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1Zircon U-Pb SHRIMP ages of the Taiping (calc-alkaline)-Huangshan (alkaline) composite intrusion:Constraints on Mesozoic lithospheric thinning of the southeastern Yangtze Craton,China显示文摘The Taiping-Huangshan composite intrusion is a unique complex with characteristics changing from calc-alkaline (Taiping intrusion) to alkaline (Huangshan intrusion). Huangshan intrusion samples show a spectacular tetrad effect in their REE distribution patterns as well as non-CHARAC (charge-and radius-controlled) trace element behavior, indicating a highly evolved late-stage magma component. This composite intrusion provides a rare opportunity to investigate the variance of tectonic setting and lithospheric thinning of the southeastern Yangtze Craton in late Mesozoic era. Zircon SHRIMP U-Pb analyses yield an emplacement age of 140.6±1.2 Ma for the Taiping intrusion, and ages of 127.7±1.3, 125.7±1.4, 125.1±1.5, and 125.2±5.5 Ma for four samples from the Huangshan intrusion respectively. The ages for four different phases of the Huangshan intrusion agree within their small analytical errors, indicating that the emplacement was in a short time. The Taiping and Huangshan intrusions are intimately associated, but there is about 15 Ma interval between their intrusion, and the magma characters change from calc-alkaline to alkaline without transition. This probably corresponds to lithospheric thinning of the southeastern Yangtze Craton. This event possibly happened from about 141 Ma (the emplacement age of the Taiping intrusion), to 128 Ma (start of emplacement of the Huangshan intrusion). The thinning mechanism is dominantly delamination.XUE HuaiMin WANG YingGeng MA Fang WANG Cheng WAN DeEn ZUO YanLong 2009Science China Earth Sciences2009,52,11:28
2LA-ICP-MS zircon U-Pb dating and phenocryst EPMA of dikes, Guocheng, Jiaodong Peninsula: Implications for North China Craton lithosphere evolution显示文摘Widespread dike swarm, including diorite-, monzonite-porphyry and lamprophyre, intruded in the al- tered breccia gold deposits along basin marginal faults, Guocheng, Jiaodong Peninsula. Petrography exhibits biotite enclaves in amphibole phenocrysts and the presence of acicular apatites in these dikes. Electron probe microanalyses (EPMA) show that the amphibole and clinopyroxene phenocryst’s mantle in diorite porphyry and lamprophyre respectively has sharply higher MgO (Mg#) and Cr2O3 contents in contrast to their cores. The plagioclase phenocryst in monzonite porphyry has reverse zoning. These results indicate that the magma mixing between mantle-derived mafic and crust-derived felsic magmas occurred in the original process of the dikes. Zircon cathodoluminescence (CL) images show well-developed magmatic oscillatory zones and the acquired LA-ICP-MS zircon U-Pb weighted mean 206Pb/238U ages are 114±2 Ma (MSDW=1.5) for monzonite porphyry (GS1) and 116±1 Ma (MSDW=0.8) for diorite porphyry (GS2), respectively. Earlier magmatic events in the northwest Jiaodong Peninsula represented by some inherited or captured zircons also occur in these dikes. Magmatic zircons from GS1 and GS2 display consistent chondrite-normalized REE patterns and Nb/Ta values, implying that they may share a similar or same source. HREE enrichment and obvious negative Eu anomalies of these zircons preclude garnet presented in their source. Our results, combined with preciously pub- lished data, indicate that dike intrusion and gold mineralization among quartz vein, altered tectonite and altered breccia gold deposits are broadly contemporaneous throughout the Jiaodong Peninsula. These also imply that the intensive crust-mantle interaction and asthenospheric underplating had oc- curred in the Early Cretaceous in the Peninsula, together with foundering of lower crust in the early Mesozoic, representing the different stages of lithosphere thinning in the North China Craton (NNC).TAN Jun WEI JunHao GUO LingLi ZHANG KeQing YAO ChunLiang LU JianPei LI HongMei 2008Science China Earth Sciences2008,51,10:23
3华北克拉通晚中生代壳-幔拆离作用:岩石流变学约束显示文摘大陆岩石圈的流变学结构对于岩石圈深部过程(壳/幔过程)有着深刻的影响,直接表现在岩石圈壳-幔结构与浅部构造上。本文注意到华北克拉通晚中生代岩石圈减薄期间地壳的伸展、拆离与减薄在不同地区的宏观、微观构造及地壳岩石流变学等方面的差异表现与区域变化,以及现今和晚中生代时期岩石圈厚度的不均匀性。讨论了以水为主体的地质流体的存在对于岩石圈流变性的影响。综合克拉通东部与西部地壳/地幔厚度变化特点以及下地壳和上地幔含水性特点,阐述了晚中生代时期华北克拉通岩石圈内部壳幔耦合与解耦的规律,提出了华北岩石圈壳-幔拆离作用模型以解释华北克拉通晚中生代岩石圈减薄的基本现象与深部过程。提出区域性伸展作用是岩石圈减薄的主要动力学因素,东部地区在晚中生代伸展作用过程中壳-幔具有典型的解耦性,上部地壳、下部地壳和岩石圈地幔的变形具有显著差异性。而西部区壳幔总体具有耦合性,下地壳与岩石圈地幔共同构成流变学强度很高且难以变形的岩石圈根。刘俊来 纪沫 夏浩然 刘正宏 周永胜 余心起 张宏远 程素华 2009岩石学报2009,25,8:18
