Natural Pine Forests Research Articles

Vegetation Diversity in Native Mixed-Korean Pine Forests

Vegetation Diversity in Native Mixed-Korean Pine Forests

Особенности ассимиляционного аппарата изолированных популяций сосны (Большой Соловецкий остров)

The study results of the assimilation apparatus in the populations of Scots pine (Pinus sylvestris) and Shore pine (Pinus contorta) isolated from the mainland on the Bolshoy Solovetsky Island are presented. Three sites of bilberry pine forest of natural origin, Shore pine and Scots pine in bilberry habitat conditions are presented. Scots pine needle parameters were determined in the pine forest of natural origin and in the cultures of Shore pine. It was revealed that the parameters of the average needle in the natural pine forest and in cultures (Scots pine) are quite similar. The mass of the average needle, width and thickness do not really differ, but only the length and area differ. The mass of needles per branch is also not reliably different. It was revealed that the mass of needles on the branch is 169...181 g, the mass of average needles 14...15 mg, the length totals to 28 and 36 mm in cultures. At the same time, all the parameters are significantly lower than those of pine on the mainland (Primorsky district of the Arkhangelsk region). It was found that the parameters of Shore pine needles in cultures are higher than those of Scots pine in cultures by about 1,5–2 times. The life expectancy of the needles of the Scots pine (determined by weight) is 7 years in natural pine forests and 5 years in cultures. It was revealed that the most significant role is played by needles up to 4 years in the Scots pine and up to 5 years in the Shore pine. It is shown that the length of needles formed in different calendar years differs markedly. It is established that three-year cyclicity is traced in the dynamics of needle length. It was determined that the needle length of the current year is influenced by its size of the previous year. It was revealed that in the studied conditions the position in the crown does not affect the parameters of needles, i. e. the part of the crown (upper, middle, lower) has no influence.

Nitrite-Oxidizing Bacterial Strains Isolated from Soils of Andean Ecosystems and Their Potential Use in Nitrogen Reduction

Nitrification is part of the nitrogen cycle that occurs naturally in ecosystems. It is related to the presence of microorganisms and their metabolism, especially bacteria, which are involved in oxidizing compounds such as NH4+ and NO2− to NO3−. In this study, we evaluated the nitrification potential in 12 bacteria strains that belong to the genera Aeromonas, Bacillus, Buttiauxella, Mycobacterium, Paenibacillus, Serratia, and Yersenia, which are part of the cultivable microbial community from soil in a native forest and pine forest in The Labrado area within the Machangara micro-watershed in the Andes located in the south of Ecuador. This investigation aims to identify heterotrophic and lithoautotrophic strains using specific culture media for ammonium oxidative (AOL-AOH) and nitrate oxidation bacteria (ONL-ONH). The formation of nitrifying halos in the culture media allowed the identification of 10 strains with nitrifying potential. Five strains were from the pine forest, four were isolated from the native forest, and one strain was shared between both forests. The Serratia and Yersinia genera have a high NO2− oxidation capacity. Their inoculation in synthetic water rich in nitrogenous products allowed us to determine 40% and 94% nitrite reduction percentages and cell retention times of 20 to 40 days. Our results are promising for their possible potential use in environmental bioremediation processes through inoculation in wastewater for the biological removal of nitrogenous compounds.

Preliminary Study on Early Diagnosis and Rehabilitation Treatment of Pine Wood Nematode Disease Based on Partial Symptoms

Pine wilt disease (PWD) is greatly serious to Pinus, and there are still no effective therapeutic measures at present. It is necessary to explore a method of early diagnosis of PWD and to study rehabilitation treatment technology for diseased plants diagnosed early. This paper searched for infected pine trees in natural pine forests according to various subtle symptoms and divided the disease development stages. Different doses of 20% emamectin benzoate were injected at different stages, and the symptom development of pine trees was observed after injection. According to different external symptoms, the stage after being infected by PWD was divided into early stage I and II, middle stage I and II, late stage. It was shown by the results that the diagnostic rate of initial diagnosis based on the symptoms of early stage II was as high as 80%. Additionally, for early stage infected pine trees, an injection of 5–10 mL of 20% emamectin benzoate can inhibit the expansion of symptoms of PWD. One year after injection of 20 mL and 10 mL of 20% emamectin benzoate, the residues measured in the lateral branches 4 m above the injection point were 0.18 mg kg−1 and 0.06 mg kg−1, respectively. In summary, the characteristics of early stage II are ideal for identifying early infection, it has a certain therapeutic effect on early infected pine trees by injection of emamectin benzoate.

