Abies fabri is a typical subalpine dark coniferous forest in southwestern China. Air temperature increases more at high elevation areas than that at low elevation areas in mountainous regions,and climate change ratio ...Abies fabri is a typical subalpine dark coniferous forest in southwestern China. Air temperature increases more at high elevation areas than that at low elevation areas in mountainous regions,and climate change ratio is also uneven in different seasons. Carbon gain and the response of water use efficiency(WUE) to annual and seasonal increases in temperature with or without CO_2 fertilization were simulated in Abies fabri using the atmospheric-vegetation interaction model(AVIM2). Four future climate scenarios(RCP2.6,RCP4.5,RCP6.0 and RCP8.5) from the Coupled Model Intercomparison Project Phase 5(CMIP5) were selectively investigated. The results showed that warmer temperatures have negative effects on gross primary production(GPP) and net primary production(NPP) in growing seasons and positive effects in dormant seasons due to the variation in the leaf area index. Warmer temperatures tend to generate lower canopy WUE and higher ecosystem WUE in Abies fabri. However,warmer temperature together with rising CO_2 concentrations significantlyincrease the GPP and NPP in both growing and dormant seasons and enhance WUE in annual and dormant seasons because of the higher leaf area index(LAI) and soil temperature. The comparison of the simulated results with and without CO_2 fertilization shows that CO_2 has the potential to partially alleviate the adverse effects of climate warming on carbon gain and WUE in subalpine coniferous forests.展开更多
Soil microbial biomass is critical for biogeochemical cycling and serves as precursor for carbon(C)sequestration.The anthropogenic nitrogen(N)input has profoundly changed the pool of soil microbial biomass.However,tra...Soil microbial biomass is critical for biogeochemical cycling and serves as precursor for carbon(C)sequestration.The anthropogenic nitrogen(N)input has profoundly changed the pool of soil microbial biomass.However,traditional N deposition simulation experiments have been exclusively conducted through infrequent N addition,which may have caused biased effects on soil microbial biomass compared with those under the natural and continuous N deposition.Convincing data are still scarce about how the different N addition frequencies affect soil microbial biomass.By independently manipulating the frequencies(2 times vs.12 times N addition yr^(–1))and the rates(0–50 g N m^(−2) yr^(−1))of N addition,our study aimed to examine the response of soil microbial biomass C(MBC)to different N addition frequencies with increasing N addition rates.Soil MBC gradually decreased with increasing N addition rates under both N addition frequencies,while the soil MBC decreased more at low frequency of N addition,suggesting that traditional studies have possibly overestimated the effects of N deposition on soil microbial biomass.The greater soil microbial biomass loss with low N frequency resulted from the intensifed soil acidifcation,higher soil inorganic N,stronger soil C and N imbalance,less net primary production allocated to belowground and lower fungi to bacteria ratio.To reliably predict the effects of atmospheric N deposition on soil microbial functioning and C cycling of grassland ecosystems in future studies,it is necessary to employ both the dosage and the frequency of N addition.展开更多
基金supported by the Natural Science Foundation of China (No.41401044 and No.41310013)the key research projects of frontier sciences CAS (QYZDJ-SSW-DQC006)+1 种基金the Chinese Academy of Science (‘West Star’ project)the CAS/SAFEA international partnership program for creative research teams (KZZD-EW-TZ-06)
文摘Abies fabri is a typical subalpine dark coniferous forest in southwestern China. Air temperature increases more at high elevation areas than that at low elevation areas in mountainous regions,and climate change ratio is also uneven in different seasons. Carbon gain and the response of water use efficiency(WUE) to annual and seasonal increases in temperature with or without CO_2 fertilization were simulated in Abies fabri using the atmospheric-vegetation interaction model(AVIM2). Four future climate scenarios(RCP2.6,RCP4.5,RCP6.0 and RCP8.5) from the Coupled Model Intercomparison Project Phase 5(CMIP5) were selectively investigated. The results showed that warmer temperatures have negative effects on gross primary production(GPP) and net primary production(NPP) in growing seasons and positive effects in dormant seasons due to the variation in the leaf area index. Warmer temperatures tend to generate lower canopy WUE and higher ecosystem WUE in Abies fabri. However,warmer temperature together with rising CO_2 concentrations significantlyincrease the GPP and NPP in both growing and dormant seasons and enhance WUE in annual and dormant seasons because of the higher leaf area index(LAI) and soil temperature. The comparison of the simulated results with and without CO_2 fertilization shows that CO_2 has the potential to partially alleviate the adverse effects of climate warming on carbon gain and WUE in subalpine coniferous forests.
基金supported by the National Natural Science Foundation of China(42130515 and31770506)the Open Foundation of the State Key Laboratory of Urban and Regional Ecology of Chinathe Open Foundation of the State Key Laboratory of Grassland Agro-ecosystems of China。
文摘Soil microbial biomass is critical for biogeochemical cycling and serves as precursor for carbon(C)sequestration.The anthropogenic nitrogen(N)input has profoundly changed the pool of soil microbial biomass.However,traditional N deposition simulation experiments have been exclusively conducted through infrequent N addition,which may have caused biased effects on soil microbial biomass compared with those under the natural and continuous N deposition.Convincing data are still scarce about how the different N addition frequencies affect soil microbial biomass.By independently manipulating the frequencies(2 times vs.12 times N addition yr^(–1))and the rates(0–50 g N m^(−2) yr^(−1))of N addition,our study aimed to examine the response of soil microbial biomass C(MBC)to different N addition frequencies with increasing N addition rates.Soil MBC gradually decreased with increasing N addition rates under both N addition frequencies,while the soil MBC decreased more at low frequency of N addition,suggesting that traditional studies have possibly overestimated the effects of N deposition on soil microbial biomass.The greater soil microbial biomass loss with low N frequency resulted from the intensifed soil acidifcation,higher soil inorganic N,stronger soil C and N imbalance,less net primary production allocated to belowground and lower fungi to bacteria ratio.To reliably predict the effects of atmospheric N deposition on soil microbial functioning and C cycling of grassland ecosystems in future studies,it is necessary to employ both the dosage and the frequency of N addition.
