Search

Introduction: To investigate the differences in the response of radial growth of larch (Larix gmelinii) at varying altitude gradients to climatic factors, this study established tree-ring width chronologies of Larix gmelinii at altitudes of 900 m, 1,120 m and 1,300 m based dendroclimatology. Methods: We also employed R packages including "dplR," "static" and "moving" to determine the correlation between larch at different altitudes and climatic factors and to explore the sensitivity and stability between radial growth and the climate of larch at different altitudes in the northern part of the Greater Khingan Mountains Range in Northeast China. Results: The results revealed the radial growth of larch in high altitude areas to exhibit a downward trend due to climate warming, while the growth of trees in intermediate and low altitude areas showed an upward trend. The growth-- climate relationship exhibited a significant negative correlation between radial growth in low altitude larch (900 m) and temperatures in the current winter (February and March) and growing season (July, October of the current year, and October of the previous year) (p < 0.05). Moreover, high altitude larch (1,300 m) showed a significant negative correlation with temperature in January, March, and October of the current year (p < 0.05). However, in intermediate altitude areas (1,120 m), the radial growth of trees was significantly positively correlated with the temperature of the growing season (May, June and August). Precipitation in April was observed to promote the radial growth of low-altitude larch. Moving correlation analysis revealed that the inhibitory effect of low temperatures in winter and high temperatures in the growing season on the radial growth of larch at three altitudes gradually strengthened, transitioning from significant negative/positive correlations to significant positive/negative correlations along the altitudinal gradient. Discussion: Larch trees in high and low altitudes exhibited an increased sensitivity to winter and spring precipitation, while in the intermediate region, the inhibitory effect of growing season precipitation on larch radial growth continued to intensify. The results of the study have an important reference value for the indepth understanding of the growth dynamics of Larix gmelinii natural forests in the northern part of the Greater Khingan Mountains under climate change. [ABSTRACT FROM AUTHOR]

Ongoing climate change has a considerable influence on the seasonality, timing, and intensity of rainfall worldwide, and is also predicted to decrease snow cover in cold ecosystems. Larch is a widely distributed tree species in boreal Eurasia, calling for a comprehensive understanding of how larch adapts to changes in both rainfall and snowfall by adjusting carbon-water physiology. Here, we conducted a short-term rainfall (− 60% ambient rainfall; three-year) and snowfall (− 73% ambient snowfall; two-year) exclusions experiment in Larix gmelinii forest in northeastern China, and aimed to explore the responses of hydraulic (leaf pressure-volume traits, leaf and branch hydraulic conductivity and embolism resistance), stomatal (stomatal closure point and stomatal safety margin), and economic (photosynthetic rate, nutrient and non-structural carbohydrates contents) traits to rainfall and snowfall reductions. Despite the weak alternation of leaf and branch hydraulic traits, both rainfall and snowfall reductions significantly led to early stomatal closure and increased stomatal safety margins (the difference between stomatal closure point and xylem embolism threshold, describing drought resistance by merging both hydraulic and stomatal strategies). Reductions in rainfall and snowfall induced water or/and low-temperature stress, resulting in more conservative leaf economic traits, including a reduced photosynthetic rate, lower leaf nitrogen concentration, and higher leaf density. In addition, larch responded to reductions in rainfall and snowfall by up-regulating non-structural carbohydrates in the xylem, which helps repair embolism or lower the freezing point acting as osmolytes. Overall, our findings reveal that larch could adapt to the drought and snowpack reduction by strict stomatal regulation and investing non-structural carbohydrates in embolism repairing, at the cost of carbon assimilation. [ABSTRACT FROM AUTHOR]

Quantifying the relationship between radial growth of Larix gmelinii（Rupr.） Kuzen of different ages and climatic fac‐ tors, and provide decision making basis for adaptive management and management of natual Larix gmelinii（Rupr.） Kuzen forests. Therefore, based on the data of 159 Larix gmelinii（Rupr.） Kuzen. from Pangu Forest Farm of Tahe Forestry Bureau in Heilongjiang Province in 2022, this study adopted the method of systematic cluster method to divide the trees into young-age, middle-age and oldage group based on tree age. Then, using dendrochronology, standard chronology was established to analyze and compare the relation‐ ship between radial growth of trees of different age groups and climate factors, and multiple stepwise regression method was used to construct the prediction model of single tree radial growth sensitive to climate. The results showed that：1） The total sample explana‐ tory weight （EPS）, mean sensitivity （MS） and signal-to-noise ratio （SNR） of the （total group, old-age group, middle-age group, and young-age groups） were higher, which indicated that the standard chronology of Larix gmelinii（Rupr.） Kuzen retained abundant cli‐ mate information. 2） The main limiting factors for radial growth of Larix gmelinii（Rupr.） Kuzen were temperature in August of the current year, temperature from August to October of the previous year, and precipitation in February and July of the current year, and in July and December of the previous year. 3） There were significant differences in the response of Larix gmelinii（Rupr.） Kuzen to climate factors in different age groups. The radial growth of old-age Larix gmelinii（Rupr.） Kuzen was affected not only by the summer temperature of the current year but also by the summer temperature and precipitation of the previous year, showing a significant lag ef‐ fect, while the young and middle age Larix gmelinii（Rupr.） Kuzen were less affected by environmental factors. [ABSTRACT FROM AUTHOR]

Investigating the long-term dynamics in the canopy proves to be difficult due to the short observational records of the normalized difference vegetation index (NDVI). To explore the linkage between tree growth, NDVI dynamics and largescale atmospheric circulation in the Greater Khingan Mountain, Northeast China, we established a chronology of Larix gmelinii tree ring width at three elevations (870-920 m, 1,100-1,150 m and 1,270-1,320 m) in the northern foothills of the mountain range. We then calculated the correlations between the tree ring chronologies and NDVI and climate factors, and reconstructed the NDVI time series from June to September 1759-2021 in the region based on the middle-elevation tree ring chronology. The results identify the positive effect of temperature (r = 0.56, p < 0.01) and the negative effect of precipitation (r = 0.44, p < 0.01) in the growing season as the main influencing factors of NDVI for the study period (1981-2019). The 11-year moving average of the reconstructed NDVI series reveals two periods of high canopy vigor (1898-1926 and 2009-2013) and three periods of low canopy vigor (1860-1962, 1882-1888 and 1968-1977) in the last 263 years. These periods correspond to drought events recorded in the historical literature. Wavelet analysis shows that the reconstructed sequences exhibited 11-13, 23-25, and 39-42 years period variations. Integrating this with spatial correlation analysis reveals that tree growth in the Mangui region was impacted by the combined effect of the North Pacific Decadal Oscillation and the North Atlantic Multidecadal Oscillation. The results of this paper provide a reference for the study of vegetation change patterns in the northern foothills of the Greater Khingan Mountains. [ABSTRACT FROM AUTHOR]

