Climate change impacts soil nitrogen, influencing plant responses to elevated atmospheric [CO2]. Understanding the interaction between nitrogen supply and elevated [CO2] is crucial for predicting plant future performa...Climate change impacts soil nitrogen, influencing plant responses to elevated atmospheric [CO2]. Understanding the interaction between nitrogen supply and elevated [CO2] is crucial for predicting plant future performance. This study examined the interactive effects of elevated [CO2] and nitrogen supply on the eco-physiological performance of yellow birch. Seedlings were exposed to two [CO2] levels and five nitrogen supply levels for 4 months. Growth parameters such as seedling height and root collar diameter increased with higher nitrogen supply and elevated [CO2], while specific leaf area decreased. [CO2] elevation and increasing nitrogen supply also increased the total and stem, and leaf biomass. The elevated [CO2] increased the stem mass ratio but decreased the root-to-shoot ratio and root mass ratio. However, decreases in nitrogen supply increased root mass ratio and root-to-shoot ratio. The elevated [CO2] increased the maximum rate of Rubisco carboxylation (Vcmax) and photosynthetic electron transport (Jmax), but the effect on Jmax was statistically significant only at the two highest nitrogen supply levels. The results indicate that yellow birch may increase photosynthetic capacity, biomass, and growth in the future when [CO2] is higher.展开更多
Safe and economical disposal of paper mill sludge is a key consideration for forest products industry. A study was conducted to examine the effects of amendments of sludge and nutrients on soil surface CO2 flux （Rs）...Safe and economical disposal of paper mill sludge is a key consideration for forest products industry. A study was conducted to examine the effects of amendments of sludge and nutrients on soil surface CO2 flux （Rs） in northern hardwood forests and to quantify the relationship among Rs, soil temperature, and moisture in these stands. The experiment was a randomized complete block design that included sludge-amended, fertilized, and control treatments in sugar maple （Acer saccharum Marsh） dominated hardwood forests in the Upper Peninsula of Michigan, USA. Results showed that Rs was positively correlated to soil temperature （R^2 = 0.80, p 〈 0.001）, but was poorly correlated to soil moisture. Soil moisture positively affected the Rs only in the sludge-amended treatment. The Rs was significantly greater in the sludge-amended treatment than in the fertilized （p = 0.033） and the control （p = 0.048） treatments. The maximum Rs in the sludge-amended treatment was 8.8 μmol CO2 · m^ 2. s^-1, 91% and 126% greater than those in the fertilized （4.6 μmol CO2 · m^-2· s^-1） and control （3.9 μmol CO2· m^- 2· s^-1） treatments, respectively. The Rs did not differ significantly between the fertilized and control treatments. The difference in Rs between sludge-amended and the other treatments decreased with time following treatment.展开更多
The forest ecosystem plays an important role in the global carbon cycling. A study was conducted to evaluate soil CO2 flux and its seasonal and diurnal variation with the air and soil temperatures by using static clos...The forest ecosystem plays an important role in the global carbon cycling. A study was conducted to evaluate soil CO2 flux and its seasonal and diurnal variation with the air and soil temperatures by using static closed chamber technique in a typical broad-leaved/Korean pine mixed forest area on the northern slope of Changbai Mountain, Jilin Province, China. The experiment was carried out through the day and night in the growing season (from June to September) in situ and sample gas was analyzed by a gas chromatograph. Results showed that the forest floor was a large net source of carbon, and soil CO2 fluxes had an obvi-ous law of seasonal and diel variation. The soil CO2 flux of broad-leaved/Korean pine mixed forest was in the range of 0.302.42 mmol穖-2穝-1 with the mean value of 0.98 mmol穖-2穝-1. An examination on the seasonal pattern of soil CO2 emission suggested that the variability in soil CO2 flux could be correlated with variations in soil temperature, and the maximum of mean CO2 flux occurred in July ((1.27±23%) mmol穖-2穝-1) and the minimum was in September ((0.50±28%) mmol穖-2穝-1). The fluctuations in diel soil CO2 flux were also correlated with changes in soil temperature; however, there existed a factor for a time lag. Soil CO2 flux from the forest floor was strongly related to soil temperature and had the highest correlation with temperature at 6-cm depth of soil. Q10 values based on air temperature and soil temperature of different soil depths were at the ranges of 2.09–3.40.展开更多
