Kari Mikkola

On the abundance of epiphytic green algae in relation to the nitrogen concentrations of biomonitors and nitrogen deposition in Finland

Green algae have become considerably more abundant in the years 1985–1995 in Finland and their distribution area has expanded northwards. Green algae on conifers were most abundant in southern Finland where the nitrogen deposition is highest. Correlations were observed between the abundance of green algae and a modelled nitrogen and sulphur deposition as well as the nitrogen concentration of the biomonitors. The increased abundance of green algae in Finland may be caused by several concurrent changes which have taken place in the environment and which have all promoted the occurrence of green algae. A slight rise in mean annual temperature, the long-term stability of nitrogen deposition, and the clear fall in the amount of sulphur deposition have probably all increased the growth and abundance of green algae. At a local level, the differences in microclimate have also effect on the abundance of green algae and the microclimate varies, inter alia, by the nutrient-richness of the habitat, the predominant tree species, stand age and stand density.

Concentrations of Foliar Quercetin in Natural Populations of White Birch (Betula pubescens) Increase with Latitude

We investigated latitudinal and regional variations in the composition and concentrations of foliar flavonoids and condensed tannins in wild populations of white birch (Betula pubescens EHRH) in a large climatic transect in Finland. Concentrations of quercetin derivatives were correlated positively with latitude. By contrast, the concentrations of apigenin and naringenin derivatives were correlated negatively with latitude. These compound-specific latitudinal gradients compensated each other, resulting in no changes in the concentration of total flavonoids. Our results thus demonstrate a qualitative, but not quantitative, latitude-associated gradient in the foliar flavonoids in white birch. Due to higher antioxidant capacity of the quercetin derivatives in relation to other flavonoids, the qualitative change can reflect higher adaptation to light in the north than south. An investigation on a regional scale in the northern boreal zone showed that the temperature sum was correlated positively and soil P concentration was correlated negatively with the concentrations of foliar flavonoid, while the concentration of condensed tannins was correlated with slope. The variation in concentrations of flavonoids at large-scale geographical patterns is in line with the conjecture that foliar flavonoids are synthesized for protection against photooxidative stress.

Compositional gradients in the forest vegetation of Finland

. Compositional gradients of forest vegetation in Finland were determined using detrended correspondence analysis, and ecologically interpreted with regression analysis. The data were collected in association with the 8th National Forest Inventory, and they comprised 1514 samples and 472 species, covering the whole forested land area of Finland. In the ordination space the first, very stable axis (DCA1) was much stronger than the following three, more unstable axes (DCA2 - 4). Site fertility (reflected by the forest site type series) and latitude had strongest covariation with the ordination space, followed by a number of variables primarily related to forest age or tree stand volume. Fertility variables were most closely parallel with DCA1, latitudinal ones with DCA1 and DCA2, and successional variables with DCA3. The results indicate that compositional overlap of sites classified into different Caj ander site types is considerable.

Modeling the Location of the Forest Line in Northeast European Russia with Remotely Sensed Vegetation and GIS-Based Climate and Terrain Data

Abstract GIS-based data sets were used to analyze the structure of the forest line at the landscape level in the lowlands of the Usa River Basin, in northeast European Russia. Vegetation zones in the area range from taiga in the south to forest-tundra and tundra in the north. We constructed logistic regression models to predict forest location at spatial scales varying from 1 × 1 km to 25 × 25 km grid cells. Forest location was explained by July mean temperature, ground temperature (permafrost), yearly minimum temperature, and a Topographic Wetness Index (soil moisture conditions). According to the models, the forest line follows the +13.9°C mean July temperature isoline, whereas in other parts of the Arctic it usually is located between +10 to +12°C. It is hypothesized that the anomalously high temperature isoline for the forest line in Northeast European Russia is due to the inability of local ecotypes of spruce to grow on permafrost terrain. Observed patterns depend on spatial scale, as the relative significance of the explanatory variables varies between models implemented at different scales. Developed models indicate that with climate warming of 3°C by the end of the 21st century temperature would not limit forest advance anywhere in our study area.

Mapping of the epiphytic lichens on conifers in Finland in the years 1985–1986 and 1995

Abstract A systematic mapping of thirteen epiphytic lichen species on conifers was carried out in Finland at the first time in 1985–1986 and the second time in 1995. The aim of mapping work was to describe the regional distribution of the most common epiphytic lichens and to assess air quality based on the abundance of epiphytic lichens. All lichen species demonstrated increases in their abundance between the years 1985 and 1995. Scoliciosphorum chlorococcum , a species tolerant to air pollution, increased most in parts of the southern Finland where the nitrogen levels are relatively high. This indicate increased levels of nutrients in the forests. On the other hand, sensitive lichen species had become more common particularly in the central parts of the country, which is in agreement with decreasing sulphur deposition. The climate, tree species, stand age etc., however, mainly determining the distribution and the abundance of epiphytic lichens in Finland.

