Conifer Needles Research Articles

Loss of soil carbon and nitrogen indicates climate change-induced alterations in a temperate forest ecosystem

Climate warming is expected to influence terrestrial biogeochemical cycles by modifying the quality and quantity of plant litter input to soils. Although a growing number of studies recognize the importance of plant litter input in influencing the loss of soil organic matter (SOM) through a phenomenon called the priming effect (PE), the exact mechanisms behind PE are not well known. Importantly, most PE research is based on short term pot experiments in which fresh organic matter (FOM) input is represented by a single addition of compounds of unnaturally simple chemical composition. Furthermore, only a few studies exist in which the PE was explored in terms of organic C (SOC) and total N content in the soil. Here, we report results of a 3-year long litter manipulation study conducted under natural conditions in a broadleaved Korean pine forest in N-E China. We show that the extra supply (twice the normal input) of aboveground tree litter composing of conifer needles, leaves and small twigs was associated not only with slightly decreased SOC (by 5%) but especially that of soil total N (STN) (by 15%) content in the top soil (0–5 cm depth). In contrast, removal of litter resulted in an increased (ca. 15%) amount of both SOC and STN during the study when compared to control soils receiving natural litter input. Despite the enhanced leaf litter decomposition rate in the treatment receiving extra litter, the changes in SOC and STN were related neither to soil microbial biomass nor to community composition. The amount of N lost (40.0 g m−2) in the soil due to litter addition was ca. three times the amount of N added (12.3 g m−2) via the litter, while the amount of C lost (238 g m−2) was about one third of that added (940 g m−2), suggesting that soil N in our research site is more prone to the PE than soil C. As we did not manipulate belowground FOM input, our results suggest that input of aboveground litter rather than that by roots explained the PE in our study. Results of our long-term study conducted under natural conditions in undisturbed forest soils highlight the large potential of recalcitrant, aboveground litter to affect the PE, which should not go unnoticed when predicting the role of forest soils under conditions (such as climate warming) when these soils act as C sinks.

Bidirectional reflectance factor measurement of conifer needles with microscopic spectroscopy imaging

Leaf reflectance is widely used to retrieve leaf chlorophyll content (Cab) and parameterize canopy radiative transfer models. Measurements of broadleaf reflectance are typically made by using integrating sphere devices, but the approach is generally limited in conifer needle measurements due to the narrow needle coverage relative to the sample port of the integrating sphere. In this study, we proposed a method to measure the bidirectional reflectance factor (BRF) of needles by integrating a hyperspectral imaging spectrometer and an optical microscope. Pure needle pixels can be easily extracted from hyperspectral images after microscope magnification. The method was first validated by the narrow strips of broad leaves as proxies of needles, resulting in the difference between the measured BRF of strips and the BRF of whole broad leaves in the visible bands (400–700 nm) and in the near-infrared bands (700–1000 nm) being 0.0043 and 0.019, respectively. The method was also indirectly verified by tracking the variation in the natural needle BRF with its Cab, resulting in the change in BRF being consistent with the change in Cab. In addition, linear relationships between the needle Cab and the classic vegetation indices (i.e., the red-edge simple ratio and normalized difference vegetation index) calculated from the BRF were found. Apart from the above, we found that (1) the BRF of the abaxial side has a discrepancy with that of the adaxial side of needles, (2) the BRF of a needle varies with its azimuth, hence affecting the correlation between vegetation indices and Cab, and (3) filtering the specular reflection on the microsurfaces of the needle could enhance the correlation between the vegetation indices and needle Cab. The method is expected to accurately measure the BRF of needles and hence to improve the applications of needle optical properties in plant sciences, ecology, and remote sensing fields.

Frozen mountain pine needles: The endodermis discriminates between the ice-containing central tissue and the ice-free fully functional mesophyll.