Larix gmelinii is an important ecological construction tree species in northern China, and its carbon storage and distribution characteristics are of great significance for evaluating the carbon balance and climate effect of forest ecosystems. However, at present, there is a lack of systematic research on the carbon storage of L. gmelinii forests and its change with forest age. In this paper, the biomass and carbon density of L. gmelinii forests at different ages and the distribution of carbon storage in vegetation and soil were analyzed by means of sample plot investigation and model simulation in the northern forest area of Daxing'anling, Inner Mongolia. The influence of forest age on the carbon storage and carbon pool distribution characteristics of L. gmelinii forests and the mechanism of influencing factors were also discussed. Results show that: (1) As forest age increased, the total amount of carbon pools initially increased and then decreased, and the distribution structure of carbon pools showed a trend of transferring from soil to trees. The proportion of soil carbon pools gradually decreased (72.72-51.87%), while the proportion of tree carbon pools gradually increased (23.98-39.33%). The proportion of shrub and grass carbon pools was also relatively stable (0.51-0.53%). (2) Soil carbon pool was affected by the input and output of soil organic matter, soil depth, soil carbon content, and soil bulk density, shrub-grass carbon pool was affected by undergrowth light conditions and soil moisture, litter carbon pool was affected by litter input and output, and the carbon pool of trees was affected by the growth rate and carbon balance of trees. This study provides scientific basis and management suggestions for the carbon storage capacity of L. gmelinii forests and the mitigation of climate change. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To gain an in-depth understanding of the diversity and composition of soil Acidobacteria in five different forest types in typical temperate forest ecosystems and to explore their relationship with soil nutrients. The diversity of soil Acidobacteria was determined by high-throughput sequencing technology. Soil Acidobacteria's alpha-diversity index and soil nutrient content differed significantly among different forest types. β-diversity and the composition of soil Acidobacteria also varied across forest types. Acidobacterial genera, such as Acidobacteria_Gp1, Acidobacteria_Gp4, and Acidobacteria_Gp17, play key roles in different forests. The RDA analyses pointed out that the soil pH, available nitrogen (AN), carbon to nitrogen (C/N) ratio, available phosphorus (AP), total carbon (TC), and total phosphorus (TP) were significant factors affecting soil Acidobacteria in different forest types. In this study, the diversity and composition of soil Acidobacteria under different forest types in a temperate forest ecosystem were analyzed, revealing the complex relationship between them and soil physicochemical properties. These findings not only enhance our understanding of soil microbial ecology but also provide important guidance for ecological conservation and restoration strategies for temperate forest ecosystems. [ABSTRACT FROM AUTHOR]

The soil contains abundant and diverse microorganisms, which interrelate closely with the aboveground vegetation and impact the structure and function of the forest ecosystem. To explore the effect of vegetation diversity on soil microbial functional diversity in taiga forests, we selected significantly different important values of Larix gmelinii as experimental grouping treatments based on plant investigation from fixed plots in Da Xing'anling Mountains. Following that, we collected soil samples and applied the Biolog-ECO microplate method to investigate differences in carbon source utilization, features of functional diversity in soil microorganisms, and factors influencing them in taiga forests. The AWCD decreased as the important value of Larix gmelinii grew, and soil microorganisms preferred carboxylic acids, amino acids, and carbohydrates over polymers, phenolic acids, and amines. The Shannon and McIntosh indexes decreased significantly with the increase of the important value of Larix gmelinii (p < 0.05) and were positively correlated with soil SOC, MBC, C/N, and pH, but negatively with TN, AP, and AN. Redundancy analysis revealed significant effects on soil microbial functional diversity from soil C/N, SOC, AP, MBC, TN, pH, AN, and WC. To sum up, heterogeneous habitats of taiga forests with different important values altered soil microbial functional diversity. [ABSTRACT FROM AUTHOR]

In order to understand the role of microorganisms in litter decomposition and the nutrient cycle in volcanic forest ecosystems, the dominant forest species Larix gmelinii in the volcanic lava plateau of the Wudalianchi volcano was considered as the research object. We analyzed the response of bacterial community structure and diversity to litter decomposition for 1 year, with an in situ decomposition experimental design using litter bags and Illumina MiSeq high-throughput sequencing. The results showed that after 365 days, the litter quality residual rate of Larix gmelinii was 77.57%, and the litter N, P, C:N, C:P, and N:P showed significant differences during the decomposition period (p < 0.05). The phyla Cyanobacteria and the genus unclassified_o_Chloroplast were the most dominant groups in early decomposition (January and April). The phyla Proteobacteria, Actinobacteriota, and Acidobacteriota and the genera Massilia, Pseudomonas, and Sphingomona were higher in July and October. The microbial communities showed extremely significant differences during the decomposition period (p < 0.05), with PCoa, RDA, and litter QRR, C:P, and N as the main factors driving litter bacteria succession. Microbial functional prediction analysis showed that Chloroplasts were the major functional group in January and April. Achemoheterotrophy and aerobic chemoheterotrophy showed a significant decrease as litter decomposition progressed. [ABSTRACT FROM AUTHOR]

To accurately estimate the age of individual tree and to achieve full-cycle sustainable management of natural Larix gmelinii forest in Great Xing' an Mountains of northeastern China, we constructed individual tree age prediction model using stepwise regression and random forest algorithms based on 44 fixed plots data and 280 standard tree cores obtained from the Pangu Forest Farm. We analyzed the influence of stand structure, site conditions, and competition index on the accuracy of model prediction. The model was evaluated by the coefficient of determination (R²), root mean square error (RMSE), and mean absolute error (MAE). The results showed that the random forest model had the highest prediction accuracy when number of decision trees was 1500 and number of node contention variables was 8. The random forest model had better accuracy and prediction ability than the stepwise regression model, with R², RMSE and MAE of 0.5882, 9.9259 a, 8.1155 a. Diameter at breast height was the most important factor affecting age prediction (83.8%), followed by tree height (34.4%), elevation (17.9%), and basal area per hectare (17.5%). The random forest algorithm exhibited better adaptability and modeling effect on constructing a predictive model for individual tree age. This research contributed to improving the accuracy of growth and harvest estimation for L. gmelinii, and could provide a reference for other scientific studies related to tree age estimation in forests. [ABSTRACT FROM AUTHOR]

Leaf senescence is essential for the growth and development of deciduous trees in the next season. Larix gmelinii, a deciduous coniferous tree, exhibits its most distinctive feature by turning yellow in the autumn and eventually shedding its leaves, resulting in significant changes in its appearance during the fall. Lysine acetylation plays an important role in diverse cellular processes; however, limited knowledge is available regarding acetylations in the needle senescence of L. gmelinii. In this study, the proteomics and acetylated modification omics of two phenotypic leaves, yellow and green (senescent and non-senescent) needles, were analyzed before autumn defoliation. In total, 5022 proteins and 4469 unique acetylation sites in 2414 lysine acylated proteins were identified, and this resulted in the discovery of 1335 differentially expressed proteins (DEPs) and 605 differentially expressed acetylated proteins (DAPs) in yellow versus green needles. There are significant differences between the proteome and acetylome; only 269 proteins were found to be DEP and DAP, of which 136 proteins were consistently expressed in both the DEP and DAP, 91 proteins were upregulated, and 45 proteins were down-regulated. The DEPs participate in the metabolism of starch and sucrose, while the DAPs are involved in glycolysis and the tricarboxylic acid cycle. Among them, DEPs underwent significant changes in glycolysis and citric acid cycling. Most of the enzymes involved in glycolysis and the citrate cycle were acetylated. DAPs were down-regulated in glycolysis and up-regulated in the citrate cycle. In all, the results of this study reveal the important role of lysine acetylation in the senescence of L. gmelinii needles and provide a new perspective for understanding the molecular mechanism of leaf senescence and tree seasonal growth.

In order to understand the role of microorganisms in litter decomposition and the nutrient cycle in volcanic forest ecosystems, the dominant forest species Larix gmelinii in the volcanic lava plateau of the Wudalianchi volcano was considered as the research object. We analyzed the response of bacterial community structure and diversity to litter decomposition for 1 year, with an in situ decomposition experimental design using litter bags and Illumina MiSeq high-throughput sequencing. The results showed that after 365 days, the litter quality residual rate of Larix gmelinii was 77.57%, and the litter N, P, C:N, C:P, and N:P showed significant differences during the decomposition period (p < 0.05). The phyla Cyanobacteria and the genus unclassified_o_Chloroplast were the most dominant groups in early decomposition (January and April). The phyla Proteobacteria, Actinobacteriota, and Acidobacteriota and the genera Massilia, Pseudomonas, and Sphingomona were higher in July and October. The microbial communities showed extremely significant differences during the decomposition period (p < 0.05), with PCoa, RDA, and litter QRR, C:P, and N as the main factors driving litter bacteria succession. Microbial functional prediction analysis showed that Chloroplasts were the major functional group in January and April. Achemoheterotrophy and aerobic chemoheterotrophy showed a significant decrease as litter decomposition progressed.

