The large pine weevil (
) is a major regeneration pest in commercial forestry. Pesticide application has historically been the preferred control method, but pesticides are now being phased out in ...several countries for environmental reasons. There is, thus, a need for alternative plant protection strategies. We applied methyl jasmonate (MeJA), salicylic acid (SA) or oxalic acid (OxA) on the stem of 2-year-old Norway spruce (
) plants to determine effects on inducible defenses and plant growth. Anatomical examination of stem cross-sections 9 weeks after application of 100 mM MeJA revealed massive formation of traumatic resin ducts and greatly reduced sapwood growth. Application of high concentrations of SA or OxA (500 and 200 mM, respectively) induced much weaker physiological responses than 100 mM MeJA. All three treatments reduced plant height growth significantly, but the reduction was larger for MeJA (~55%) than for SA and OxA (34-35%). Lower MeJA concentrations (5-50 mM) induced comparable traumatic resin duct formation as the high MeJA concentration but caused moderate (and non-significant) reductions in plant growth. Two-year-old spruce plants treated with 100 mM MeJA showed reduced mortality after exposure to pine weevils in the field, and this enhanced resistance-effect was statistically significant for three years after treatment.
•Radial xylem sap flow profiles are rarely studied, especially under abiotic stress.•A beech/spruce forest was exposed to repeated seasonal drought and recovery.•HFD and TD type sensors were applied ...to measure the xylem sap flow density profile.•Repeated drought reduced the xylem sap flow profile in spruce but not in beech.•Radial sap flow profiles are altered by drought-induced leaf area reductions.
Water consumption of trees is one of the most important processes connected to their survival under ongoing climate change and extreme events such as drought. Radial profiles of xylem sap flow density are an integral component to quantify the water transport for the level of an individual tree and that of ecosystems. However, knowledge of such radial profiles, in particular under stress, is very scarce. Here we show the radial profile of the xylem sap flow density in mature European beech (Fagus sylvatica L) and Norway spruce (Picea abies (L) Karst.) under repeated summer drought induced by throughfall exclusion (TE) and subsequent recovery compared to untreated control trees (CO). We measured xylem sap flow density (udaily in L dm−2 d−1) down to 8 cm sapwood depth at breast height using two different approaches, a thermal dissipation system and the heat field deformation method. In beech, repeated throughfall exclusion did not affect the radial xylem sap flow profile. However, in spruce, udaily was strongly reduced across the profile under repeated drought, changing the profile from a linear to a logarithmic regression. Even two years after drought release, the xylem sap flow profile did not fully recover in TE spruce. The reduction of udaily along the radial profile was accompanied by a reduction of the leaf area in TE spruce by c. 50%, while sapwood depth remained constant. The reduction of the xylem sap flow density along the profile reduced the calculated water consumption of TE spruce trees by more than 33% compared to CO trees, also after drought release. The impact of stressors such as repeated drought on the xylem sap flow density across the radial profile and its consequences for trees’ and stands’ water consumption needs to be addressed in more detail to minimize uncertainties in quantifying ecosystem water cycles.
The study of xylogenesis or wood formation is a powerful, yet labor intensive monitoring approach to investigate intra-annual tree growth responses to environmental factors. However, it seldom covers ...more than a few growing seasons, so is in contrast to the much longer lifespan of woody plants and the time scale of many environmental processes. Here we applied a novel retrospective approach to test the long-term (1926-2012) consistency in the timing of onset and ending of cambial activity, and in the maximum cambial cell division rate in two conifer species, European larch and Norway spruce at high-elevation in the Alps. We correlated daily temperature with time series of cell number and lumen area partitioned into intra-annual sectors. For both species, we found a good correspondence (1-10 days offset) between the periods when anatomical traits had significant correlations with temperature in recent decades (1969-2012) and available xylogenesis data (1996-2005), previously collected at the same site. Yet, results for the 1926-1968 period indicate a later onset and earlier ending of the cambial activity by 6-30 days. Conversely, the peak in the correlation between annual cell number and temperature, which should correspond to the peak in secondary growth rate, was quite stable over time, with just a minor advance of 4-5 days in the recent decades. Our analyses on time series of wood anatomical traits proved useful to infer on past long-term changes in xylogenetic phases. Combined with intensive continuous monitoring, our approach will improve the understanding of tree responses to climate variability in both the short- and long-term context.
•Data from even- and uneven-aged spruce stands used to assess response to cuttings.•A stand basal area growth model predicted cutting responses without bias.•Growth rate of uneven-aged stands was 20% ...lower than in even-aged stands.•Growth response to cuttings was notably quicker in even-aged spruce stands.
