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Specimens of Amanita sect. Caesareae, collected in Xieng Khouang and Vientiane provinces in Laos from highland forests dominated by members of Fagaceae and Pinaceae, are studied based on morphological characters and analyses of ITS sequences. Two species, namely A. princepoides and A. chepangianoides, are reported as new, both found in association with Fagaceae, whereas A. pseudoprinceps and A. subhemibapha, recently described from China and A. rubromarginata from Japan, are confirmed from Laos and found in forests with Fagaceae and Pinaceae. The phylogenetic analyses to recognize the Amanita species showed that the golden-brown to greyish orange A. princepoides and the dominantly white A. chepangianoides cluster with A. aporema, A. chepangiana, A. egregia, A. princeps and A. pseudoprinceps. A dichotomous key to identified and likely occurring Amanita species in Laos within sect. Caesareae is also provided. [ABSTRACT FROM AUTHOR]

Proper management of woody ecosystems is fundamental for human livelihoods and biodiversity conservation. Strip cutting or selective harvesting are proposed as sustainable alternatives to clear-cut logging. However, their impacts are not fully understood, especially when we consider the harvesting intensity levels and the invasibility of an ecosystem by nonnative tree species. In this study we analyzed the impacts of different harvesting intensity levels on the establishment after 2 years of nonnative and native tree species. We conducted this study in a mixed forest dominated by Nothofagus antarctica, where we applied four strip harvesting levels: 0% (control), 30%, 50% and 70% percentage of vegetation removal in eight plots (1417.5 m2 each plot) Inside those plots, we had a total of 24 subplots (3 sites × 8 plots) were we sowed seeds of a total of six tree species, that can form dominant stands in the studied region. Three species were nonnative invasives in the region (Pinus ponderosa, Pinus contorta and Pseudotsuga mensiezii), and the other three were native species (Austrocedrus chilensis, Nothofagus obliqua and Araucaria araucana). We found that in the high harvesting intensity treatments, the establishment after 2 years of all nonnative trees and only one native species (A. araucana) was increased in spite of the ecological and structural differences (i.e., productivity levels) between sites. Invasion by nonnative tree species can have important negative economic and ecological consequences on the logged ecosystems, so their removal may be required to keep them away from colonizing and dominating the logged areas, especially at high harvesting intensities. [ABSTRACT FROM AUTHOR]

The role of the roots and root systems of Pinus sylvestris L. in the formation of secondary pine forests in the cuttings of the Kola North was studied. It has been established that in pine seedlings in disturbed areas, root and shoot systems are formed quite quickly. Already in age class I, characteristic morphological signs of root systems appear and the feeding areas of trees begin to overlap each other. The bulk of the roots (80–85%) is concentrated in the upper 20-cm soil layer. A linear relationship between the taxation indicators of trees and the mass of root systems has been revealed. The conducted studies have shown that the formation of forest communities of Scots pine in the cuttings of the Kola North and their stability and productivity are directly dependent on the degree of development of individual roots and root systems as a whole. [ABSTRACT FROM AUTHOR]

The nurse effect is a positive interaction in which a nurse plant improves the abiotic environment for another species (beneficiary plant) and facilitates its establishment. The evergreen shrub Vaccinium vitis-idaea (a beneficiary plant) grows mainly under the dwarf shrub Pinus pumila (a nurse plant) in the alpine regions of central Japan. However, whether V. vitis-idaea shrubs under various P. pumila shrubs spread through clonal growth and/or seeds remains unclear. We investigated the clonal structure of V. vitis-idaea under the nurse plant P. pumila in Japanese alpine regions. MIG-seq analysis was conducted to clarify the clonal diversity of V. vitis-idaea in isolated and patchy P. pumila plots on a ridge (PATs), and in a plot covered by dense P. pumila on a slope adjacent to the ridge (MAT) on Mt. Norikura, Japan. We detected 28 multilocus genotypes in 319 ramets of V. vitis-idaea across 11 PATs and MAT. Three genets expanded to more than 10 m in the MAT. Some genets were shared among neighboring PATs or among PATs and MAT. These findings suggest that the clonal growth of V. vitis-idaea plays an important role in the sustainability of populations. The clonal diversity of V. vitis-idaea was positively related with the spatial size of PATs and was higher in MAT than in PATs at a small scale. Therefore, the spatial spread of the nurse plant P. pumila might facilitate the nurse effect on the genetic diversity of beneficiary plants, leading to the sustainability of beneficiary populations. [ABSTRACT FROM AUTHOR]

Promoting nature-based carbon sinks may contribute to minimise global warming. Different forest types may have different carbon sink capacity. Many areas of central Spain are covered by coexisting patches of monospecific plantations of Pinus halepensis, established since the 1960's, and native Quercus forest coppiced up to the 1960´s. We aimed to compare the carbon stock between both types of forests, considering both above and belowground compartments. In each plot, we measured the dimensions of every adult tree, the shrub cover, and we collected samples of litter and soil. The carbon pool of trees and shrubs was calculated using allometric equations, and for roots, litter, and soil, using the carbon content analysed in a laboratory or obtained from the literature. Carbon pools were analysed separately for three independent variables: plot type (Quercus/Pinus), tree basal area and slope. Overall, Quercus forests stored more carbon than Pinus plantations, thanks to a larger carbon stock in roots and shrubs in the former, which compensated for the larger aboveground carbon stock in tree biomass of Pinus plots. The carbon stock increased with basal area in all compartments except the soil. The carbon allocation pattern across compartments greatly varied between the two forest types, Pinus plots storing more than half (55%) of its carbon in the aboveground biomass of trees, while Quercus storing more carbon belowground (60%) in roots and soil. Given that belowground carbon stock is more resistant against disturbances, we conclude that native Quercus forests are more suitable for a long-term carbon storage. [ABSTRACT FROM AUTHOR]

The effect of an inoculum composed of Amanita stranella and Suillus decipiens was evaluated on morphological features and total phenolic compounds in seedlings of Pinus pseudostrobus var. coatepecensis – a narrow endemic Mexican variety. The treatments were used: (1) A. stranella; (2) S. decipiens; (3) combined inoculum and (4) control, using a completely randomized design with 12 seedlings per treatment. The morphotype descriptions of both fungi significantly facilitate their identification in the field. The results showed significant differences in plant growth among the treatment groups. Seedlings treated with the combined treatment exhibited remarkable increases in height, surpassing the A. stranella, S. decipiens treatments, and the control group by 21.81%, 28.83%, and 59%, respectively. Moreover, the root collar diameter in the combined treatment group measured 2.53 cm, contrasting with the control group, 1.05 cm. Additionally, the shoot height/root length ratio and Dickson's index were both close to 1 in the combined treatment, suggesting a well-developed root system in relation to the above-ground part of the plant. The percentage of ectomycorrhizal root colonization showed no significant differences among the inoculated treatments. Furthermore, the combined treatment significantly increased the total phenolic content in plants (39.2 mg GAE g− 1). Therefore, the combined inoculation of P. pseudostrobus var. coatepecensis seedlings with A. stranella and S. decipiens is recommended during the nursery stage for reforestation practices. [ABSTRACT FROM AUTHOR]

Species in the genus Picea are well-suited for afforestation on high altitudes and latitudes, but are fairly intolerant to high temperatures. In this study, Picea pungens, Picea abies, and Picea omorika were subjected to 45 °C, 40 °C, 35 °C, and ambient temperature (CK) for 6 h, and then allowed to recover for 28 d. Changes in phenotype, relative water content (RWC), and maximal photochemical efficiency (Fv/Fm) of photosystem II (PS II) were observed to ascertain their thermal tolerance. Overall, all three species were negatively affected by exposure to 45 °C, but P. pungens exhibited full recovery, with the highest RWC, while P. omorika exhibited partial recovery, and P. abies showed minimal recovery. The PS II of all three species were damaged after 45 °C treatment, but that of P. pungens exhibited the most dramatic recovery, with Fv/Fm recovering from 0 to 0.26. In conclusion, P. pungens was found to exhibit the greatest thermal tolerance, followed by P. omorika and P. abies. Thus, thermal tolerance should be considered as a tool for species selection for future reforestation endeavor in the face of climate change that is expected to bring high summer temperature events. [ABSTRACT FROM AUTHOR]

