Natural Pine Research Articles

Депонирование углерода стволовой фракцией в 100-летних лесных культурах хвойных пород

The paper presents the study results of the atmospheric carbon deposition by the main forest-forming coniferous species, namely European larch and Scots pine, in two forest monitoring sites represented by 100-year-old forest plantations on the territory of the Nikolskaya forest dacha (north-east of the Moscow region) under typical conditions of native fresh blueberry pine forests (B2). It was analyzed that the forest plantations of European larch in terms of the total phytomass of the trunk significantly exceed that of forest plantations of Scots pine, where it turned out to be 34 % less in the latter than in the artificial larch stand; in the total phytomass of the trunk, the proportion of the larch bark fraction was 13,2 %, and in pine cultures — 7,6 %. A clear advantage in carbon deposition of European larch over such a native species as Scots pine was determined, which is actually expressed by a twofold excess in accumulated carbon, which indicates a highly desirable use of European larch as a valuable introduced species for the creation of forest plantations. It has been established that the climatypes of the genus Larix in the geographical plantings of the mixed forest zone, represented by European, Polish and Sukachev’s larch, achieve the maximum silvicultural effect. It is concluded that the deposited carbon correlates with the phytomass of the forest stand, which, in turn, correlates with the stock of stem wood. Knowing the stock of stem wood, to a certain extent one can consider the stock of deposited carbon.

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.

Xylem formation patterns from Mediterranean to subalpine climate conditions reveal high growth plasticity of pine species on Corsica

Key messageBlack pine and Maritime pine exhibit considerable differences in growth phenology across elevation belts with a 1-month delay for xylogenesis and increasing growth rates from low, mid to high elevations.Investigating seasonal wood formation is crucial to understand tree growth responses to climate impact. The present study quantifies the variability of xylogenesis along an elevation gradient on the Mediterranean island of Corsica, where two native pine species (Pinus nigra Arnold ssp. laricio Maire and Pinus pinaster Aiton) grow from the upper tree line to sea level, partly in sympatry. We extracted microcores from 35 trees at 5 sites along an East–West transect from the coasts (10 m asl) to the island's central mountain ridge (1600 m asl) during bi-weekly sampling campaigns between 2017 and 2019. We applied generalised additive models to detect radial growth differences in elevation and species along with minimum temperatures for growth initiation. We found that trees in low elevations experienced over 2 months longer growth periods with higher maximum growth rates than in high elevations. The results show a 1-month delay for the beginning of tracheid formation between the low, mid and high-elevation belts but comparable timing for its termination. At the sites where both species co-occur, P. nigra accumulates more radial cells in a shorter time than P. pinaster. Trees at the two contrasting coastal sites have similar growth period lengths, but exhibit a time shift of over a month. Minimum temperatures around growth initiation vary between 3.1 °C for P. nigra and 9.9 °C for P. pinaster. These findings emphasise the high plasticity in the growth behaviour of one of the most widespread tree genera in Mediterranean and temperate zones.

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.

Structure of Microscopic Fungal Species in Soils at Amber Mining Territories before and during the use of New Technology of Pine Plantation Formation.

