Erkki Annila

Estimating risks for spruce bark beetle (Ips typographus (L.)) damage using pheromone‐baited traps and trees

The risk for damage associated with spruce bark beetle attacks on living trees was estimated in 12 forest districts in the Nordic countries during three years. Pheromone‐baited traps and trees were used. Five groups of three traps were deployed annually on fresh spruce clear‐fellings in each district. The mean catches within districts and years ranged from 950 to 46000 beetles per trap group. The standard error averaged 15 % of the mean catch. One tree was baited annually at each of five other sites in each district. The mean number of trees colonized by Ips typographus in each district and year ranged from 0 to 5 per site. The standard error was high, averaging 44% of the mean. Inventories of tree mortality within the districts yielded values ranging from 0 to 150 killed trees per km of spruce forest edge. There was a strong linear correlation between mean catches in traps and log‐transformed tree mortality (r=0.82). The correlation between colonization success at tree‐baiting sites and tree mortality wa...

Tree Mortality, Needle Biomass Recovery and Growth Losses in Scots Pine Following Defoliation by Diprion pini (L.) and Subsequent Attack by Tomicus piniperda (L.)

Tree mortality and growth losses following insect defoliation are poorly documented in Scandinavia. In 1990-1991, Diprion pini (L.) caused extensive defoliation to Scots pine in Lauhanvuori national park and surrounding areas in south-western Finland. Most trees lost all their foliage in 1990. In 1991, the outbreak area was sprayed with diflubenzuron (Dimilin®), except in the national park, where trees were severely defoliated again. No further defoliation occurred in 1992. In spring 1993, sprayed trees had ca 30% foliage, whereas unsprayed trees on average carried less than 10% of full foliage. The latter trees were susceptible to attack by Tomicus piniperda (L.), whereas the former largely escaped beetle attack. Beetle attacks peaked in 1993, and depletion of suitable host trees probably terminated the beetle outbreak in the area. Two years of severe defoliation resulted in substantial tree mortality and growth losses. In spring 1997, these unsprayed stands had suffered a ca. 50% loss in basal area which was mainly because of mortality, and about half of the dead trees had been attacked by T. piniperda. Surviving trees had ca 50% of full foliage, and radial growth had still not recovered. Basal area growth was reduced by 40-70%, depending on the amount of foliage left after the second year of defoliation. In contrast, tree mortality and beetle attack in the sprayed stands were negligible, and these trees had recovered full foliage and radial growth by spring 1997. Thus, one year of total defoliation resulted in an estimated loss in basal area growth of approximately 30% during ca. 5 yrs. In conclusion, the spraying operation was economically justified, as it prevented substantial tree mortality and reduced growth losses.

Why did life emerge

Many mechanisms, functions and structures of life have been unraveled. However, the fundamental driving force that propelled chemical evolution and led to life has remained obscure. The second law of thermodynamics, written as an equation of motion, reveals that elemental abiotic matter evolves from the equilibrium via chemical reactions that couple to external energy towards complex biotic non-equilibrium systems. Each time a new mechanism of energy transduction emerges, e.g., by random variation in syntheses, evolution prompts by punctuation and settles to a stasis when the accessed free energy has been consumed. The evolutionary course towards an increasingly larger energy transduction system accumulates a diversity of energy transduction mechanisms, i.e. species. The rate of entropy increase is identified as the fitness criterion among the diverse mechanisms, which places the theory of evolution by natural selection on the fundamental thermodynamic principle with no demarcation line between inanimate and animate.

Vitality and bark beetle resistance of fertilized Norway spruce

Abstract The effects of different so-called vitality fertilizers on the resistance of Norway spruce against back beetles and their associated pathogenic fungi were studied in field experiments. Stem diameter growth, phloem phenolic concentration, resin flow, and reaction to inoculation with Ceratocystic polonica were measured on the trees. The fertilization treatments increased stem diameter growth, but did not affect resin flow, phloem phenolic concentration, or the lesion length caused by the blue-stain fungus. Thus, contrary to expectations based on current theories, we could demonstrate no functional relationship between growth and defence. However, the number of resin canals correlated positively with tree vigour, and there were indications of a potential increase in this constitutive defence feature after fertilization. Resin flow increased two-fold in the trees wounded 1 year earlier, indicating an induced component in resin production. This induced mechanism was unaffected by fertilization. Thus, although it does not seem possible to markedly increase either the constitutive or the inducible resistance level of Norway spruce through fertilization, vitality fertilization did not reduce the defences in our study and we hypothesize that it can be used without endangering resistance.

