Age-Related Conservation in Plant-Soil Feedback Accompanied by Ectomycorrhizal Domination in Temperate Forests in Northeast China.

This study investigates the effects of forest aging on ectomycorrhizal (EcM) fungal community and foraging behavior and their interactions with plant-soil attributes. We explored EcM fungal communities and hyphal exploration types via rDNA sequencing and investigated their associations with plant-soil traits by comparing younger (~120 years) and older (~250 years) temperate forest stands in Northeast China. The results revealed increases in the EcM fungal richness and abundance with forest aging, paralleled by plant-soil feedback shifting from explorative to conservative nutrient use strategies. In the younger stands, Tomentella species were prevalent and showed positive correlations with nutrient availability in both the soil and leaves, alongside rapid increases in woody productivity. However, the older stands were marked by the dominance of the genera Inocybe, Hymenogaster, and Otidea which were significantly and positively correlated with soil nutrient contents and plant structural attributes such as the community-weighted mean height and standing biomass. Notably, the ratios of longer-to-shorter distance EcM fungal exploration types tended to decrease along with forest aging. Our findings underscore the integral role of EcM fungi in the aging processes of temperate forests, highlighting the EcM symbiont-mediated mechanisms adapting to nutrient scarcity and promoting sustainability in plant-soil consortia.

Habitat suitability evaluation of invasive plant species Datura stramonium in Liaoning Province: Based on Biomod2 combination model.

Datura stramonium, as a major invasive plant in Liaoning Province, is difficult to be removed after its successful invasion, and is a great threat to ecological environment and biodiversity. To evaluate the habitat suitabi-lity of D. stramonium, we collected its geographic distribution data in Liaoning Province through field investigation and database query, and using the Biomod2 combination model, and investigated its potential and suitable distribution areas and main influencing environmental variables at present and under future climate change scenarios, respectively. The results showed that the combined model which composed of GLM (generalized linear model), GBM (generalized boosting regression model), RF (random forest model), and MaxEnt (maximum entropy model) had a good performance. By classifying the habitat suitability of D. stramonium into four categories: high-, medium-, low- and un-suitable habitats, we found that the high-suitable habitats were generally distributed in the northwest and south of Liaoning Province, with an area of about 3.81×104 km2, accounting for 25.8% of the total area. The medium-suitable habitats were mostly distributed in the northwest and central parts of Liaoning Province, with an area of about 4.19×104 km2, accounting for 28.3% of the total area. Slope and clay content of topsoil (0-30 cm) were the two main variables explaining the habitat suitability of D. stramonium, and the total suitability of D. stramonium first increased and then decreased with the increasing slope and clay content of topsoil in this region. Under future climate change scenarios, the total suitability of D. stramonium showed an expanding trend, and its suitability would be obviously increased in Jinzhou, Panjin, Huludao, and Dandong.

[Community structure of phyllosphere fungi associated with dominant tree species in a broad-leaved Korean pine forest of Changbai Mountain, Northeast China]. / é•¿ç™½å±±é˜”å¶çº¢æ¾æž—ä¼˜åŠ¿æ ‘ç§å¶é™ çœŸèŒç¾¤è½ç»“æž„.

Forest is the main component of terrestrial ecosystems that harbors about 40% of the existing species on the earth. As a vital component of biodiversity, phyllosphere microbes in the canopy play a critical and unique role in maintaining plant health, improving host resistance, and influencing global biogeochemical cycle. However, the studies on the community structure of phyllosphere fungi in natural forests are scarce as compared to that on rhizosphere microbes. Consequently, we know litter about how phyllosphere fungi associates with leaf traits. In this study, we analyzed fungal community composition of canopy leaves of six dominant tree species (i.e., Pinus koraiensis, Tilia amurensis, Quercus mongolica, Acer mono, Fraxinus mandshurica, and Ulmus japonica), in a broad-leaved Korean pine forest of Changbai Mountain Nature Reserve in Jilin Province, using high-throughput sequencing. We compared the differences of phyllosphere fungal community structure and functional groups of different dominant tree species. Moreover, 14 key leaf functional traits of their host trees were measured to investigate the relationships between fungal community composition and leaf functional traits. We found that the dominant phyla and class of phyllosphere fungi were Ascomycota and Basidiomycota, and Dothideomycetes and Taphrinomycetes, respectively. Results of LEfSe analysis indicated that all the tree species except Ulmus japonica had significant biomarkers, such as the Eurotiomycetes of Pinus koraiensis and the Ascomycetes of Quercus mongolica. The main functional groups of phyllosphere fungi were pathotroph. The results of redundancy and envfit analysis showed that functional traits related to plant nutrient acquisition as well as resistance to diseases and pests were the main factors influencing the community structure of phyllosphere fungi.