Introduction: Ukraine is one of the European leaders in amber deposits. The main deposits of the mineral are concentrated in the forests of the Rivne, Zhytomyr and Volyn regions. As a result of the extraction process, the integrity of forest’s ecosystems is violated, the fertile soil layer is destroyed, and 3.5 thousand hectares of forests have to be restored. Aim: Evaluation of different forest management strategies in degraded soil regeneration. Objective: The study aims to explore the response of soil mycobiota to extreme conditions associated with amber mining and to propose biotechnology to restore the fertile soil layer by methods of regenerative land use, namely the use of biomass of various ways of birch cuts, which is the primary succession to the indigenous pine stands in the region. Materials and Methods: The study was carried out on the territory of the Klesiv amber deposit in the Ukrainian Polissya. The bioindication method with the help of soil micromycetes was used to assess the quality of the plant development environment in the conditions of ecosystem restoration after amber extraction. To determine the species composition of hyphomycetes, the method of serial dilutions and direct seeding on agar media of soil suspensions was used. The analysis of soil mycobiota was performed using quantitative ecology methods. The method of correlation groups was used to determine the taxonomic diversity of hyphomycetes. To determine the effectiveness of the restoration of the studied forest soils, the express analysis of the content of essential nutrients using NPK-sensor was used. Standard methods for the determination of mobile phosphorus, potassium and nitrogen compounds were used as controls. Results: The species composition and taxonomic characteristics of soil micromycetes of forest ecosystems disturbed by amber mining have been studied. It was found that in the areas of amber mining, soil micromycetes form linear connections and three-membered structures, which is characteristic of disturbed biocenoses. In the 60-year-old plantation, soil micromycetes form strong six-membered structures that are characteristic of menopausal ecosystems or intact biocenoses. The biotechnology of restoration of the indigenous plantation characteristic of these conditions - pine with an admixture of hanging birch is offered. The result of the application of this technology will allow to reproduce natural forest ecosystems in large areas. Conclusion: For the first time, the structure of fungal complexes in the areas of amber mining has been determined, which indicates that the formation of a stable structure requires time and a systematic approach to the restoration of damaged soils. In the soils disturbed by amber mining, initial linear, three-membered and four-membered structures were formed, the structural genera of which are the “pioneer genera” Penicillium, Mucor, Rhizopus, the species of which were the first to inhabit plant remains. In the process of reforestation in areas affected by amber mining, biotechnology was used for the first time, which involved the formation of natural pine stands by cutting birch, forming the primary succession in the studied areas. The comparison of the results of chemical analysis of soils of the studied areas of the Klesiv forestry before and after the application of birch pruning technology for the formation of pine stands proves the effectiveness of the technology, as in all areas nitrogen, phosphorus and potassium were increased in the soil.

A class of natural pinus koraiensis population system with time delay and diffusion term

In this paper, we consider the long-term sustainability of the northeast Korean pine. We propose a class of natural Korean pine population system with time delay and diffusion term. First, by analyzing the roots distribution of the characteristic equation, we study the stability of the model system with diffusion terms and prove the occurrence of Hopf bifurcation. Second, we introduce lactation time delay into a population model with a diffusion term, based on stability theory of ordinary differential equation, norm form methods and center manifold theorem, the stability of bifurcating periodic solutions and the relevant formula for the direction of Hopf bifurcation are given. Finally, some numerical simulations are given.

Checking the balance between pathogenic and mutualistic pine needle fungi of the genus Lophodermium in forested and urban areas of Slovakia

ABSTRACT Lophodermium species are well known to be among the dominant endophytic fungi colonizing pine needles. The occurrence of two species with different life strategies on different Pinus trees across Slovakia was detected by PCR using species-specific primers. In general, the commensalistic species L. pinastri was more frequent than parasitic L. seditiosum. There were no significant differences observed between urban and natural environments, but natural environments have more frequent colonization by L. pinastri and less frequent were trees negatively tested to Lophodermium colonization. Among the most frequently sampled trees were non-native P. nigra and native P. sylvestris. A significant difference in Lophodermium incidence was detected between these two species in a natural environment, with increased frequency of L. pinastri on native Scots pine. In addition to one clade of L. pinastri, culture based species identification confirmed the presence of L. corconticum and an undescribed clade of L. seditiosum that is not sensitive to used PCR primers for the species detection.

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.

Effects of Soil Nutrients on Plant Nutrient Traits in Natural Pinus tabuliformis Forests.

In light of global warming, the interaction between plant nutrient traits and soil nutrients is still unclear. Plant nutrient traits (e.g., N and P) and their stoichiometric relationships (N/P ratio) are essential for plant growth and reproduction. However, the specific role of soil nutrients in driving variation in plant nutrient traits remains poorly understood. Fifty natural Pinus tabuliformis forests were used as the research object to clarify the interaction between plant nutrient traits and soil nutrients. We show that: (1) The Nmass, Pmass and N/P ratios of leaves were significantly higher than those of roots. The N/P ratio of both leaves and roots was less than 14. (2) Leaf nutrient traits showed diverse relationship patterns with root nutrient traits throughout the growing period. Significant changes were found in root nutrient PC2 (the second principal component of root nutrient traits) and leaf nutrient PC1 (the first principal component of leaf traits), and non-significant changes were found in other relationships between leaf and root traits (p > 0.05). Root nutrient traits explained 36.4% of the variance in leaf nutrient traits. (3) With the increase in soil nutrient PC2 (related to N), leaf PC2 (related to N) showed a significant trend of first decreasing and then increasing (p < 0.05). Only the soil Nmass was significantly correlated with the leaf Nmass (p < 0.05), which demonstrated that the growth and survival of Pinus tabuliformis forests were mainly affected by N-limitation.

