| induction of listeria monocytogenes infection by the consumption of ponderosa pine needles. | an infectious microorganism, identified as listeria monocytogenes, has been isolated from the bloodstream of pregnant mice fed a diet containing pinus ponderosa needles. when the isolate was injected into pregnant mice, reproductive dysfunction and other changes, including speckled livers, spleen atrophy, and hemorrhagic intestines, appeared to mimic the signs of the disease in pregnant mice fed pine needles. moreover, these pathological changes are similar to those observed in cattle and other ... | 1979 | 113341 |
| inheritance of isozyme variation and heterozygosity in pinus ponderosa. | techniques are presented to detect 23 isozyme loci in the long-lived perennial plant, ponderosa pine. meiotically derived megagametophyte from seeds is used to examine directly the segregation of allelic variants. approximately seven seeds were initially examined for 12 enzymes from each of 47 trees from ten stands throughout the northern rocky mountain region. additional seeds were also examined from selected families to confirm the inheritance of observed electrophoretic variants at 13 polymor ... | 1979 | 486070 |
| pine-needle(pinus ponderosa)-induced abortion in range cattle. | | 1972 | 5077532 |
| oleosins in the gametophytes of pinus and brassica and their phylogenetic relationship with those in the sporophytes of various species. | oleosins, which are structural proteins on the surface of intracellular oil bodies, have been found in the sporophytic seeds of angiosperms. here, we report an oleosin from the female gametophyte of gymnosperm pinus ponderosa laws. seed and another oleosin from the male gametophyte of brassica napus l. with the pine seed gametophyte, we identified two putative oleosins of 15 and 10 kda, which are similar to the oleosins in angiosperm seeds in terms of their presence in the oil bodies in massive ... | 1994 | 7764875 |
| organophosphate flame retardants in needles of pinus ponderosa in the sierra nevada foothills | | 1996 | 8875831 |
| response of stomatal conductance to drought in ponderosa pine: implications for carbon and ozone uptake. | to gain insight into the limitations imposed by a typical mediterranean-climate summer drought on the uptake of carbon and ozone in the ponderosa pine (pinus ponderosa dougl. ex laws.) ecosystem, we compared diurnal trends in leaf physiology of young trees in a watered and a control plot located in the sierra nevada mountains, ca, usa (blodgett forest, 38 degrees 53' n, 120 degrees 37' w, 1315 m elevation). predawn water potential of trees in the watered plot remained above -0.3 mpa throughout t ... | 2001 | 11262925 |
| blue wild-rye grass competition increases the effect of ozone on ponderosa pine seedlings. | individual ponderosa pine (pinus ponderosa dougl. ex laws.) seedlings were grown in mesocosms with three densities of blue wild-rye grass (elymus glaucus buckl.) (equivalent to 0, 32 or 88 plants m-2) to determine if the presence of a natural competitor alters the response of ponderosa pine seedlings to ozone. after 3 years of ozone exposure, grass presence reduced total ponderosa pine dry mass by nearly 50%, whereas ozone alone had no significant effect on ponderosa pine growth. the combination ... | 2001 | 11262923 |
| ecosystem respiration in a young ponderosa pine plantation in the sierra nevada mountains, california. | we estimated total ecosystem respiration from a ponderosa pine (pinus ponderosa dougl. ex laws.) plantation in the sierra nevada mountains near georgetown, california, from june to october, 1998. we apportioned ecosystem respiration among heterotrophic, root, stem and foliage based on relationships for each component that considered microclimate and vegetation characteristics. we measured each respiration component at selected sampling points, and scaled the measurements up to the ecosystem base ... | 2001 | 11262922 |
| carbon dioxide and water vapor exchange by young and old ponderosa pine ecosystems during a dry summer. | we investigated key factors controlling mass and energy exchange by a young (6-year-old) ponderosa pine (pinus ponderosa laws.) plantation on the west side of the sierra nevada mountains and an old-growth ponderosa pine forest (mix of 45- and 250-year-old trees) on the east side of the cascade mountains, from june through september 1997. at both sites, we operated eddy covariance systems above the canopy to measure net ecosystem exchange of carbon dioxide and water vapor, and made concurrent met ... | 2001 | 11262921 |
| use of a simulation model and ecosystem flux data to examine carbon-water interactions in ponderosa pine. | drought stress plays an important role in determining both the structure and function of forest ecosystems, because of the close association between the carbon (c) and hydrological cycles. we used a detailed model of the soil-plant-atmosphere continuum to investigate the links between carbon uptake and the hydrological cycle in a mature, open stand of ponderosa pine (pinus ponderosa dougl. ex laws.) at the metolius river in eastern oregon over a 2-year period (1996-1997). the model was parameter ... | 2001 | 11262920 |
| changes in physiological attributes of ponderosa pine from seedling to mature tree. | plant physiological models are generally parameterized from many different sources of data, including chamber experiments and plantations, from seedlings to mature trees. we obtained a comprehensive data set for a natural stand of ponderosa pine (pinus ponderosa laws.) and used these data to parameterize the physiologically based model, tregro. representative trees of each of five tree age classes were selected based on population means of morphological, physiological, and nearest neighbor attri ... | 2001 | 11262919 |
| conditioned food aversions: principles and practices, with special reference to social facilitation. | conditioned food aversion is a powerful experimental tool to modify animal diets. we have also investigated it as a potential management tool to prevent livestock from grazing poisonous plants such as tall larkspur (delphinium barbeyi), white locoweed (oxytropis sericea) and ponderosa pine (pinus ponderosa) on western us rangelands. the following principles pertain to increasing the strength and longevity of aversions: mature animals retain aversions better than young animals; novelty of the pla ... | 1999 | 10817148 |
| antioxidants and protective pigments of pinus ponderosa needles at gradients of natural stresses and ozone in the san bernardino mountains in california. | at the san bernardino mountains, california, a well documented gradient of ozone pollution overlays a natural stress gradient from mesic to dry and from lower elevation to higher elevation sites. in contrast to gradient studies in european regions, the highest ambient ozone levels are observed at low elevation and more mesic locations. in the present study, antioxidative and photoprotective systems in pinus ponderosa needles were investigated at three plots--dw (1725 m, high ozone impact, mesic ... | 1999 | 10694049 |
| antimicrobial activity of some pacific northwest woods against anaerobic bacteria and yeast. | extracts of woods commonly used for animal bedding were tested for antimicrobial activity. essential oils from alaska cedar (chamaecyparis nootkatensis), western juniper (juniperus occidentalis) and old growth douglas fir (pseudotsuga menziesii) as well as methanol extracts of wood from these trees plus western red cedar (thuja plicata) and ponderosa pine (pinus ponderosa) were tested for antimicrobial activity against anaerobic bacteria and yeast. the test microbes included fusobacterium necrop ... | 2001 | 11746838 |
