Ozone-induced free polyamine response in scots pine in northern Finland

The study aimed to assess the ozone-induced response in Scots pine (Pinus sylvestris L.) needles by measuring free polyamine concentrations. An open-top chamber experiment with realistically elevated ozone concentrations was carried out in northern Finland. A carry-over effect was detected: the concentrations of free polyamines, especially putrescine, were decreased at the beginning of the next growing season in the ozone-exposed trees. This indicates that the free polyamine pathway was not activated by ozone stress in Scots pines in northern conditions.     

Relations between Scots pine needle element concentrations and decreased needle longevity along pollution gradients

Scots pine (Pinus sylvestris L.) shoots were sampled along transects near one urban pollution source and two smelters. Needle Mg, P and K concentrations decreased from the second to the fourth age class linearly with needle survival along the urban pollution gradient. Still, over 80% of the average concentration of these nutrients remained in the fourth needle age class. Decreased needle longevity was closely related to the increased heavy metal concentrations near the smelters. Near the urban pollution source, it was related to the increased annual needle mass and the increased needle nutrient concentrations. Decreased Mn accumulation along with needle age was detected near all pollution sources. Leaching of Mn from needles and especially from soil as a cause of decreased needle concentrations is discussed.     

Total vs. internal element concentrations in Scots pine needles along a sulphur and metal pollution gradient

Analysis of foliar elements is a commonly used method for studying tree nutrition and for monitoring the impacts of air pollutants on forest ecosystems. Interpretations based on the results of foliar element analysis may, however, be different in nutrition vs. monitoring studies. We studied the impacts of severe sulphur and metal (mainly Cu and Ni) pollution on the element concentrations (Al, Ca, Cu, Fe, K, Mg, Mn, Ni, P, Pb, S and Zn) in Scots pine (Pinus sylvestris L.) foliage along an airborne sulphur and metal pollution gradient. Emphasis was put on determining the contribution of air-borne particles that have accumulated on needle surfaces to the total foliage concentrations. A comparison of two soil extraction methods was carried out in order to obtain a reliable estimate of plant-available element concentrations in the soil. Element concentrations in the soil showed only a weak relationship with internal foliar concentrations. There were no clear differences between the total and internal needle S concentrations along the gradient, whereas at the plot closest to the metal smelter complex the total Cu concentrations in the youngest needles were 1.3-fold and Ni concentrations over 1.6-fold higher than the internal needle concentrations. Chloroform-extracted surface wax was found to have Ni and Cu concentrations of as high as 3000 and 600 microg/g of wax, respectively. Our results suggest that bioindicator studies (e.g. monitoring studies) may require different foliar analysis techniques from those used in studies on the nutritional status of trees.     

Retrospective bioindication of stratospheric ozone and ultraviolet radiation using hydroxycinnamic acid derivatives of herbarium samples of an aquatic liverwort

We analyzed bulk UV absorbance of methanolic extracts and levels of five UV-absorbing compounds (hydroxycinnamic acid derivatives) in 135 herbarium samples of the liverwort Jungermannia exsertifolia subsp. cordifolia from northern Europe. Samples had been collected in 1850–2006 (96% in June–August). Both UV absorbance and compound levels were correlated positively with collection year. p-Coumaroylmalic acid (C1) was the only compound showing a significant (and negative) correlation with stratospheric ozone and UV irradiance in the period that real data of these variables existed. Stratospheric ozone reconstruction (1850–2006) based on C1 showed higher values in June than in July and August, which coincides with the normal monthly variation of ozone. Combining all the data, there was no long-term temporal trend from 1850 to 2006. Reconstructed UV showed higher values in June–July than in August, but again no temporal trend was detected in 1918–2006 using the joint data. This agrees with previous UV reconstructions.     

Inter- and intra-specific responses to elevated ozone and chamber climate in northern birches

We studied the responses of micropropagated, northern provenances of downy, mountain and silver birches to elevated ozone (O₃) and changing climate using open-top chambers (OTCs). Contrary to our hypothesis, northern birches were sensitive to O₃, i.e. O₃ levels of 31-36 ppb reduced the leaf and root biomasses by −10%, whereas wood biomass was affected to a lesser extent. The warmer and drier OTC climate enhanced growth in general, though there were differences among the species and clones, e.g. in bud burst and biomass production. Inter- and intra-specific responses to O₃ and changing climate relate to traits such as allocation patterns between the above- and belowground parts (i.e. root/shoot ratio), which further relate to nutrient and water economy. Our experiments may have mimicked future conditions quite well, but only long-term field studies can yield the information needed to forecast responses at both tree and ecosystem levels.     

