Current-year Needles Research Articles

The effect of industrial air pollution on membrane lipid composition of Scots pine (Pinus sylvestris L.) needles

This work was undertaken to determine lipids changes in needles of Scots pine (<em>Pinus sylvestris </em>L.) populations growning on polluted stands near a phosphate fertilizer factory in Luboń, and copper smelter in Głogów and in a control area in Kórnik. Needles from polluted areas had a lower content of total phospholipids than samples from the unpolluted site. Greater changes were detected in membranes of needles collected in October and January. In comparison with the control total phospholipid in needles of populations from polluted areas were 14 to 33% lower. Phosphatidylcholine (PC) phosphatidylethanolamine (PE) and phosphatidylglicerol (PG) were the dominant phospholipids. The analysis of fatty acids in phospholipid fraction showed a decrease of linoleic acid (18:2) and linolenic acid (18:3) contents. The level of polyunsaturated fatty acids in needles of three populations from polluted areas was up to 40% lower as compared with the control. Moreover, phospholipids and their fatty acids showed seasonal fluctuations. The contents of PC, PG and PE increased in autumn and in winter, during the process of cold acclimation. In July, current-year needles did not show significant differences in membrane lipid composition between the polluted areas of Scots pine populations. The results suggest that the lipid changes of needles could be associated with disturbances in phohospholipid metabolism, caused by environmental pollution.

Nutrient loading of Norway spruce seedlings hastens bud burst and enhances root growth after outplanting

We studied the effects of late season nutrient loading (NLOAD) on the timing of bud burst, growth and changes in nitrogen (N) concentrations in the first growing season after seedlings were outplanted. Two-year-old Norway spruce (Picea abies (L.) Karst.) seedlings with three foliar nitrogen concentration levels (NLOAD levels 11.3, 22.5 and 27.5 g N kg for L, M- and H-seedlings, respectively) were examined in the following three experiments: root growth capacity test (RGC), rooting experiment in the field and soil fertility experiment (‘rich’ or ‘poor’ soil) in the field. Bud burst in RGC was monitored daily and foliar N concentration (field experiments), height and root growth (rooting experiment) at monthly intervals. With respect to the RGC test, no differences in root growth were observed among the three NLOAD levels, but buds of H-seedlings burst 2–6 days earlier than others. In the rooting experiment, nutrient loading increased height and root growth but did not affect the timing of height growth. In the soil fertility experiment, foliar N of H- and M-seedlings decreased rapidly, but the decline was slower in rich soil. Current-year needles had more N in seedlings growing in rich soil and the N concentration declined until height growth ceased whereafter it increased until autumn. Improved growth from nutrient loading seems to last only for the first season after planting and the greatest benefits are enjoyed by seedlings planted in poor soils.-1

Epicuticular wax on stomata of damaged silver fir trees (Abies alba Mili.)

Condition of epistomatal wax on the abaxial surface of the current and previous-year needles of damaged silver fir trees (<em>Abies alba</em> Mill.), both from the polluted Risnjak and "clean" Donja Dobra sites in Gorski Kotar region, both influenced by pollutants coming from Europe, during two years, three times a year, were examined with Scanning Electron Microscope. In the course of time the wax tubules on the epistomatal rims of stomata in polluted, but also in "clean" needles surface, become fused and agglomerated rapidly to various extents of morphologically different types of amorphous wax crusts, primarily compact and particulate ones. This process begins very early, especially in polluted Risnjak site, and may be interpreted as a possible result of air pollution. However, the recrystalization, or production of new tubules, also appears relatively quickly in mostly cases. Quantitative estimations indicate a very large total amount of amorphous wax crusts in the current-year needles, and a very high percentage of the same wax in previous-year needles. Amorphous wax crusts cover stomatal pores, as well as the rims, disturbing the normal gas exchange. Statistically there is a signicant tendency of increase in wax degradation in the needles of the polluted site in comparison with those of the unpolluted one, but there is an insignificant wax degradation among the needles of damaged trees within each site. These results confirmed most of the research done in our preliminary report.

