Needles In Summer Research Articles

Circulation of 137Cs in Various Forest Plants in the Chornobyl Exclusion Zone during the Year

This study investigated the content of 137Cs (a long-lived radioactive isotope of caesium) in various parts of Pinus sylvestris L. (Scotch pine) and Dicranum polysetum Sw. (rugose fork-moss) at three different sites within the exclusion zone of the Chornobyl nuclear power plant over two years. The Leliv site is located within the 10 km zone, while the Paryshiv and Dytiatky sampling sites are within the 30 km zone. Samples of different P. sylvestris organs were collected, including 1- and 2-year-old branches and needles and wood and outer bark, and the entire D. polysetum. Sampling was conducted every two weeks throughout the year during 2014 and 2015. The specific activity levels of 137Cs in the samples were measured using gamma spectrometry with a CANBERRA gamma spectrometer unit and a coaxial high-purity HPGe semiconductor detector. The study found that at the Leliv and Paryshiv sites, the highest content of 137Cs in living organs of P. sylvestris was found in the wood. At the Dytiatky site, the needles and branches of the first and second years had anomalously high concentrations of radiocaesium (137Cs). This could be due to a thin layer of forest litter (1.5 cm) at that site. The study also found significant changes in the specific activity levels of 137Cs in living pine organs throughout the year. The highest concentration was observed in pine branches and needles in summer, and the maximum values in wood were observed in winter. The study suggests that a constant circulation of 137Cs in the soil–plant system can cause seasonal changes in the content of 137Cs in living pine organs. Symbiotic mycorrhizal fungi can play an important role in the circulation of radiocaesium in forest ecosystems. The outer bark of P. sylvestris did not show any seasonal changes in the content of 137Cs. It may not be involved in radiocaesium redistribution inside the plant but can serve as a long-term source of this radionuclide entering the forest litter. The study found no seasonal changes in the accumulation of 137Cs by D. polysetum, which might be due to the physiological characteristics of this plant species. Based on the analysis of the conducted studies, the recommendation is to consider the seasonal changes in the content of 137Cs during monitoring activities and when using Scots pine in areas potentially contaminated with this radionuclide.

Углеводороды и сложные эфиры экстрактивных веществ хвои лиственницы сибирской

Siberian larch (Larix sibirica L.) is the main commercial species in Russia. Currently, larch woody greens are underutilized. They are considered a waste product from logging. This is due to the lack of knowledge on the composition of compounds and the variability of the raw material source itself as a result of the fall of the needles. The research purpose is to study the composition of hydrocarbons and esters from Siberian larch needles in summer and autumn collection from the Tomsk region. The shredded needles were extracted with propan-2-ol; then, after distillation of the solvent, substances soluble in petroleum ether (PE, 40–70 °С) were isolated. The latter were divided into free acids (31.5 % for green needles and 28.0 % for yellow needles) and neutral substances (59.8 and 48.1 %, respectively). Then, eutral substances were chromatographed on silica gel: hydrocarbons (2.43 and 3.02 %, hereinafter from neutral substances of green and yellow needles, respectively), esters (31.30 and 33.80 %) and triglycerides (11.70 % and 6.44 %). The ester and triglyceride fractions were exposed to alkaline hydrolysis and the acidic components of esters (9.12 and 24.80 %) and triacylglycerols (17.43 and 26.15 %) were produced. Fractions of unsaponifiable compounds, in addition to alcohols, contained unsaponifiables with unchanged Rf values on thin-layer chromatography (TLC). Fractions of unsaponifiables were chromatographed on silica gel, and then the isolated fractions were additionally chromatographed on silica gel with silver nitrate. The isolated compounds were identified by nuclear magnetic resonance (NMR) spectroscopy. In the acidic component of esters, the main components are linoleic and linolenic acids. Hydrocarbons are represented by sesquiterpenes in both collections of needles. A new aromatic hydrocarbon for coniferous plants, geranyl-p-cymene, has been identified. For the first time, polyprenols were isolated from Siberian larch greens, the structure of which differs from spruce and pine polyprenols by chain length according to NMR spectroscopy and mass spectrometry data. They contain from 14 to 20 isoprene links in the chain of molecules with predominance of prenol-17. The yield of polyprenols was 12.8–14.9 % of neutral substances of yellow and green needles, respectively. Tetracyclic triterpene alcohols and sterols were isolated from green needles. Triterpene alcohols were not found in yellow needles. For citation: Mikson D.S., Roshchin V.I. Hydrocarbons and Ethers of Extractive Substances of Siberian Larch Needles. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 3, pp. 170–185. DOI: 10.37482/0536-1036-2021-3-170-185