Conifer (Pinaceae) needles are the most frost-hardy leaves. During needle freezing, the exceptional leaf anatomy, where an endodermis separates the mesophyll from the vascular tissue, could have consequences for ice management and photosynthesis. The eco-physiological importance of needle freezing behaviour was evaluated based on the measured natural freezing strain at the alpine treeline. Ice localization and cellular responses to ice were investigated in mountain pine needles by cryo-microscopic techniques. Their consequences for photosynthetic activity were assessed by gas exchange measurements. The freezing response was related to the microchemistry of cell walls investigated by Raman microscopy. In frozen needles, ice was confined to the central vascular cylinder bordered by the endodermis. The endodermal cell walls were lignified. In the ice-free mesophyll, cells showed no freeze-dehydration and were found photosynthetically active. Mesophyll cells had lignified tangential cell walls, which adds rigidity. Ice barriers in mountain pine needles seem to be realised by a specific lignification patterning of cell walls. This, additionally, impedes freeze-dehydration of mesophyll cells and enables gas exchange of frozen needles. At the treeline, where freezing is a dominant environmental factor, the elaborate needle freezing pattern appears of ecological importance. This article is protected by copyright. All rights reserved.

Spatiotemporal patterns in differences between the 137Cs concentrations of forest and stream litters: effect of leaching.

Forest-stream ecotones possess prominent detritus-based food webs, and 137Cs-contaminated litter can influence the contamination levels of animals inhabiting such ecosystems. The effects of leaching on contaminated litter induce greater absolute differences between the 137Cs concentrations of forest and stream litter in more contaminated sites. Because 137Cs concentrations in litter can be attenuated temporally, spatiotemporal patterns in the differences in 137Cs concentrations between forest and stream litter may vary depending on both the amount of 137Cs deposition and the passage of time. To test this hypothesis, we sampled coniferous needle and broad-leaved deciduous litter in forests and streams at seven forested headwater sites affected by the Fukushima nuclear accident 3.24 and 11.24 years after the accident. We found that 137Cs concentrations in the two litter types were one order of magnitude lower 11.24 years after the accident than 3.24 years afterwards. The absolute difference in 137Cs activity concentrations of litter between forest and stream ecosystems was higher at more contaminated sites both 3.24 and 11.24 years after the accident. The spatiotemporal changes in litter contamination provide insight into 137Cs dynamics and complex transfer in the detritus-based food webs of forest-stream ecotones.

Antioxidant potential, mineral composition and inhibitory effects of conifer needle extract on hyaluronidase - prospects of application in functional food

Antioxidant potential, mineral composition and inhibitory effects of conifer needle extract on hyaluronidase - prospects of application in functional food

Differences in accumulation of polycyclic aromatic compounds (PACs) among eleven broadleaved and conifer tree species

PACs (polycylic aromatic compounds) are air pollutants formed in incomplete combustion, e.g., in vehicle engines. Vegetation can potentially remove substantial amounts and act as bioindicators of these pollutants. Increased knowledge of the pollutant removal efficiencies of different tree species is essential for understanding the potential benefits trees can provide urban residents. We investigated the leaf/needle content of the two PAC groups, polycyclic aromatic hydrocarbons (PAHs, 32 compounds) and dibenzothiophenes (DBTs, 6 compounds) in seven broadleaved and four conifer tree species in an arboretum of South-West Sweden. PAHs were grouped into low-molecular (L-PAHs, largely gaseous), medium-molecular (M-PAHs, both gaseous and particle-bound) and high-molecular mass (H-PAHs, largely particle-bound) PAHs. DBTs are organosulphur compounds with two benzene rings. In general, conifer needles were stronger accumulators of PACs than leaves of broadleaved trees. Comparing three-year-old and one-year-old needles showed that evergreen conifers accumulated L-PAHs, M-PAHs, H-PAHs and DBTs over several years. In deciduous trees, L-PAHs and DBTs declined from June to September, M-PAHs had no significant net change, but for H-PAHs, there was a significant net accumulation. Conifers had a similar or lower net average annual accumulation of H-PAHs than broadleaved trees, except the deciduous conifer Larix, which had the highest uptake rate of this toxicologically important PAH category. Our results suggest that L-PAH accumulation depends on leaf/needle mass or volume, while for H-PAHs leaf/needle area is more important. This explains why conifers represented a stronger sink for L-PAHs and M-PAHs. DBT accumulation in leaves/needles was similar to that of L-PAHs. An important conclusion is that tree leaves/needles accumulate substantial amounts of PAC with strong and complex contrasts between tree species and PAC groups. Another implication of our data is that conifer needles are useful as bioindicators for PAC pollution since they accumulate all PAC categories over several years.