4Genesis of the Hongzhen metamorphic core complex and its tectonic implications显示文摘The Hongzhen metamorphic core complex is situated in the Yangtze plate to the east of the Dabie oro- genic belt. Its ductile detachment zone in the foot wall overprints on the metamorphic complex of the Proterozoic Dongling Group. The present profile of the ductile shear zone with consistent SW-dipping mineral elongation lineation shows antiform and reversed S-shape from northeast to southwest respectively. Exposure structures, microstructures and quartz C-axis fabric all indicate top-to-SW movement for the ductile shear zone. Recrystallisation types of quartz and feldspar in the mylonites demonstrate that the shear zone was developed under the amphibolite facies condition and at mid-crust levels. The metamorphic core complex formed in the Early Cretaceous with a muscovite plateau age of 124.8±1.2 Ma. Regional NE-SW extension along a SW-dipping, gentle detachment zone was responsible for formation of the core complex. Intrusion of the Hongzhen granite with a biotite plateau age of 124.8±1.2 Ma rendered the ductile shear zone curved, uplifted and final localization of the core complex. The Hongzhen metamorphic core complex suggests that the Early Cretaceous magma- tism in this region took place under the condition of regional extension and the eastern Yangtze plate also experienced lithospheric thinning.ZHU Guang XIE ChengLong XIANG BiWei HU ZhaoQi WANG YongSheng LI Xing 2007Science China Earth Sciences2007,50,5:10
5Retinal nerve fiber layer thickness changes in obstructive sleep apnea syndrome: one year follow-up results显示文摘·AIM: To investigate the retinal nerve fiber layer(RNFL)thickness changes in patients with obstructive sleep apnea syndrome(OSAS) for one year follow-up. To discuss the possibility of detecting tendency of glaucoma in this population by using spectral domain optical coherence tomography(3D-OCT-2000 Spectral domain).·METHODS: After polysomnographic study, all subjects(64 OSAS patients and 40 controls) underwent detailed ophthalmological examination. After these examinations,patients with glaucoma and patients who had ophthalmological and/or systemic disease were excluded from the study.Totally, 20 patients in OSAS group and five patients in controls were excluded from the study in the first examination and follow-up period. The RNFL thickness was assessed with OCT. Forty-four OSAS patients and 35 control subjects were followed up for12 mo. RNFL thickness change and OSAS patients were evaluated for severity of disease by Apnea-Hypopnea Index(AHI).·RESULTS: Forty-four OSAS patients and 35 controls were enrolled in the study. Statistically significance was found between OSAS patients and controls at the 12 thmo.Average RNFL thickness was found to be significantly lower in last measurements in OSAS patients when compared with first measurements and control subjects(P <0.001, 0.002, respectively). There was a statistically significant correlation among AHI, and RNFL thickness(P <0.05).·CONCLUSION: The results suggest that the patients with OSAS were related with a proportional decrease in the RNFL thickness. These patients should be followed up regularly for glaucomatous changes. Detecting more RNFL thinning in severe OSAS was important.Mehmet Ozgur Zengin Ibrahim Tuncer Eyyup Karahan 2014International Journal of Ophthalmology(English edition)2014,7,4:9
6Thermal regime transition in eastern North China and its tectonic implication显示文摘The pre-Cenozoic formation in the Cenozoic depositon centres in eastern North China reached its maximum temperature at present, and the earlier paleo-temperature, therefore, has been overprinted, but the record of paleo-temperature by the vitrinite reflectance (Ro) has not been overprinted by the later thermal events in the pre-Cenozoic formation located in the uplift or in the Paleozoic-Mesozoic residual basins out of the Cenozoic depositon centres. The reconstruction of paleo-temperature gradient and paleo-heat flow, based on the vitrinite reflectance in the Paleozoic and the Mesozoic structural layers in