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  1. Article ; Online: Carbon and Nitrogen Stocks in Three Types of Larix gmelinii Forests in Daxing’an Mountains, Northeast China

    Ruihan Xiao / Xiuling Man / Beixing Duan

    Forests, Vol 11, Iss 3, p

    2020  Volume 305

    Abstract: Studying carbon and nitrogen stocks in different types of larch forest ecosystems is of great significance for assessing the carbon sink capacity and nitrogen level in larch forests. To evaluate the effects of the differences of forest type on the carbon ...

    Abstract Studying carbon and nitrogen stocks in different types of larch forest ecosystems is of great significance for assessing the carbon sink capacity and nitrogen level in larch forests. To evaluate the effects of the differences of forest type on the carbon and nitrogen stock capacity of the larch forest ecosystem, we selected three typical types of larch forest ecosystems in the northern part of Daxing’an Mountains, which were the Rhododendron simsii - Larix gmelinii forest (RL), Ledum palustre - Larix gmelinii forest (LL) and Sphagnum-Bryum - Ledum palustre - Larix gmelinii forest (SLL), to determine the carbon and nitrogen stocks in the vegetation (trees and understories), litter and soil. Results showed that there were significant differences in carbon and nitrogen stocks among the three types of larch forest ecosystems, showing a sequence of SLL (288.01 Mg·ha −1 and 25.19 Mg·ha −1 ) > LL (176.52 Mg·ha −1 and 14.85 Mg·ha −1 ) > RL (153.93 Mg·ha −1 and 10.00 Mg·ha −1 ) ( P < 0.05). The largest proportions of carbon and nitrogen stocks were found in soils, accounting for 83.20%, 72.89% and 64.61% of carbon stocks and 98.61%, 97.58% and 96.00% of nitrogen stocks in the SLL, LL and RL, respectively. Also, it was found that significant differences among the three types of larch forest ecosystems in terms of soil carbon and nitrogen stocks (SLL > LL > RL) ( P < 0.05) were the primary reasons for the differences in the ecosystem carbon and nitrogen stocks. More than 79% of soil carbon and 51% of soil nitrogen at a depth of 0−100 cm were stored in the upper 50 cm of the soil pool. In the vegetation layer, due to the similar tree biomass carbon and nitrogen stocks, there were no significant differences in carbon and nitrogen stocks among the three types of larch forest ecosystems. The litter carbon stock in the SLL was significantly higher than that in the LL and RL ( P < 0.05), but no significant differences in nitrogen stock were found among them ( P > 0.05). These findings suggest that ...
    Keywords carbon and nitrogen stocks ; larch forest ; forest type ; environmental factors ; biomass ; Plant ecology ; QK900-989
    Subject code 333
    Language English
    Publishing date 2020-03-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Short-Term Litter Manipulations have Strong Impact on Soil Nitrogen Dynamics in Larix gmelinii Forest of Northeast China

    Ruihan Xiao / Xiuling Man / Beixing Duan / Tijiu Cai

    Forests, Vol 11, Iss 1205, p

    2020  Volume 1205

    Abstract: Changes in above-ground litterfall can influence below-ground biogeochemical processes in forests, which substantially impacts soil nitrogen (N) and nutrient cycling. However, how these soil processes respond to the litter manipulation is complex and ... ...