Planted or Natural Pine Forests, Which One Will Better Recover after Drought? Insights from Tree Growth and Stable C and H Isotopes

Increasing intensity and frequency of droughts are leading to forest dieback, growth decline and tree mortality worldwide. Reducing tree-to-tree competition for water resources is a primary goal for adaptive climate silviculture strategies, particularly in reforested areas with high planting density. Yet, we need better insights into the role of stand type (i.e., natural forests versus plantations) on the resilience of pine forests to droughts across varying time scales. In this study, we combined dendrochronological data and stable C (δ13C) and H (δ2H) isotopes measured in tree-ring wood as well as in specific wood chromatographically isolated compounds to investigate contrasting responses to drought of natural versus planted stands of two representative pine species, i.e., Pinus pinaster and Pinus nigra in southeastern Europe. Natural stands exhibited about two-fold increase in tree-ring growth in average (basal area at 20 years-BAI20) as compared to planted stands. A response function analysis showed contrasting seasonal growth patterns for both species, which were related to monthly mean temperature and precipitation. Both stand type and species variables influenced growth resilience indices. Both pine species revealed contrasting resilience patterns among forest types; whereas planted stands seemed to be less sensitive to yearly droughts as determined by a higher recovery index (CRc) for P. pinaster, the contrary was found in the case of P. nigra. On the other hand, while resistance CRT and resilience CRS indices were higher for planted than natural forests in the case of P. pinaster, little differences were found for P. nigra. Beyond comparisons, carbon stable isotopes shed lights on the role of forest types in dry sites, being δ13C consistently lower in natural than in planted forests for both pine species (p < 0.05). We concluded that planted forest assimilated more carbon as per unit of water used than natural stands in response to droughts. Both δ13C and δ2H isotopic signals were positively correlated for both species for planted forests. However, a lack of correlation was evidenced for natural stands. Consistent with δ13C observations, δ2H concentrations in woody phenolic compounds (guaiacol and oleic acid) revealed contrasting patterns among forest types. This puts forward that δ2H concentrations in woody phenolic compounds (rather than in woody tree ring) accounts for other confounding factors in tree ring formation that can be associated with forest type. Our results highlight the value of stable isotope approaches versus conventional dendrochronological tools in drought studies and call for the consideration of forest type as an endogenous aspect defining the vulnerability of pine forests to climate.

Multispecies comparison of host responses to Fusarium circinatum challenge in tropical pines show consistency in resistance mechanisms.

Fusarium circinatum poses a threat to both commercial and natural pine forests. Large variation in host resistance exists between species, with many economically important species being susceptible. Development of resistant genotypes could be expedited and optimised by investigating the molecular mechanisms underlying host resistance and susceptibility as well as increasing the available genetic resources. RNA-seq data, from F. circinatum inoculated and mock-inoculated ca. 6-month-old shoot tissue at 3- and 7-days postinoculation, was generated for three commercially important tropical pines, Pinus oocarpa, Pinus maximinoi and Pinus greggii. De novo transcriptomes were assembled and used to investigate the NLR and PR gene content within available pine references. Host responses to F. circinatum challenge were investigated in P. oocarpa (resistant) and P. greggii (susceptible), in comparison to previously generated expression profiles from Pinus tecunumanii (resistant) and Pinus patula (susceptible). Expression results indicated crosstalk between induced salicylate, jasmonate and ethylene signalling is involved in host resistance and compromised in susceptible hosts. Additionally, higher constitutive expression of sulfur metabolism and flavonoid biosynthesis in resistant hosts suggest involvement of these metabolites in resistance.