The soil contains abundant and diverse microorganisms, which interrelate closely with the aboveground vegetation and impact the structure and function of the forest ecosystem. To explore the effect of vegetation diversity on soil microbial functional diversity in taiga forests, we selected significantly different important values of Larix gmelinii as experimental grouping treatments based on plant investigation from fixed plots in Da Xing’anling Mountains. Following that, we collected soil samples and applied the Biolog-ECO microplate method to investigate differences in carbon source utilization, features of functional diversity in soil microorganisms, and factors influencing them in taiga forests. The AWCD decreased as the important value of Larix gmelinii grew, and soil microorganisms preferred carboxylic acids, amino acids, and carbohydrates over polymers, phenolic acids, and amines. The Shannon and McIntosh indexes decreased significantly with the increase of the important value of Larix gmelinii (p < 0.05) and were positively correlated with soil SOC, MBC, C/N, and pH, but negatively with TN, AP, and AN. Redundancy analysis revealed significant effects on soil microbial functional diversity from soil C/N, SOC, AP, MBC, TN, pH, AN, and WC. To sum up, heterogeneous habitats of taiga forests with different important values altered soil microbial functional diversity.

To gain an in-depth understanding of the diversity and composition of soil Acidobacteria in five different forest types in typical temperate forest ecosystems and to explore their relationship with soil nutrients. The diversity of soil Acidobacteria was determined by high-throughput sequencing technology. Soil Acidobacteria’s alpha-diversity index and soil nutrient content differed significantly among different forest types. β-diversity and the composition of soil Acidobacteria also varied across forest types. Acidobacterial genera, such as Acidobacteria_Gp1, Acidobacteria_Gp4, and Acidobacteria_Gp17, play key roles in different forests. The RDA analyses pointed out that the soil pH, available nitrogen (AN), carbon to nitrogen (C/N) ratio, available phosphorus (AP), total carbon (TC), and total phosphorus (TP) were significant factors affecting soil Acidobacteria in different forest types. In this study, the diversity and composition of soil Acidobacteria under different forest types in a temperate forest ecosystem were analyzed, revealing the complex relationship between them and soil physicochemical properties. These findings not only enhance our understanding of soil microbial ecology but also provide important guidance for ecological conservation and restoration strategies for temperate forest ecosystems.

As the climate has warmed, alpine treelines have moved to higher altitudes and the responses of tree growth to different climate factors have changed. We collected dendrochronologies of Larix gmelinii at different elevations on the Dabai Mountain, the highest peak in northeastern China's Greater Khingan range, to measure the sensitivity and stability of radial growth over time. We found that the treeline has moved upslope since 1970. From the mid-1980s, radial growth increased in the treeline ecotone but decreased in the subtimberline forest, an example of "growth divergence" under warming conditions: increases in the previous October's maximum temperatures promoted growth at higher altitudes but inhibited it at lower altitudes. The treeline ecotone appears to be more sensitive to climate change, with the effects on tree growth of different climate indicators varying by altitude in linear or U-shaped relationships. As warming continues, the management of boreal forests needs to consider the changing potential for tree growth and carbon sequestration capacity in relation to changing site conditions. [ABSTRACT FROM AUTHOR]

As a crucial link between the aboveground and belowground components of forest ecosystems, soil bacterial communities are extremely sensitive to changes in plant communities and soil conditions. To investigate the impact of the difference of constructive species on soil bacterial communities in taiga forests, we conducted a vegetation survey at the international monitoring plot of the Larix gmelinii forests in the Great Khingan Mountains and calculated the important value of Larix gmelinii to determine experimental groups based on this survey. Subsequently, we collected soil samples for high-throughput sequencing to analyze how the soil bacterial community composition and diversity changed, and which factors affected them. The results showed that taiga forests with different important values of Larix gmelinii had heterogeneous habitats, in which the soil AP content significantly increased, and the SOC, MBC, pH, and C/N content decreased significantly (p < 0.05). A total of 32 phyla, 91 classes, 200 orders, 308 families, 496 genera, and 975 species of soil bacteria were obtained by sequencing. Among them, Proteobacteria, Actinobacteriota, and Acidobacteriota were the dominant phyla, and Mycobacterium was the dominant genus, and the relative abundance of each bacterial group was varied. The beta diversity of soil bacteria showed extremely significant differences (p = 0.001), with SOC, C/N, MBC, AP, TN, pH, AN, and WC being the main influencing factors. Functional prediction analysis showed that chemoheterotrophy and aerobic chemoheterotrophy were the main bacterial functional groups, and the relative abundance of each functional group was significantly different (p < 0.05). Overall, taiga forests with differences in constructive species had heterogeneous habitats, which changed the community composition, beta diversity, and potential functions of soil bacteria. [ABSTRACT FROM AUTHOR]

[Objective ] To explore the differences in growth and understory vegetation between Larix gmelini mixed forest and pure forest. [Method] Taking Larix gmelinii-Pinus strobus L. mixed forest as the research object, we investigated the growth indicators such as tree height, diameter at breast height and crown width, and vegetation indicators such as species, height, abundance and coverage of shrub and herb layers. [Result] The results showed that the DBH, tree height, crown width and individual timber score of Larix gmelinii-Pinus strobus L. mixed forest reached 7.69cm,6.65m,2.02 m and 0.02m³, and the volume of the mixed forest reached 29.63 m³/hm², which was 2.00 times, 1.58 times, 1.19 times, 6.67 times and 4.03 times of that of Larix gmelinii-Pinus strobus L. mixed forest, and the shape and quality index of Larix gmelinii in the mixed forest was better than that of the pure Larix gmelinü forest. In terms of quantity, the total number of species and the number of herbs were slightly higher in the pure Larix gmelinii forest than in Larix gmelinii-Pinus strobus L. mixed forest, while the opposite was true for shrubs. From the perspective of Diversity index, except for the herb richness index, other Diversity index showed that Larix gmelinii-Pinus strobus L. mixed forest was superior to Larix gmelinii pure forest. [Conclusion] Larix gmelinii mixed forest was superior to pure forest in growth and understory vegetation. In the future development of Larix gmelinii plantation, more Larix gmelinii mixed forest should be built. [ABSTRACT FROM AUTHOR]

The Boreal forest has been disturbed by forest fire in different degrees for a long time, which plays a key role in nutrient cycling in forest soil. In order to explore the soil nutrient characteristics after forest fire under different site conditions, the soil of burned area in Huzhong forestry bureau of Greater Khingan Mountains was selected as the research object, soil samples were collected from four plots with similar forest age, slope location and different site conditions. Main chemical properties of soil pH, soil total carbon (TC), soil total nitrogen (TN), soil total phosphorus (TP), soil organic carbon (SOC) as well as two soil enzyme activities (cellulase (CBH) and β－glucosidase (βG) ) in different areas (interior area, edge area, and unburned area) were measured and analyzed. The result showed that the Larix gmelinii－Betula platyphylla mixed forest had the most abundant soil nutrient conditions, and the soil nutrient content after a fire was still better than the other three sample sites. Compared to the unburned area, TC and SOC in the edge area of each forest type decreased significantly, the activity of soil enzyme CBH and βG showed a significant upward trend (P＜0.05) . Compared with the edge area, TC, TN and SOC were significantly decreased (P＜ 0. 05) in the interior area of Larix gmelinii－Pinus pumila forest mixed forest dominated by Larix gmelinii, while the contents of TC, TN and SOC were significantly increased (P＜0. 05) in the Larix gmelinii－Betula platyphylla mixed forest, and the activities of CBH and βG in the interior area were significantly decreased compared with the edge area, while the enzyme activity in the interior area of the Larix gmelinii-Betula platyphylla mixed forest was significantly higher than that in the edge area (P<0. 05). Fire disturbance had no significant effect on soil pH in these forest types (P>0. 05). Fisher discriminant analysis showed that the overall differentiation of sample distribution was worse when the burned area was taken as the dependent variable than when Pinus pumila-Larix gmelinii forest mixed forest dominated by pinus,Pinus pumila-Larix gmelinii forest mixed forest dominated by larch,Carex-Larix gmelinii forest,Larix gmelinii-Betula platyphylla mixed forest was taken as the dependent variable. In conclusion, forest fire significantly changed the soil nutrient contents and soil enzyme activities in four forest types, but it had less effect on pH. The difference in soil nutrients between forest types was greater than that in different burned areas. At the initial stage after fires, the authorities should take different plans for these forests to promote restoration. This study can provide theoretical support for evaluating the effect of fire disturbance on soil nutrient change in the cold temperate zone Larix Xingan forest, and provide reference for the formulation of forest restoration plan after fire in the northern coniferous forest. [ABSTRACT FROM AUTHOR]