As a component of the biogeochemical cycle, litterfall contributes carbon and nutrients to forest ecosystems by transferring organic material to mineral soil. Litterfall therefore serves as an important indicator for soil fertility and ecosystem health. This study aimed to determine the impact of different levels of thinning (light, moderate, and heavy) on litterfall quantity (needles, branches, bark, cones, and miscellaneous parts) and on the amount of carbon and nutrients entering the ecosystem in black pine afforestation areas. Three levels of low thinning, namely light, moderate, and heavy thinning (15%, 25%, and 35% of breast height area, respectively), were applied as treatments. Additionally, a control plot was included in the experiment. Litterfall samples were collected four times per year (once per season) from 12 treatment plots for three years. In the laboratory, dry weight measurements and analyses of carbon and macro–micro nutrient elements (N, P, K, Ca, Mg, S, Na, Fe, Cu, Zn, and Mn) were performed on litterfall samples taken from the field. Differences between treatments in terms of litterfall and the amount of carbon and nutrient elements entering the ecosystem were evaluated through variance analysis and the Duncan test. According to the findings, the quantity of litterfall input into the forest floor was highest in the control treatment, at 6,543 kg ha−1 year−1 and lowest in the heavy treatment, at 4,378 kg ha−1 year−1, showing a significant variation in litterfall quantity. The input of C to the soil ranged between 2,233 kg ha−1 year−1 and 3,347 kg ha−1 year−1 depending on thinning treatment. Although thinning treatment reduced C input to the soil, there was no significant difference among treatments. This also applied to nutrient elements such as N, P, K, Mg, and S. Needles constituted the majority of litterfall components (60%) and had the highest C density among all components, at 51.2%. The weighted carbon ratio for litterfall was calculated at 50.8%. Considering carbon-focused planning, performing moderate thinning interventions in the study area or similar pine-afforested areas may be a suitable option for maintaining the sustainability and health of the forest. [ABSTRACT FROM AUTHOR]

The composition of the vascular flora in Punta Arenas city, found in the city's public spaces, was studied. The species were identified and recorded in a database, which was supplemented with information on taxonomic classification, growth habit, Raunkiaer's life form, origin status (native or exotic), and original continent-level distribution. These data were compared with studies conducted in five other cities in central Chile, together with an analysis of compositional similarity with these cities, by using the additive complement of Simpson's index (1– βsim). In Punta Arenas, 119 species were identified, showing a higher proportion of Gymnosperms compared to central Chilean cities. The most represented families were Asteraceae (16 species), Fabaceae (14), Rosaceae (14), Poaceae (12), and Pinaceae (10), which together accounted for 55% of the floristic richness. The compositional similarity between Punta Arenas and the other central Chilean cities ranged from 0.187 to 0.315, showing lower similarity than expected by chance (Montecarlo randomization test; P < 0.05). The primary origin distribution of Punta Arenas' vascular flora was European, unlike central Chilean cities where it was Asian. Finally, the proportion of exotic species (91.6%) and the number of exotic species per native species (16 exotics/native) were the highest documented for cities in Chile and higher than in other 114 cities worldwide. These results indicate that Punta Arenas' urban flora differs from the flora in central Chilean cities, not only in taxonomic composition but also in growth habit, biogeographical origin, and high level of exoticism. These differences are likely due to the city's territorial isolation and extreme southern location (53°S), leading to a unique urban flora configuration. [ABSTRACT FROM AUTHOR]

It can provide a basis for decision making for the conservation and sustainable use of forest ecosystems in mountains to understand the stoichiometric properties and nutrient allocation strategies of major tree species. However, the plant nutrient allocation strategies under different environmental gradients in forest systems of arid and semi-arid mountains are not fully understand. Therefore, three typical regions in the Qilian Mountains on the eastern edge of the Qinghai-Tibet Plateau were selected based on precipitation and temperature gradients, and the stoichiometric characteristics and nutrient allocation strategies of Qinghai spruce (Picea crassifolia) of the dominant tree species under different environmental gradients were investigated. The results showed that (1) the stoichiometric characteristics of plant tissues were different in the three regions. (2) The importance of each tissue in the plant nutrient allocation varied in different regions, showing that the plant roots are more important in the warm-wet region, while the plant leaves, branches and trunks are more important in the transition and hot-dry regions. (3) The influencing factors affecting plant nutrient allocation strategies were inconsistent across regions, which showed that plant nutrient allocation strategies in the warm-wet and transition region were mainly influenced by soil factors, while they were more influenced by climatic factors in the hot-dry region. The patterns of plant nutrient allocation strategies and drivers under different environmental gradients could help us better understand the ecological adaptation mechanism and physiological adjustment mechanism of forest ecosystem in mountains. [ABSTRACT FROM AUTHOR]

The modern typological structure of vegetation inhabiting the southern Kuril Islands has been identified on the basis of computed Bravais correlation coefficients. This structure is represented by eight pleiades: fir forests with Abies sachalinensis; spruce forests with Picea ajanensis; Sasa senanensis thickets (Shikotan Island); elm–maple forests with Acer ukurunduense and Acer mayrii (Kunashir Island); maple–oak forests with Acer mayrii and Quercus crispula (Iturup Island); Juniperus sargentii thickets (Shikotan Island) and communities with Pinus pumila (Iturup and Kunashir Islands); and alder–birch phytocoenoses, reed–tall-grass and coastal meadows, and ruderal vegetation. The species diversity of plants is determined by local species of East Asian origin. The amphipacific group manifested along the coastline demonstrates the affinity of local species and the North American flora. The proportion of foreign species increases on disturbed sites. Indigenous phytocoenoses are represented by fir and spruce forests, as well as Pinus pumila and Juniperussargentii thickets in the mountains and on the rocks. Under the impact of unfavorable factors, indigenous groups are replaced by birch forests with Betula ermanii and secondary meadows, including ruderal–forb–gramineous coenoses; felling and fire sites are overgrowing with bamboo thickets with Sasa senanensis. Preliminary estimates indicate that the share of disturbed lands on Shikotan reaches 40%, including 30% disturbed by anthropogenic impacts and 10% due to natural factors. On Kunashir, proportions of these lands amount to 16 and 17%, respectively, and, on Iturup, 23 and 16%. It is shown that Sasa senanensis thickets, despite their secondary nature, play a key role in preventing the further degradation of natural complexes, soil erosion, and exogenous geological processes. [ABSTRACT FROM AUTHOR]

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The high-resolution pollen record retrieved from dated sediments of the Khanka Depression has made it possible for the first time to reconstruct evolution of vegetation in the south of the Russian Far East that occurred during one of the coldest phase of MIS 2 – the Younger Dryas. The results of the spore-pollen analysis have shown that worsening of climate conditions between 18 200 and 15 500 cal yr BP that occurred after the first, slight warming during MIS 2, caused boreal flora plants, dominating in the south of Russian Far East, to spread again in the drier and colder climate comparable to the Gydan Stage of the Sartan Glaciation. Their distribution areas in the cold climate that differed significantly from the modern ones again started to shift to the south due to increasing cooling. The spruce and small-leaved forests, sparse larch and dwarf birch, alder and dwarf pine forests, and also sphagnum bogs dominated in the ecosystems of the region. [ABSTRACT FROM AUTHOR]

Given increasing forest disturbances, novel solutions are needed to rapidly recover ecosystem services such as carbon storage, while bolstering climate change adaptation. Reforestation with single-species mixed-provenance plantings is an emerging strategy that may enhance stand productivity and disturbance resistance, while assisted gene flow is a potentially powerful tool for matching seed-source with future planting-site climate. We investigated the potential of mixed-provenance plantings and assisted gene flow for maximizing early growth using a historical dataset for knobcone-Monterey pine (Pinus x attenuradiata), a fire-resilient hybrid developed for low-elevation sites in California, USA. We examined (1) 9-year individual-tree relative growth rate (RGR) in response to neighborhood seed-parent provenance diversity at two test sites and (2) 3-year RGR and survival as functions of parent seed-source climate at 4 test sites. We found 9-year RGR varied with seed provenance diversity, with 3 of 5 provenances showing a positive RGR-diversity relationship. Parent seed-source climate affected 3-year RGR but not survival. Closer climate matches in terms of precipitation as snow (PAS) showed fastest growth. Our results suggest careful selection and arrangement of genetically diverse stock may improve carbon sequestration and initial planting success in a hybrid conifer, with implications for reforestation under climate change and reburn risk. [ABSTRACT FROM AUTHOR]

