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1.
《Scandinavian Journal of Forest Research》2012,27(6):501-510
Scots pine ( Pinus sylvestris L.) and Norway spruce [ Picea abies (L.) Karst.] seedlings were exposed to high phosphorus (HP) or low phosphorus (LP) availability for one growing season in the open field, and to combined P availability and elevated ozone (O 3 ) concentrations (0, 55, 110 and 210 ppb for Scots pine and 0, 40, 75 and 150 ppb for Norway spruce, respectively) for 28 days in controlled laboratory chambers. Compared with HP, the LP treatment reduced Scots pine current-year (C) shoot and root dry masses and Norway spruce total dry mass, whereas the highest O 3 concentrations increased the magnesium concentration of Scots pine C needles and P concentrations of the C needles of both tree species. Chlorophyll a, a+b and carotenoid concentrations of Scots pine C needles were significantly higher in the LP treatment compared with HP under the highest O 3 concentration (210 ppb). In the mesophyll tissue of C needles of both tree species, LP treatment increased the size of mitochondria and elevated O 3 -induced granulation of chloroplast stroma and disintegration of cytoplasm. Exposure to elevated O 3 concentrations increased swelling of chloroplast thylakoids and reduced the amount of vacuolar tannin in the LP Scots pine C needles. The results suggest disturbances in needle photosynthetic machinery due to acute exposure to the combination of elevated O 3 and low P availability. However, clear additive effects were found only in needle P concentrations < 1 mg g -1 in short-term O 3 exposure. 相似文献
2.
We previously traced 10B-enriched boric acid from shoots to roots to demonstrate the translocation of boron (B) in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings. To gain a more detailed understanding of B translocation, we sought: (1) to demonstrate B retranslocation directly, by showing that foliar-applied 10B is located in the new growth after dormancy; and (2) to assess whether shoot-applied B affects growth in the long term. We applied 10B-enriched boric acid to needles of Scots pine and Norway spruce seedlings. After a dormancy period and 9 weeks of growth, small but significant increases in the 10B isotope were found in the new stem and needles of both species. In Scots pine, the total B concentration of the new stem was also increased. Both species contained polyols, particularly pinitol and inositol. Boron-polyol complexes may provide a mechanism for mobilizing B in these species. To determine the long-term effects of applied B, seedlings were grown for two growing seasons after the application of 10B to shoots. In Norway spruce, the proportion of 10B in the root systems and current needles of the harvest year was slightly higher than in the controls, and in Scots pine root systems, marginally so. The B treatment had no effect on growth of Norway spruce seedlings. In Scots pine seedlings, the B treatment caused a 33% increase in total dry mass and significantly increased the number of side branches. 相似文献
3.
Sixteen 20-year-old Scots pine (Pinus sylvestris L.) trees growing in the field were enclosed in environment-controlled chambers that for 4 years maintained: (1) ambient conditions (CON); (2) elevated atmospheric carbon dioxide concentration [CO2] (ambient + 350 micromol mol-1; EC); (3) elevated temperature (ambient + 2-3 degrees C; ET); or (4) elevated [CO2] and temperature (EC+ET). Dark respiration rate, specific leaf area (SLA) and the concentrations of starch and soluble sugars in needles were measured in the fourth year. Respiration rates, on both an area and a mass basis, and SLA decreased in EC relative to CON, but increased in ET and EC+ET, regardless of needle age class. Starch and soluble sugar concentrations for a given needle age class increased in EC, but decreased slightly in ET and EC+ET. Respiration rates and SLA were highest in current-year needles in all treatments, whereas starch and soluble sugar concentrations were highest in 1-year-old needles. Relative to that of older needles, respiration of current-year needles was inhibited less by EC, but increased in response to ET and EC+ET. All treatments enhanced the difference in respiration between current-year and older needles relative to that in CON. Age had a greater effect on needle respiration than any of the treatments. There were no differences in carbohydrate concentration or SLA between needle age classes in response to any treatment. Relative to CON, the temperature coefficient (Q10) of respiration increased slightly in EC, regardless of age, but declined significantly in ET and EC+ET, indicating acclimation of respiration to temperature. 相似文献
4.