To explore the effects of different light intensities on the physiological growth of Larix gmelinii seedlings, this study assessed three height grades of L. gmelinii seedlings (≤0.5-1, 0.5-1, and 1-3 m) under the following treatments: full light (control), 65% NS (natural sunshine), 35% NS, and 10% NS. After treatment, photosynthetic pigment content, light response curve, CO2 response curve, Chlorophyll Fluorescence and Diurnal Variations in Photosynthesis were assessed. Shading increased the photosynthetic pigment contents of L. gmelinii seedlings and young trees and played a positive role in the adaptation of L. gmelinii seedlings and young trees to low-light environments. The maximum net photosynthetic rate, maximum carboxylation rate, maximum photoelectron transmission rate, and utilization efficiency of acetone phosphate of L. gmelinii (1-3 m) considerably increased under the 65% NS treatment, showed the strongest photoinhibition resistance and a high proportion of the open PSII reaction center. The best shade treatment for young L. gmelinii trees at 1-3 m was 65% NS, which indicates that this treatment can improve the photosynthetic capacity of young L. gmelinii trees. However, for the growth of smaller L. gmelinii seedlings, an environment with greater light intensity is more suitable. [ABSTRACT FROM AUTHOR]

Large trees dominate stand-level biomass but their growth suffers more from droughts, while sheltering small trees during droughts. Under a warmer and drier climate, whether the growth decline of large trees could be compensated by prompted small trees’ growth remains unknown. Based on the Standardized Precipitation Evapotranspiration Index (SPEI) series, drought characteristics were determined, and two drought events were selected. We reconstructed historical diameters at breast height (DBH) and the aboveground biomass of Larix gmelinii through tree ring data allometric equations. To clarify the difference in the responses of tree size to drought, we calculated resistance, recovery, and resilience in each diameter class. We used a growth dominance coefficient (GDC) to exhibit the contributions of different-sized individuals to stand growth and demonstrated the growth dynamics of both the individual and stand level. The results proved that large trees were more vulnerable to local droughts, the resilience of larch had a negative relationship with the DBH (p < 0.05), and small trees could recover to even exceed their pre-drought growth level. Most plots had a negative GDC and small trees contributed more to stand growth compared with their size, but their AGB growth was far less than that of large trees, which made it difficult to compensate for stand growth decline. Our results indicate that tree resilience has a negative relationship with their pre-drought sizes, as large trees in the stand fail to regain their growth level before drought. Even with a larger relative contribution and higher resilience, small trees cannot cover deficits in large trees’ growth. Under more frequent droughts, the total aboveground biomass growth of larches would decline.

Ecmycorrhizal fungi (ECMF) can improve the resistance of host plants to external environmental stress and promote the growth of plants. In order to understand the effects of ECMF on the growth and soil remediation of Larix gmelinii under heavy metal copper (Cu) stress, pot experiment was conducted to inoculate L. gmelinii seedlings with Boletus edulis (Be), Gomphidius rutulus (Gr) and Be+Gr. The mechanism of growth, root development, nutrient elements and copper absorption and distribution of different mycorrhizal fungi under heavy metal copper (0, 40, 80, 160, 320 mg / kg) stress was studied. The results showed that both ECMFs could form a good symbiotic relationship with L. gmelinii, and copper concentration had a significant effect on the infection rate of root ectomycorrhizal fungi. Under different Cu concentrations, inoculation of ECMF can significantly promote the growth of seedlings, increase the biomass of roots and plants, enhance the absorption of nutrient elements and heavy metal Cu, and change the distribution pattern of aboveground and underground parts with the increase of copper stress concentration. With the increase of Cu application concentration, the aboveground and underground biomass and the absorption of N, P and K nutrients of each inoculation treatment plant showed a trend of first increasing and then decreasing, and the copper accumulation increased, the mycorrhizal structure reduced the migration of Cu to the aboveground part by absorbing and holding copper, thus alleviating the heavy metal Cu stress. Compared with single inoculation, mixed inoculation of Be+Gr had the most significant effect on the copper stress resistance of L. gmelinii. Therefore, ectomycorrhizal fungi inoculated with L. gmelinii have certain application value in ecological remediation of Cu contaminated soil. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using a static chamber-gas chromatography method, we investigate the characteristics of soil CO2, CH4, and N2O fluxes and their relationships with environmental factors during the growing season in four typical Larix gmelinii forests (moss–Larix gmelinii forest, Ledum palustre–Larix gmelinii forest, herbage–Larix gmelinii forest, and Rhododendron dauricum–Larix gmelinii forest) in the Greater Khingan Mountains. Our results show that all four forest types are sources of CO2 emissions, with similar average emission fluxes (146.71 mg·m−2 h−1–211.81 mg·m−2 h−1) and no significant differences. The soil in the moss–Larix gmelinii forest emitted CH4 (43.78 μg·m−2 h−1), while all other forest types acted as CH4 sinks (−56.02 μg·m−2 h−1–−28.07 μg·m−2 h−1). Although all forest types showed N2O uptake at the beginning of the growing season, the N2O fluxes (4.03 μg·m−2 h−1–5.74 μg·m−2 h−1) did not differ significantly among the four forest types for the entire growing season, and all acted as sources of N2O emissions. The fluxes of CO2, CH4, and N2O were significantly correlated with soil temperature and soil pH for all four forest types. Multiple regression analysis shows that considering the interactive effects of soil temperature and moisture could better explain the changes in greenhouse gas emissions among different forest types. The average Q10 value (8.81) of the moss–Larix gmelinii forest is significantly higher than that of the other three forest types (3.16–3.54) (p < 0.05), indicating that the soil respiration in this forest type is more sensitive to temperature changes. [ABSTRACT FROM AUTHOR]

Larix gmelinii (Rupr.) Kuzen is a major tree species with high economic and ecological value in the Greater Khingan Mountains coniferous forest of Northeast China. Reconstructing the priority Conservation Area of Larix gmelinii under Climate could provide a scientific basis for its germplasm conservation and management. The present study used ensemble and Marxan model simulations to predict species distribution areas and delineate priority conservation areas for Larix gmelinii in relation to productivity characteristics, understory plant diversity characteristics, and climate change impacts. The study revealed that the Greater Khingan Mountains and the Xiaoxing'an Mountains, with an area of approximately 300 974.2 km², were the most suitable for L. gmelinii. The stand productivity of L. gmelinii in the most suitable area was significantly higher than that in the less suitable and marginally suitable areas, but understory plant diversity was not dominant. The increase in temperature under future climate change scenarios will reduce the potential distribution and area under L. gmelinii; the species will migrate to higher latitudes of the Greater Khingan Mountains, while the degree of niche migration will gradually increase. Under the 2090s-SSP585 climate scenario, the most suitable area for L. gmelinii will completely disappear, and the climate model niche will be completely separated. Therefore, the protected area of L. gmelinii was demarcated with a target of the productivity characteristics, understory plant diversity characteristics and climate change sensitive area, and the current key protected area was 8.38 × 104 km2. Overall, the study's findings will lay a foundation for the protection and rational development and utilization of cold temperate coniferous forests dominated by L. gmelinii in the northern forested region of the Greater Khingan Mountains. [ABSTRACT FROM AUTHOR]