Accuracy of Defoliation Estimates from Aerial and Ground Surveys in a Boreal Forest during an Outbreak of the Hemlock Looper, Lambdina fiscellaria (Guenée)

Annual estimates of defoliation are important tools for managing forest insect defoliators such as the hemlock looper, which feeds on conifer needles of all age classes. We tested the accuracy of defoliation classes obtained from aerial surveys by comparing them with ground-based estimates during a recent outbreak of this insect. We used an approach derived from the Fettes method to estimate defoliation on the current-year shoots as well as on the shoots of the four previous years. Defoliation on the current-year shoots provided accurate estimates of the overall defoliation and the strength of the relationship gradually decreasing for one-year-old to four-year-old foliage. The aerial survey provided accurate estimates of light and moderate defoliation during the first year of the outbreak, but accuracy was lower for both ends of the defoliation gradient and was much less reliable after the second year of the outbreak. All levels of defoliation were then observed in stands where defoliation had not been detected by an aerial survey. Cumulative defoliation on all age classes of foliage brings a new challenge to crews assigned to aerial survey programs. Ground-level defoliation estimates on the current-year shoots can help appraise the risk of tree mortality in the following year.

Conifer Needle Phyllosphere as a Potential Passive Monitor of Bioaerosolised Antibiotic Resistance Genes.

Monitoring antibiotic resistance genes (ARGs) is vital to the One Health approach to tackling the antibiotic resistance crisis. It has been suggested that conifer needles can be used as passive bioaerosol samplers. Here, the use of conifer needles as biomonitors of ARGs in bioaerosols was assessed as a proof-of-concept. Needles were collected from trees surrounding pig farms, villages, and forest sites in Québec, Canada. Needles were homogenised and DNA was extracted. Results of qPCR analyses showed biomass estimates were consistent across samples. Number and quantity of ARGs was significantly lower in forest sites when compared to the farm and village, comprising a distinct resistome. Consistent with previous findings, the most common ARGs were tetracyclines and sulfonamides, which were found close to agricultural activities. Although results were limited, there is great potential for using the conifer phyllosphere as a passive bioaerosol sampler. This method represents an accessible way to promote ARG surveillance over long distances from point sources.

Transitions of foliar mycobiota community and transcriptome in response to pathogenic conifer needle interactions

Profiling the host–mycobiota interactions in healthy vs. diseased forest ecosystems helps understand the dynamics of understudied yet increasingly important threats to forest health that are emerging due to climate change. We analyzed the structural and functional changes of the mycobiota and the responses of Pinus contorta in the Lophodermella needle cast pathosystem through metabarcoding and metatranscriptomics. When needles transitioned from asymptomatic to symptomatic, dysbiosis of the mycobiota occurred, but with an enrichment of Lophodermella pathogens. Many pathogenicity-related genes were highly expressed by the mycobiota at the necrotrophic phase, showing an active pathogen response that are absent in asymptomatic needles. This study also revealed that Lophodermella spp. are members of a healthy needle mycobiota that have latent lifestyles suggesting that other pine needle pathogens may have similar biology. Interestingly, Pinus contorta upregulated defense genes in healthy needles, indicating response to fungal recognition, while a variety of biotic and abiotic stresses genes were activated in diseased needles. Further investigation to elucidate the possible antagonistic interplay of other biotic members leading to disease progression and/or suppression is warranted. This study provides insights into microbial interactions in non-model pathosystems and contributes to the development of new forest management strategies against emerging latent pathogens.