There is abundant evidence that evergreen conifers living at high elevations or at high latitudes have longer-lived needles than trees of the same species living elsewhere. This pattern is likely caused by the influence of low temperature in combination with related factors such as a short growing season and low nutrient availability. Because it is not known to what degree such patterns result from phenotypic versus genotypic variation, we evaluated needle longevity for common-garden-grown lowland populations of European Scots pine (Pinus sylvestris L.) of wide latitudinal origin and Norway spruce (Picea abies L.) of wide elevational origin. Nine-year-old trees of 16 Scots pine populations ranging in origin from 47 degrees to 60 degrees N were studied in Kórnik, Poland (52 degrees N) and 18-year-old trees of 18 Norway spruce populations ranging in origin from 670 to 1235 m elevation in southwestern Poland were studied near Morawina, Poland (51 degrees N, 180 m elevation). There was no tendency in either species for populations from northern or high elevation origins to retain needles longer than other populations. All of the Scots pine populations had between 2.5 to 3.0 needle age cohorts and all of the Norway spruce populations had between 6.4 and 7.2 needle age cohorts. Thus, extended needle retention in Scots pine and Norway spruce populations in low-temperature habitats at high elevations and high latitudes appears to be largely an environmentally regulated phenotypic acclimation. 相似文献
5.
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
6.
Growth and gas exchange characteristics were studied in pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) seedlings grown in hydroponic culture in the presence of N (50 mg l(-1)) and transferred at the start of their second growing season to tap water at 5, 8, 12, 16 or 20 degrees C (air temperature between 18-20 degrees C) for 3 weeks (pine) or 5 weeks (spruce). Root growth of both species was completely inhibited at root temperatures of 5 and 8 degrees C, but increased almost exponentially as root temperature increased. Shoot growth was maximal at 12 degrees C in both pine and spruce and decreased at low root temperatures. In both species, CO(2) uptake was decreased at low root temperatures and appeared to be influenced by the pattern of nitrogen retranslocation. In pine seedlings, as root temperature increased, an increasing proportion of the total nitrogen pool was retranslocated to the new shoot, whereas in spruce seedlings nitrogen was retranslocated to the roots. Differences in the retranslocation of nitrogen in the two species were reflected in the amount of soluble protein in needles, which at the end of the experiment increased with increasing root temperature in pine, but decreased in spruce. Our data suggest that in spruce, but not pine, CO(2) uptake was limited by the amount of Rubisco. 相似文献
7.
Juurola E 《Tree physiology》2003,23(2):85-95
Acclimation of photosynthesis to increasing atmospheric carbon dioxide concentration ([CO2]; 350 to 2,000 micromol mol-1) was followed in silver birch (Betula pendula Roth.) and Scots pine (Pinus sylvestris L.) seedlings for two years. Chlorophyll fluorescence and concentrations of Rubisco, chlorophyll, total soluble protein and nitrogen were monitored together with steady-state gas exchange at three CO2 concentrations (ambient [CO2] (345 +/- 20 micromol mol-1), the growth [CO2] and 1950 +/- 55 micromol mol-1). Rubisco and chlorophyll concentrations decreased in birch and Scots pine with increasing growth [CO2]. A nonlinear response was recorded for Rubisco and chlorophyll concentrations in birch, which was correlated with a significant decrease in specific leaf area. Nitrogen concentration decreased in birch leaves, but was unchanged in Scots pine needles. The species differed substantially in their steady-state CO2 exchange response to increasing growth [CO2]. The principal effect in birch was a significant nonlinear decrease in the steady-state gas exchange rate at the ambient [CO2], whereas in Scots pine the main effect was a significant increase in the steady-state gas exchange rate at the growth [CO2]. 相似文献
8.