Effects of vitality fertilization on the resin flow and vigour of Scots pine in Finland

The vitality and defence of Scots pine were measured in order to study how different fertilizer combinations affect these traits, and to determine whether an increase in growth leads to reduced defence as predicted by the theories based on the assumption of the existence of a trade-off between growth and carbon-based defence compounds. Stem diameter growth and vigour index were measured as indicators of vitality and stem resin flow and the concentration of phloem phenolics were used as indicators of defence level. Fertilizer treatments containing nitrogen had a growth-promoting effect and the vigour index was higher in the nitrogen-fertilized treatments than in the control and non-nitrogenous fertilizer treatments. Four of the ten experimental sites were situated along a heavy metal pollution gradient at 0.5, 2.5, 4 and 8 km distance from the emission source. The vigour index in the severely polluted site closest to the emission source was considerably lower than that in the other three sites along the gradient, but even there nitrogen gave a clear growth response. In spite of the large within- and between-tree variation in resin flow, the average resin exudation differed little between the experimental sites. In most sites the resin flow was highest in the control treatment. A weak negative correlation was found between resin flow and vigour index. In the pollution gradient the mean resin flow was lowest at the most polluted site and increased along the gradient up to 4 km from the emission source. The phenolic concentration of the phloem was not affected by fertilization in any of the experiments apart from the severely polluted one. Indications of a weak negative linear correlation between vigour index and phloem phenolics were found. There was no significant correlation between the phenolic concentration and the amount of resin flow in any of the different sites. Except for the liming treatment in the polluted experiments, we did not detect any response to non-nitrogenous fertilizer treatments.

Soluble carbohydrates, radial growth and vigour of fertilized Norway spruce after inoculation with blue-stain fungus, Ceratocystis polonica

Abstract. The aim of this study was to determine whether fertilization and the consequent increase in growth reduce the allocation of soluble carbohydrates in response to an induced wound. Norway spruce trees fertilized with N, P or NPK were artificially infected with Ceratocystis polonica, a blue-stain fungus associated with the spruce bark beetle Ips typographus. N and NPK fertilization treatments increased radial growth of the stem and the vigour indices. The concentration of total soluble carbohydrates in the outer border of the lesion was significantly decreased in P-fertilized trees compared to corresponding unfertilized trees. However, changes in the soluble carbohydrate concentration caused by fungal inoculation were more pronounced than changes caused by fertilization. The main soluble carbohydrate was sucrose, and after fungal inoculation its concentration decreased considerably near the site of inoculation. Thus, near the site of fungal inoculation the concentration of total soluble carbohydrates also decreased significantly compared to corresponding values in unwounded phloem. Despite the fact that in all fertilized trees the radial growth of the stem increased, the only indication that enhanced growth might reduce the level of resistance was the modest positive correlation between lesion length and radial growth of the stem.

Breeding efficiency in Tomicus piniperda and shoot damage after late autumn thinning of young Pinus sylvestris stands

The breeding of the pine shoot beetle (Tomicus piniperda) after thinning of young Scots pine stands in late autumn, and subsequent shoot damage, were studied in southern, central and northern Finland during three successive years (1977–79). No distinct increase in the attack density or beetle population was observed on the felled trees during the study period. Shoot damage on the standing trees remained low, and was not considered to have any marked negative effect on tree growth or further development of the pine stand. No noticeable difference was found between the different parts of the country. The economic importance of beetle damage resulting from late autumn thinnings was estimated to be low.

The significance of sex

Sexual and asexual modes of proliferation are associated with advantages and disadvantages, yet a profound percept that would account for both ways of reproduction is missing. On the basis of the 2nd law of thermodynamics we find that both sexual and asexual reproduction can be regarded as a means to consume free energy in least time. Parthenogenesis is a fast way to consume a rich repository of free energy, e.g., an ample stock of food with a large number of individuals, whereas sexual reproduction is a fast way to consume diverse and dispersed resources with a large variety of individuals. Most organisms have adapted to their surroundings accordingly and some organisms switch from one mode of reproduction to the other depending on the amount and dispersion of free-energy sources. We conclude that the least-time free energy consumption in respective surroundings, as the general criterion of natural selection, determines also sexual and asexual modes of reproduction.