boreholes, indicated that the eastern North China was characterized by much higher paleo-temperature gradient (40-55℃/km) and heat flow (>80 mW/m2) during the Middle-Late Mesozoic than those in the Early Mesozoic and at present. The higher paleo-heat flow during the Middle-Late Mesozoic implies that the thickness of the 'thermal' lithosphere at that time was just 50-55 km, it had been much thinned relative to the thickness (135-148 km) at the Early Mesozoic. The transition of near-surface thermal regime in eastern North China occurred around 110 Ma, and the corresponding deep tectonothermal processes should take place at ~160 Ma.FU Mingxi HU Shengbiao WANG Jiyang 2005Science China Earth Sciences2005,48,6:8
7Late Mesozoic magmatism in the Jiaodong Peninsula,East China:Implications for crust-mantle interactions and lithospheric thinning of the eastern North China Craton显示文摘A section from the Linglong gold deposit on the northwestern Jiaodong Peninsula,East China,containing Late Mesozoic magmatic rocks from mafic and intermediate dikes and felsic intrusions,was chosen to investigate the lithospheric evolution of the eastern North China Craton(NCC).Zircon U-Pb data showed that low-Mg adakitic monzogranites and granodiorite intrusions were emplaced during the Late Jurassic(~145 Ma) and late Early Cretaceous(112-107 Ma),respectively;high-Mg adakitic diorite and mafic dikes were also emplaced during the Early Cretaceous at^139 Ma and ~118 Ma,and 125-145 Ma and 115-120 Ma,respectively.The geochemical data,including whole-rock major and trace element compositions and Sr-Nd-Pb isotopes,imply that the mafic dikes originated from the partial melting of a lithospheric mantle metasomatised through hydrous fluids from a subducted oceanic slab.Low-Mg adakitic monzogranites and granodiorite intrusions originated from the partial melting of the thickened lower crust of the NCC,while high-Mg adakitic diorite dikes originated from the mixing of mafic and felsic melts.Late Mesozoic magmatism showed that lithosphere-derived melts showed a similar source depth and that crust-derived felsic melts originated from the continuously thickened lower crust of the Jiaodong Peninsula from the Late Jurassic to Early Cretaceous.We infer that the lower crust of the eastern NCC was thickened through compression and subduction of the Palaeo-Pacific plate beneath the NCC during the Middle Jurassic.Slab rollback of the plate from ~160 Ma resulted in lithospheric thinning and accompanied Late Mesozoic magmatism.Yayun Liang Xuefei Liu Qingfei Wang Rui Zhao Yao Ma 2020Geoscience Frontiers2020,11,3:5
8Experimental and Numerical Investigation on Erosion Corrosion of the Air Cooler Tube Bundle in a Residue Hydrotreating Unit显示文摘Corrosion leakage occurred in the 14th tube bundle in the first row of a residual oil hydrotreating air cooler after operating for two years.The failure location was 0.5 m from the outlet header box.In this paper,the erosion corrosion of the air cooler tube bundle was investigated by experimental and numerical methods.Visual inspection,scanning electron microscopy(SEM),and X-ray diffraction(XRD)experiments were performed,and the failure morphology and material composition confirmed that the damage was caused by erosion corrosion.The shear stress transport k–ωturbulence model(SST-k–ω)was then used to investigate the flow and erosion corrosion characteristics,combined with mass transfer,corrosion rate,and ionization equilibrium models.The numerical simulation results revealed that the water phase volume fraction increased with flow and heat transfer in the fluid,which increased the mass flow rate and concentration of hydrogen sulfide.The mass transfer coefficient and corrosion rate were proposed as important parameters to characterize erosion corrosion.Moreover,the local concentration of wall shear stress was found to increase the risk of erosion corrosion.The predicted high-risk area was consistent with the actual failure area,which verified that this failure incident was attributable to erosion corrosion by the water phase.Jin Haozhe Yu Chenyang Gu Youjie Qian Guangwei Liu Xiaofei Ou Guofu Jia Yongna 2022China Petroleum Processing & Petrochemical Technology2022,24,4:2
