Development of fruiting bodies of large tree type of Gremmeniella abietina var. abietina and timing of infection on Scots pine inn northern Finland

The formation and maturing of the large tree type Gremmeniella abietina var. abietina fruiting bodies and their sporulation were investigated for 3 years on Scots pine (Pinus sylvestris) in northern Finland. This was done by monthly assessment of shoots in the field and in the laboratory. Infection caused by G. abietina var. abietina was dated on Scots pine by monthly covering with pollination bags and exposing branches during the growing season. Pycnidia appeared between August and September, 1 year after infection, and they started to release conidia between late June and early July, 2 years after infection. Fresh pycnidia and microconidia were formed during the following August and September in the infected shoots. The causal large tree type of G. abietina var. abietina did not produce apothecia on branches within 3 years of infection. Monthly covering and exposing branches showed that infection took place mainly between June and July.     

Temporal Changes in the State of a Pine Stand in a Bog Affected by Air Pollution in Northeast Estonia

We used the needle trace method to investigate changes in the state of a Scots pine (Pinus sylvestris L.) stand in a bog (Voorepera) in the north-eastern part of Estonia, the most polluted area of the country. Additionally, we chose six sampling sites in other parts of Northeast Estonia (polluted area) and eight sites in southern Estonia (unpolluted area) to compare the state of pine stands in different bogs. During the period of 1964–1997, the radial growth had increased from 0.27 to 2.16 mm yr^–1 and the annual shoot length from 0.10 to 0.28 m in Voorepera. Mean values of the period (1.13 mm yr^–1 and 0.26 m, respectively) were two and four times higher in Voorepera than the average of the other bogs (0.5 mm yr^–1 and 0.06 m, respectively). Maximum needle age fluctuated between three and five growing seasons in Voorepera, the mean (four growing seasons) was similar to that of other bogs (four growing seasons). Except radial growth, which was 0.6 mm yr^–1 in the polluted area and 0.4 mm yr^–1 in the unpolluted area, other indices of trees' health (shoot growth, needle age, nitrogen concentration in needles) and substrate conditions (water pH and N concentration) did not show clear differences between polluted and unpolluted areas. We conclude that air pollution from oil shale industry (thermal power plant and chemical factories) enhances the growth of pines in bogs, which can induce drastic changes in these ecosystems. However, the effect is currently obvious only in the vicinity of pollution sources.     

Estimating the onset of cambial activity in Scots pine in northern Finland by means of the heat-sum approach

We estimated the date of onset (Date(est)) of cambial activity by the pinning method in Scots pine (Pinus sylvestris L.) trees at Vanttauskoski (Site 1) and Laanila (Site 2) near the latitudinal limit of Scots pine in northern Finland. In each year and at each site, observations were made on a different set of five trees. The estimated dates of onset of cambial activity were compared with the corresponding heat sums, calculated in degree-days according to two models. Within years, Date(est) varied among trees by up to 15 days at Site 1 and up to 13 days at Site 2. Among years, mean Date(est) varied by 15.3 days at Site 1 and 12.0 days at Site 2. The overall mean Date(est) differed between sites by 6 days (June 5 at Site 1 and June 11 at Site 2). Among all trees in all years, the mean number of degree days (d.d.) calculated from mean daily temperature above a threshold of 5 degrees C before Date(est) ranged from 68.7 to 135 d.d. at Site 1 and from 37.4 to 154.7 d.d. at Site 2. Among years, the mean heat sum before Date(est )ranged from 94 to 112.5 d.d. at Site 1 and from 61.4 to 136 d.d. at Site 2. Variation among years in heat sum before Date(est) at Site 2 was highly significant, indicating that one or more factors other than, or in addition to, heat sum determines the onset of cambial activity in Scots pine. Similar results were obtained when heat sum was computed from the area between the sine wave generated by daily maximum and minimum temperature and the threshold temperature.     

Testing dependence between growth and needle litterfall in Scots pine--a case study in northern Finland

Both drought and fungal disease increase needle litterfall of Scots pine (Pinus sylvestris L.) trees, but most factors causing annual variation in needle litterfall are poorly understood. We hypothesized that radial growth and weather conditions favorable to growth correlate positively with needle litterfall with a lag equal to the number of needle cohorts (here being 5-6). We studied the time series of needle litterfall, stem increment, pollen cone litter and daily weather conditions in a Scots pine stand over 43 years (1961-2004). The cross-correlations of standardized time series were estimated with various lags. Model predictions of annual needle litterfall were tested against independent data. Changes in annual growth and needle litterfall correlated with lags of 0 and 4 years. The best predictors for needle litterfall were May to mid July temperature sum with a lag of 4 years, May rainfall with a lag of 2 years and September temperature with a lag of 6 years. Pollen cone litter correlated negatively with needle litterfall with a lag of 2 years. The study provided empirical evidence that needle litterfall of Scots pine in northern Finland is influenced by needle production and needle mass development that occurred 4 to 6 years earlier.     

Intra-annual height increment of Pinus sylvestris at high latitudes in Finland

Intra-annual height growth of Scots pine (Pinus sylvestris L.) in four stands was followed for up to four growing seasons (2000-2003) in the northern boreal zone in Lapland. Elongation of the leader shoot correlated with temperature sum expressed as degree-days. Total length of the leader shoot correlated with growth rate but not with duration of the height-growth period. The longer the annual shoot at the end of the season, the greater the height increment per degree- and growing day. Height-growth cessation was defined as the date when 95% of the total shoot length was achieved. In all stands and all years, height growth ceased when, on average, 41% of the relative temperature sum of the site was achieved (range of variation 38-43%). The relative temperature sum was calculated by dividing the actual temperature sum by the long-term mean for the site. Our results suggest that annual height growth is finished when a location-specific temperature sum threshold is attained.     

