To explore short-term effects of acid rain on soil respiration in three zonal evergreen broadleaf tree sapling-soil systems, i.e. Paramecia latungensis ( PL), Cyclobalanopsis glauca (CG) and Elaeocarpus glabripetalus (EG), typical of Zhejiang Province, where acid rain pollution has been severe for a long time, showers of acid rain different in pH (2.5, 4. 0 and 5.6 separately) were simulated. Soil carbon effluxes (E) of the three sapling stands were monitored in various growing seasons. ( 1 ) When the stands were stressed by severe acid rain ( pH 2.5 ), E decreased significantly in all seasons in the PL stand; dropped in winter but rose in spring and summer in the CG stand compared to the control, and varied sharply only in winter in the EG stand. the effect of acid rain moderate in pH (4.0) was significant in the PL stand where E was lower than the control in all the two years except for in August 2007, when E was 25.3％ higher than the control; in the CG stand, E dropped well below the control in December 2006 and rose up to 1.96 μmol m-2 s -1 in August 2007; and in the EG stand, E decreased by 18.0％ only in November 2007. (2) the effect of acid rain on E was not significant in the PL and EG stands at the growing period-time scale. Although in the CG stand, E increased by 87.8％ and 11.1％ respectively, by exposure to severe acid rain and moderate acid rain, only the effect of severe acid rain was significant. (3) The leading factors affecting soil respiration were soil temperature and acid rain in the PL and CG stands; soil temperature in the EG stand; and acid rain in the CG stand, where a negative relationship of E with pH of acid rain was observed.%通过利用pH 2.5、4.0和5.6的模拟酸雨喷淋乐东拟单性木兰(Paramecia latungensis)、青冈(Cyclobalanopsis glauca)和秃瓣杜英(Elaeocarpus glabripetalus)3种浙江典型地带性阔叶植物幼苗-土壤系统(编号分别为PL、CG和EG),研究了模拟酸雨短期胁迫对土壤呼吸的影响.结果表明:(1)不同生长季,重度酸雨(pH2.5)对PL和CG植物下土壤呼吸E值影响显著,PL均低于对照(pH 5.6),CG冬季低于对照而春夏较对照高,EG仅冬季变化显著.中度酸雨(pH4.0)对PL的E值作用显著,除2007年8月较对照高25.3%外,均低于对照.CG的E值于2006年12月和2007年8月分别受中度酸雨的显著影响,12月低于对照,而8月升高至1.96 μmol m-2s-1.中度酸雨仅在2007年11月使EG的E值显著降低了18.0%.(2)在生长周期内,PL和EG的土壤呼吸对模拟酸雨无显著响应,CG虽分别升高了87.8%(重度酸雨组)和11.1%(中度酸雨组),但是仅重度酸雨作用显著.(3)影响PL及CG土壤呼吸的主要因素是土壤温度和模拟酸雨,EG以土壤温度为主因子.模拟酸雨对CG土壤呼吸的作用强于PL,CG土壤呼吸E值与酸雨pH负相关.
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