In this study, the effects of climatic factors on the radial growth of trees in the Greater Khingan Mountains, under different competition intensities, were studied using dendrochronology and a competition index. The results showed that under different competition intensities, the radial growth of the trees was affected by climatic factors, under different circumstances. Under low competition intensities, the tree-ring width index was negatively correlated with the monthly average maximum temperature in March and positively correlated with the precipitation in April of the current year. Under moderate competition intensities, the tree-ring width index was negatively correlated with the monthly average temperature and monthly average maximum temperature in March and positively correlated with the precipitation in April and the monthly average minimum temperature in May of the current year. Under high competition intensities, the monthly average minimum temperature in May of the current year was significant. A multiple-stepwise regression method was used to simulate the relationship between the tree-ring width index and climate factors; a model was established to predict whether the radial growth of Larix gmelinii would be inhibited by increasing the annual average temperature. [ABSTRACT FROM AUTHOR]

Copyright of Mycosystema is the property of Mycosystema Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil fungi play an indispensable role in forest ecosystems by participating in energy flow, material circulation, and assisting plant growth and development. Larix gmelinii is the dominant tree species in the greater Khingan Mountains, which is the only cold temperate coniferous forest in China. Understanding the variations in underground fungi will help us master the situation of L. gmelinii above ground. We collected soil samples from three seasons and analyzed the differences in soil fungal community structure using high-throughput sequencing technology to study the seasonal changes in soil fungal community structure in L. gmelinii forests. We found that the Shannon and Chao1 diversity in autumn was significantly lower than in spring and summer. The community composition and functional guild varied significantly between seasons. Furthermore, we showed that ectomycorrhizal fungi dominated the functional guilds. The relative abundance of ectomycorrhizal fungi increased dramatically from summer to autumn and was significantly negatively correlated with temperature and precipitation. Temperature and precipitation positively affect the alpha diversity of fungi significantly. In addition, pH was negatively correlated with the Chao1 diversity. Temperature and precipitation significantly affected several dominant genera and functional guilds. Among the soil physicochemical properties, several dominant genera were affected by pH, and the remaining individual genera and functional guilds were significantly correlated with total nitrogen, available phosphorus, soil organic carbon, or cation exchange capacity. For the composition of total fungal community, temperature and precipitation, as well as soil physicochemical properties except AP, significantly drove the variation in community composition. [ABSTRACT FROM AUTHOR]

The dendroecology of larch (Larix gmelinii Rupr.) in the world’s northernmost forest provided insight into the complex relationship of tree growth, forest stand establishment, and changing eco-climatic factors. The Ary-Mas forest in the northern Siberia (72° + NL) is an ecological island, surrounded by tundra. We hypothesized that the environmental constraints that limit larch growth in this harsh habitat include soil moisture and winter winds as well as low air temperature. We constructed and analyzed the larch growth index (GI) chronology from the eighteenth century until 2019. We found that the larch GI depended on the air temperature, soil moisture anomalies, and winter wind speed, and that dependence was significantly different before and after the 2000s. Larch GI responded to the onset of climatic warming in the 1970s by a minor GI increase followed by a GI decrease until the end of 1990. Increased air temperature early in the growing season favored increased GI, whereas elevated winter wind speed negatively influenced larch growth. After warming in the 2000s, the length of the growing season increased by 15 days, and larch GI was sensitive to air temperature both early and late in the growing season. The adverse influence of winter winds has gradually decreased since the 1970s, becoming a minor factor in the 2000s. Soil moisture in “wet, cold soils” negatively influenced larch growth. Meanwhile, decreased soil moisture in the northern lowlands favored increased larch growth. We found that larch growth increases were strongly correlated with GPP and NPP (gross and net primary productivity) within the Ary-Mas site and for the central Siberian Arctic. We infer that this Arctic region continues to be a carbon sink. [ABSTRACT FROM AUTHOR]

Background: Fire-caused tree mortality and spatial pattern are crucial for evaluating forest dynamics and developing management prescriptions. Aims: We investigated direct fire effects on spatial distribution and mortality of Dahurian larch (Larix gmelinii Rupr.) and assessed the Ryan and Amman (R–A) model performance and the importance of immediate mortality predictors. Methods: We analysed spatial patterns of fire-killed and surviving trees of three size classes in plots that burned at low- to high-severity using pair-correlation functions and tree mortality with the R–A model and generalised linear mixed models. Key results: The mixed-severity fire caused strong density-dependent mortality and more aggregated surviving tree patterns at short distances. The R–A model generally performed acceptably, and crown scorch and bole char height were critical predictors determining post-fire tree mortality. Conclusions: Fire-caused tree mortality and spatial patterns are controlled primarily by spatial variation in tree size and biological and structural characteristics. The prediction biases of the R–A model arose primarily from the intrinsic traits of Dahurian larch and the imbalanced dataset. Fine-scale neighbourhood density might be a fundamental priority for fire management and restoration. Implications: This study could possibly improve mechanistic understanding of spatial pattern development and tree mortality in similar fire-prone conifer forests. A larch-dominated forest exhibited density-dependent post-fire mortality patterns at short distances and increased aggregation among surviving trees post-fire. A widely used USA tree mortality model performed acceptably for this species. This study could potentially inform management strategies for conifer forests with similar structures and fire regimes. [ABSTRACT FROM AUTHOR]

The stability and dynamics of soil organic carbon (SOC) pools in forest soils are crucial for assessing and predicting the effectiveness of forest carbon sequestration. Various factors such as soil depth, nutrients availability, crustal elements, pH, and stand characteristics (tree type, tree age) influence the stability of SOC pools. To better understand SOC stability of cold temperate forest soil, soil samples were collected from 0–10 cm, 10–20 cm, 20–40 cm, and 40–60 cm depths in a Larix gmelinii forest. Then, the distribution characteristics of SOC pools under different protection mechanisms and their influencing factors were examined. Our results showed that the unprotected SOC pool was the highest, while the physical–chemical protected SOC pool was the lowest. Total organic carbon (TOC) had a linear positive relationship with unprotected and physical-protected SOC pools, and a logarithmic positive relationship with physical–chemical protected and chemical-protected SOC pools. Soil depth was the predominant factor affecting the SOC pools of each protection mechanism. The physical–chemical protected SOC pool significantly differed from forest types and forest ages, and the chemical-protected SOC pool was associated with the synergistic effects of forest age and type. Furthermore, soil moisture and acidity, and the crustal elements may play prominent role in the variation of SOC pools in the Larix gmelinii forests. Our findings suggested that the silt- and clay-associated SOC pools in the Larix gmelinii forest soils had approached or achieved saturation, while more organic C was fixed in the relatively active unprotected SOC pool. This unprotected pool was more sensitive to ecosystem change, indicating its importance in assessing forest carbon sequestration. Our study provided insights into the active and dynamic SOC pools in forest soils and their responses to different environmental factors. These findings can be utilized to accurately assess the carbon sink potential of cold temperate forest soils and inform the management of forest ecosystems.

