Response of juvenile Norway​ spruce (Picea abies [L.] Karst.) to ectomycorrhizal inoculation of perlite-peat substrates in a nursery

Nursery growth substrate and ectomycorrhizal symbiosis are important circumstances influencing seedling development. In this study, the effect of pre-sowing inoculation of pure peat and peat+perlite mixtures (2:1 and 1:1, v:v) with an ectomycorrhizal mycelium-bead inoculum prepared in the laboratory and commercial inoculum Ectovit on ectomycorrhiza formation, growth, and foliar nutrients concentration of 1-year-old bare-root Norway spruce seedlings was estimated. Seedlings grown in the substrates inoculated with bead inoculum had significantly larger shoot dry weight and slightly higher other growth parameters than those grown in non-inoculated and Ectovit-inoculated substrates. However, the use of inocula formed neither treatment-specific ectomycorrhizal morphotypes nor higher mycorrhization of roots compared to control. Ectomycorrhizae were most probably formed by naturally occurring fungi; nevertheless, based on the abundance of the morphotypes, any participation of the applied fungi in ectomycorrhiza formation and/or their non-nutritional effects is not excluded. Seedlings grown in peat+perlite (2:1) mixture were slightly higher-developed than those in the two other substrates, but significant effect of the substrates neither on seedling growth nor on ectomycorrhiza formation was detected. In all treatments, sufficient macroelements concentration in needles was found. The results suggest difficulties to reach a complex positive effect of ectomycorrhizal inoculation in operational conditions and its dependence on various circumstances.     

Distribution of biomass and carbon in even‐aged stands of Norway spruce (Picea abies (L.) Karst.): A case study on spacing and thinning effects in northern Denmark

The main objective of this case study was to explore the possible influence of forest management on the levels and distribution of biomass and carbon (C) in even-aged stands of Norway spruce [Picea abies (L.) Karst.] in Denmark. Data originated from a long-term thinning experiment and an adjacent spacing experiment at stand ages of 58 and 41 years, respectively. Biomass of 16 trees from different thinning and spacing treatments was measured or partly estimated, and soils were sampled for determination of C stocks. All trees in each plot were measured for stem diameter and some for total height, to allow for scaling-up results to stand-level estimates. For trees of similar size, foliage biomass tended to be higher in the spacing experiment, which was located on slightly more fertile land. Foliage biomass increased with increasing thinning grade, but the effect could not be separated from that of tree size. At stand level, foliage biomass tended to increase with increasing spacing as well as with increasing thinning grade. For branchwood, stems and roots (including below-ground stump), the biomass increased with increasing tree size and stand volume at tree and stand level, respectively, but no differences between stands, spacings or thinning grades were observed, apart from that expressed by tree size or stand volume. At stand level, C stocks of all biomass compartments decreased with increasing thinning grade, while the distribution between compartments was hardly influenced. The ratio between above-ground and stem biomass was about 1.21 at stand level, while the ratio between below- and above-ground biomass was about 0.17. Thinning influenced the C stock of the forest floor and mineral soil oppositely, resulting in no effect of thinning on total soil C.     

Improving estimations of maximal stand density by combining Reineke’s size-density rule and the yield level, using the example of spruce (Picea abies (L.) Karst.) and European Beech (Fagus sylvatica L.)

? The Reineke Stand density rule relating stem numbers to the quadratic mean diameter is generally used as a reference for modelling maximal stand density.

? The linearity of this relationship after double logarithmic transformation is generally assumed, but it must be questioned for untouched stands and stands with a conventional thinning regime. Curvilinearity is demonstrated for some spruce and beech stands in Switzerland and shown to be statistically representative. This relationship is independent of the site index. It can be interpreted as a change in mortality in young stages mainly due to competition and in older stages more to ageing.

? A more accurate estimation of the maximal stand density needs to take into account the important variation around the mean course, known as the yield level. A simple method to assess the yield level of any stand regardless of whether it is thinned or not is presented, based on estimating the effect of a stand opening on the basal area.

     

An approach to determining forest areas with recreational potential: The case of forest areas around main transportation roads in the Maçka Region of Trabzon,Turkey

It is most important to determine areas with recreation potential that can permit sustainable use of forest resources and also meet recreational uses. Under the method described in this study, using the Geographic Information System (GIS), a spatial suitability model for recreational use was combined with a recreational priority perceptual suitability model that depends on principal component analysis (PCA) and is based on the perceptions of both recreational users and experts. Using principal component analysis, five priority components explaining 69.371% of the total variance were identified out of 12 perceptual suitability components. These components are scenic beauty, accessibility, the surface of the landscape, tree type, and forest stand condition. The recreation terrain suitability value of an area with recreational potential was assessed with the assistance of these five priority components. This enabled us to generate a recreation terrain suitability value equation and a recreation terrain suitability value scale for a potential recreation area. This applicability of this approach was demonstrated in the identification of potential recreation areas in Trabzon, Turkey.     