Foliar P nutrition of European beech (Fagus sylvatica L.) depends on the season but remains unaffected by co-cultivation with silver fir (Abies alba Mill.)

Beech (Fagus sylvatica) and silver fir (Abies alba) are often cultivated in mixed stands and, hence, compete for water and nutrients. Besides nitrogen (N), also phosphorus (P) is an important nutrient for growth and development. Beech trees in Central Europe grow on both P-poor and P-rich soils, thereby showing similar growth and low variation in foliar P. The central aim of the present study was to test the hypothesis that variations in foliar P contents of beech are driven by seasonal changes rather than by the competition with silver fir. It was further hypothesized that P contents in silver fir needles depend on needle age and forest site. To test these hypotheses, P contents and P fractions, i.e. organic-bound P (Porg) and inorganic phosphate P (Pi), were measured in the foliage of beech trees from pure beech and mixed beech/silver fir plots as well as in needles of silver fir of the mixed plots. The forest sites investigated are located in Central Europe in the Black Forest, Germany, and in Croatia near the south-eastern distribution limit of beech and are all poor in plant-available soil P. The analyses showed that the main driver of P contents and P fractions in beech leaves at all forest sites is the season and that competition with silver fir had no effect. Hence, the present results demonstrate the high plasticity of beech trees to adapt to both poor plant-available soil P and competition with silver fir. Total P contents of silver fir needles were higher at the Croatian site compared to the Black Forest sites and originated from higher foliar Pi contents. One third of the P present in current-year needles in late summer was remobilized and exported until the needles reached the age of 1 year. The difference in P contents between current-year and 1-year-old needles can be seen as the amount of P resorbed from 1-year-old needles in summer during the generation of new needles to support the P demand of current-year needles for growth and development.

Effects of the needle bladder rust (Chrysomyxa rhododendri) on Norway spruce: implications for subalpine forests

Norway spruce trees in the subalpine forests of the European Alps are frequently attacked by the needle rust Chrysomyxa rhododendri. The obligate parasite undergoes a complex life cycle with a host shift between rhododendrons (Rhododendron sp.) and Norway spruce [Picea abies (L.) Karsten] and causes a yellowing and defoliation of the current-year needles in summer. Infected trees show several anatomical, morphological and physiological modifications, including a decrease in pigment content and net photosynthesis of infected needles, lower biomass production and reduced radial and height growth. The consequences are diminished timber yield and cripple growth. Because of repeated heavy infections in recent years, forest managers report increasing difficulties in both natural regeneration and afforestation at high elevation sites, where rhododendrons occur. This review gives a summary of the present knowledge about the effects of C. rhododendri infections on Norway spruce, including so far unpublished findings and with particular attention to the phenomena of resistant trees. Implications for subalpine forests and counter strategies are discussed.