Excess nitrogen fertilization and the structure of Scots-pine needles

The effects of excess nitrogen fertilization on the structure of Scots-pine needles (Pinus sylvestris) were examined in Finnish Lapland. The trees were fertilized with calcium ammonium-nitrate, and the levels of nitrogen applied were 0, 75, 150, 250, 500 and 1000 kg N/ha, respectively. The thickness and width of the needle and thicknesses of the tissues were measured, and the conditions of various celltypes were classified at the light-microscopy level. In addition, the areas of the cell organelles were measured and the conditions of the chlomplasts and other cell compartments observed at the ultrastructural level. Larger needles and a thicker adaxial mesophyll were observed following excess N application (250–1000 kg N/ha). The natural xeromorphic structure of the conifer needles became more mesomorphic, possibly influencing the protection afforded against environmental stresses. A high level of nitrogen fertilization caused changes in the central cylinder, especially in the vascular bundle and the sclerenchyma. The needle nitrogen concentration was high in the highly fertilized trees and the boron concentration was simultaneously extremely low. As a consequence of the changes in the central cylinder, photoassimilate transport from the mesophyll to the phloem may be disturbed at high fertilization levels. The changes at the ultrastructural level, i.e. injuries to the chloroplast thylakoids and the plasma membrane, and the formation of lipid accumulations, were indicators of the adverse effects of excess nitrogen. With an increasing atmospheric-nitrogen load, lower nitrogen fertilization levels in pine forests naturally adapted to low soil N should be considered in forest management.     

Variation in needle longevity is related to needle-fascicle production rate in Pinus sylvestris

Latitudinal variation in needle longevity of conifers in response to climatic variability is a well-known phenomenon, but its significance has only rarely been studied. Scots pine (Pinus sylvestris L.) stands were investigated in four locations in Lapland (northern Finland and northern Sweden, 67-68 degrees N) and in four locations in Estonia (59 degrees N) to test the hypothesis that plasticity in needle longevity results in similar needle biomass per foliated shoot length across latitudes. The needle-trace method (NTM) revealed the dynamics of needle fascicles attached to stem shoots. Long-term mean needle age was 2 years greater in Lapland than in Estonia. In both regions, mean needle age was strongly and negatively related to yearly needle-fascicle production rate relative to the number of needles on the same shoot axis. Although significantly fewer needle-fascicles were produced annually in trees in Lapland than in Estonia, the overall number of fascicles attached to the stem shoots, needle-fascicle density and individual needle dry mass did not differ between regions. Consequently, needle biomass per foliated shoot length was similar in trees in both regions. Thus, our results support the theory that plasticity in needle longevity helps Scots pine to compensate for reduced needle production so that the same foliar biomass per shoot is retained under a wide range of growth conditions.     

Distemper vaccination of farmed fur animals in Finland

The most important farmed fur animal species in Finland are the American mink (Mustela vison), blue fox (Alopex lagopus), silver fox (Vulpes vulpes) and raccoon dog (Nyctereutes procyonoides); all are susceptible to canine distemper. The only distemper vaccines currently available are for mink, although they also have been used for fox and raccoon dogs in emergency situations. The efficacy in eliciting neutralizing antibodies and the safety of three mink-distemper vaccines were studied under field conditions with mink and silver fox. Two of the vaccines were also studied with raccoon dogs and blue fox. All three vaccines elicited a satisfactory antibody response in mink, whereas the response varied in the other species. No side effects were observed in any species tested. One of the vaccines was safe and immunogenic in all four species.     

A distinct endothelial cell recognition system that controls lymphocyte traffic into inflamed synovium

Lymphocytes are essential mediators of normal tissue inflammatory reactions and of pathologic tissue damage in, for example, rheumatoid arthritis and other autoimmune diseases. In a study of the mechanisms controlling lymphocyte entry into sites of inflammation from the blood, the function and specificity of lymphocyte-endothelial interactions were examined in inflamed joint tissue (synovium) from patients with rheumatoid arthritis. Synovial high endothelial venules (HEV) supported the binding of normal peripheral blood lymphocytes in vitro. The characteristics of this binding, which were similar to those of lymphocyte-HEV interactions controlling lymphocyte migration into organized lymphoid tissues, included a requirement for calcium ions, a dependence on metabolic activity, and a preferential adherence of circulating lymphocytes as opposed to immature thymocytes. However, the binding of lymphocytes to synovial HEV was not inhibited by a monoclonal antibody to lymphocyte receptors for lymph node HEV, and synovial HEV failed to bind either lymph node HEV-specific or mucosal HEV-specific B lymphoblastoid cells. The results suggest that a lymphocyte-endothelial cell recognition system that is distinct from such systems in organized lymphoid tissues directs the extravasation of normal lymphocytes as well as pathologically important effector cells into inflamed synovium.     

High genetic diversity at the inter-/intra-host level of Cherry leaf roll virus population associated with the birch leaf-roll disease in Fennoscandia

A viral epidemic associated with the Cherry leaf roll virus (CLRV) has emerged in Betula species in Fennoscandia, exhibiting quick and effective spread during the last 15 years. A population genetics approach is chosen in order to characterise the virus diversity and the sources of genetic variation aiming to investigate the epidemiology of the pathogen. In a CLRV population from Rovaniemi urban parks and a population that occurred after infecting young Betula seedlings with scions from the original Finnish trees, the genetic diversity is found to be remarkably high, mixed infections by CLRV variants from different phylogenetic groups are detected in single trees, while recombination is evidenced to occur. The estimated genetic variability is high and the CLRV haplotypes detected exhibit clear clustering and belong to different phylogenetic groups. The structure of the viral population reveals a pathogen with high evolutionary potential assumed to carry on its effective spread.