Light quality and intensity of light-emitting diodes during pre-cultivation of Picea abies (L.) Karst. and Pinus sylvestris L. seedlings – impact on growth performance,seedling quality and energy consumption

Three different LED lamps with continuous spectra were compared against commonly used fluorescent lights. The lamps were characterized by light output, energy consumption and spectral quality for plant growth. The biological effects of light quality were compared by pre-cultivating seedlings of Picea abies (L.) Karst. and Pinus sylvestris L. under each spectrum for 35 days in a growth chamber with controlled temperature, humidity and photoperiod. The seedlings were then transplanted and cultivated for one vegetation period at the nursery, then planted outdoors on a forest field trial and followed for three years. The seedlings showed similar growth performance for all spectra tested. LED lamps have several advantages to fluorescent light such as energy consumption, longer life span and adjustable light intensity. Regarding light intensity the effects on growth performance were studied for both species using the most promising LED spectra. The photosynthetically active radiation (PAR) was maintained at 50, 100, 200 and 400 μmol?m^?2?s^?1. Unlike energy consumption, seedling development did not display a linear relationship to light intensity. Instead, the results show an optimum light level between 100 and 200?μmol?m^?2?s^?1 for the shade tolerant Picea abies seedlings and a level of around 200?μmol?m^?2?s^?1 for the more shade intolerant Pinus sylvestris seedlings.     

Genetic aspects of age dynamics of a natural Picea abies (L.) Karst. population in the Białowieża Primeval Forest, Poland

We studied temporal changes in the genetic structure and diversity of a naturally regenerated Picea abies (L.) Karst. (Norway spruce) population in the Bia?owie?a Primeval Forest, Poland. The analysis included five age classes of trees: newly germinating seedlings (in laboratory conditions), seedlings up to 3 years old, young trees 4–10 years old, middle-aged trees 11–100 years old, and trees older than 100 years. We conducted genetic analyses of 26 allozyme loci using dormant buds from 405 individuals and 100 embryos. The results showed that the naturally regenerating Norway spruce population is genetically heterogeneous across the studied age classes. As determined by Chi squared tests, there were statistically significant differences in frequencies of alleles and genotypes as well as Wright’s index values (F) among the five age classes. The level of genetic differentiation (pairwise F_ST = 0.5–2.3 %) among the age class groups was equal to levels previously determined for various populations of this species. The Ewens-Watterson test for neutrality showed that one or two loci across different age classes of Norway spruce were affected by the selection process. The distinctiveness of embryo and seedling classes was confirmed by the number of detected alleles, the number of private alleles, the level of observed heterozygosity, and Wright’s index value. The results obtained in the present study indicate there are interesting dynamics of adaptation processes occurring in the natural age-diverse population of Norway spruce in the Bia?owie?a Primeval Forest.     

Positive effect of forest structural diversity on aboveground stand carbon stocks for even-aged Scots pine (Pinus sylvestris L.) stands in the Sarıçiçek Forest,Northern Turkey

This study examines the relationships between forest structural diversity indices and aboveground stand carbon storage for even-aged and pure Scots pine stands located in the Sar?çiçek Forest, Northern Turkey. In the even-aged Scots pine stands, 293 sample plots were selected to represent various stand conditions such as site quality, age, and stand density. The stand structural diversity, including Shannon’s, improved Shannon, Simpson’s, McIntosh, Margalef, and Berger–Parker indices, was used to correlate the stand carbon storage values. Positive partial correlation coefficients between stand carbon storage and forest structural diversity indices, including the improved Shannon index (r?=?0.770), Shannon’s index (r?=?0.742), Simpson’s index (r?=?0.703), the Berger–Parker index (r?=?0.657), the Gini index (r?=?0.390), and the Margalef index (r?=?0.327), were found at the 0.01 level. These results offer an enhancement of theories concerning positive relationships between stand carbon storage and stand structural diversity for pure and single-species forests. Moreover, regarding biodiversity suitability and stand carbon storage as carbon sinks, the results illustrate that forest stands with higher structural diversity may be preferred when used to mitigate global warming.     