Phytoremediation using fast-growing woody plants assisted by plant growth-promoting bacteria (PGPB) on cadmium (Cd)–contaminated sites is considered a promising technique; however, its remediation efficiency is still affected by multiple factors. In this study, the mining areas' soil conditions were simulated with different Cd addition levels (0, 3, 6, 9 mg kg−1) in order to investigate the response strategy to Cd stress of fast-growing economic tree species, slash pine (Pinus elliottii), and the effects of inoculation with the PGPB strain Herbaspirillum sp. YTG72 on the physiological activity and Cd accumulation of plants. The main results showed that there were significant (p < 0.05) increases in contents of chlorophyll and nutrient elements (P, K, Ca, and Mg) at low Cd addition level (3 mg kg−1) compared to non-Cd addition treatment. When the additive amount of Cd increased, the growth of plants was severely inhibited and the content of proline was increased, as well as Cd in plants. Besides, the ratios of K:P, Ca:P, and Mg:P in plants were negatively correlated with the contents of Cd in plants and soils. Inoculation of P. elliottii with the PGPB strain Herbaspirillum sp. YTG72 improved the physiological functions of the plants under Cd stress and activated the antioxidant system, reduced the accumulation of proline, and decreased the ratios of K:P, Ca:P, and Mg:P in plant. More importantly, planting P. elliottii in Cd-contaminated soil could significantly (p < 0.05) reduce the Cd content in the rhizosphere soil, and furthermore, inoculation treatment could promote the reduction of soil Cd content and increased the accumulation of Cd by root. The results of the present study emphasized the Cd response mechanism of P. elliottii based on multifaceted regulation, as well as the feasibility of strain Herbaspirillum sp. YTG72 assisted P. elliottii for the remediation on Cd-contaminated sites. [ABSTRACT FROM AUTHOR]

Direct organogenesis is an important technique for plant rapid propagation, which is mainly controlled by the balance of auxin and cytokinin. Pinus massoniana (Lamb.) is a perennial tree species with high application value. Previous studies have shown that direct organ regeneration of young P. massoniana is feasible. However, there are few reports on direct organogenesis of adult P. massoniana. This research studied the effects of apical shoot bud disinfection, plant growth regulators of axillary bud induction, and adventitious root induction of adult P. massoniana. The results showed that the survival rate could reach 50% after removing the outer coat scales and soaking in 500.0 mg L−1 carbendazim solution for 10 min, 75% alcohol for 30 s, and 2.0% NaClO with one drop of Tween for 25 min. The addition of 0.2% plant preservative mixture (PPM) to the medium effectively inhibited contamination of endogenous bacteria, and the survival rate was 90%. The suitable medium for axillary bud induction was Murashige and Skoog (MS) basal medium with 6-benzyl aminopurine (6-BA, 2.0 mg L−1) and indolebutyric acid (IBA, 0.1 mg L−1), and the induction rate reached 15%. A single apical shoot bud induced up to seven axillary buds, and the axillary buds grew vigorously. In addition, 6-BA (2.0 mg L−1) was suitable for needle bundle axillary bud induction. Quarter Douglas-fir cotyledon revised medium (DCR; Gupta and Durzan 1985) with naphthaleneacetic acid (NAA, 0.5 mg L−1) and IBA (0.1 mg L−1) was the most suitable for adventitious root induction. This study preliminarily constructed a regeneration system for direct organogenesis of adult P. massoniana, which was expected to provide key technical support for vegetative propagation of excellent breeding materials for adult P. massoniana. [ABSTRACT FROM AUTHOR]

Data on the status of two natural populations of the rare, endemic medicinal species Alangium platanifolium known from the Russian Federation is provided in this article. Information about one of them is reported for the first time. Geobotanical descriptions of the phytocenoses are presented. In southern Primorskii krai, A. platanifolium has been noted to grow in the shrub layer of coniferous/broad-leaved forest with Pinus koraiensis and Abies holophylla. It has also been found that the area of the population discovered 20 years ago has expanded tenfold and now amounts to 10 ha. The new locality of A. platanifolium covers an area of 0.25 ha. The total number of A. platanifolium is more than 700 of various-age plants. The data obtained extends the current knowledge of the distribution and life state of A. platanifolium and indicates the fact of the growth of subtropical elements in phytocenoses of the Russian Federation. [ABSTRACT FROM AUTHOR]

The issues of the environmental evolution of the western sector of the Khanka valley and the evolution of Lake Khanka are considered for the maxima of the last glaciation and Late Pleistocene lacustrine transgression. The lithological indicators and results of diatom analysis of lacustrine sediments of Lake Khanka indicate two sedimentation conditions over the period of 24.0–19.0 cal ka BP: an oligotrophic–mesotrophic moderately swampy shallow reservoir with an unstable level and a relatively deep lake. The maximum of the transgression occurred at ~19.6 cal ka BP, when the lake level was 1.5–2.0 m higher than at present for the first time. Four phases of the vegetation evolution in the western sector of the Khanka valley are distinguished: I, birch–larch mari with alder and frigid shrubs (23.8–22.8 cal ka BP); II, dark coniferous taiga with dwarf pine and a small amount of broad-leaved trees (22.8–20.6 cal ka BP); III, spruce forests with dwarf pine, fir, larch, and rare oak (20.6–20.1 cal ka BP); and IV, light birch forests and larch mari with frigid shrubs (20.1–19.0 cal ka BP). Two cooling phases are registered at the Khanka valley (~24.0 cal ka BP (cooling maximum) and 20.6 cal ka BP) and one warming phase (∼22.8 cal ka BP), which are correlated with the detailed global Greenland glacier records. The driest periods occurred at 21.7–21.2 cal ka BP. The quantitative characteristics of climate events are reconstructed from modern plant analogs. [ABSTRACT FROM AUTHOR]

Urban trees' biomonitoring of pollutants such as polycyclic aromatic hydrocarbons (PAHs) yields pertinent and useful data for air pollution management. The aim of this study was to biomonitor PAHs in pine (Pinus eldarica Medw.) trees in the city of Isfahan and identify their sources. In total, 34 samples of outer bark of the trees were collected and their contents of 16 EPA PAHs were analyzed. With a median value of 136.3 ng/g, the total PAH contents in tree barks varied from 53.4 to 705.2 ng/g. The average values of the diagnostic ratios for Ant/(Ant + Phe), Flu/(Flu + Py), BaA/(BaA + Chr) and IP/(IP + BP) were 0.19, 0.49, 0.45 and 0.49, respectively, revealing the PAHs majority source of pyrogenic. Meanwhile, principal component analysis showed two major types of PAHs sources including pyrogenic (fossil fuel combustion and industrial activities) and petrogenic (uncombusted) sources. The average ratio An/(An + Phe) and Flu/(Flu + Py) in bark samples was close to their relevant ratios in ambient air which demonstrated the potential use of this approach for biomonitoring of PAHs. [ABSTRACT FROM AUTHOR]

Background and aims: Coordination between leaf and root traits is crucial to plant performance and ecosystem functioning, but how leaves and roots coordinate in ectomycorrhizal (ECM)-dominated alpine forests remains unclear. Therefore, the covariation patterns of leaf and root traits of ECM-dominated alpine conifers and the environmental drivers were examined. Methods: Five pairs of key leaf (i.e., leaf thickness [LT], specific leaf area [SLA], leaf tissue density [LTD], leaf N and P concentrations) and fine-root traits (i.e., root diameter [RD], specific root length [SRL], root tissue density [RTD], root N and P concentrations) were measured across 49 alpine coniferous populations (including 8 coniferous species) on the Tibetan Plateau. Results: Root traits including RTD, root N and P concentrations and leaf traits such as LT, SLA, LTD, leaf N and P concentrations were correlated. The root-leaf relationships represent a tradeoff between resource conservation and fast plant growth, i.e., plant economic spectrum. RD and SRL were independent from the plant economic spectrum. Temperature drove variations in the leaf traits, RTD, root N and P concentrations, and conifers under low temperature had denser leaves and roots (i.e., larger LT, LTD, RTD) and lower nutrient contents. Precipitation primarily controlled variations in RD and SRL, and roots became thinner with decreasing precipitation. Conclusion: Our study demonstrates divergent roles of temperature and precipitation in driving the coordination of leaf and root economic traits in the ECM-dominated alpine coniferous ecosystems. This is insightful for a comprehensive understanding of the adaptation and responses of alpine forests to climate change. [ABSTRACT FROM AUTHOR]