Nitrogen (N) serves as the primary limiting nutrient for plant growth in the majority of terrestrial ecosystems. However, the effect of long-term N addition on root N acquisition, in particular the seasonal dynamics, is still not well understood. In a 19-year N addition experiment on plantations of ectomycorrhizal tree species Larix gmelinii (larch) and arbuscular mycorrhizal tree species Fraxinus mandshurica (ash), we determined root morphological, chemical and mycorrhizal traits, as well as soil properties. Concurrently, we used a field isotopic hydroponic method to measure root uptake rates of NH 4 +, NO 3 -, and glycine in the early, mid and late growing season. Following N addition, mycorrhizal colonization rates in both species were reduced in early and late growing season. Root tissue density was reduced but specific root length and area were increased in ash under N addition across growing seasons, however, no significant differences in these traits were found in larch. Under N addition, both species showed lower uptake rates of all N forms and the total N than the controls throughout the growing season, except for the glycine-uptake of larch in early growing season. N addition did not modify the N-uptake preference in both species, but the contributions of specific N form to the total N varied with seasons. Collectively, referring to the framework of "root economics space", these two species particularly ash showed greater reliance on the "do-it-yourself" strategy for N acquisition under long-term N addition, although the degree of which somewhat varied with season. Seasonal dynamics in root N-uptake rates of ash were mainly related to soil temperature and moisture, rather than soil N properties, showing less direct impact of N addition. Our findings provide deep insights into the effect of N deposition on root N acquisition strategy and related functions of forest ecosystem. [Display omitted] • Effects of 19-year nitrogen (N) addition on root N-uptake strategy were determined. • Field isotope hydroponic method was used to measure N-uptake rate in ash and larch. • N addition decreased root N-uptake rate rather than preference in both species. • N acquisition shifted to a 'DIY' strategy under N addition, particularly in ash. • Seasonal dynamics of N-uptake rates were mainly related to environmental factors. [ABSTRACT FROM AUTHOR]

As a crucial link between the aboveground and belowground components of forest ecosystems, soil bacterial communities are extremely sensitive to changes in plant communities and soil conditions. To investigate the impact of the difference of constructive species on soil bacterial communities in taiga forests, we conducted a vegetation survey at the international monitoring plot of the Larix gmelinii forests in the Great Khingan Mountains and calculated the important value of Larix gmelinii to determine experimental groups based on this survey. Subsequently, we collected soil samples for high-throughput sequencing to analyze how the soil bacterial community composition and diversity changed, and which factors affected them. The results showed that taiga forests with different important values of Larix gmelinii had heterogeneous habitats, in which the soil AP content significantly increased, and the SOC, MBC, pH, and C/N content decreased significantly (p < 0.05). A total of 32 phyla, 91 classes, 200 orders, 308 families, 496 genera, and 975 species of soil bacteria were obtained by sequencing. Among them, Proteobacteria, Actinobacteriota, and Acidobacteriota were the dominant phyla, and Mycobacterium was the dominant genus, and the relative abundance of each bacterial group was varied. The beta diversity of soil bacteria showed extremely significant differences (p = 0.001), with SOC, C/N, MBC, AP, TN, pH, AN, and WC being the main influencing factors. Functional prediction analysis showed that chemoheterotrophy and aerobic chemoheterotrophy were the main bacterial functional groups, and the relative abundance of each functional group was significantly different (p < 0.05). Overall, taiga forests with differences in constructive species had heterogeneous habitats, which changed the community composition, beta diversity, and potential functions of soil bacteria.

As the climate has warmed, alpine treelines have moved to higher altitudes and the responses of tree growth to different climate factors have changed. We collected dendrochronologies of Larix gmelinii at different elevations on the Dabai Mountain, the highest peak in northeastern China’s Greater Khingan range, to measure the sensitivity and stability of radial growth over time. We found that the treeline has moved upslope since 1970. From the mid-1980s, radial growth increased in the treeline ecotone but decreased in the subtimberline forest, an example of “growth divergence” under warming conditions: increases in the previous October’s maximum temperatures promoted growth at higher altitudes but inhibited it at lower altitudes. The treeline ecotone appears to be more sensitive to climate change, with the effects on tree growth of different climate indicators varying by altitude in linear or U-shaped relationships. As warming continues, the management of boreal forests needs to consider the changing potential for tree growth and carbon sequestration capacity in relation to changing site conditions.

The altitudinal patterns of soil fungi have attracted considerable attention; however, few studies have investigated the diversity and community assembly of fungal functional guilds along an altitudinal gradient. Here, we explored ectomycorrhizal (EcM) and saprotrophic (SAP) fungal diversity and community assembly along a 470 m vertical gradient (ranging from 830 to 1300 m) on Oakley Mountain, sampling bulk soils in the 0–10 cm and 10–20 cm soil layers of Larix gmelinii-dominated forests. Illumina MiSeq sequencing of the ITS genes was employed to explore the fungal community composition and diversity. The relative abundance of EcM and SAP fungi showed a divergent pattern along an altitudinal gradient, while we observed a consistent altitudinal tendency for EcM and SAP fungal diversity and community assembly. The diversity of both fungal guilds increased with increasing altitude. Altitude and soil moisture were the key factors affecting the community composition of both fungal guilds. In addition, the plant community composition significantly affected the EcM fungal community composition, whereas the dissolved organic nitrogen and ammonium nitrogen contents were the driving factors of SAP fungal community. Despite the effects of vegetation and soil factors, EcM and SAP fungal communities were mainly governed by stochastic processes (especially drift) at different altitudes and soil depths. These results shed new light on the ecology of different fungal functional guilds along an altitudinal gradient, which will provide a deeper understanding of the biogeography of soil fungi. [ABSTRACT FROM AUTHOR]

Simple Summary: Climate change shown to have a significant impact on the forest ecosystem due to increased and more frequent occurrence of extreme drought. However, in order to successfully adjust to the xeric environments, plants can usually adopt a variety of adaptation strategies. Here, we investigated the morpho-anatomical traits and biomass allocation patterns as acclimation mechanisms in drought conditions. We found that the interrelation between leaf morphological and anatomical traits were equally affected by drought conditions across all species. This suggests that there is no convincing evidence to classify taxa based on drought resistance vs. drought tolerance. However, based on the biomass allocation pattern, we found that P. koraiensis and F. mandshurica had the higher RMF and total PB, but lower LFM, suggesting higher drought tolerance than those of the other species. Therefore, our dataset revealed some easily measurable traits, such as LMF, RMF, and PB, which demonstrated the seedling's ability to cope with drought and which could be utilized to choose drought-tolerant species for reforestation in the temperate forest. Drought is a critical and increasingly common abiotic factor that has impacts on plant structures and functioning and is a challenge for the successful management of forest ecosystems. Here, we test the shifts in leaf morpho-anatomical or hydraulic traits and plant growth above ground caused by drought. A factorial experiment was conducted with two gymnosperms (Larix gmelinii and Pinus koraiensis) and two angiosperms (Fraxinus mandshurica and Tilia amurensis), tree species grown under three varying drought intensities in NE China. Considering all the species studied, the plant height (PH), root collar diameter (RCD), and plant biomass (PB) were significantly decreased by drought. The leaf thickness (LT) increased, while the leaf area (LA) decreased with drought intensity. In the gymnosperms, the mesophyll thickness (MT) increased, and the resin duct decreased, while in the angiosperms the palisade mesophyll thickness (PMT), the spongy mesophyll thickness (SMT), and the abaxial (ABE) and adaxial epidermis (ADE) thickness were increased by drought. The correlation analysis revealed that P. koraiensis and F. mandshurica had the higher RMF and total plant biomass, but the least LMF, suggesting drought tolerance. In contrast, the L. gmelinii had the least RMF and higher LMF, suggesting vulnerability to drought. Similarly, T. amurensis had the higher leaf size, which increased the evaporative demand and depleted the soil water quickly relative to the other species. The interrelation among the morpho-anatomical leaf traits was equally affected by drought across all the studied species, suggesting that there is no clear evidence to differentiate the taxa based on drought resistance vs. drought tolerance. Thus, we have identified some easily measurable traits (i.e., LMF, RMF, and PB) which evidenced the seedling's ability to cope with drought and which therefore could be used as proxies in the selection of drought tolerant species for reforestation in the temperate forest. [ABSTRACT FROM AUTHOR]

Wildfire is a widespread phenomenon on the earth that has affected most ecosystems and is responsible for enormous economic and environmental damage. The Greater Khingan Mountains, the south boundary of the boreal forest, are a fire-prone area. However, the effect of fire disturbance on tree growth in response to climate warming is unknown. To predict the future dynamics of boreal forests after fire disturbance and their feedback on climate change, we analyzed Larix gmelinii growth-climate relationships in burned areas at six sites. The result showed a significant decline in the growth of burned trees in all locations except CY1 during the fire years. There was a growth release 3–5 years after the fire disturbance. The result of growth-climate relationships found that the response of CY1 and GH burned and unburned trees to mean temperature changed from a positive to a negative correlation before and after the fire year. Changes in tree growth response to PDSI were significant for both burned and unburned trees, suggesting that this change in response is related to fire disturbance and influenced by climate warming and drying in recent decades. The resistance of larch to fire showed that in the three years before and after the fire year, there was a significant reduction in the growth of burned larch, except for CY1. Our findings suggested that burned and unburned larch respond differently to climate change. Wildfires change the relationship between the radial growth of trees and climate factors. It may also alter the structural composition and biodiversity of boreal forests.