Physiological and climate controls on foliar mercury uptake by European tree species

Abstract. Despite the importance of vegetation uptake of atmospheric gaseous elemental mercury (Hg(0)) within the global Hg cycle, little knowledge exists on the physiological, climatic, and geographic factors controlling stomatal uptake of atmospheric Hg(0) by tree foliage. We investigate controls on foliar stomatal Hg(0) uptake by combining Hg measurements of 3569 foliage samples across Europe with data on tree species' traits and environmental conditions. To account for foliar Hg accumulation over time, we normalized foliar Hg concentration over the foliar life period from the simulated start of the growing season to sample harvest. The most relevant parameter impacting daily foliar stomatal Hg uptake was tree functional group (deciduous versus coniferous trees). On average, we measured 3.2 times higher daily foliar stomatal Hg uptake rates in deciduous leaves than in coniferous needles of the same age. Across tree species, for foliage of beech and fir, and at two out of three forest plots with more than 20 samples, we found a significant (p<0.001) increase in foliar Hg values with respective leaf nitrogen concentrations. We therefore suggest that foliar stomatal Hg uptake is controlled by tree functional traits with uptake rates increasing from low to high nutrient content representing low to high physiological activity. For pine and spruce needles, we detected a significant linear decrease in daily foliar stomatal Hg uptake with the proportion of time during which water vapor pressure deficit (VPD) exceeded the species-specific threshold values of 1.2 and 3 kPa, respectively. The proportion of time within the growing season during which surface soil water content (ERA5-Land) in the region of forest plots was low correlated negatively with foliar Hg uptake rates of beech and pine. These findings suggest that stomatal uptake of atmospheric Hg(0) is inhibited under high VPD conditions and/or low soil water content due to the regulation of stomatal conductance to reduce water loss under dry conditions. Other parameters associated with forest sampling sites (latitude and altitude), sampled trees (average age and diameter at breast height), or regional satellite-observation-based transpiration product (Global Land Evaporation Amsterdam Model: GLEAM) did not significantly correlate with daily foliar Hg uptake rates. We conclude that tree physiological activity and stomatal response to VPD and soil water content should be implemented in a stomatal Hg model to assess future Hg cycling under different anthropogenic emission scenarios and global warming.

A modified, step-by-step procedure for the gentle bleaching of delicate fossil leaf cuticles

Cuticular analysis has long been used by palaeobotanists for the identification of fossil leaves, and a variety of chemical procedures has been developed to extract and prepare fossil cuticles. However, even commonly used solutions may be too harsh for the preparation of extremely delicate cuticles. Here we offer a step-by-step protocol for the preparation of fragile conifer cuticles using sodium hypochlorite, otherwise known as household bleach. Conifer needles from the Miocene lignites of the Adendorf and Hambach open-mine pits in western Germany were prepared using a mild solution of this oxidizing agent. The cuticles had proven to be too fragile for most maceration chemicals, including Schulze’s reagent, which even disintegrated the cuticles that were given a protective coating. However, it was discovered that trimming the leaf margins and damaged areas prior to a short exposure to 5–10% sodium hypochlorite solution resulted in the good preparation of the cuticle. Furthermore, this modified method allowed for the preparation of large areas of leaf. While this procedure may not be suitable for all cuticles, it is offered here as an easy and gentle method for preparing extremely delicate conifer cuticles that are destroyed by other chemicals and protocols.

Small geographical variability observed in Norway spruce needle spectra across Europe

Foliage spectra form an important input to physically-based forest reflectance models. However, little is known about geographical variability of coniferous needle spectra. In this research note, we present an assessment of the geographical variability of Norway spruce ( (L.) H. Karst.) needle albedo, reflectance, and transmittance spectra across three study sites covering latitudes of 49–62°N in Europe. All spectra were measured and processed using exactly the same methodology and parameters, which guarantees reliable conclusions about geographical variability. Small geographical variability in Norway spruce needle spectra was observed, when compared to variability observed between previous measurement campaigns (employing slightly varying measurement and processing parameters), or to variability between plant functional types (broadleaved vs. coniferous). Our results suggest that variability of needle spectra is not a major factor introducing geographical variability to forest reflectance. The results also highlight the importance of harmonizing measurement protocols when collecting needle spectral libraries. Furthermore, the data collected for this study can be useful in studies where accurate information on spectral differences between broadleaved and coniferous tree foliage is needed.Picea abies