9EXPERIMENTAL APPLICATION OF A THINNING SCHEME FOR THE ASSIMILATION OF SURFACE OBSERVATION DATA IN GRAPES-3DVAR显示文摘To reduce the spatial correlation of representation error in observations and computational complexity, we propose a thinning scheme that can extract typical observations within a certain range. This scheme is applied to the Global/Regional Assimilation and Prediction System(GRAPES) with three-dimensional variation(3 DVAR) to study the effect of the thinning radius on the assimilation results. The assimilation experiments indicate that when the ratio of the model resolution to the observational resolution is 1:3, the simulated results for precipitation are relatively good and have a relatively high equitable threat score(ETS). Moreover, the analysis errors in the temperature and the specific humidity are the smallest, the dependence of the norm gradient vector of the objective function on the number of iterations is slow, gentle, and close to 0, and the minimization results in improved conditions.赵虹 刘寅 2018Journal of Tropical Meteorology2018,24,3:2
10MATHEMATIC MODELS OF THINNING PATTERN FOR NON-SPHERE SUPERPLASTIC FREE BULGING(Ⅰ)显示文摘As clamping periphery is fixed during superplastic bulging, the thinning of thickness iscertainly inhomogeneous. There are large deviations between the mathematic model of athinning pattern established formerly for free bulging and the real deformation. In this paper,the mathematic model of a thinning pattern about non-spheric free bulging is establishedfor the first time by means of a function simulation method, and a simple and convenientmethod to determine the concrete form of this model in application is suggested. The agree-ment between the theoretical curve and the measured values proved to be perfect. Since themodel is established according to the experimental data of typical superplastic alloys, it canbe considered as a proper representation. This method is of general significance to bothnon-typical superplastic alloys and tough materials.宋玉泉 左万永 1992Science China Mathematics1992,35,1:2
11Natural regeneration responses to thinning and burning treatments in ponderosa pine forests and implications for restoration显示文摘Understanding naturally occurring pine regeneration dynamics in response to thinning and burning treatments is necessary not only to measure the longevity of the restoration or fuels treatment,but also to assess how well regeneration meets forest sustainability guidelines and whether natural regeneration is sufficient for maintaining a sustainable forest structure and composition.A synthesis review was carried out on the effects of mechanical thinning and prescribed burn treatments on natural pine regeneration response in frequent-fire ponderosa pine forests across the western United States.The focus was on site-specific variability in pine regeneration dynamics,temporal trends in regeneration presence and abundance,and response to treatment as described in the current literature using 29 studies that met our evidence-based review protocols.Data showed that the effects of thinning and burning treatments on regeneration depended on time since treatment.Mechanical thinning,prescribed burning,and thinning plus burn treatments all increased seedling density,but there was high variability among sites and studies.There were mixed results in the short-term(<10 years)with both increasing and decreasing regeneration,and a general increase in regeneration 11−20 years post-treatment.Some long-term studies(>20 years)concluded that stands can return to pre-treatment densities in terms of total trees per hectare and forest floor duff levels when there are no maintenance treatments applied.Several studies showed the average ponderosa pine seedling presence,survival and growth found in today’s forests to be at a high density;this combined with missed fire cycles could contribute to future fire risk and reduce the efficacy of maintaining fuel reduction goals.Tzeidle N.Wasserman Amy E.M.Waltz John Paul Roccaforte Judith D.Springer Joseph E.Crouse 2022Journal of Forestry Research2022,33,3:1