| studies into abstract properties of individuals. iii. a study of factors affecting emergence. | eighteen individuals of pinus ponderosa lawson were analyzed for emergence, a difference in organization between the lower and higher levels of a within-plant hierarchy. the variables used were six distance measurements taken from needle cross sections, and organization was evaluated using angles between eigenvectors and a vector of isometry. sixteen of 18 individuals analyzed showed emergence. variation was shown in the degree of emergence, the between-level difference in organization. variatio ... | 1999 | 10506461 |
| abortifacient effects of a unique class of vasoactive lipids from pinus ponderosa needles. | pinus ponderosa needle (pn) ingestion by late pregnant cows results in decreased uterine blood flow, premature parturition, and retained placentae. further, plasma from pn-fed cows increases caruncular arterial tone (i.e., induces prolonged contraction) in an isolated perfused bovine placentome. a novel class of vasoactive lipids was isolated and identified using a bovine placentome assay-guided fractionation of ch2cl2 extracts of pn. placentome perfusion tests indicated that 1-12-dodecanedioyl- ... | 1999 | 10461998 |
| effects of feeding beef females supplemental fat during gestation on cold tolerance in newborn calves. | effects of prepartum fat supplementation of the dam on cold tolerance of calves were determined in two studies. in exp. 1, 22 f1, crossbred heifers gestating f2 calves received diets containing either 1.7 or 4.7% dietary fat starting at d 230+/-2d of gestation. safflower seeds (carthamus tinctorius) containing 37% oil with 79% linoleic acid were the supplemental fat source in isocaloric-isonitrogenous diets. calves were separated from their dams at birth, fed pooled dairy-cow colostrum, muzzled ... | 1999 | 10328345 |
| ponderosa pine and broom snakeweed: poisonous plants that affect livestock. | ponderosa pine (pinus ponderosa) and the snakeweeds (gutierrezia sarothrae and g. microcephala) are two groups of range plants that are poisonous to livestock. ponderosa pine causes late-term abortions in cattle, and the snakeweeds are toxic and also cause abortions in cattle, sheep, and goats. research is underway at the usda-ars-poisonous plants research laboratory to better understand livestock poisonings caused by grazing ponderosa pine needles and the snakeweeds and to provide methods of re ... | 1999 | 10091125 |
| alteration of foliar flavonoid chemistry induced by enhanced uv-b radiation in field-grown pinus ponderosa, quercus rubra and pseudotsuga menziesii. | chromatographic analyses of foliage from several tree species illustrate the species-specific effects of uv-b radiation on both quantity and composition of foliar flavonoids. pinus ponderosa, quercus rubra and pseudotsuga menziesii were field-grown under modulated ambient (1x) and enhanced (2x) biologically effective uv-b radiation. foliage was harvested seasonally over a 3-year period, extracted, purified and the flavonoid fraction applied to a mu bondapak/c(18) column hplc system sampling at 2 ... | 2002 | 11897512 |
| abortifacient effects of lodgepole pine (pinus contorta) and common juniper (juniperus communis) on cattle. | lodgepole pine (pinus contorta) and common juniper (juniperus communis) contain high levels of isocupressic acid that has been identified as the abortifacient component of ponderosa pine needles in cattle. therefore, the abortifacient potential of p contorta and j communis needles was tested in feeding trials with pregnant cattle. cows (2 groups of 2 each) were fed by gavage 4.5-5.5 kg/d ground dry needles from either p contorta or j communis starting on gestation day 250. isocupressic acid (ica ... | 1998 | 9778758 |
| effects of ingestion of pine needles (pinus ponderosa) by late-pregnant beef cows on potential sensitive ca2+ channel activity of caruncular arteries. | cows were fed either a control (n = 6) or pine needle (n = 12) diet beginning on day 249 of pregnancy. on day 3 and day 5 of feeding, control-fed and pine needle-fed cows were slaughtered and placentomes were collected for in vitro perfusion of the caruncular artery. potential sensitive ca2+ channel (psc) activity as well as the responsiveness to phenylephrine (alpha 1-adrenergic agonist) and adrenaline (alpha 1- and alpha 2-adrenergic agonist) were determined. selected gravid uterine tissues (e ... | 1993 | 8393931 |
| effect of feeding ponderosa pine needle extracts and their residues to pregnant cattle. | solvents including ethanol, methylene chloride, acetone, hexane, and hot and cold water were used in separate procedures to extract needles and bark from ponderosa pine (pinus ponderosa l.) to determine which system was optimal for the extraction of abortifacient compound(s). the extracts and residues therefrom were fed by gavage to pregnant cows beginning at day 250 of gestation. after methylene chloride extraction, the pine needle residue fed by gavage failed to abort 4 cows. subsequently, 4 c ... | 1994 | 8313706 |
| pine needle abortion in cattle: effects of diet variables on consumption of pine needles and parturition response. | cows that consume needles from pinus ponderosa (pn) abort, but little is known about variables that affect consumption or response. these experiments were conducted to test the effects of several variables on pine needle-induced abortion. cows were placed on experiment at 250 d of pregnancy and were either given ad libitum (al) access to pn separate from other feed sources or the pn were ground and fed (2 kg.cow-1.d-1) mixed with the diet. in exp. 1, cows were assigned to a 2 x 2 factorial exper ... | 1994 | 8014143 |
| abortifacient response and plasma vasoconstrictive activity after feeding needles from ponderosa pine trees to cattle and sheep. | consumption of needles from pinus ponderosa (pn) during late pregnancy causes cattle, but not sheep, to abort. this differential response may be caused by differences in ruminal microflora or postabsorptive metabolism. pine needles were fed (2 kg.cow-1.d-1 or .4 kg.ewe-1.d-1) mixed with corn silage. in exp. 1, cows were assigned at 250 d of pregnancy to feed treatments (t): 1) silage, 2) pn+silage, or 3) pretreated with sheep ruminal fluid and fed pn+silage. interval to parturition was 34.3, 11. ... | 1995 | 7592097 |
| embryo resorptions in mice induced by diterpene resin acids of pinus ponderosa needles. | ingestion of hexane extract of pinus ponderosa needles causes reproductive failure in mice during the early stages of gestation. virgin mice of the icr strain were mated with males of proven fertility. the day the copulatory plug was observed was designated day 1 of gestation. hexane extracts were administered daily via stomach tube at various concentrations and for various feeding periods. implantation sites were stained by injections of pontamine sky blue dye on day 8 of gestation, fifteen min ... | 1981 | 7226845 |
| pathological effects of pine needle ingestion in pregnant mice. | consumption of ponderosa pine (pinus ponderosa) needles causes reproductive dysfunction in mice during early and late gestation. consumption during early gestation results in considerable embryotoxicity which is not a result of starvation. temporary loss of coordination and lethargy are observed in the females. consumption of the pine needle diet results in a weight loss which persists throughout gestation. feeding the pine needle diet from the tenth day of gestation results in spleen atrophy ob ... | 1982 | 7083861 |
