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horizontal structure of convergent wind shear associated with sporadic E layers over East Asia

Earth and Planetary Physics 2023年第5期7卷 548-557页

作者： LiHui Qiu Xian Lu Tao Yu Yosuke Yamazaki HuiXin Liu Yang-Yi Sun HaoNan Wu XiaoMin Zuo XiangXiang Yan Yan Yu YiFan Qi Institute of Geophysics&Geomatics China University of GeosciencesWuhan 430074China Department of Physics and Astronomy Clemson UniversityClemsonSC 29631USA Leibniz institute of Atmospheric Physics at the University of Rostock 18225 KühlungsbornGermany Department of Earth and Planetary Sciences Kyushu UniversityFukuoka 8190395Japan School of Mathematics and Physics China University of GeosciencesWuhan 430074China

At present,the main detection instruments for observing sporadic E(Es)layers are ground-based radars,dense networks of ground-based global navigation satellite system(GNSS)receivers,and GNSS radio occultation,but they cannot capture the whole picture of the horizontal structure of Es *** study employs the Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension model(WACCM-X 2.1)to derive the horizontal structure of the ion convergence region(HSICR)to explore the shapes of the large-scale Es layers over East Asia for the period from June 1 to August 31,*** simulation produced the various shapes of the HSICRs elongated in the northwest-southeast,northeast-southwest,or composed of individual small *** close connection between Es layer critical frequency(foEs)and vertical ion convergence indicates that the HSICR is a good candidate for revealing and explaining the horizontal structure of the large-scale Es layers.

关键词： sporadic E layer horizontal structure wind shear WACCM-X model

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Dramatic changes in the horizontal structure of mangrove forests in the largest delta of the northern Beibu Gulf, China

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Acta Oceanologica Sinica 2023年第7期42卷 116-123页

作者： Riming Wang Zhijun Dai Hu Huang Xixing Liang Xiaoyan Zhou Zhenming Ge Baoqing Hu Guangxi Key Laboratory of Marine Environmental Change and Disaster in Beibu Gulf/Beibu Gulf Ocean Development Research Center Beibu Gulf UniversityQinzhou 535011China State Key Laboratory of Estuarine and Costal Research East China Normal UniversityShanghai 200062China Key Laboratory of Environment Change and Resources Use in Beibu Gulf(Nanning Normal University) Ministry of EducationNanning 510310China

The horizontal structure of mangrove forests is an important characteristic that reflects a significant signal for coupling between mangroves and external *** the loss and gain of mangroves has received much attention,little information about how the horizontal structure of mangrove forests develops from the seedling stage to maturity has been ***,remote sensing images taken over approximately 15 years,UVA images,nutrient elements,sediments,and Aegiceras corniculatum vegetation parameters of the ecological quadrats along the Nanliu Delta,the largest delta of the northern Beibu Gulf in China,are analyzed to reveal changes in the horizontal structure of mangroves and their associated driving *** results show that both discrete structures and agglomerated structures can often be found in *** seedlings and ***,the combination of seedlings growing into maturity and new seedlings filling in available gaps causes the discrete structure of *** to gradually vanish and the agglomerate structure to become *** aggregated structure of seedlings,compared to the discrete structure,can enhance the elevation beneath mangroves by trapping significantly more sediments,providing available spaces and conditions for seedlings to continue ***,by catching fine sediments with enriched nutrients,the survival rate of *** seedlings in the agglomerated structure can be much higher than that in the discrete *** results highlight the significance of the agglomeration of ***,which can be beneficial to coastal mangrove restoration and management.

关键词： deltaic mangrove Aegiceras corniculatum horizontal structure biomorphodynamic processes Nanliu Delta

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Plant Biodiversity and structure of Robusta Coffee (Coffea canephora var. robusta) Agroforests in Cameroon

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Open Journal of Forestry 2023年第2期13卷 225-241页

作者： Ngomeni Arlende Flore Chimi Djomo Cédric Kabelong Banoho Louis Paul Roger Temgoua Lucie Félicité Avana Marie Louise Tchamba Ngankam Martin Bidzanga Nnomo Lucien Emmanuel Institute of Agricultural Research for the Development (IRAD) Yaounde Cameroon Institute of Agricultural Research for the Development (IRAD) Yokadouma Cameroon Plant Systematics and Ecology Unit Laboratory of Botany and Ecology Department of Plant Biology Faculty of Science University of Yaounde I Yaoundé Cameroon Laboratory of Environmental Geomatics Department of Forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon

Agroforests are man-made ecosystems in which crops are associated with a main perennial species like Robusta Coffee Agroforests (RCAs), which is counted among the main modes of perennial crops production in Cameroon. Despite the rich ecosystem services provided, the diversity of Associated Species (AS) found in these RCAs and the structure of the landscapes they form remain little known in Cameroon. The current study aimed to inventory AS and characterize the structure of RCAs in four sites (Ayos, Malantouen, Melong and Nkongsamba) belonging to three robusta coffee production basins in Cameroon. A systematic inventory with dendrometric measurements of the wood AS and coffee trees was carried out on 120 one-hectare plot unit, i.e. 30 plots per site. The results showed that 102 AS belonging to 83 genera and 41 families were identified in these RCAs. The RCAs of Ayos in the dense rainforest zone with bimodal rainfall pattern were the most diverse with 71 species, followed by those of Melong and Nkongsamba with respectively 39 and 33 species respectively in the dense rainforest zone with monomodal rainfall pattern, and Malantouen with 33 species in the high savannahs of the west. Structurally, average coffee tree and AS densities founded ranged from 1208 - 1456 plants/ha and 71 - 214 stems/ha and those of basal area from 7.29 - 17.40 m2/ha for coffee trees and 7.97 - 16.14 m2/ha for AS in function of site. Basis on the vertical stratification, the proportion of the 3 - 6 m stratum, which is mainly represented by introduced AS, varied from 38% - 62% depending on the site. The results of this study showed that RCAs contribute to the conservation of plant biodiversity, given the specific richness identified in these ecosystems.

关键词： Associated Species Species Richness horizontal structure Vertical structure Production Basin

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Relationship between structure and Shelter Effect for Metasequoia Glyptostroboides Shelterbelt

Relationship between Structure and Shelter Effect for Metase...

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第十三届中国科协年会第16分会场-沿海生态建设与城乡人居环境学术研讨会

作者： Geoff WANG Department Forestry and Natural Resources Clemson University

Shelterbelts provide areas of shelter and reduce wind speed in their leeThis work monitored relationship between structure and shelter effect of wide (three-dimensional) shelterbeltsMean wind speed was measured within and around 16 Metasequoia glyptostroboides forest plots of various horizontal and vertical structuresOur results show that for these wide forests, the vertical structure indices of crown index (CI) and proportion of large trees (LT) are useful for predicting the wind shelter effect as either the shelter distance (d70) or the minimum relative wind speed (Um/U0)The shelter effect generally firstly increases and then decreases with the increasing of CI and LTUsing forest community classification, the optimum values of CI and LT are identified for Mglyptostroboides forest.

关键词： Vertical structure horizontal structure Shelter distance Minimum relative wind speed Metasequoia glyptostroboides shelterbelt

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