Species-specific and needle age-related responses of photosynthesis in two Pinus species to long-term exposure to elevated CO2 concentration

There is, so far, no common conclusion about photosynthetic responses of trees to long-term exposure to elevated CO2. Photosynthesis and specific leaf area (SLA) of 1-year-old and current-year needles in Pinus koraiensis and P. sylvestriformis grown in open-top chambers were measured monthly for consecutive two growing seasons (2006, 2007) after 8–9 years of CO2 enrichment in northeastern China, to better understand species-specific and needle age-related responses to elevated CO2 (500 μmol mol−1 CO2). The light-saturated photosynthetic rates (P Nsat) increased in both species at elevated CO2, but the stimulation magnitude varied with species and needle age. Photosynthetic acclimation to elevated CO2, in terms of reduced V cmax (maximum carboxylation rate) and J max (maximum electron transport rate), was found in P. koraiensis but not in P. sylvestriformis. The photosynthetic parameters (V cmax, J max, P Nsat) measured in different-aged needles within each species responded to elevated CO2 similarly, but elevated CO2 resulted in much pronounced variations of those parameters in current-year needles than in 1-year-old needles within each species. This result indicated that needle age affects the magnitude but not the patterns of photosynthetic responses to long-term CO2 enrichment. The present study indicated that different species associated with different physioecological properties responded to elevated CO2 differently. As global change and CO2 enrichment is more or less a gradual rather than an abrupt process, long-term global change experiments with different plant species are still needed to character and better predict the global change effects on terrestrial ecosystems.

Tree species effects on ecosystem water-use efficiency in a high-elevation, subalpine forest

Ecosystem water-use efficiency (eWUE; the ratio of net ecosystem productivity to evapotranspiration rate) is a complex landscape-scale parameter controlled by both physical and biological processes occurring in soil and plants. Leaf WUE (lWUE; the ratio of leaf CO(2) assimilation rate to transpiration rate) is controlled at short time scales principally by leaf stomatal dynamics and this control varies among plant species. Little is known about how leaf-scale variation in lWUE influences landscape-scale variation in eWUE. We analyzed approximately seven thousand 30-min averaged eddy covariance observations distributed across 9 years in order to assess eWUE in two neighboring forest communities. Mean eWUE was 19% lower for the community in which Engelmann spruce and subalpine fir were dominant, compared to the community in which lodgepole pine was dominant. Of that 19% difference, 8% was attributed to residual bias in the analysis that favored periods with slightly drier winds for the spruce-fir community. In an effort to explain the remaining 11% difference, we assessed patterns in lWUE using C isotope ratios. When we focused on bulk tissue from older needles we detected significant differences in lWUE among tree species and between upper and lower canopy needles. However, when these differences were scaled to reflect vertical and horizontal leaf area distributions within the two communities, they provided no power to explain differences in eWUE that we observed in the eddy covariance data. When we focused only on bulk needle tissue of current-year needles for 3 of the 9 years, we also observed differences in lWUE among species and in needles from upper and lower parts of the canopy. When these differences in lWUE were scaled to reflect leaf area distributions within the two communities, we were able to explain 6.3% of the differences in eWUE in 1 year (2006), but there was no power to explain differences in the other 2 years (2003 and 2007). When we examined sugars extracted from needles at 3 different times during the growing season of 2007, we could explain 3.8-6.0% of the differences in eWUE between the two communities, but the difference in eWUE obtained from the eddy covariance record, and averaged over the growing season for this single year, was 32%. Thus, overall, after accounting for species effects on lWUE, we could explain little of the difference in eWUE between the two forest communities observed in the eddy covariance record. It is likely that water and C fluxes from soil, understory plants, and non-needle tissues, account for most of the differences observed in the eddy covariance data. For those cases where we could explain some of the difference in eWUE on the basis of species effects, we partitioned the scaled patterns in lWUE into two components: a component that is independent of canopy leaf area distribution, and therefore only dependent on species-specific differences in needle physiology; and a component that is independent of species differences in needle physiology, and only dependent on species-specific influences on canopy leaf area distribution. Only the component that is dependent on species influences on canopy leaf area distribution, and independent of inherent species differences in needle physiology, had potential to explain differences in eWUE between the two communities. Thus, when tree species effects are important, canopy structure, rather than species-specific needle physiology, has more potential to explain patterns in eWUE.

An Ornamental Swiss Stone Pine (Pinus cembra) in Wisconsin is a Host of the Shoot Blight Pathogen Diplodia pinea.

