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1.
Frequency of Douglas-fir bark beetle, Dendroctonus pseudotsugae Hopkins (Coleoptera: Scolytidae), attack on western larch (Lark occidentalis Nutt.) was negatively correlated with 3-carene content of the xylem oleoresin. Concentrations of all oleoresin volatiles from stem cores of standing trees were higher in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) than in western larch with the single exception of 3-carene. Successful brood production by the Douglas-fir bark beetle in standing trees of Douglas-fir but not western larch may therefore be explained, at least in part, by the high 3-carene content of western larch. Other differences between the species that might affect susceptibility to beetle attack include thinner phloem, higher phloem moisture content and larger diameter vertical resin ducts in western larch compared with Douglas-fir. Live standing western larch had no oleoresin exudation pressure, suggesting that this trait is not associated with resistance to attack by the Douglas-fir bark beetle in this species. 相似文献
2.
Richardson A 《Tree physiology》2000,20(12):825-829
Accurate estimates of root growth rates are important for root system modeling, and the spread of root systems may be an important determinant of belowground site occupancy. Estimating root system growth rates is complicated because missing, discontinuous, and false annual growth rings make root cross sections difficult to age. These irregularities can occur even in roots of dominant conifers with rare or absent stem growth ring abnormalities. Incomplete rings were noted in the root growth rings of nine co-dominant interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) trees. Coarse root (> 1.0-cm diameter) elongation rates were estimated by fitting a geometric mean regression line to ring count and lateral distance data. In all nine roots examined, the geometric mean regression slope was well within the range of the 95% confidence interval for the ordinary least squares regression of lateral distance versus age, suggesting that measurement error may have been negligible. Coarse root elongation rates (which ranged from 2.8 to 15.3 cm year(-1) and averaged 7.4 cm year(-1)) in the interior Douglas-fir trees studied were much lower than those reported by others. This discrepancy may be a result of limited soil water availability, soil heterogeneity (both soil water content and soil texture were highly variable across short distances) and fragmentation of belowground growing space. 相似文献
3.
Although tree- and stand-level estimates of forest water use are increasingly common, relatively little is known about partitioning of soil water resources among co-occurring tree species. We studied seasonal courses of soil water utilization in a 450-year-old Pseudotsuga menziesii (Mirb.) Franco-Tsuga heterophylla (Raf.) Sarg. forest in southwestern Washington State. Soil volumetric water content (theta) was continuously monitored with frequency domain capacitance sensors installed at eight depths from 0.2 to 2 m at four locations in the vicinity of each species. Vertical profiles of root distribution and seasonal and daily courses of hydraulic redistribution (HR), sap flow and tree water status were also measured. Mean root area in the upper 60 cm of soil was significantly greater in the vicinity of T. heterophylla trees. However, seasonal water extraction on a root area basis was significantly greater near P. menziesii trees at all depths between 15 and 65 cm, leading to significantly lower water storage in the upper 65 cm of soil near P. menziesii trees at the end of the summer dry season. Greater apparent efficiency of P. menziesii roots at extracting soil water was attributable to a greater driving force for water uptake rather than to differences in root hydraulic properties between the species. The dependence of HR on theta was similar in soil near individuals of both species, but seasonal maximum rates of HR were greater in soil near P. menziesii because minimum values of theta were lower, implying a steeper water potential gradient between the upper and lower soil that acted as a driving force for water efflux from shallow roots. The results provide information on functional traits relevant for understanding the ecological distributions of these species and have implications for spatial variability of processes such as soil respiration and nutrient cycling. 相似文献
4.
5.
One-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and lodgepole pine (Pinus contorta Dougl.) seedlings were grown for 17 weeks in 100-cm deep, 7.8-liter containers. Two Douglas-fir provenances, one from a wet and one from a dry site in coastal British Columbia, and two lodgepole pine provenances, one from a wet and one from a dry site in interior British Columbia, were grown in wet (522% water content) or dry (318% water content) peat/vermiculite soil in a factorial design. Each container was sealed so that water loss occurred only through the seedling. Five harvests were made at three to five week intervals and water use, dry matter increment, root length and root weight were determined at each harvest. Stomatal conductance and shoot water potentials were measured during the last 12 weeks of the experiment. Lodgepole pine seedlings had greater dry matter production, water use, stomatal conductance and new root length than Douglas-fir seedlings. New root weight of lodgepole pine seedlings exceeded that of Douglas-fir seedlings during the last five weeks of the experiment, and specific root length (root length per unit root weight) of new roots was higher for lodgepole pine seedlings throughout the experiment. Douglas-fir seedlings showed higher water use efficiency (WUE) than lodgepole pine seedlings, and both species showed higher WUE in the dry soil treatment. Douglas-fir seedlings had lower water potentials and higher water uptake rates per unit of new root length than lodgepole pine seedlings, although water uptake rates per unit of root dry weight showed little difference between species. Soil water treatment influenced specific root length of new roots, water uptake per unit of new root length, and WUE in Douglas-fir seedlings more than in lodgepole pine seedlings. 相似文献
6.
Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stumps infested with Phellinus weirii (Murr.) Gilb. were inoculated with pellets formulated from fermented barley and spores of three isolates of Trichoderma viride Pers.: Fr. After one year, Trichoderma spp. were isolated from stumps inoculated in June less frequently (12 %) than those inoculated in February (23 %) or in October (29 %). Isolations of Trichoderma spp. from stumps with advanced decay were more frequent (46 %) than from stained stumps (12 %) or from sound stumps (2 %). Isolation success was directly related to wood decay at point of sampling, nearness to source of inoculum, and nearness to stump surface. 相似文献
7.
The objectives of this study were to assess the range of genotypic variation in the vulnerability of the shoot and root xylem of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings to water-stress-induced cavitation, and to assess the trade-off between vulnerability to cavitation and conductivity per unit of stem cross-sectional area (k(s)), both within a species and within an individual tree. Douglas-fir occupies a broad range of environments and exhibits considerable genetic variation for growth, morphology, and drought hardiness. We chose two populations from each of two varieties (the coastal var. menziesii and the interior var. glauca) to represent environmental extremes of the species. Vulnerability curves were constructed for shoots and roots by plotting the percentage loss in conductivity versus water potential. Vulnerability in shoot and root xylem varied genetically with source climate. Stem xylem differed in vulnerability to cavitation between populations; the most mesic population, coastal wet (CW), was the most susceptible of the four populations. In the roots, the most vulnerable population was again CW; the interior wet (IW) population was moderately susceptible compared with the two dry populations, coastal dry (CD) and interior dry (ID). Root xylem was more susceptible to cavitation than stem xylem and had significantly greater k(s). The trade-off between vulnerability to cavitation and k(s), however, was not evident across populations. The most vulnerable population (CW) had a shoot k(s) of 0.534 +/- 0.067 &mgr;mol m(-2) s(-1) MPa(-1), compared with 0.734 +/- 0.067 &mgr;mol m(-2) s(-1) MPa(-1) for the less vulnerable CD stems. In the roots, IW was more vulnerable than ID, but had the same k(s). 相似文献
8.
Plantlets of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) had lower rates of net CO(2) uptake and higher rates of root respiration than greenhouse-grown seedlings. They also had a lower photosynthetic efficiency at high photosynthetic photon flux density, and exhibited significant depression of CO(2) uptake under water stress. The ability of plantlets to utilize high irradiance and to photosynthesize under conditions of water stress was enhanced by the presence of many roots. Carbon dioxide uptake rate increased with increasing root number, and decreased as the needle surface area/root surface area ratio decreased. High root number, low needle surface area/root surface area ratio, and elongated roots were associated with low apparent rates of shoot and root respiration. 相似文献
9.
Effects of nitrogen source on growth and activity of nitrogen-assimilating enzymes in Douglas-fir seedlings 总被引：2，自引：0，他引：2
Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were grown for 68 days in a growth chamber in nutrient solutions with ammonium, nitrate or ammonium nitrate as the nitrogen source. Among the nitrogen sources tested, whole-seedling biomass, relative growth rate (RGR), root and shoot elongation, and number of lateral roots, were greatest in seedlings grown with ammonium. In the absence of nitrogen, plant growth and formation of lateral roots were poor. Initially, glutamine synthetase, NAD-glutamate dehydrogenase and aspartate aminotransferase activities were high in young roots and shoots, but all three enzymatic activities decreased after one month of culture. In root apices, glutamine synthetase and aspartate aminotransferase activities were higher than NAD-glutamate dehydrogenase activity. Enzymatic activities were often higher in ammonium-fed seedlings than in seedings supplied with the other forms of nitrogen. Activities of all three enzymes were significantly reduced in seedlings grown in the absence of nitrogen. The beneficial effect of ammonium is discussed on the basis of its involvement in the assimilation pathways of Douglas-fir. 相似文献
10.
