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Shared ancestral polymorphism and introgression are two main causes of chloroplast DNA (cpDNA) haplotype sharing among closely related angiosperms. In this study, we explored the roles of these two processes in shaping the phylogeographic patterns of East Asian Cerris oaks by examining the geographic distributions of randomly and locally distributed shared haplotypes, which coincide with the expectations of shared ancestry and introgression, respectively. We sequenced 1340 bp of non-coding cpDNA from Quercus acutissima (n = 418) and Q. chenii (n = 183) and compiled previously published sequence data of Q. variabilis (n = 439). The phylogenetic relationships among haplotypes were examined using a median-joining network. The geographic patterns of interspecifically shared haplotypes were assessed to test whether nearby populations have a higher degree of interspecific cpDNA sharing than distant ones. We identified a total of 27 haplotypes that were grouped into three non-species-specific lineages with overlapping distributions. Ancestral haplotypes were extensively shared and randomly distributed across populations of the three species. Some young haplotypes were locally shared in mountainous areas that may have been shared refugia. The local exchange of cpDNA resulted in an excess of similar haplotypes between nearby populations. Our study demonstrated that the haplotype sharing pattern among East Asian Cerris oaks reflected the imprints of both shared ancestral polymorphism and introgression. This pattern was also associated with the relatively stable climates and complex landscapes in East Asia, which not only allowed the long-term persistence of ancestral lineages but also connected the survived populations across refugia.

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With the rapid advancement of urbanization and industrialization, the contradiction between the social economy and resources and the environment has become increasingly prominent. On the basis of limited land resources, the way to promote multi-objective comprehensive development such as economic, social development and ecological and environmental protection through structure and layout regulation, so as to maximize regional comprehensive benefits, is an important task of current land spatial planning. Our aim is to obtain land-use-change data in the study area using remote-sensing data inversion and multiple-model simulation. Based on land suitability evaluation, we predict and optimize the land use structure of the study area in 2030 and evaluate and compare ecosystem services. Based on remote-sensing images and eco-environmental data from 1985 to 2014 in the study area, land use/land cover change (LUCC) and future simulation data were obtained by using supervised classification, landscape metrics and the CA-Markov model. The ecosystem services were evaluated by the InVEST model. The analytic hierarchy process (AHP) method was used to evaluate the land suitability for LUCC. Finally, the LUCC in 2030 under two different scenarios, Scenario_1 (prediction) and Scenario_2 (optimization), were evaluated, and the ecosystem service functions were compared. In the last 30 years, the landscape in the study area has gradually fragmented, and the built-up land has expanded rapidly, increased by one-third, mainly at the cost of cropland, orchards and wasteland. According to the suitability evaluation, giving priority to the land use types with higher environmental requirements will ensure the study area has a higher ecosystem service value. The rapid development of urbanization has a far-reaching impact on regional LUCC. Intensive land resources need reasonable and scientific land use planning, and land use planning should be based on the suitability evaluation of land resources, which can improve the regional ecosystem service function.

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The stomatal traits influence ecosystem carbon-water fluxes and play essential roles that enable plants to adapt to changing environmental conditions. However, how stomatal traits vary along a large climate gradient and whether stomatal traits coordinated with other leaf functional traits in response to environmental changes remain unclear. We investigated the stomatal density (SD), stomatal size (SS), and leaf traits (leaf area (LA), leaf mass per area (LMA), and vein density (VD)) of 44 in situ Quercus variabilis populations across Eastern Asia (24 to 51.8°N, 99 to 137°E) and 15 populations grown in a common garden, and evaluated their relationships with environmental factors. Stepwise multiple regression showed that the SD was significantly associated with mean annual precipitation (MAP), LMA, and VD, and the SS with latitude, mean annual temperature (MAT), mean monthly solar radiation (MMSR), and VD. The SD was positively correlated with the LMA, while the SS was negatively correlated with the VD. The SD and LMA increased with decreasing precipitation, which indicated that they may coordinate to commonly enhance plant resistance against drought. The SS decreased; however, the VD increased with temperature. This implied that plants might further reduce their SS by increasing VD limitations under global warming. In the common garden, plants exhibited a higher SD and VD and lower SS and LA compared to those in the field; however, no relation between the stomatal and leaf traits was observed. Our results suggested that stomatal traits have high environmental plasticity and are highly coordinated with other leaf functional traits in response to environmental changes. Nevertheless, this coordination may have been formed through long-term adaptations, rather than over short time spans.