Comprehensive assessment of pine needles as bioindicators of PAHs using multivariate analysis. The importance of temporal trends

The importance of the annual and seasonal trends associated to the polycyclic aromatic hydrocarbons (PAHs) biomonitoring by pine needles are studied with a comprehensive use of univariate and multivariate analysis tools. For this purpose, four pine needle sampling campaigns (winter, spring, summer and autumn 2007) were carried out in 29 sites from Portugal. Needles from Pinus pinaster Ait. and Pinus pinea L. trees were collected from all year-classes available in each tree, corresponding to the different shoots of needles coming out every spring and the results of both species were treated separately. Annual trends of polycyclic aromatic hydrocarbons (PAHs) contamination indicate a general increase from the least to the most exposed year-classes, for all seasons. The mean values for the sum of 16 PAHs ranged from 71 ± 33 ng g −1 (dry weight – dw) for new year (2007) needles in the summer to 514 ± 317 ng g −1 (dw) for 2-year needles (2005) in the spring for P. pinea, and between 90 ± 50 ng g −1 (dw) for new year (2007) needles in the summer and 1212 ± 436 ng g −1 (dw) for 3-year needles (2004) in summer for P. pinaster. The seasonal evolution shows the highest concentrations in the winter, then declining to the lowest levels in the summer and rising again from summer to autumn. Principal component analysis confirmed differences between seasons and needle year-classes, more visible for P. pinea samples. The cooler seasons have more affinity towards the lighter more abundant PAHs, as do the older needles. Differences between both pine species are also evident.

Needle age-related and seasonal photosynthetic capacity variation is negligible for modelling yearly gas exchange of a sparse temperate Scots pine forest

Abstract. In this study, we quantified the predictive accuracy loss involved with omitting photosynthetic capacity variation for a Scots pine (Pinus sylvestris L.) stand in Flanders, Belgium. Over the course of one phenological year, we measured the maximum carboxylation capacity at 25 °C (Vm25), the maximum electron transport capacity at 25 °C (Jm25), and the leaf area index (LAI) of different-aged needle cohorts in the upper and lower canopy. We used these measurements as input for a process-based multi-layer canopy model with the objective to quantify the difference in yearly gross ecosystem productivity (GEP) and canopy transpiration (Ecan) simulated under scenarios in which the observed needle age-related and/or seasonal variation of Vm25 and Jm25 was omitted. We compared simulated GEP with estimations obtained from eddy covariance measurements. Additionally, we measured summer needle N content to investigate the relationship between photosynthetic capacity parameters and needle N content along different needle ages. Results show that Vm25 and Jm25 were, respectively, 27% and 13% higher in current-year than in one-year old needles. A significant seasonality effect was found on Vm25, but not on Jm25. Summer needle N content was considerably lower in current-year than in one-year-old needles. As a result, the correlations between Vm25 and needle N content and Jm25 and needle N content were negative and non-significant, respectively. Some explanations for these unexpected correlations were brought forward. Yearly GEP was overestimated by the canopy model by ±15% under all scenarios. The inclusion and omission of the observed needle age-related Vm25 and Jm25 variation in the model simulations led to statistically significant but ecologically irrelevant differences in simulated yearly GEP and Ecan. Omitting seasonal variation did not yield significant simulation differences. Our results indicate that intensive photosynthetic capacity measurements over the full growing season and separate simulation of needle age classes were no prerequisites for accurate simulations of yearly canopy gas exchange. This is true, at least, for the studied stand, which has a very sparse canopy and is exposed to high N deposition and, hence, is not fully representative for temperate Scots pine stands. Nevertheless, we believe well-parameterized process-based canopy models – as applied in this study – are a useful tool to quantify losses of predictive accuracy involved with canopy simplification in modelling.