Swiss stone pine (Pinus cembra) is a slow-growing, hardy tree native to high-mountain regions of Europe from the Alps to the Carpathians. It also is planted as an ornamental in North America. Shoot blight and branch dieback were observed in the fall of 2008 on a single, 25- to 30-year-old Swiss stone pine growing on the University of Wisconsin-Madison campus. This tree is located between two mature Austrian pines (P. nigra) that exhibit symptoms of Diplodia blight and show signs of the conifer pathogen Diplodia pinea. Approximately 20% of the Swiss stone pine shoots were affected with needles and stems killed before full elongation. Symptom development appeared to have progressed from tips into older portions of branches with several years' growth often heavily resinous and necrotic. Five samples each of needles, stems, and cones bearing erumpent, black pycnidia were collected for microscopic examination. Each sample yielded conidia consistent with those of D. pinea (2). Using tannic acid agar (TAA) (1) on which autoclaved pine needles were placed to induce sporulation, this fungus was cultured from all 15 samples. The identity of the pathogen was confirmed as D. pinea with species-specific PCR primers (4) that allow differentiation from the similar fungus D. scrobiculata. Single-conidial isolate 09-03 from the affected Swiss stone pine was used to inoculate potted seedlings of this species in a greenhouse. Growing shoots of 12 seedlings were wounded by removing a needle fascicle and then were inoculated by placing on the wound a 5-mm-diameter plug cut from an actively growing colony on water agar (WA). Noncolonized WA plugs were placed on five wounded control seedlings, and five nonwounded control seedlings were used. Seedlings were covered with plastic bags to maintain high humidity for 2 weeks and then the bags were removed. The initial symptom, present 1 week after inoculation, was chlorosis of the bases of current-year needles near the point of inoculation. Affected needles became necrotic and pycnidia were visible on some by 10 days after inoculation. Needle chlorosis, necrosis, and dark discoloration of vascular tissue had developed on 11 of 12 inoculated seedlings by 6 weeks after inoculation, but not on wounded or nonwounded control seedlings. At that time, one or more symptomatic needles and a stem segment from each inoculated seedling and comparable material from control seedlings were surface disinfested and placed on TAA. The pathogen was cultured from needles of 10 of 12 inoculated seedlings and from stems of all inoculated seedlings. The fungus was not cultured from needles of control seedlings, but was cultured from stems of 2 of 10 control seedlings, one wounded and one nonwounded. D. pinea often severely damages species in the Pinus subgenus Diploxylon (two- and three-needle pines), but it is much less frequently reported as a cause of damage to hosts in the subgenus Haploxylon (five-needle pines), which includes Swiss stone pine. Although an unidentified Diplodia species was listed among fungi cultured from a healthy shoot of P. cembra (3), to our knowledge this is the first report of D. pinea as a pathogen of Swiss stone pine.

Decoupling the influence of leaf and root hydraulic conductances on stomatal conductance and its sensitivity to vapour pressure deficit as soil dries in a drained loblolly pine plantation

The study examined the relationships between whole tree hydraulic conductance (K(tree)) and the conductance in roots (K(root)) and leaves (K(leaf)) in loblolly pine trees. In addition, the role of seasonal variations in K(root) and K(leaf) in mediating stomatal control of transpiration and its response to vapour pressure deficit (D) as soil-dried was studied. Compared to trunk and branches, roots and leaves had the highest loss of conductivity and contributed to more than 75% of the total tree hydraulic resistance. Drought altered the partitioning of the resistance between roots and leaves. As soil moisture dropped below 50%, relative extractable water (REW), K(root) declined faster than K(leaf). Although K(tree) depended on soil moisture, its dynamics was tempered by the elongation of current-year needles that significantly increased K(leaf) when REW was below 50%. After accounting for the effect of D on g(s), the seasonal decline in K(tree) caused a 35% decrease in g(s) and in its sensitivity to D, responses that were mainly driven by K(leaf) under high REW and by K(root) under low REW. We conclude that not only water stress but also leaf phenology affects the coordination between K(tree) and g(s) and the acclimation of trees to changing environmental conditions.