| myo-inositol-1-phosphate synthase from pine pollen: sulfhydryl involvement at the active site. | myo-inositol-1-phosphate synthase [ec 5.5.1.4; 1l-myo-inositol-1-phosphate lyase, (isomerizing)] from pinus ponderosa pollen has been partially purified and characterized. it has a ph optimum between 7.25 and 7.75. the km for d-glucose 6-phosphate (nad+ constant at 1 mm) is 0.33 mm. inhibition by p-chloromercuribenzoate and n-ethylmaleimide, and partial protection against this inhibition by d-glucose 6-phosphate in the presence of nad+, suggests that there is sulfhydryl group involvement at the ... | 1984 | 6732239 |
| effects of ponderosa pine needle ingestion of uterine vascular function in late-gestation beef cows. | consumption of ponderosa pine (pinus ponderosa) needles (pn) by beef cows during late gestation results in premature delivery in association with profound constriction of the caruncular arterial bed. further, pn extracts and plasma from pn-fed cows increase uterine arterial tone in vitro. uterine arterial tone is a measure of the arterial resistance to stretch and controls the baseline rate of flow through the vascular bed. uterine arterial tone results from the uptake of extracellular ca2+ into ... | 1992 | 1526929 |
| ponderosa pine needle-induced parturition in cattle. | needles of the ponderosa pine (pinus ponderosa) induce premature parturition in cattle when ingested during late pregnancy, especially during the third trimester. the closer to term, the more likely that pine needles will induce parturition. experiments were designed to describe the clinical signs and behavior associated with ingestion of pine needles. pine needles adversely affected only pregnant cows and did not seem to affect nonpregnant, cycling cows, sheep, goats, or rabbits. premature part ... | 1992 | 1526928 |
| effects of feeding ponderosa pine needles during pregnancy: comparative studies with bison, cattle, goats, and sheep. | four experiments were conducted to determine the effect of feeding dried pine needles (pinus ponderosa; pn) on the abortion rate of ruminants. in exp. 1, cattle were fed 5.4 kg of pn daily for 21 d starting at 116, 167, 215, or 254 d of pregnancy. the pn did not cause abortions when started at 116 d; thereafter, the percentage of cows that aborted increased linearly, and the interval to abortion decreased linearly (both p < .01); all cows fed pn beginning at 254 d aborted. in exp. 2, cattle were ... | 1992 | 1459912 |
| seasonal changes in above- and belowground carbohydrate concentrations of ponderosa pine along a pollution gradient. | seasonal patterns of carbohydrate concentration in coarse and fine roots, stem or bole, and foliage of ponderosa pine (pinus ponderosa laws) were described across five tree-age classes from seedlings to mature trees at an atmospherically clean site. relative to all other tree-age classes, seedlings exhibited greater tissue carbohydrate concentration in stems and foliage, and greater shifts in the time at which maximum and minimum carbohydrate concentration occurred. to determine the effect of en ... | 2001 | 11303648 |
| xylem conductivity and vulnerability to cavitation of ponderosa pine growing in contrasting climates. | we examined the effects of increased transpiration demand on xylem hydraulic conductivity and vulnerability to cavitation of mature ponderosa pine (pinus ponderosa laws.) by comparing trees growing in contrasting climates. previous studies determined that trees growing in warm and dry sites (desert) had half the leaf/sapwood area ratio (a(l)/a(s)) and more than twice the transpiration rate of trees growing in cool and moist sites (montane). we predicted that high transpiration rates would be ass ... | 2000 | 11303576 |
| multivariate patterns of biochemical responses of pinus ponderosa trees at field plots in the san bernardino mountains, southern california. | most environmental stress conditions promote the production of potentially toxic active oxygen species in plant cells. plants respond with changes in their antioxidant and photoprotective systems. antioxidants and pigments have been widely used to measure these responses. because trees are exposed to multiple man-made and natural stresses, their responses are not reflected by changes in single stress markers, but by complex biochemical changes. to evaluate such response patterns, explorative mul ... | 2001 | 11262924 |
| cytonuclear disequilibrium and genetic drift in a natural population of ponderosa pine. | we measured the cytonuclear disequilibrium between 11 nuclear allozyme loci and both mitochondrial and chloroplast dna haplotypes in a natural population of ponderosa pine (pinus ponderosa, laws). three allozyme loci showed significant associations with mtdna variation, while two other loci showed significant association with cpdna. however, the absolute number of individuals involved in any of the associations was small, such that in none of the nuclear-organellar combinations was the differenc ... | 2001 | 11404345 |
| clinal differentiation and putative hybridization in a contact zone of pinus ponderosa and p. arizonica (pinaceae). | the widely distributed pinus subsection ponderosae is a species complex that has a transition zone among taxa in the southwestern united states. in southern arizona and new mexico at least two recognized taxa, pinus ponderosa var. scopulorum and pinus arizonica or p. ponderosa var. arizonica, are known to coexist in close proximity. in this study, we report the existence of populations where the taxa are sympatric. one of the key characteristics distinguishing taxa is the number of needles per f ... | 2001 | 11410469 |
| biosynthesis of 2-methyl-3-buten-2-ol emitted from needles of pinus ponderosa via the non-mevalonate doxp/mep pathway of isoprenoid formation. | the volatile hemiterpene 2-methyl-3-buten-2-ol (mbo) is emitted from the needles of several pine species from the western united states and contributes to ozone formation in the atmosphere. it is synthesised enzymatically from dimethylallyl diphosphate (dmapp). we show here that needles of pinus ponderosa laws. incorporated [1-2h1]-1-deoxy-d-xylulose (d-dox) into the emitted mbo, but not d,l-[2-13c]mevalonic acid lactone. furthermore, mbo emission was inhibited by fosmidomycin, a specific inhibi ... | 2001 | 11469599 |
| family differences in height growth and photosynthetic traits in three conifers. | we investigated variation in height growth, gas exchange, chlorophyll fluorescence and leaf stable carbon isotope ratio among wind-pollinated progenies of douglas-fir (pseudotsuga menziesii (mirb.) franco var. glauca), ponderosa pine (pinus ponderosa dougl. ex laws.) and western white pine (pinus monticola dougl. ex d. don) from a small group of contiguous stands on the priest river experimental forest in northern idaho. photosynthetic variables differed between height classes in the pines, but ... | 2001 | 11470658 |
| development of enzyme-linked immunosorbent assays for isocupressic acid and serum metabolites of isocupressic acid. | the consumption of ponderosa pine (pinus ponderosa), lodgepole pine (pinus contorta), common juniper (juniperus communis), and monterey cypress (cupressus macrocarpa) causes abortions in pregnant cattle. recent studies have identified isocupressic acid (1) as the primary abortificient compound in these plants. in vitro and in vivo studies using rumen and blood have shown isocupressic acid (1) is rapidly metabolized to agathic acid (3), dihydroagathic acid (4), and tetrahydroagathic acid (5). rap ... | 2003 | 12744647 |
