温室气体及其生态效应

研竞分析了CO₂、CH₄、N₂O、SO₂、CFCs等主要温室气体的生态效应,结果表明其生态效应与其性质及浓度有关,提出了缓解温室气体释放的有效对策。     

用树轮δ13C重建过去300年大气CO2浓度

The annual series of δ13C were measured in tree rings of three Cryptomeria fortunei disks （OF-1, OF-2, and OF- 3） collected from West Tianmu Mountain, Zhejiang Province, China, according to cross-dating tree ring ages. There was no obvious decreasing trend of the δ13C annual time series of CF-2 before 1835. However, from 1835 to 1982 the three tree ring δ13C annual series exhibited similar decreasing trends that were significantly （P ≤ 0.001） correlated. The distribution characteristics of a scatter diagram between estimated δ13C series of CF-2 from modeling and the atmospheric CO2 concentration extracted from the Law Dome ice core from 1840 to 1978 were analyzed and a curvilinear regression equation for reconstructing atmospheric CO2 concentration was established with R2 = 0.98. Also, a test of independent samples indicated that between 1685 and 1839 the reconstructed atmospheric CO2 concentration .using the δ13C series of CF-2 had a close relationship with the Law Dome and Siple ice cores, with a standard deviation of 1.98. The general increasing trend of the reconstructed atmospheric CO2 concentration closely reflected the 10ng-term variation of atmospheric CO2 concentration recorded both before and after the Industrial Revolution. Between 1685 and 1840 the evaluated atmospheric CO2 concentration was stable, but after 1840 it exhibited a rapid increase. Given a longer δ13C annual time series of tree rings, it was feasible to rebuild a representative time series to describe the atmospheric CO2 concentration for an earlier period and for years that were not in the ice core record.     

CO2浓度对金针菇生长发育的影响

在人工控制环境条件下研究了CO2浓度对金针菇（Flammulina velutipes）生长发育的影响结果表明,金针菇菌丝正常生长所要求的适宜CO2浓度为261.7-2930.5μmol/L;金针菇子实体原基形成随CO2浓度升高明显受到抑制,所要求的适宜CO2浓度范围为12.3-60μmol/L;菇蕾形成后为获得优质高产金针菇,应提高环境内CO2浓度,并控制在210－600μmol/L范围内。     

高CO2浓度下羊草对土壤干旱胁迫的响应

在高CO2浓度下羊草对土壤干旱胁迫响应的人工模拟试验分析表明,CO2浓度升高对羊草具有“施肥”效应,羊草生物量增加20％以上,光合速率提高50％左右,气孔阻力增大,蒸腾速率下降,水分利用效率提高,土壤干旱胁迫对羊草的影响为负效应,与此相反,高CO2浓度下发生土壤干旱胁迫一定程度抑制了CO2的施肥效应。     

GREENHOUSE GAS EMISSIONS FROM AN ALKALINE SALINE SOIL CULTIVATED WITH MAIZE (ZEA MAYS L.) AND AMENDED WITH ANAEROBICALLY DIGESTED COW MANURE: A GREENHOUSE EXPERIMENT

Sludge derived from cow manure anaerobically digested to produce biogas (methane; CH₄) was applied to maize (Zea mays L.) cultivated in a nutrient-low, alkaline, saline soil with electrolytic conductivity 9.4 dS m^?1 and pH 9.3. Carbon dioxide (CO₂) emission increased 3.1 times when sludge was applied to soil, 1.6 times when cultivated with maize and 3.5 times in sludge-amended maize cultivated soil compared to the unamended uncultivated soil (1.51 mg C kg^?1 soil day^?1). Nitrous oxide (N₂O) emission from unamended soil was -0.0004 μg nitrogen (N) kg^?1 soil day^?1 and similar from soil cultivated with maize (0.27 μg N kg^?1 soil day^?1). Application of sludge increased the N₂O emission to 4.59 μg N kg^?1 soil day^?1, but cultivating this soil reduced it to 2.42 μg N kg^?1 soil day^?1. It was found that application of anaerobic digested cow manure stimulated maize development in an alkaline saline soil and increased emissions of CO₂ and N₂O.     