Background and Aims Pinus massoniana: Lamb. is an important conifer forestry species in south China, but soil fertility has declined over time in monoculture plantations. Knowledge about how P. massoniana uses phosphorus (P) by distributing it among five biochemical fractions and how intercropping with broadleaf Castanopsis hystrix alters that pattern may inform long-term plantation management. Methods: We studied a single P. massoniana plantation that was split in half into a monoculture and a P. massoniana / C. hystrix intercropped plantation 25 years after establishment. We measured photosynthesis and leaf concentrations of total P, P allocated to five chemical fractions and total nitrogen (N). We also measured soil N concentrations. Results: Intercropping C. hystrix with 25-year-old P. massoniana for a further 34 years had no significant impact on P. massoniana total stem volume, although intercropped P. massoniana trees were 5 m taller. Intercropping with C. hystrix increased timber biomass due to the additional C. hystrix stems. Growth of C. hystrix was likely more limited by P than that of P. massoniana in both plantations. Total P concentration and its allocation among fractions declined with increasing leaf age, but differed in the two species. Leaf P-resorption efficiency in intercropped P. massoniana was 79%, which was about 15% greater than that in P. massoniana monoculture and in the intercropped C. hystrix. The greater P-resorption efficiency in intercropped P. massoniana than in monoculture was due to greater mobilization of P from all fractions, except phospholipids. Bulk soil N concentration was 50% greater in the intercropped plantation than in monoculture. Conclusion: Adding C. hystrix to an P. massoniana plantation was effective at increasing wood yield without compromising productivity of P. massoniana. [ABSTRACT FROM AUTHOR]

The study of modern pollen, and vegetation can improve the accuracy of paleoenvironmental reconstruction based on fossil pollen data. A total of 188 pollen surface samples were collected from Southern Xinjiang (34°00′–43°00′N, 74°00′–94°00′E) in China, with an elevation range of 888–1530 m. Surface pollen and vegetation were studied in the northern region of the Kunlun Mountains and the southern region of the Tianshan Mountains. The results showed that the surface pollen assemblages on the southern slope of the Tianshan Mountains (3530–1124 m) were divided into three pollen zones, namely, montane steppe, montane desert steppe, and montane desert. These zones were dominated by Artemisia, Chenopodiaceae, and Ephedra pollen. The surface pollen assemblages in the eastern Pamir Plateau (4530–1287 m) could be divided into alpine meadow, montane desert steppe, and montane desert zones, which were predominantly characterized by Artemisia, Chenopodiaceae, and Asteraceae pollen. However, the Southern Tarim Basin (3548–888 m) comprised montane desert steppe and montane desert zones, which was dominated by Artemisia and Chenopodiaceae pollen. The geographic distribution of the surface pollen sites obtained using ArcGIS, the R-value, and Pearson correlation analyses indicated that the over-represented Picea and Pinus pollen were of external origin and were transported by wind, water (rivers), and ice (glacier movement). Over-representation of Ephedra and Nitraria pollen was mainly distributed in the montane desert and desert steppe zones, respectively. Pollen from Chenopodiaceae and Artemisia were over-represented and broadly distributed across Southern Xinjiang. Juglans pollen was concentrated in areas with walnut trees, strongly indicating the presence of local parent plants. According to the Hybrid Single-particle Lagrangian Integrated Trajectory model, more Pinus pollen was transported to the Pamir region by external airflows during spring and summer, resulting in its higher surface pollen content. Research elucidating the relationship between modern pollen and vegetation in southern Xinjiang could provide data describing the surface palynological database of Xinjiang for use in large-scale paleoenvironmental reconstructions. [ABSTRACT FROM AUTHOR]

Global climate change is expected to increase the frequency and intensity of extreme droughts. Researching tree growth responses to drought helps assess the potential of forest adaptation and ecological stability under changing climate conditions. Here, we investigated tree growth resilience components (resistance, recovery, and resilience) to extreme drought events of two mainly distributed species, Pinus tabulaeformis and Picea wilsonii, on the Gannan Plateau, the Eastern Tibetan Plateau. Tree-ring width data from 510 trees at 20 plots along the elevation gradients were employed to analyze the tree resilience components at the individual tree level. The results showed that P. tabulaeformis had a lower growth resistance and a higher recovery capacity to drought than P. wilsonii, which might be related to the different strategies for combating drought of the two species. In addition, the tree growth response of P. tabulaeformis to drought changed significantly along the elevation gradient due to its higher drought sensitivity than that of P. wilsonii. Overall, the long-term correlation between tree growth and drought index, tree size, and soil water content had implications for tree growth resistance, recovery, and resilience. Given the observed differences in tree growth resistance to drought among different species and environmental conditions, a well-thought-out and tailored strategy would better support forest management on the Gannan Plateau. [ABSTRACT FROM AUTHOR]

Purpose: Forest management practices, such as thinning, can significantly change surface soil properties, understory plant composition, and microclimate. Nevertheless, there remains a dearth of knowledge concerning the influence of forest thinning on soil temperature (Ts) and its connection to environmental factors in open-field. Our study aims to quantify the response of surface Ts (10 cm depth) to different thinning treatments, and to investigate the associations between Ts and various meteorological factors throughout the entire plant growing season. Materials and methods: We established 12 25 m × 25 m plots from Larix principis-rupprechtii plantations receiving four different thinning treatments (i.e., no thinning, NT; low thinning: 15% removal of trees, LT; moderate thinning: 35% removal of trees, MT; heavy thinning: 50% removal of trees, HT). These plots were established on Taiyue Mountain in North China, and the microclimate data were collected 2 years after their establishment in 2012. We obtained continuous (30 min/time) Ts data of 10 cm depth for 1 year, from April 2017 to March 2018. Additionally, other meteorological data including total solar radiation (TSR), air temperature (Ta), relative humidity (RH), air pressure (AP), precipitation, vapor pressure deficit (VPD), and wind speed (WS) were simultaneously recoded by an automatic weather station located in the open area (OA) within the forest, which is completely devoid of vegetation. Results and discussion: Ts in the MT (6.18 °C) exhibited a significantly higher value compared to other treatments in the growing season. Ts under forest cover displayed higher temperatures in the winter and lower temperatures in the growing season compared to the OA. The structural equation model (SEM) indicated that Ta exerted a positive influence as the primary environmental factor affecting Ts. In contrast, VPD exhibited a negative direct effect on Ts during the growing season, while manifesting a positive direct effect throughout the non-growing season. The direct effect of TSR on Ts was negative, and TSR indirectly influenced Ts through its direct effects on VPD and Ta. However, the overall effect of TSR on Ts was found to be positive. Nevertheless, WS generally affected Ts indirectly. Notably, the path coefficients, both direct and indirect, of each meteorological factor on MT treatment were slightly smaller compared to other treatments. Conclusion: Forest thinning of larch plantations influences the dynamics of Ts significantly, with MT leading to warmer soil conditions. Moreover, the structural composition of the plant community plays a crucial role in buffering the fluctuations in understory Ts induced by climatic changes. Our results offer valuable insights into the impacts of forest thinning on Ts and provide important guidelines for future management practices. [ABSTRACT FROM AUTHOR]

Native grasslands in the Pampas of South America are increasingly being replaced by Eucalyptus and Pinus stands. The short rotation regimes used for the stands require high nutrient levels, with litterfall being a major source of nutrient return. To model the litterfall production using climatic variables and assess the nutrient return in 14-year-old Eucalyptusgrandis and Pinustaeda stands, we measured litter production over 2 years, using conical litter traps, and monitored climatic variables. Mean temperature, accumulated precipitation, and mean maximum vapor pressure deficit at the seasonal level influenced litterfall production by E.grandis; seasonal accumulated precipitation and mean maximum temperature affected litterfall by P.taeda. The regression tree modeling based on these climatic variables had great accuracy and predictive power for E.grandis (N = 33; MAE (mean absolute error) = 0.65; RMSE (root mean square error) = 0.91; R2 = 0.71) and P.taeda (N = 108; MAE = 1.50; RMSE = 1.59; R2 = 0.72). The nutrient return followed a similar pattern to litterfall deposition, as well as the order of importance of macronutrients (E.grandis: Ca > N > K > Mg > P; P.taeda: N > Ca > K > Mg > P) and micronutrients (E.grandis and P.taeda: Mn > Fe > Zn > Cu) in both species. This study constitutes a first approximation of factors that affect litterfall and nutrient return in these systems. [ABSTRACT FROM AUTHOR]

In our previous screening of the transcriptome of the causal agent of the devastating pine wilt disease, pine wood nematode (PWN, Bursaphelenchus xylophilus), after treatment with the nematicide fomepizole, Surfeit locus gene sft-4, which encodes a regulatory factor, was found to be downregulated. In situ hybridization results showed that the sft-4 was continuously expressed from egg to adult and was especially high in the reproductive system. Here in a study of the effect of RNA interference (RNAi) of sft-4 and recombinant SFT-4 on PWN activity, treatment with sft-4 dsRNA inhibited feeding, reproduction, oviposition and egg hatching of PWN with the greatest inhibition on reproduction and oviposition, whereas recombinant SFT-4 had the opposite effect. In addition, RNAi of sft-4 changed the female–male ratio and lifespan of PWN. In bioassays of PWNs, with RNAi of sft-4 on seedlings and 2-year-old Pinus thunbergii trees, none of the treated plants developed symptoms during the monitoring period, indicating that virulence of PWNs was either significantly weakened. These results indicate that the influence of sft-4 on PWN pathogenicity may be mainly through regulating reproductive function of PWN and its lifespan. [ABSTRACT FROM AUTHOR]