| leaf area distribution and radiative transfer in open-canopy forests: implications for mass and energy exchange. | leaf area and its spatial distribution are key canopy parameters needed to model the radiation regime within a forest and to compute the mass and energy exchange between a forest and the atmosphere. a much larger proportion of available net radiation is received at the forest floor in open-canopy forests than in closed-canopy forests. the proportion of ecosystem water vapor exchange (lambda e) and sensible heat exchange from the forest floor is therefore expected to be larger in open-canopy fore ... | 2001 | 11498325 |
| time-series analysis of delta13c from tree rings. i. time trends and autocorrelation. | univariate time-series analyses were conducted on stable carbon isotope ratios obtained from tree-ring cellulose. we looked for the presence and structure of autocorrelation. significant autocorrelation violates the statistical independence assumption and biases hypothesis tests. its presence would indicate the existence of lagged physiological effects that persist for longer than the current year. we analyzed data from 28 trees (60-85 years old; mean = 73 years) of western white pine (pinus mon ... | 2001 | 11581016 |
| rapidly eroding piñon-juniper woodlands in new mexico: response to slash treatment. | the piñon (pinus edulis engelm.)-juniper [juniperus monosperma (engelm.) sarg.] woodlands of bandelier national monument are experiencing accelerated erosion. earlier studies suggest that causes of these rapidly eroding woodlands are related to an unprecedented rapid transition of ponderosa pine (pinus ponderosa c. lawson) savanna to piñon-juniper woodlands as a result of cumulative historical effects of overgrazing, fire suppression, and severe drought. to study the effectiveness of slash treat ... | 2003 | 12931884 |
| composition of gum turpentines of pines. xix. a report on pinus ponderosa from arizona, colorado, south dakota, and northern idaho. | | 1954 | 13174442 |
| chemical composition of gum turpentines of pines. xxix. a report on pinus ponderosa from five localities: central idaho, central montana, southeastern wyoming, northwestern nebraska, and central eastern colorado. | | 1958 | 13549282 |
| anti-oestrogenic activity in yellow pine needles (pinus ponderosa). | | 1964 | 14102667 |
| interactive effects of co2 and o3 on a ponderosa pine plant/litter/soil mesocosm. | to study individual and combined impacts of two important atmospheric trace gases, co2 and o3, on c and n cycling in forest ecosystems; a multi-year experiment using a small-scale ponderosa pine (pinus ponderosa laws.) seedling/soil/litter system was initiated in april 1998. the experiment was conducted in outdoor, sun-lit chambers where aboveground and belowground ecological processes could be studied in detail. this paper describes the approach and methodology used, and presents preliminary da ... | 2001 | 11789925 |
| joint effects of elevated levels of ultraviolet-b radiation, carbon dioxide and ozone on plants. | there is growing interest regarding the joint effects of elevated levels of surface ultraviolet b (uv-b) radiation, carbon dioxide (co2) and ozone (o3) on plants. our current knowledge of this subject is too limited to draw any specific conclusions, although one might state that such effects are likely to be highly species dependent and may be more than additive, additive or less than additive. there are a number of uncertainties associated with the experimental protocols used and the conclusion ... | 2003 | 14743861 |
| respiratory potential in sapwood of old versus young ponderosa pine trees in the pacific northwest. | our primary objective was to present and test a new technique for in vitro estimation of respiration of cores taken from old trees to determine respiratory trends in sapwood. our secondary objective was to quantify effects of tree age and stem position on respiratory potential (rate of co2 production of woody tissue under standardized laboratory conditions). we extracted cores from one to four vertical positions in boles of +200-, +50- and +15-year-old pinus ponderosa dougl. ex laws. trees. core ... | 2002 | 11830407 |
| response of old-growth conifers to reduction in stand density in western oregon forests. | the positive growth response of healthy young trees to density reduction is well known. in contrast, large old trees are usually thought to be intrinsically limited in their ability to respond to increased growing space; therefore, density reduction is seldom used in stands of old-growth trees. we tested the null hypothesis that old-growth trees are incapable of responding with increased growth following density reduction. the diameter growth response of 271 douglas-fir (pseudotsuga menziesii (m ... | 2002 | 11830410 |
| water limitations to carbon exchange in old-growth and young ponderosa pine stands. | we investigated the impact of seasonal soil water deficit on the processes driving net ecosystem exchange of carbon (nee) in old-growth and recently regenerating ponderosa pine (pinus ponderosa doug. ex laws.) stands in oregon. we measured seasonal patterns of transpiration, canopy conductance and nee, as well as soil water, soil temperature and soil respiration. the old-growth stand (o) included two primary age classes (50 and 250 years), had a leaf area index (lai) of 2.1 and had never been lo ... | 2002 | 11830415 |
| soil compaction effects on water status of ponderosa pine assessed through 13c/12c composition. | soil compaction is a side effect of forest reestablishment practices resulting from use of heavy equipment and site preparation. soil compaction often alters soil properties resulting in changes in plant-available water. the use of pressure chamber methods to assess plant water stress has two drawbacks: (1) the measurements are not integrative; and (2) the method is difficult to apply extensively to establish seasonal soil water status. we evaluated leaf carbon isotopic composition (delta13c) as ... | 2002 | 11986049 |
| effects of branch height on leaf gas exchange, branch hydraulic conductance and branch sap flux in open-grown ponderosa pine. | recent studies have shown that stomata respond to changes in hydraulic conductance of the flow path from soil to leaf. in open-grown tall trees, branches of different heights may have different hydraulic conductances because of differences in path length and growth. we determined if leaf gas exchange, branch sap flux, leaf specific hydraulic conductance, foliar carbon isotope composition (delta13c) and ratios of leaf area to sapwood area within branches were dependent on branch height (10 and 25 ... | 2002 | 12045029 |
| changes in whole-tree water relations during ontogeny of pinus flexilis and pinus ponderosa in a high-elevation meadow. | we measured sap flux in pinus ponderosa laws. and pinus flexilis james trees in a high-elevation meadow in northern arizona that has been invaded by conifers over the last 150 years. sap flux and environmental data were collected from july 1 to september 1, 2000, and used to estimate leaf specific transpiration rate (el), canopy conductance (gc) and whole-plant hydraulic conductance (kh). leaf area to sapwood area ratio (la/sa) increased with increasing tree size in p. flexilis, but decreased wi ... | 2002 | 12091149 |