盐碱地土壤：氧化亚氮和二氧化碳排放的潜在来源？

Increasing salt-affected agricultural land due to low precipitation,high surface evaporation,irrigation with saline water,and poor cultural practices has triggered the interest to understand the influence of salt on nitrous oxide(N_2O) and carbon dioxide(CO_2)emissions from soil.Three soils with varying electrical conductivity of saturated paste extract(EC_e)(0.44-7.20 dS m~(-1)) and sodium adsorption ratio of saturated paste extract(SARe)(1.0-27.7),two saline-sodic soils(S2 and S3) and a non-saline,non-sodic soil(S1),were incubated at moisture levels of 40%,60%,and 80%water-filled pore space(WFPS) for 30 d,with or without nitrogen(N)fertilizer addition(urea at 525 μg g~(-1) soil).Evolving CO_2 and N2 O were estimated by analyzing the collected gas samples during the incubation period.Across all moisture and N levels,the cumulative N_2O emissions increased significantly by 39.8%and 42.4%in S2 and S3,respectively,compared to S1.The cumulative CO_2 emission from the three soils did not differ significantly as a result of the complex interactions of salinity and sodicity.Moisture had no significant effect on N_2O emissions,but cumulative CO_2 emissions increased significantly with an increase in moisture.Addition of N significantly increased cumulative N_2O and CO_2 emissions.These showed that saline-sodic soils can be a significant contributor of N_2O to the environment compared to non-saline,non-sodic soils.The application of N fertilizer,irrigation,and precipitation may potentially increase greenhouse gas(N2O and CO_2) releases from saline-sodic soils.     

红壤交换性钙、镁和钾的分布及施肥对其影响

A leaching experiment was Carried out with repacked soil columns in laboratory to study the leaching process of a red soil derived from sandstone as affected by various fertilization practices.The treatments were CK(as a control),CaCO3,CaSO4,MgCO3,Ca(H2PO4)2,Urea,KCl,Multiple(a mixture of the above mentioned fertilizers) and KNO3,The fertilizers were added to the bare surface of the soil columns,and then the columns were leached with 120 mL deionized water daily through perstaltic pumps over a period of 92 days,At the end of leaching process,soils were sampled from different depths of the soil profiles ,i.o.,of 92 days,At the end of leaching process,soils were sampled from different depths of the soil profiles,I.e.0-5cm,5-10cm,10-20cm,20-40cm,and 40-60cm,The results showed when applying Ca,Mg,and K to the bare surface of the soil columns,exchangeable Ca^2 ,Mg^2 ,and K^ in the upper layer of the soil profile increased correspondingly,with an extent depending mainly on the application rates of Ca,Mg,and K and showing a downward trend,CaCO3,CaSO4,MgCO3,and Ca(H2PO4)2 treatments had scarcely and effect on movement of exchangeable K^ ,while CaCO3,and CaSO4 treatments singnificantly promoted the downward movement of exchangealble Mg^2 although these two treatments had no obvious effect on leaching losses of Mg,The fact that under Urea treatment,exchangeable Ca^2 and Mg^2 ,were higher as compared to CK treatment showed urea could prevent leaching of exchangeable Ca^2 and Mg^2 ,the obvious downward movement of exchangeable Ca^2 and Mg^2 was noticed in KCl treatment ,In Multiple treatment,the downward movement of exchangeable Ca^2 and Mg^2 was evident,while that of K^ was less evident,Application of KNO3 strongly promoted the downward movement of exchangeable Ca^2 and Mg^2 in the soil profile.     

Enchytraeids in a changing climate: A mini-review

The climate is undergoing rapid changes with rising atmospheric CO₂ concentration, increasing temperatures and changes in the hydrological regimes resulting in more frequent and intense drought periods. These three climate change factors will, separately and in combination, affect the biotic and abiotic components of soil communities. This paper reviews the impact of climate change on field communities of enchytraeids with special emphasis on Cognettia sphagnetorum because most relevant studies have involved this species. C. sphagnetorum prefers cold and wet environments and several studies suggest that reductions of soil moisture may have dramatic consequences for C. sphagnetorum and other enchytraeid species. Effects of changing temperatures are less clear partly because thermal conditions influence soil moisture, which complicate the predictions of the outcome from such changes. The predicted increasing annual mean temperature may be stimulating and expand the season for growth and reproduction of enchytraeids; on the other hand, an increased frequency of extreme weather events, with heat waves during summer and bare soil freezes during autumn and spring, may occasionally cause severe mortality. Stimulating effects of increased atmospheric CO₂ have been observed, perhaps due to increased food availability via root and litter production. However, effects of CO₂ are also influenced by moisture and temperature. Generally, there is a lack of research looking into the complicated interactions between various climate change factors, and little is known about the potential of enchytraeids to adapt to a changing climate. Existing data suggest that C. sphagnetorum is not capable of adapting to a drier climate, thus, a decline in abundance and distribution of this species is possible. Since enchytraeids are of ecological significance in some types of habitats, a reduction may result in serious disruption in the functioning of these decomposer communities.     