Middle-sized chambers (40cmx40cmx20 cm) and an infrared gas analyzer (IRGA) were used for the measurement of net photosynthesis of the grass layer and soil CO2 evolution, in Quercus liaotungensis Koidz. forest, which ...Middle-sized chambers (40cmx40cmx20 cm) and an infrared gas analyzer (IRGA) were used for the measurement of net photosynthesis of the grass layer and soil CO2 evolution, in Quercus liaotungensis Koidz. forest, which is a typical temperate forest ecosystem in the mountainous areas of Beijing. Changes of CO2 concentrations in both the atmosphere (2m above canopy) and the forest canopy (2m below the top of the canopy) together with those of net photosynthesis and soil CO2 evolution were also examined, in order to find the characteristics of CO2 exchange between the different components of the temperate forest ecosystem and the atmosphere. Atmospheric CO2 averaged (323+10) and (330+1) mol mol-1 respectively in summer and autumn. During the 24-hour measurements, large differences as much as -46 and -61 mol mol-1 respectively in the atmosphere and forest were found. Net photosynthesis of the grass layer in summer was (2. 59 9+ 1.05) mol CO2 m-2 S-1, two times of that in autumn, (1.31+0.39) mol CO2 s-1 In summer, there was much more CO2 evolved from soil than in autumn, averaging (5.18+0.75) mol CO2 m-2 s-1 and (1.96 + 0.57) (mol CO2 m-2 s-1, respectively. A significant correlation was found between soil CO2 evolution and ground temperature, with F =-0.864 2+0.310 1X,r=0.7164, P<0.001 (n=117). Both the minimal atmospheric CO2 level and the maximum net photosynthesis occurred around 14:00; and an increase in atmospheric CO2 and of soil CO2 evolution during night times were also found to be remarkable.展开更多
The temperature change and rate of CO2 change are correlated with a time lag, as reported in a previous paper. The correlation was investigated by calculating a correlation coefficient r of these changes for selected ...The temperature change and rate of CO2 change are correlated with a time lag, as reported in a previous paper. The correlation was investigated by calculating a correlation coefficient r of these changes for selected ENSO events in this study. Annual periodical increases and decreases in the CO2 concentration were considered, with a regular pattern of minimum values in August and maximum values in May each year. An increased deviation in CO2 and temperature was found in response to the occurrence of El Niño, but the increase in CO2 lagged behind the change in temperature by 5 months. This pattern was not observed for La Niña events. An increase in global CO2 emissions and a subsequent increase in global temperature proposed by IPCC were not observed, but an increase in global temperature, an increase in soil respiration, and a subsequent increase in global CO2 emissions were noticed. This natural process can be clearly detected during periods of increasing temperature specifically during El Niño events. The results cast strong doubts that anthropogenic CO2 is the cause of global warming.展开更多