| antifungal activity of the essential oils from some species of the genus pinus. | the chemical composition of the essential oils from the needles of pinus ponderosa (north american pine), p. resinosa (red pine) and p. strobus (eastern white pine) has been determined by gc/ms (fid). the essential oils from p. resinosa and p. ponderosa in comparison to p. strobus have been characterized by the higher content of beta-pinene (42.4%, 45.7% and 7.9% respectively). on the other hand, a-pinene (17.7%) and germacrene d (12.2%) were dominant compounds of p strobus. moreover the essenti ... | 2002 | 12132688 |
| hydraulic redistribution of soil water during summer drought in two contrasting pacific northwest coniferous forests. | the magnitude of hydraulic redistribution of soil water by roots and its impact on soil water balance were estimated by monitoring time courses of soil water status at multiple depths and root sap flow under drought conditions in a dry ponderosa pine (pinus ponderosa dougl. ex laws) ecosystem and in a moist douglas-fir (pseudotsuga menziesii (mirb.) franco) ecosystem. the fate of deuterated water applied to small plots to create a strong horizontal soil water potential gradient was also monitore ... | 2002 | 12414370 |
| ultrastructure of vascular cambial cell cytokinesis in pine seedlings preserved by cryofixation and substitution. | trees depend on the secondary vascular cambium to produce cells for new xylem and phloem. the fusiform cells of this lateral meristem are long and narrow, presenting special challenges for arranging the mitotic spindle and phragmoplast. fusiform cambial cells of pinus ponderosa and pinus contorta were studied by cryofixation and cryosubstitution which preserved ultrastructure and phases of cytokinesis with a resolution not previously attained. membranous structures including the plasma membrane, ... | 2002 | 12417935 |
| effects of co(2) enrichment on growth and root (15)nh(4) (+) uptake rate of loblolly pine and ponderosa pine seedlings. | we examined changes in root growth and (15)nh(4) (+) uptake capacity of loblolly pine (pinus taeda l.) and ponderosa pine (pinus ponderosa douglas. ex laws.) seedlings that were grown in pots in a phytotron at co(2) partial pressures of 35 or 70 pa with nh(4) (+) as the sole n source. kinetics of (15)n-labeled nh(4) (+) uptake were determined in excised roots, whereas total nh(4) (+) uptake and uptake rates were determined in intact root systems following a 48-h labeling of intact seedlings with ... | 1996 | 14871789 |
| trace element concentration in tree-rings biomonitoring centuries of environmental change. | inductively coupled plasma mass spectrometry (icp-ms) was used to examine trace element concentration in tree-rings over three and half centuries to assess macro-trends of environmental change. tree-rings of a 350+ year old mammoth ponderosa pine (pinus ponderosa) were analyzed for element concentration and evaluated versus local and global historical events. the ponderosa pine was located 100 miles south of the canada/usa border and 180 miles east of the pacific ocean, and grew near apple orcha ... | 2002 | 12430645 |
| xylem vulnerability to cavitation in pseudotsuga menziesii and pinus ponderosa from contrasting habitats. | in the rocky mountains, ponderosa pine (pinus ponderosa (ssp.) ponderosa dougl. ex p. laws. & c. laws) often co-occurs with douglas-fir (pseudotsuga menziesii var. glauca (mayr) franco). despite previous reports showing higher shoot vulnerability to water-stress-induced cavitation in ponderosa pine, this species extends into drier habitats than douglas-fir. we examined: (1) whether roots and shoots of ponderosa pine in riparian and slope habitats are more vulnerable to water-stress-induced cavit ... | 2003 | 12511303 |
| reliance on stored water increases with tree size in three species in the pacific northwest. | in tall old forests, limitations to water transport may limit maximum tree height and reduce photosynthesis and carbon sequestration. we evaluated the degree to which tall trees could potentially compensate for hydraulic limitations to water transport by increased use of water stored in xylem. using sap flux measurements in three tree species of the pacific northwest, we showed that reliance on stored water increases with tree size and estimated that use of stored water increases photosynthesis. ... | 2003 | 12566259 |
| isocupressic acid blocks progesterone production from bovine luteal cells. | the needles of ponderosa pine (pinus ponderosa laws.) were reported to induce abortions when fed to late-term pregnant beef cows in north america. an in vivo study of pregnant cows suggested that isocupressic acid (ia) was the main abortifacient isolated from needles and bark of the pine. however, the mechanism of abortifacient activity of ia is not clear yet. in a pregnant cow, the corpus luteum of the ovary helps the maintenance of pregnancy by its progesterone production. this study involved ... | 2002 | 12568280 |
| hydraulic conductivity in roots of ponderosa pine infected with black-stain (leptographium wageneri) or annosus (heterobasidion annosum) root disease. | roots from healthy and diseased mature ponderosa pine, pinus ponderosa laws., trees were excavated from a site near burns, oregon. the diseased trees were infected with black-stain root disease, leptographium wageneri kendrick, or annosus root disease, heterobasidion annosum (fr.) bref., or both. axial hydraulic conductivity of the roots was measured under a positive head pressure of 5 kpa, and the conducting area was stained with safranin dye to determine specific conductivity (k(s)). in diseas ... | 1998 | 12651373 |
| influence of ectomycorrhizal fungal inoculation on growth and root iaa concentrations of transplanted conifers. | we determined whether in vitro plant growth regulator production by mycorrhizal fungi is correlated with conifer seedling growth and root iaa concentrations. container-grown seedlings of interior douglas-fir (pseudotsuga menziesii (mirb.) franco), lodgepole pine (pinus contorta dougl.) and ponderosa pine (pinus ponderosa dougl.) were inoculated at seeding with ectomycorrhizal fungi having a high, moderate or low capacity to produce either iaa or ethylene in vitro. inoculated seedlings were grown ... | 1998 | 12651408 |
| differences in leaf gas exchange and water relations among species and tree sizes in an arizona pine-oak forest. | we compared leaf gas exchange and water potential among the dominant tree species and major size classes of trees in an upland, pine-oak forest in northern arizona. the study included old-growth gambel oak (quercus gambelii nutt.), and sapling, pole, and old-growth ponderosa pines (pinus ponderosa var. scopulorum dougl. ex laws.). old-growth oak had higher predawn leaf water potential (psi(leaf)) than old-growth pine, indicating greater avoidance of soil water stress by oak. old-growth oak had h ... | 2000 | 12651521 |
| photosynthetic adjustment in field-grown ponderosa pine trees after six years of exposure to elevated co(2). | photosynthesis of tree seedlings is generally enhanced during short-term exposure to elevated atmospheric co(2), but longer-term photosynthetic responses are often more variable because they are affected by morphological, biochemical and physiological feedback mechanisms that regulate carbon assimilation to meet sink demand. to examine biochemical and morphological factors that might regulate the long-term photosynthetic response of field-grown trees to elevated co(2), we grew ponderosa pine (pi ... | 1999 | 12651564 |