Mercury accumulation in leaves of different plant types – the significance of tissue age and specific leaf area

Abstract. Mercury, Hg, is one of the most problematic metals from an environmental perspective. To assess the problems caused by Hg in the environment, it is crucial to understand the processes of Hg biogeochemistry, but the exchange of Hg between the atmosphere and vegetation is not sufficiently well characterized. We explored the mercury concentration, [Hg], in foliage from a diverse set of plant types, locations and sampling periods to study whether there is a continuous accumulation of Hg in leaves and needles over time. Measurements of [Hg] were made for deciduous and conifer trees in Gothenburg, Sweden (botanical garden and city area), as well as for evergreen trees in Rwanda. In addition, data for wheat from an ozone experiment conducted at Östad, Sweden, were included. Conifer data were quantitatively compared with literature data. In every case where older foliage was directly compared with younger, [Hg] was higher in older tissue. Covering the range from the current year up to 4-year-old needles in the literature data, there was no sign of Hg saturation in conifer needles with age. Thus, over timescales of approximately 1 month to several years, the Hg uptake in foliage from the atmosphere always dominated over Hg evasion. Rwandan broadleaved trees had generally older leaves due to lack of seasonal abscission and higher [Hg] than Swedish broadleaved trees. The significance of atmospheric Hg uptake in plants was shown in a wheat experiment where charcoal-filtrated air led to significantly lower leaf [Hg]. To search for general patterns, the accumulation rates of Hg in the diverse set of tree species in the Gothenburg area were related to the specific leaf area (SLA). Leaf-area-based [Hg] was negatively and non-linearly correlated with SLA, while mass-based [Hg] had a somewhat weaker positive relationship with SLA. An elaborated understanding of the relationship behind [Hg] and SLA may have the potential to support large-scale modelling of Hg uptake by vegetation and Hg circulation.

Does Mixing Tree Species Affect Water Storage Capacity of the Forest Floor? Laboratory Test of Pine-Oak and Fir-Beech Litter Layers

During the last decade, tree species mixing has been widely supported as a silvicultural approach to reduce drought stress. However, little is known on the influence of tree species mixing on physical properties and the water storage capacity of forest soils (including the forest floor). Thus, the study aimed to analyze the effect of mixing pine needles and oak leaves and mixing fir needles and beech leaves on hydro-physical properties of the litter layer during laboratory tests. We used fir-beech and pine-oak litter containing various shares of conifer needles (i.e., 0, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%) to determine the influence of the needle admixture on bulk density, total porosity, macroporosity, water storage capacity, the amount of water stored in pores between organic debris and the degree of saturation of mixed litter compared to broadleaf litter (oak or beech). We found that the admixture of fir needles increased the bulk density of litter from 7.9% with a 5% share of needles to 55.5% with a 50% share (compared to pure beech litter), while the share of pine needles < 40% caused a decrease in bulk density by an average of 3.0–11.0% (compared to pure oak litter). Pine needles decreased the water storage capacity of litter by about 13–14% with the share of needles up to 10% and on average by 28% with the 40 and 50% shares of pine needles in the litter layer. Both conifer admixtures reduced the amount of water stored in the pores between organic debris (pine needles more than fir needles).

Determination of the Volatile Organic Compounds (VOCs) in Mature and Immature Foliage of Five Species of Pinaceae by Gas Chromatography–Mass Spectrometry (GC-MS) with Principal Component Analysis (PCA) and Cluster Analysis (CA)

Conifer needles are rich in resources and have essential ecological and biological functions. However, comparative analysis of the volatile components of immature and mature needles of the family Pinaceae has not been reported to date. In this study, headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (GC-MS) was used to identify the volatile organic compounds (VOCs) in the immature and mature needles of five Pinaceae species. Altogether, 51 VOCs were identified, 31 of which reportedly show biological activity. The identified compounds include alcohols (6), terpenes (35), esters (7), and others (3). Terpenes were the major metabolites (78.38% to 97.18%) in the needles of the conifers. The needles were divided into four categories based on principal component analysis (PCA) and cluster analysis (CA). This is the first study to show a detailed examination of the differences in VOCs between immature and mature conifer needles. Furthermore, immature and mature needles of the five species were distinguished based on their specific VOCs. Our findings provide a reference for the utilization of conifer needles as valuable renewable resources.