A Comparison of Needle Retention on Japanese Black Pine and Japanese Red Pine

Needle retention (number of needle sets), needle density, height increment and radial increment were surveyed on seven Japanese black pines (Pinus thunbergii Parl.) and seven Japanese red pines (Pinus densiflora Sieb. et Zucc.) growing on the same site. Number of needle sets on branches with respect to whorl position was estimated visually. In 1999, maximum summer needle retention was observed on the fifth and sixth whorl from the top, with values of 3.4 needle sets for the black pines and 2.4 needle sets for the red pines, respectively. The needle trace method (NTM) was used to determine needle retention and needle density along the main stems retrospectively for the years 1968–1998. The long-term mean summer needle retention along the main stem was 3.7 needle sets for the black pines and 2.2 needle sets for the red pines. In both pine species, the number of needle sets varied from year to year. However, the long-term budget between newly born and annually shed needle sets was in equilibrium. The long-term average of needle density per cm of stem shoot was 9.4 needle pairs for the black pines and 7.4 needle pairs for the red pines. The results showed clear intra-specific and inter-specific similarities in needle retention, height increment and radial increment trends. The values for number of needle sets, height increment and radial increment positively increased with favorable growing conditions, whereas the value of needle density had an opposite tendency.

Needle chronologies on Pinus sylvestris in northern Estonia and southern Finland

A needle trace method was used to reveal the chronology of needle retention on Scots pine (Pinus sylvestris L.) in southern Finland (two stands) and northern Estonia (two stands). The average annual summer needle retention along the main stem varied from 2.2 to 3.1 in Estonian stands and between 3.4 and 4.2 in Finnish stands during the period 1966–1990. The 23-year-mean needle age was 3.0 and 2.1 years in Finland and Estonia, respectively. In all stands, the mean needle age decreased sharply in 1980s.

New hosts for Choanatiara lunata

Choanatiara lunata is a coelomycetous fungus producing conidia with funnel-shaped appendages. The species was originally reported on fallen needles of Pinus resinosa and P. strobus in Ontario, Canada. Our systematic work on coelomycetes in Pinus spp. was carried out on 29 different pine hosts (species, varieties, forms or cultivars) at the arboretum of the Montreal Botanical Garden. Choanatiara lunata was isolated (on PDA, MA, CMA) from 9 (31%) of the pine hosts investigated. From those, four hosts are species indigenous to North America: P. albicaulis (subgenus Haploxylon), P. resinosa, P. ponderosa, and P. jeffreyi (subgenus Diploxylon). The other five hosts are pines exotic to North America. Three are indigenous to Europe: P. nigra ‘Laricio’, P. nigra ‘Nigra’, and P. nigra ‘Pallasiana’ (subgenus Diploxylon), and two are indigenous to East Asia: P. densiflora and P. tabulaeformis (subgenus Diploxylon). Except for P. resinosa, these are all new hosts for this fungus. The fungus was associated with symptoms of summer needle necrosis in the crown. For the first time, the cultural characteristics of the fungus are given, and the morphology of C. lunata described in this work was compared to the one reported by Nag Raj (1993).

Nitrogen allocation and carbon isotope fractionation in relation to intercepted radiation and position in a young Pinus radiata D. Don tree

The three dimensional distribution of intercepted radiation, intercellular CO2 concentration (Ci) and late summer needle nitrogen (N) concentration were determined at the tips of all 54 branches in a 6·2‐m‐tall Pinus radiata D. Don tree growing in a New Zealand plantation. Measurements included above‐ and below‐canopy irradiance, leaf stable carbon isotopic composition (δ13C) and tree canopy architecture. The radiation absorption component of the model, MAESTRO, was tested on site and then used to determine the branch tip distribution of intercepted radiation. We hypothesized that in branch tip needles: (i) the allocation of nitrogen and other nutrients would be closely associated with the distribution of intercepted radiation, reflecting carbon gain optimization theory, and (ii) Ci would predominantly reflect changes in photosynthetic rate (A) rather than stomatal conductance (gs), indicating that the increase in A for a given increase in N concentration was larger than the corresponding increase in gs. Needle nitrogen concentration was poorly related to intercepted radiation, regardless of the period over which the latter was calculated. At a given height, there was a large azimuthal variation in intercepted radiation but N concentration was remarkably uniform around the tree canopy. There was, however, a linear and positive correspondence between N concentration and δ13C and needle height above ground (r2 = 0·73 and 0·68, respectively). The very strong linear correspondence between N concentration and Ci (r2 = 0·71) was interpreted, using gas exchange measurements, as supporting our second hypothesis. Recognizing the strong apical control in P. radiata and possible effects of leaf nitrogen storage in an evergreen species, we propose that the tree leader must have constituted a very strong carbon sink throughout the growing season, and that the proximity of branch tip needles to the leader affected their photosynthetic capacity and nutrient concentration, independent of intercepted radiation. This implies an integrated internal determination of resource allocation within the tree and challenges the current convention that resources are optimally distributed according to the profile of intercepted radiation.