Shrubs are key components of temperate and boreal ecosystems. Field experiments performed along environmental gradients are useful to study how these species may cope with new climatic conditions. We analyzed the effects of habitat, elevation, and canopy on the performance of the bilberry Vaccinium myrtillus, a key resource for numerous species in boreal and temperate regions of Eurasia. We estimated bilberry dry mass and measured vegetative (ramet height, stem diameter, and shoot production) and reproductive (fruit and seed production) performance of bilberry shrubs in thirty plots located at six study sites established in coniferous forests and subalpine meadows along a 600-m elevation gradient in Tatra National Park, Poland. Although we detected more ramets per plot in the meadows, bilberry dry mass was larger inside the forest, where ramets were heavier and taller and produced more annual shoots. A higher proportion of ramets produced fruits in the meadows, where we additionally found a higher proportion of mature seeds per bilberry fruit. When only plots located inside the forest were considered, we detected a negative relation between elevation and bilberry ramet dry mass. Canopy cover affected the number of ramets and the dry bilberry biomass per plot differently depending on the elevation, demonstrating interactive effects of these two variables in bilberry vegetative performance. Fruit production inside the forest was negatively affected by both elevation and canopy cover, while interactive effects of these two variables determined seed development. Bilberry management actions must consider habitat heterogeneity even at small spatial scales and possible interactive effects of environmental variables such as those analyzed in this study. [ABSTRACT FROM AUTHOR]

Carbon (C) sequestrated in the boreal forest ecosystems plays an important role in climate regulation. This study's objectives were to quantify the differences in the components of the forest C cycle along a 1000 km latitudinal gradient within the boreal region and between dominant coniferous species in Fennoscandia. The study included seven xeric–sub-xeric and eight mesic–herb-rich heath forests dominated by Scots pine and Norway spruce, respectively. The total site carbon stock (CS) ranged from 81 to 260 Mg ha−1. The largest ecosystem component CSs were tree stems, mineral soil, and humus layer, representing 30 ± 2%, 28 ± 2%, and 13 ± 1% of total CS, respectively. On average, the spruce sites had 40% more C than the pine sites, and CS stored in most compartments was higher on spruce than on pine sites. As exceptions, understorey vegetation and litter layer had a larger CS on pine than on spruce sites. The northern sites had an average of 58% less C than the southern sites. Humus layer CS was the only compartment showing no latitudinal trends. Northern sites had a significantly larger fine and small root CS and understorey CS than southern sites. Most CS compartments were significantly correlated with litterfall C transfer components. Dissolved organic carbon (DOC) flux in throughfall was positively correlated with the aboveground tree compartment CS. Our study revealed patterns of C distribution in major boreal forest ecosystems along latitudinal and fertility gradients, which may serve as a reference for Earth system models and in the evaluation of their projections. [ABSTRACT FROM AUTHOR]

This study examines 10 different taxa within the genus Abies identified in the circum-Mediterranean area: A. alba, A. borisii-regis, A. cephalonica, A. cilicica, A. nebrodensis, A. nordmanniana subsp. equi-trojani, A. nordmanniana subsp. nordmanniana, A. numidica, A. pinsapo var. marocana and A. pinsapo var. pinsapo. We assess the potential distribution of these species in the Mediterranean Basin, most of Central-Northern Europe and Asia Minor through analysis of 8 bioclimatic variables. First, the potential distribution (suitability area) was calculated with Biomod2 package for R using 10 algorithms. Models were ensembled for the present period and then projected into two climate change scenarios (an intermediate and the most extreme) within two time slices (2041–2060 and 2081–2100) and two Global Circulation Models (GCMs). The analysis showed an increase in total suitable area under both forecasted scenarios. Abies spp. appeared to be resilient against climate change, showing a latitudinal and longitudinal migration trend in response to the loss of current habitats. A proposal of assisted migration (managed relocation) is suggested as an interesting alternative to guarantee the preservation of the most endangered species by promoting the establishment of new populations outside of their historical distribution area. [ABSTRACT FROM AUTHOR]

Carbohydrate and nitrogen storage in seedlings can improve field growth and survival. However, carbohydrate and nitrogen reserves may compete. For instance, carbohydrate reserves can be accumulated due to sink limitation on growth triggered by nutrient deficiency. Few studies have addressed the effects of nutrient supply on carbohydrate and nutrient storage and subsequent field performance of Quercus and Pinus species with different shoot growth strategies at the early growing stage. We exposed seedlings of Pinus tabuliformis Carr and Quercus mongolica Fisch to three exponential fertilizer treatments (10, 50, 100 mg N) in the nursery for 18 weeks to assess the combined response of growth and storage of carbohydrate and nitrogen in seedlings during their first year of growth in the nursery, as well as their subsequent field performance over the next 2 years. At the end of nursery stage, high nutrient supply increased nitrogen storage in both species, increased carbohydrate concentration in Q. mongolica but decreased that in P. tabuliformis seedlings. P. tabuliformis showed higher winter mortality than Q. mongolica but field mortality of P. tabuliformis decreased with an increase in fertilizer dosage. Our findings suggest that P. tabuliformis seedlings exposed to 100 mg N per plant can mitigate the field winter mortality although it could be still under deficiency status. Given lower winter mortality in Q. mongolica seedlings, being exposed to at least 100 mg N per plant in the nursery can produce nutrient-loaded seedlings, and therefore can be considered for restoration programs in areas affected by low winter temperature. [ABSTRACT FROM AUTHOR]

Abstract—The mass drying of the eastern spruce (Picea orientalis (L.) Link) in Teberdinskyii Nature Reserve (North Caucasus) was studied. The main cause of the drying was an outbreak of the number of bark beetles (Ips typographus L.), mass reproduction of which occurred in the hot seasons of 2012 and 2015. The existing undergrowth was not affected. By 2019, seven years after the beginning of the mass drying of spruce, the majority of the drying groups had died out, and single active bark beetle foci had been noted. There are almost no live spruce trees in the upper layer left. In small numbers, they have been preserved in the Dombai forest in mixed stands of Picea orientalis (L.) Link, Abies nordmanniana (Stev.) Spach, and Fagus orientalis Lipsky. As our study showed, the stands of two of the four forest areas of the reserve originated in a treeless space (250 and 350 years ago). Subsequently, three of the four underwent one strong, but local disturbance during their existence. Reconstruction of the history of dark coniferous stands of the surveyed forest areas shows a high capability for natural self-healing of the Teberda fir–spruce forests after massive disturbances. In the near future (after the fall of dead wood, which is already happening), the stands of the sample plots (SPs) will be a sparse forest of Abies or Abies with Fagus, and the majority of the sample plots will become open stands with single Abies trees. The modern mass drying of the eastern spruce as a result of bark-borne epiphytotics has a much larger scale of disturbances both in the area and in the degree of destruction of the stand. This is fundamentally different from the disturbances of the past. In this situation, the shortage of seeds will have a particularly negative impact. Therefore, the preservation of the preliminary coniferous undergrowth is especially important. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis Franch. is an economically and ecologically important pine endemic to southwest China. A large number of low-quality and low-efficiency individuals have appeared in P. yunnanensis forests due to climate change, environmental stress, and human overexploitation. There is a lack of comprehensive information about the genetic diversity, population structure and a core germplasm collection establishment with individuals taken across its natural range. Understanding the important information will be invaluable for germplasm efficient conservation and utilization. A total of 287 individuals from 10 populations across its range were analyzed using 17 polymorphic microsatellite markers. The research revealed P. yunnanensis was a typical outcrossing plant (Fis = − 0.1), maintaining moderately high genetic diversity (He = 0.540). The continuous distribution and wind-dispersal traits of two-sacs pollen and winged seeds may have promoted gene flow (Nm = 12.71) and lessened genetic differentiation between populations (Fst = 0.023). There was a lack of significant isolation by distance (P = 0.07). Geographical and ecological isolation following the uplift of the southeastern margin of the Tibetan Plateau may have contributed to the formation of three discrete groups (K = 3). A core collection of 72 individuals (25% of the whole collection) was established, of which genetic diversity parameters showed no-significance from the whole collection. In situ conservation of the three populations (XC, CY, and XP) showing distinct genetic diversity was recommended, and ex situ conservation for individuals with private alleles. The core collection was recommended as a possible germplasm resource for tree breeding and improvement. [ABSTRACT FROM AUTHOR]