Characteristics of airborne particles retained on conifer needles across China in winter and preliminary evaluation of the capacity of trees in haze mitigation

To fully understand the characteristics of particulate matter (PM) retained on plant leaves (PMR) and the effect of vegetation on haze on a large spatial scale, we investigated needle samples collected from 78 parks and campuses in 31 cities (30 provincial cities) of China and developed a comprehensive method to characterise PMR. Both the PMR load (including water-insoluble particulate matter (WIPM), water-soluble inorganic ions (WSIS) and water-soluble organic matter (WSOM)), with a mean value of 554 ± 345 mg m−2 leaf area, and component profiles of PMR showed obvious spatial variation across the cities. Though haze pollution levels vary greatly among the 31 cities, the PM retention capacity of needles does not depend on haze level because PMR generally reaches saturation before precipitation in winter. The water-soluble component (WSC, the sum of WSIS and WSOM) accounted for 52.3% of PMR on average, among which WSIS and WSOM contributed 21.4% and 30.9% to PMR, respectively. The dominant ions of WSIS in PMR in the cities were Ca2+, K+ and NO3−, indicating that raised dust, biomass combustion and traffic exhaust are significant sources of PM in China. Compared with previous reports, the particle size distributions of PMR and PM across China were consistent, with fine PM (PM2.5) constituting a substantial proportion (43.8 ± 17.0%) of PMR. These results prove that trees can effectively remove fine particles from the air, thereby reducing human exposure to inhalable PM. We proposed a method to estimate the annual amount of PMR on Cedrus deodara, with an average value of 11.9 ± 9.6 t km−2 canopy yr−1 in China. Compared with the load of dust fall (atmospheric particles naturally falling on the ground, average of 138 ± 164 t km−2 land area yr−1 in China), we conclude that trees play a significant role in mitigating haze pollution.

Effect of elevation, season and accelerated snowmelt on biogeochemical processes during isolated conifer needle litter decomposition.

Increased drought and temperatures associated with climate change have implications for ecosystem stress with risk for enhanced carbon release in sensitive biomes. Litter decomposition is a key component of biogeochemical cycling in terrestrial ecosystems, but questions remain regarding the local response of decomposition processes to climate change. This is particularly complex in mountain ecosystems where the variable nature of the slope, aspect, soil type, and snowmelt dynamics play a role. Hence, the goal of this study was to determine the role of elevation, soil type, seasonal shifts in soil moisture, and snowmelt timing on litter decomposition processes. Experimental plots containing replicate deployments of harvested lodgepole and spruce needle litter alongside needle-free controls were established in open meadows at three elevations ranging from 2,800–3,500 m in Crested Butte, Colorado. Soil biogeochemistry variables including gas flux, porewater chemistry, and microbial ecology were monitored over three climatically variable years that shifted from high monsoon rains to drought. Results indicated that elevation and soil type influenced baseline soil biogeochemical indicators; however, needle mass loss and chemical composition were consistent across the 700 m elevation gradient. Rates of gas flux were analogously consistent across a 300 m elevation gradient. The additional variable of early snowmelt by 2–3 weeks had little impact on needle chemistry, microbial composition and gas flux; however, it did result in increased dissolved organic carbon in lodgepole porewater collections suggesting a potential for aqueous export. In contrast to elevation, needle presence and seasonal variability of soil moisture and temperature both played significant roles in soil carbon fluxes. During a pronounced period of lower moisture and higher temperatures, bacterial community diversity increased across elevation with new members supplanting more dominant taxa. Microbial ecological resilience was demonstrated with a return to pre-drought structure and abundance after snowmelt rewetting the following year. These results show similar decomposition processes across a 700 m elevation gradient and reveal the sensitivity but resilience of soil microbial ecology to low moisture conditions.

