The genus Rhabdocline Syd.

1969 ◽  
Vol 47 (10) ◽  
pp. 1533-1545 ◽  
Author(s):  
A. K. Parker ◽  
James Reid
Keyword(s):  
Pseudotsuga Menziesii ◽  
Douglas Fir ◽  
Disease Symptoms ◽  
Needle Cast ◽  
Imperfect Fungus ◽  
Thin Walled ◽  
Relationship Of ◽  
The Relationship ◽  
Iodine Reaction

The various entities included under the name Rhabdocline pseudotsugae Syd., the fungus causing a needle cast of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), have been placed into two species primarily on the basis of differences in structure of their ascus apices. The ascospores of Rhabdocline pseudotsugae (which includes R. pseudotsugae subsp. pseudotsugae and R. pseudotsugae subsp. epiphylla subsp. nov.) are ejected through variously ruptured thin-walled ascus apices, while ascospores of Rhabdocline weirii sp. nov. (which includes R. weirii subsp. weirii, R. weirii subsp. oblonga subsp. nov., and R. weirii subsp. obovata subsp. nov.) are ejected through distinct annular pores. An emendment to the diagnosis of Rhabdocline has been made. R. weirii subsp. weirii was the only entity found to be associated with the imperfect fungus Rhabdogloeum pseudotsugae Syd. The relationship of Rhabdocline to other members of the Hemiphacidiaceae, the significance of the constancy of the fungus and disease symptoms in Europe, the iodine reaction of asci, and spore maturity are discussed.

scholarly journals Predicting Swiss Needle Cast Disease Distribution and Severity in Young Douglas-Fir Plantations in Coastal Oregon

2003 ◽  
Vol 93 (7) ◽  
pp. 790-798 ◽  
Author(s):  
Pablo H. Rosso ◽  
Everett M. Hansen
Keyword(s):  
Prediction Model ◽  
Disease Severity ◽  
Pacific Northwest ◽  
Regression Tree ◽  
Douglas Fir ◽  
Slope Aspect ◽  
Disease Prediction ◽  
Needle Cast ◽  
Swiss Needle Cast ◽  
The Relationship

Swiss needle cast (SNC), caused by the fungus Phaeocryptopus gaeumannii, is producing extensive defoliation and growth reduction in Douglas-fir forest plantations along the Pacific Northwest coast. An SNC disease prediction model for the coastal area of Oregon was built by establishing the relationship between the distribution of disease and the environment. A ground-based disease survey (220 plots) was used to study this relationship. Two types of regression approaches, multiple linear regression and regression tree, were used to study the relationship between disease severity and climate, topography, soil, and forest stand characteristics. Fog occurrence, precipitation, temperature, elevation, and slope aspect were the variables that contributed to explain most of the variability in disease severity, as indicated by both the multiple regression (r 2 = 0.57) and regression tree (RMD = 0.27) analyses. The resulting regression model was used to construct a disease prediction map. Findings agree with and formalize our previous understanding of the ecology of SNC: warmer and wetter conditions, provided that summer temperatures are relatively low, appear to increase disease severity. Both regression approaches have characteristics that can be useful in helping to improve our understanding of the ecology of SNC. The prediction model is able to produce a continuous prediction surface, suitable for hypothesis testing and assisting in disease management and research.

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.

Relationship of Pacific Madrone Sprout Growth to Productivity of Douglas-Fir Seedlings and Understory Vegetation

1990 ◽  
Vol 5 (1) ◽  
pp. 20-24 ◽  
Author(s):  
Thomas F. Hughes ◽  
John C. Tappeiner ◽  
Michael Newton
Keyword(s):  
Pseudotsuga Menziesii ◽  
Secondary Succession ◽  
Douglas Fir ◽  
Understory Vegetation ◽  
Diameter Growth ◽  
Area Index ◽  
Old West ◽  
Pacific Madrone ◽  
Relationship Of ◽  
Sprout Growth

Abstract We studied the development of Pacific madrone (Arbutus menziesii) sprout clumps of various initial densities and their effect on Douglas-fir (Pseudotsuga menziesii) seedling growth and understory vegetation. Five years after density treatments, average leaf area index (LAI) of 9-year-oldmadrone sprouts ranged from 3.6-1.0 m²/m² and total aboveground biomass from 25,630-8,390 kg/ha on the high- and low-density plots, respectively. Diameter of 9-year-old Douglas-fir was inversely related to madrone LAI and ranged from about 27 mm on the high-density plots to 54 mmin the absence of madrone. Analyses of diameter growth trends also indicated that, in the absence of madrone, Douglas-fir grew significantly (P = 0.001 to 0.023) faster than in other treatments. An index of shrub, forb, and grass density was inversely related to madrone LAI, suggesting thatunderstory species are quickly excluded from young madrone stands during secondary succession. We provide equations relating the 5-year growth of 9-year-old Douglas-fir to measures of madrone density and seedling size made when the plantation was 5 years old. West. J. Appl. For. 5(1):20-24.

