Autumn frost hardiness of Pinus sylvestris offspring from seed orchard grafts of different ages

Autumn frost hardiness of offspring from clones (originating from 66.0–68.8° N) in six southern (62° N) and one northern (66.5° N) Pinus sylvestris seed orchards in Finland, was evaluated. One‐year‐old seedlings derived from open pollinated grafts of young, intermediate, and fairly mature age, and natural stand seedlings, were artificially freeze tested. The northerly located orchard produced the least injured offspring. There were no significant systematic differences between age classes. Neither were there any indications of decreased freezing injury with later age classes. The family variance was significant in four orchards. The estimated injury levels of orchard offspring were, in general, closer to those of natural stands in the neighbourhood of the orchard than natural stands at the place of clonal origin. It is suggested that not only differences in mother clone hardiness but also clonal differences in pollen contamination rate caused the observed family variation.     

Root growth capacity and field performance of Pinus sylvestris and Picea abies seedlings

Correlations between root growth capacity (RGC), at the time of planting, and field performance were studied for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings. Before planting a gradient in seedling viability was generated through exposure to low root temperatures and different winter storage regimes. The hypothesis that high RGC values would improve field performance was to some extent verified for pine seedlings while no correlations could be registered for spruce. Reasons for these results are discussed.     

Genetic variation in the natural pollen cloud of pinus sylvestris: a study based on progeny testing

Seeds from open pollination of individual female stroboli on different days in June 1990 in a coastal clone archive of Pinus sylvestris (L.) in northern Sweden (latitude 63°39’ N) were used for a short‐term progeny experiment to study differences over time in the genetic composition of the background pollen. Analysis of progeny growth and cold acclimatization in artificial whole‐plant freezing tests suggested no genetic differences in the fertilizing pollen between pollination days. A clinal variation with the latitude of pollen origin was observed for reference progenies from fertilization with pollen of known geographical origin. Comparisons between open‐pollinated progenies and reference progenies indicate that the pollen cloud originated from approximately 1° latitude (based on height growth) or 1.5° latitude (based on freezing injury) north of the pollination site.     

Growth and survival of spontaneous provenance hybrids of Pinus sylvestris

Survival and growth were assessed for 17 provenance hybrids and three natural populations of Pinus sylvestris (L.) planted in three field trials in central and northern Sweden. Restricted to the high mortality site the 18‐year hybrid survival percentage increased by three units per degree north latitude and one percent per 100 m higher altitude of the mother. The hybrid height was less influenced by the geographical origin than hybrid survival. For both traits the natural populations were better than or equal to hybrids with the same geographical mean origin. The variance component of the mother was mostly 2–3 times larger than the provenance component. The effect of the grandmother was nonsignificant for both traits.     

Predicting anatomical maturity of Pinus sylvestris L. Seeds in northern Fennoscandia

The hypothesis tested was that it should be possible to predict maximum attainable level of anatomical maturity of Pinus sylvestris L. seeds, and thus the germination capacity, using only one x‐ray based sample value of anatomical potential (Ap) in combination with a time function. This sample should be taken after commencement and before cessation of embryo growth. Since this predictive model should be independent of temperature, it was validated by repeatedly collecting seeds from several localities with presumably different temperatures during ripening. Although the temperature sums differed between localities, the rate of increase in Ap was almost identical in August. According to multiple linear regression analysis, the highest coefficient of determination (0.81) was achieved if Ap values from collections made in August were used in the regression. The average absolute deviation for the different localities between actual and predicted maximum Ap was 2%, and the highest deviation 7.2%. Thus, it should be possible to make a good prediction of the maximum germination capacity as early as in August. The practical consequence of this is that cone collection and possible artificial ripening could be started very close to the optimal time. Furthermore, soil scarification could be done in seed tree stands before seedfall when high seed quality is predicted.     