12Models for economic evaluation of multi-purpose apple harvest platform and software development显示文摘An increasing number of U.S.apple growers are now interested in using harvest platforms to increase harvest productivity,expand labor pool,and alleviate tough working conditions.To maximize benefits,functions of thinning,pruning&training,and infield sorting have been or are to be incorporated into harvest platforms.Though growers are most concerned with economic benefits,few cost-benefit studies had been conducted on different platforms.In the meantime,economic analysis procedure is complex and each analysis is for one specific machine(not for general purposes).No software has been developed as a general and ready-to-use tool for growers and researchers for the platform economic analysis.In this study,platforms,both available on the marketplace and developed in lab as pilot trials,were reviewed.Costs and benefits models were then established,based on which multi-purpose apple harvest platform economic evaluation software(iMPAHP)was developed(capable of evaluating a wide variety of apple harvest platforms).A case study(machine cost of$100000,accommodating 6 workers,processing apple incidence of 10%with 90%sort-out rate,and harvest,thinning,and pruning&training productivity increase by 40%,50%,and 60%,respectively)based on iMPAHP demonstrated that infield sorting,harvest,thinning,and pruning and training accounted for 48.4%,23.9%,14.3%,and 13.4%of the total benefits,respectively.In the case that the platform was in all-four-purpose-application,the net present value(NPV)analysis of a 10-year investment showed a positive return of$60547.However,without infield sorting function,the NPV resulted in a negative value,indicating a loss for the machine investment.Though incorporating the modular infield sorting system certainly increased the overall machine investment by$30000,the benefits outweighed the costs.Zhao Zhang Zhaohua Zhang Xinmiao Wang Hu Liu Yuanjie Wang Weijie Wang 2019International Journal of Agricultural and Biological Engineering2019,12,1:1
13Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior显示文摘The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We used therefore start-up experiments with constant shear rates and can speak consequently of shear stress instead of viscosity.The shear stress increases sharply at the beginning of the stress growth experiment,passes an overshoot and begins to decrease up to the steady state shear stress.We can assume that a stress growth curve with an overshoot points out to thixotropic behavior.After the steady state shear stress is reached,the shear deformation is stopped,and the stress relaxation begins.It is to be expected that the shear stress will recover after the stress relaxation.Systems with shear thinning and plastic flow behavior were examined.The thixotropy is discussed in relation to the flow behavior.Stress growth experiments were performed with shear rates from the first Newtonian region and from the shear thinning region of the systems with shear thinning flow behavior.Stress start-up experiments were carrying out with shear rates from the first and second yield stress regions and from the transition section of a system with plastic flow behavior.Dimiter Hadjistamov 2019材料科学与工程(中英文B版)2019,9,2:1
14Experimental study on the special shear thinning process of a kind of non-Newtonian fluid显示文摘To study the effect of long chain molecule and surface active agent on non-Newtonian fluid properties, rheological experiments on two different fluids have been done. The first group of the fluid is the hydroxyethyl cellulose water solution, and the second is the water solution containing the mixture of dodecyl- triethyl ammonium bromide and lauryl sodium sulfate. With the increasing shear rate, shear thinning phenomenon appears in the first group of solution, and a spe- cial shear thickening-shear thinning phenomenon appears in the second group. It is considered that the special rheological phenomenon is caused by the difference between the aggregating and the departing speed of the colloidal particles formed in the fluid. The difference between the two speeds relates with the shear rate. The experiment results indicate that the rheological properties can be designed by choosing proper additives at a certain shear rate, and such a fluid with special vis- cosity variation should be included in the classification of the non-Newtonian fluid.CHEN HaoSheng CHEN DaRong WANG JiaDao LI YongJian 2007Science China(Technological Sciences)2007,50,2:1