Using a static chamber-gas chromatography method, we investigate the characteristics of soil CO2, CH4, and N2O fluxes and their relationships with environmental factors during the growing season in four typical Larix gmelinii forests (moss–Larix gmelinii forest, Ledum palustre–Larix gmelinii forest, herbage–Larix gmelinii forest, and Rhododendron dauricum–Larix gmelinii forest) in the Greater Khingan Mountains. Our results show that all four forest types are sources of CO2 emissions, with similar average emission fluxes (146.71 mg·m−2 h−1–211.81 mg·m−2 h−1) and no significant differences. The soil in the moss–Larix gmelinii forest emitted CH4 (43.78 μg·m−2 h−1), while all other forest types acted as CH4 sinks (−56.02 μg·m−2 h−1–−28.07 μg·m−2 h−1). Although all forest types showed N2O uptake at the beginning of the growing season, the N2O fluxes (4.03 μg·m−2 h−1–5.74 μg·m−2 h−1) did not differ significantly among the four forest types for the entire growing season, and all acted as sources of N2O emissions. The fluxes of CO2, CH4, and N2O were significantly correlated with soil temperature and soil pH for all four forest types. Multiple regression analysis shows that considering the interactive effects of soil temperature and moisture could better explain the changes in greenhouse gas emissions among different forest types. The average Q10 value (8.81) of the moss–Larix gmelinii forest is significantly higher than that of the other three forest types (3.16–3.54) (p < 0.05), indicating that the soil respiration in this forest type is more sensitive to temperature changes.

In order to further understand the effects of forest tree species and habitats on soil macroinvertebrates community, and provide reference for sustainable management of plantations, this paper took Populus simonii × P. nigra and Larix gmelinii plantations as the research objects, and studied the characteristics of soil macroinvertebrate community in different habitats by setting quadrats under different forest gaps and canopies. The results showed: ① Formicidae, Enchytracidae and Lumbricida were common group in two stands, and the individuals and groups were higher in Populus simonii × P. nigra plantation. The individuals and groups in the medium and large gaps were higher than that in the small gap in the two stands. ② The dominant soil macroinvertebrates were omnivorous in Populus simonii × P. nigra plantations. With the decrease of gap area, the proportion of omnivorous decreases. Larix gmelinii was dominated by scavengers, and the proportion of scavengers increased gradually with the decrease of gap area. ③ The vertical distribution of soil invertebrates was affected by gap size, and the number of individuals and groups in the litter layer was lower than that in the soil layer. ④ Stand types had no significant effect on the diversity of soil macroinvertebrate community (P>0. 05). The size of forest gap had a significant effect on the diversity of soil macroinvertebrate community(P<0. 05). The diversity of Populus simonii × P. nigra plantation gap was low, and the diversity of large gaps in Larix gmelinii plantation was high. In conclusion the effect of stand type on macroinvertebrates was not obvious, but the effect of gap disturbance on macroinvertebrates was greater. The small to medium gaps of Populus simonii × P. nigra plantation were favorable for the survival of soil invertebrates, while the medium to large gaps of Larix gmelinii plantation had richer soil invertebrate communities and higher diversity [ABSTRACT FROM AUTHOR]

The biodiversity of tundra areas in northern high latitudes is threatened by invasion of forests under global warming. However, poorly understood nonlinear responses of the treeline ecotone mean the timing and extent of tundra losses are unclear, but policymakers need such information to optimize conservation efforts. Our individual-based model LAVESI, developed for the Siberian tundra-taiga ecotone, can help improve our understanding. Consequently, we simulated treeline migration trajectories until the end of the millennium, causing a loss of tundra area when advancing north. Our simulations reveal that the treeline follows climate warming with a severe, century-long time lag, which is overcompensated by infilling of stands in the long run even when temperatures cool again. Our simulations reveal that only under ambitious mitigation strategies (relative concentration pathway 2.6) will ∼30% of original tundra areas remain in the north but separated into two disjunct refugia.

Fire behavior prediction requires precise models of fuel moisture content that are both accurate and suitable be assessed by evaluating fire spread, fireline intensity and fuel consumption and use for operational applications. In fire behavior prediction in Liaoning Province, where locates at Northeastern China, because of their increasing frequency of forest fire events are driving the need for fuel moisture predictions that go beyond what is possible with fuel moisture models currently in use. To establish accurate fuel moisture models, hourly measurements were taken of twigs moisture content of Larch (Larix gmelinii) forest stands and under different slope conditions. Conditions in relation to weather conditions, namely air temperature and relative humidity. All twig fuels were categorized according to diameter classes and degree of decay. Nelson and Simard methods which employed the function of equilibrium moisture content and timelag concept, along with direct regression methods, which were directly from fuel moisture and weather observation data was also used during our research. The results indicated that i) the Nelson method correctly predicted hourly twigs moisture content in forest stands, followed by Simard method, and direct regression method was the least; ii) the effect of Simard method by extrapolation was the most satisfied for its minor deviations on calculations of extrapolation matrix, while direct regression method is the least satisfied predication model; iii) different methods generated from forest under diameter classes, decay degree and slope conditions differently, generally, the effect of light deposited and fine fuels were better, rather than slope positions, but the coefficient of determinations of these models predicted by three methods were not obvious. Overall, Simard was more robust and simple estimation, and similar accuracy to Nelson method, therefore is recommended for predicting fuel moisture, and our research results will be in valuable for fire management planning and modeling in this region. [ABSTRACT FROM AUTHOR]

Spot fire increase the difficulty of fire-fighting and threaten public safety, and therefore it is important to study ignition probabilities of fuel bed by different firebrands, in order to understand ignition mechanisms and analyze the formation of spot fires. This will provide an important basis for further study to improve the fire-fighting efficiency and reduce casualties. In this study, the ignition probabilities of larch (Larix gmelinii) fuel beds with different moisture levels and packing ratios by diffreent firebrands, including cones and twigs of different sizes, was investigated. Ignition experiments were conducted at different wind speeds generated by fans. The results show that, regardless of moisture content and packing ratio, ignition probability is zero when there is no wind. Both moisture content and wind speed significantly influence ignition probability, while packing ratio has almost no effect. The maximum moisture content at which firebrand ignition occurred was 50%, and ignition probability increased with wind speed and decreased with moisture content. Cones have the highest ignition probability, followed by large twigs and by small twigs. Ignition probability is also affected by firebrand shapes and sizes that determine their potential heat and contact area to the fuel bed. Two empirical models were established to link ignition probability with fuel properties and wind speed. This study will help clarify the mechanism of spot ignition and reduce corresponding losses. [ABSTRACT FROM AUTHOR]

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to reasonably evaluate the level of fire danger in Larix gmelinii logging slash and explore the interaction between fire danger factors, and provide the theoretical support for the fire prevention of Larix gmelinii plantation, in this paper, the cross-impact method and Markov prediction model were used to analyze the 17 factors affecting the fire, and the correction probability of each factor was calculated. Through the Larix gmelimii of Xinlin District in Daxing’an mountains case analysis, it can be seen that after the cross impact, the possibility of fire caused by the temperature, relative humidity, precipitation, fuel distribution pattern and oil content of cutting roots were on the rise. The probability of fire caused by the gradient, fuel reserves, cutting height, fire safety awareness, and fire patrol and supervision showed a downward trend in the area. The improved cross-impact analysis method can be applied to the analysis of fire danger factors in Larix gmelinii logging slash, which can correctly analyze the interaction between the factors, and provide a new idea and direction for the fire risk decision of Larix gmelinii plantation. [ABSTRACT FROM AUTHOR]