液面上部气体的置换对土壤厌氧培养下的N2O和CO2排放的影响

To study effect of C2H2 and change of headspace gas on N2O emission,denitrification,as well as CO2 emission,slurries of an agricultural soil were anaerobically incubated for 7 days at 25℃.Both N2O reduction and CO2 emissions were inhibited by the addition of 100 mL L^-1 of C2H2.However,the inhibition to CO2 emission was alleviated by the replacement of headspace gas,and the N2O emission was enhanced by the replacement.Acetylene disappeared evidently from the soil slurries during the incubation.Consequently results obtained from the traditional C2H2 blocking technique for determination of denitrifcation rate,especially in a long-time incubation,should be explained with care because of its side effect exsting in the incubation environments without change of headspace gas.To reduce the possible side effect on the processes other than denitrification ,it is suggested that headspace gas should be replaced several times during a long-time incubation.     

Soil CO2 efflux vs. soil respiration: Implications for flux models

In the long term, all CO₂ produced in the soil must be emitted by the surface and soil CO₂ efflux (FCO₂) must correspond to soil respiration (R_soil). In the short term, however, the efflux can deviate from the instantaneous soil respiration, if the amount of CO₂ stored in the soil pore-space (SCO₂) is changing. We measured FCO₂ continuously for one year using an automated chamber system. Simultaneously, vertical soil profiles of CO₂ concentration, moisture, and temperature were measured in order to assess the changes in the amount of CO₂ stored in the soil. R_soil was calculated as the sum of the rate of change of the CO₂ storage over time and FCO₂. The experiment was split into a warm and a cold season. The dependency of soil respiration and soil efflux on soil temperature and on soil moisture was analyzed separately. Only the moisture-driven model of the warm season was significantly different for FCO₂ and R_soil. At our site, a moisture-driven soil-respiration model derived from CO₂ efflux data would underestimate the importance of soil moisture. This effect can be attributed to a temporary storage of CO₂ in the soil pore-space after rainfalls where up to 40% of the respired CO₂ were stored.     

Rhizodeposition-induced decomposition increases N availability to wild and cultivated wheat genotypes under elevated CO2

Elevated CO₂ may increase nutrient availability in the rhizosphere by stimulating N release from recalcitrant soil organic matter (SOM) pools through enhanced rhizodeposition. We aimed to elucidate how CO₂-induced increases in rhizodeposition affect N release from recalcitrant SOM, and how wild versus cultivated genotypes of wheat mediated differential responses in soil N cycling under elevated CO₂. To quantify root-derived soil carbon (C) input and release of N from stable SOM pools, plants were grown for 1 month in microcosms, exposed to ¹³C labeling at ambient (392 μmol mol⁻¹) and elevated (792 μmol mol⁻¹) CO₂ concentrations, in soil containing ¹⁵N predominantly incorporated into recalcitrant SOM pools. Decomposition of stable soil C increased by 43%, root-derived soil C increased by 59%, and microbial-¹³C was enhanced by 50% under elevated compared to ambient CO₂. Concurrently, plant ¹⁵N uptake increased (+7%) under elevated CO₂ while ¹⁵N contents in the microbial biomass and mineral N pool decreased. Wild genotypes allocated more C to their roots, while cultivated genotypes allocated more C to their shoots under ambient and elevated CO₂. This led to increased stable C decomposition, but not to increased N acquisition for the wild genotypes. Data suggest that increased rhizodeposition under elevated CO₂ can stimulate mineralization of N from recalcitrant SOM pools and that contrasting C allocation patterns cannot fully explain plant mediated differential responses in soil N cycling to elevated CO₂.