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As an alternative for phospholipid fatty acid (PLFA) analysis, a simpler ester linked fatty acid (ELFA) analysis has been developed to characterize soil microbial communities. However, few studies have compared the two methods in forest soils where the contribution of nonmicrobial sources may be larger than that of microbial sources. Moreover, it remains unclear whether the two methods yield similar relationships of microbial biomass and composition with environmental variables. Here, we compared PLFA and ELFA methods with respect to microbial biomass and composition and their relationships with environmental variables in six oriental oak (Quercus variabilis) forest sites along a 1500-km latitudinal gradient in East China. We found that both methods had a low sample-to-sample variability and successfully separated overall community composition of sites. However, total, bacterial, and fungal biomass, the fungal-to-bacterial ratio, and the gram-positive to gram-negative bacteria ratio were not significantly or strongly correlated between the two methods. The relationships of these microbial properties with environmental variables (pH, precipitation, and clay) greatly differed between the two methods. Our study indicates that despite its simplicity, the ELFA method may not be as feasible as the PLFA method for investigating microbial biomass and composition and for identifying their dominant environmental drivers, at least in forest soils.

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The landscape patterns of plantations (PT) are the results of human disturbances on local vegetation, and in turn, differ greatly from natural forests (NF), since the patterns strongly influence the natural circulation of material and energy. There is a need to understand the differences of landscape patterns between PT and NF, to establish a near natural afforestation strategy. This study chose three typical silvicultural counties in the middle reaches of the Yangtze River as the research areas and compared the landscape patterns of NF and PT, with other land use types (grassland, GL; cropland, CL; shrubland, SL; orchard, OR; built-up land, BUL; bare land, BL; and water bodies, WB). The results revealed that the areas of PT accounted for 7.67%, 12.05%, and 18.97% of three counties, bigger than GL, OC, BUL, BL, and WB, as one of main land use types. The landscape patterns of PT (mean patch size between 2.06 to 6.05 ha) were more fragmented than NF (mean patch size between 5.83 to 53.91 ha). NF areas increased along the relative altitude gradient, from 0 to 2500 m, while PT areas peaked from 100-1000 m. The higher the altitude, the more typical the zonal distribution of PT, the more aggregated the NF. NF had significant negative correlations with BL, BUL, CL, PT, GL, and OC, which suggest that human activities had seriously interfered with NF. Although PT as an ecological protection strategy was increasing, the landscape patterns of PT were obviously different from NF. This may affect the material energy flow in the ecological environment. The results in the present study have great implications in the other regions in China and the relevant parts of the world where natural forests were heavily disturbed.

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Parasites obtain energy and nutrients from the host, and their body size is also usually limited by host size. However, the regulatory mechanisms that control the plasticity of parasite body sizes and the stoichiometric relationships with their hosts remain unclear. Here we investigated the concentrations of 14 elements (C, H, O, N, P, S, K, Na, Ca, Mg, Al, Fe, Mn, and Zn) in the acorns of three oak species (Quercus spp.), in their endoparasitic weevil (Curculio davidi Fairmaire) (Coleoptera: Curculionidae) larvae and in the larval feces, and the weight of weevil larvae within different hosts in a warm-temperate zone of China. Our results showed that the three acorn species exhibited significant differences in C, H, O, P, K, Mg, and Mn concentrations. However, in the weevil larvae, only P, Mn, and C:P ratio revealed significant differences. Weevil larvae preferentially absorbed and retained N, Zn, Na, and P, whereas Mn, K, Ca, and O were passively absorbed and transported. The weevil larvae weight was associated with acorn stoichiometry, and positively correlated with acorn size. Weevil larvae P decreased, but Mn and C:P increased with their weight, implying highly variable in somatic stoichiometry are coupled with the plasticity of body size. Interestingly, weevil larvae weight was negatively correlated with acorn infection rate, indicating small-size parasitic insects might have higher fitness level in parasite-host systems than larger-size ones. Our results suggest that variation in P, Mn, and C:P in parasites may play critical roles in shaping their body size and in improving their fitness.