Fluorescein diacetate as a viability stain for tree roots and seeds

Fluorescein diacetate (FDA) was tested as a viability stain for roots of green ash as well as for seeds of green ash and 10 other tree species. The viability level indicated by FDA staining of green ash roots agreed well with root growth potential results, bud condition assessment, and foliage browning measurements. In seed viability experiments, the FDA staining intensity of embryos was related to germination in 9 out of 11 species tested using a 30 minute stain incubation period. In the other 2 species, eastern hemlock and Scotch pine, embryo FDA staining intensity and germination were also similar, provided an 18 h stain incubation period was used. When two seedlots of differing viability were tested in each of white spruce, Douglas-fir, and pitch pine, significantly higher germination was reflected in significantly higher embryo FDA staining intensity. In Sitka spruce seed that was heat treated to produce a range of viabilities, the semilog plot of germination (log scale) and FDA staining intensity of the embryo (linear scale) had an r²= 0.95. Based on these preliminary results, FDA shows promise as a rapid viability stain for tree roots and seeds.     

Age and spatial structure of natural Pinus sylvestris stands in Latvia

Abstract

The age and spatial structure of six natural old growth Pinus sylvestris stands in Latvia were investigated, to attempt to identify retrospectively the past features of development. In each stand, one or two plots of size 200–900 m² were established. Tree locations were mapped, stem diameter was measured, and tree age was determined from cores or by counting branch whorls. Tree distribution was assessed by Ripley's K function. A clumped spatial pattern was shown for P. sylvestris younger than 100 years. The temporal patterns of establishment could be partly linked to favourable climatic periods. The major disturbance affecting pine stands along the coast was windblown sand, which partly buried some stems and probably affected the patterns of seedling recruitment and mortality. Disturbance caused by fire had a major role in determining the past regimens of mortality and establishment in dry stands located inland. The successful invasion during the last century of spruce in more mesic plots with a pine overstorey may be due to fire suppression.     

Simulation of the long-term effects of different strategies for precommercial thinning in Pinus sylvestris

The influence of the intensity and timing of precommercial thinning (PCT) on stand development and financial return was studied in Scots pine stands. Functions describing the early development of the stand structure after PCT were developed. The functions were based on 195 plots within 41 PCT experiments in Sweden. The dimension distribution of the established stand was estimated and used as input to the decision support system Heureka, to simulate the stand development until final felling. The studied treatments included PCT to 1000, 2000 and 3000?stems?ha^?1 at mean heights of 2, 4 and 6 m. Separate simulations were carried out for different site fertilities. Mean annual volume increment increased with increasing number of stems after PCT whereas the timing of PCT had only a small effect. The land expectation value (LEV) generally decreased with increasing mean height at PCT, primarily because of the increased cost of PCT. LEV decreased with increasing number of stems after PCT at low fertility sites whereas only minor differences were found for PCT to 1000 and 2000?stems?ha^?1 at medium and high fertility sites. The general pattern persisted when different scenarios of future timber quality were simulated.     

Induction of hairy and normal roots on Picea abies,Pinus sylvestris and Pinus cortorta by agrobacterium rhizogenes

Two‐ to three‐week‐old seedlings of Picea abies, Pinus sylvestris and Pinus contorta were inoculated with the supervirulent strain Agrobacterium rhizogenes R1600 2cm above the base of the hypocotyl; other treatments included inoculation with Agrobacterium tumefaciens strain A281 (pTVK291) or mock inoculation. Hairy or highly branched roots formed on 2–3% of seedlings of all 3 species that were infected by R1600 but on none of the other seedlings. Normal adventitious roots were also induced on 5–10% of Agrobacterium‐treated seedlings but none appeared on the other seedlings. Opine assays and growth rates of hairy and normal roots indicated that only roots with the hairy morphology were transformed.     