Effect of simulated acid fog on membrane-bound calcium (mCa) in fir (Abies firma) and cedar (Cryptomeria japonica) mesophyll cells

The decline of virgin fir (Abies firma) forest at Mt. Oyama has been reported. Related field observations suggest that high acidity fog is linked with its decline. However, cedar (Cryptomeria japonica) in the same area shows no symptoms of decline. For assessing effects of acid fog on membrane-bound calcium (mCa) of the leaf mesophyll cells, 9-year-old seedlings of fir (Abies firma) and 8-year-old seedlings of cedar (Cryptomeria japonica) were exposed twice a week to simulated acid fog (SAF at pH 3 with pH 5 as control) for 2 h per day in a chamber during May–December 2007 (except August). Current and 1-year-old needles were collected from seedlings and analyzed at 1-month intervals. For current-year needles of fir, mCa levels in cells exposed to SAF at pH 3 were significantly lower than in cells exposed to pH 5, especially during September 2007–March 2008. In contrast, it is noteworthy that mCa levels of cedar were maintained as virtually constant irrespective of SAF acidity, indicating that fir is more sensitive to acid fog than is cedar. Based on these results, mCa loss by acid fog might also be caused in the declining virgin fir forest at Mt. Oyama.

Changes in needle nitrogen partitioning and photosynthesis during 80 years of tree ontogeny in Picea abies

Needle nitrogen partitioning and photosynthesis of Norway spruce were studied in a forest chronosequence in Jarvselja Experimental Forest, Estonia. Current- and previous-year shoots were sampled from upper and lower canopy positions in four stands, ranging in age from 13 to 82 years. A/c i curves were determined to obtain maximum carboxylation rate (V cmax) and maximum rate of electron transport (J max), whereas needle nitrogen partitioning into carboxylation (P R), bioenergetics associated with electron transport (P B) and thylakoid light harvesting components (P L) was calculated from the values of V cmax, J max and leaf chlorophyll concentration. The greatest changes in studied needle characteristics took place between tree ages of 13 and 26 years, and this pattern was independent of needle age and canopy position. Needle mass per projected area (LMA) was lowest in the 13-year-old stand and mass-based nitrogen concentration (NM) was generally highest in that stand. The values of LMA were significantly higher and those of NM lower in the 26-year-old stand. Mass-based V cmax and J max were highest in the 13-year-old stand. Area-based photosynthetic capacity was independent of tree age. The proportion of photosynthetic nitrogen (P R, P B and P L) was highest and that of non-photosynthetic nitrogen lowest in the 13-year-old stand. Current-year needles had lower LMA and P L, but higher photosynthetic capacity compared to 1-year-old foliage. Needles from lower canopy positions exhibited lower LMA, area-based nitrogen concentration and photosynthetic capacity than needles from upper canopy. The period of substantial reductions in needle photosynthetic capacity and changes in nitrogen partitioning coincides with the onset of reproductive phase during tree ontogeny.

Seasonal response of photosynthetic electron transport and energy dissipation in the eighth year of exposure to elevated atmospheric CO2 (FACE) in Pinus taeda (loblolly pine)

To determine the effect of growth under elevated CO(2) partial pressures (pCO(2)) on photosynthetic electron transport and photoprotective energy dissipation, we examined light-saturated net photosynthetic CO(2) assimilation (A(sat)), the capacity for photosynthetic O(2) evolution, chlorophyll fluorescence emission and the pigment composition of upper-canopy loblolly pine needles in the eighth year of exposure to elevated pCO(2) (20 Pa above ambient) at the free-air CO(2) enrichment facility in the Duke Forest. During the summer growing season, A(sat) was 50% higher in current-year needles and 24% higher in year-old needles in elevated pCO(2) in comparison with needles of the same age cohort in ambient pCO(2). Thus, photosynthetic down-regulation at elevated pCO(2) was observed in the summer in year-old needles. In the winter, A(sat) was not significantly affected by growth pCO(2). Reductions in A(sat), the capacity for photosynthetic O(2) evolution and photosystem II (PSII) efficiency in the light-acclimated and fully-oxidized states were observed in the winter when compared to summer. Growth at elevated pCO(2) had no significant effect on the capacity for photosynthetic O(2) evolution, PSII efficiencies in the light-acclimated and fully-oxidized states, chlorophyll content or the size and conversion state of the xanthophyll cycle, regardless of season or needle age cohort. Therefore, we observed no evidence that photosynthetic electron transport or photoprotective energy dissipation responded to compensate for the effects of elevated pCO(2) on Calvin cycle activity.