Relationship between the initial number of carried Bursaphelenchus xylophilus and its transmission by Monochamus carolinensis with reference to virulence

Summary The pine wood nematode (PWN), Bursaphelenchus xylophilus, is the causative agent of pine wilt disease and is transmitted by cerambycid adults of the genus Monochamus. It is believed to have been introduced into Japan from North America in the 1900s and since then it has been devastating the native pine forests. By contrast, the epidemics of the disease have never occurred in pine forests native to North America in the original habitats, indicating no expression of virulence. To determine the evolutionary change in the transmission traits of PWN, the temporal pattern of PWN transmission to fresh branch sections of Pinus sylvestris was studied using 38 Monochamus carolinensis adults in Illinois, USA, and compared with previous studies on the PWN-M. alternatus and B. mucronatus-M. saltuarius systems in Japan. A great difference was observed in the initial nematode load among vectors irrespective of the three systems. The maximal numbers of PWN transmitted (5 days)−1 by individual vectors were greater and the efficiencies of nematode transmission and invasion were higher for the Japanese PWN-M. alternatus system than for the North American PWN-M. carolinensis system in two heavy classes of initial load of over 1000 nematodes. The proportion of PWN transmitted to healthy pine trees by reproductively immature female vectors was small (2.5-11.5%) in the three nematode-vector systems in most cases. The evolutionary changes in the transmission traits and the control of the range expansion of the PWN were discussed in relation to the expression of virulence.

Comparative Genomics of Fusarium circinatum Isolates Used to Screen Southern Pines for Pitch Canker Resistance.

Pitch canker, caused by the fungal pathogen Fusarium circinatum, is a global disease affecting many Pinus spp. Often fatal, this disease causes significant mortality in both commercially grown and natural pine forests and is an issue of current and growing concern. F. circinatum isolates collected from three locations in the U.S. state of Florida were shown to be virulent on both slash and loblolly pine, with two of the isolates causing equivalent and significantly larger lesions than those caused by the third isolate during pathogenicity trials. In addition, significant genetic variation in lesion length in the pedigreed slash pine population was evident and rankings of parents for lesion length were similar across isolates. Experimental data demonstrate that both host and pathogen genetics contribute to disease severity. High-quality genomic assemblies of all three isolates were created and compared for structural differences and gene content. No major structural differences were observed among the isolates; however, missing or altered genes do contribute to genomic variation in the pathogen population. This work evaluates in planta virulence among three isolates of F. circinatum, provides genomic resources to facilitate study of this organism, and details comparative genomic methods that may be used to explore the pathogen's contribution to disease development.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Vegetation of regional landscape and botanical natural monument «Aland’s Pine Forest» (Kvarkensky area of the Orenburg Region)

The paper presents a detailed analysis of regional landscape and botanical natural monument Alands Pine Forest (Kvarkensky area of the Orenburg Region) vegetation. The pine forest vegetation has rather high phytodiversity and dominance indexes. 71 plant vascular species have been identified (3 of them are included in the Red Book of the Orenburg Region (2019)) and 15-species pine communities prevail, but steppe species dominate in shrub and herb layers. The authors have revealed that the described pine forests are forest-steppe amphycoenosis. 13 plant associations have been identified by multivariate statistics methods, but their biotopes are not specific by fundamental abiotic factors. The authors have also established that forest conditions of Alands Pine Forest are of AB₁ and AB₁₋₂ types and light type of stand of trees structure by A.L. Betgard steppe forest typology. The detected pine vegetation associations form ordination series - sylvatic of steppe pine forest with wheat-grass ( Elytrigia repens (L.) Nevski) and amphycoenotic of steppe pine forest with steppe herbs. The principal abiotic factors for pine forests coenotic structure forming are soil calcium and nitrogen regimes, soil moistening and acidity and porosity (aeration) of soils. Factors of biotope discrimination are thermal climate (radiation balance), cryoclimate (negative winter temperature), brightness regime and saline regime of soils.

Millennial-Scale Carbon Storage in Natural Pine Forests of the North Carolina Lower Coastal Plain: Effects of Artificial Drainage in a Time of Rapid Sea Level Rise