Intra-annual growth response of adult Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis> [L.] KARST.) and European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.) to an experimentally enhanced,free-air ozone regime

Several findings indicate an impact of ozone on stem diameter growth leaving the question unanswered, if and how the intra-annual growth pattern is changed. In this study the hypotheses are tested, that (1) ozone will alter the absolute growth and (2) alter and shift the period of growth activity within a year. Our data originates from the free air ozone fumigation experiment ‘Kranzberger Forst’ in a mixed stand of Norway spruce and common beech near Freising/Germany. Annual and intra-annual growth reactions of a sample of five adult beech and five spruce trees, exposed to double ambient ozone were examined and compared to the same number of untreated reference trees. Diameter increments were measured with plastic diameter girth bands and high-resolution, automatically logging micro-dendrometers, mounted at breast height (1.3 m). We used the increment data from the growth periods 2000 to 2005. The high-resolution micro-dendrometer data were examined by fitting a Weibull function to the standardized annual growth profiles to obtain curve parameters for statistical tests. We estimated the parameters ‘T’ which represents the point of time, when 63% of the annual diameter increment is performed and the parameter ‘m’, the Weibull module, which was used as an indicator for the span of time needed to complete the annual growth. The statistical significance of these curve parameters, together with the absolute diameter increment, was tested by use of mixed regression models. The analysis of the growth curve parameters revealed a significantly altered intra-annual growth pattern of both species induced by ozone. Spruce under ozone showed reduced absolute annual diameter increment and a preponed growth activity compared to untreated trees. Beech’s absolute diameter increment was not affected under ozone, but its growth activity was delayed. For both species, ozone fumigation did not alter the individual length of the annual growing season. These results are discussed with respect to drought, tree ring anatomy and tree allometry. The study shows that ozone is able to change growth behaviour of trees even if increment losses are not obvious. This article belongs to the special issue "Growth and defence of Norway spruce and European beech in pure and mixed stands".     

Factors controlling soil water-recharge in a mixed European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.)–Norway spruce [<Emphasis Type="Italic">Picea abies</Emphasis> (L.) Karst.] stand

The spatial dynamics of soil water-recharge in a forest stand is the product of a number of interacting processes. This study focuses on the role of tree species and antecedent soil water content upon horizontal and vertical patterns of soil water recharge in heavy clay soils of a mixed European beech–Norway spruce stand and of a pure Norway spruce stand after rewetting periods with different rain quantities and intensities. Volumetric water content (VWC) was measured at 194 locations across 0.5-ha plots in each stand using time-domain reflectometry (TDR) with fixed 30- and 60-cm vertical waveguides. This was repeated 28 times (as close as possible) before and after rewetting periods during the vegetation seasons in 2000 and 2001. In addition, the locations of all trees within the plots were recorded. Geostatistics was used to describe the spatial correlation between VWC measurements and to interpolate soil water recharge in space. Spatial patterns of soil water recharge were then evaluated according to antecedent soil water-content and tree species distribution. Open-field precipitation of 30 mm (maximum intensity 10 mm h^–1) on extremely dry initial soil conditions resulted in higher subsoil (30–60 cm soil depth) recharge and erratic recharge patterns. This was presumably due to preferential flow in opening shrinkage cracks of the heavy clay soil. A comparable quantity and intensity of rainfall under moderately dry antecedent soil water conditions resulted in almost exclusively topsoil (0–30 cm soil depth) water recharge and patterns of recharge that were clearly related to tree species distribution. The higher recharge around beech trees can be attributed to the lower interception rates there. Spatial patterns of soil water recharge reflect patterns of antecedent soil water conditions.     

Is leaf area of Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis> L. Karst.) and European larch (<Emphasis Type="Italic">Larix decidua</Emphasis> Mill.) affected by mixture proportion and stand density?

Key message

Trees with otherwise equal dimensions have different leaf areas if they are located in different stand types. While leaf area of European larch is affected by mixture proportion, leaf area of Norway spruce is affected by stand density.

Context

Leaf area is a key parameter for evaluating growth efficiency of trees, and therefore needs to be measured as consistently and accurately as possible. This is even more important when comparing monospecific and mixed stands.

Aims

The aim of the study is to find combinations of parameters and allometric relationships that can be used to estimate accurately the leaf area of individual trees.

Methods

Allometries of the measured leaf area of 194 trees in 12 stands were analysed in order to find variables affecting leaf area. Existing functions from the literature were validated. Finally, models were fitted to find the most appropriate method for estimating leaf area of mixed and monospecific stands of Norway spruce and European larch.

Results

Allometric relationships of leaf area to other measurable characteristics of trees vary in different stand types. Besides individual tree dimensions such as diameter and crown surface area, leaf area of Norway spruce is related to stand density, whereas the leaf area of European larch is dependent on the admixture of Norway spruce in the stand.

Conclusion

In contrast to models for estimating individual tree leaf area of Norway spruce, models for leaf area of European larch have to consider mixture proportions in order to correctly interpret the growth efficiency of mixed stands.