‘Pine Decline or pine declines?’ Analysis and Interpretation of Bog-Pines from Wem Moss, Shropshire, UK

A dendrochronological investigation was undertaken on subfossil Scots pine (Pinus sylvestris L.) stumps following their discovery during conservation management at Wem Moss, a small (28 ha) former raised mire in Shropshire, UK. Two ring-width chronologies were constructed from 14 of the 17 trees sampled spanning 198 and 208 years, respectively. Whilst dendrochronological dating was not possible, radiocarbon assays provided an estimated age for this mire-rooting woodland of between 3015 and 2505 years cal. BCE, coinciding with the age traditionally associated with the widespread mortality of pine trees throughout much of the UK and Ireland, often referred to as the Pine Decline (ca. 4000 radiocarbon years BP). Placed in a wider geographical context, the Wem Moss pines are located within the lowland Meres and Mosses region, where previous studies on subfossil pine have demonstrated protracted declines in mire-rooting trees. These have included tree mortality significantly post-dating the Pine Decline, especially at larger peatland sites that exceed 5 km2. Such macrofossil evidence for the presence of Scots pine into the late Holocene is supported by continuous Pinus pollen representation at peatland sites in the Welsh Marches (English–Welsh border), suggesting the possible survival of native Scots pine trees in this area up to the present day. The investigation of Wem Moss bog pines and their wider geographical context highlights the incomplete and patchy nature of palaeo-vegetational records and also the need for future genetic research on living Scots pine in possible refugial areas in Britain and Ireland.

Frequency distribution of the initial number of Bursaphelenchus xylophilus carried by adult Monochamus carolinensis in Illinois, with reference to that by M. alternatus in Japan

Summary The pine wood nematode (PWN), Bursaphelenchus xylophilus, is the causative agent of pine wilt disease and is transmitted primarily by cerambycid adults of the genus Monochamus. It is believed to have been introduced into Japan from North America in the 1900s and confirmed to have invaded western Europe in 1999. The nematode has been devastating pine forests in invaded areas because the native pine species are susceptible. This study examined the number of PWN carried by individual M. carolinensis adults (initial PWN load) immediately after emerging from dead Pinus sylvestris and P. strobus trees in Illinois, USA. The data were compared with the initial PWN load on M. alternatus adults emerging from dead P. thunbergii trees in Japan ca 80 years after the PWN invasion. When the zero-inflated negative binomial model was fitted to the initial PWN loads it provided three results. First, the PWN exhibited clumped distributions among vectors in the PWN-M. carolinensis-P. sylvestris or P. strobus system in Illinois and the PWN-M. alternatus-P. thunbergii system in Japan. Second, there was no difference in the frequency distribution of the initial PWN load between the three disease systems. Third, the initial PWN load increased as the overwintering PWN density in wood or the adult body mass increased, whereas it decreased as the emergence date of vectors increased. Consequently, the frequency distribution of initial PWN load exhibited no evolutionary change in Japan and the initial PWN load was considered to be determined by environmental factors and conditions.

Two novel endophytic Tolypocladium species identified from native pines in south Florida

Supplementary information:&lt;br /&gt;Fig. S1. Alignment used to construct the concatenated phylogenetic tree.&lt;br /&gt;Fig. S2. Alignment used to construct the ITS phylogenetic tree.&lt;br /&gt;Fig. S3. Phylogram of Tolypocladium species collected in this study and previously described generated from Maximum likelihood analysis of ITS sequence alignment. Bootstrap support (BS) values &gt; 75 % are indicated.&lt;br /&gt;Table S1. Strains used to construct the multilocus phylogeny.Information on isolation source and GenBank accession numbers.