Philipson JJ 《Tree physiology》1988,4(2):101-108
When dormant Sitka spruce (Picea sitchensis (Bong.) Carr.) transplants were lifted from the nursery in March and transferred to favorable growing conditions in a controlled environment chamber, new roots emerged and elongated even when the plants were bark-ringed so that the roots could not receive metabolites from the shoot by phloem translocation. Carbohydrate analysis showed that starch reserves in the roots of the bark-ringed plants were depleted, indicating that these reserves provided the energy source for new root growth. The shoot also had a role in new root growth as excised root systems showed greatly reduced root growth. This response is compared to that of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in which bark-ringing prevented root growth indicating that current photosynthate is needed for new root growth. The findings are discussed in relation to the problems of establishing these species in forest plantations. 相似文献
11.
R. Siepmann 《Forest Pathology》1981,11(3):162-169
On the regeneration and infection of roots of Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) by fungi present in the soil. 167 roots in 4 stands were severed 40–60 cm from the base of the tree. At the proximal cut ends of the thick roots of the 40 years old trees on loamy sand, either replacement roots or callous tissue were formed (only a small percentage of those roots was invaded by rot causing Basidiomycetes), or no new roots and no callus were formed and root rot fungi (Fomes annosus, Coniophora puteana, Resinicium bicolor) had invaded the root sections from the soil. On the root sections of the 35 and 55 years old Douglas firs on sand, with the exception of 2 roots, neither replacement roots nor callus were formed; Fomes and Coniophora had invaded the thicker roots of the older trees from the soil. 相似文献
12.
The spatial distribution of plant-available mineral nutrients in forest soils is often highly heterogeneous. To test the hypothesis that local nutrient enrichment of soil leads to increased root proliferation in the nutrient-rich soil zone, we studied the effects of nutrient enrichment on the growth and nutrient concentrations of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) roots. Three-year-old seedlings were grown for 9 months in split-root containers filled with nutrient-poor forest mineral soil, with one side supplemented with additional mineral nutrients. Root dry weight and root length in Scots pine and Norway spruce were increased in the nutrient-supplemented soil compared with the nonsupplemented side, whereas root growth in Douglas-fir was unaffected by nutrient enrichment. Of the three species examined, Norway spruce exhibited the highest root and shoot growth and the highest nutrient demand. Specific root length (m g(-1)) and the number of root tips per unit root length were not affected by local nutrient addition in any of the species. Despite increased root growth in Norway spruce and Scots pine in nutrient-supplemented soil, their root systems contained similar nutrient concentrations on both sides of the split-root container. Thus, coniferous trees may respond to local nutrient supply by increased root proliferation, but the response varies depending on the species, and may only occur when trees are nutrient deficient. As a response to local nutrient enrichment, increases in root dry matter or root length may be better indicators of pre-existing nutrient deficiencies in conifers than increases in root nutrient concentrations. 相似文献
13.
Mousseaux Mark R. Dumroese R. Kasten James Robert L. Wenny David L. Knudsen Guy R. 《New Forests》1998,15(1):11-21
Inoculating a soilless medium with encapsulated Trichoderma harzianum did not affect any aspect of Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) seed germination or subsequent growth. Results of inoculating medium with a known pathogenic isolate of Fusarium oxysporum alone, or concurrently with T. harzianum, were the same: high levels of damping-off, low amounts of hypocotyl and root disease in midsummer, and significant reductions in height growth. When seedling roots grew through T. harzianum-inoculated medium before growing into a mixture of T. harzianum-F. oxysporum-inoculated medium, mortality was reduced about 50%. Although contamination by resident Fusarium occurred, subsequent root colonization was significantly reduced in T. harzianum-amended growing medium. 相似文献
14.
Apple M Tiekotter K Snow M Young J Soeldner A Phillips D Tingey D Bond BJ 《Tree physiology》2002,22(2-3):129-136
Morphological differences between old-growth trees and saplings of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) may extend to differences in needle anatomy. We used microscopy with image analysis to compare and quantify anatomical parameters in cross sections of previous-year needles of old-growth Douglas-fir trees and saplings at the Wind River Canopy Crane site in Washington and at three sites in the Cascade Mountains of Oregon. We also compared needle anatomy across a chronosequence of 10-, 20-, 40- and 450-year-old Douglas-fir trees from the Wind River site. Anatomy differed significantly between needles of old-growth trees and saplings at all sites, suggesting a developmental change in needle anatomy with increasing tree age. Compared with needles of old-growth trees, needles of saplings were longer and had proportionately smaller vascular cylinders, larger resin canals and few hypodermal cells. Astrosclereids, which sequester lignin in their secondary cell walls and occupy space otherwise filled by photosynthetic cells, were scarce in needles of saplings but abundant in needles of old-growth trees. Needles of old-growth trees had an average of 11% less photosynthetic mesophyll area than needles of saplings. The percentage of non-photosynthetic area in needles increased significantly with increasing tree age from the chronosequence of 10-, 20-, 40- and 450-year-old trees at the Wind River site. This reduction in photosynthetic area may contribute to decreased growth rates in old trees. 相似文献
15.