| evidence that hydraulic conductance limits photosynthesis in old pinus ponderosa trees. | we tested the hypotheses that hydraulic conductance is lower in old (about 250 years old and 30 m tall) compared to young (about 40 years old and 10 m tall) pinus ponderosa dougl. ex laws. trees and that lower hydraulic conductance of old trees limits their photosynthesis. hydraulic conductance at the end of summer 1995, calculated from leaf water potential and leaf gas exchange measurements on one-year-old needles, was 44% lower in old trees compared to young trees growing in a mixed age-class ... | 1999 | 12651579 |
| chloroplastic responses of ponderosa pine (pinus ponderosa) seedlings to ozone exposure. | integrity of chloroplast membranes is essential to photosynthesis. loss of thylakoid membrane integrity has been proposed as a consequence of ozone (o(3)) exposure and therefore may be a mechanistic basis for decreased photosynthetic rates commonly associated with ozone exposure. to investigate this hypothesis, pinus ponderosa seedlings were exposed to ambient air or ozone concentrations maintained at 0.15 or 0.30 microliter l(-1) for 10 h day(-1) for 51 days during their second growing season. ... | 2003 | 12676234 |
| potential for assessing long-term dynamics in soil nitrogen availability from variations in delta15n of tree rings. | numerous researchers have used the isotopic signatures of c, h, and o in tree rings to provide a long-term record of changes in the physiological status, climate, or water-source use of trees. the frequently limiting element n is also found in tree rings, and variation in its isotopic signature may provide insight into long-term changes in soil n availability of a site. however, research has suggested that n is readily translocated among tree ring of different years; such infidelity between the ... | 2003 | 12812252 |
| feeding response of ips paraconfusus to phloem and phloem metabolites of heterobasidion annosum-inoculated ponderosa pine, pinus ponderosa. | in studies of feeding by the bark beetle, ips paraconfusus, two pine stilbenes (pinosylvin and pinosylvin methyl ether), ferulic acid glucoside, and enantiomers of the four most common sugars present in ponderosa pine phloem (sucrose, glucose, fructose, and raffinose) did not stimulate or reduce male feeding when assayed on wet alpha-cellulose with or without stimulatory phloem extractives present. when allowed to feed on wet alpha-cellulose containing sequential extracts (hexane, methanol, and ... | 2003 | 12857030 |
| ozone uptake, water loss and carbon exchange dynamics in annually drought-stressed pinus ponderosa forests: measured trends and parameters for uptake modeling. | this paper describes 3 years of physiological measurements on ponderosa pine (pinus ponderosa dougl. ex laws.) growing along an ozone concentration gradient in the sierra nevada, california, including variables necessary to parameterize, validate and modify photosynthesis and stomatal conductance algorithms used to estimate ozone uptake. at all sites, gas exchange was under tight stomatal control during the growing season. stomatal conductance was strongly correlated with leaf water potential (r ... | 2004 | 14704137 |
| carbon isotopic composition, gas exchange, and growth of three populations of ponderosa pine differing in drought tolerance. | effects of water supply on gas exchange, carbon isotopic composition, and relative growth rate were compared among seedlings from three populations of ponderosa pine (pinus ponderosa dougl. ex laws.) grown in a controlled environment chamber. the three populations were chosen to represent high, moderate and low drought tolerance. there was no indication that drought tolerance was related to high water-use efficiency. populations differed (p < 0.05) in relative growth rate (rgr), but did not diff ... | 1997 | 14759838 |
| nutrient availability alters belowground respiration of ozone-exposed ponderosa pine. | exposure to ozone (o(3)) and changes in soil fertility influence both the metabolism of plant roots and their interaction with rhizosphere organisms. because one indication of altered root metabolism is a change in belowground respiratory activity, we used specially designed measurement chambers to assess the effects of o(3) and nutrient availability on belowground respiratory activity of potted three-year-old ponderosa pine (pinus ponderosa dougl. ex laws.). seedlings were exposed to a factoria ... | 1997 | 14759846 |
| carry-over effects of ozone on root growth and carbohydrate concentrations of ponderosa pine seedlings. | ozone exposure decreases belowground carbon allocation and root growth of plants; however, the extent to which these effects persist and the cumulative impact of ozone stress on plant growth are poorly understood. to evaluate the potential for plant compensation, we followed the progression of ozone effects, with particular emphasis on the development of new roots. ponderosa pine (pinus ponderosa dougl. ex laws.) seedlings were exposed to ozone for 2 years. following removal of the seedlings fro ... | 1997 | 14759890 |
| high temperature and drought stress effects on survival of pinus ponderosa seedlings. | we studied the effects of high temperature and drought on the survival, growth and water relations of seedlings of pinus ponderosa (dougl.) lawson, one of few coniferous tree species that can successfully colonize drought-prone sites with high soil surface temperatures. temperature profiles were measured with 0.07-mm thermocouples in a sparse ponderosa pine forest in northern idaho. the soil surface and the adjacent 5 mm of air reached maximum temperatures exceeding 75 degrees c, well above the ... | 1996 | 14871688 |
| growth and carbon accumulation in root systems of pinus taeda and pinus ponderosa seedlings as affected by varying co(2), temperature and nitrogen. | it has been hypothesized that increasing atmospheric co(2) concentration enhances accumulation of carbon in fine roots, thereby altering soil carbon dynamics and nutrient cycling. to evaluate possible changes to belowground pools of carbon and nitrogen in response to elevated co(2), an early and a late successional species of pine (pinus taeda l. and pinus ponderosa dougl. ex laws, respectively) were grown from seed for 160 days in a 35 or 70 pa co(2) partial pressure at low or high temperature ... | 1996 | 14871701 |
| direct and indirect effects of elevated co(2) on whole-shoot respiration in ponderosa pine seedlings. | we determined the short-term direct and long-term indirect effects of co(2) on apparent dark respiration (co(2) efflux in the dark) in ponderosa pine (pinus ponderosa dougl. ex laws.) seedlings grown in 35 or 70 pa co(2) partial pressure for 163 days in naturally lit, controlled-environment chambers. two soil n treatments (7 and 107 ppm total n, low-n and high-n treatments, respectively) were imposed by watering half the plants every 2 weeks with 15/15/18 fertilizer (n,p,k) and the other half wi ... | 1996 | 14871745 |
| stem maintenance and construction respiration in pinus ponderosa grown in different concentrations of atmospheric co(2). | to determine whether long-term growth in enriched co(2) atmospheres changes the woody tissue respiration component of aboveground carbon budgets, we measured woody tissue respiration of stems of 3-year-old ponderosa pine (pinus ponderosa laws.) grown in ambient (350 ppm) or twice ambient (700 ppm) atmospheric co(2) concentrations in open-top field chambers located in placerville, ca. total respiration rate was measured by gas exchange, and construction respiration was calculated from the constru ... | 1996 | 14871755 |