Stability of C:N:P Stoichiometry in the Plant–Soil Continuum along Age Classes in Natural Pinus tabuliformis Carr. Forests of the Eastern Loess Plateau, China

Ecological stoichiometry is useful for revealing the biogeochemical characteristics of flows of nutrients and energy between plant and soil, as well as the important implications behind these ecological phenomena. However, the ecological stoichiometric linkages among leaf, litter, soil, and enzymes in the natural forests of the Loess Plateau remain largely unknown. Here, leaf, litter, and soil samples were collected from four age classes of natural Pinus tabuliformis Carr. (P. tabuliformis) to explore the deep linkages among these components. We measured the total carbon (C), total nitrogen (N), and total phosphorus (P) concentrations of leaf and litter, as well as the concentrations of soil organic C, total N, total P, nitrate N, ammonium N, available P, and the activities of β-1,4-glucosidase (a C-acquiring enzyme), β-1,4-N-acetylglucosidase (an N-acquiring enzyme), and alkaline phosphatase (a P-acquiring enzyme) in the topsoil (0–20 cm). The average leaf N:P was 6.9 indicated the growth of P. tabuliformis was constrained by N according to the relative resorption theory of nutrient limitation. The C:N, C:P, and N:P ratios in leaf, litter, and soil and the enzyme activity were not significantly different among age classes (p &gt; 0.05). Litter C:N (43.3) was closer to the ratio of leaf C:N (48.8), whereas the litter C:P (257.7) was obviously lower than the ratio of leaf C:P (338.15). We calculated the stoichiometric homeostasis index (1/H) of leaf responses to soil elements and enzyme activities and found that the relationship between leaf C:P and soil C:P was homeostatic (p &lt; 0.05), whereas the remaining indices showed the leaf stoichiometries were strictly homeostatic (p &gt; 0.05). Correlation analysis showed both litter C:P and N:P were positively correlated with leaf and soil C:P, while the stoichiometric ratios of soil elements and enzymes were obviously irrelevant with leaf stoichiometries (p &gt; 0.05). Partial least squares path modeling indicated that litter significantly changed soil element and enzyme characteristics through direct and indirect effects, respectively. However, soil elements and enzymes impacted leaf stoichiometries barely, which was further confirmed by an overall redundancy analysis. In summary, C:N:P stoichiometry within the plant–soil continuum revealed that natural P. tabuliformis is a relatively stable ecosystem in the Loess Plateau, where the element exchanges between plant and soil maintain dynamic balance with forest development. Further studies are needed to capture the critical factors that regulate leaf stoichiometry in the soil system.

Carbon Concentration in Tree Components of Mature Pinus brutia Ten. Forests in the Marmara Transition Zone

Aim of study: This study was carried out to determine the carbon concentration of the tree components (needles, wood, bark, root) and the weighted carbon concentrations of the above-ground and total tree mass. Area of study: Current study was carried out in natural Pinus brutia forests in the Marmara Transition Zone, southern side of Sakarya river. Material and methods: The samplings were made in 10 stands in the mature stage (dbh = 20.0-51.9 cm) that were different in terms of habitat characteristics. Needle, wood, bark, and root samples were taken from three dominant trees in each sample plot. Carbon was analysed in the laboratory in samples of tree components. The data obtained were evaluated by analysis of variance and Duncan multiple comparison test. Main results: Significant differences were determined between carbon concentration of tree components (p&amp;lt;0.001). The lowest carbon concentration (50.25%) was found in root and the highest (54.90%) in the bark. The weighted carbon concentration was calculated as 52.07% for the above-ground and 51.77% for the total tree biomass. Highlights: The results obtained can be used for the calculation of carbon stocks stored in both whole and in different components of trees in Pinus brutia forests.

Factors influencing successful establishment of exotic Pinus radiata seedlings with co-introduced Lactarius deliciosus or local ectomycorrhizal fungal communities.