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BACKGROUND: Phosphorus (P) -rich soils develop in phosphorite residing areas while P-deficient soils are ubiquitous in subtropical regions. Little has been reported that how metabolites participate in the seed development and the processes involved in their coping with contrasting-nutrient environments. RESULTS: Here we quantified the metabolites of Quercus variabilis acorns in the early (July), middle (August), late (September) development stages, and determined element (C, H, O, N, P, K, Ca, Mg, S, Fe, Al, Mn, Na, Zn, and Cu) concentrations of acorns in the late stage, at geologically-derived contrasting-P sites in subtropical China. The primary metabolic pathways included sugar metabolism, the TCA cycle, and amino acid metabolism. Most metabolites (especially C- and N-containing metabolites) increased and then decreased from July to September. Acorns between the two sites were significantly discriminated at the three stages, respectively, by metabolites (predominantly sugars and organic acids). Concentrations of P, orthophosphoric acid and most sugars were higher; erythrose was lower in late-stage acorns at P-rich sites than those at P-deficient sites. No significant differences existed in the size and dry mass of individual acorns between oak populations at the two sites. CONCLUSIONS: Oak acorns at the two sites formed distinct metabolic phenotypes related to their distinct geologically-derived soil conditions, and the late-stage acorns tended to increase P-use-efficiency in the material synthesis process at P-deficient sites, relative to those at P-rich sites.

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The leaves and seeds of plants frequently function as the source and sink organs for distinct metabolites, which can interactively vary in response to adverse site conditions. Subtropical soils are typically characterized as having deficient phosphorus (P), calcium (Ca), and magnesium (Mg), with enriched aluminum (Al) and iron (Fe), while Al and manganese (Mn) are toxic at low pH. It remains largely unknown how leaf- and seed-sourced metabolites are synergistically linked to adapt to P-variable soils for trees in subtropical areas. Here we quantified the metabolic and elemental profiling in the mature leaves and immature seeds of Quercus variabilis at contrasting geologically-derived phosphorus sites in subtropical China. The results revealed that carbon (C) and nitrogen (N) based metabolites (primarily sugars and organic acids), as well as enzyme- and protein/nucleic acid-related elements (N, P, Mg, and Mn) played important roles toward characterizing the profiling of metabolites and ionomes in leaves and seeds at two site types, respectively. These metabolites (sugars, amino acids, and fatty acids) and elements (N, P, Mg, and Mn) of seeds were closely related to the sugars, organic acids, and elements (N, P, Mg, and Mn) of leaves at the two site types. For the most part, the content of N and P in the soil affected the accumulation of materials (such as, starchs and proteins) in seeds, as well as N and P assimilation in leaves, by influencing C- and N-containing metabolites in leaves. These results suggested that correlated disparities of C- and N-containing metabolites, along with enzyme- and protein/nucleic acid-related elements in both leaves and seeds played important roles in plants to facilitate their adaptation to nutrient-variable sites in subtropical zones.