Characteristics of stomatal diffusion resistance in a Douglas fir forest exposed to soil water deficits

1977 ◽  
Vol 7 (4) ◽  
pp. 595-604 ◽  
Author(s):  
C. S. Tan ◽  
T. A. Black ◽  
J. U. Nnyamah
Keyword(s):  
Soil Water ◽  
Soil Water Potential ◽  
High Stress ◽  
Vapour Pressure Deficit ◽  
Douglas Fir ◽  
Diffusion Resistance ◽  
Total Water ◽  
Pressure Potential ◽  
Relationship Of ◽  
The Relationship

As part of a 2-year study of the effect of thinning on evapotranspiration in Douglas fir (Pseudotsugamenziesii (Mirb.) Franco), the relationship between stomatal diffusion resistance (rs) and environmental variables were studied. Research was conducted in an unthinned stand (1840 stems ha−1) with negligible undergrowth and a thinned stand (840 stems ha−1) with substantial salal (Gaultheriashallon Pursh) undergrowth. During the daytime rs was mainly related to the soil water potential (ψs) and the vapour pressure deficit (v.p.d.) of the canopy air. Daytime values of rs for Douglas fir ranged from 2 to 60 s cm−1 for values of v.p.d. between 4 and 24 mb (4 and 24 × 102 Pa) and values of ψs between 0 and −12.5 bars (0 and −12.5 × 105 Pa). Although increasing rs was usually associated with decreasing pressure potential of the twig xylem (ψt), increasing rs appeared to be associated with increasing ψt when the v.p.d. was high. Stress history was found to cause a shift in the relationship of rs to ψt, but had little effect on the relationship of rs to v.p.d. and ψs. Daytime values of rs for salal ranged from 2 to 45 s cm−1. This stomatal behaviour suggests that as the soil dried out, salal transpiration accounted for an increasing fraction of the total water loss by the thinned stand.

Combined Analysis of Pathology and Hemodynamics of Human Unruptured Cerebral Aneurysm With Thin-Walled Region

2013 ◽  
Author(s):  
Yasutaka Tobe ◽  
Takanobu Yagi ◽  
Yuki Iwabuchi ◽  
Momoko Yamanashi ◽  
Kenji Takamura ◽  
...  
Keyword(s):  
Cerebral Aneurysms ◽  
Physiological Effect ◽  
Unruptured Cerebral Aneurysm ◽  
Computational Fluid Dynamics Cfd ◽  
Thin Walled ◽  
Cfd Analyses ◽  
Relationship Of ◽  
The Relationship ◽  
Sem Analyses ◽  
Cell Thickness

Cerebral aneurysms are known as the top reason of subarachnoid hemorrhage (SAH). They are studied in the medical and the engineering field to reveal their pathogenesis, progression, and rupture mechanisms1,2. The pathological studies revealed the site of predilection, rupture rate, the risk factors1, inflammation within the aneurysm, and conditions of endothelial cells (EC) in the aneurysms3. The current pathological analyses of the cerebral aneurysms are all phenomenological and it does not consider the cause-and-effect mechanisms between the mechanical stimulation and the physiological effect although hemodynamics is thought to play an important role in the mechanisms of aneurysms. One reason that the aneurysms’ mechanisms remain unsolved is because the pathology and hemodynamics are studied independently. Purpose of this study is to reveal the relationship of endothelial cell, thickness, and hemodynamics of the cerebral aneurysms by comparing the scanning electron microscope (SEM) analyses, μCT, and the computational fluid dynamics (CFD) analyses of the cerebral aneurysms.

Experimental Research on Concrete Filled Thin-Walled Steel Tube Long Columns

2008 ◽  
Vol 400-402 ◽  
pp. 551-557 ◽  
Author(s):  
Bao Zhu Cao ◽  
Yao Chun Zhang ◽  
Yue Ming Zhao
Keyword(s):  
Experimental Research ◽  
Local Buckling ◽  
Steel Tube ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Global Buckling ◽  
Thin Walled ◽  
Relationship Of ◽  
The Relationship ◽  
Theoretical Results

Experimental research on square and octagonal concrete filled thin-walled steel tube long columns of 6 specimens in axial compression and 8 specimens in eccentric compression is undertaken. The relationship of global buckling bearing capacity of the columns and local buckling of the steel tubes is obtained. The test indicates that local buckling occurs in steel tube of each column before it reaches ultimate capacity, and has little effect on global buckling performance. The ultimate load decreases obviously with the increase of slender ratio and eccentricity. The ductility of columns increases with the increase of steel ratio in composite sections. Composite beam element of ANSYS is adopted in the finite element analysis. The theoretical results are agreed well with test..

Effects of laminated root rot (Phellinusweirii) on Douglas-fir foliar chemistry

1996 ◽  
Vol 26 (8) ◽  
pp. 1440-1445 ◽  
Author(s):  
A.J. Thomson ◽  
D.G. Goodenough ◽  
H.J. Barclay ◽  
Y.J. Lee ◽  
R.N. Sturrock
Keyword(s):  
Chlorophyll A ◽  
Root Rot ◽  
Statistical Significance ◽  
Douglas Fir ◽  
Foliar Chemistry ◽  
Chlorophyll A And B ◽  
Foliage Chemistry ◽  
Relationship Of ◽  
The Relationship ◽  
Made In

To determine the effects of laminated root rot (Phellinusweirii) on Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) foliar chemistry, chlorophyll a and b, N, P, K, Ca, Mg, Mn, Fe, and foliage moisture were measured in new and old foliage from 20- to 80-year-old coastal Douglas-fir. Measurements were made in June and September of 1993 and June of 1994. Chlorophyll a and b, Ca, Fe, Mg, and Mn were higher in old foliage in both June and September, while moisture, N, and K were higher in the new foliage. The relationship of P to foliage age changed with time. Reductions in foliage moisture, chlorophyll a, and N were consistently associated with P. weirii infection in all plots, but the normal high variability in foliage chemistry made demonstration of statistical significance difficult. Within-tree variability in foliar chemistry was much higher in June than in September, especially in the new foliage.

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