     

The rise and fall of the black locust (Robinia pseudoacacia L.) in the “Siro Negri” Forest Reserve (Lombardy, Italy): lessons learned and future uncertainties

? The alluvial forests of the Ticino valley have been greatly reduced in size and are now represented by only a small number of fragmented remnants. To study the natural development of the black locust, an invasive species, on relatively undisturbed lowland forests, two permanent plots were established in 2005 in the “Siro Negri” Forest Reserve.

? The black locust became established almost exclusively between 1940 and 1960. The observed dynamic of the black locust in the Reserve was very similar to what has been observed in its native North American range: following the initial colonization, the black locust firmly established itself in the dominant and intermediate layers but did not regenerate. In addition to the absence of a significant younger population, the decline of the black locust is evident in an elevated mortality rate and higher proportion of black locust biomass in the total coarse woody debris (CWD)

? Our results support the hypothesis that the best strategy to control the spread of black locust is to avoid disturbances that favour black locust colonization, and to wait for natural suppression of the species by other trees. Due to the lack of past reference conditions and the future uncertainties, ongoing monitoring will be needed to fully understand the dynamics of forest ecosystem change in the Reserve.

     

Studies on the biology of <Emphasis Type="Italic">Cryphalus piceae</Emphasis> (Ratz.) (Coleoptera,Scolytidae) in the Bartin and Karabük regions of Turkey

The purpose of this study is to investigate the biology of Cryphalus piceae (Ratz.) (Col., Scolytidae) living in Abies bornmülleriana (Mattf.) in fir forests in the Western Black Sea region in Turkey. The dates of swarming, tree attack, egg-laying, and different stages of development are given. The species had two generations per year.     

Coarse root biomass and architecture of hybrid aspen ‘Crandon’ (Populus alba L. × P. grandidenta Michx.) grown in an agroforestry system in central Iowa,USA

In this study, we evaluated ‘Crandon’ coarse root biomass and architecture grown at different topographic positions and fertilizer rates. Complete excavations were conducted on a subset of trees after the first growing season and showed that root biomass was strongly related to stem biomass (R² = 0.93), but not topographic position or fertilizer rate. After the third growing season, subsamples of roots were collected from another subset of trees and showed coarse root architecture variables to be strongly related to several metrics of the tree and root size (R² = 0.61 to 0.82), while also differing by topographic position. Equations relating root biomass to stem biomass were derived from both methodologies (complete excavation v. subsampling for architecture measurements), and comparison of the equations indicated no difference in slopes (p = 0.59) or intercepts (p = 0.90), although the subsampling approach had a weaker model fit. Our results suggest ‘Crandon’ roots (i) adhere to strong allometric relationships with stem biomass, (ii) alter their architecture within the constraints of this allometric relationship according to site conditions, and (iii) can be subsampled to estimate root biomass from root architecture parameters with similar accuracy (but less precision) compared to complete excavations.     

Changes of soil chemistry,stand nutrition,and stand growth at two Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) sites in Central Europe during 40 years after fertilization,liming, and lupine introduction

Long-term (40 years) effects of two soil amelioration techniques [NPKMgCa fertilization + liming; combination of PKMgCa fertilization, liming, tillage, and introduction of lupine (Lupinus polyphyllus L.)] on chemical topsoil properties, stand nutrition, and stand growth at two sites in Germany (Pfaffenwinkel, Pustert) with mature Scots pine (Pinus sylvestris L.) forest were investigated. Both sites are characterized by base-poor parent material, historic N and P depletion by intense litter-raking, and recent high atmospheric N input. Such sites contribute significantly to the forested area in Central Europe. Amelioration resulted in a long-term increase of pH, base saturation, and exchangeable Ca and Mg stocks in the topsoil. Moreover, significant losses of the forest floor in organic carbon (OC) and nitrogen stocks, and a decrease of the C/N ratio in the topsoil were noticed. The concentrations and stocks of OC and N in the mineral topsoil increased; however, the increases compensated only the N, but not the OC losses of the forest floor. During the recent 40 years, the N nutrition of the stands at the control plots improved considerably, whereas the foliar P, K, and Ca concentrations decreased. The 100-fascicle weights and foliar concentrations of N, P, Mg, and Ca were increased after both amelioration procedures throughout the entire 40-year period of investigation. For both stands, considerable growth acceleration during the recent 40 years was noticed on the control plots; the amelioration resulted in an additional significant long-term growth enhancement, with the NPKMgCa fertilization liming + being more effective than the combination of PKMgCa fertilization, liming, tillage, and introduction of lupine. The comprehensive evaluation of soil, foliage, and growth data revealed a key relevance of the N and P nutrition of the stands for their growth, and a change from initial N limitation to a limitation of other growth factors (P, Mg, Ca, and water).