    Abstract Changes in above-ground litterfall can influence below-ground biogeochemical processes in forests, which substantially impacts soil nitrogen (N) and nutrient cycling. However, how these soil processes respond to the litter manipulation is complex and poorly understood, especially in the N-limiting boreal forest. We aimed to examine how soil N dynamics respond to litter manipulations in a boreal larch forest. A litter manipulation experiment including control, litter exclusion, and litter addition was performed in the Larix gmelinii forest on the north of the Daxing’an Mountains in China. Monthly soil inorganic N, microbial biomass and the rate of net N mineralization in both 0–10 cm and 10–20 cm layers, and N 2 O flux were analyzed from May 2018 to October 2018. In 0–20 cm soil layer the average soil inorganic N contents, microbial biomass N (MBN) contents, the rate of net N mineralization (Rmin), and the soil N 2 O emission in the litter addition plot were approximately 40.58%, 54.16%, 128.57%, and 38.52% greater, respectively than those in the control. While litter exclusion reduced those indexes about 29.04%, 19.84%, 80.98%, and 31.45%, respectively. Compared with the dynamics of the 10–20 cm soil layer, the N dynamics in 0–10 cm soil were more sensitive to litter manipulation. Rmin and N 2 O emissions were significantly correlated with MBN in most cases. Our results highlight the short-term effects of litter manipulations on soil N dynamics, which suggests that the influence of litter on soil N process should be considered in the future defoliation management of the boreal larch forest.
    Keywords litter input ; soil nitrogen availability ; soil nitrogen mineralization ; microbial biomass ; Soil N 2 O flux ; boreal forest ; Plant ecology ; QK900-989
    Language English
    Publishing date 2020-11-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Environmental Factors at Different Canopy Heights Had Significant Effects on Leaf Water-Use Efficiency in Cold-Temperate Larch Forest

    Zhaoxin Ge / Xiuling Man / Tijiu Cai / Beixing Duan / Ruihan Xiao / Zhipeng Xu

    Sustainability, Vol 14, Iss 5126, p

    2022  Volume 5126

    Abstract: It is of great significance to study short-term water-use efficiency (WUE s ) at different canopy heights for accurately evaluating the adaptability of cold-temperate larch ( Larix gmelinii ) forest to climate change. The stable isotope method combining ... ...

    Abstract It is of great significance to study short-term water-use efficiency (WUE s ) at different canopy heights for accurately evaluating the adaptability of cold-temperate larch ( Larix gmelinii ) forest to climate change. The stable isotope method combining data of gradient meteorology, photosynthetic properties and leaf structure were used to assess the influence of different canopy heights on short-term water-use efficiency (WUE s ) in larch forests in the northern Da Hinggan Mountains. The results show that: (1) The rank of leaf WUE s at different canopy heights was upper canopy > middle canopy > lower canopy. The leaf WUE s in upper canopy was significantly higher than those in the middle and lower canopy ( p < 0.01), and no significant difference was found between the middle and lower canopy ( p > 0.05). (2) The environmental factors, the photosynthetic characteristics, the specific leaf weight (LMA) and stomatal density (SD) had significant impact ( p < 0.05) on leaf WUE s at different canopy heights of larch forest. (3) The results of the weighted random forest analysis show that the main factor affecting WUE s in larch forests at different canopy heights was vapor pressure deficit (VPD), followed by relative humidity (RH) and net photosynthetic rate (Pn), while LMA and SD made relatively small contributions. This indicates that the variation of leaf WUE s at different canopy heights is mainly due to environmental factors. Our results highlight that the difference of environmental factors at different canopy heights should be considered in the future study of leaf WUE. Our results contribute to a better understanding of water utilization strategies and carbohydrate relations in the boreal forest ecosystems, which is of great significance for improving the sustainable management measures and strategies of boreal forest resources.
    Keywords cold-temperate zone ; larch forest ; canopy heights gradient ; WUE s ; influencing factors ; Environmental effects of industries and plants ; TD194-195 ; Renewable energy sources ; TJ807-830 ; Environmental sciences ; GE1-350
    Subject code 333
    Language English
    Publishing date 2022-04-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Increasing soil organic carbon and nitrogen stocks along with secondary forest succession in permafrost region of the Daxing’an mountains, northeast China

    Beixing Duan / Xiuling Man / Tijiu Cai / Ruihan Xiao / Zhaoxin Ge

    Global Ecology and Conservation, Vol 24, Iss , Pp e01258- (2020)

    2020  

    Abstract: Secondary forest succession plays a vital role in the dynamics of soil organic carbon and nitrogen and is recognized as an important driving force for the recovery of soil properties. In order to explore the effect of forest succession on the stocks of ... ...