Ectomycorrhizal fungus-associated determinants jointly reflect ecological processes in a temperature broad-leaved mixed forest.

Ectomycorrhizal (ECM) fungi are closely related to vegetation compositions, edaphic properties, and site-specific processes. However, the coevolutionary mechanisms underlying the spatial distributions in floristic and ECM fungal composition in the context of biotic adaptations and abiotic variances remain unclear. We combine a total of 25 ECM fungus-associated environmental variables to impose three types of composite scores and then quantify the environmental gradients of geographical site, soil chemical property and vegetation functional trait across 122 grids of 20 m × 20 m in a 25-hm2 forest plot. Significant dissimilarities in vegetational and ECM fungal abundance and composition existed along the above environmental gradients. Specifically, a contrasting floristic distribution (e.g., Betula platyphylla vs. Tilia mandshurica) existed between the northeastern and southwestern areas and was closely related to the nutrient and moisture gradients (with high levels in the west and low levels in the east). Furthermore, the ECM fungal communities were more abundant in the nutrient-poor and low-moisture environments than in the nutrient-rich and high-moisture environments, and the mixed-forest in the middle-gradient sites between the northeastern and southwestern areas harbored the highest ECM fungal diversity. These findings suggest that predictable within-site vegetation succession is closely related to ECM-associated determinants and the natural spatial heterogeneity of edaphic properties at a local scale.

[Effects of nitrogen and soil microbe on growth and photosynthesis of Fraxinus mandschurica seedlings.] / æ°®å’ŒåœŸå£¤å¾®ç”Ÿç‰©å¯¹æ°´æ›²æŸ³å¹¼è‹—ç”Ÿé•¿å’Œå ‰åˆä½œç”¨çš„å½±å“.

We examined the effects of nitrogen, soil microbe and their interactions on biomass allocation, growth and photosynthesis of Fraxinus mandschurica, a typical tree species in Changbai Mountain, through outdoor control experiments. In June 2017, an experiment with two-factor randomized block design was carried out. There were four treatments: control (F), nitrogen addition (FN), sterilization (FS), sterilization and nitrogen addition (FSN), six repetitive blocks, three repetitions per block, including 18 repetitions of each treatment. In mid-August 2018, we measured photosynthetic parameters and then harvested seedlings to measure biomass and growth parameters in September. The results showed that compared with F, FN significantly increased total biomass by 14%, basal diameter by 9%, chlorophyll content, net photosynthetic rate (Pn), stomatal conduc-tance (gs), transpiration rate (Tr) by 75%, 318%, 231%, 227% respectively. FS significantly increased total biomass by 13%, basal diameter by 9% and chlorophyll content, Pn, gs and Tr increased by 34%, 213%, 120% and 115%, respectively. FSN increased total biomass by 23%, basal diameter by 14%, chlorophyll content, Pn, gs and Tr increased by 81%, 672%, 312% and 273%, respectively. Nitrogen, soil microbe and their interactions had significant effects on biomass, growth and photosynthesis of F. mandschurica seedlings. Soil microbe would regulate the response of F. mandschurica seedlings to nitrogen.

