The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Jingxin Wang - One of the best experts on this subject based on the ideXlab platform.
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effects of rainfall on soil moisture and water movement in a subalpine dark Coniferous Forest in southwestern china
Hydrological Processes, 2012Co-Authors: Shirong Liu, Xianchong Wan, Chunqian Jiang, Xianfang Song, Jingxin WangAbstract:Water content and movement in soil profile and hydrogen isotope composition (dD) of soil water, rainwater, and groundwater were examined in a subalpine dark Coniferous Forest in the Wolong National Nature Reserve in Sichuan, China, following rainfall events in 20032004. Light rainfall increased water content in the litter and at soil depth of 080?cm, but the increased soil water was lost in several days. Heavy rainfall increased soil water content up to 85% at depths of 040?cm. Following the light rainfall in early spring, the dD of water from the litter, humus, illuvial, and material layers decreased first and then gradually reached the pre-rainfall level. In summer, light rainfall reached the litter humus, and illuvial layer, but did not hit the material layer. Heavy rainfall affected dD of water in all layers. The dD of soil interflow slightly fluctuated with rainfall events. The dD of shallow groundwater did not differ significantly among all rainfall events. Light rainfall altered the shape of dD profile curve of water in the upper layer of soil, whereas heavy rainfall greatly affected the shape of dD profile curve of water in all soil layers. Following the heavy rainfall, preferential flow initially occurred through macropores, decayed plant roots, and rocks at different depths of soil profile. With continuing rainfall, the litter and surface soil were nearly saturated or fully saturated, and infiltration became homogeneous and plug-like. Forest soil water, particularly in deeper soil profile, was slightly affected by rainfall and, thus, can be a source of water supply for regional needs, particularly during dry seasons. Copyright (c) 2011 John Wiley & Sons, Ltd.
Genxu Wang - One of the best experts on this subject based on the ideXlab platform.
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bryophytes impact the fluxes of soil non carbon dioxide greenhouse gases in a subalpine Coniferous Forest
Biology and Fertility of Soils, 2020Co-Authors: Thomas H Deluca, Shouqin Sun, Jun Zhang, Genxu WangAbstract:Terrestrial bryophytes substantially regulate ecosystem processes in high latitude and high elevation ecosystems; however, the role of these plants in mediating soil emissions of non-CO2 greenhouse gases (GHGs) (N2O and CH4) in these ecosystems remains poorly understood. A removal experiment was conducted to investigate the influence of bryophytes on soil non-CO2 GHGs emission in a subalpine Coniferous Forest on the eastern edge of the Tibetan Plateau. Bryophyte removal decreased the average N2O emission rate, but did not significantly alter the CH4 flux rate. The cumulative amount of N2O emission and CH4 uptake was decreased by bryophyte removal. Compared to bryophyte-removal plots, soil in the control plots had higher concentrations of soil organic C (SOC), total N (TN), dissolved organic C (DOC), dissolved N (DN), and exchangeable NH4+. The control plots also had higher cumulative N2O emission and CH4 uptake compared to plots with bryophytes removed. Bryophyte-removal significantly changed the relationship between soil non-CO2 GHGs flux rates and soil water content, induced a linear decreasing relationship between the N2O emission rate and soil water content and a quadratic relationship between CH4 flux rate and soil water content in the bryophyte-removal plots. Results from this study indicate that bryophytes may regulate non-GHG emissions from subalpine Coniferous soils and demonstrate that in the presence of bryophytes, these soils may act as a greater N2O source and CH4 sink in southwestern China.