Frost tolerance of various Pinus pure species and hybrids

Pinus species are widely planted by the South African forestry industry and are utilised for pulp, paper and saw timber products. Historically, Pinus patula Schiede ex Schltdl. et Cham. was the most widely planted commercial species in the summer rainfall area, but has come under severe threat due to the fungus Fusarium circinatum. Fusarium circinatum causes mortality in nurseries and in-field after establishment. Other Pinus species, such as P. tecunumanii F.Schwerdtf. ex Eguiluz et J.P.Perry and P. oocarpa Schiede ex Schltdl., have been crossed with P. patula to increase tolerance to F. circinatum and these hybrids have largely overcome the post-planting mortality problem. However, these hybrid-partner species are more prone to frost damage. This study reviewed laboratory screening techniques to assess the frost tolerance level of a range of Pinus pure species and hybrids. In vitro screening was done with the electrolyte leakage and whole-plant freezing techniques. Seedlings and rooted cuttings from a range of genotypes, supplied by Sappi, were tested in vitro at different target temperatures (?3, ?6, ?9 and ?12 °C) to determine their relative frost tolerance. These genotypes included a range of Pinus pure species, four interspecific hybrids (P. patula × P. tecunumanii low elevation [LE], P. patula × P. tecunumanii high elevation [HE], P. elliottii Engelm. × P. caribaea Morelet), and a three-way cross (P. patula × (P. patula × P. oocarpa)). Results from this study indicated that the electrolyte leakage technique was a reliable method to determine frost tolerance under laboratory conditions, with similar pure species rankings as experienced under field conditions. The interspecific hybrids of P. patula × P. tecunumanii LE and HE ranked intermediate between the parental species and the P. patula × P. tecunumanii HE hybrid was more frost tolerant than the P. patula × P. tecunumanii LE hybrid.     

Tocopherols,tocotrienols and fatty acids as indicators of natural ageing in Pinus sylvestris seeds

Abstract

During long-term storage, Scots pine (Pinus sylvestris L.) seeds are susceptible to ageing, leading to declined vigour and poor germinability. To characterize biochemical changes associated with this ageing, vitamin E and fatty acid compositions of Scots pine seeds stored for 3–31 years were analysed. The seeds contained seven homologues of the vitamin E family: α-, β-, δ- and γ-tocopherols (T) and α-, δ- and γ-tocotrienol (T3). The major tocopherol was γ-T, constituting on average 62.1% of total vitamin E. Total vitamin E concentration was markedly lower in older seeds, e.g. 21-year-old seeds contained 52% less vitamin E than the reference for high-quality seed. The α-T concentration was affected the most by seed age, whereas the γ-T concentration decreased more gradually and the concentrations of the other E vitamers seemed to remain relatively constant during natural ageing. Ageing also induced changes in the fatty acid composition of the seeds, e.g. a 29.6% reduction in the unsaturation/saturation ratio. These biochemical changes were associated with decreased germinability and increased electrolyte leakage.     

Changes in Ectomycorrhizal Colonization and Root Peroxidase Activity in Pinus sylvestris Nursery Seedlings Planted in Forest Humus

Plant biomass, root colonization by ectomycorrhizal (ECM) fungi and root peroxidase (POD) activity were monitored in Scots pine (Pinus sylvestris L.) nursery seedlings during the first growing season after planting (after 4, 8 and 16 weeks, in July, August and October, respectively) in forest humus in outdoor open-top chambers with gaseous atmospheric pollutants (combinations of low levels of ozone, sulfur dioxide and nitrogen oxides). The number of ECM morphotypes as well as root biomass increased towards the end of the growing season, while root POD activity decreased. Fungal biomass estimated as ergosterol concentration peaked in August, 8 weeks after planting. The seedling growth, mycorrhizal status and POD activity in the roots were not affected by the gaseous pollutants.     

Research versus operational correlations between seedling survival and root growth potential of shortleaf pine

Relationships between root growth potential (RGP) and plantation survival were evaluated for 12 families of shortleaf pine (Pinus echinata Mill.) from Oklahoma and Arkansas in 2 consecutive years. Bare-root, 1+0 seedlings were either planted one day after lifting (nonstored) or were stored at 1° to 3°C for 4 weeks. Correlations were obtained using the traditional research method where seedlings are planted in the field prior to obtaining results from the RGP test. In addition, operational correlations were derived by planting seedlings after obtaining RGP test data.For nonstored seedlings, research correlations were generally higher (r values were larger in 18 of 24 cases) than operational correlations. The predictive ability of operational correlations may not be high enough with 28-day pot tests to warrant batch culling of freshly lifted shortleaf pine. However, results were mixed for stored seedlings. In one year, operational correlations were generally higher than research correlations.     