Stem respiration in 20-year-old Scots pine (Pinus sylvestris L.) trees was examined following 5 years of exposure to ambient conditions (CON), elevated atmospheric carbon dioxide concentration ([CO2]) (ambient + 350 micromol mol(-1), (EC)), elevated temperature (ambient + 2-6 degrees C, (ET)) or a combination of elevated [CO2] and elevated temperature (ECT). Stem respiration varied seasonally regardless of the treatment and displayed a similar trend to temperature, with maximum rates occurring around Day 190 in summer and minimum rates in winter. Respiration normalized to 15 degrees C (R15) was higher in the growing season than in the non-growing season, whereas the temperature coefficient (Q10) was lower in the growing season. Annually averaged R15 was 0.36, 0.43, 0.40 and 0.44 micromol m(-2) s(-1) under CON, EC, ET and ECT conditions, respectively, whereas the corresponding values for total stem respiration were 6.55, 7.69, 7.50 and 7.90 mol m(-2) year(-1). The EC, ET and ECT treatments increased R15 by 18, 11 and 22%, respectively, relative to CON, and increased the modeled annual total stem respiration by 18, 15 and 21%. The increase in modeled annual stem respiration under EC and ECT conditions was caused mainly by higher maintenance respiration (22 and 25%, respectively, whereas the increase in growth respiration was 9 and 12%). Growth respiration was unaltered by ET. The treatments did not significantly affect the respiratory response to stem temperature; the mean Q10 value was 2.04, 2.10, 1.99 and 2.12 in the CON, EC, ET and ECT treatments, respectively. It is suggested that the increase in stem respiration was partly a result of the increased growth rate. We conclude that elevated [CO2] increased the maintenance component of respiration more than the growth component. 相似文献
9.
《Forest Ecology and Management》1996,88(3):227-235
The nature of interference of bracken with Scots pine and Norway spruce seedling establishment was considered in three field experiments. In a seeding experiment, it was found that Scots pine germination was highest on exposed mineral soil and lowest when intact bracken litter and humus were present, suggesting adverse effects of litter and humus on pine regeneration probably due to phytotoxicity. In a second experiment, smothering by bracken caused high mortality of Scots pine seedlings while Norway spruce seedlings were relatively unaffected. Mortality for both Scots pine and Norway spruce seedlings was low when planted in a adjacent Scots pine-bilberry stand with no bracken. Annual shoot growth of Norway spruce was higher in bracken than in Scots pine-bilberry vegetation while no differences in shoot growth between these two vegetation types occurred for Scots pine. In a third experiment, activated carbon was added to the ground under Norway spruce seedlings planted in bracken to adsorb possible phytotoxic compounds released by bracken. The addition of carbon had no effect on seedling mortality or growth rate, indicating that the seedlings were not susceptible to allelochemicals released by bracken. Since large Norway spruce seedlings were relatively unaffected by bracken interference in this study, artificial regeneration with containerized Norway spruce seedlings is suggested to achieve an acceptable conifer tree establishment on clear-cuts invaded by bracken. 相似文献
10.
Kilpeläinen A Peltola H Ryyppö A Sauvala K Laitinen K Kellomäki S 《Tree physiology》2003,23(13):889-897
Impacts of elevated temperature and carbon dioxide concentration ([CO2]) on wood properties of 15-year-old Scots pines (Pinus sylvestris L.) grown under conditions of low nitrogen supply were investigated in open-top chambers. The treatments consisted of (i) ambient temperature and ambient [CO2] (AT+AC), (ii) ambient temperature and elevated [CO2] (AT+EC), (iii) elevated temperature and ambient [CO2] (ET+AC) and (iv) elevated temperature and elevated [CO2] (ET+EC). Wood properties analyzed for the years 1992-1994 included ring width, early- and latewood width and their proportions, intra-ring wood density (minimum, maximum and mean, as well as early- and latewood densities), mean fiber length and chemical composition of the wood (cellulose, hemicellulose, lignin and acetone extractive concentration). Absolute radial growth over the 3-year period was 54% greater in AT+EC trees and 30 and 25% greater in ET+AC and ET+EC trees, respectively, than in AT+AC trees. Neither elevated temperature nor elevated [CO2] had a statistically significant effect on ring width, early- and latewood widths or their proportions. Both latewood density and maximum intra-ring density were increased by elevated [CO2], whereas fiber length was increased by elevated temperature. Hemicellulose concentration decreased and lignin concentration increased significantly in response to elevated temperature. There were no statistically significant interaction effects of elevated temperature and elevated [CO2] on the wood properties, except on earlywood density. 相似文献
11.