This study evaluated the basal area growth of Norway spruce stands subjected to different management strategies; specifically, even-aged (EA) stands treated with thinning from below and uneven-aged (UEA) stands treated with selective cutting. Analysis was based on extensive empirical data obtained from permanent long-term experiments established in 23 even-aged and 26 uneven-aged Norway spruce (Picea abies (L.) Karst.) stands in Southern and Central Finland. The specific goals were to determine whether there are differences in: (a) the relationship between the stocking level and the stand basal area growth, (b) the stand basal area growth rates at a given stocking level, and (c) the stand basal area growth responses to cuttings between EA and UEA stands.
A model-based approach was adopted in the analysis. Modelling was used to describe general trends and patterns in the data, emphasising the effects of overall stand density, cutting intensity, and management strategy on post-treatment stand growth. A model for a stand basal-area growth was fitted as a mixed linear model to the pooled data from EA and UEA stands. Model simulations were conducted to elucidate how the treatment of stands affects the predicted stand basal area growth.
The analysis revealed a clear general effect of stocking level on stand basal area growth for all data. Growth increased with increasing stocking density. There was a significant difference in the stand basal area growth of EA stands and UEA stands. The growth of UEA stands was ca. 20% smaller than that of EA stands. There were also major differences in the timing and magnitude of the growth response to cutting between EA and UEA stands. Post treatment growth was noticeably slower in UEA stands than in EA stands, especially during the first 10 years after cutting. The results clearly show that the growth response of the trees remaining in EA stands is faster and greater than that in UEA stands, enhancing the stand basal area growth.
► Barks of Norway spruce and Scots pine have a significant content of extractives. ► Both barks fractionated well by milling and with similar fraction yield profile with a low proportion of fine ...particles. ► The fractions with the smaller particle size concentrated higher amounts of inorganic material and of extractives. ► Milling and particle size separation may be used in bark utilization as pretreatment for selective enrichment or reduction of targeted components and applications.
The composition of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) barks was studied after grinding and fractioning into different particles sizes.
Both barks fractionated well and with similar fraction yield profile. The yield of fines was low and the major fractions were larger particles, i.e. 2.4% and 3.1% of particles under 0.425mm and 66.0% and 50.3% of particles over 2mm, respectively for spruce and pine bark.
The chemical composition of spruce and pine barks, as a mass weighed average of all granulometric fractions was, respectively: ash 3.3 and 4.6%; total extractives 21.6 and 18.8% (hydrophilic extractives were dominant), lignin 27.9 and 33.7% and holocellulose 42.7 and 37.6%. Suberin accounted for 1.3% and 1.6% of spruce and pine bark, respectively. The non-cellulosic monosaccharides showed in both barks predominance of arabinose followed by xylose and mannose.
Ash elemental composition showed that N represented about 35% of the total inorganics, Ca 35% and K 17%. Zn, Cu, Ni, Cr and Pb were present in both barks at levels under 1% of the total inorganics. Spruce bark had in average higher contents compared to pine bark, except for Pb and Cr.
Size reduction of spruce and pine bark did not apply randomly to the different components and instead resulted into partial separation of the inorganic and organic matter into different size particles. Fine particles concentrated higher amounts of inorganic material and of extractives.
Exposure of Norway spruce (
) somatic embryos and those of many other conifers to post-maturation desiccation treatment significantly improves their germination. An integration analysis was conducted ...to understand the underlying processes induced during the desiccation phase at the molecular level. Carbohydrate, protein and phytohormone assays associated with histological and proteomic studies were performed for the evaluation of markers and actors in this phase. Multivariate comparison of mature somatic embryos with mature desiccated somatic embryos and/or zygotic embryos provided new insights into the processes involved during the desiccation step of somatic embryogenesis. Desiccated embryos were characterized by reduced levels of starch and soluble carbohydrates but elevated levels of raffinose family oligosaccharides. Desiccation treatment decreased the content of abscisic acid and its derivatives but increased total auxins and cytokinins. The content of phytohormones in dry zygotic embryos was lower than in somatic embryos, but their profile was mostly analogous, apart from differences in cytokinin profiles. The biological processes "Acquisition of desiccation tolerance", "Response to stimulus", "Response to stress" and "Stored energy" were activated in both the desiccated somatic embryos and zygotic embryos when compared to the proteome of mature somatic embryos before desiccation. Based on the specific biochemical changes of important constituents (abscisic acid, raffinose, stachyose, LEA proteins and cruciferins) induced by the desiccation treatment and observed similarities between somatic and zygotic
embryos, we concluded that the somatic embryos approximated to a state of desiccation tolerance. This physiological change could be responsible for the reorientation of Norway spruce somatic embryos toward a stage suitable for germination.