Artificial recharge of groundwater through sprinkling infiltration: Impacts on forest soil and the nutrient status and growth of Scots pine

We studied the chemical changes in forest soil and the effects on Scots pine trees caused by continuous sprinkling infiltration over a period of two years, followed by a recovery period of two years. Infiltration increased the water input onto the forest soil by a factor of approximately 1000. After one year of infiltration, the pH of the organic layer had risen from about 4.0 to 6.7. The NH 4-N concentration in the organic layer increased, most probably due to the NH 4 ions in the infiltration water, as the net N mineralization rate did not increase. Sprinkling infiltration initiated nitrification in the mineral soil. Macronutrient concentrations generally increased in the organic layer and mineral soil. An exception, however, was the concentration of extractable phosphorus, which decreased strongly during the infiltration period and did not show a recovery within two years. The NO 3-N and K concentrations had reverted back to their initial level during the two-year recovery period, while the concentrations of Ca, Mg and NH 4-N were still elevated. Nutrient concentrations in the pine needles increased on the infiltrated plots. However, the needle P concentration increased, despite the decrease in plant-available P in the soil. Despite the increase in the nutrient status, there were some visible signs of chlorosis in the current-year needles after two years of infiltration. The radial growth of the pines more than doubled on the infiltrated plots, which suggests that the very large increase in the water input onto the forest floor had no adverse effect on the functioning of the trees. However, a monitoring period of four years is not sufficient for detecting potential long term detrimental effects on forest trees.

Effect of 3 years' free-air exposure to elevated ozone on mature Norway spruce ( Picea abies (L.) Karst.) needle epicuticular wax physicochemical characteristics

We examined the effect of ozone (O 3) on Norway spruce ( Picea abies) needle epicuticular wax over three seasons at the Kranzberg Ozone Fumigation Experiment. Exposure to 2× ambient O 3 ranged from 64.5 to 74.2 μl O 3 l −1 h AOT40, and 117.1 to 123.2 nl O 3 l −1 4th highest daily maximum 8-h average O 3 concentration. The proportion of current-year needle surface covered by wax tubes, tube aggregates, and plates decreased ( P = 0.011) under 2× O 3. Epistomatal chambers had increased deposits of amorphous wax. Proportion of secondary alcohols varied due to year ( P = 0.004) and O 3 treatment ( P = 0.029). Secondary alcohols were reduced by 9.1% under 2× O 3. Exposure to 2× O 3 increased ( P = 0.037) proportions of fatty acids by 29%. Opposing trends in secondary alcohols and fatty acids indicate a direct action of O 3 on wax biosynthesis. These results demonstrate O 3-induced changes in biologically important needle surface characteristics of 50-year-old field-grown trees.

Long term effect of liming and fertilization on ectomycorrhizal colonization and tree growth in old Scots pine (Pinus sylvestris L.) stands

In this study, we surveyed the long term effects of liming and fertilizing in old Scots pine stands on the ectomycorrhiza (ECM) colonization, tree growth and needle nutrient concentration 35 years later. Four mature stands of Scots pine on low productive mineral soil were limed in 1959 and 1964 with total doses of limestone ranging from 3 to 15 Mg ha−1 and fertilized with nitrogen (N) in 1970. Thirty-five years after the first liming treatment, all stands were analysed for tree growth and needle nutrient concentrations and two of the stands were also analysed for ECM colonization. ECM colonization increased significantly with liming from 61.5% in the control plots to 88% in the plot with the highest limestone dose. ECM colonization increased with increasing pH in the humus layer from 62% colonization at pH = 3.5 to 90% at pH = 6.5 and decreased with increasing amount of extractable phosphorus (P) in the humus. Liming did not affect the frequencies of different ECM morphotypes or dead short root tips, the fine root biomass or necromass. ECM colonization was uncorrelated with needle nutrient concentrations or tree increment. Liming did not significantly affect tree growth. However, nutrient concentrations of current-year needles were affected by prior liming. Ca concentrations in current-year needles increased from approximately 15 mg g−1 in control treatments to more than 30 mg g−1 in limed plots, whereas concentrations of Mn, Al, Fe, and in two stands, B, decreased due to liming. In conclusion, liming with doses up to 15 Mg ha−1 was detectable in stands 35 years after treatment. The liming significantly increased the ECM colonization of Scots pine fine roots, increased the needle nutrient concentration of Ca and decreased the needle concentrations of Mn, Al, and Fe.

