摘要:

Clones encoding polyubiquitin proteins were isolated from a cDNA library derived fromPinussabinianaphloem tissue. Two different polyubiquitin clones were sequenced. The amino acid sequences of the clones were compared with angiosperm polyubiquitin sequences and with corresponding sequences reported for animal, fungal, and protist polyubiquitins. A computer-aided analysis showed (i) that pine and angiosperm polyubiquitin amino acid sequences correspond perfectly, (ii) that plant polyubiquitins differ from animal polyubiquitins by three amino acids, and (iii) that fungal and protist polyubiquitins are variable, differing by one to eight amino acids from higher organisms. The expression of ubiquitin was studied in bark, cone, needle, phloem, root, and xylem tissues of pine by Northern blot analysis. In all of these tissues, transcripts of about 1000 base pairs were observed. A minor species of 1200 base pairs was seen in longer exposures of autoradiograms. Ubiquitin transcripts were more abundant (in relationship to total RNA) in phloem, cones, and roots than in bark, needles, or xylem.

ISSN:0045-5067    

DOI:10.1139/x95-001

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

We used sand culture to examine the effects of aluminum (Al3+) on gas exchange and growth in 1+0PicearubensSarg. seedlings. Growth solutions were prepared to match the elemental concentrations of the soil solutions in a decliningAbiesbalsamea(L.) Mill.–P.rubensstand. In our first experiment, we used a four-way factorial design to examine the interactions between Al, pH, nutrients, and CO2. All plants were nitrogen deficient. Photosynthetic rate and instantaneous water-use efficiency both declined at 250 μmol•L−1Al, as did the root/shoot ratio of the seedlings. Plant weight, however, was not significantly affected by the 10-fold increase in Al solution concentration. These results were robust across a range of experimental conditions, suggesting that other aspects of soil acidification, such as NO3fertilization in N deficient soils, could counteract the toxic effects of Al. In a second experiment, we examined the effects of subtoxic concentrations of Al at two levels of nutrient cation availability. Unlike in a previous study, cation fertilization affected neither gas exchange nor growth. While the decreases in root/shoot ratio and growth were expected at 250 μmol•L−1Al, the peak in growth rates for intermediate concentrations of Al (25–100 μmol•L−1) was not. The latter result was interpreted in light of the positive effects that low concentrations of Al are known to have on other species.

ISSN:0045-5067    

DOI:10.1139/x95-002

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

One-year-old seedlings of western red cedar (ThujapiicataDonn ex D.Don) and Douglas-fir (Pseudotsugamenziesii(Mirb.) Franco) were grown for one season in five nutrient treatments with nitrogen (N) supplied in solution at rates of 20, 100, or 250 mg•L−1and phosphorus (P) supplied at rates of 4, 20, or 60 mg•L−1. Growth, onset of dormancy, frost hardiness on six dates, and foliar nutrient concentrations in autumn and spring were measured. Midwinter rates of net photosynthesis and transpiration were measured at air temperatures of 4, 7, and 11 °C in seedlings from all nutrient treatments. Recovery of net photosynthesis and transpiration in whole seedlings from the three N treatments was assessed at intervals for 28 days after the seedlings were frozen to −5, −15, and −25°C. Foliar N content differed significantly among nutrient treatments and was positively correlated with supply. Mitotic activity ceased earliest in plants with low N supply. Douglas-fir seedlings in the low-N treatment also ceased height growth earliest. These differences in growth had no significant correlation with frost hardiness. No consistent differences in frost hardiness among nutrient treatments were observed. Higher rates of N and P supply resulted in higher rates of winter net photosynthesis. Net photosynthesis was reduced dramatically by night frost, with greater damage occurring at lower temperatures. Net photosynthesis recovery occurred most quickly in seedlings with the midrate of N and P supply.

ISSN:0045-5067    

DOI:10.1139/x95-003

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The relationships between site index and measures of soil, understory vegetation, and foliar nutrients were examined using data from 102 white spruce (Piceaglauca(Moench) Voss) stands in the Sub-boreal Spruce zone of British Columbia. Compared with soil physical properties (adjusted.R2 = 0.54), soil nutrient properties (adjusted.R2 = 0.29) were poor predictors of white spruce site index. The best soil model, using depth of major rooting zone, total nitrogen, and slope as predictors, explained 60% of the total variance in site index. The best understory vegetation model, using frequencies of soil-moisture and nitrogen indicator species groups as predictors, explained 53% of the total variance in site index. The best foliar nutrient model, using foliar phosphorus and sulphur as predictors, explained 64% of the total variance in site index. Adding variables from understory vegetation, foliar nutrients, or both into the best soil model significantly improved site index prediction. The resultant models explained up to 83% of the total variance in site index. When stands were stratified according to groundwater influence, regression models developed for three delineated strata were significantly improved compared with unstratified models. Based on practical consideration, four regression models were considered for predicting white spruce site index. Independent testing indicated that the stratified model, which used only soil variables as predictors, predicted white spruce site index with 79% of the estimate errors within 2 m in the study area.