Coastal forested wetlands provide important ecosystem services along the southeastern region of the United States, but are threatened by anthropogenic and natural disturbances. Here, we examined the species composition, mortality, aboveground biomass, and carbon content of vegetation and soils in natural pine forests of the lower coastal plain in eastern North Carolina, USA. We compared a forest clearly in decline (termed “ghost forest”) adjacent to a roadside canal that had been installed as drainage for a road next to an adjacent forest subject to “natural” hydrology, unaltered by human modification (termed “healthy forest”). We also assessed how soil organic carbon (SOC) accumulation changed over time using 14C radiocarbon dating of wood sampled at different depths within the peat profile. Our results showed that the ghost forest had a higher tree density at 687 trees ha−1, and was dominated by swamp bays (Persea palustric), compared to the healthy forest, which had 265 trees ha−1 dominated by pond pine (Pinus serotina Michx). Overstory tree mortality of the ghost forest was nearly ten times greater than the healthy forest (p < 0.05), which actually contributed to higher total aboveground biomass (55.9 ± 12.6 Mg C ha−1 vs. 27.9 ± 8.7 Mg ha−1 in healthy forest), as the dead standing tree biomass (snags) added to that of an encroaching woody shrub layer during ecosystem transition. Therefore, the total aboveground C content of the ghost forest, 33.98 ± 14.8 Mg C ha−1, was higher than the healthy forest, 24.7 ± 5.2 Mg C ha−1 (p < 0.05). The total SOC stock down to a 2.3 m depth in the ghost forest was 824.1 ± 46.2 Mg C ha−1, while that of the healthy forest was 749.0 ± 170.5 Mg C ha−1 (p > 0.05). Carbon dating of organic sediments indicated that, as the sample age approaches modern times (surface layer year 2015), the organic soil accumulation rate (1.11 to 1.13 mm year−1) is unable to keep pace with the estimated rate of recent sea level rise (2.1 to 2.4 mm year−1), suggesting a causative relationship with the ecosystem transition occurring at the site. Increasing hydrologic stress over recent decades appears to have been a major driver of ecosystem transition, that is, ghost forest formation and woody shrub encroachment, as indicated by the far higher overstory tree mortality adjacent to the drainage ditch, which allows the inland propagation of hydrologic/salinity forcing due to SLR and extreme storms. Our study documents C accumulation in a coastal wetland over the past two millennia, which is now threatened due to the recent increase in the rate of SLR exceeding the natural peat accumulation rate, causing an ecosystem transition with unknown consequences for the stored C; however, much of it will eventually be returned to the atmosphere. More studies are needed to determine the causes and consequences of coastal ecosystem transition to inform the modeling of future coastal wetland responses to environmental change and the estimation of regional terrestrial C stocks and flux.

Effect of Plant Diversity on the Occurrence of Diplodia Tip Blight in Natural Secondary Japanese Red Pine Forests

Diplodia tip blight caused by Sphaeropsis sapinea (Fr.) Dyko and B. Sutton is a serious threat to the health of natural secondary Japanese red pine (Pinus densiflora Sieb. et Zucc.) forests. To explore the effect of plant diversity on Diplodia tip blight disease occurrence, the correlation between Diplodia tip blight in P. densiflora and plant diversity in various stand types and vertical structure layers were analyzed by Pearson correlation coefficients and generalized linear model while keeping environmental factors relatively consistent. Disease index of Diplodia tip blight in P. densiflora was positively correlated with the plant diversity indices in the tree layers of P. densiflora–conifer mixed forest. In contrast, it was negatively correlated with the plant diversity indices in the tree layers of P. densiflora–hardwood mixed forest and P. densiflora pure forest. In shrub–herb layers of all stands except the P. densiflora pure forest herb layer, the disease index was positively correlated with the plant diversity indices. The prediction models for the disease index of Diplodia tip blight in the P. densiflora–hardwood mixed forest, P. densiflora–conifer mixed forest, and P. densiflora pure forest were also established. The foregoing results suggest that in the Kunyu Mountains of China, the differences in plant diversity among various stand types and vertical structure layers have different effects on the occurrence of Diplodia tip blight in P. densiflora. Plant diversity largely reflects the occurrence of Diplodia tip blight disease. However, if the effect of plant diversity on Diplodia tip blight is fully reflected, the plant species characteristics, especially tree genetic relationships, should be considered. In this way, plant species diversity structure in natural secondary Japanese red pine forests may be modified through forest management to lower the incidence of Diplodia tip blight.

Molecular characterization and phylogenetic analyses of Lophodermella needle pathogens (Rhytismataceae) on Pinus species in the USA and Europe.