We investigated the impacts of elevated temperature and carbon dioxide concentration ([CO2]) on diameter growth of Scots pine (Pinus sylvestris L.), aged about 20 years, grown with a low nitrogen supply in closed chambers at (i) ambient temperature and [CO2] (AT+AC), (ii) ambient temperature and elevated [CO2] (AT+EC), (iii) elevated temperature and ambient [CO2] (ET+AC), and (iv). elevated temperature and [CO2] (ET+EC). Each treatment was replicated four times. Diameter growth was monitored with a band dendrograph at 15-min intervals throughout the growing seasons of 1997, 1998 and 1999. Over the monitoring period, diameter growth began 2-3 weeks earlier in trees in the ET+EC and ET+AC chambers than in trees in the AT+AC and AT+EC chambers. However, the cessation of growth occurred about a week later in trees in the ET+EC, ET+AC and AT+EC chambers compared with the AT+AC chambers. The duration of the growing season was 115 and 108 days in the ET+EC and ET+AC chambers, respectively, and 95 and 84 days in the AT+EC and AT+AC chambers, respectively. The ET+AC and ET+EC treatments enhanced diameter growth most early in the growing season, whereas in trees in the AT+AC and AT+EC treatments diameter growth rate was highest in the middle of the growing season. Diameter growth rate leveled off more slowly in trees in the ET+EC and AT+EC treatments than in the other treatments. The growth response to elevated T, elevated [CO2] or both decreased with time and it was less than the maximum observed in other studies for small seedlings and under optimal growth conditions. Nevertheless, cumulative diameter growth for the 3-year period was 67% greater in trees in the ET+EC treatment, and 57 and 26% greater in trees in the AT+EC and ET+AC treatments, respectively, compared with trees in the AT+AC treatment. Over the 3 years, [CO2] had a statistically significant (P < 0.10) effect on both absolute and relative diameter growth, but the interaction between [CO2] and temperature was not significant. 相似文献
12.
Influence of nitrogen and phosphorous availability and ozone stress on Norway spruce seedlings 总被引：1，自引：0，他引：1
Four-year-old Norway spruce (Picea abies L. (Karst.)) seedlings were exposed to ambient and elevated (1.5 x ambient in 1997 and 1.6 x ambient in 1998) ozone concentrations [O3] and three nitrogen (N) and two phosphorus (P) availabilities: "optimal" values (control); 70% of the control N and P values (LN and LP); and 150% of the control N value (HN). Treatments were applied in an open-field ozone fumigation facility during the 1997 and 1998 growing seasons. Effects on growth, mineral and pigment concentrations, stomatal conductance and ultrastructure of needles were studied. The HN treatment increased growth significantly, whereas elevated [O3] had a slight or variable impact on growth and biomass allocation in all N treatments. Although there were no significant effects of the LP treatment on plant growth during the second year, there was a reduction in 1-year-old shoot dry mass in the elevated O3 + LP treatment at the end of the experiment. There were no significant treatment effects on mineral concentrations of current-year and 1-year-old needles at the final harvest. In response to the HN treatment, chlorophyll a and b and carotenoid concentrations increased significantly in current-year needles. Chlorophyll a/b ratio decreased in response to elevated [O3] alone, but increased in seedlings in the O(3) + LP treatment. Stomatal conductance of current-year needles decreased with increasing N availability, but increased in response to elevated [O3]. However, the O3-induced increase in stomatal conductance was less in the LN and LP treatments than in the control treatment. In chloroplasts of current-year needles, increased N availability decreased mean starch grain area, but increased the number of plastoglobuli. We conclude that Norway spruce seedlings are relatively tolerant to slightly elevated [O3], and that nitrogen and phosphorus imbalances do not greatly affect the influence of O3 on this species when the exposure lasts for two growing seasons or less. 相似文献
13.
The superoxide dismutase (SOD EC 1.15.1.1) activity in Scots pine (Pinus sylvestris) and Norway spruce (Picea abies L. Karst.) needles in urban and rural trees of northern Finnish populations was studied. Enzyme activity was higher in pine than in spruce needles. Two pine clones from eastern Finland and Lapland revealed great differences in specific SOD enzyme activity. 相似文献
14.
