Drought effects on water use efficiency, freezing tolerance and survival of Eucalyptus globulus and Eucalyptus globulus × nitens cuttings

Genetic improvement of Eucalyptus genotypes for drought and frost resistance is essential for successful intensive management of commercial plantations. Understanding the physiological mechanisms that relate water use and frost resistance for highly deployed genotypes may allow for better prediction of their future performance, genetic selection and seedling management for site specific purposes. We studied whether instantaneous water use efficiency (WUE _i ) may serve as drought, freezing and photoinhibition tolerance predictor by studying its response on six E. globulus clones (Eg1–Eg6) and four E. globulus × E. nitens hybrid seedlings (Egn1–Egn4) under drought and irrigated (control) treatments. Net photosynthesis (A) and transpiration (E) were studied using a gas exchange system in order to calculate WUE _i (A/E). Simultaneous chlorophyll a fluorescence measurements were performed to assess the non photochemical quenching components. Frost tolerance of plants under control and drought treatments were evaluated by measuring temperatures that exert 50% photoinactivation of photosystem II. Finally, drought tolerance was evaluated by plant survival within each genotype after rehydration. Our results showed significant genotype variability in the rate of soil and xylem water potential decrease during drought. While most of the genotypes reached ?4.0 MPa in about 35 days of drought, genotypes Eg6 and Egn4 required 56 days of drought to reach this xylem water potential. WUE _i exhibited significant differences among genotypes and irrigation treatments. Genotypes Eg5 and Egn4 increased their WUE _i between 70 and 80% after drought. This was associated with a more conservative control of water loss at the stomatal level combined with maintenance of relatively higher rates of net photosynthesis than the other genotypes under drought conditions. Plants exposed to drought were more freezing tolerant than control plants, having in average 3°C lower LT₅₀ than well irrigated ones. There was no a clear correlation between WUE _i and drought tolerance or drought-induced photoinhibition, however WUE _i was inversely correlated with LT₅₀. Our results suggest that WUE _i is not suitable by itself to select drought tolerant genotypes, but may provide evidence for discarding drought sensitive genotypes. In addition, it could provide valuable information to select for freezing tolerance.     

Fungi occurring in the roots and basal parts of one‐ and two‐year‐old spruce and pine stumps

The occurrence of fungi in the underground parts of 1‐ and 2‐year‐old conifer stumps (Pimis sylveslris and Picea abies) was studied in two clear‐felled areas of eastern Uppland in Sweden, and most fungal isolates were identified to species.

Decay fungi (Basidiomycetes) were more frequent in spruce stumps than in pine stumps, and their incidence was highest in 2‐year‐old stumps. The occurrence of blue‐stain fungi and hyaline mycelia did not differ significantly between stumps of different species or age. Within stumps, decay fungi were most frequent in large roots close to the cut surface, whereas blue‐stain fungi and hyaline mycelia were most abundant in small roots. The occurrence of yeasts, bacteria and fast‐growing moulds was also recorded.     

The effects of test environments on estimation of genetic parameters for seedling traits in 2‐year‐old Douglas‐fir

The effects of test environments (dry versus wet) on estimation of genetic parameters in seedling traits were studied in 160 open‐pollinated families of Douglas‐fir (Pseudotsuga menziesii (Mirb.) Franco) from southwestern Oregon. Seedlings from four populations were grown in two test environments for two growing seasons. Between test environments, ‐9 bars of water potential difference were created in both growing seasons. Estimated genetic variances in most growth and phenology traits were considerably higher for seedlings grown in the wet environment than for those in the dry. Estimated genetic correlations between the same traits measured in different test environments indicated that most seedling traits studied for two growing seasons are genetically stable in both environments—i.e., suggesting that genotype by environment interaction in these traits are weak. However, the effect of test environment on estimation of genetic parameters in seedling traits, especially in adaptive seedling traits, should be evaluated very carefully when early evaluation of genetic entries is practiced in Douglas‐fir since these traits (budburst timing, lammas growth and free growth) appear to be plastic traits.     

Genetic variability of growth and wood chemical properties in a clonal population of Eucalyptus urophylla × Eucalyptus grandis in the Congo

Thirty-four Eucalyptus urophylla × Eucalyptus grandis hybrids were evaluated with a view to selecting for improved growth and wood-quality traits for plantations in the Congo. Height, circumference at breast height and volume were measured at 12, 27, 37, 49 and 60 months. Lignin content, the syringyl/guaiacyl ratio and total extractives content were predicted by near-infrared spectroscopy using wood powder samples collected from trees at breast height. While wood chemical properties were stable and under strong genetic control, growth traits were not. The genetic correlation between lignin content and growth was weak and negative, whereas the environmental correlation was also weak but positive. The genetic improvement of E. urophylla × E. grandis clones, based on growth features, leads to a limited decrease in lignin content and syringyl content and to a limited increase in extractives content.     