Greenhouse gases in non-oxygenated and artificially oxygenated eutrophied lakes during winter stratification

Concentrations of dissolved methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) were measured in the water columns of non-oxygenated and artificially oxygenated, ice-covered eutrophied lakes in the mid-boreal zone in Finland during late winter 1997 and 1999. Sampling was conducted during winter stratification, the critical period for oxygen (O2) deficiency in seasonally ice-covered, thermally stratified lakes. Oxygen concentrations were maintained at least at a moderate level throughout the oxygenated water columns, whereas the non-oxygenated columns suffered anoxic hypolimnia. The mean concentrations of dissolved CH4 exceeding the atmospheric equilibrium were greater in the non-oxygenated water columns (20.6-154 microM) than in the oxygenated ones (0.01-1.41 microM). In contrast, the mean excess CO2 concentrations varied less between the non-oxygenated and oxygenated sites (0.28-0.47 and 0.25-0.31 mM, respectively). Oxygenated water columns had greater mean excess concentrations of N2O (0.018-0.032 microM) than the non-oxygenated ones (0.005-0.024 microM). If the accumulated greenhouse gas stores in the water columns during winter are assumed to be released to the atmosphere during the spring overturn, the global warming potentials (GWP, time horizon 100 yr) of these potential emissions at the non-oxygenated, eutrophic study sites ranged from 177 to 654 g CO2 equivalent (CO2-e) m-2 compared with 144 to 173 g CO2-e m-2 at the oxygenated sites. The increase in the accumulation of CH4 was the main reason for the higher GWP of the non-oxygenated sites. Anthropogenic eutrophication of lake ecosystems can generate increased CH4 emissions due to associated O2 depletion of their sediment and water column.     

Long-term evaluation of the needle surface wax condition of Pinus sylvestris around different industries in Lithuania

The aim of our study was to evaluate the annual dynamics of needle surface wax erosion and wettability in Scots pines exposed to a gradient of industrial pollutants emitted from the main factories of Lithuania: a nitrogen fertilizer factory, an oil refinery and a cement factory. Decreased emissions (in the case of the oil refinery and the cement factory) were reflected in the increased structural surface area (SSA, i.e. area covered by tubular waxes) on the needles. The nearly constant amount of emissions from the nitrogen fertilizer factory within the 1994-2000 period corresponded to negligible annual differences in SSA. Annual changes in the hydrophobicity of needles on the investigated transects were small. Despite the decreased pollution within the 7-year period, industrial emissions are still causing significantly accelerated wax erosion and increased wettability in needles sampled from the stands most heavily affected by pollutants.     

Changes in the concentrations of phenolics and photosynthates in Scots pine (Pinus sylvestris L.) seedlings exposed to nickel and copper

Studies were done on the effects of elevated soil concentrations of copper (Cu) and (Ni) on foliar carbohydrates and phenolics in Scots pine (Pinus sylvestris L.). Four year-old seedlings were planted in pots filled with metal-treated mineral forest soil in early June. The experimental design included all combinations of four levels of Cu (0, 25, 40 and 50 mg kg(-1) soil dw) and Ni (0, 5, 15 and 25 mg kg(-1) soil dw). Current year needles were sampled for soluble sugar, starch and phenolics at the end of September. Ni increased sucrose concentration in the needles, indicating disturbances in carbohydrate metabolism. Trees exposed to Ni had higher concentrations of condensed tannins compared with controls. In contrast, concentrations of several other phenolic compounds decreased when seedlings were exposed to high levels of Cu or to a combination of Ni and Cu. The results suggest that concentrations of phenolics in Scots pine needles vary in their responses to Ni and Cu in the forest soil.     

Acid deposition and the element composition of pine tree rings

The element contents of pine tree rings (Pinus sylvestris L.) were analyzed in five areas differing in the level of sulphur deposition. The elements studied and their average content in xylem were as follows:

aluminium 4.2, manganese 65, zinc 8.4, potassium 390, rubidium 2.2, calcium 930, magnesium 131, phosphorus 38, sulphur 56, nitrogen 0.65, boron 4.3 and molybdenum 0.03 mg/kg.

The contents of aluminium, potassium and rubidium were higher in tree rings from the 1950's on, particularly in southern Finland. The increase is probably due to acid deposition in the soil.     

Diversifying forest expertise: forest journals narrating policy change

ABSTRACT

During policy change, the role of the actors communicating the change to different audiences is accentuated. The media plays an increasing role, either as an actor or by providing a stage for other actors. In particular, specialised journals represent an influential, albeit understudied, sphere of policy studies. We use the narrative policy framework complemented with frame analysis to trace how specialised media can affect policy implementation through implicit suggestions for action. Using this combined approach, we analyse how specialised forest journals, which are the most important forest information source for Finnish forest owners, have conveyed the renewal of forest legislation in Finland. The core message of the journals is that forest owners should, despite their new freedom granted by the reform, rely on experts rather than experimenting when managing their forests. This suggests that the media contributes to a path-dependent continuation of a forest policy that is based on a rationalistic exploitation ethos. The innovative potential, which the policy change aimed at encouraging, is thereby partially undermined. However, the analysis of the narratives also reveals that forest expertise and professionalism are diversifying. This notion is important as diversity can eventually lead to narratives supporting more fundamental change in forests management.