Some possible effects involved with acid rain on plants,soils, surface waters of three selected subtropical terrestrial ecosystems in southern China,were revealed in this paper. The content of total C in layer A range...Some possible effects involved with acid rain on plants,soils, surface waters of three selected subtropical terrestrial ecosystems in southern China,were revealed in this paper. The content of total C in layer A ranged from 2.35%(Masson pine forest in Baiyunshan) to 5.33% (monsoon evergreen broad-leaved forest in Dinghushan), with medium values of 2.75% (Mixed pine forest in Heshan), and 3.87% (Masson pine in Dinghushan). The C/N ratio was low,at around 12.0 in layer A,and declined with the soil depth. The low content of total-C and total-N,as well as the C/N ratio indicated that the organic matter was decomposed well,due to the warm and rainy subtropical climate. The base cation saturation(BS) was less than 10% in all sample layers of the three sites,except one case that the BS in layer A of the Mixed pine forest in Heshan was 12.9%, showing that the soil acidification occurred to some extent. The high values of aluminum saturation(AlS) of all the three sample sites suggested that this high content of aluminum in soils was possibly associated with the input of atmospheric S and N, most likely led to the acidification of soil and soil water. The effective cation exchange capacity(CEC E) was high in these soils relative to the organic matter content, ranged from 41.6 to 78.9 meq·kg -1 in layer A, and 22.5 to 54.6 meq·kg -1 in the layer AB/B. The pH value of the surface water was lower (4.27) in a monsoon forest catchment, which was located very close to the Qingyun temple,a site associated with joss sticks and candles burning,compared with the surface water from the sky lake(pH=6.54), situated far away from the temple, and surface waters from Heshan (pH=6.91) and Baiyunshan (pH = 7.10). The mean F m/F v ratio ranges from 0.79 to 0.83,with relative smaller variations between species (Pinus massoniana and Cunnighamia lanceolata), than among different sample sites. The Ca/Al ratio differed with sample site, species, and the needle age, with the range of 57.5 (Dinghushan) to 126.8 (Heshan) for the Cunnighamia lanceo展开更多
土壤盐结皮对土壤水文过程具有重要影响,初始盐分浓度(Initial salt concentration,ISC)的差异会对盐结皮的形成过程产生不同程度的影响,从而导致土壤蒸发的差异。但目前不同ISC下盐结皮形成过程对土壤蒸发的影响机理尚不明确。因此,通...土壤盐结皮对土壤水文过程具有重要影响,初始盐分浓度(Initial salt concentration,ISC)的差异会对盐结皮的形成过程产生不同程度的影响,从而导致土壤蒸发的差异。但目前不同ISC下盐结皮形成过程对土壤蒸发的影响机理尚不明确。因此,通过试验模拟与理论分析相结合,动态监测及分析不同ISC下砂土的盐结皮形成、蒸发、土壤表面温度动态变化过程,以期阐明不同ISC下盐结皮形成过程及其对土壤蒸发的影响机理。结果表明:ISC越高,盐结皮在土壤表面出现的时间越早,覆盖率越大,且在同样光照强度和光照时间条件下土表温度增幅越小,蒸发量也越小;对数函数能较好地拟合不同ISC与累积蒸发量之间的关系(R^(2)>0.90);随着ISC的增加,盐结皮对土壤蒸发抑制效率从24.14%(10 g·L^(-1))增大到71.99%(250 g·L^(-1))。ISC会显著影响盐结皮形成的过程,并通过影响土表温度的变化进而导致土壤蒸发出现巨大差异。展开更多
文摘Some possible effects involved with acid rain on plants,soils, surface waters of three selected subtropical terrestrial ecosystems in southern China,were revealed in this paper. The content of total C in layer A ranged from 2.35%(Masson pine forest in Baiyunshan) to 5.33% (monsoon evergreen broad-leaved forest in Dinghushan), with medium values of 2.75% (Mixed pine forest in Heshan), and 3.87% (Masson pine in Dinghushan). The C/N ratio was low,at around 12.0 in layer A,and declined with the soil depth. The low content of total-C and total-N,as well as the C/N ratio indicated that the organic matter was decomposed well,due to the warm and rainy subtropical climate. The base cation saturation(BS) was less than 10% in all sample layers of the three sites,except one case that the BS in layer A of the Mixed pine forest in Heshan was 12.9%, showing that the soil acidification occurred to some extent. The high values of aluminum saturation(AlS) of all the three sample sites suggested that this high content of aluminum in soils was possibly associated with the input of atmospheric S and N, most likely led to the acidification of soil and soil water. The effective cation exchange capacity(CEC E) was high in these soils relative to the organic matter content, ranged from 41.6 to 78.9 meq·kg -1 in layer A, and 22.5 to 54.6 meq·kg -1 in the layer AB/B. The pH value of the surface water was lower (4.27) in a monsoon forest catchment, which was located very close to the Qingyun temple,a site associated with joss sticks and candles burning,compared with the surface water from the sky lake(pH=6.54), situated far away from the temple, and surface waters from Heshan (pH=6.91) and Baiyunshan (pH = 7.10). The mean F m/F v ratio ranges from 0.79 to 0.83,with relative smaller variations between species (Pinus massoniana and Cunnighamia lanceolata), than among different sample sites. The Ca/Al ratio differed with sample site, species, and the needle age, with the range of 57.5 (Dinghushan) to 126.8 (Heshan) for the Cunnighamia lanceo
文摘土壤盐结皮对土壤水文过程具有重要影响,初始盐分浓度(Initial salt concentration,ISC)的差异会对盐结皮的形成过程产生不同程度的影响,从而导致土壤蒸发的差异。但目前不同ISC下盐结皮形成过程对土壤蒸发的影响机理尚不明确。因此,通过试验模拟与理论分析相结合,动态监测及分析不同ISC下砂土的盐结皮形成、蒸发、土壤表面温度动态变化过程,以期阐明不同ISC下盐结皮形成过程及其对土壤蒸发的影响机理。结果表明:ISC越高,盐结皮在土壤表面出现的时间越早,覆盖率越大,且在同样光照强度和光照时间条件下土表温度增幅越小,蒸发量也越小;对数函数能较好地拟合不同ISC与累积蒸发量之间的关系(R^(2)>0.90);随着ISC的增加,盐结皮对土壤蒸发抑制效率从24.14%(10 g·L^(-1))增大到71.99%(250 g·L^(-1))。ISC会显著影响盐结皮形成的过程,并通过影响土表温度的变化进而导致土壤蒸发出现巨大差异。
