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Regional coupled c-N-H2O cycle processes and associated driving mechanisms

Science china Earth Sciences 2020年第9期63卷 1227-1236页

作者： Yang GAO Gui-Rui YU Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China college of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China

From a molecular level to an ecosystem scale,different coupling mechanisms take place during coupled carbonnitrogen-water(c-N-H2O)cycle,of which essential are water flux and related biogeochemical processes through physicochemical reactions associated with terrestrial and aquatic ecosystems.Meanwhile,regional coupled c-N-H2O cycle will subsequently impact regional gross primary productivity(GPP)and c and N exchanges during air-water interactions that occur downstream of watersheds.This study aimed to first synthetically analyze the regional dynamics of c,N and H2O cycles in ecosystems and determine their interactional relationships;second,to specify regional c-N-H2O coupled relationships of ecosystems and their theoretical ecological principles;third,to classify coupled regional response and adaptation of the c-N-H2O cycle to climatic and environmental changes under anthropogenic activities,providing a theoretical basis to fully understand and make adjustments to interactional c,N and H2O cycling relationships at different ecosystem scales and under associated coupling processes.

关键词： Regional c-N-H2O cycle coupled relationship c cycle N cycle Water cycle Driving mechanisms

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A spatial-explicit dynamic vegetation model that couples carbon,water,and nitrogen processes for arid and semiarid ecosystems

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Journal of Arid Land 2013年第1期5卷 102-117页

作者： chi ZHANG chaoFan LI Xi cHEN GePing LUO LongHui LI XiaoYu LI Yan YAN Hua SHAO State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China University of the chinese Academy of Sciences Beijing 100049 China

Arid and semiarid ecosystems, or dryland, are important to global biogeochemical cycles. Dryland＇s community structure and vegetation dynamics as well as biogeochemical cycles are sensitive to changes in climate and atmospheric composition. Vegetation dynamic models has been applied in global change studies, but the com- plex interactions among the carbon （c）, water, and nitrogen （N） cycles have not been adequately addressed in the current models. In this study, a process-based vegetation dynamic model was developed to study the responses of dryland ecosystems to environmental changes, emphasizing on the interactions among the c, water, and N proc- esses. To address the interactions between the c and water processes, it not only considers the effects of annual precipitation on vegetation distribution and soil moisture on organic matter （SOM） decomposition, but also explicitly models root competition for water and the water compensation processes. To address the interactions between c and N processes, it models the soil inorganic mater processes, such as N mineralization/immobilization, denitrifica- tion/nitrification, and N leaching, as well as the root competition for soil N. The model was parameterized for major plant functional types and evaluated against field observations.

关键词： process-based model arid ecosystem c cycle vegetation dynamics

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Larger floods reduce soil cO_(2)efflux during the post-flooding phase in seasonally flooded forests of Western Amazonia

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Pedosphere 2021年第2期31卷 342-352页

作者： Emma M.DOcHERTY Andrew D.THOMAS Department of Geography and Earth Sciences Aberystwyth UniversityAberystwyth SY233DB(UK) School of Geography University of LeedsLeeds LS29JT(UK)

Seasonally flooded várzea forests of Western Amazonia are one of the most productive and biodiverse wetland forests in the world.However,data on their soil cO_(2)emissions,soil organic matter decomposition rates,and soil c stocks are scarce.This is a concern because hydrological changes are predicted to lead to increases in the height,extent,and duration of seasonal floods,which are likely to have a significant effect on soil c stocks and fluxes.However,with no empirical data,the impact of altered flood regimes on várzea soil c cycles remains uncertain.This study quantified the effects of maximum annual flood height and soil moisture on soil cO_(2)efflux rate(R_(s))and soil organic matter decomposition rate(k)in the várzea forests of Pacaya Samiria National Reserve,Peru.The study was conducted between May and August 2017.The results showed that R_(s)(10.6–182.7 mg c m^(-2)h^(-1))and k(0.016–0.078)varied between and within sites,and were considerably lower than the values reported for other tropical forests.In addition,R_(s)was negatively affected by flood height(Pcreased with decreasing river levels post flooding(Pcontrast,k was not affected by any of the above-mentioned factors.Soil moisture was the dominant factor influencing R_(s),and it was significantly affected by maximum flood height,even after the floods had subsided(Pconsequently,we concluded that larger floods will likely lead to reduced R_(s),whilst k could remain unchanged but with decomposition processes becoming more anaerobic.

关键词： c cycle climate change greenhouse gas soil cO_(2)emissions soil moisture soil organic matter decomposition rate tropical forest

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Short-term effects of maize residue biochar on kinetic and thermodynamic parameters of soil β-glucosidase

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Biochar 2019年第2期1卷 213-227页

作者： Fayez Raiesi Allahyar Khadem Department of Soil Science and Engineering Faculty of AgricultureShahrekord UniversityP.O.Box 115ShahrekordIran

Soil β-glucosidase (BG), the rate-limiting enzyme in the final step of cellulose hydrolysis, plays a key role in microbial metabolism, carbon (c) cycling and sequestration in terrestrial ecosystems. Biochar application is known to affect soil BG activity;however, most of the biochar studies have focused on the potential activity of BG, and it is not clear how biochar influences the kinetic and thermodynamic behavior of BG in the soil. The objective of this study was to investigate the effect of maize residue biochar on soil BG kinetic and thermodynamic parameters. Soil BG kinetic (V_(max) and K_(m)) and ther-modynamic (E_(a), ΔH_(a) and Q_(10)) parameters were determined within soils (clayey and sandy loam soils) amended with either maize residue (as positive control) or its biochar (600℃) at 0.5 and 1.0% ratios (w/w), and the mixtures were incubated for 90 days. BG showed an increase in potential enzymatic activity (81%), enzyme concentration (higher V_(max) value) (25%) and substrate affinity (lower K_(m) value) (32%) in the biochar-amended sandy loam soil only at high addition rates compared with the control, and an increase by about 86% of the catalytic efficiency (V_(max)/K_(m)). In the clayey soil, biochar addition decreased potential BG activity (by 10-29%), increased the V_(max) value (by 20-25%) and had no impact on enzyme-substrate binding affinity, but still increased the catalytic efficiency by 47-72%. Adsorption of soil BG by biochar particles did not affect the catalytic efficiency in the soil. Generally, application of maize residue biochar to the soil decreased the E_(a), ΔH_(a) and Q_(10) values of BG compared with the negative controls at both biochar rates in the light-textured soil and only at low biochar rate in heavy-textured soil. The direction and magnitude of BG responses (activity, kinetics, and thermodynamics) to biochar were more related to the soil characteristics. Biochar would increase soil BG thermal stability and decrease its sensitivity to increasing temperature and global warmin

关键词： Biochar β-Glucosidase behavior Thermal sensitivity Enzyme adsorption Soil texture c cycle

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