One‐year‐old container‐grown seedlings were planted in spring on clear cut areas: the Norway spruce (Picea abies) on a moist upland site (Myrtillus‐type) and Scots pine (Pinus sylvestris) on a dryish upland site (Vaccinium‐type). While still in the nursery, half of the seedlings of each species had been inoculated during the previous summer, with a uninucleate Rhizoctonia sp., a root dieback fungus. At outplanting all the seedlings appeared healthy and had a normal apical bud, although the height of the inoculated seedlings was less than that of the uninoculated control seedlings. At the end of the first growing season after planting, the mortality of inoculated Scots pine and Norway spruce seedlings was 25 and 69%, respectively. After two growing seasons the mortality of inoculated seedlings had increased to 38% for Scots pine and 93% for Norway spruce. The mortality of control seedlings after two growing seasons in the forest was 2% for Scots pine and 13% for Norway spruce. After outplanting the annual growth of inoculated seedlings was poor compared with the growth of control seedlings. These results show that, although Rhizoctonia‐affected seedlings are alive and green in the nursery, the disease subsequently affects both their survival and growth in the forest. 相似文献
15.
Conidia of Gremmeniella abietina infected and caused disease symptoms in annual shoots of both Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) seedlings. In Norway spruce shoots the infection remained largely latent, with only a few seedlings showing symptoms. Mycelial growth inside the shoots was faster in Scots pine than in Norway spruce and was favoured by low temperature in both hosts. The shoots of Norway spruce seedlings had higher endophyte populations than those of Scots pine, and the populations were decreased by low temperatures. Reductions in the normal epiphytic or endophytic flora by acid mist treatments seemed to favour the development of G. abietina. 相似文献
16.
Nitrogen availability modifies the ozone responses of Scots pine seedlings exposed in an open-field system 总被引：1，自引：0，他引：1
Three-year-old Scots pine (Pinus sylvestris L.) seedlings were exposed to either ambient or elevated (1.5-1.6 x ambient) ozone concentration ([O3]) for three growing seasons in an open-field fumigation facility where they were irrigated during the growing season with a nutrient solution providing nitrogen (N) at 70 (LN treatment), 100 (control) or 150% (HN treatment) of the optimum supply rate. Treatment effects were most evident during the third year of exposure, when the ambient [O3] + HN treatment enhanced whole-plant biomass, root/shoot dry weight ratio, needle pigment concentrations and the number of chloroplast plastoglobuli in the mesophyll cells in current-year (C) needles, whereas it reduced starch accumulation in C needles and abscission of 2-year-old (C+2) needles. In the control fertilization, 3 years of exposure to elevated [O3] decreased stem-base diameter and increased K concentration and electron density of chloroplast stroma in C needles. Plants in the HN treatment exposed for 3 years to elevated [O3] had significantly lower heights, current-year main shoot length and root/shoot dry mass ratio than control plants, and increased abscission of C+2 needles. In contrast, O3-induced changes in the ultrastructure of mesophyll cells were most evident in seedlings grown for 3 years in the LN treatment. We conclude that, in Scots pine, a relatively O3-tolerant species, chronic O3 exposure leads to cumulative growth reduction, increased needle abscission and changes in carbon allocation that are strongly influenced by plant N availability. 相似文献
17.
J Riikonen S Kontunen-Soppela V Ossipov A Tervahauta M Tuomainen E Oksanen E Vapaavuori J Heinonen M Kivimäenpää 《Tree physiology》2012,32(9):1102-1112
Northern forests are currently experiencing increasing mean temperatures, especially during autumn and spring. Consequently, alterations in carbon sequestration, leaf biochemical quality and freezing tolerance (FT) are likely to occur. The interactive effects of elevated temperature and ozone (O(3)), the most harmful phytotoxic air pollutant, on Norway spruce (Picea abies (L.) Karst.) seedlings were studied by analysing phenology, metabolite concentrations in the needles, FT and gas exchange. Sampling was performed in September and May. The seedlings were exposed to a year-round elevated temperature (+1.3 °C), and to 1.4× ambient O(3) concentration during the growing season in the field. Elevated temperature increased the concentrations of amino acids, organic acids of the citric acid cycle and some carbohydrates, and reduced the concentrations of phenolic compounds, some organic acids of the shikimic acid pathway, sucrose, cyclitols and steroids, depending on the timing of the sampling. Although growth onset occurred earlier at elevated temperature, the temperature of 50% lethality (LT(50)) was similar in the treatments. Photosynthesis and the ratio of photosynthesis to dark respiration were reduced by elevated temperature. Elevated concentrations of O(3) reduced the total concentration of soluble sugars, and tended to reduce LT(50) of the needles in September. These results show that alterations in needle chemical quality can be expected at elevated temperatures, but the seedlings' sensitivity to autumn and spring frosts is not altered. Elevated O(3) has the potential to disturb cold hardening of Norway spruce seedlings in autumn, and to alter the water balance of the seedling through changes in stomatal conductance (g(s)), while elevated temperature is likely to reduce g(s) and consequently reduce the O(3)-flux inside the leaves. 相似文献
18.