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Polycyclic aromatic hydrocarbons (PAHs) have toxic, teratogenic, mutagenic and carcinogenic effects on living organisms. Plants can function as pollutant bioindicators and bioaccumulators due to their wide surface distribution and specific responses to atmospheric pollutants. However, various plants exhibit significant differences in their capacities to accumulate PAHs. At present, research has mainly focused on the effects of leaf morphology and physiological characteristics, and few studies have evaluated the effects of the leaf surface on PAH accumulation. We aimed to assess the factors impacting the uptake and accumulation of PAHs by leaves. We selected 8 common tree species in Shanghai, China, and used supercritical fluid extraction technology to determine the content of PAHs in their leaves. Specific measurements of leaf area, width/length, wax content, and stomatal density were applied to index the morphological and physiological characteristics; surface roughness, surface free energy, polar components, and dispersion components were compiled into an adsorption performance index. Principal component analysis (PCA) and canonical correlation analysis (CCA) were used to assess the effects of different leaf characteristics on PAH accumulation. We found that the mean concentrations of ΣPAHs ranged from 300 to 2000 ng·g-1 and that the proportions of different benzene rings were significantly different among the different tree species. Leaf morphology and physiological characteristics had more significant effects compared to surface adsorption. CCA showed a significant negative correlation between leaf morphological characteristics and wax content, but had no significant correlation with surface adsorption. Low-molecular-weight PAHs were found to be mainly affected by the morphological characteristics, while medium- and high-molecular-weight PAHs were influenced by wax content and adsorption. Our conclusions provide a theoretical basis for the establishment of a reliable plant atmosphere-monitoring system and a method for screening tree species with strong PAH adsorption capacity.

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It is well established that land use change can have a profound impact on soil physicochemical properties but the associated changes in soil microbial communities are poorly understood. We used long-term research sites in a subtropical alluvial island of eastern China to measure changes in soil physicochemical properties and microbial community abundance and composition (via phospholipid fatty acid (PLFA) analysis) and function (via extracellular enzyme activity) across different land use types developed on the same soil matrix, including a camphor (Cinnamomum camphora) plantation, a chronosequence of differently aged dawn redwood (Metasequoia glyptostroboides) plantings, a deforested land and a rice paddy. We hypothesized that afforestation could improve soil quality by enhancing carbon (C) and nitrogen (N) contents, microbial biomass and enzyme activities, but that this effect would vary depending on forest age and tree species. Soil C and N concentrations, PLFA abundances and activities of decomposition enzymes (ß-glucosidase, urease, alkaline phosphatase and catalase) in older plantations all increased significantly compared to cropland. These variables changed little or decreased in deforested land compared to cropland. These variables also increased with planting age in the dawn redwood plantings. Soils under camphor plantations had higher soil nutrient contents, microbial biomass and lower enzyme activities than dawn redwood soils with similar age. We also found some significant relationships between soil chemical and biological properties: PLFA abundances were positively related to soil organic matter (SOM) contents; the fungal-to-bacterial ratio and fungal relative abundance were correlated positively with SOM contents and negatively with C/N ratio; both soil PLFA abundances and enzyme activities were positively linked with soil inorganic N content and potential net N mineralization rate; ratio of specific C, N and P (phosphorus) acquisition activities was limited to 10: 1: 10 across land use types. Our study underscores the fact that land use type can have a profound impact on soil microbial communities; in addition, tree species and planting age also play significant roles in afforestation.

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Titanium dioxide nanoparticles (nano-TiO2) have been widely applied in daily life and subsequent problem on the potential health risk are raised. Studies on the toxicity of nano-TiO2 have shown that they could lead to toxic effects on human and environment. However, the mechanisms are still unclear. We investigated the change of amino acid levels in L929 cells after nano-TiO2 exposure using gas chromatography with time-of-flight mass spectrometry (GC/TOFMS)-based metabolomics approach. Spectral profiles were subjected to multivariate statistics, namely, Principal Component Analysis (PCA), and Orthogonal Projections to Latent Structures-Discriminant Analysis (OPLS-DA). Using MetaboAnalyst 2.0, it was found that 7 metabolic pathways (impact-value >0.10) among the regulated pathways were significantly perturbed. Twelve distinct amino acids are identified from these pathways, including L-α-alanine, ß-alanine, glycine, L-aspartate, L-methionine, L-cysteine, glutamate, L-pyroglutamate, L-asparagine, L-glutamine, S-adenosylmethionine, and L-lysine. These results show that the disturbed amino acids played an important role in the nano-TiO2-induced cytotoxicity. Along with earlier findings, we successfully used the metabolomics approaches to manifest nano-TiO2 toxicity through triggering cellular oxidative stress, energy damage and the inhibition of DNA and RNA synthesis.