Mycofloral succession on Pinus densiflora needles on a moder site

Mycofloral succession on decaying pine needles in aPinus densiflora forest on a moder site was investigated in Sugadaira, Nagano Pref., central Japan. Dead needles on the tree, fallen needles obtained from two recognizable sublayers of the L layer and the upper sub-layer of the F1 layer in the organic horizon were examined for their fungal flora using both washing and surface sterilization techniques. The major interior colonizer in freshly fallen needles varied with the season:Chaetopsina fulva in summer andSelenosporella curvispora in the other seasons.Thysanophora penicillioides was a remarkable external colonizer of freshly fallen needles in summer, while soil fungi were external colonizers of such needles in the other seasons. A possible successional change of major fungi with the needle decay was suggested. The observed seasonal alternation of the species colonizing freshly fallen needles was discussed in relation to climatic conditions.

Development of needle retention in Scots pine (Pinus sylvestris) in 1957?1991 in northern and southern Finland

The needle trace method was used to study retrospectively the long-term latitudinal variation in needle retention in Scots pine (Pinus sylvestris L.) in Finland. The mean annual summer needle retention (ANR) along the main stem varied from 3.4 to 6.0 needle sets during the period 1957–1991. The lowest values were observed in southern and the highest in northern Finland. The length of the growing season, expressed as the thermal sum (threshold value +5 °C), was negatively correlated with the mean ANR (r=-0.96). The geographical needle retention pattern (NRP) for the period 1957–1991 showed a clearly increasing trend from 1957 to 1969 (southern Finland) and to 1975 (northern Finland); thereafter, the NRP tended to decrease close to its minimum value recorded in 1991. The general level of the NRP was approximately 5.0 needle sets in northern Finland and 3.5–4.0 needle sets in southern Finland. The NRP, with its 6–12 year cycle for southern Finland, was clearly periodical. Differences in the NRP among the ten stands in southern Finland were small, whereas the said periodicity was missing and the differences were high among the stands in northern Finland. The results indicate that variation in the number of needle sets, viz. defoliation of pines, is a normal phenomenon. The role of net carbon assimilation as a regulator of the number of needle sets is discussed.

The effect of needle age on the acceptability of Sitka spruce needles to the aphid, Elatobium abietinum (Walker).

A comparison of the feeding behaviour of E. abietinum on current year needles and previous year needles of P. sitchensis revealed that during the summer months the aphids preferentially settled on previous year needles, this response not being evident in winter. Aphids on current year needles in summer took a much longer period of time to commence sap uptake than in winter, intake ceasing following a very short feeding period. On previous year needles sap uptake in December commenced after a shorter feeding period than in June. Analysis of total and soluble nitrogen levels in Sitka spruce needles showed that current year needles had initially higher levels during shoot elongation in May and early June, but that previous year needles had higher levels for most of the remainder of the year. Quantitative analyses of amino acids revealed that in current year needles the levels were generally lower than in previous year needles. Less marked proportional differences were observed between previous year needles in May and in July/August when the needles were unsuitable. Addition of amino acids in solution into cut current year shoots resulted in increased longevity on shoots containing introduced iso-leucine, histidine and methionine and revealed a general imbalance of the amino acids.