A dataset of relevés for native forest types, including spruce, pine, and broad-leaved forests was created as a result of route surveys of strict scientific forest reserves in the Moscow region (boreo-nemoral zone). These relevés can be considered as a "benchmark" of native forest communities in comparison with young, secondary, and anthropogenically disturbed forests. The purpose of the work is to determine the species diversity indicators for undisturbed (by logging or recreation) native forest communities in the main forest types in the Moscow region. Classification of relevés into syntaxa (forest types) was carried out according to the principles of the V.N. Sukachev's school (based on habitat features and the composition of diagnostic groups of species) with further refinement of the results by ordination of relevés in multidimensional axes of detrending correspondence analysis (DCA). Biodiversity indicators (for an area of 300 m2), such as the alpha diversity, the Shannon index, and the rank abundance curves were calculated for the first time for native undisturbed forests of the Moscow region using a unified approach. The maximum species diversity of the tree layer (A) was observed in mixed coniferous-broadleaved forest types – Pineta composita (4.9) and Piceeta composita (4.4). The maximum species diversity of the shrub layer (B2) was observed in Piceeta composita (6.1) and Piceeta oxalidosa (5.3). The maximum species diversity of the field layer (C) was observed in two nemoral spruce forest types—Piceeta composita and Piceeta oxalidosa (over 29). The maximum species diversity of the bottom layer (D) was observed in Vaccinium-type pine forest (7.6). In general, the maximum species diversity for a forest type (all layers) was observed in the nemoral spruce forest types, Piceeta oxalidosa and Piceeta composita (ca. 43) with the highest values of the Shannon index (ca. 2.8), and the shape of rank abundance curve close to S-shaped. This shape of the curves is characteristic of mature natural communities. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine the forest road construction area and environmental impact area and to determine the tree injuries caused by forest road construction, the filling area covering the stand, and the distances of the trees directly affected by the tree injuries from the road axis. For this objective, a 700-m section of the forest road number 194 within the boundaries of the Alabarda Forest Management Sub-Directorate (Bolu/Turkey) was selected as the study area. The forest road environmental impact area was found by determining the rolling boundary of the backfill material with the differential global positioning system (DGPS) device. In addition, the position of the trees in this area in relation to the road and their damage conditions were determined, and wound sizes were measured. As a result of the study, the road construction impact area was 46479 m2, the average spread distance of the backfill material was 50.34 m, the average distance of the damaged trees from the road was 28.25 m, and the average distance of the trees that were not damaged was 35.52 m. In addition, a total of 1477 trees were identified in the construction impact area and 427 of these trees were damaged. According to the results of the statistical analyses, a statistically significant positive correlation was determined between bark wound area and diameter. In addition, a statistically significant negative correlation was determined between the distance of the trees from the road axis and the wound area and the height of the backfill. [ABSTRACT FROM AUTHOR]

The microbiological and some physicochemical properties of iron-illuvial soddy podburs (Entic Rustic Podzols) under Scots pine forests and gray-humus typical light loamy soils (Umbrisols) under secondary birch forests in central areas of the Zabaikalsky krai were studied. Fires result in a decrease in the sum of exchangeable bases, total nitrogen, and available potassium and phosphorus along with an increase in the C : N ratio in soddy podburs of pine forests; the opposite tendencies are observed after fires in gray-humus soils of birch forests. The humus content in the upper soil horizon decreases only after high-severity fire in the recently burned Scots pine forest and increases in all other sites. A decrease in soil acidity is observed at all burned sites. High-severity fires lead to a significant decrease in the content of microbial biomass and the intensity of basal respiration, as well as to changes in the structure of ecotrophic groups of microorganisms in the upper mineral part of soils to a depth of 10 cm, while low-severity fires mainly affect the duff. The qCO2 coefficient increases 2–5 times in the duff and 1.5–2 times in the humus horizon only after high-severity fires. In the recently burned Scots pine forest, the storage of microbial biomass and microbial production of carbon dioxide significantly decrease to a depth of 10 cm of the mineral soil layer. At the steppe site formed after repeated burning in the Scots pine forest and at the birch forest after high-severity fire, the microbial biomass carbon decreases by 15–20%, and the microbial production of CO2 increases by 10–20%. The considered post-fire transformation of the structural and functional parameters of soil microbial cenosis, as well as a 20–40% decrease in the pool of microbial biomass carbon in all the soils after fires predetermine a long period of soil recovery after fires in the light coniferous and deciduous forests in the central part of the Zabaikalsky krai. [ABSTRACT FROM AUTHOR]

Using biomass residues of any nature has gained more and more importance over time. In this work, the adsorptive and energetic capacity of biochar produced from a dry pine cone or strobilus residues of Pinus elliottii by torrefaction in the range of 200 and 300 ∘ C was evaluated. Raw strobilus pellets (P0) and their biochars (P200 to P300) were produced by two distinct routes of obtaining and then assessed for integrity in the water, thermal stability by TG/DTG and DTA, and composition by proximate, ultimate analysis, and ATR-FTIR spectra. As for energy use, the HHV ranged from 18.5 to 22.3 MJ kg - 1 from P0 to P300. In addition, other energy parameters such as mass and energy yields (MY and EY), enhancement factor (EF), energy-mass co-benefit index (EMCI), severity factor (SF), and torrefaction severity index (TSI) were evaluated. The reduction of MY from P200 to P260 was 14.4%, while for EY, it was 9.2%. About P300, the decline was 34.6 and 25.3% for MY and EY, respectively. Adsorption isotherms showed favorable interaction between methylene blue (MB) and biochars, with the best values for biochars being P220 to P260. All adsorption isotherms are L-type, indicating physical adsorption in low-porosity solids that tend to form multilayers. However, with the increase in torrefaction temperature, there was a decrease in functional groups on the biochar surface, increasing its hydrophobicity and decreasing the adsorption capacity of MB. To better elucidate the adsorptive process of biochars, isothermal models such as Langmuir, Freundlich, DRK, and Temkin were applied and evaluated. Results indicated P260 with better use as an adsorbent and subsequent energy use. [ABSTRACT FROM AUTHOR]

Due to the ongoing climate changes, temperate forests are increasingly exposed to fires. However, until now the functioning of post-fire temperate forest ecosystems with regard to used forest management method has been weakly recognized. Here, we examined three variants of forest restoration after fire (two variants of natural regeneration with no soil preparation—NR, and artificial restoration by planting following soil preparation—AR) regarding their environmental consequences in development of post-fire Scots pine (Pinus sylvestris) ecosystem. The study was conducted using a 15-year timespan in a long-term research site located in the Cierpiszewo area (N Poland) being one of the biggest post-fire grounds in European temperate forests in last decades. We focused on soil and microclimatic variables as well as on growth dynamics of post-fire pines generation. We found that the restoration rates of soil organic matter, carbon and most studied nutritional elements stocks were higher in NR plots than in AR. This could be primarily linked to the higher (p < 0.05) density of pines in naturally regenerated plots, and the subsequent faster organic horizon reconstruction after fire. The difference in tree density also involved regular differences in air and soil temperature among plots: consistently higher in AR than in both NR plots. In turn, lower water uptake by trees in AR implied that soil moisture was constantly the highest in this plot. Our study delivers strong arguments to pay more attention to restore post-fire forest areas with the use of natural regeneration with no soil preparation. [ABSTRACT FROM AUTHOR]

The factors governing the dynamics of tropical rainforest (TRF) and humid native savannas are little understood. In Mexico, both biomes are critically endangered owing to land-use change. Tropical pine plantations established in such sites might alter the savanna-TRF dynamics helping to elucidate the underlying factors of the vegetation dynamics in lowland humid tropics. This study aims to investigate the role of Pinus caribaea plantations on the savanna-TRF dynamics in the Gulf of Mexico coastal plain in areas where both biomes are close to one another. Such plantations were established in areas previously occupied by savannas and close to TRF and savanna fragments. Due to unusual circumstances, the plantations remained virtually unmanaged after being planted. We found that after 28–33 years of growth, the understory of pine plantations was similar to that of the TRF in tree species composition, species richness, stem density, and basal area. Pine trees cannot become established under the canopy of TRF, savanna trees, and pine plantations. The understory of savanna trees is unsuitable for establishing most tree species, including savanna trees. Pinus caribaea can alter the TRF-savanna dynamics by facilitating the establishment of TRF species in their understory in areas occupied by savannas, probably due to a combination of properties of both savanna (e.g., fire tolerance) and pioneer TRF (e.g., fast-growing rates) tree species. Thus, our results suggest that exotic pine plantations could be promising tools for TRF regeneration and suppressing savanna regeneration, thus creating a dilemma on what to preserve and restore. [ABSTRACT FROM AUTHOR]