Increasing prevalence of conifer needle pathogens globally have prompted further studies on pathogen identification and a better understanding of phylogenetic relationships among needle pathogens. Several Lophodermella species can be aggressive pathogens causing needle cast in natural pine forests in the USA and Europe. However, their relationships with other Rhytismataceae species have historically been based on similarities of only limited phenotypic characters. Currently, no molecular studies have been completed to elucidate their relationships with other Lophodermella needle pathogens. This study collected and sequenced three gene loci, namely: internal transcribed spacer, large ribosomal subunit, and translation elongation factor 1-alpha, from five Lophodermella needle pathogens from North America (L. arcuata, L. concolor, L. montivaga) and Europe (L. conjuncta and L. sulcigena) to distinguish phylogeny within Rhytismatacaeae, including Lophophacidium dooksii. Phylogenetic analyses of the three loci revealed that all but L. conjuncta that were sampled in this study consistently clustered in a well-supported clade within Rhytismataceae. The multi-gene phylogeny also confirmed consistent nesting of L. dooksii, a needle pathogen of Pinus strobus, within the clade. Potential synapomorphic characters such as ascomata position and ascospore shape for the distinct clade were also explored. Further, a rhytismataceous species on P. flexilis that was morphologically identified as L. arcuata was found to be unique based on the sequences at the three loci. This study suggests a potential wider range of host species within the genus and the need for genetic characterization of other Lophodermella and Lophophacidium species to provide a higher phylogenetic resolution.

TYPOLOGICAL STRUCTURE OF FORESTS IN THE DESNA CATCHMENT AREA

A general characterization of the catchment area of the River Desna is given. The Desna catchment area is located in two forest zones of Ukraine - Polissia, and Lisostep. According to the results from the analysis of the forest inventory database of PA Ukrderzhlisproekt, the planted areas of the Desna catchment area have been distributed by forest site types, forest types, tree species. To analyze the typological structure of the Desna catchment area, the sites belonging to the catchment area have been selected from the standwise forest inventory database of PA Ukrderzhlisproekt. The total area of the stand sample is 395.3 thousand hectares. The catchment area boundary has been determined using MapInfo Professional 12.5 and a vector map of Ukraine. The forest areas are distributed by administrative regions as follows: Chernihiv Region (62 %), Sumy Region (31 %), Kyiv Region (7 %). The forest resources of the Desna catchment area are characterized by a wide variety of types of forest sites covering almost the entire Ye.V. Alekseev’s and P.S. Pogrebnyak’s edaphic grid. In each group of forest site types, the foresters have identified different numbers of forest types. Pine forests (bors) are represented by five, pine – fir/oak forests (subors) - by eight, pine forests with birch, aspen and oak participation (composite subors) – by twenty eight and oak groves (dubravas) – by eighteen types of forest. In total, 59 types of forest are identified, including four - arid, thirteen - fresh, eighteen - sodden, nineteen - wet and five - bog. The most common types of forest within the area of the study subject are as follows: fresh fir/oak forest (subor) (40 %), fresh lime/oak/pine forest (composite subor) (9 %), sodden fir/oak forest (subor) (7 %), fresh pine forest (bor) (7 %). Among the tree species, the following species predominate common pine (60 %) and common oak (15%). The weighted average forest inventory indicators of natural and artificial pine forests in the conditions of fresh oak/pine forest (subor) in the Desna catchment area have been determined and analysed. It has been established that natural pine forests, as pertaining to reserves (per 1 m3•ha-1) up to the 5th age class, predominate over artificial pine forests, and, in contrast, as for the 6th to the 13th and further age classes, the artificial pine forests predominate over the natural ones. While planning, organization, and forest management in compliance with watershed and landscape principle, one should take into account the following varieties: forest types, types of forest stands, categorization of forest protectability in the watersheds of Desna River.

Detection of Pine Cones in Natural Environment Using Improved YOLOv4 Deep Learning Algorithm.

Achieving the rapid and accurate detection of pine cones in the natural environment is essential for yield estimation and automatic picking. However, the complex background and tiny target pose a significant challenge to pine cone detection. This paper proposes a pine cone detection method using the improved You Only Look Once (YOLO) version 4 algorithm to overcome these challenges. First, the original pine cone image data come from a natural pine forest. Crawler technology is utilized to collect more pine cone images from the Internet to expand the data set. Second, the densely connected convolution network (DenseNet) structure is introduced in YOLOv4 to improve feature reuse and network performance. In addition, the backbone network is pruned to reduce the computational complexity and keep the output dimension unchanged. Finally, for the problem of feature fusion at different scales, an improved neck network is designed using the scale-equalizing pyramid convolution (SEPC). The experimental results show that the improved YOLOv4 model is better than the original YOLOv4 network; the average values of precision, recall, and AP reach 96.1%, 90.1%, and 95.8%; the calculation amount of the model is reduced by 21.2%; the detection speed is fast enough to meet the real-time requirements. This research could serve as a technical reference for estimating yields and automating the picking of pine cones.

