Matti Haapanen

Genetic host-tree effects on the ectomycorrhizal community and root characteristics of Norway spruce

A greenhouse experiment was used to study the effects of host genotype on short root formation and ectomycorrhizal (ECM) fungal community structure in Norway spruce (Picea abies (L.) Karst.). Rooted cuttings representing 55 clones were inoculated with a mix of vegetative hyphae of five ECM fungal species (Laccaria sp., Amphinema byssoides, Piloderma sp., Cadophora finlandia, Paxillus involutus). After one growing season, the ECM fungal community structure was determined by amplifying the fungal internal transcribed spacer (ITS) of ribosomal DNA directly from ECM root tips. Restriction profiles of obtained amplicons were then compared to those of the inoculated strains. Spruce clones differed in their ECM fungal community composition; we found a statistically significant clone-specific effect on ECM fungal diversity and dominating fungal species. Nevertheless, the broad sense heritabilities of the levels of Laccaria sp., Piloderma sp. and A. byssoides colonisations as well as the ECM fungal community structure were low (H2 = 0.04−0.11), owing to the high within-clone variation. As nitrogen concentration of needles correlated negatively with ECM fungal richness, our results imply that in the experimental conditions nutrient acquisition of young trees may benefit from colonisation with only one or two ECM fungal species. The heritability of short root density was moderate (H2 = 0.41) and highest among all the measured shoot and root growth characteristics of Norway spruce cuttings. We suggest that the genetic component determining root growth and short root formation is significant for the performance of young trees in natural environments as these traits drive the formation of the below-ground symbiotic interactions.

Endophyte communities vary in the needles of Norway spruce clones

Endophytic fungi show no symptoms of their presence but can influence the performance and vitality of host trees. The potential use of endophytes to indicate vitality has been previously realized, but a standard protocol has yet to be developed due to an incomplete understanding of the factors that regulate endophyte communities. Using a culture-free molecular approach, we examined the extent to which host genotype influences the abundance, species richness, and community composition of endophytic fungi in Norway spruce needles. Briefly, total DNA was extracted from the surface-sterilized needles of 30 clones grown in a nursery field and the copy number of the fungal internal transcribed spacer (ITS) region of ribosomal DNA was estimated by quantitative PCR. Fungal species richness and community composition were determined by denaturing gradient gel electrophoresis and DNA sequencing. We found that community structure and ITS copy number varied among spruce clones, whereas species richness did not. Host traits interacting with endophyte communities included needle surface area and the location of cuttings in the experimental area. Although Lophodermium piceae is considered the dominant needle endophyte of Norway spruce, we detected this species in only 33% of samples. The most frequently observed fungus (66%) was the potentially pathogenic Phoma herbarum. Interestingly, ITS copy number of endophytic fungi correlated negatively with the richness of ectomycorrhizal fungi and thus potential interactions between fungal communities and their influence on the host tree are discussed. Our results suggest that in addition to environmental factors, endophyte communities of spruce needles are determined by host tree identity and needle surface area.

Genetic relationships between growth and quality traits in an 8‐year‐old half‐sib progeny trial of Pinus sylvestris

Genetic correlation was employed to study heritable covariation among sixteen growth and quality traits in a progeny trial of Scots pine (Pinus sylvestris L.). Phenotypic correlations and heritability values for each trait were also presented. The expected correlated response of the quality traits to mass selection for a single growth trait was studied on the basis of these parameters. Generally, tree height was found to be more closely related to stem quality than diameter or volume. The correlations between growth traits and relative branch and crown traits were mainly favourable with regard to breeding. The heritability values were moderate and relatively similar for both quality and growth traits. Genetic and phenotypic correlations appeared to be considerably analogous, especially when the latter were computed on the family‐mean level.

Effect of southern pollination on the survival and growth of seed orchard progenies of northern Scots pine (Pinus sylvestris) clones

Abstract The growth and survival of background pollinated progeny of northern Scots pine clones from seed orchard located in southern Finland was examined at an age of 10–15 years and compared with the respective performance of seedlings from local natural stands. The material consisted of 33 progeny tests located in northern Finland within the original areas of the clones. Although no clear difference was observed between the height growth of the two groups, the survival was significantly lower in the seed orchard material (35%) than in the local stand material (56%). The relative survival (seed orchard vs. local entries) decreased steadily along with the decrease in the effective temperature sum of the trial sites, and was relatively small in the northernmost trials. The results indicate that the totally background pollinated seed from southwards-transferred, young seed orchards even can be used for reforestation in southern and central Lapland, at least in areas located at relatively low altitudes. The decrease in background pollination levels owing to the ageing of these orchards will increase the potential use of this seed. Using only those orchards containing the northernmost clones, combined with selective harvesting of the most hardy portion of the clones, is proposed as a means of further improving the adaptedness of planting material for northern conditions.

The genetic and economic gains from forest tree breeding programmes in Scandinavia and Finland

ABSTRACT Plantations of genetically improved forest trees are critical for economic sustainability in forestry. This review summarizes gains in objective traits and the resulting economic impact of tree breeding programmes in Scandinavia and Finland. Genetic improvement of forest trees in these countries began in the late 1940s, when the first phenotypically superior plus-trees were selected from natural environments. The main findings from this review are that (i) tree breeding can increase volume growth in the range 10–25%, and (ii) the bare land value associated with genetically improved trees gives a better return on investment and a shorter rotation period compared to the unimproved forests. As some Nordic countries are quite dependent on the forest industry, breeding programmes that have resulted in economic gains have been beneficial for society. Growth and wood quality traits are often adversely correlated, and the weighting of traits from an economic perspective could provide an index for determining maximum profit from breeding. Tree breeding faces an array of challenges in the future, such as changes in silviculture, climate, new pests and diseases, and demand for wood-based products.

Genetically improved reforestation stock provides simultaneous benefits for growers and a sawmill, a case study in Finland

ABSTRACT Recent research has demonstrated benefits of genetically improved seed material (from seed orchards) for growers. In this study, we analyzed whether the profits of genetically faster growing material are also realized as simultaneous economic benefits for a sawmill. We compared three types of improved Scots pine (Pinus sylvestris L.) seedlots to unimproved seedlots on three climatically different sites using stand-simulation software MOTTI. Genetic gains in early-rotation growth traits were incorporated in the growth models as genetic multipliers. Bare land values of the simulated stands were maximized using stand-level optimization. Consequently, removals of each thinning and final harvest were used to estimate the total value of sawing yield. This was subsequently maximized by optimizing the sawing procedure of the logs assuming identical timber quality between improved and unimproved seedlots. The results indicate that simultaneous financial incentives from tree breeding are achievable for both agents (growers and a sawmill). In general, the financial potential increases with the growth potential of the regeneration material, although the form of the relationship is not linear in all cases.