Conifers have defenses such as the production of phenolic compounds and resins that can be induced by bark beetles and other invading organisms, but the signaling agents involved are unknown. The anatomical effects of methyl jasmonate (MJ), a potent inducer of certain plant defenses, were compared with wounding of the bark of 12-15-year-old trees of five conifer species. Wounding in all species resulted in tissue necrosis and wound periderm development immediately around the wound site. One cm from the wound, swelling of phloem polyphenolic parenchyma cells and phenolic accumulation were observed in Pseudotsuga menziesii (Mirb.) Franco, Picea pungens Engelman, Larix occidentalis Nutt. and Pinus monticola Douglas ex D. Don, but not in Taxus brevifolia Nutt. Traumatic resin ducts were formed in response to wounding in three species of Pinaceae, but not in P. monticola, which formed irregular clusters of cells rather than ducts. Taxus brevifolia did not form resin ducts in response to either wounding or MJ treatment. In the Pinaceae species studied, surface application of 100 mM MJ caused similar anatomical changes to those observed in response to wounding, including phenolic accumulation, cell swelling and traumatic resin duct formation, but it did not induce a wound periderm. Traumatic resin ducts differed in size among the study species, ranging from small in L. occidentalis to very large in P. menziesii. In P. menziesii, P. pungens and L. occidentalis, traumatic resin ducts were more abundant after MJ treatment than after wounding. We conclude that the octadecanoid pathway is likely involved in defense responses in stems of the Pinaceae, but not necessarily in other taxa. 相似文献
16.
We compared hydraulic architecture, photosynthesis and growth in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), a shade-intolerant species, and western hemlock (Tsuga heterophylla (Raf.) Sarg.), a shade-tolerant species, to study the temporal pattern of release from suppressive shade. In particular, we sought to determine whether hydraulic architecture or photosynthetic capacity is most important in constraining release. The study was conducted at two sites with mixed stands of 10- to 20-year-old Douglas-fir and western hemlock. At one site, the stand had been thinned allowing release of the understory trees, whereas at the other site, the stand remained unthinned. Douglas-fir had lower height growth (from 1998-2003) and lower relative height growth (height growth from 1998 to 2003/height in 1998) than western hemlock. However, relative height growth of released versus suppressed trees was higher in Douglas-fir (130%) than in western hemlock (65%), indicating that, although absolute height growth was less, Douglas-fir did release from suppression. Release seemed to be constrained initially by a limited photosynthetic capacity in both species. Five years after release, Douglas-fir trees had 14 times the leaf area and 1.5 times the leaf nitrogen concentration (N (area)) of suppressed trees. Needles of released western hemlock trees had about twice the maximum assimilation rate (A (max)) at ambient [CO(2)] as needles of suppressed trees and exhibited no photoinhibition at the highest irradiances. After release, trees increased in leaf area, leaf N concentration and overall photosynthetic capacity. Subsequently, hydraulic architecture appeared to constrain release in Douglas-fir and, to a lesser extent, in western hemlock. Released trees had significantly less negative foliar delta(13)C values than suppressed trees and showed a positive relationship between leaf area:sapwood area ratio (A (L)/A (S)) and delta(13)C, suggesting that trees with more leaf area for a given sapwood area experienced a stomatal limitation on carbon gain. Nonetheless, these changes had no significant effects on leaf specific conductivities of suppressed versus released trees of either species, but leaf specific root conductance was significantly lower in released Douglas-fir. 相似文献
17.