15Rheological properties of salt-tolerant HPAM solutions with ultrahigh molecular weight显示文摘The rheological properties of salt-tolerant partially hydrolyzed polyacrylamide(HPAM)solutions with molecular of 2.5×107 g/mol at different concentrations were measured in steady-state shear flow mode by Haake Rheostress 150 rheometer.Three constitutive equations(Oldroyd four constant model,Guesekus model and FENE-P model) were used for describing the apparent viscosity and first normal stress difference.The apparent viscosity of salt-tolerant HPAM solutions appears a first Newtonian zone when the shear rate is approximately lower than 0.2 s-1.At high shear rate,the HPAM solutions show shear-thinning and elasticity.The results show that the FENE-P model has the best agreement between theoretical and experimental data within the available shear rate range.The material parameters are useful for numerical analysis of polymer solution flow fields.张敏革 张吕鸿 姜斌 李鑫钢 2008Journal of Central South University2008,15,S1:1
16Bilateral scleromalacia perforans and peripheral corneal thinning in Wegener's granulomatosis显示文摘A rare case of bilateral scleromalacia perforans, bilateral peripheral corneal thinning (contact lens cornea) and unilateral orbital inflammatory disease in a 50 years old female patient with an indolent form Wegener's granulomatosis(WG) involving lungs and sinuses is reported. The patient survived for 12 years after the initial diagnosis of systemic disease. There was perforation of left globe following trauma and no perforation of the right globe till the last follow up of the patient.S C Reddy I Tajunisah T Rohana 2011International Journal of Ophthalmology(English edition)2011,4,4:1
17A meta-analysis of the impacts of forest logging on soil CO2 efflux显示文摘Soil CO2 efflux,the second largest flux in a forest carbon budget,plays an important role in global carbon cycling.Forest logging is expected to have large effects on soil CO2 efflux and carbon sequestration in forest ecosystems.However,a comprehensive understanding of soil CO2 efflux dynamics in response to forest logging remains elusive due to large variability in results obtained across individual studies.Here,we used a meta-analysis approach to synthesize the results of 77 individual field studies to determine the impacts of forest logging on soil CO2 efflux.Our results reveal that forest logging significantly stimulated soil CO2 efflux of the growing season by 5.02%.However,averaged across all studies,nonsignificant effect was detected following forest logging.The large variation among forest logging impacts was best explained by forest type,logging type,and time since logging.Soil CO2 efflux in coniferous forests exhibited a significant increase(4.38%)due to forest logging,while mixed and hardwood forests showed no significant change.Logging type also had a significant effect on soil CO2 efflux,with thinning increasing soil CO2 efflux by 12.05%,while clear-cutting decreasing soil CO2 efflux by 8.63%.The time since logging also had variable effects,with higher soil CO2 efflux for 2 years after logging,and lower for 3-6 years after logging;when exceeded 6 years,soil CO2 efflux increased.As significantly negative impacts of forest logging were detected on fine root biomass,the general positive effects on soil CO2 efflux can be explained by the accelerated decomposition of organic matter as a result of elevated soil temperature and organic substrate quality.Our results demonstrate that forest logging had potentially negative effects on carbon sequestration in forest ecosystems.LongFei Chen YangZhou Xiang ZhiBin He Jun Du PengFei Lin Xi Zhu 2020Research in Cold and Arid Regions2020,12,3:1
18Edge-driven convection and thinning of craton lithosphere:Two-dimensional thermal-mechanical modeling显示文摘There are usually abrupt changes in lithospheric thickness at the boundaries between ancient cratons and adjacent young mobile belts.Lateral variations in temperature and density between the two can trigger small-scale mantle convection(edge-driven convection,EDC).Here,we use two-dimensional thermal-mechanical simulations to explore the EDC caused by the lithospheric step between a craton and a mobile belt,and its role in the thinning of the craton lithosphere.The results show that the impact of EDC on a craton depends on the properties of the craton lithosphere and on their contrasts with the adjacent mobile