[Spatio-temporal dynamics of woody plants seed rains in broad-leaved Korean pine mixed forest in Changbai Mountains form 2006 to 2017, China.] / 2006­2017年长白山阔叶红松林木本植物种子雨的时空动态.

Seeds are the basis for forest regeneration. To examine the composition and spatio-temporal dynamics of seed rains, a total of 150 seed traps of 0.5 m2 were installed in a 25 hm2 broad-leaved Korean pine (Pinus koraiensis) mixed forest plot in Changbai Mountains. With a total of 252 collections from May 2006 to September 2017, we collected 764299 mature and immature seeds which were belonged to 27 species, 17 genera, and 12 families. More than 90% of all collected seeds (704231 seeds) were from 13 canopy species. Seeds of four tree species, including Tilia amurensis, Fraxinus mandschurica, Acer mono, and Acer pseudo-sieboldianum could be collected every year from each trap. Mast-seeding was found in every canopy layer, but it happened one to two years earlier in the overstorey layer than midstorey and understorey layer. Almost all species produced seeds in autumn, with considerable spatiotemporal variation. Generally, the spatial variation of seeds was larger than temporal variation. Compared with annual variation coefficient of seeds in tropical forest of the Barro Colorado Island (BCI) and subtropical evergreen forest in the Gutianshan, annual variation coefficient of seeds in Changbai Mountains was higher, which supported the hypothesis that annual variation in seed rains would be lower in the tropics than that in higher latitudes.

[Factors influencing tree radial growth of three common species in broad-leaved Korean pine mixed forests in Changbai Mountains, China]. / 长白山阔叶红松林3ä¸ªå¸¸è§æ ‘ç§å¾„å‘ç”Ÿé•¿çš„å½±å“å› ç´ .

To understand the factors influencing tree radial growth, we analyzed the seasonal dynamics of tree growth of 3 common species (Pinus koraiensis, Tilia amurensis, Quercus mongolica), compared interspecific growth rates and explored the effects of size, neighborhood competition, soil and topography based on five years dendrometer bands monitoring data of the 3 common species in a broad-leaved Korean pine (P. koraiensis) mixed forest plot in Changbai Mountain, Northeast China. The results showed that the growth dynamics of 3 species were consistent. Trees began to grow in late May, thrived in July, grew at declining rates from late August and stopped growing in late October. Annual relative growth rates were significantly different among the species. Q. mongolica tended to grow faster than the other two species, and the differences of growth rates among the 3 species were especially large for small and medium trees. Tree growth rates of P. koraiensis and Q. mongolica were strongly decreased by neighborhood competition, while tree growth rate of T. amurensis was significantly related to tree size, soil and topography.

[Species composition and community structure of a spruce-fir forest and a larch forest on the northern slope of Changbai Mountains, Northeast China].

Spruce-fir forest is the best protected forest vegetation, while larch forest is intrazonal vegetation on the northern slope of Changbai Mountains. To further understand their species composition and community structure, we established a 4 hm2 forest permanent plot in each of these two forests in 2010. All free-standing plant species with DBH (diameter at breast height) ≥ 1 cm were mapped, tagged, and identified to species. The results showed that there were 9257 stems belonging to 8640 genotype individuals, 22 species, 6 genera and 12 families in the spruce-fir forest plot, while 4060 stems belonging to 3696 genotype individuals, 22 species, 8 genera and 16 families in the larch forest plot. Species composition in the two plots was very similar. Most of the species belonged to the Changbai Mountains plant flora. The analysis of species' importance values showed that there were dominant species in both communities. The spruce-fir forest was dominated by Abies nephrolepis and Larix olgensis, whose importance values accounted for 38.7% and 23.9% of the sum of importance values over all species in the plot, respectively. The larch forest was dominated solely by L. olgensis, whose importance value accounted for 61.9% of the sum of importance values over all species in the plot. Both forests were in good condition of regeneration and showed a reversed 'J' type in tree size distributions, at community level. However, different species showed different shapes in size distribution in the two forests. A. nephrolepis showed a reversed 'J' type size distribution in the spruce-fir forest, while L. olgensis with DBH ≥ 10 cm showed a hump-shaped distribution in the larch forest. Spatial distribution patterns of the main species changed differently with size class and spatial scales. Common species had different spatial distribution patterns in the two plots.