    Abstract Secondary forest succession plays a vital role in the dynamics of soil organic carbon and nitrogen and is recognized as an important driving force for the recovery of soil properties. In order to explore the effect of forest succession on the stocks of soil organic carbon and nitrogen in permafrost region of the Daxing’an Mountains, northeast China, the Betula platyphylla forest at the early succession stage; the Betula platyphylla-Larix gmelinii mixed forest at the middle succession stage and the pure Larix gmelinii forest at the climax forest stage were selected to compare soil organic carbon and soil nitrogen stocks along forest succession stage. The results showed that the concentration of soil organic carbon (SOC) and total soil nitrogen (SN) all increased during forest succession, particularly in 0–40 cm depth. However, the C:N ratio changed slightly. The concentration of SOC and SN and the ratio of C/N significantly decreased with increasing of soil depth along forest succession. The stocks of total soil organic carbon (TSOC) and total soil nitrogen (TSN) increased from 77.69 Mg ha−1 to 130.50 Mg ha−1 and from 7.46 Mg ha−1 to 13.90 Mg ha−1, respectively, during forest succession, but the accumulation were mainly in later stage of succession from Betula platyphylla-Larix gmelinii forest to Larix gmelinii forest. TSOC and TSN showed obvious surface aggregation, with more than 58% of TSOC in the soil of 0–20 cm depth and more than 50% of TSN in the soil of 0–40 cm depth. TSOC and TSN decreased with increasing soil depth. To sum up, our study highlighted that secondary forest succession greatly increased the sequestration capacity of SOC and SN of forest soil in the future Daxing’an Mountains, northeast China. The result is of great significance for understanding the simultaneous effects of forest succession and climate change, and improving forest resource management measures and strategies in permafrost region.
    Keywords Secondary forest succession ; Soil organic carbon and soil nitrogen stocks ; C/N ratio ; Daxing’an mountains ; Boreal forest ; Ecology ; QH540-549.5
    Language English
    Publishing date 2020-12-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Effectiveness of a combined problem-based learning and flipped classroom teaching method in ophthalmic clinical skill training

    Anan Wang / Ruihan Xiao / Chun Zhang / Lin Yuan / Nana Lin / Lu Yan / Yaohua Wang / Jinhai Yu / Qin Huang / Puying Gan / Chao Xiong / Qihua Xu / Hongfei Liao

    BMC Medical Education, Vol 22, Iss 1, Pp 1-

    2022  Volume 10

    Abstract: Abstract Background Previous studies have primarily implemented problem-based learning (PBL) or flipped classroom (FC) teaching models in different majors; however, research on the combined PBL-FC teaching method in clinical medicine is scarce. Therefore, ...

    Abstract Abstract Background Previous studies have primarily implemented problem-based learning (PBL) or flipped classroom (FC) teaching models in different majors; however, research on the combined PBL-FC teaching method in clinical medicine is scarce. Therefore, we investigated the combined PBL-FC teaching method in teaching ocular trauma on students’ competencies. Method About 75 ophthalmology postgraduates were randomly divided into PBL-FC and traditional teaching groups. Students completed pre-and post-class theoretical examinations, skills evaluation, learning ability scales, and feedback questionnaires. Results Both groups showed significantly higher theoretical scores and improved learning ability. Feedback questionnaire scores of the PBL-FC group’s postgraduates without clinical experience were significantly higher than the traditional group’s for some items; there was no difference between groups in postgraduates with clinical experience. PBL-FC group’s pre-class preparation time was significantly longer than the traditional group’s, but the post-class review time was significantly shorter. PBL-FC group’s post-class theoretical performance was significantly higher than the traditional group’s. There was no statistical difference between the groups regarding skill operation. Among postgraduates without clinical experience, the PBL-FC group’s skill operation performance was significantly higher than the traditional group’s; for postgraduates with clinical experience, the traditional group’s skill operation performance was significantly higher than the PBL-FC group’s. Conclusions PBL-FC teaching is better for students without clinical experience or knowledge of ophthalmic diseases. Meanwhile, traditional teaching is a good choice for students with clinical experience who need more relevant knowledge.
    Keywords Problem-based learning ; Flipped classroom ; Clinical teaching ; Ocular trauma ; Special aspects of education ; LC8-6691 ; Medicine ; R
    Subject code 370
    Language English
    Publishing date 2022-06-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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