Timing and intensity of precommercial thinning in Pinus sylvestris stands

The effects of timing and intensity of precommercial thinning were studied in three Scots pine artificially regenerated stands on Vaccinium forest sites in southern Finland. A two-level factorial design (3×3) was used in each stand: thinning at dominant height of 3, 6 and 9 m to 1000, 1600 and 2200 stems ha^?1. The effects of the treatments were analysed after a period of 23–25 yrs when the dominant height was 14–15 m. Early thinning resulted in the highest standing volume and amount of merchantable wood, and also in slightly accelerated height development. Thinning to 1000 stems ha^?1 caused a considerable production loss, but there were no differences between the densities of 1600 and 2200 stems ha^?1. Branches became thicker after early thinning, but the differences between the treatments were negligible for crop trees. Crown ratio was lowest as the result of early or moderate thinning (2200 stems ha^?1).     

The effect of different levels of green pruning on the diameter growth of Pinus sylvestris L.

It was hypothesized that maximum living crown removal can be determined from experimental data using linear statistical models. Pruning experiments were carried out in four Scots pine (Pinus sylvestris L.) stands. Zero to nine living branch whorls were removed in three stands in southern Finland, and 0–4.5 m of the living crown was removed in a stand in northern Finland. Only dead branch whorls were removed from the control trees. A total of 517 trees were analyzed. Diameter increment was measured five years after pruning. The growth reduction was statistically significant when 40% or more of the living crown was removed by pruning. According to the linear models, green pruning decreased diameter growth by 0 to 33% at defoliation levels below 40%. This loss in diameter growth is, from an economical point of view, compensated by the knotfree timber resulting from pruning 2–3 years earlier.     

Late Autumn Frost Resistance of Twelve North European Provenances of Quercus Species

Twelve north European oak provenances [11 Quercus robur L. and one Quercus petraea (Matt.) Liebl] were tested for late autumn frost hardiness using visual methods and measurements of relative conductivity. Tissue from buds and twigs from 2-yr-old seedlings was used. The test was carried out in November and December. Temperatures between ?20 and ?32°C were necessary to cause serious damage to tissue, even when tissues were tested only a few weeks after leaf fall. Visual methods proved to be fast and could be applied in practical test applications. Estimation of twig viability was found to be a more reliable variable than bud assessment, which appears to be sensitive and not necessarily related to plant mortality. Relative conductivity is a more labour-intensive method and requires some technical equipment, but it provided the most consistent statistical results. Strong correlation between the visual methods and relative conductivity was demonstrated. Provenances originating from locations close to the Atlantic ocean (The Netherlands, the UK, Denmark and Norway) tended to be less frost resistant than more continental provenances (from Norway, Sweden, Finland and Poland). Frost tolerance was correlated with budset, but not with growth of the provenances. The results confirm the existence of specific ecotypes and suggest a high potential for adaptation in Q. robur.     

Seedling shoot,needle and bud development in three provenances of Pinus sylvestris and Pinus contorta cultivated in northern Sweden

The patterns of current‐year shoot, needle and terminal bud elongation in seedlings of three Scots pine (Pinus sylvestris L.) and three lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) provenances were compared during the third and fourth growing seasons after planting. Lodgepole pine produced longer shoots and buds than did Scots pine, mainly because lodgepole pine formed more stem units and elongated at a faster rate. Stem unit length and the duration of shoot and bud elongation differed relatively little between species and provenances. Lammas or polycyclic growth occurred in some lodgepole pine provenances, but not in any Scots pine provenance, and was associated with enhanced shoot elongation. Needle elongation commenced earlier, proceeded at a faster rate, and was greater in lodgepole pine than in Scots pine, but ceased about the same time in all species and provenances. The heat sum required to attain 50% of final length was lower for shoots and needles in lodgepole pine than in Scots pine, and for shoots in northern provenances than in southern ones. Mitotic activity in the apical meristem of the terminal bud, which occurred less than one week after the seedlings were free from snow, started and ceased about the same time in each species, but was higher in lodgepole pine than in Scots pine early in the shoot elongation period.     

