Journal ◽  
1990 ◽  
Vol 11 (2) ◽  
pp. 203-209 ◽  
Author(s):  
Ingrid de Kort
Keyword(s):  
The Netherlands ◽  
Pseudotsuga Menziesii ◽  
Growth Ring ◽  
Ring Width ◽  
Douglas Fir ◽  
Growth Reduction ◽  
Tracheid Length ◽  
Growth Ring Width ◽  
Temporary Growth

Tracheid length in relation to growth ring width is recorded for five Douglas firs from different sites in the Netherlands. The investigated trees differed in vitality assessed by crown appearance. Non vital trees showed a growth reduction which coincides with a decrease in tracheid length. Temporary growth reductions in vital trees did not result in a decrease of tracheid length. The relations hip between tracheid length and ring width is discussed.

scholarly journals Growth of Residual Branches on Pruned Coastal Douglas-Fir

2003 ◽  
Vol 18 (3) ◽  
pp. 185-188 ◽  
Author(s):  
Eric C. Turnblom ◽  
Randol L. Collier
Keyword(s):  
Pseudotsuga Menziesii ◽  
Branch Length ◽  
Douglas Fir ◽  
Anecdotal Evidence ◽  
Modest Increase ◽  
Branch Growth ◽  
Real Risk ◽  
Branch Size

Abstract Anecdotal evidence gathered from pruning crew observations indicates that there may be enhanced branch growth at the new crown base in young pruned coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) trees compared to unpruned trees. This has the potential to reduce the quality and value of the stem above the pruned portion of the bole. An analysis of the size of branches in the remaining crown on pruned trees and matched unpruned trees of the same size at the time of pruning indicates that residual branches do not increase in diameter or length in response to light and moderate pruning. However, with a severe pruning there was a modest increase in branch length. Residual branch size in response to pruning 4 yr after treatment appears to offer no real risk in degrading quality of the unpruned portion of the stem as a cost for increasing the quality of the pruned stem. West. J. Appl. For. 18(3):185–188.

A method for estimating vulnerability of Douglas-fir growth to climate change in the northwestern U.S.

2005 ◽  
Vol 81 (3) ◽  
pp. 369-374 ◽  
Author(s):  
Jeremy S Littell ◽  
David L Peterson
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
Pseudotsuga Menziesii ◽  
Douglas Fir ◽  
Climate Impacts ◽  
Spatiotemporal Variability ◽  
Limiting Factors ◽  
Montane Forests ◽  
Growth Variability ◽  
Wide Range

Borrowing from landscape ecology, atmospheric science, and integrated assessment, we aim to understand the complex interactions that determine productivity in montane forests and utilize such relationships to forecast montane forest vulnerability under global climate change. Specifically, we identify relationships for precipitation and temperature that govern the spatiotemporal variability in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) growth by seeking similarities in patterns of growth/climate models across a significant portion of the climatological range of the species. In the 21st century and beyond, sustainable forestry will depend on successful adaptation to the impacts of climate change and climate variability on forest structure and function. The combination of these foci will allow improved prediction of the fate of montane forests over a wide range of biogeoclimatic conditions in western North America and thus allow improved management strategies for adapting to climate change. We describe a multi-disciplinary strategy for analyzing growth variability as a function of climate over a broad range of local-to-regional influences and demonstrate the efficacy of this sampling method in defining regional gradients of growth-limiting factors. Key words: Douglas-fir, Pseudotsuga menziesii, climate variability, climate impacts, mechanism-response, tree rings, growth-climate relationships

Physiologically derived predictions of Douglas-fir site index in British Columbia

2009 ◽  
Vol 85 (5) ◽  
pp. 733-744 ◽  
Author(s):  
Nicholas C Coops ◽  
Robbie A Hember
Keyword(s):  
British Columbia ◽  
Soil Water ◽  
Pseudotsuga Menziesii ◽  
Tree Height ◽  
Site Index ◽  
Douglas Fir ◽  
Forest Growth ◽  
Individual Tree ◽  
Forest Growth Model ◽  
Wide Range

Both the coastal and interior varieties of Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco; Pseudotsuga menziesii var. glauca) are found throughout a wide range of environmental conditions across British Columbia. The species is long-lived and can grow rapidly to standing volumes that approach the highest recorded among temperate conifers. Understanding the growth of the species across British Columbia, and its site index (defined as individual tree height at 50 m) is important for forest managers for both production and conservation objectives. To date, predictions of site index have traditionally been derived from forest inventory using estimates of species, height and age combined with the appropriate height–age model. More recently, process-based modelling has offered a viable alternative approach due to increased computing power, model simplifications and availability of input data. In this paper we applied a physiological forest growth model, 3-PG (Physiological Principles Predicting Growth) to predict and map site index of Douglas-fir across British Columbia at 1-km cell resolution. Our model predictions were scaled-up and compared to independent estimates of average site index for subzones from the British Columbia Biogeoclimatic Ecosystem Classification (BEC) system. Results indicated the 3-PG predictions closely matched those summarized by the BEC sub-zones (r = 0.86, p<0.001, SE = 3.0m). Predicted environmental limitations of growth suggest that the coastal variety of the species is most severely affected by temperature and frost constraints, and in some locations, soil water stress, whereas the interior variety is principally restricted by soil water availability. The proposed modelling approach complements ecological classifications and offers the potential to identify the most favourable sites for management of other native tree species under current and projected climates. Key words: Douglas-fir, site index, physiological modelling, 3-PG model, forest productivity, British Columbia, Canada

Seasonal changes in the water balance of Douglas-fir (Pseudotsuga menziesii) seedlings grown under different light intensities

1979 ◽  
Vol 57 (6) ◽  
pp. 666-674 ◽  
Author(s):  
Allan P. Drew ◽  
William K. Ferrell
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Pseudotsuga Menziesii ◽  
Douglas Fir ◽  
Leaf Conductance ◽  
Soil Drought ◽  
Plant Water ◽  
Wide Range ◽  
Plant Water Potential ◽  
Lower Plant

The water relations of germinant seedlings of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) grown outdoors under 9, 44, and 100% full light were analyzed during the summer, autumn, and winter seasons. Empirical regression models, based on the relationship plant water potential = f(soil water potential, leaf conductance), were determined for selected light treatment – season combinations. Plant water potential is higher during active summer shoot growth than after elongation growth has ceased in the autumn owing to earlier stomatal closure in response to soil drought in summer compared with a more abrupt closure at a lower plant water potential in the autumn.For all light treatments, leaf conductance declined in the winter independent of plant water potential and simultaneously with the onset of subfreezing air temperatures. During the first winter, water potential of seedlings was higher than during the previous summer or autumn over a wide range of equivalent soil water potentials.Seedlings grown under low light intensity are less drought resistant and have lower plant water potential than those grown under full light regardless of soil moisture status.

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