Within‐ and Between‐population Variation of Growth and Stem Quality in a 30‐year‐old Pinus sylvestris Trial

In a combined population‐progeny experimental plantation of Pinus sylvestris at Nordanås, lat. 64°19’ long. 18°12’ alt. 400 m, a few growth characters and around 25 quality characters were meaured or assessed at age 34 from seed. The populations under study originated from latitudes 63–67. The experimental design is a split‐plot with three replications. Each population is represented by 10–20 open pollinated progenies planted in 15‐tree row plots at a spacing of 2.5x2.5 m. All growth and most quality characters showed significant population differences. Family differences were noted for approximately half of the quality characters. The family repeatability for growth and quality characters varied much between the populations in a non‐consistent way. Thanks to the strong genetic correlations between breast height diameter and stem volume, as well as between tree height and stem volume those two characters could be used to estimate stem volume.     

Long‐term effects of liming on the fine‐root standing crop of Picea abies and Pinus sylvestris in relation to chemical changes in the soil

The long‐term effects of lime application on fine roots of Norway spruce, Picea abies (L.) Karst, and Scots pine, Pinus sylvestris (L.), have been studied in five experimental forest stands subjected to different lime applications 5 to 18 years before the present study was undertaken. The effects of liming does not seem to significantly influence fine‐root development in forest stands in the long term. The only response to liming in measured root variables was a tendency to increased specific root length (SRL = fine‐root length/fine‐root dry weight, m/g). A correlation between increased SRL, decreased root biomass and increased stem volume growth was indicated. Changes in water extractable amounts of mineral elements—P, K, Ca, Mg, Mn, S, Al and Fe‐in bulk soil and rhizosphere soil from the mineral soil layers were studied in a control area and an area treated with 3830 kg CaCO₃ ha^‐1. Few significant differences were found between treatments, and then mainly in the case of Ca.     

Dominant species’ resprout biomass dynamics after cutting in the Sudanian savanna-woodlands of West Africa: long term effects of annual early fire and grazing

Background   

The potential of forest to regenerate after harvesting is a key element for sustainability of the ecosystem. For semi-arid tropical savanna environments, managing resprouts after tree cutting is ideally suited because of the natural ability of many indigenous species to regenerate vegetatively. Regeneration in this ecosystem is, however, prone to many disturbance factors such as fire and grazing by livestock.     

Effects of chemical sterilization of the culture media,porous membranes and luminosity on in vitro culture of Eucalyptus grandis×Eucalyptus urophylla

Hybrid combinations of Eucalyptus have increased due to expansion of plantations into unconventional areas and to the search for higher quality timber.However,most of these species have difficulties surviving in vitro cultivation.Active chlorine and sealing systems are often used to reduce contamination and increase gas exchange.The aim of the present study is to evaluate the establishment,multiplication,elongation and adventitious rooting of E.grandis × E.urophylla.Two clones(C1 and C2) and four active chlorine concentrations(0.000%,0.001%,0.003%,and 0.005%) were tested in the establishment and multiplication phases.Three sealing forms(W/M,1/M and 3/M) and the same four active chlorine concentrations were applied to the elongation phase.Two luminosities(dark and light)and three sealings(W/M,1/M and 3/M) were tested during adventitious rooting.Active chlorine concentration of0.005% led to the lowest fungal contamination rate and to the highest in vitro establishment.Active chlorine concentration of 0.003% resulted in the greatest length and highest number of shoots per explant in the multiplication phase.There were no phytotoxicity problems and the quality of plants grown in an environment with active chlorine was maintained in comparison with those grown in an autoclave.The increase in gas exchange in ventilation systems had a positive impact on the in vitro growth and development of plants.     

Autumn temperature affects the induction of dormancy in first‐year seedlings of acer platanoides L.

First‐year seedlings of five latitudinal populations of Acer platanoides were subjected to decreasing photoperiod treatment under three different temperature regimes. The depth of the induced dormancy was quantified as the number of days to bud burst (DBB) under defined conditions favourable to growth. The results suggested a close relationship between autumn temperature and the strength of the induced dormancy, with high temperatures combined with short days leading to a deeper stage of dormancy. Northern and continental populations generally had bud burst earlier than southern. The results are discussed in relation to hypotheses for dormancy induction and release.     

