Current issue: 56(1)
Under compilation: 56(2)
Progenies from open pollinated cones collected in natural populations of Norway spruce (Picea abies (L.) Karst.) distributed along two altitudinal transects in Mid-Norway were tested in the nursery, in short term tests and in long-term field trials. The populations showed clinal variation related to the mean annual temperatures of the populations, with the earliest bud flush and cessation of shoot elongation and lowest height at age nine years for the high altitude populations. Within population variation was considerable as the narrow sense heritability for these traits was 0.67, 0.31 and 0.09 in one transect and 0.55, 0.18 and 0.14 in the other transect, respectively. Lammas shoots occurred in the short term trials with large variation in frequency between years. There was significant family variation for this trait, but also interactions between populations and year. The variance within populations was considerably larger in the populations from low altitude compared to the high-altitude populations. Significant genetic correlations between height and phenology traits and damage scores indicate that families flushing early and ceasing growth late were taller. Taller families also had higher frequencies of damages. Selection of the top 20% families for height growth in short term tests at age nine years gave a simulated gain of 11% increased height growth at age 18 years in long term trials at altitudes similar to those of origin of the populations. The gain was negative when high altitude populations were selected based on testing in the lowland.
Populations at species’ range margins are expected to show lower genetic diversity than populations at the core of the range. Yet, long-lived, widespread tree species are expected to be resistant to genetic impoverishment, thus showing comparatively high genetic diversity within populations and low differentiation among populations. Here, we study the distribution of genetic variation in the pedunculate oak (Quercus robur L.) at its range margin in Finland at two hierarchical scales using 15 microsatellite loci. At a regional scale, we compared variation within versus among three oak populations. At a landscape scale, we examined genetic structuring within one of these populations, growing on an island of ca 5 km2. As expected, we found the majority of genetic variation in Q. robur to occur within populations. Nonetheless, differentiation among populations was markedly high (FST = 0.12) compared with values reported for populations of Q. robur closer to the core of its range. At the landscape level, some spatial and temporal sub-structuring was observed, likely explained by the history of land-use on the island. Overall, Q. robur fulfils the expectation of the central-marginal hypothesis of high differentiation among marginal populations, but the notable population differentiation has most likely been influenced also by the long, ongoing fragmentation of populations. Finnish oak populations may still be adjusting to the drastic habitat changes of the past centuries. Preservation of genetic variation within the remaining stands is thus an important factor in the conservation of Q. robur at its range margin.
Vaccinium myrtillus L., Vaccinium uliginosum L. and Vaccinium vitis-idaea L. are perennial, cold-adapted clonal shrubs distributed throughout Europe, northern Asia and North America. Due to their usage in food (berries) and pharmaceutical industry (berries and leaves), their natural populations are exposed to anthropogenic and other impacts that affect their genetic make-up. We analyzed 14 fragmentary distributed and small-sized peripheral populations of these species from the Balkans, which represents the southeastern-European marginal area of their wide European distributions, using RAPD molecular markers. The contemporary genetic patterns in all three species within the Balkans were generally similar, and in comparison to previous reports on populations of these species found in northward Europe, where they have a more continuous distribution, the levels of genetic diversity were more or less halved, genetic differentiation was several times higher, gene flow exceptionally low, and the expected prevalence of clonal individuals was lacking. The population dynamics of all three species within the Balkans was complex and distinct, and was characterized by a past admixture of individuals from discrete populations of the same species and interspecific hybridisation not only between V. myrtillus and V. vitis-idaea but also between V. uliginosum and V. vitis-idaea, the latter not being reported to date. Conservation measures suitable for preservation of presumably genetically distinct portions of the Balkans’ gene pools of studied species have been suggested, while the utility of interspecific hybrids in breeding programs and/ or in food/pharmaceutical industry is yet to be assessed.
Dilution plate method was used in studying the density and composition of the microfungal populations of the organic layer of Scots pine forests, and the soil-plate method in studying the part of these populations decomposing cellulose. The media used were rose bengal agar (Martin’s medium for fungi) and cellulose medium.
The microfungal density depended to a considerable extent on the moisture content and temperature of the organic layer. Only the combination of relatively high moisture content and temperature, but neither of these factors alone, influenced considerably the microfungal population density. The correlation of the populations to the changes in this combined factor was stronger than the correlation to the seasonal variations of spring, summer and autumn.
The microfungal population consisted of only a few species. Mucor, Mortierella and Penicillium were the most common genera isolated from the rose bengal agar. The first and the last of these comprised almost 90% of the total population. For the Mucor fungi, increases in the moisture content up to the maximum values found (75%) were favourable; the Penicillium fungi, on the contrary, were intolerant of high moisture content.
Among the cellulose decomposing microfungi grown on cellulose medium, Trichoderma sp. was the most common; also, it formed the most colonies, tolerated the lowest temperatures, and was most efficient. The others were of the genera Pullularia, Verticillium, Scopulariopsis and Penicillium. In addition, there were some unidentified Phycomycetes fungi. Only the two first-mentioned caused observable changes in cellulose.
Genetic variation in 5 natural stands of Quercus robur L. in Finland was analysed electrophoretically for 13 isozyme loci. Stands were on average polymorphic at 49.2% of the loci, with 2.1 alleles per locus. Observed heterozygosities, ranging from 13.6% to 16.9%, were slightly lower than estimates reported for German stands. The majority of the species’ genetic variation was found within each studied stand, and only 5.5% was between stands. Mean genetic differentiation (∂) was the same as that found in the primary range of the species, but the differentiation estimates (D) for single Finnish population were more variable.
Studies of phenotypic as well as mixed population plasticities are urgently needed in a world that supposedly experiences a gradual change of its environment. It is important to understand that man creates his environment and silviculture. This is one of the reasons why for breeding it cannot be expected to find optimal phenotypes in nature. Other reasons are the phylogenetic constraints and migration of pollen and seeds.
Forest genetics up to now is characterized by the study of one trait at a time. There is an urgent need for simultaneous analysis of several traits by the aid of genetic correlations or multivariate analysis. Generally there is a need for inclusion of larger numbers of genetic entries in forest genetic investigations.
For the long-rotation-time species there is a need to determine the curves for degree of dormancy and hardiness during the annual cycle. Information of plasticity in two-dimensional environments like water availability and temperature is needed. Studies on nutrient utilization and acquisition will tell us whether or not we must have different breeding populations for different soil fertilities. An understanding of the phase changes between juvenile and adult opens up possible applications such as faster generation turn-over in the breeding population via early flowering and early testing as well as better plants for frost-prone and weedy sites.
Pair numbers of breeding land birds were estimated from line transects data collected in Finland in 1936–76. The changes observed in the bird populations are in this paper compared with data obtained in the Finnish forest inventories, particularly made in 1951–53 and 1971–76. It is concluded that modern forestry has considerable impact on the breeding bird fauna. In general, more species have increased than decreased due to changes in the forests. Areas affected by forestry are more favourable habitats for many species than natural forests, but, on the other hand, there are certain species which are greatly harmed by the effects of modern forestry.
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