belt,given the same initial condition.When the craton lithospheric density is relatively large,a high-strength craton has strong ability to resist EDC,and craton lithospheric thinning is limited to the edge.In contrast,the ability of a low-strength craton to resist EDC is weak,and the craton lithosphere is gradually eroded by the downward flow,eventually leading to large-scale thinning of the cratonic lithosphere.When the craton lithospheric density is relatively small,regardless of the strength of the cratonic lithosphere,the craton can well withstand the impacts of EDC.In this case,upwelling flow drives cratonic lithosphere materials to the base of the mobile belt,and lithospheric thinning only occurs at the edge of the craton lithosphere.The Archean North China Craton(NCC)was surrounded by Phanerozoic mobile belts,and its lithospheric thinning first occurred on the northern and eastern margins,a process that lasted for a long time.We suggest that EDC has played an important role in lithospheric thinning of the NCC,in particular the initiation of lithospheric thinning,but we cannot rule out the additional contributions from other mechanisms.Danhong LIU Lin CHEN 2019Science China Earth Sciences2019,62,12:1
19Changes in carbon stocks of soil and forest floor in black pine plantations in Turkey显示文摘The objectives of this study were:(1)to determine carbon stock changes in the soil and forest floor of black pine(Pinus nigra subsp.pallasiana)plantations in Turkey;(2)to determine the effects of thinning on annual carbon accumulation in both;and,(3)to investigate relationships between annual carbon storage in soil and forest floor and stand characteristics of black pine.Samples were taken in 90 plots from stands at the pole(dbh=11.0–19.9 cm)and sawlog(dbh=20.0–35.9 cm)stages.Carbon analyses of soil and forest floor samples showed that in unthinned plantations signifi cant organic carbon was sequestered an average of 1.47 Mg ha^−1 a^−1 in the soil and 0.20 Mg ha^−1 a^−1 in the forest floor.Organic carbon sequestered annually in the soil was signifi cantly lower in thinned than in unthinned stands,while diff erences in the forest floor were insignifi cant.There were positive correlations between carbon sequestered in the soil and stand age,average DBH,mean stand height,basal area,and site index.Carbon sequestered the forest floor increased with basal area.As a result,carbon sequestered in the soil should not be ignored in greenhouse gas inventories because carbon stored belowground was approximately 70%of the aboveground pool.SükrüTeoman Güner Dilek Güner 2021Journal of Forestry Research2021,32,1:1
20Late-entry commercial thinning effects on Pinus banksiana:growth, yield, and stand dynamics in Québec, Canada显示文摘We studied late-entry commercial thinning effects on growth, yield, and regeneration in a 48-year-old jack pine(Pinus banksiana Lamb.) stand. Applied thinning intensities were 27, 32, and 47% of merchantable basal area(BA) excluding skidding trails. After 15 years, mean diameter at breast height of surviving trees in the 47% BA removal increased by 4.9 cm(25%) compared to the unthinned control. The 47% BA removal also increased gross merchantable volume(GMV) tree-1by 46% compared to the control. The 27% BA removal had twice as much GMV ha-1compared to the 47% BA removal after15 years. Moreover, cumulative GMV ha-1was much higher in the 27% BA removal than in the unthinned control. The highest thinning intensity produced larger trees on average, while the lowest thinning intensity maximized volume production per hectare. Maintenance of acceptable growing stock throughout the 15-year period in the 27% BA removal could provide other ecosystem functions such as biodiversity enhancement or wildlife habitat by delaying senescence. Regeneration data showed that a shift in species composition occurred in the understory. After 15 years, the understory was dominated by black spruce(Picea mariana(Mill.) B.S.P.), white birch(Betula papyrifera Marsh.), and trembling aspen(Populus tremuloides Michx.). If regenerating jack pine is an objective after final overstory removal, additional efforts will be needed to re-establish this species.Martin-Michel Gauthier Stéphane Tremblay 2019Journal of Forestry Research2019,30,1:1
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