Elevated CO2 concentration affects leaf photosynthesis-nitrogen relationships in Pinus taeda over nine years in FACE

To investigate whether long-term elevated carbon dioxide concentration ([CO(2)]) causes declines in photosynthetic enhancement and leaf nitrogen (N) owing to limited soil fertility, we measured photosynthesis, carboxylation capacity and area-based leaf nitrogen concentration (N(a)) in Pinus taeda L. growing in a long-term free-air CO(2) enrichment (FACE) facility at an N-limited site. We also determined how maximum rates of carboxylation (V(cmax)) and electron transport (J(max)) varied with N(a) under elevated [CO(2)]. In trees exposed to elevated [CO(2)] for 5 to 9 years, the slope of the relationship between leaf photosynthetic capacity (A(net-Ca)) and N(a) was significantly reduced by 37% in 1-year-old needles, whereas it was unaffected in current-year needles. The slope of the relationships of both V(cmax) and J(max) with N(a) decreased in 1-year-old needles after up to 9 years of growth in elevated [CO(2)], which was accompanied by a 15% reduction in N allocation to the carboxylating enzyme. Nitrogen fertilization (110 kg N ha(-1)) in the ninth year of exposure to elevated [CO(2)] restored the slopes of the relationships of V(cmax) and J(max) with N(a) to those of control trees (i.e., in ambient [CO(2)]). The J(max):V(cmax) ratio was unaffected by either [CO(2)] or N fertilization. Changes in the apparent allocation of N to photosynthetic components may be an important adjustment in pines exposed to elevated [CO(2)] on low-fertility sites. We conclude that fundamental relationships between photosynthesis or its component processes with N(a) may be altered in aging pine needles after more than 5 years of exposure to elevated atmospheric [CO(2)].

The essential oil qualitative and quantitative composition in the needles of Pinus sylvestris L. growing along industrial transects

The aim of this study was to evaluate composition of the essential oils in the needles of Pinus sylvestris growing in the areas affected by a cement factory (CF), and an oil refinery (OR). Volatile components of the needles were analyzed by GC and GC/MS. The most heavily polluted CF stand had significantly higher concentration of gamma-Terpinene, Caryophyllene oxide in the current-year needles, while higher concentration of delta-3-Carene, alpha-Terpinene, gamma-Terpinene and Terpinolene was documented for 1-year-old needles. The most heavily polluted OR stand had a significantly higher concentration of Sabinene+beta-Pinene, 1-epi-Cubenol in the current-year needles and a significantly higher concentration of Camphene, Sabinene+beta-Pinene, Myrcene, alpha-Cadinene, 1-epi-Cubenol in the 1-year-old needles than the least polluted site. Along transects an increase in the amount of some diterpenes and a decrease in the components of the shorter chain essential oils was observed. These effects could be at least partially attributed to SO(2).

Phytotoxicities of fluoranthene and phenanthrene deposited on needle surfaces of the evergreen conifer, Japanese red pine ( Pinus densiflora Sieb. et Zucc.)

Polycyclic aromatic hydrocarbons (PAHs) have been widely studied with respect to their carcinogenic and mutagenic effects on animals and human cells. Phenanthrene (PHE) and fluoranthene (FLU) effects on the needle photosynthetic traits of 2-year-old Japanese red pine ( Pinus densiflora Sieb. et. Zucc.) seedlings were investigated. Three months after fumigation of foliage with solutions containing these PAHs (10 μM each), FLU had negative effects on net photosynthesis at near-saturating irradiance, stomatal conductance, initial chlorophyll fluorescence, and the contents of total chlorophyll, magnesium, and ribulose 1,5-bisphosphate carboxylase (rubisco) of current-year needles. PHE had similar negative effects to FLU but in lesser magnitude. The effects of the PAHs were mitigated by the addition of an OH-radical scavenger (mannitol) into the PAH solutions. PAHs deposited on the surface of pine needles may induce the generation of reactive oxygen species in the photosynthetic apparatus, a manner closely resembling the action of the herbicide paraquat.