Changes in CO2 and temperature are correlated, but it is difficult to observe which is the cause and which is the effect. The release of CO2 dissolved in the ocean into the atmosphere depends on the atmospheric temper...Changes in CO2 and temperature are correlated, but it is difficult to observe which is the cause and which is the effect. The release of CO2 dissolved in the ocean into the atmosphere depends on the atmospheric temperature. However, examining the relationship between changes in CO2 caused by other phenomena and temperature is difficult. Studies of soil respiration (Rs) since the late 20th century have shown that CO2 emissions from soil respiration (Rs) are overwhelmingly greater than CO2 emissions from fossil fuel combustion. This is also noted in the IPCC carbon budget assessment. In this paper, the dependences of Rs on temperature, time, latitude, precipitation, seasons, etc., were investigated using the latest NASA database. The changes in temperature and Rs correlated well. There is also a good correlation between Rs and CO2 generation. Therefore, an increase in temperature results in an increase in CO2. On the other hand, there is no evidence other than model calculations that an increase in anthropogenic CO2 is mainly linked to a rise in temperature. The idea that global warming is caused by anthropogenic CO2 production is still a hypothesis. For these reasons, the relationship between global warming and anthropogenic CO2 should be reconsidered based on physical evidence without preconceptions. .展开更多
As a conventional farming practice, tillage has lasted for thousands of years in Loess Plateau, China. Although recent studies show that tillage is a prominent culprit to soil carbon loss in croplands, few studies hav...As a conventional farming practice, tillage has lasted for thousands of years in Loess Plateau, China. Although recent studies show that tillage is a prominent culprit to soil carbon loss in croplands, few studies have investigated the influences of tillage on the responses of soil CO2 efflux （SCE） to soil temperature and moisture. Using a multi-channel automated CO2 efflux chamber system, we measured SCE in situ continuously before and after the conventional tillage in a rain fed wheat field of Loess Plateau, China. The changes in soil temperature and moisture sensitivities of SCE, denoted by the Q10 value and linear regression slope respectively, were compared in the same range of soil temperature and moisture before and after the tillage. The results showed that, after the tillage, SCE increased by 1.2-2.2 times; the soil temperature sensitivity increased by 36.1%-37.5%; and the soil moisture sensitivity increased by 140%-166%. Thus, the tillage-induced increase in SCE might partially be attributed to the increases in temperature and moisture sensitivity of SCE.展开更多
【目的】研究稻田生态系统中土壤钙、镁元素生物地球化学循环对长期大气CO2浓度升高的响应。【方法】利用中国稻田FACE(free air carbon-dioxide enrichment)试验平台,包括Ambient(对照,自由大气CO2浓度约为370μmol·mol-1)和FACE...【目的】研究稻田生态系统中土壤钙、镁元素生物地球化学循环对长期大气CO2浓度升高的响应。【方法】利用中国稻田FACE(free air carbon-dioxide enrichment)试验平台,包括Ambient(对照,自由大气CO2浓度约为370μmol·mol-1)和FACE(比对照大气CO2浓度高200μmol·mol-1)2个试验处理,在2004、2005和2007年稻季不同生育期原位采集5cm和15cm处土壤溶液并测定其中Ca、Mg浓度。【结果】在2004、2005和2007年,FACE处理5cm处土壤溶液Ca浓度分别是对照处理的125%、106%和72%,Mg浓度分别是对照处理的115%、104%和75%;FACE处理15cm处与5cm处土壤溶液Ca浓度的比值在2004、2005和2007年分别是对照处理的71%、114%和180%,Mg的比值分别是对照的74%、104%和159%;2007年FACE处理0-15cm耕层土壤溶液Ca、Mg浓度分别比对照处理低6.8%和4.6%。【结论】连续大气CO2浓度升高可改变土壤溶液中Ca、Mg元素在不同深度耕层的分布,提高15cm处与5cm处土壤溶液Ca、Mg浓度的比值,且这种影响存在一定的累积效应。稻田生态系统Ca、Mg循环对长期大气CO2浓度升高的响应值得深入研究。展开更多
文摘Climate change impacts soil nitrogen, influencing plant responses to elevated atmospheric [CO2]. Understanding the interaction between nitrogen supply and elevated [CO2] is crucial for predicting plant future performance. This study examined the interactive effects of elevated [CO2] and nitrogen supply on the eco-physiological performance of yellow birch. Seedlings were exposed to two [CO2] levels and five nitrogen supply levels for 4 months. Growth parameters such as seedling height and root collar diameter increased with higher nitrogen supply and elevated [CO2], while specific leaf area decreased. [CO2] elevation and increasing nitrogen supply also increased the total and stem, and leaf biomass. The elevated [CO2] increased the stem mass ratio but decreased the root-to-shoot ratio and root mass ratio. However, decreases in nitrogen supply increased root mass ratio and root-to-shoot ratio. The elevated [CO2] increased the maximum rate of Rubisco carboxylation (Vcmax) and photosynthetic electron transport (Jmax), but the effect on Jmax was statistically significant only at the two highest nitrogen supply levels. The results indicate that yellow birch may increase photosynthetic capacity, biomass, and growth in the future when [CO2] is higher.