[Woody plant species composition and community structure in residual fragments of broad-leaved Korean pine mixed forests in Changbai Mountains area].

The broad-leaved Korean pine mixed forest represents the typical vegetation type of the eastern mountain area in Northeast China. However, due to the interference of human activities, the natural broad-leaved Korean pine forest only distributes in some residual fragments with unequal areas in Changbai Mountains and Small Hinggan Mountains. To compare and analyze the similarities and differences of broad-leaved Korean pine mixed forests in the different areas, we established six forest plots following the field protocol of the 50 hm2 forest plot in Panama (Barro Colorado Island, BCI) in 2012 in Changbai Mountain National Nature Reserve in Jilin Province and the eastern mountain area in Liaoning Province. All free-standing plant species with DBH (diameter at breast height) > or = 1 cm were mapped, tagged and identified to species. The results showed that there were 69 woody species in the six plots, comprising 42 genera and24 families. Aceraceae was the most species-rich family in all six plots. Most species belonged to the plant type of North Temperate Zone, with a minor subtropical plant species component. The statistics of species abundance, basal area, mean DBH, and importance value showed that there were obviously dominant species in each community. The DBH distribution of all individuals showed a reversed "J" type. However, the percentage of individuals in small size-class and large size-class varied in the six communities, which indicated that these communities were at different successional stages. Ranked by the importance value, the DBH distribution of the top three species in the six plots showed four distribution types: reversed "J" distribution, reversed "L" distribution, unimodal distribution, and partial peak distribution. Spatial distribution patterns of the main species in the six plots changed differently with species and size-class, and the distribution patterns of the same species varied in the different plots.

[Short-term death dynamics of trees in natural secondary poplar-birch forest in Changbai Mountains of Northeast China].

Taking the 5 hm2 sampling plot in the natural secondary poplar-birch forest in Changbai Mountains as test object, and based on the two census data in 2005 and 2010, an analysis was made on the main tree species composition and quantity, size class distribution of dead individuals, and regeneration characteristics of the main tree species in different habitat types of the plot in 2005-2010. In the five years, the species number of the individuals with DBH> or = 1 cm increased from 46 to 47, among which, 3 species were newly appeared, and 2 species were disappeared. The number of the individuals changed from 16509 to 15027, among which, 2150 individuals died, accounting for 13% of the whole individuals in 2005, and 668 individuals were newly increased. The basal area of the trees increased from 28.79 m2.m-2 to 30.55 m2.m-2, with that of 41 species increased while that of 6 species decreased. The decrease of the basal area of Betula platyphylla and Populus davidiana accounted for 72.3% of the total decrease. Small individuals had higher mortality, as compared with large ones, and the mortality of the individuals with DBH<5 cm occupied 65% of the total. B. platyphylla and P. davidiana contributed most in the dead individuals with large DBH. No difference was observed in the tree mortality among different habitat types, but the mortality of the individuals with different size classes showed greater variation.

[Composition and seasonal dynamics of litter falls in a broad-leaved Korean pine (Pinus koraiensis) mixed forest in Changbai Mountains, Northeast China].