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Decreasing temperature and increasing precipitation along altitude gradients are typical mountain climate in subtropical China. In such a climate regime, identifying the patterns of the C stable isotope composition (δ(13)C) in plants and soils and their relations to the context of climate change is essential. In this study, the patterns of δ(13)C variation were investigated for tree leaves, litters, and soils in the natural secondary forests at four altitudes (219, 405, 780, and 1268 m a.s.l.) in Lushan Mountain, central subtropical China. For the dominant trees, both leaf and leaf-litter δ(13)C decreased as altitude increased from low to high altitude, whereas surface soil δ(13)C increased. The lower leaf δ(13)C at high altitudes was associated with the high moisture-related discrimination, while the high soil δ(13)C is attributed to the low temperature-induced decay. At each altitude, soil δ(13)C became enriched with soil depth. Soil δ(13)C increased with soil C concentrations and altitude, but decreased with soil depth. A negative relationship was also found between O-alkyl C and δ(13)C in litter and soil, whereas a positive relationship was observed between aromatic C and δ(13)C. Lower temperature and higher moisture at high altitudes are the predominant control factors of δ(13)C variation in plants and soils. These results help understand C dynamics in the context of global warming.

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Using samples from eastern China (c. 25 - 41° N and 99 - 123° E) and from a common garden experiment, we investigate how Mg concentration varies with climate across multiple trophic levels. In soils, plant tissue (Oriental oak leaves and acorns), and a specialist acorn predator (the weevil Curculio davidi), Mg concentration increased significantly with different slopes from south to north, and generally decreased with both mean annual temperature (MAT) and precipitation (MAP). In addition, soil, leaf, acorn and weevil Mg showed different strengths of association and sensitivity with climatic factors, suggesting that distinct mechanisms may drive patterns of Mg variation at different trophic levels. Our findings provide a first step toward determining whether anticipated changes in temperature and precipitation due to climate change will have important consequences for the bioavailability and distribution of Mg in food chain.

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Increasing empirical evidence has documented variability in elemental composition within species. However, the extent, causes, and pattern of variability in consumer stoichiometry across a large geographical scale are not well understood. Here, we investigated this issue using a holometabolous insect, weevils (Curculio davidi Fairmaire). Larvae of this species store energy needed for diapause, and variable energy requirements across the geographic range of this species could lead to differences in body elemental composition. Our results showed that variability was high (assessed as the coefficient of variation (CV)) in larval body nitrogen (N) and phosphorus (P) (CV, 10% for N and 13% for P) compared to emerging adults (CV, 5% for N and 8% for P). Temperature-related factors explained more variation than other climatic factors and food for carbon (C), N and P in weevil. In warmer regions, larval C concentration was higher, while N and P were lower. The high C content of weevil larvae relative to both their food source and their adult stage was attributed to energy storage. Across the climatic gradient of its geographic range, larval body C content increased with mean annual temperature and decreased with average diurnal temperature range. This finding implies that temperature-related C storage drives the high variability in elemental composition of larvae across the climate gradient, and also effectively dampens the stoichiometric imbalance between consumers and food resources while serving as an energy reservoir for overwintering and metamorphosis.

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The biogeographical relationships between far-separated populations, in particular, those in the mainland and islands, remain unclear for widespread species in eastern Asia where the current distribution of plants was greatly influenced by the Quaternary climate. Deciduous Oriental oak (Quercus variabilis) is one of the most widely distributed species in eastern Asia. In this study, leaf material of 528 Q. variabilis trees from 50 populations across the whole distribution (Mainland China, Korea Peninsular as well as Japan, Zhoushan and Taiwan Islands) was collected, and three cpDNA intergenic spacer fragments were sequenced using universal primers. A total of 26 haplotypes were detected, and it showed a weak phylogeographical structure in eastern Asia populations at species level, however, in the central-eastern region of Mainland China, the populations had more haplotypes than those in other regions, with a significant phylogeographical structure (N(ST= )0.751> G(ST= )0.690, P<0.05). Q. variabilis displayed high interpopulation and low intrapopulation genetic diversity across the distribution range. Both unimodal mismatch distribution and significant negative Fu's F(S) indicated a demographic expansion of Q. variabilis populations in East Asia. A fossil calibrated phylogenetic tree showed a rapid speciation during Pleistocene, with a population augment occurred in Middle Pleistocene. Both diversity patterns and ecological niche modelling indicated there could be multiple glacial refugia and possible bottleneck or founder effects occurred in the southern Japan. We dated major spatial expansion of Q. variabilis population in eastern Asia to the last glacial cycle(s), a period with sea-level fluctuations and land bridges in East China Sea as possible dispersal corridors. This study showed that geographical heterogeneity combined with climate and sea-level changes have shaped the genetic structure of this wide-ranging tree species in East Asia.