Influence of soil scarification on reindeer foraging and damage to planted Pinus sylvestris seedlings

Abstract

The effects of soil scarification on reindeer lichen cover and re-establishment, reindeer foraging and damage possibly caused by reindeer to planted Scots pine seedlings were studied during six growing periods in a field experiment established in a reindeer lichen site that was grazed by a herd of 500–600 reindeer each winter. Seedlings (at a density equivalent to 2000 ha^?1) were planted in mounds with mineral soil on top, in tracks with exposed mineral soil, in tracks with mixed organic material and mineral soil and in intact lichen mat (control) with no soil disturbance. The disturbed area varied from 0 to 28%. After six growing periods, the reindeer lichen cover and volume were 10–20% lower in the scarified plots than in the control plots. There was no clear evidence that the reindeer avoided foraging even in plots with the highest levels of soil disturbance. However, the behaviour of the reindeer during winter grazing seemed to be affected by both coverage of reindeer lichen (positively) and the proportion of exposed mineral soil (negatively). Damage possibly caused by reindeer trampling affected 8.2% of the living seedlings each year and approximately 50% of these seedlings were subsequently infected by fungal diseases (compared with 20% of viable undamaged seedlings). Scarification treatments that exposed mineral soil mildly resulted in higher survival and growth rates than the other treatments, especially the control.     

Development and transferability of two multiplexes nSSR in Scots pine (Pinus sylvestris L.)

Single sequence repeat(SSR) multiplexing is a semi high-throughput PCR methodology for the analysis of multiple SSRs.We developed two SSR multiplexes selected from SSR loci previously reported in the pine literature and tested the transferability of both SSR multiplexes in nine other pine species.We tested 234 nuclear SSR loci(n SSRs) previously described in the pine literature and selected ten n SSRs following the simple criteria of interpretability and reproducibility.Selected nuclear loci were divided into two n SSRs multiplex sets and their amplification was optimized for three different multiplex PCR methods based on:(a) a custom PCR protocol,(b) a custom protocol with hotstart taq polymerase,and(c) a commercially available kit for SSR multiplexing.To validate their performance,the level of genetic diversity was assessed in three Scots pine natural populations(Hungary,northern Sweden and southern Sweden).In addition,we also tested the transferability of these multiplexes in nine other pine species.We have developed two n SSRs multiplexes of five loci each that will contribute to reduce the costs of n SSR scoring,while increasing the capacity of n SSR loci analysis.Amplification was successful in all three populations(94 % success) and the level of polymorphism(7.1 alleles/marker) was similar to that previously reported for other Scots pine natural populations.Transferability of both multiplexes was successful for those pine species closely related to Scots pine.     

One-hundred-year foliage comparison of Pinus ponderosa and Pinus sylvestris under dry growing conditions in Brandenburg,Germany

Abstract

The dynamics of six different needle parameters of Pinus sylvestris L. and Pinus ponderosa Dougl. ex P. & C. Laws. were examined retrospectively for a 112-year-old mixed stand in Brandenburg, Germany, using the needle trace method. Similarities were found in needle production, needle loss and needle density. However, needle age, needle retention and total number of needles revealed significant differences between the tree species, with higher values for P. ponderosa. Pinus ponderosa yielded approximately twice as much mean whole-crown needle dry mass as P. sylvestris. Furthermore, different branching systems could be detected between the species, with both pines following “Corner's rule”. The results suggest that under identical growing conditions, P. ponderosa exhibits more efficient water use and can therefore maintain a bigger crown (as the basis for increased growth) than P. sylvestris.