中亚热带不同森林类型对地表径流磷动态的影响

Effect of forest type on the dynamics of phosphorus along with surface runoff in subtropical forests

磷是亚热带森林生产力的主要限制因子之一,其随地表径流的输出是森林磷流失的重要途径,且可能受不同森林类型的显著调控,但缺乏必要关注.着眼于中亚热带不同类型森林的地表径流,分析米槠(Castanopsis carlesii)人工幼林、杉木(Cunninghamia lanceolata)人工幼林、米槠次生林及杉木人工成熟林对地表径流总磷浓度及输出的影响,为深入认识亚热带森林磷迁移过程及有效森林经营提供一定科学基础数据.结果显示:(1)不同森林类型的地表径流产流量大小为米槠人工幼林(1506.06±5.18 m^(3)/hm^(2))>杉木人工幼林(971.56±2.88 m^(3)/hm^(2))>米槠次生林(552.85±2.45 m^(3)/hm^(2))>杉木人工成熟林(468.83±1.81 m^(3)/hm^(2));(2)不同森林类型地表径流总磷浓度之间存在显著差异,表现为米槠次生林(0.239±0.093 mg/L)>杉木人工成熟林(0.138±0.042 mg/L)>杉木人工幼林(0.064±0.033 mg/L)>米槠人工幼林(0.057±0.040 mg/L);(3)4种类型森林地表径流磷输出量为米槠次生林(124.54±1.53 g/hm^(2))>米槠人工幼林(93.24±0.98)g/hm^(2)>杉木人工幼林(72.11±0.1.22 g/hm^(2))>杉木人工成熟林(56.49±0.49 g/hm^(2));(4)4种类型森林的地表径流量与降水之间均存在极显著(P<0.01)的相关关系.上述结果表明不同森林类型磷随地表径流的输出差异显著,阔叶林磷随地表径流的流失可能显著大于针叶林.(图3表2参34)

Phosphorus(P)is one of the limiting nutrients in subtropical forests,and its output,along with surface runoff,is a major pathway for its loss.Assessing P and surface runoff would help us to better understand its flux;however,little attention has been paid to this process.Here,to provide an in-depth understanding of P cycling in subtropical forests and help for forest management,we investigated how forest type may affect P concentration and output dynamics,along with surface runoff,focusing on different types of subtropical forests:young Castanopsis carlesii plantation,young Cunninghamia lanceolata plantation,C.carlesii secondary forest,and C.lanceolata mature forest.Results showed that:(1)the surface runoff amount among the four forest types ranged from C.carlesii young plantation(1506.06±5.18)m^(3)/hm^(2)>C.lanceolata young plantation(971.56±2.88)m^(3)/hm^(2)>C.carlesii secondary forest(552.85±2.45)m^(3)/hm^(2)>C.lanceolata mature plantation(468.83±1.81)m^(3)/hm^(2);(2)P concentration in surface runoff varied significantly among the different types of forests,C.carlesii secondary forest(0.239±0.093)mg/L>C.lanceolata mature plantation(0.138±0.042)mg/L>C.lanceolata young plantation(0.064±0.033)mg/L>C.carlesii young plantation(0.057±0.040)mg/L;(3)the output of P surface runoff among the four forest types was C.carlesii secondary forest(124.54±1.53)g/hm^(2)>C.carlesii young plantation(93.24±0.98)g/hm^(2)>C.lanceolata young plantation(72.11±0.1.22)g/hm^(2)>C.lanceolata mature plantation(56.49±0.49)g/hm^(2);and(4)a significant(P<0.01)relationship between the amount of surface runoff and rainfall was observed for all types of forests.These results suggest that forest type is a major factor regulating P output,along with surface runoff,which is likely to be higher in broadleaved than in coniferous forests.