Classification of the Mediterranean lowland to submontane pine forest vegetation

AbstractAimVegetation types of Mediterranean thermophilous pine forests dominated by Pinus brutia, Pinus halepensis, Pinus pinaster and Pinus pinea were studied in various areas. However, a comprehensive formal vegetation classification of these forests based on a detailed data analysis has never been developed. Our aim is to provide the first broad‐scale classification of these pine forests based on a large data set of vegetation plots.LocationSouthern Europe, North Africa, Levant, Anatolia, Crimea and the Caucasus.MethodsWe prepared a data set of European and Mediterranean pine forest vegetation plots. We selected 7,277 plots dominated by the cold‐sensitive Mediterranean pine species Pinus brutia, Pinus halepensis, Pinus pinaster and Pinus pinea. We classified these plots using TWINSPAN, interpreted the ecologically and biogeographically homogeneous TWINSPAN clusters as alliances, and developed an expert system for automatic vegetation classification at the class, order and alliance levels.ResultsWe described Pinetea halepensis as a new class for the Mediterranean lowland to submontane pine forests, included in the existing Pinetalia halepensis order, and distinguished 12 alliances of native thermophilous pine forests, including four newly described and three informal groups merging supposedly native stands and old‐established plantations. The main gradients in species composition reflect elevational vegetation belts and the west–east, and partly north–south, biogeographical differences. Both temperature and precipitation seasonality co‐vary with these gradients.ConclusionsWe provide the first formal classification at the order and alliance levels for all the Mediterranean thermophilous pine forests based on vegetation‐plot data. This classification includes traditional syntaxa, which have been critically revised, and a new class and four new alliances. We also outline a methodological workflow that might be useful for other vegetation classification syntheses. The expert system, which is jointly based on pine dominance and species composition, is a tool for applying this classification in research and nature conservation survey, monitoring and management.

Development of a Field Deployable Firebrand Flux and Condition Measurement System

A new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

Responses of forest carbon and water coupling to thinning treatments from leaf to stand scales in a young montane pine forest

BackgroundWater-use efficiency (WUE) represents the coupling of forest carbon and water. Little is known about the responses of WUE to thinning at multiple spatial scales. The objective of this research was to use field measurements to understand short-term effects of two thinning treatments (T1: 4500 stems ha−1; and T2: 1100 stems ha−1) and the control (NT: 27,000 stems ha−1) on WUE at the three spatial scales (leaf level: the ratio of leaf photosynthesis to leaf transpiration; tree-level: tree growth to tree transpiration; and stand level: net primary production (NPP) to stand transpiration) and intrinsic WUEi (the ratio of leaf photosynthesis to stomatal conductance at leaf-level; and NPP to canopy conductance at stand-level) in a 16-year old natural lodgepole pine forest. Leaf-level measurements were conducted in 2017, while tree- and stand-level measurements were conducted in both 2016 (the normal precipitation year) and 2017 (the drought year).ResultsThe thinning treatments did not significantly affect the tree- and stand-level WUE in the normal year of 2016. However, the thinning significantly affected WUE in the drought year of 2017: T2 exhibited significantly higher tree-level WUE (0.49 mm2 kg−1) than NT (0.08 mm2 kg−1), and compared to NT, the stand-level WUE values in the thinned stands (T1 and T2) were significantly higher, with means of 0.31, 0.56 and 0.70 kg m−3, respectively. However, the leaf-level and stand-level WUEi in the thinned stands in the drought year were significantly lower than those in the unthinned stands. No significant differences in the leaf-level WUE were found among the treatments in 2017. In addition, the thinning did not significantly change the WUE-VPD relationships at any studied spatial scale.ConclusionsThe thinning treatments did not cause significant changes in all studied WUE metrics in a normal year. However, their effects were significantly promoted under the drought conditions probably due to the decrease in soil water availability, demonstrating that thinning can improve WUE and consequently support forests to cope with the drought effects. The inconsistent results on the effects of the thinning on forest carbon and water coupling at the spatial scales and the lack of the consistent WUE metrics constraint across-scale comparison and transferring of WUE.