An introduction of exotic or non-native trees may fail due to a lack of suitable fungal partners. We planted exotic Pinus radiata in Xifeng, Guizhou Southwest China. Strategies to introduce P. radiata seedlings either colonized with an ectomycorrhizal fungus (EcMF), Lactarius deliciosus, or expect them to form familiar/new associations with local EcMF in a new habitat were studied to know how P. radiata could be successfully established over a period of 2.5 years. Plant height and needle nutrient acquisition, the persistence of the co-introduced L. deliciosus, and fungal community composition in rhizosphere soil and root tips were analyzed. In addition, a greenhouse bioassay experiment of local soil to assess the differences in the EcMF community between exotic and native pine seedlings was also conducted. The current results demonstrated that P. radiata could establish in the Xifeng plantation with or without co-introduced L. deliciosus. The co-introduced L. deliciosus might be naturalized with P. radiata in the new area since it has been fruited for 2 years with high relative abundance in mycorrhizosphere soil. L. deliciosus pre-colonization significantly altered the mycorrhizosphere fungal composition and it had a positive correlation with nitrogen acquisition of P. radiata. Host identity had no effect on fungal composition since exotic P. radiata and native P. massoniana recruited similar local fungal communities in early establishment or in plantation. The cosmopolitan species Suillus placidus, with high relative abundance, formed a familiar association with P. radiata. The greenhouse bioassay experiment further showed that Suillus sp. contributed relatively higher total extracellular enzymes by forming ectomycorrhizas with P. radiata and the same type of ectomycorrhiza of P. radiata and P. massoniana showed different enzymatic functions. Our study indicated that exotic P. radiata could be a suitable tree capable to get established successfully in the Xifeng plantation either by interaction with the co-introduced L. deliciosus or with a local EcMF, but we should be cautious about large-scale planting of P. radiata. L. deliciosus persisted in plantation and more attention should be paid to local EcMF community changes induced by the introduced L. deliciosus.

Variability of soil properties with fire severity in pine forests and reforested areas under Mediterranean conditions

Abstract It is well known how fires affect the properties of forest soils depending on its severity. A better understanding of the magnitude of these impacts is essential to setup effective management actions after fire against the losses of soil and biodiversity. However, physical, chemical and biological processes in burnt soils are complex, resulting in a diversity of fire-induced changes, as acknowledged in many literature studies. Moreover, these changes may be even variable between natural forests and reforested areas. This study explores the changes in the most important soil properties with fire severity, from low to high. The main chemical parameters of soils were measured after field sampling in different pine forests (burnt natural stands, reforested areas as well as unburnt sites) of Castilla La Mancha (Central Eastern Spain). In comparison to the unburnt soils, the investigation has shown in the burnt areas: (i) no evident changes in soil pH at all fire severities, except in natural stands burnt at a very high severity (showing an increase of about 10%); (ii) increases in the organic carbon content (by about 70%) of soils burnt at a moderate fire severity under both forest ecosystems, and in reforested areas at very high fire severities (+95%); (iii) small differences in the nitrogen content of soil, except for a significant increase measured in soils burnt at an moderate fire severity under both the natural pine stand and reforested area (about +300%); (iv) a limited variability of the phosphorous content in the soil, with only an increase in soils under natural pine stands burnt at moderate fire severity (by 250%); (v) increases in magnesium and potassium contents in soils burnt at the highest fire severities for both land conditions, and decreases in calcium content in reforested areas burnt at the highest severity. Due to some negative impacts (increase in pH and decrease in organic carbon), the implementation of post-fire management actions at natural pine stands burnt at the highest fire severity should be a priority over reforested areas. Overall, this study did not show a straightforward pattern between soil properties, fire severity and land condition. This means that other parameters (for instance, the hydrological properties of soils) that were not explored in this investigation could have played an important role, and therefore must be taken into consideration when defining post-fire management actions.

Dynamics of ecosystems of fresh subor (pine woods on sandy soils) in the central part of the Volga Upland

The results of our study of the dynamics of fresh subor (B2), a widespread type of forest ecosystems in the central part of the Volga Upland, are presented. The study was carried out on the territory of the Upper Sura section of the Privolzhskaya Forest-Steppe Nature Reserve. The course of the process was studied in the age series identified in homogeneous forest conditions based on the principles of dynamic classification of forest types. As a result of processing the forest inventory data, the average values of forest stand taxation indicators were obtained for each age class. At the same time, analysis of changes in all the components of plantations was carried out. On its basis, the age series was divided into separate periods and phases. Trends in the share of participation of each forest-forming species in the forest stand at different age stages were described by nonlinear equations. The study showed the resulting age series to be a series of transformation of forest communities. Violation of the course of the forest formation process led to a large-scale change of indigenous plantations to derivative ones. After the beginning of the use of clear-cutting fellings, the area occupied by deciduous trees (primarily birch) has been constantly growing. The largescale use of intermediate-use, sanitary and voluntary-selective cuttings resulted in the formation of sparse pine stands. At the same time, transformation of the lower tiers of communities took place. These factors caused deterioration of the conditions for natural pine regeneration (Pinus sylvestris L.). As a result, by now the possibility of forming pine forest stands through natural regeneration is almost completely excluded.