Healthy soils are the second C sink on Earth, and this sink could last for hundreds or even thousands of years as stable soil organic matter (SOM). Forest soils, in particular, have the potential to store significant amounts of C, however, the amount of C sequestered and the carbon-to-nitrogen (C/N) ratio of soil organic matter (SOM) depend on the vegetation influencing the soil. In the last decades, mixed stands have aroused great interest among the scientific community, but it is still necessary to intensify research on its effect on soils and their C storage capacity. In this study, we assess soil C sequestration potential in soil and litter of mixed and pure stands of Scots pine and beech (Pinus sylvestris–Fagus sylvatica). Three triplets (9 forest plots), two located in Southern Poland and one in Southern Germany were studied. A total of 40 circular subplots of 5 m radius were selected within the triplets, covering a wide range of species mixture, and soil and litter were sampled. Data were analyzed at two scales (plot-level and microsite-level) to determine which option is more appropriate when studying the mixing effect on SOM. Cstock in forest floor ranged between 2.5 and 11.1 Mg C ha−1 and in mineral soil between 39.6 and 337.8 Mg ha−1. According to our findings, the percentage of species mixture primarily impacted the forest floor rather than the mineral soil. On the forest floor, stands with 25–50% pine in the mixture were found to have a C/N ratio between 20 and 30, which indicates an equilibrium state between mineralization and immobilization. In the mineral soil, total organic C was the only variable affected by mixture percentage (p < 0.1). Finally, microsite-level scale proved to be the most appropriate when studying tree stand composition effect on SOM, as the plot-level scale diluted or masked some effects. [ABSTRACT FROM AUTHOR]

Pinus densiflora and Pinus thunbergii are important forest tree species in the DPR Korea due to their ecological adaptability and versatile uses, including timber, medicinal, and cosmetic production. P. thunbergii 'Kumyahuksong' is a significant windbreak tree species on the coast due to its high salt tolerance, pest resistance, and rapid growth. Understanding the genetic relationships of Pinus species, with the potential for natural crosses, would assist forest establishment and conservation strategies. In this study, the genetic relationship among 63 germplasms of pine species were analyzed using RAPD and ISSR markers. The populations of both species and cultivars displayed significant genetic differentiation, as evidenced by the high FST values ranging from 0.53 to 0.72. PCA and UPGMA clustering analyses revealed that the samples could be separated into major clusters according to their species. Firstly, P. densiflora and P. thunbergii were separated, followed by the separation of P. thunbergii 'Kumyahuksong'. The Bayesian Structure analysis further emphasized the distinctiveness of P. thunbergii 'Kumyahuksong', particularly at K = 3, where it was presented as a distinct group. Despite the 'Kumyahuksong' cultivar indicated higher inbreeding (FIS = 0.261), it was also found to have a higher number of observed and effective alleles and polymorphisms compared to P. thunbergii. These results confirm the cultivar status of P. thunbergii 'Kumyahuksong', and also indicate that its exceptional phenotypic characteristics are likely due to its specific genetic background. Identification of natural crosses and fingerprinting of such individuals are valuable to effectively select materials in breeding programs of P. thunbergii, and the related species. [ABSTRACT FROM AUTHOR]

The results of karyological and cytogenetic studies of populations of conifer species from the families Pinaceae and Cupressaceae growing under extreme conditions have been summarized. A chromosomal variability has been revealed in coniferous plants growing at the southern and northern borders of their natural habitats, at ecological limits of distribution, in anthropogenically disturbed ecosystems, and under introduction conditions. A high frequency of changes in the number of chromosomes (mixoploidy, aneuploidy, and polyploidy) and their morphology has been observed. Different types of chromosomal anomalies (ring and polycentric chromosomes, chromosome fragments, and multiple chromosomal abnormalities), chromosome agglutination, mitotic and meiotic abnormalities, and the appearance of B chromosomes have been revealed. Using classical methods and fluorescent in situ hybridization (FISH), a polymorphism of nucleolar-forming regions of chromosomes has been studied and features of the 5S and 45S ribosomal DNA loci have been revealed. [ABSTRACT FROM AUTHOR]

A cytogenetic study of four embryogenic cell lines (CLs) of Siberian larch (Larix sibirica Ledeb.) of different ages, including young (two 4-month and one 16-month) and long-term proliferating (11-year) CLs has been carried out. Three CLs are diploid, and their karyotypes contain the number of chromosomes typical for this species (2n = 24). A 16-month CL capable of forming somatic embryos is aneuploid (2n = 25). This CL is probably characterized by a trisomy in one of the submetacentric chromosome pairs. A long-term proliferating CL, from which viable fruiting clones have been obtained, retained a diploid number of chromosomes for all 11 years of cultivation and still remained genetically stable. The karyotype of coniferous plants is characterized by high stability, and the most species from the family Pinaceae, to which the genus Larix Mill. belongs, contain 24 chromosomes (2n = 24). Therefore, the detection of cytogenetically stable cell lines with an altered chromosome set is of great interest for genetic studies of this group of plants. The identification of stable diploid cell lines is important for genetic and breeding studies aimed at the creation of highly productive plantations with specified hereditary properties. [ABSTRACT FROM AUTHOR]

This article presents the results of a comparative analysis of the radial increment of various larch species and provenances growing on a common ecological background in experimental forestry established in 1965–1967 on the Krasnoyarsk forest steppe by employees of the Sukachev Institute of Forest, Siberian Branch, Russian Academy of Sciences. The provenances of Siberian larch (Larix sibirica Ledeb.) from different elevation belts of the Southern Siberian Mountains, Gmelin larch (L. gmelinii Rupr.) from the Trans-Baikal and Zeya provinces (Eastern Siberia), and Japanese larch (L. leptolepis Gord) introduced from the island of Sakhalin are studied. Based on the cluster analysis of radial increment series, four groups of provenances are identified with different growth strategies, depending on the response to environmental factors: mountain–forest steppe and mountain–taiga provenances of Siberian larch and provenances of Gmelin larch from Transbaikalia. The provenance of Japanese larch from Sakhalin has formed a separate cluster. The highest values of radial increment are found in groups of mountain–forest-steppe provenances formed by Siberian larch and Gmelin larch trees introduced from East Siberian provinces. Low values of radial increment are noted in provenances of Siberian larch trees from Southern Siberia mountain–taiga zone and Japanese larch from Sakhalin. Dendroclimatic analysis is used to identify the relationship between the environmental variables of the introduction zone and the radial increment of the studied provenances. In the Krasnoyarsk forest steppe, the main factor limiting radial increment is the moisture content of the root layer in the middle of the growing season (July–August). Larch trees introduced from wetter habitats respond more strongly to an increase in water stress, while the radial increment of trees taken from drier habitats responds positively to an increase in the length of the growing season. [ABSTRACT FROM AUTHOR]

The genetic differentiation of Siberian larch (Larix sibirica Ledeb.) populations along the latitudinal gradient of climatic conditions was studied using high-throughput double digest restriction-site associated DNA sequencing (ddRADseq) data. We studied correlation of five main climatic variables with variation of 47.929 single nucleotide polymorphisms (SNPs). In total, 125 trees were genotyped and studied: 61 trees in four populations along the western geographic transect and 64 trees in four populations along the eastern geographic transect. Twenty-one SNPs with signatures of selection were identified, including nine outlier SNPs whose variation cannot be explained by selectively neutral processes, and 12 SNPs whose variation correlated with the environmental factors. Seven SNPs are located in the introns of mitochondrial genes NAD1, NAD2 and ribosomal protein gene L2, three are located relatively close to the mitochondrial genes encoding NAD2 and ribosomal proteins S7 and S11, one is located at a distance from the nuclear gene encoding a protein homologous to the microtubule-associated futsch-like protein of Arabidopsis thaliana, two in the tentative protein genes of unknown nature and three in contigs containing no genes, and for which no homologous sequences were found in the NCBI GenBank. [ABSTRACT FROM AUTHOR]