Purpose: Soil properties play key roles in ecosystem recovery at the landscape scale and are regulated by a complex interplay between abiotic and biotic factors. Our study aimed to identify the potential drivers of post-fire changes in mineral soil in the larch forest of southeastern Siberia. Methods: We established a 28-year fire chronosequence with 80 sites over a small region of the Greater Khingan Range. At each site, we measured topographic factors, arboreal variables, and ten physical and chemical attributes of surface mineral soils. We used the hierarchical clustering analysis, distance-based redundancy analysis, variation partitioning analysis, Random Forest analysis, and structural equation modeling to disentangle the drivers for the coupled and decoupled patterns in soil properties. Results: The results showed that time since fire is an ecological predictor that cannot be completely discarded for the soil property prediction model. Wildfires altered the effects of topography and arbors on soil properties. Compared with the unburned area, the soil properties of the burned area were associated more with explanatory variables. Here, altitude was a powerful topographic factor that positively correlated with soil properties, whereas slope position, gradient, and aspect had more negative and less positive effects on soil fertility and exhibited similar patterns, of which slope position and gradient exerted stronger influences than aspect. The importance ranking of average tree size was not significantly changed by fires though its relationship with the soil was obviously changed. Conclusions: In boreal larch forest, wildfires enhance the impact of topography on soil properties while decreasing the impact of arbors on soil properties. Although the arbors are not as critical as topography to the change of soil properties in a few decades after fire, the importance of arbors tends to gradually increase over many years. Consequently, wildfires can cause an on-going shift in the importance and the relative importance of topography and arbors on soil properties in boreal larch forest. [ABSTRACT FROM AUTHOR]

Purpose: To examine and understand mechanisms of hydrological functions and water transport of Larix gmelinii ecosystems, we quantified water consumption (ET), including soil evaporation (E) and vegetation transpiration (T), and the role of environmental factors. Methods: Stable isotope technology was utilized to make high-frequency in situ observations on the oxygen isotope composition (δ18O) of water vapor from six vertical heights (0.1–40 m above ground) in the cold-temperate Larix gmelinii forests in Northeast China. The dynamics of δ18O and its responses to environmental factors were detected during the water consumption process. One-way analysis of variance, independent-samples t test, and path analysis were used in data analysis. Results: The oxygen isotope composition of water vapor decreased with increasing vertical height. Contribution of T to ET varied between 79 and 96%. Values of δ18O in water vapor produced by E (δ18OE) corresponded most closely to water content at 10-cm soil depth (SWC10), while those produced by T (δ18OT) were associated with different environmental factors: air temperature (Ta) for the shrub-based stand, relative humidity (RH) for the herb-based stand, and temperature at 5-cm soil depth (Ts5) for the moss-based stand. Solar radiation (SR) was the dominant factor controlling the δ18O of water vapor produced by ET (δ18OET). Conclusion: Transpiration is the primary means of ecosystem water loss in Larix gmelinii forests. Overall, water loss from T of shrub-based Larix gmelinii stand is greater than those of herb-based and moss-based stands. Meteorological and soil factors mutually affect ecosystem water loss to atmosphere. [ABSTRACT FROM AUTHOR]

Abstract Background Establishing mixed plantations is an effective way to improve soil fertility and increase forest productivity. Arbuscular mycorrhizal (AM) fungi are obligate symbiotic fungi that can promote mineral nutrient absorption and regulate intraspecific and interspecific competition in plants. However, the effects of mixed plantations on the community structure and abundance of AM fungi are still unclear. Illumina MiSeq sequencing was used to investigate the AM fungal community in the roots and soils of pure and mixed plantations (Juglans mandshurica × Larix gmelinii). The objective of this study is to compare the differential responses of the root and rhizosphere soil AM fungal communities of Juglans mandshurica to long-term mixed plantation management. Results Glomus and Paraglomus were the dominant genera in the root samples, accounting for more than 80% of the sequences. Compared with that in the pure plantation, the relative abundance of Glomus was higher in the mixed plantation. Glomus, Diversispora and Paraglomus accounted for more than 85% of the sequences in the soil samples. The relative abundances of Diversispora and an unidentified genus of Glomeromycetes were higher and lower in the pure plantation, respectively. The Root_P samples (the roots in the pure plantation) had the highest number of unique OTUs (operational taxonomic units), which belonged mainly to an unidentified genus of Glomeromycetes, Paraglomus, Glomus and Acaulospora. The number of unique OTUs detected in the soil was lower than that in the roots. In both the root and soil samples, the forest type did not have a significant effect on AM fungal diversity, but the Sobs value and the Shannon, Chao1 and Ace indices of AM fungi in the roots were significantly higher than those in the soil. Conclusions Mixed forest management had little effect on the AM fungal community of Juglans mandshurica roots and significantly changed the community composition of the soil AM fungi, but not the diversity.

Leaf senescence is essential for the growth and development of deciduous trees in the next season. Larix gmelinii , a deciduous coniferous tree, exhibits its most distinctive feature by turning yellow in the autumn and eventually shedding its leaves, resulting in significant changes in its appearance during the fall. Lysine acetylation plays an important role in diverse cellular processes; however, limited knowledge is available regarding acetylations in the needle senescence of L. gmelinii. In this study, the proteomics and acetylated modification omics of two phenotypic leaves, yellow and green (senescent and non-senescent) needles, were analyzed before autumn defoliation. In total, 5022 proteins and 4469 unique acetylation sites in 2414 lysine acylated proteins were identified, and this resulted in the discovery of 1335 differentially expressed proteins (DEPs) and 605 differentially expressed acetylated proteins (DAPs) in yellow versus green needles. There are significant differences between the proteome and acetylome; only 269 proteins were found to be DEP and DAP, of which 136 proteins were consistently expressed in both the DEP and DAP, 91 proteins were upregulated, and 45 proteins were down-regulated. The DEPs participate in the metabolism of starch and sucrose, while the DAPs are involved in glycolysis and the tricarboxylic acid cycle. Among them, DEPs underwent significant changes in glycolysis and citric acid cycling. Most of the enzymes involved in glycolysis and the citrate cycle were acetylated. DAPs were down-regulated in glycolysis and up-regulated in the citrate cycle. In all, the results of this study reveal the important role of lysine acetylation in the senescence of L. gmelinii needles and provide a new perspective for understanding the molecular mechanism of leaf senescence and tree seasonal growth.

Quantifying the impact of competition on individual tree biomass and its distribution pattern can provide a basis for improving the prediction accuracy of forest biomass models. To accurately quantify the effects of competition factors on individual biomass and its distribution, we constructed three different individual biomass models by using nonlinear coupling equations based on the biomass survey data of 50 Larix gmelinii from 18 plots of Pangu Forest Farm in Daxing'an Mountains. M-1 was a traditional singly additive biomass model. M-2 and M-3 were models taking the distance dependent simple competition index (CI) and distance independent relative diameter ( R d ) into account, respectively. Those models were used to reveal the influence of competition factors on the prediction accuracy and distribution pattern of single tree biomass model of L. gmelinii . The results showed that the adjusted R 2 of three additive models ranged from 0.694 to 0.974, mean prediction errors ranged from -0.017 to 0.021, and mean absolute errors ranged from 0.152 to 0.357. The introduction of R d could improve the fitting degree and prediction accuracy of most biomass models, but CI did not affect the model fitting effect and prediction ability. Among the three models, M-3 model had the best performance, with good fitting degree and prediction accuracy of the biomass of each part, which could accurately estimate the single tree biomass of L. gmelinii . Further simulation results showed that the variation of biomass with DBH was mainly affected by CI and R d grade, and the influence of R d was stronger than CI. CI had greater influence on root and dry biomass, but less influence on branch and leaf biomass. R d had a more significant effect on biomass of branch and leaf than on that of root and trunk.

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)