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Stoma is the main routeway for water and gas exchange in terrestrial plants, playing an important role on the global water and carbon cycles. Stomatal traits, including stomatal density, stomatal shape, stomatal size, and stomatal index, are the long term adaptation result of plants to environmental factors during evolution, and sensitive to the changes of environmental factors. This paper reviewed the last 30 years research advances in the relationships between stomatal traits and environmental factors (e.g., air CO2 concentration, temperature, water, and light, etc. ) and the main relevant investigation methods, and proposed the main directions of future research in stomatal traits in context of climate change.

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Based on the observations of air temperature, soil temperature, and root systems of Pinus sylvestris var. mongolica plantations on southeastern Keerqin sandy land, the decline mechanisms of the plantations were analyzed from the aspect of the effects of temperature on the growth and survival of ectomycorrhizal fungi (ECM). The results indicated that ECM could hardly survive with in 0-5 cm soil layer because of its high temperature environment, but the temperature condition in 20-40 cm soil layer was suitable for the survival and growth of ECM. 78% of the roots of 13-42 years old P. sylvestris var. mongolica tress were distributed in 20-40 cm soil layer, which suggested that the existence of ECM in this soil layer inhibited or alleviated the decline of the P. sylvestris var. mongolica plantations, and was not the inducing factor of the plantations' top withering, low growth rate, and tree death. The lack of ECM in surface soil layer (0-5 cm) could be one of the main reasons leading to the death of seedlings root systems, and thus, the failure of P. sylvestris var. mongolica plantations' regeneration.

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With introduced sandy land Mongolian pine (Pinus sylvestris var. mongolica) seeds as test material, this paper studied the effects of polyethylene glycol (PEG)-simulated drought stress on their germination. The results showed that PEG could retard the germination of stressed seeds, and the germination rate, germination index, and germination potential were all decreased with increasing PEG concentration. The seeds treated with 30% PEG (about -1.20 MPa water potential) could not germinate at all throughout the experiment period, suggesting that 30% PEG or -1.20 MPa water potential was the threshold for the germination of Mongolian pine seeds. Under 10% PEG stress (about -0.20 MPa water potential), the lengths of radicle and hypocotyl were shorter, illustrating their growth be more sensitive to PEG-simulated drought stress, while the radicle/hypocotyl ratio was increased with increasing PEG concentration, indicating that Mongolian pine seeds had a stronger resistance to drought stress after germination. Drought stress might be a possible cause that inhibited the natural regeneration of Mongolian pine on sandy land.

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The storage and distribution of Korean pine seeds on Korean pine forest floor in Changbai Mountain Nature Reserve were investigated, and the data were compared with those in 1970s when the forest was little disturbed. Based on the dependence of natural regeneration of Korean pine on seed predating animals, the effect of commercial cone-picking on natural regeneration of Korean pine was discussed. The results showed that Korean pine seeds were generally berried under litter layer, and most of them were dropped during cone-picking. The density of Korean pine seeds was 1582-2640 x hm(-2), accounted for 0.3%-0.5% of that in 1970s. Furthermore, over 67.8% of these seeds were rotten. Unlike the seeds distributed by squirrel, many (46.7%-77.1%) of them distributed singly. Animals that pick seeds from cone and thus are important for natural regeneration of Korean pine have reduced their population or even disappeared in recent years because most Korean pine cone were collected by people. Therefore, cone-picking was one of the obstacles for natural regeneration of Korean pine in Changbai Mountain Nature Reserve.

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