Field Trials to Assess the Growth, Survival, and Stomatal Densities of Five Mexican Pine Species and Their Hybrids under Common Plantation Conditions

Understanding hybridization is important for practical reasons, as the presence of hybrid trees in seed stands can influence the success of natural regeneration and reforestation. Hybridization creates new gene combinations, which can promote or enhance adaptation to new or changing environments. In the present research, we aimed, for the first time, to evaluate and compare the growth and survival of 541 putative hybrid seedlings and 455 seedlings of the pure parental trees of Pinus arizonica, P. durangensis, P. engelmannii, P. leiophylla, and P. teocote, in two reciprocal trials of duration 27 months in the Sierra Madre Occidental (SMO), Durango, Mexico. We also examined the possible correlation between needle stomatal density and seedling growth and survival. The overall analysis of the data showed that the mean height to the apical bud was significantly higher (p = 0.01) in the hybrids than in the pure trees. Considering both trials, the survival rate of P. arizonica (p = 0.002) and P. durangensis (p = 0.01) hybrids was significantly higher than that of the pure trees. The growth parameters were significantly correlated with the mean stomatal density (p &lt; 0.01). Stomatal density and survival at the seed stand level were significantly and positively correlated in the hybrids, but not in the pure trees. In summary, Pinus hybrids generally exhibited the same ability as the pure species (or sometimes a greater ability) to withstand weather conditions, survive, and grow effectively in both growth trials. The systematic use of natural pine hybrids in Mexico could therefore be considered a possible option for sustainable management and as a component of adaptive silviculture.

Radial Growth Responses of Four Southeastern USA Pine Species to Summertime Precipitation Event Types and Intense Rainfall Events

Previous dendroclimatic studies have examined the relationship between total precipitation amounts and tree radial growth in the southeastern USA, yet recent studies indicate that specific precipitation event types and rainfall intensities influence longleaf pine (Pinus palustris Mill.) radial growth unequally. It remains unknown if other pine species respond similarly regarding specific precipitation types and intensities as most dendroclimatic studies have focused on precipitation amounts on monthly-to-annual scales without examining either the event type or intensity nor focusing on daily data. Here, we examine summertime climate–radial growth relationships in the southeastern USA for four native pine species (longleaf, shortleaf, Virginia, pitch) during 1940–2020. We examine and compare each species’ response to precipitation event types and intense rainfall events (IREs) and address if the temporal sensitivity to these events is species specific. Distinct temporal sensitivities exist among species, and there is a consistent association between convective, stationary front, and quasi-stationary precipitation and radial growth. All species except Virginia pine have significant (p &lt; 0.001) associations between IREs and radial growth, even though IREs account for ~49% of summertime rainfall. These results suggest precipitation-type sensitivity to radial growth may have dendroclimatic implications.

Does leaf mass per area (LMA) discriminate natural pine populations of different origins?

Tree provenance trials are believed to be a valuable tool for assessing the adaptive potential of a population to a changing environment and ultimately for predicting the populations that are best adapted to global warming. Here, the phenotypic plasticity of morphometric traits of needles and lateral shoots of pines growing in a provenance plot in central Poland was examined to assess the inter- and intra-population variability. No significant differences were found in the measured and counted morphometric features, i.e., needle length (NL), cumulative needles length (CNL), thickness (ST), volume (SV) and shoot density (SD), number of needles per 5 cm fragment of shoot (NN), dry weight of needles (NDW) and shoot (SDW), thickness of bark (BT) and wood (WT), pith diameter (PD), and needle dry mass per area (LMA) among three pine populations while accounting for their region of origin (inter-population variability). In terms of the above-mentioned features, individual populations differed significantly from each other, except for NN and ST. We also noticed a positive, significant relationship between LMA and ST in all studied populations and based on Euclidean distances of measurable or counted traits, three population groups were identified. We concluded that LMA, which is commonly used to quantify leaf structure, is helpful in differentiating intra-population variability.