Fast, nondestructive measurement of frost hardiness in conifer seedlings by VIS+NIR spectroscopy 总被引：1，自引：0，他引：1
Frost hardiness development from mid-August to mid-November was evaluated in seedlings of three provenances of Norway spruce (Picea abies (L.) Karst.) and three provenances of Scots pine (Pinus sylvestris L.) raised at nurseries in north, central and south Sweden. Measurements of the visible + near infrared (VIS+NIR) spectra of shoots were made simultaneously with estimates of frost hardiness based on electrolyte leakage following artificial freezing. Nine physiological variables known to influence frost hardiness were measured throughout the experiment. Multivariate analysis showed that VIS+NIR spectra explained 69% and 72% of the variation in frost hardiness in Scots pine and Norway spruce, respectively. Stem lignification, dry weight fraction, and starch, glucose, fructose, galactose, sucrose, raffinose and stachyose concentrations together explained 80% and 85% of the variation in frost hardiness in Scots pine and Norway spruce, respectively when used as independent X variables in a partial least squares model. These physiological variables could be related to varying degrees with variation in the VIS+NIR spectra. We conclude that VIS+NIR spectroscopy provides a rapid nondestructive technique for measuring frost hardiness in conifer seedlings based on causal relationships between the spectra and the physiology of seedling frost hardiness. 相似文献
19.
Five-year-old Scots pine (Pinus sylvestris L.) seedlings were grown in open-top chambers at ambient and elevated (ambient + 400 &mgr;mol mol(-1)) CO(2) concentrations. Net photosynthesis (A), specific leaf area (SLA) and concentrations of nitrogen (N), carbon (C), soluble sugars, starch and chlorophyll were measured in current-year and 1-year-old needles during the second year of CO(2) enrichment. The elevated CO(2) treatment stimulated photosynthetic rates when measured at the growth CO(2) concentration, but decreased photosynthetic capacity compared with the ambient CO(2) treatment. Acclimation to elevated CO(2) involved decreases in carboxylation efficiency and RuBP regeneration capacity. Compared with the ambient CO(2) treatment, elevated CO(2) reduced light-saturated photosynthesis (when measured at 350 &mgr;mol mol(-1) in both treatments) by 18 and 23% (averaged over the growing season) in current-year and 1-year-old needles, respectively. We observed significant interactive effects of CO(2) treatment, needle age and time during the growing season on photosynthesis. Large seasonal variations in photosynthetic parameters were attributed to changes in needle chemistry, needle structure and feedbacks governed by whole-plant growth dynamics. Down-regulation of photosynthesis was probably a result of reduced N concentration on an area basis, although a downward shift in the relationship between photosynthetic parameters and N was also observed. 相似文献
20.
《Scandinavian Journal of Forest Research》2012,27(1-4):39-51
To trace any possible effects of air pollution stress and injuries on trees around a city centre, needles of Scots pine (Pinus Syivestris L.) and Norway spruce (Picea abies (L.) Karst.) from sites of different distances and directions from Stockholm were analysed. Comparisons were made between needles of different ages, a half to three and a half years old (C ‐ C + 3) for pine up to six and a half years old (C ‐ C + 6) for spruce. Epicuticular waxes, studied by scanning electron microscopy (SEM), showed age‐dependent but site‐independent changes. Different age‐patterns were found in the pine and spruce needles but no dust coverings or lesions were detected, irrespective of the sites. A proportionally increasing peroxidase activity (EC 1.11.1.7) with increasing needle‐age up to the third year was observed in both species. No certain indication of site‐effects, expressed by an unproportional increase of the enzyme activity with increasing needle‐age could be found. Chlorophyll a and b, phaeophytin a and b and carotenoid analyses on the corresponding materials only indicated disturbances in trees from some scattered sampling plots. Thus, neither could the pigment analyses reveal any signs of a general pollution stress in pine and spruce trees from the area in question. 相似文献