In order to understand the composition and spatiotemporal dynamics of the litter falls at community level in a broad-leaved Korean pine mixed forest in Changbai Mountains, litter falls were collected from 150 containers in a 25 hm2 permanent plot in 2008. The leaf litters in the containers were from 35 tree species, accounting for 67.3% of the total number (52) of the tree species with DBH > or =1 cm in the plot. The litter falls had a weight 29.39 kg, equivalent to 3918.4 kg x hm(-2) among which, broad leaves, miscellany, needle leaves, and branches occupied 61.7%, 18.0%, 11.7%, and 8.6%, respectively. About 83.8% of the broad leaves were from Tilia amurensis, Fraxinus mandshurica, Quercus mongolica, Acer mono, and Ulmus japonica. The litter falls showed an evident seasonal dynamics, with the peaks occurred from 13 September to 10 October, e.g., the litter falls from T. amurensis and Pinus koraiensis peaked in 13-26 September, while those from Q. mongolica, U. japonica, and A. pseudo-sieboldianum peaked in 27 September to 10 October. There was a great difference in the mass of the litter falls among the containers, e.g., with 150-200 g litters in 68 containers and >500 g litters in 1 container. The species number of the litter falls in a container was 18 in maximum, and was 12 in common (32 containers). Litter falls mass was positively proportional to the sum of the basal area at breast height of parent trees in the plot, and the amount of the litter falls in the containers was related with the locations of the containers, exhibiting an evident spatial heterogeneity in the plot.

[Pinus koraiensis seed consumption by rodents and birds].

An investigation from 2006 to 2007 was made on the Pinus koraiensis seed consumption by rodents and birds in the broad-leaved P. koraiensis mixed forest and birch forest at the same altitude in Changbai Mountains. The results showed that in broad-leaved P. koraiensis mixed forest, rodents consumed more pinecone seeds than birds; while in birch forest, birds did more than rodents. In the two forests, the total number of pinecone seeds consumed by rodents was significantly higher than that consumed by birds (P < 0.01). In addition, rodents consumed more embedded seeds in broad-leaved P. koraiensis mixed forest than in birch forest, and the consumption amount in the two forests decreased with increasing embedded depth.

[Long-term effects of different management strategies on Larix gmelinii forests in Great Hing' an Mountains after the catastrophic fire in 1987].

In this paper, LANDIS model was used to study the effects of different management strategies on the larch (Larix gmelinii) forests of Tuqiang Forest Bureau on the northern slopes of Great Hing' an Mountains after the catastrophic fire in 1987. Three management strategies, i. e., natural regeneration if the catastrophic fire in 1987 was not happened (M1), natural regeneration after the catastrophic fire in 1987 (M2), and current management strategy after the catastrophic fire in 1987 (M3), were compared over a 300-year period. The results showed that the abundance of larch forests over 300 simulation years under the three management strategies had significant difference. In the whole Bureau, the abundance of larch forests under M2 was obviously lower than that under M1 and M3 over 300 years, and the abundance under M3 was lower than that under M1 at the beginning. Due to the reforestation after the catastrophic fire in 1987, the abundance of larch under M3 increased rapidly, and caught up with that under M1 after about 100 years. In addition, different forest management strategies also had significant influence on the age structure of larch forests, especially for mature and over-matured larch forests. The abundance of mature and over-matured larch forests under M1 was higher than that under M2. This abundance under M3 had tremendous decrease because of forest harvesting for about 10 years, and then, increased with time and would exceed that under M1 and M2 for over 100 years. Furthermore, in unburned areas and burned areas, the abundance of mature and over-matured larch forests also had significant difference over 300 simulation years under the three management strategies.

[Seasonal dynamics and spatial distribution patterns of herbs diversity in broadleaved Korean pine (Pinus koraiensis) mixed forest in Changbai Mountains].

In this paper, the species composition, seasonal dynamics, and spatial distribution patterns of herbs were examined in a 25 hm2 broadleaved Korean pine (Pinus koraiensis) mixed forest plot in Changbai Mountains. The results showed that the plot had a relatively high herbaceous richness, with 102 species belonging to 40 families and 84 genera, and the Shannon index, Simpson index, and Pielou index was 3.52, 0.96 and 0.75, respectively. The three indices varied dramatically with growth season, whereas the species abundance decreased linearly from early spring to autumn. The species richness and abundance showed irregular distribution, indicating that herbaceous species were microenvironment-dependent. Slope aspect had significant effects on herbaceous species richness and abundance. Northern and eastern slopes had higher species richness and abundance in early spring than southern and western slopes, whereas it was in adverse in late summer and autumn.