The DNA polymorphism of cenopopulations Larix sibirica Ledeb. and Picea obovate Ledeb. growing in different ecological conditions of the southern part of the Taimyr Peninsula has been studied and their genetic diversity in nuclear microsatellite loci is estimated: NA = 3.30, NE = 1.75, HO = 0.263, and HE = 0.366 in L. sibirica and NA = 2.92, NE = 1.59, HO = 0.351, HE = 0.338 in P. obovata. In general, a deficiency of heterozygous genotypes (F = 0.177) in the studied populations of Siberian larch and an excess of heterozygous genotypes (F = –0.051) in populations of Siberian spruce are noted. The genetic features of these species under the influence of technogenic emissions in the Norilsk industrial region are examined. In L. sibirica, a higher allelic diversity and a higher level of inbreeding are found in the cenopopulation from an ecologically safe area, while a higher level of heterozygosity and a lower value of the inbreeding coefficient are noted in the area with an increased level of pollution. A comparison of the cenopopulation samples of P. obovata has shown that the genetic structure of the stand from the ecologically favorable area is practically in equilibrium, while a 10% excess of heterozygotes is recorded in the more polluted area. Despite certain differences between the two studied species, in general, cenopopulations of L. sibirica and P. obovata growing in areas with an increased, but acceptable, level of technogenic load in the Norilsk industrial region are characterized by higher values of almost all parameters of genetic variability. We suggest that this pattern reflects the activation of adaptive processes in coniferous populations from extreme growing conditions. [ABSTRACT FROM AUTHOR]

A survey of Pinus cembra (Arolla pine) growing above 2800-m elevation was conducted in an ecoregion of the western Alps, where the highest treeline is at ~ 2650 m. The concepts of treeline and species line are discussed based on these field observations. The species line is the biological limit of a species, with inherited nested historical and current processes of high-mountain socio-ecosystems, while the treeline strictly concerns the limit of erect trees. Arolla pines were located and described (height, physiognomy) and their habitats recorded (elevation, slope, aspect). Individuals occurred up to 3200 m on east-facing steep and rocky slopes, with density decreasing exponentially with increasing elevation (halving every 40 m). East-facing habitats benefit from the main atmospheric moisture coming from the east (Italy). Individuals were mostly dwarf-shaped/prostrate (58%) or trees (39%; max height 3.8 m). They usually do not bear female cones, and needles are smaller by half compared to those of pines growing in lower elevation forests. Their morphology indicates harsh growing conditions due to elevation (aridity, frost) and disturbances (wind, snow, rockfall). Habitat preference primarily on grass-free steep rocky slopes and cliffs at high elevation is likely explained by the exclusion of livestock impacts (grazing, trampling). These pines constitute noteworthy "sky island" populations. Larix decidua and Pinus uncinata were also recorded above the treeline, but with lower maximum elevation and density than Pinus cembra. These observations highlight a complex pattern of species treeline in the western Alps, and probably beyond, with relevance to issues in conservation science. [ABSTRACT FROM AUTHOR]

Pines (n = 121 species) are important elements of forest ecosystems. They are economically and ecologically valuable and are often at the center of efforts to manage forests to reduce the risk of wildland fires. The pattern and process of pine seed dispersal and seedling establishment have important implications for maintaining healthy forests. 75% of pines are dispersed by wind, and 25% are dispersed by scatter-hoarding birds and rodents. Among the wind-dispersed pines, there are about 20 species that attract the attention of seed-caching animals that gather seeds and cache them in soil, so these species are dispersed by a combination of wind and animals. Animal-dispersed pines often occur in semi-arid ecosystems. The seeds cached by animals are a dynamic resource. Animals pilfer each other's caches, move them to new sites and recache them. Some seed reside in dozens of different cache sites between seed maturation and seed germination. Many pines are adapted to fire. This involves serotinous cones (about 24 species), which are dense, woody, and lignified and remain closed at maturity. Serotiny establishes a canopy seed bank that can persist for several decades. Shortly after fire, these cones open and shed seeds onto the burned landscape. Pines often mast, producing large crops of seeds at intervals of several years. These large cone crops satiate the appetites of specialist seed predators, resulting in increased seedling establishment and also increases the effectiveness of seed dispersal. In the past, pines have responded to climate change by shifting geographic ranges, and some pines appear to be responding to warming climates in a similar way. [ABSTRACT FROM AUTHOR]

A controlled experiment with Pinus tabuliformis Carr Seedlings was conducted to investigate the effect of nitrogen (N) deposition on the growth of plant organs by influencing the distribution of different hormones in plant organs and provide an important reference for understanding forestland governance and forest regeneration under global atmospheric N deposition. Seedlings of P. tabuliformis were subjected to 0, 3, 6, 12 g of N m−2 year−1, then growth parameters and hormone concentration (trans-zeatin riboside (ZR), gibberellin (GA1+3), indole acetic acid (IAA), abscisic acid (ABA)) in leaf, stem, total root, coarse root (diameters > 2 mm), fine root (1–2 mm) and finest root (0–1 mm) were measured. The results showed that N addition increased the growth of all the plant organs, decreased the ratio of underground (the whole root) to aboveground (leaf and stem) growth, which is in line with the functional balance hypothesis. Additionally, N addition increased the ZR concentration in stems, while decreasing the ABA concentration in leaves and whole roots and the GA1+3 concentration in whole roots, but IAA concentration was not significantly influenced by N addition. Furthermore, the stem growth was mainly affected by the synergistic effect of ZR and GA1+3, while the leaf and total root growth was mainly impacted synergistically by ZR and IAA. Additionally, the root growth at each diameter class was also regulated by different hormones. In conclusion, N addition can change the distribution pattern of endogenous hormones in different plant organs and roots of different diameter classes, thereby regulating growth of Pinus seedlings, and the changes in growth are the result of the coordinated regulation of various hormones. [ABSTRACT FROM AUTHOR]

Aims: Increasing global nitrogen (N) and phosphorus (P) deposition may affect the response mechanism of litter decomposition. We aimed to explore the responses of nutrient release and enzyme activities to exogenous N and P inputs. Methods: We conducted a two‑year field litterbag experiment in larch (Larix principis-rupprechtii) plantation at the Saihanba Forest Farm in Hebei Province, China. Four treatments, i.e., N addition (+ N), P addition (+ P), N and P addition (N + P), and control (CK) were designed and examined the overall effect of the fertilization treatments on the remaining mass, nutrients, and enzymatic activity. Results: In contrast to CK, the + N, + P, and N + P treatments significantly reduced the remaining leaf litter mass by 36.33%, 35.21%, and 38.50% at the end of the experiment, respectively. During the decomposition of leaf litter, + N had a significant effect on carbon (C) release and no significant effect on N and P release. + P promoted C release and significantly reduced the N remaining but increased the P remaining. Invertase activity decreased sharply in the early stage of decomposition. However, the activities of catalase, urease, and acid phosphatase declined in the middle stage in each treatment. The effect of + N on enzyme activities was not significant, while + P significantly increased urease activity. Conclusion: The results reveal that continuous N and P deposition could promote the litter decomposition rate, while altered the nutrient release pattern in larch plantation. [ABSTRACT FROM AUTHOR]

Peat is an important archive allowing the reconstruction of past mire environments and surrounding vegetation. The Pihoviny site, one of the oldest peat deposits in the Bohemian-Moravian Highlands, was analysed for macrofossils and pollen and compared with other profiles in the region. The local mire development started in the Late Glacial as sedge-moss quaking fen with tundra elements characterised by high mineral richness and groundwater level. During the Early Holocene, it developed through the rich fen with hummocks, willow and reed stage to the waterlogged spruce forest, which persisted for thousands of years until the post-mediaeval deforestation. The recent mire vegetation developed 300 years ago due to human-induced deforestation. Further, we revealed high regional synchronicity among pollen profiles in the Early-Holocene (10,000–9000 cal BP), when open-canopy pine-birch forests transformed into closed-canopy deciduous forests due to climate improvement. Contrary, the Late-Holocene transformation to beech-fir forests was not synchronous, suggesting another driver than climate, likely human activities. Although pollen of both late-successional trees occurred since the Early Holocene, their expansion began much later, 5500–3500 (beech) and 3500–2500 cal BP (fir). Numerous spruce macrofossils suggest its pollen's local origin in the waterlogged spruce forest. Our results support the need for active management to sustain open mire vegetation and prevent spontaneous forest regrowth, recently boosted by climate warming. Palaeoecological analyses reconstructed a mosaic of waterlogged spruce and terrestrial beech-fir forests in the landscape, which should be restored to increase forest resistance against bark-beetle breakdowns and other disturbances in future. [ABSTRACT FROM AUTHOR]