ISSN:0045-5067    

DOI:10.1139/x95-004

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Measurements of the stable carbon isotope composition of leaf tissue were made onPiceamariana(Mill.) B.S.P trees from four full-sib families grown on three different field sites at the Petawawa National Forestry Institute, Ontario, Canada. The four families chosen exhibited genetic variation for growth characteristics. Genetic variation was also observed for carbon isotopic discrimination (Δ) among the families ofP.mariana. In addition, a strong correlation occurred between Δ values measured on trees in 1991 and 1992, two years that had very different precipitation and temperature conditions during the growing season, indicating that the ranking of individual trees remained almost constant between years. A strong, negative correlation was observed between average carbon isotope discrimination and average tree height for the four families on the driest, least productive site, as was expected based on leaf photosynthetic characteristics. There was no significant correlation, however, between Δ values and growth on the other two study sites, where productivity was higher.

ISSN:0045-5067    

DOI:10.1139/x95-005

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Three conifer species grown in plantations in the southeastern Adirondack Mountains of New York were chosen to model tree growth. Annual growth of trees was decomposed into several components that reflect various intrinsic or extrinsic factors. Growth signals indicative of climatic effects were used to construct growth-climate models using both multivariate regression analysis and Kalman filter methods. Two growth models were used to simulate tree growth response to future climate change projected by GCMs. The consistent results of both models indicate that different conifer species have individualistic growth responses to future climatic change. The response behaviors of trees are affected greatly by local stand conditions and species tolerance to drought.

ISSN:0045-5067    

DOI:10.1139/x95-006

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

A nonlinear model that yields logical predictions for tree crown ratio is presented. The model is based on data from permanent experimental plots located in even-aged Scots pine (PinussylvestrisL.) stands in southern and central Finland. Regressor variables in the model are stand dominant height, stand basal area, tree diameter, and tree height. The effect of thinning on tree crown ratio is modelled by incorporating a thinning response variable into the model. Thinning effect is dependent on thinning intensity and time elapsed from thinning, the latter of which is represented by the difference between current stand dominant height and dominant height at the time of thinning.

ISSN:0045-5067    

DOI:10.1139/x95-007

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Two dosages of Teione II-B (1,3-dichloropropene) at 3.4 and 6.7 mL/kg of stump and root biomass were tested to determine the efficacy in reducingPhellinusweirii(Murr.) Gilb. inoculum in infected Douglas-fir,Pseudotsugamenziesii(Mirb.) Franco, stumps. After 21 months, both doses of Teione II-B proved equally effective and significantly (p < 0.05) reduced residualP.weiriimycelium in infected roots. Fumigation reduced residual endotrophicP.weiriiin the large-diameter root classes nearest the stump, but survival of the fungus was less affected with increasing distance from the stump and in the smaller root diameter classes. Treated stumps also had significantly (p < 0.05) fewer roots with ectotrophic mycelium than untreated stumps. Four weeks after application, soil samples taken near treated stumps revealed no evidence of the fumigant. These findings suggest that application of Teione II-B could be used as an effective control measure forP.weirii.

ISSN:0045-5067    

DOI:10.1139/x95-008

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The factors determining individual tree growth response are examined during the 4 years following thinning in experiments in even-aged, 8- or 12-year-old regrowthEucalyptusregnansF. Muell. forest at two sites in southern Australia. At one site, a vigorous understorey dominated by a sedge developed after the thinning. At that site, light-use efficiency by the trees was unaffected by thinning and the aboveground biomass production by the trees in the thinned stand was substantially less than that in the unthinned stand. At the other site, little understorey developed, light-use efficiency by trees in the thinned stand was greater than that in the unthinned stand, and aboveground biomass production was unaffected by thinning even though the leaf weight of the thinned stand was far below that of the unthinned stand. Where the understorey developed, it was concluded that it competed successfully with the trees for water, thereby reducing production in the thinned stand when compared with the unthinned stand. The individual tree growth response that occurred in the thinned stand at that site appeared to be due soley to the extra light available to individual trees following the canopy opening. Where the understorey did not develop, it was concluded that individual tree growth response was due not only to the extra light available to individual trees but also to the increased availability of belowground resources, most probably soil water. Application of a pre-existing stand growth model suggested that at that site the tendency for increased growth resulting from extra water availability in the thinned stand was just balanced by decreased growth due to lower radiation absorption by the reduced canopy, so that net production was unaffected by thinning.

ISSN:0045-5067    

DOI:10.1139/x95-009

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Total P was monitored at Huntington Forest in the Adirondack Mountains of New York from June 1986 to May 1987. Total P in precipitation from an adjacent open site was compared with throughfall, stemflow, and soil solutions collected from a hardwood stand dominated by American beech (FagusgrandifoliaEhrh.) and sugar maple (AcersaccharumMarsh.). Total P concentrations in bulk precipitation were very similar throughout the year (4.95 μmol•L−1in rain versus 4.93 μmol•L−1in snow). Total P concentration was lower in throughfall than in bulk precipitation, and P in growing season bulk throughfall (1.79 μmol•L−1) was greater than that in the dormant season (1.00 μmol•L−1). Total P concentrations in both throughfall and stemflow were higher under beech than maple. Phosphorus concentrations in soil solutions decreased as water passed through the soil profile. Phosphorus was tightly retained in this ecosystem except for a small loss via drainage water during spring snowmelt.

ISSN:0045-5067    

DOI:10.1139/x95-010

出版商:NRC Research Press    

年代:1995

数据来源: NRC