| to live fast or not: growth, vigor and longevity of old-growth ponderosa pine and lodgepole pine trees. | old trees of ponderosa pine (pinus ponderosa dougl. ex laws.) and lodgepole pine (pinus contorta var. latifolia engelm.) were studied to determine volume growth patterns in relation to leaf area. ponderosa pine trees varied in age from 166 to 432 years and were about 77 cm in diameter; lodgepole pine trees varied in age from 250 to 296 years and were about 31 cm in diameter. with the exception of several ponderosa pine trees less than 200 years old, trees of both species had flattened tops, heav ... | 1996 | 14871757 |
| effects of elevated co(2) and nitrogen on the synchrony of shoot and root growth in ponderosa pine. | we monitored effects of elevated co(2) and n fertilization on shoot and fine root growth of pinus ponderosa dougl. ex p. laws. and c. laws. grown in native soil in open-top field-exposure chambers at placerville, ca, over a 2-year period. the experimental design was a replicated 3 x 3 factorial with the center treatment missing; plants were exposed to ambient (~365 micro mol mol(-1)) air or ambient air plus either 175 or 350 micro mol mol(-1) co(2) in combination with one of three rates of n add ... | 1996 | 14871783 |
| seasonal variation of gas exchange and pigmentation in branches of three grafted clones of mature ponderosa pine exposed to ozone and acid rain. | gas exchange and pigmentation responses of mature ponderosa pine (pinus ponderosa laws.) branches to ozone and acid rain exposure were investigated using three grafted clones growing in a managed seed orchard. exposure of one-year-old foliage to twice ambient ozone (2 x amb) resulted in significant decreases in net photosynthesis (pn), stomatal conductance (gsw) and pigmentation relative to charcoal-filtered (cf) and ambient (amb) ozone treatments. ozone effects on gas exchange and pigmentation ... | 1997 | 15093363 |
| accentuation of gas exchange gradients in flushes of ponderosa pine exposed to ozone. | two-year-old ponderosa pine seedlings (pinus ponderosa laws.) were exposed to episodic o(3) concentrations in open-top chambers for two consecutive growing seasons (june through september of 1990 and 1991). near the end of the second season of o(3) exposure, gas exchange was measured on needles of surviving flushes at saturating co(2) and photosynthetic photon flux density (ppfd). both photosynthetic capacity (a(sat)) and stomatal conductance to water vapor (g(wv)) declined linearly with needle ... | 1995 | 14965974 |
| offsetting changes in biomass allocation and photosynthesis in ponderosa pine (pinus ponderosa) in response to climate change. | we examined the effect of climate on aboveground biomass allocation of ponderosa pine (pinus ponderosa) by measuring trees in disjunct forest stands growing on the same substrate at high-elevation montane sites and low-elevation desert sites. climatic differences between the sites were comparable to the difference between present and future climates of interior north america that is expected to result from a doubling of atmospheric co(2) concentration. relative to the montane populations, the de ... | 1994 | 14967639 |
| carbon allocation, gas exchange, and needle morphology of pinus ponderosa genotypes known to differ in growth and survival under imposed drought. | seedlings from 27 open-pollinated families of ponderosa pine representing nine geographically diverse origins were screened for drought tolerance based on survival and growth under imposed drought. seedlings that had been preconditioned to drought survived 14 days longer than seedlings that had been well watered before being subjected to drought. seed sources varied in their ability to survive drought and this variation was accentuated by drought preconditioning. seedlings from a south dakota so ... | 1994 | 14967656 |
| converging patterns of uptake and hydraulic redistribution of soil water in contrasting woody vegetation types. | we used concurrent measurements of soil water content and soil water potential (psi(soil)) to assess the effects of psi(soil) on uptake and hydraulic redistribution (hr) of soil water by roots during seasonal drought cycles at six sites characterized by differences in the types and amounts of woody vegetation and in climate. the six sites included a semi-arid old-growth ponderosa pine (pinus ponderosa dougl. ex p. laws & c. laws) forest, a moist old-growth douglas-fir (pseudotsuga menziesii (mir ... | 2004 | 15172842 |
| analysis of the relationships among o(3) uptake, conductance, and photosynthesis in needles of pinus ponderosa. | we studied the effects of o(3) uptake on conductance (g(wv)) and photosynthesis (a) in needles of ponderosa pine (pinus ponderosa laws.) seedlings exposed for 70 days to one of three o(3) regimes-low-o(3) (0.1 micro mol mol(-1) daily peak), high-o(3) (0.2 micro mol mol(-1) daily peak), and low/high-o(3) (alternating 2 days low-o(3) and 2 days high-o(3)). seedlings exposed to charcoal-filtered air served as controls. total o(3) exposures, expressed as ppm-h (the sum of the average hourly concentr ... | 1993 | 14969893 |
| nutritional ecology of the formosan subterranean termite (isoptera: rhinotermitidae): growth and survival of incipient colonies feeding on preferred wood species. | the wood of 11 plant species was evaluated as a food source significantly impacting the growth and survival of incipient colonies of the formosan subterranean termite, coptotermes formosanus shiraki (isoptera: rhinotermitidae). colonies of c. formosanus feeding on pecan, carya illinoensis (wangenh.), and red gum, liquidambar styraciflua l., produced significantly more progeny than colonies feeding on other wood species tested. progeny of colonies feeding on pecan and american ash, fraxinus ameri ... | 2003 | 12650352 |
| regulation of ponderosa pine foliar physiology and insect resistance mechanisms by basal area treatments. | we compared foliar physiology and several measures of tree resistance to insect attack among ponderosa pine (pinus ponderosa var. scopulorum engelm.) trees growing in thinned stands. measurements were made in a second-growth ponderosa pine forest in northern arizona where the basal area treatments (6.9, 18.4, 27.6, 78.2 m(2) ha(-1)) have been experimentally maintained by frequent thinnings for 32 years before our measurements began in 1994. most of the physiological characteristics measured were ... | 1998 | 12651362 |
| composition of gum turpentines of pines: a report on pinus ponderosa, p. banksiana, p. canariensis, and p. washoensis. | | 1950 | 15421914 |
| control of shoot elongation in ponderosa pine: relative roles of apical and axillary meristems. | buds of ponderosa pine (pinus ponderosa var. scopulorum engelm.) from which the shoot apical meristems had been surgically removed elongated normally but did not form new terminal buds. shoot, stem unit and needle growth were similar to those of controls. removal of needle fascicles from buds starting to elongate inhibited growth, whether or not the shoot apical meristem had been removed. the length of completely defoliated shoots increased by 8.3%, the length of shoots defoliated on the upper h ... | 1988 | 14972813 |