基金The research was funded by a NCASI grant to S.T. Gower. Wang CK was supported by Innovated Talent Program of Northeast Forestry University (2004-07)
文摘Safe and economical disposal of paper mill sludge is a key consideration for forest products industry. A study was conducted to examine the effects of amendments of sludge and nutrients on soil surface CO2 flux （Rs） in northern hardwood forests and to quantify the relationship among Rs, soil temperature, and moisture in these stands. The experiment was a randomized complete block design that included sludge-amended, fertilized, and control treatments in sugar maple （Acer saccharum Marsh） dominated hardwood forests in the Upper Peninsula of Michigan, USA. Results showed that Rs was positively correlated to soil temperature （R^2 = 0.80, p 〈 0.001）, but was poorly correlated to soil moisture. Soil moisture positively affected the Rs only in the sludge-amended treatment. The Rs was significantly greater in the sludge-amended treatment than in the fertilized （p = 0.033） and the control （p = 0.048） treatments. The maximum Rs in the sludge-amended treatment was 8.8 μmol CO2 · m^ 2. s^-1, 91% and 126% greater than those in the fertilized （4.6 μmol CO2 · m^-2· s^-1） and control （3.9 μmol CO2· m^- 2· s^-1） treatments, respectively. The Rs did not differ significantly between the fertilized and control treatments. The difference in Rs between sludge-amended and the other treatments decreased with time following treatment.
基金This research was supported by National Natural Science Foundation of China (Grant No. 40171092).
文摘The forest ecosystem plays an important role in the global carbon cycling. A study was conducted to evaluate soil CO2 flux and its seasonal and diurnal variation with the air and soil temperatures by using static closed chamber technique in a typical broad-leaved/Korean pine mixed forest area on the northern slope of Changbai Mountain, Jilin Province, China. The experiment was carried out through the day and night in the growing season (from June to September) in situ and sample gas was analyzed by a gas chromatograph. Results showed that the forest floor was a large net source of carbon, and soil CO2 fluxes had an obvi-ous law of seasonal and diel variation. The soil CO2 flux of broad-leaved/Korean pine mixed forest was in the range of 0.302.42 mmol穖-2穝-1 with the mean value of 0.98 mmol穖-2穝-1. An examination on the seasonal pattern of soil CO2 emission suggested that the variability in soil CO2 flux could be correlated with variations in soil temperature, and the maximum of mean CO2 flux occurred in July ((1.27±23%) mmol穖-2穝-1) and the minimum was in September ((0.50±28%) mmol穖-2穝-1). The fluctuations in diel soil CO2 flux were also correlated with changes in soil temperature; however, there existed a factor for a time lag. Soil CO2 flux from the forest floor was strongly related to soil temperature and had the highest correlation with temperature at 6-cm depth of soil. Q10 values based on air temperature and soil temperature of different soil depths were at the ranges of 2.09–3.40.
基金This is a key project of National Natural Science Foundation of China.
文摘Middle-sized chambers (40cmx40cmx20 cm) and an infrared gas analyzer (IRGA) were used for the measurement of net photosynthesis of the grass layer and soil CO2 evolution, in Quercus liaotungensis Koidz. forest, which is a typical temperate forest ecosystem in the mountainous areas of Beijing. Changes of CO2 concentrations in both the atmosphere (2m above canopy) and the forest canopy (2m below the top of the canopy) together with those of net photosynthesis and soil CO2 evolution were also examined, in order to find the characteristics of CO2 exchange between the different components of the temperate forest ecosystem and the atmosphere. Atmospheric CO2 averaged (323+10) and (330+1) mol mol-1 respectively in summer and autumn. During the 24-hour measurements, large differences as much as -46 and -61 mol mol-1 respectively in the atmosphere and forest were found. Net photosynthesis of the grass layer in summer was (2. 59 9+ 1.05) mol CO2 m-2 S-1, two times of that in autumn, (1.31+0.39) mol CO2 s-1 In summer, there was much more CO2 evolved from soil than in autumn, averaging (5.18+0.75) mol CO2 m-2 s-1 and (1.96 + 0.57) (mol CO2 m-2 s-1, respectively. A significant correlation was found between soil CO2 evolution and ground temperature, with F =-0.864 2+0.310 1X,r=0.7164, P<0.001 (n=117). Both the minimal atmospheric CO2 level and the maximum net photosynthesis occurred around 14:00; and an increase in atmospheric CO2 and of soil CO2 evolution during night times were also found to be remarkable.