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soil warming and nitrogen deposition alter soil respiration microbial community structure and organic carbon composition in a Coniferous Forest on eastern tibetan plateau
Geoderma, 2019Co-Authors: Shouqin Sun, Thomas H Deluca, Jun Zhang, Genxu Wang, Wanze Zhu, Min DuanAbstract:Abstract Understanding the response of soil respiration (Rs) to future climate projections is critical for understanding feedbacks and developing effective mitigation strategies. We conducted a warming and N deposition manipulation experiment using a 2 × 2 full-factorial design to evaluate the interactive effects of soil warming and N deposition on Rs, microbial community composition and soil organic carbon (SOC) composition in a subalpine Coniferous Forest on the eastern slope of the Qinghai-Tibetan Plateau. Soil warming and N addition independently increased Rs and changed microbial community composition, resulting in a net increase in bacteria with N addition and an increase in protozoa with warming; but the interaction of these two factors proved to be antagonistic, resulting in a lower Rs and protozoa concentration in the combined warming and nitrogen addition (WN) treatment relative to the warming (W) treatment. The chemical structure of SOC changed with the treatments, with alkyl C increased with warming, aromatic C decreased with both warming and N addition, and the interaction of warming and N induced a lower O-alkyl C and a higher contribution of alkyl C to SOC. The negative correlation between Rs and aromatic C and the positive correlation between Rs and alkyl C and MBC indicates that the elevated CO2 emission under warming and N addition was related to the decomposition of aromatic C and the following relative accumulation of alkyl C. Our observations suggest that climate induced soil warming will likely increase soil CO2 emissions, but this effect could be largely offset by a simultaneous increase in N deposition in subalpine Coniferous Forests.
Teemu Kokkonen - One of the best experts on this subject based on the ideXlab platform.
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snow processes in a Forest clearing and in a Coniferous Forest
Journal of Hydrology, 2002Co-Authors: Harri Koivusalo, Teemu KokkonenAbstract:An energy balance approach is applied to simulate snow accumulation and melt in a Forest clearing and in a Coniferous Forest. The study site is located in southern Finland (60.1°N) where the winters are mild considering the high latitude. For Forest simulations the snow model is coupled with a procedure, which accounts for the effects of the canopy on the driving meteorological variables of the snow model. Model results are first validated against measured values of snow water equivalent and snow temperature in a Forested site and in an adjacent clearing. Subsequently differences in snow accumulation, snowmelt, and energy components contributing to snowmelt in open and Forested conditions are studied. Effect of the canopy on snow mass balance on the ground can be seen as higher accumulation and more intense snowmelt in the open. Due to these counteracting processes the results show little difference in the annual maximum of the snow water equivalent between the clearing and the Forest. The model results suggest that in mid-winter the main source of energy for snowmelt is sensible heat in the open, whereas both sensible heat and net radiation contribute equally to snowmelt in the Forest. Solar radiation intensity increases towards the spring, which causes net radiation to become dominant in both sites.
Makoto Tani - One of the best experts on this subject based on the ideXlab platform.
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seasonal and diurnal patterns of soil respiration in an evergreen Coniferous Forest evidence from six years of observation with automatic chambers
PLOS ONE, 2018Co-Authors: Naoki Makita, Yoshiko Kosugi, Ayaka Sakabe, Akito Kanazawa, Shinjiro Ohkubo, Makoto TaniAbstract:Soil respiration (Rs) plays a key role in the carbon balance of Forest ecosystems. There is growing evidence that Rs is strongly correlated with canopy photosynthesis; however, how Rs is linked to aboveground attributes at various phenological stages, on the seasonal and diurnal scale, remains unclear. Using an automated closed dynamic chamber system, we assessed the seasonal and diurnal patterns of Rs in a temperate evergreen Coniferous Forest from 2005 to 2010. High-frequency Rs rates followed seasonal soil temperature patterns but the relationship showed strong hysteresis. Predictions of Rs based on a temperature-response model underestimated the observed values from June to July and overestimated those from August to September and from January to April. The observed Rs was higher in early summer than in late summer and autumn despite similar soil temperatures. At a diurnal scale, the Rs pattern showed a hysteresis loop with the soil temperature trend during the seasons of high biological activity (June to October). In July and August, Rs declined after the morning peak from 0800 to 1400 h, although soil temperatures continued to increase. During that period, figure-eight-shaped diurnal Rs patterns were observed, suggesting that a midday decline in root physiological activity may have occurred in early summer. In September and October, Rs was higher in the morning than in the night despite consistently high soil temperatures. We have characterised the magnitude and pattern of seasonal and diurnal Rs in an evergreen Forest. We conclude that the temporal variability of Rs at high resolution is more related to seasons across the temperature dependence.
