Because of the development of tourist activities and the facilities in the show cave, the closed system of show cave has been changed into the complicated open system. The great number of the visitors and the landscap...Because of the development of tourist activities and the facilities in the show cave, the closed system of show cave has been changed into the complicated open system. The great number of the visitors and the landscape lights give great deal of thermoenergy to the show cave system, especially the high intensive lights make the temperature nearby goes up very fast and reduce the humidity. After the visitors leaving and the lights switching off, the temperature goes down and humidity increases even upto saturation, the condensation taken place. In the dry seasons, the cave humidity is relative low, even down to 40 50 percent. The administrations of show cave rushes the water to clean the touristic trails and keep the high humidity as to protect the cave environment. Under the function of artificial readjustment, the humidity of Yaolin cave atmosphere reaches to 97-100 percent throughtout the year.展开更多
To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement ...To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO 2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO 2 exchange （NEE） was （-71.6±5.7） and （-65.3±5.3） g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink （117.4-126.2 g C m-2 yr-1）. However, after considering the harvested grain, the agro- ecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration （R eco ） were sensitive to changes in soil water content （SWC）. When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation （PAR）, and a highly significant relationship between R eco and soil temperature （T s ）. However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the R eco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily R eco , whereas the R eco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated R eco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.展开更多
文摘Because of the development of tourist activities and the facilities in the show cave, the closed system of show cave has been changed into the complicated open system. The great number of the visitors and the landscape lights give great deal of thermoenergy to the show cave system, especially the high intensive lights make the temperature nearby goes up very fast and reduce the humidity. After the visitors leaving and the lights switching off, the temperature goes down and humidity increases even upto saturation, the condensation taken place. In the dry seasons, the cave humidity is relative low, even down to 40 50 percent. The administrations of show cave rushes the water to clean the touristic trails and keep the high humidity as to protect the cave environment. Under the function of artificial readjustment, the humidity of Yaolin cave atmosphere reaches to 97-100 percent throughtout the year.
基金supported by the National Natural Science Foundation of China (31171506 and 31071375)
文摘To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO 2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO 2 exchange （NEE） was （-71.6±5.7） and （-65.3±5.3） g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink （117.4-126.2 g C m-2 yr-1）. However, after considering the harvested grain, the agro- ecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration （R eco ） were sensitive to changes in soil water content （SWC）. When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation （PAR）, and a highly significant relationship between R eco and soil temperature （T s ）. However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the R eco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily R eco , whereas the R eco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated R eco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.