Proteometabolomic characterization of apical bud maturation in Pinus pinaster.

Bud maturation is a physiological process that implies a set of morphophysiological changes that lead to the transition of growth patterns from young to mature. This transition defines tree growth and architecture, and in consequence traits such as biomass production and wood quality. In Pinus pinaster Aiton, a conifer of great timber value, bud maturation is closely related to polycyclism (multiple growth periods per year). This process causes a lack of apical dominance, and consequently increased branching that reduces its timber quality and value. However, despite its importance, little is known about bud maturation. In this work, proteomics and metabolomics were employed to study apical and basal sections of young and mature buds in P. pinaster. Proteins and metabolites in samples were described and quantified using (n)UPLC-LTQ-Orbitrap. The datasets were analyzed employing an integrative statistical approach, which allowed the determination of the interactions between proteins and metabolites and the different bud sections and ages. Specific dynamics of proteins and metabolites such as histones H3 and H4, ribosomal proteins L15 and L12, chaperonin TCP1, 14-3-3 protein gamma, gibberellins A1, A3 and A8, strigolactones and abscisic acid, involved in epigenetic regulation, proteome remodeling, hormonal signaling and abiotic stress pathways showed their potential role during bud maturation. Candidates and pathways were validated employing interaction databases and targeted transcriptomics. These results increase our understanding of the molecular processes behind bud maturation, a key step towards improving timber production and natural pine forests management in a future scenario of climate change. However, further studies are necessary using different P. pinaster populations that show contrasting wood quality and stress tolerance in order to generalize the results.

Occurrence of Dothistroma needle blight in Lithuania and Belarus: The risk posed to native Scots Pine forests

AbstractDothistroma needle blight (DNB) caused by the ascomycetous fungus Dothistroma septosporum is an important pine disease in Europe. In this study, we determined the distribution and abundance of D. septosporum in local Scots pine forests and plantations in Lithuania and neighbouring Belarus by combining morphological observations and molecular tools. This is the first valid report on the occurrence of D. septosporum in Belarus, based on detailed morpho‐cultural and molecular characteristics. Currently, in both countries only the asexual stage of D. septosporum is found on needles of the native Scots pine and on various ornamental exotic pines planted in botanical gardens and arboreta. Our results show that P. sylvestris may now be considered the most common host with varying susceptibility to D. septosporum. Phylogenetic analysis revealed the presence of three different ITS haplotypes among Lithuanian and Belarusian D. septosporum isolates. Mating type (MAT) genes analysis showed that two mating types (MAT1‐1 and MAT1‐2) occur in both countries, indicating a high probability of D. septosporum sexual reproduction. Isolates from Lithuania were represented by the idiomorph MAT1‐1 and MAT1‐2 in the ratio of 1:1, while isolates from Belarus were dominated by the idiomorph MAT1‐1 (ratio 3:1). Our results also demonstrate the importance of DNB monitoring for prevention and control of disease outbreaks in Lithuanian and Belarusian Scots pine forests in the future.

Using dendrogeomorphology to estimate soil erosion in mixed native species and pine forests on Ultisols in Piracicaba, Brazil

This work aims to study and date the erosion process in a gully located at the Experimental Station of Tupi (Piracicaba, São Paulo, Brazil) using dendrogeomorphology. Dendrogeomorphology is a relatively new science that relates the growth of tree-rings with geomorphological processes allowing chronological reconstruction and occurrence of events. The relevance of this study is to know the potential of this science in tropical areas because currently this type of study is lacking in these areas. This technique was applied using exposed roots of species of Pinus ssp. The dating of the erosion process was based on the changes in the pattern of root growth, such as the width of the ring, eccentric growth, percentage of latewood and density of the wood that occur after exposure by erosion. Through the study of these changes the first year of root exposure was determined, and the annual rate of erosion was estimated. Erosion rates of 0.65 and 2.39 m/year were found, characterizing the longitudinal advancement of the gully. Finally, dendrogeomorphology demonstrates great potential as a tool in tropical areas. The data and information obtained can be translated into a dendrogeomorphological database and contribute to the expansion of this science in Brazil and areas of tropical environments.