The use and non‐use of economics and mathematics in forest economics. The Swedish experience 1876–1976

The paper surveys Swedes’ contributions to forest economics during a period of hundred years starting in 1876, when Carl‐Gustaf Holmerz's book “Studies in Forest Surveying”; was first published. This contains the correct solution to the problem of when to cut down an evenly aged forest stand, but the so‐called Swedish “profitability war”; could not be avoided. Gustaf Cassel's, Gunnar Myrdal's, Bertil Ohlin's, Sven Petrini's, and Thorsten Streyffert's contributions are discussed, as well as an until recently unpublished contribution by Knut Wickseil. The paper also shows how slowly the methods of positive economics were introduced in forest economics in comparison with the normative OR‐methods, and that econometric techniques have also been sparsely applied. A few outstanding exceptions are pointed out, e.g., the Ruist‐Svennilson estimates of timber supply functions published in 1949.     

Genetic variation,heritability and expected gain of height in Picea abies in 7 to 9‐year‐old clonal tests

Clonal material propagated as cuttings and control seedling lots of Norway spruce (P. abies [L.] Karst.) were compared in two series of clonal tests. Variance components, heritability and expected genetic gain were calculated for height based on measurements carried out in the tests at the age of seven and nine years. The mean heights of the clones were significantly higher than those of the controls in one of the test series, but there was no significant difference between these two groups in the other series. The variance due to clone sources was significant in both test series and accounted for 10 to 19% of the total variation. Broad sense heritabilities were 0.21 ± 0.05 and 0.23 ± 0.02 on the individual level and 0.75 ± 0.06 and 0.78 ± 0.02 on the basis of the clone mean for the respective series. Theoretical genetic gains were calculated based on the assumption that the tallest 10% of the clones would be selected and propagated for reforestation purposes. The expected gain in height was 13.1 and 19.1% in these test series. Utilization of this gain is, however, difficult due to the ageing of the clones.     

Stand and site characteristics in the decline of pinus sylvestris caused by gremmeniella abietina shoot disease in a severely damaged 50‐year‐old plantation in se lapland

The role of stand and site characteristics in a 50‐year‐old, sowed Scots pine (Pinus sylvestris L.) stand on the decline of Scots pine caused by Gremmeniella abietina was studied. Treewise damage of Scots pine was modelled using stand and site variables and stepwise regression analysis. The significant variables included in the model were stand elevation from the main cold air centre and the pH of the humus layer, while the other less significant variables were the number of stems per hectare of Scots pine and Norway spruce, content of Cu and Ni in the humus layer, and the thickness of the humus layer and the A₂ horizon. The studied variables excluded from the model were the number of broad‐leaved trees per hectare, Al and Pb contents in the humus layer, and Al, Cu, Pb and Ni contents in the A₂ horizon. The results strongly suggest that the vicinity of water as well as local depressions act as vulnerable sites for Scots pine and the said vulnerability is enhanced by increased pH of the humus layer.     

The effects of partial cutting on stand structure and growth of western hemlock–Sitka spruce stands in southeast Alaska

The effects of partial cutting on species composition, new and residual-tree cohorts, tree size distribution, and tree growth was evaluated on 73 plots in 18 stands throughout southeast Alaska. These partially cut stands were harvested 12–96 years ago, when 16–96% of the former stand basal area was removed.Partial cutting maintained stand structures similar to uncut old-growth stands, and the cutting had no significant effects on tree species composition. The establishment of new-tree cohorts was positively related to the proportion of basal-area cut. The current stand basal area, tree species composition, and stand growth were significantly related to trees left after harvest (p<0.001). Trees that were 20–80 cm dbh at the time of cutting had the greatest tree-diameter and basal-area growth and contributed the most to stand growth. Diameter growth of Sitka spruce and western hemlock was similar, and the proportion of stand basal-area growth between species was consistent for different cutting intensities.Concerns about changing tree species composition, lack of spruce regeneration, and greatly reduced stand growth and vigor with partial cuts were largely unsubstantiated. Silvicultural systems based on partial cutting can provide rapidly growing trees for timber production while maintaining complex stand structures with mixtures of spruce and hemlock trees similar to old-growth stands.     

Seasonal changes in contents of root starch and soluble carbohydrates in 4–6‐year old Betula pubescens and Popuius tremula

Roots of 4–6‐year old European aspen and pubescent birch were collected monthly during 1983–87 and 1983–88, and analysed to determine their starch, fructose and glucose concentration. Carbohydrate concentrations in aspen roots fluctuated with low levels in May‐June. Seasonal variation was not as consistent in birch roots as in aspen roots. The drop during May‐June occur as consistently in birch. Total carbohydrate concentrations in roots of birch collected from six latitudes (56–67°N) in Sweden showed similar patterns of variation. There were no significant difference between starch concentrations among roots of different diameters (2–11 mm), nor did concentrations differ between sites at different distances (5–25 cm) from the main stem. It was difficult to visually differentiate between low and medium starch levels. Some practical implications of the results are discussed     

The use of glyphosate for the management of secondary coppice regrowth in a Eucalyptus grandis × E. urophylla coppice stand in Zululand,South Africa