Tree rings have been reliably used as an environmental proxy over the past decades for environmental reconstructions, simulations and forecasting. In our study, we investigated whether tree-ring ...chronologies are impacted by pollution. We chose sites in the Krušné hory and the Krkonoše Mountains in the Czech Republic which have a known history of pollution. We sampled Norway spruce (Picea abies L. Karst) in both ranges and compared their chronologies. We found no significant difference in the overall radial growth in the chronologies from both regions. However, we observed an increased heterogeneity in the growth of trees from the 1970s till the 1990s. Coherently, a severe reduction in tree growth from the late 1970s and a recovery towards the early 1990s was evident. We collected and analysed soil samples for pH and exchangeable element concentrations. All seven sampling sites' soils were strongly acidic (pHCaCl2 = 3.3 ± 0.4). The average soil base saturation at Krušné hory was higher than at Krkonoše (39% versus 12%), likely due to more intensive liming.
Further, we compared these chronologies to other sites in Europe. Analysing 89 sites, we found that most (9 out of 14) of the sites with significantly reduced radial tree growth were located within the former ‘Black Triangle’, an area which was subjected to heavy industrialisation and pollution from the 1960s to the 1990s. Atmospheric sulphur deposition was found to negatively affect radial tree-growth, while limited quantities of oxidised nitrogen appeared to have a positive effect. Our results are consistent with previous research, indicating that atmospheric SO2 pollution and subsequent acid fog and rime have led to a reduction in annual radial tree growth across the Black Triangle.
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•1.Spruce from the Czech Republic show significantly reduced growth from 1970s till late 1990s.•2.Soils at all sampled sites were severely acidic (pH 2.5 to 4) impacting the tree growth.•3.Reduced tree growth could be due to airborne translocation of pollution.•4.Spruce growth from the Black-Triangle region is more impacted than in Western Europe.
A genomic selection study of growth and wood quality traits is reported based on control-pollinated Norway spruce families established in 2 Northern Swedish trials at 2 locations using exome capture ...as a genotyping platform. Nonadditive effects including dominance and first-order epistatic interactions (including additive-by-additive, dominance-by-dominance, and additive-by-dominance) and marker-by-environment interaction (M×E) effects were dissected in genomic and phenotypic selection models. Genomic selection models partitioned additive and nonadditive genetic variances more precisely than pedigree-based models. In addition, predictive ability in GS was substantially increased by including dominance and slightly increased by including M×E effects when these effects are significant. For velocity, response to genomic selection per year increased up to 78.9/80.8%, 86.9/82.9%, and 91.3/88.2% compared with response to phenotypic selection per year when genomic selection was based on 1) main marker effects (M), 2) M + M×E effects (A), and 3) A + dominance effects (AD) for sites 1 and 2, respectively. This indicates that including M×E and dominance effects not only improves genetic parameter estimates but also when they are significant may improve the genetic gain. For tree height, Pilodyn, and modulus of elasticity (MOE), response to genomic selection per year improved up to 68.9%, 91.3%, and 92.6% compared with response to phenotypic selection per year, respectively.Subject Area: Quantitative genetics and Mendelian inheritance.
Somatic embryogenesis is being piloted for the commercial production of genetically improved Norway spruce (
L. Karst) forest regeneration material in Finland. The main challenge to making the ...process commercially relevant is the dependence on time-consuming and highly skilled manual labor. Automation and scaling up are needed to improve cost-effectiveness. Moving from the proliferation of embryogenic tissue on semisolid media to suspension cultures could improve process scalability. In a series of four experiments (overall, with 20 cell lines, 4-9 per experiment), the suitability of proliferation in suspension culture for Norway spruce somatic embryogenesis was evaluated based on the growth rate, indicators of stress conditions, good-quality cotyledonary embryo yield, and embling survival in a greenhouse. The proliferation rate in suspension was found equal to on semisolid media, but with a remarkable genotypic variation. Embryogenic tissue matured directly without pre-treatments from suspension onto semisolid media produced lower numbers of good-quality embryos than tissue matured from semisolid media. Rinsing the suspension-grown tissue with hormone-free liquid media before maturation improved embryo yield, bringing it closer to that of semisolid-grown tissue. Decreasing 6-benzylaminopurine and 2,4-dichlorophenoxyacetic acid concentrations in suspension proliferation media to 0.5 or 0.1 times those in semisolid media did not affect tissue growth and did not improve embryo production. The hydrogen peroxide (H
O
) content and guaiacol peroxidase activity were elevated in suspension cultures compared with semisolid medium, which had the same plant growth regulator content. In one experiment out of four, the greenhouse survival of germinants was lower when proliferation was carried out in full strength suspension than on semisolid media; in other experiments the survival rates were equal.
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