Roots of hardwoods have been shown to be more vulnerable to xylem cavitation than stems. This study examined whether this pattern is also observed in a conifer species. Vulnerability to cavitation was determined from the pressure required to inject air into the vascular system of hydrated roots and stems, and reduce hydraulic conductance of the xylem. According to the air-seeding hypothesis for the cavitation mechanism, these air pressures predict the negative xylem pressure causing cavitation in dehydrating stems. This was evaluated for stems of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and white fir (Abies concolor (Gord. & Glend.) Lindl.). The air-injection method was applied to roots and stems of different sizes and positions in Douglas-fir trees. Roots, especially smaller roots with a xylem diameter < 5 mm, were more vulnerable to cavitation than stems. Mean cavitation pressure for smaller roots was -2.09 +/- 0.42 versus -3.80 +/- 0.19 MPa for larger roots (> 8 mm diameter). Within the shoot system, smaller stems (< 5 mm diameter) were most vulnerable to cavitation, having a mean cavitation pressure of -4.23 +/- 0.565 versus -5.27 +/- 0.513 MPa for large stems (> 8 mm diameter). There was no correlation between tracheid diameter and mean cavitation pressure within root or stem systems, despite larger tracheid diameters in roots (23.3 +/- 3.9 micro m) than in stems (9.2 +/- 1.6 micro m). Smaller safety margins from cavitation in roots may be beneficial in limiting water use during mild drought, and in protecting the stem from low xylem pressures during extreme drought. 相似文献
18.
Greenhouse-cultured, container-grown seedlings of Aleppo pine (Pinus halepensis Mill.), radiata pine (Pinus radiata D. Don), and interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) were cold acclimated and deacclimated in growth chambers over 24 weeks. Needle and root cold hardiness and root growth potential (RGP) were measured weekly. Root, needle and stem analyses for soluble sugars and starch were performed biweekly. In all tissues, there was a close correspondence between cold hardiness and the absolute concentration of soluble sugars, as well as between the increase and decrease in concentration of soluble sugars during cold hardening and dehardening, respectively, supporting the theory that soluble sugars function as cryoprotectants in plant tissues. The magnitude of starch concentration did not parallel the magnitude of the cold hardiness attained, and changes in starch concentration were related to production and consumption factors, rather than timing of changes in cold hardiness. The rise and fall of RGP paralleled the rise and fall of total carbohydrate concentration in roots. The behavior of the three species was surprisingly similar, considering the different climates to which they are adapted. 相似文献
19.
We compared growth rates among mature interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) trees showing resistance or susceptibility to defoliation caused by western spruce budworm (Choristoneura occidentalis Freeman), and among clones and half-sib seedling progeny of these trees in a greenhouse. We also investigated bud burst phenology and photosynthetic responses of clones to budworm defoliation in greenhouse experiments. Resistant mature trees had a higher radial growth rate than susceptible trees, especially during periods of budworm defoliation. Clones from resistant trees grew larger crowns than clones from susceptible trees, whereas stem base diameter at the ground line and height did not differ. Half-sib seedling progeny from resistant trees had larger stem diameter, height, and total biomass than progeny from susceptible trees. Mean 5-year radial growth increment of mature trees was more strongly correlated with growth of seedlings than with growth of clones. Clones from resistant trees had later bud burst than clones from susceptible trees, and budworm defoliation of clones depended on the degree of synchrony between bud burst phenology and budworm larval feeding. Clones of resistant and susceptible mature trees showed similar responses of net photosynthetic rate to 2 years of budworm defoliation. We conclude that phenotypic differences in crown condition of Douglas-fir trees following western spruce budworm defoliation are influenced by tree genotype and that high growth rate and late bud burst phenology promote tree resistance to budworm defoliation. 相似文献
20.
A. Zamani R. Sturrock A. K. M. Ekramoddoullah S. B. Wiseman M. Griffith 《Forest Pathology》2003,33(5):299-316
Extracellular proteins were extracted from Phellinus weirii infected Douglas‐fir (Pseudotsuga menziesii var. menziesii) roots and needles to examine endochitinase activity. Chitinases have been associated with the plant's defence response against fungal attack because they hydrolyse chitin, a structural component of fungal cell walls. Protein separation using sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) followed by Western immunoblot analysis using a polyclonal antibody specific to an endochitinase‐like protein (ECP) resulted in the detection of up to three polypeptides between 27 and 30 kDa in size. Two‐dimensional gel electrophoresis (2‐D PAGE) followed by Western immunoblot analysis revealed that the apoplastic fluid contained multiple ECP isoforms with isoelectric points (pIs) ranging from 5.3 to 5.8 and molecular masses of 27–30 kDa. Chitinase activity in needle and root tissues was measured spectrophotometrically using a colorimetric assay. A gel overlay technique using glycol chitin as a substrate for endochitinase was applied to confirm that the ECP antibody detected an enzymatically active protein. The apoplastic fluid collected from P. weirii‐infected winter Douglas‐fir needles showed anti‐freeze activity and seasonal analysis of needle tissue showed some evidence of ECP accumulation in winter months. ECP was distributed systemically throughout the tree. Increased levels of endochitinase activity in the region of P. weirii infection supports a physiological role for ECP in the plant defence response. 相似文献