T. M. Ruuskanen - One of the best experts on this subject based on the ideXlab platform.
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Carbonyl compounds in boreal Coniferous Forest air in Hyytiälä, Southern Finland
Atmospheric Chemistry and Physics, 2004Co-Authors: H. Hellén, H. Hakola, A. Reissell, T. M. RuuskanenAbstract:A variety of C1-C12 carbonyl compounds were measured in the air of a boreal Coniferous Forest located in Hyytiälä, Southern Finland. 24-hour samples were collected during March and April in 2003 using DNPH (2,4-dinitrophenyl hydrazine) coated C18-cartridges and analyzed by liquid chromatography-mass spectrometry (LC-MS). Altogether 22 carbonyl compounds were quantified. The most abundant carbonyls were acetone (24-hour average 1340ng/m3), formaldehyde (480ng/m3) and acetaldehyde (360ng/m3). Concentrations of monoterpene reaction products nopinone (9ng/m3) and limona ketone (5ng/m3) were low compared to the most abundant low molecular weight carbonyls. Trajectory analysis showed that highest concentrations of carbonyls were measured in the air masses coming from the East and the lowest in the air masses cycled long time over Scandinavia. The total concentration of carbonyl compounds in Hyytiälä in March/April 2003 was much higher than the concentration of aromatic hydrocarbons and monoterpenes in April 2002. Scaling the concentrations against reactivity with the OH-radical showed, that in spite of relatively low ambient concentrations higher molecular weight aldehydes contribute significantly to the total OH-reactive mass of carbonyls. The impact of carbonyl compounds on OH-radical chemistry is important. Contribution of carbonyls as an OH sink is comparable to that of NO2 and higher than monoterpenes and aromatic hydrocarbons. Lifetimes of the measured carbonyls with respect to reactions with OH radicals, ozone (O3), and nitrate (NO3) radicals as well as photolysis were estimated. The main sink reactions for most of the carbonyl compounds in Hyytiälä in springtime are expected to be reactions with the OH radical and photolysis. For 6-methyl-5-hepten-2-one and limona ketone also reactions with ozone are important. The sources of carbonyl compounds are presently highly uncertain. Based on the comparisons with urban concentrations the direct anthropogenic emissions are not as important as secondary biogenic and anthropogenic sources or primary biogenic sources in Hyytiälä.
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Carbonyl compounds in boreal Coniferous Forest air in Hyytiälä, Southern Finland
Atmospheric Chemistry and Physics Discussions, 2004Co-Authors: H. Hellén, H. Hakola, A. Reissell, T. M. RuuskanenAbstract:A variety of C1-C12 carbonyl compounds were measured in the air of a boreal Coniferous Forest located in Hyytiälä, Southern Finland. 24-h samples were collected during March and April in 2003 using DNPH (2,4-dinitrophenyl hydrazine) coated C18-cartridges and analyzed by liquid chromatography-mass spectrometry (LC-MS). Altogether 22 carbonyl compounds were quantified. The most abundant carbonyls were acetone (24-h average 1340 ng/m3), formaldehyde (480 ng/m3) and acetaldehyde (360 ng/m3). In contrast, scaling of concentrations against reactivity with the hydroxyl (OH) radical significantly increased the contribution of larger aldehydes and ketones (e.g. decanal, octanal and 6-methyl-5-hepten-2-one). Concentrations of monoterpene reaction products nopinone (9 ng/m3) and limona ketone (5 ng/m3) were low compared to the most abundant low molecular weight carbonyls. The total concentration of carbonyl compounds in Hyytiälä in April/March 2003 was much higher than the concentration of aromatic hydrocarbons and monoterpenes in April 2002. Lifetimes of the measured carbonyls with respect to reactions with OH radicals, ozone (O3), and nitrate (NO3) radicals as well as photolysis were estimated. The main sinks for most of the carbonyl compounds in Hyytiälä in springtime are expected to be reactions with the OH radical and photolysis. For 6-methyl-5-hepten-2-one and limona ketone also reactions with ozone are important. The sources of carbonyl compounds are presently highly uncertain. Due to the relatively short lifetimes of aldehydes and ketones, secondary biogenic and anthropogenic sources, that is oxidation of volatile organic compounds, and primary biogenic sources are expected to dominate in Hyytiälä.