文摘The temperature change and rate of CO2 change are correlated with a time lag, as reported in a previous paper. The correlation was investigated by calculating a correlation coefficient r of these changes for selected ENSO events in this study. Annual periodical increases and decreases in the CO2 concentration were considered, with a regular pattern of minimum values in August and maximum values in May each year. An increased deviation in CO2 and temperature was found in response to the occurrence of El Niño, but the increase in CO2 lagged behind the change in temperature by 5 months. This pattern was not observed for La Niña events. An increase in global CO2 emissions and a subsequent increase in global temperature proposed by IPCC were not observed, but an increase in global temperature, an increase in soil respiration, and a subsequent increase in global CO2 emissions were noticed. This natural process can be clearly detected during periods of increasing temperature specifically during El Niño events. The results cast strong doubts that anthropogenic CO2 is the cause of global warming.
文摘Changes in CO2 and temperature are correlated, but it is difficult to observe which is the cause and which is the effect. The release of CO2 dissolved in the ocean into the atmosphere depends on the atmospheric temperature. However, examining the relationship between changes in CO2 caused by other phenomena and temperature is difficult. Studies of soil respiration (Rs) since the late 20th century have shown that CO2 emissions from soil respiration (Rs) are overwhelmingly greater than CO2 emissions from fossil fuel combustion. This is also noted in the IPCC carbon budget assessment. In this paper, the dependences of Rs on temperature, time, latitude, precipitation, seasons, etc., were investigated using the latest NASA database. The changes in temperature and Rs correlated well. There is also a good correlation between Rs and CO2 generation. Therefore, an increase in temperature results in an increase in CO2. On the other hand, there is no evidence other than model calculations that an increase in anthropogenic CO2 is mainly linked to a rise in temperature. The idea that global warming is caused by anthropogenic CO2 production is still a hypothesis. For these reasons, the relationship between global warming and anthropogenic CO2 should be reconsidered based on physical evidence without preconceptions. .
基金supported by the National Natural Science Foundation of China (No.71003092)the National Basic Research Program (973) of China (No.2010CB833504-2)
文摘As a conventional farming practice, tillage has lasted for thousands of years in Loess Plateau, China. Although recent studies show that tillage is a prominent culprit to soil carbon loss in croplands, few studies have investigated the influences of tillage on the responses of soil CO2 efflux （SCE） to soil temperature and moisture. Using a multi-channel automated CO2 efflux chamber system, we measured SCE in situ continuously before and after the conventional tillage in a rain fed wheat field of Loess Plateau, China. The changes in soil temperature and moisture sensitivities of SCE, denoted by the Q10 value and linear regression slope respectively, were compared in the same range of soil temperature and moisture before and after the tillage. The results showed that, after the tillage, SCE increased by 1.2-2.2 times; the soil temperature sensitivity increased by 36.1%-37.5%; and the soil moisture sensitivity increased by 140%-166%. Thus, the tillage-induced increase in SCE might partially be attributed to the increases in temperature and moisture sensitivity of SCE.
文摘【目的】研究稻田生态系统中土壤钙、镁元素生物地球化学循环对长期大气CO2浓度升高的响应。【方法】利用中国稻田FACE(free air carbon-dioxide enrichment)试验平台,包括Ambient(对照,自由大气CO2浓度约为370μmol·mol-1)和FACE(比对照大气CO2浓度高200μmol·mol-1)2个试验处理,在2004、2005和2007年稻季不同生育期原位采集5cm和15cm处土壤溶液并测定其中Ca、Mg浓度。【结果】在2004、2005和2007年,FACE处理5cm处土壤溶液Ca浓度分别是对照处理的125%、106%和72%,Mg浓度分别是对照处理的115%、104%和75%;FACE处理15cm处与5cm处土壤溶液Ca浓度的比值在2004、2005和2007年分别是对照处理的71%、114%和180%,Mg的比值分别是对照的74%、104%和159%;2007年FACE处理0-15cm耕层土壤溶液Ca、Mg浓度分别比对照处理低6.8%和4.6%。【结论】连续大气CO2浓度升高可改变土壤溶液中Ca、Mg元素在不同深度耕层的分布,提高15cm处与5cm处土壤溶液Ca、Mg浓度的比值,且这种影响存在一定的累积效应。稻田生态系统Ca、Mg循环对长期大气CO2浓度升高的响应值得深入研究。