| chlorophyll and carotenoid concentrations in two varieties of pinus ponderosa seedlings subjected to long-term elevated carbon dioxide. | two varieties of ponderosa pine (pinus ponderosa dougl. var. scopulorum (rocky mountain variety) and p. ponderosa var. ponderosa (sierran variety)) seedlings were subjected to elevated atmospheric co(2) for two and a half years. the co(2) concentrations were ambient, ambient + 75 microl l(-1), ambient + 150 microl l(-1) and ambient + 300 microl l(-1), or approximately 350, 425, 500 and 650 microl l(-1) co(2). after one and a half years of exposure to elevated co(2) and until the end of the study ... | 1988 | 14972829 |
| simulating the effects of climatic variation on stem carbon accumulation of a ponderosa pine stand: comparison with annual growth increment data. | simulation models of ecosystem processes may be necessary to separate the long-term effects of climate change on forest productivity from the effects of year-to-year variations in climate. the objective of this study was to compare simulated annual stem growth with measured annual stem growth from 1930 to 1982 for a uniform stand of ponderosa pine (pinus ponderosa dougl.) in montana, usa. the model, forest-bgc, was used to simulate growth assuming leaf area index (lai) was either constant or inc ... | 1991 | 14972862 |
| fall lifting and long-term freezer storage of ponderosa pine seedlings: effects on post-storage leaf water potential, stomatal conductance, and root growth potential. | post-storage water relations, stomatal conductance, and root growth potential were examined in ponderosa pine (pinus ponderosa dougl. ex laws.) seedlings from high- and low-elevation seed sources that had been lifted either in october or november and freezer stored, or in march, and then grown hydroponically in a greenhouse for 31 days. seedlings lifted in october had poor root initiation (< 17 new roots per seedling), low predawn leaf water potentials (< -1.5 mpa), and low stomatal conductance ... | 1991 | 14972882 |
| influence of drought stress and low irradiance on plant water relations and structural constituents in needles of pinus ponderosa seedlings. | the influence of low light on tolerance to prolonged drought was tested on unshaded and shaded seedlings of ponderosa pine (pinus ponderosa var. scopulorum dougl. ex laws.). unshaded seedlings of p. ponderosa var. ponderosa were also drought stressed to compare varietal responses to drought. the maximum irradiance received by shaded seedlings was 10% of full light. seedlings were progressively drought stressed until predawn water potentials (psi(x)) were -5.0 mpa. relative water content (rwc) an ... | 1991 | 14972888 |
| comparison of three cold hardiness tests for conifer seedlings. | greenhouse-cultured, container-grown ponderosa pine (pinus ponderosa var. scopulorum engelm.), interior douglas-fir (pseudotsuga menziesii var. glauca (beissn.) franco), and engelmann spruce (picea engelmannii (parry) engelm.) were cold acclimated and deacclimated in growth chambers over 19 weeks. cold hardiness was measured weekly by a whole-plant freeze test and by two quick tissue tests: freeze-induced electrolyte leakage of needles, and differential thermal analysis of buds. the whole-plant ... | 1990 | 14972928 |
| relationships among cold hardiness, root growth potential and bud dormancy in three conifers. | greenhouse-cultured, container-grown ponderosa pine (pinus ponderosa var. scopulorum engelm.), interior douglas-fir (pseudotsuga menziesii var. glauca (beissn.) franco) and engelmann spruce (picea engelmannii (parry) engelm.) were cold acclimated and deacclimated in growth chambers over 19 weeks. stem cold hardiness, total new root length at 14 days and days to bud break were measured weekly. relationships among cold hardiness, root growth potential (rgp) and bud dormancy suggest that cold hardi ... | 1989 | 14972975 |
| growth and physiological responses of pinus ponderosa dougl ex p. laws. to long-term elevated co(2) concentrations. | seven-year-old ponderosa pine (pinus ponderosa dougl. ex p. laws.) saplings and one- and two-year-old ponderosa pine seedlings of a sierra nevada and a rocky mountain seed source, respectively, were exposed to co(2)-enriched atmospheres in an outdoor open-top chamber facility for 2.5 years. seedling growth (main stem diameter, height, volume) increased with increasing co(2) concentration, though the two populations exhibited different patterns of response. by the beginning of the last growth sea ... | 1986 | 14975858 |
| restoration thinning and influence of tree size and leaf area to sapwood area ratio on water relations of pinus ponderosa. | ponderosa pine (pinus ponderosa dougl. ex p. laws) forest stand density has increased significantly over the last century (covington et al. 1997). to understand the effect of increased intraspecific competition, tree size (height and diameter at breast height (dbh)) and leaf area to sapwood area ratio (a(l):a(s)) on water relations, we compared hydraulic conductance from soil to leaf (kl) and transpiration per unit leaf area (q(l)) of ponderosa pine trees in an unthinned plot to trees in a thinn ... | 2006 | 16414928 |
| a comparison of three approaches to modeling leaf gas exchange in annually drought-stressed ponderosa pine forests. | we tested, compared and modified three models of stomatal conductance at the leaf level in a forest ecosystem where drought stress is a major factor controlling forest productivity. the models were tested against 2 years (1999 and 2000) of leaf-level measurements on ponderosa pine (pinus ponderosa dougl. ex laws.) growing in the mediterranean climate of california, usa. the ball, woodrow and berry (1987) (bwb) model was modified to account for soil water stress. among the models, results of the ... | 2004 | 14996657 |
| efects of the pine needle abortifacient, isocupressic acid, on bovine oocyte maturation and preimplantation embryo development. | isocupressic acid (ica) [15-hydroxylabda-8 (17), 13e-dien-19-oic acid], a labdane diterpene acid, isolated from ponderosa pine (pinus ponderosa), lodgepole pine (pinus contorta), common juniper (juniperus communis) and monterey cypress (cupressus macrocarpa), induces abortion in pregnant cows when ingested primarily during the last trimester. the objective of this study was to investigate the effects of isocupressic acid on bovine oocyte maturation (in vitro maturation (ivm)-experiment i) and pr ... | 2004 | 14998650 |
| nitrate reductase activity as an indicator of ponderosa pine response to atmospheric nitrogen deposition in the san bernardino mountains. | determinations of nitrate reductase (nr) activity in ponderosa pine (pinus ponderosa dougl. ex. laws.) needles were performed during summer 1994 in two areas (consisting of six different sites) with different nitrogen (n) deposition levels in the san bernardino mountains, southern california. nitrate reductase activity was used as an integrative indicator of atmospheric nitrogen deposition to pine trees (direct uptake of n species from the atmosphere and n transported from the soil). deposition ... | 1996 | 15091353 |
| effects of simulated acid rain and ozone on foliar chemistry of field-grown pinus ponderosa seedlings and mature trees. | we investigated the additive and interactive effects of simulated acid rain and elevated ozone on c and n contents, and the c:n ratio of one-year-old and current-year foliage of field-grown mature trees and their half-sib seedlings of a stress tolerant genotype of ponderosa pine. acid rain levels (ph 5.1 and 3.0) were applied weekly to foliage only (no soil acidification or n addition), from january to april, 1992. plants were exposed to two ozone levels (ambient and twice-ambient) during the da ... | 1996 | 15091457 |