Effect of sample preparation procedure on standardless wavelength dispersive X-ray fluorescence analysis of plant samples

XRF (X-ray fluorescence analysis) has been applied as the method for analysis of plant samples, but not in its full potential. This method would be highly suitable for monitoring programs and screening studies. A simple sample preparation procedure makes this technique time and cost-effective, although the absence of adequate calibration standards for some analyzed matrices can be a significant limiting factor. Nevertheless, this obstacle can be overcome by the development of the so-called “standardless method” approach. It is important to explore the possibilities and limitations of such method applied to an analysis of plant materials. The accuracy of XRF analysis is highly dependent on the physical characteristics of the sample, which can be significantly affected by the sample preparation procedure. Variations of 3 crucial sample preparation parameters: the mass of the samples (from 1 to 5 g), binder ratio (from 0 to 25% of wax), and pressing pressure (from 10 to 25 t) were tested on needles obtained from two widespread conifer species: Pinus nigra and Abies alba. For most elements, the correlation between the concentration and the change of the binder ratio was statistically significant, while there was no statistically significant correlation between the concentration and the change of the pellet mass and applied pressure. For both types of needles, an estimated systematic error was always higher than a random error. The difference between two types of errors has been higher among samples with different wax content than in samples with different pellet mass, while the variation of applied pressure did not introduce any significant systematic error. On average the change of wax content inflated the value of systematic error by 18 and 13% for the pine and fir needle samples (respectively), while the change of the sample mass has introduced systematic error in lesser extent, on average it was 11% for pine needles and 10% for fir needle samples. The change of pelletizing pressure affected the results by only 3.9% for both conifer needles.

Pinus Species as Prospective Reserves of Bioactive Compounds with Potential Use in Functional Food-Current State of Knowledge.

The pine (Pinus L.) is the largest and most heteromorphic plant genus of the pine family (Pinaceae Lindl.), which grows almost exclusively in the northern hemisphere. The demand for plant-based remedies, supplements and functional food is growing worldwide. Although pine-based products are widely available in many parts of the world, they are almost absent as food ingredients. The literature shows the beneficial effects of pine preparations on human health. Despite the wide geographical distribution of pine trees in the natural environment, there are very few data in the literature on the widespread use of pine in food technology. This study aims to present, characterise and evaluate the content of phytochemicals in pine trees, including shoots, bark and conifer needles, as well as to summarise the available data on their health-promoting and functional properties, and the potential of their use in food and the pharmaceutical industry to support health. Various species of pine tree contain different compositions of bioactive compounds. Regardless of the solvent, method, pine species and plant part used, all pine extracts contain a high number of polyphenols. Pine tree extracts exhibit several described biological activities that may be beneficial to human health. The available examples of the application of pine elements in food are promising. The reuse of residual pine elements is still limited compared to its potential. In this case, it is necessary to conduct more research to find and develop new products and applications of pine residues and by-products.

Terpenes and fungal biomass in the nest mounds of Formica aquilonia wood ants

Nest mounds of wood ants of the Formica rufa group are built using conifer needles, small branches, other plant materials and soil. Conifer needles contain several mono and sesquiterpenes. Thus, wood ant nests may act as terpene hotspots in conifer forest soils. Some of the terpenes show antifungal activity and may thus cause small-scale heterogeneity in fungal biomass. We compared terpene concentrations and fungal biomass (ergosterol concentration) of nest material of the wood ant Formica aquilonia from the top, core and basement of 14 nest mounds in eastern Finland. Overall, α-pinene, camphene, sabinene, β-pinene, myrcene, limonene, camphor and longifolene were detected the most and were commonly present in all the studied layers. We found that terpene concentrations differed between the sampled nest material layers, being generally highest in the core of the nest and lowest at the basement of the nest. There was no association between the terpene concentration and material moisture. Fungal biomass was highest in the top layer, intermediate in core and lowest in basement; however, it was not negatively associated with terpene concentrations. Fungal biomass in nest mounds was positively associated with moisture and alkalinity. Nest mounds of Formica rufa group wood ants are complex structures with different chemical and microbial properties among its layers.