Variation in Scots pine needle longevity and nutrient conservation in different habitats and latitudes

Within-species variation in needle traits is an important characteristic of conifers enabling trees to grow in different environments. We compared mean needle age (NA), shoot growth, and nutrient conservation in Scots pine ( Pinus sylvestris L.) populations in different habitats and latitudes (peatlands and Vaccinium -type stands in Estonia (59°N) and Lapland (66°30′N)). In Vaccinium-type stands, trees with higher NA (mostly in Lapland) had lower shoot length increment and lower concentration of nitrogen and phosphorus in current-year needles than trees with low NA (mostly in Estonia). However, in peatlands, variation in NA (which was as high as in the Vaccinium-type stands) was weakly or insignificantly related to shoot growth and needle nutrient concentration. Within latitudes, pines with different shoot length increments and needle nutrient concentrations tend to have similar NAs. Resorption efficiency and concentration of nitrogen and phosphorus in senescent needles decreased with the initial concentrations of these nutrients in green needles. Our results demonstrate that slow growth and low needle nutrient concentration are not necessarily followed by higher NA and greater nutrient conservation in Scots pine. This is the opposite of the results often obtained in among-species comparisons or within species along latitudinal and altitudinal gradients.

Norway spruce needles as bioindicator of air pollution in the area of influence of the Šoštanj Thermal Power Plant, Slovenia

This paper reports the results of total sulphur content, photosynthetic pigments, ascorbic acid (vitamin C) and α-tocopherol (vitamin E) analysed in current-year needles of Norway spruce ( Picea abies (L.) Karst.) in the area influenced by sulphur emissions from the Šoštanj Thermal Power Plant (ŠTPP), Slovenia, in the period 1991–2004. Ten differently polluted sampling sites in the emission area of ŠTPP were selected. After desulphurization of emission gases from ŠTPP total sulphur content in needles decreased and vitality parameters of needles increased. Moreover, a strong correlation between the average annual emissions of SO 2 from ŠTPP and average annual sulphur content (increase) or average annual chlorophyll content (decrease) in current-year needles was found. The results showed that spruce needles may be an useful bioindicator for detecting changes in the emission rates of SO 2.

Implications of delayed soil thawing on trees: A case study of a Picea abies stand

The effects of experimentally delayed soil thawing were studied on a 32-year-old stand of Norway spruce [Picea abies (L.) Karst.] located in the eastern part of Finland. While the soil temperature at depths of 10 and 50 cm rose above 0°C at the beginning of May in the control treatment (CTRL), it stayed close to 0°C until mid-July in the delayed soil-thawing treatment (FROST). Budburst was delayed by a few days by the FROST treatment. Treatment affected the physiology of previous- and current-year needles, i.e. their electrical impedance, potential efficiency of photosystem II (F v/F m), and chlorophyll a and b content. At the end of the growing season, in November, both the area of the central cylinder and all of the measured dimensions inside the cylinder in the current needles and number of sieve cells in the previous year's needles were smaller in the FROST than the CTRL trees. At the same time, the fully developed dormant buds showed differences only in their side shoots, the width of the buds being smaller in the FROST than the CTRL trees. No effect was found on the onset of wood formation. In contrast, the radial increment tended to be faster in the delayed soil-thawing treatment during late summer.

Effects of nitrogen supply on photosynthetic and anatomical changes in current-year needles of Pinus koraiensis seedlings grown under two irradiances

We investigated the responses of photon-saturated photosynthesis rate (P sat) and its simultaneous acclimation of anatomy and nitrogen use patterns of current needles of Korean pine (Pinus koraiensis) seedlings grown under factorial combinations of two nitrogen levels and irradiances. Although N supply resulted in a significant increase of N content in needles under both irradiances, the increase of P sat tended to be suppressed only in shade (S). The significant increase of P sat in full sunlight (O) was associated with the increase of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) and chlorophyll (Chl) contents. In contrast, small increase of Chl content and no increase of RuBPCO content were found in S (90 % cut of full irradiance), which would result in a small increase of P sat. This result suggests that extra N is stocked in needles under shade for the growth in next season. With N supply, a significant decrease of specific leaf area (SLA) was detected only in O. This decrease of SLA was due to the increase of density of needle. Furthermore, the increase of needle density was not due to the increased number and size of mesophyll cells, but the increased density of each mesophyll cell. Therefore, although SLA changed in O, the change did not involve anatomical adaptation to use increased N effectively, at least observable by light microscopy. Hence, even though the SLA would change, N deposition will improve the photosynthetic capacity of Korean pine seedlings, not through the development of needle anatomy but through improvement of the allocation of N in both irradiances.