In South Africa, commercial eucalypt stands may be regenerated through the stepwise reduction of coppice shoots following felling. The development of secondary coppice regrowth following these reduction operations results in competition with the remaining stems, possibly resulting in a reduction in growth. Currently, secondary coppice regrowth is controlled manually, or through spraying with glyphosate at 0.6% when ca. 0.75?m in height. No research has been conducted to determine whether alternative rates and/or timing of application are possible or cost-effective. In 2006 a trial was implemented in Zululand, South Africa on a recently coppiced stand of Eucalyptus grandis × Eucalyptus urophylla so as to optimise rates of glyphosate application (0.6%, 1.2% and 1.8%) for the control of secondary coppice regrowth at various heights (0.5, 1.0 and 1.5?m). Tree and secondary coppice regrowth variates were measured annually until rotation-end (9 years, 3 months). The volume of herbicide used, the number of occasions each treatment was sprayed and associated costs were combined to provide an indication of the most cost-effective treatment. Although there were no significant differences in final coppice yield for the various rates of glyphosate and timing of application (as assessed by the size of the secondary coppice regrowth) tested, treatment efficacy in terms of treating secondary coppice regrowth increased with an increase in the rate of glypho- sate applied (0% < 0.6% < 1.2% < 1.8%), especially when treated at either 1.0 or 1.5?m in height. The use of glypho- sate, irrespective of rate and/or timing of application (as assessed by secondary coppice regrowth height), proved to be more cost-effective compared with manual control or the spraying of the secondary coppice regrowth at 0.75?m height with 0.6% glyphosate. The most cost-effective treatment was 1.2% glyphosate applied when the secondary coppice regrowth was 1.5?m. If reduced herbicide use is a major criterion within a company portfolio, then the secondary coppice regrowth can be manually removed when 1.5?m.     

Multiple‐use characteristics of Norwegian clearcuts: Using aerial photographs to digitize in three dimensions

Using aerial photographs and a PC (personal computer) based photogrammetric instrument, the author measured landscape features to characterize clearcuts in a “multiple‐use” forest of the outskirts of Oslo, Norway. One hundred and forty‐six clearcuts were examined for area and non‐timber features (such as buffer dimensions and residual vegetation). The results of three dimensional digitized data—captured directly off the stereophotos—created the profiles of clearcuts on private and public land. In addition, the application of PC‐based photogrammetry to natural resource management is discussed.     

Breeding and scientific advances in the fight against Dutch elm disease: Will they allow the use of elms in forest restoration?

New Forests - Elms (Ulmus spp.) were once dominant trees in mixed broadleaf forests of many European territories, mainly distributed near rivers and streams or on floodplains. Since ancient times...     

Spatial integration in the Nordic timber market: Long‐run equilibria and short‐run dynamics

This study presents an econometric analysis of the spatial integration of the Nordic timber market as reflected in timber prices. The statistical model is a vector autoregressive (VAR) model with cointegration. The degree of spatial integration is tested through a cointegration analysis and a complete identification of the statistical model's long‐run structure. When the results were interpreted in terms of factor price equalization and efficient commodity arbitrages, the Nordic markets were found to be strongly integrated. The pattern of interdependence is investigated through an analysis of the model's short‐run structure and interpreted in terms of Granger causality. Finland, and to some extent Sweden, were found to act as “price‐leaders” in the long run and Denmark and Norway were very sensitive to changes in timber prices in competing countries.     

Correction to: Breeding and scientific advances in the fight against Dutch elm disease: Will they allow the use of elms in forest restoration?

New Forests - Author had ordered for open access after the article went online in Springer link. The article was changed to open access article.     

Effects of selection cutting on the forest structure and species diversity of evergreen broa-leaved forest in northern Fujian, southern China

The short-term effects of selection cutting of different intensities on the forest structure and species diversity of evergreen broad-leaved forest in northern Fujian Province were investigated and analyzed. The results showed that selection cutting of low and medium intensities caused little variation in the forest structure. After cutting, the dominant species retained their leading status in the community. However, the community structure changed significantly following selection cutting of high and extra-high intensities; the status of the dominant species of the community declined dramatically. Some tree species began to disappear from the sampling plots. Except for extra-high intensity cutting, the diversity of tree species did not change significantly for the other three cutting intensities. However, the evenness of the stands was very different among the four kinds of cutting plots. For low and medium intensity selection cutting, the evenness declined slightly. For extra-high intensity selection cutting, the evenness increased to some extent, which might be due to a more even distribution of tree species after cutting. Cutting operations resulted in some adverse reactions to development of arborous species diversity of evergreen broad-leaved forest, particularly serious damage to the forest canopy. But the rational selection cuttings, which may benefit the restoration and maintenance of species diversity over a long period and may come about from the variations in environmental factors such as sunlight, temperature and humidity.