Epiphytic Lichens on Conifers in the 1960’s to 1980’s in Finland

The frequencies of three lichen species or genera have been studied in litter samples from seven permanent litterfall collection plots located in different parts of the country. The frequencies of pollution-sensitive Usnea and Bryoria species have decreased between 1967 and 1985 in the southernmost sample plots, while the frequency of fairly tolerant Hypogymnia physodes has remained stable.

Forest Management and Regeneration Success in Protection Forests near the Timberline in Finnish Lapland

Sustainable forestry is practised in Finnish Lapland north of latitude 69°, i.e. farther north than anywhere else in the world. The Protection Forests Act was passed in 1922 to guarantee the stability of timberline forests in this climatically extreme, unique area. This review, based on earlier studies, covers forest and climate statistics, and legislation, regulations and recommendations of forest management, and the effects of management practices and climatic trends on the results of natural and artificial regeneration of conifer forests, as well as on shifts in the timberline. The review is mainly based on Finnish research, but references from the other Fennoscandian countries have also been used. Temperature plays the main role in forest regeneration success, and the effective temperature sum has been found to express well the location of the Scots pine (Pinus sylvestris L.) timberline. Natural regeneration of pine has been satisfactory, especially when combined with soil preparation. In many cases the pine forests regenerate in the form of advance growth without any silvicultural action. The success of artificial regeneration seems to be associated with favourable, warm periods lasting for at least 20 yrs. The effects of cutting, forest fires, reindeer herding, biotic damage and air pollution on forest regeneration and the conifer timberlines are discussed.

The Vitality of Conifers in Finland, 1986–88

Regional distribution in the vitality of Scots pine and Norway spruce was assessed in Finland in three consecutive years, 1986–1988. The condition of a total of 3600 trees on systematically selected 450 permanent, mineral soil sample plots was surveyed using needle loss and the number of needle age classes as vitality indicators. Abundance of branch damage and secondary branches were also recorded in 1988.

Spatial distribution of dead wood and the occurrence of five saproxylic fungi in old-growth timberline spruce forests in northern Finland

Abstract Adequate understanding of the factors that determine the establishment and survival of dead-wood-dependent species in natural forests is a prerequisite to the successful maintenance of these species in managed forests. This study investigated the factors affecting the occurrence of five wood-inhabiting polypores in old-growth timberline spruce forests in northern Finland, including the substrate availability and the spatial arrangement of large-diameter logs. The volume of coarse woody debris (CWD) varied significantly between the sites (range 15–30 m3 ha−1), large-diameter logs comprising on average 35% of the total CWD volume. However, the within-site variation in CWD volume was 10–15 times larger than the between-site variation. The spatial distribution of large-diameter logs was aggregated or initially aggregated on four sites and random on one site, creating local patches of high CWD volume. An individual target species occurred on average on 8% of all large-diameter logs, and on 11% of optimal logs (as determined by the decay stage). The characteristics of the logs and stand variables explained partly the occurrence of the target species; furthermore, the mortality pattern of trees (stem breakage versus uprooting) and the presence of primary decomposers also significantly affected the occurrence of the target species. The results indicate that besides substrate availability and quality, local habitat factors and species interactions also play a role in the occurrence of wood-inhabiting fungi in boreal timberline forests.

Soil acidity status in polluted and non‐polluted areas in southern Finland

From 359 study plots on coniferous forest soil in southern Finland, 232 humus and 359 mineral soil (top 5 cm) samples were taken in 1991 and analyzed for their cation exchange capacity, base saturation, pH, total S content (humus samples only), and extractable Al, Fe, and Mn concentrations in order to assess the impact of acidic air pollution on soil acidity. The main sources of local air pollutants (SO2 and NOX) were from the capital region and an oil refinery. Although concentrations of S in the humus layer were 8% higher near the emission sources, it was concluded that air pollution has not resulted in a detectable increase in soil acidity. Mean values for humus layer pH (BaCl2), cation exchange capacity (CEC), base saturation, and extractable Al concentration for the overall study area were 2.9 (0.2), 310 (50) meq kg‐1, 48 (12)% of CEC, and 530 (340) mg kg‐1. The respective values for the mineral soil layer were 3.3 (0.3), 56 (19) meq kg‐1, 13 (8)% of CEC, and 320 (130) rngkg‐’. Standard deviations ar...