中亚热带杉木人工林和米槠次生林树干茎流和穿透雨磷的动态特征

磷(P)伴随树干茎流和穿透雨输入到森林,成为补充亚热带森林生态系统P流失的一个重要途径,但其在不同类型生态系统中的动态特征缺乏必要的关注。以中亚热带杉木人工林和米槠次生林为研究对象,通过测定2015年6月至2018年8月间树干茎流和穿透雨中P浓度,探讨了2个林分树干茎流和穿透雨P浓度的差异、季节变化特征及影响因素。结果表明,杉木人工林树干茎流和穿透雨P浓度变化范围分别为0.002～0.026,0.003～0.024 mg/L,米槠次生林树干茎流和穿透雨P浓度变化范围分别为0.003～0.024,0.003～0.031 mg/L,2个林分树干茎流和穿透雨P浓度均在夏季表现出显著差异。2个林分的树干茎流P浓度均为夏季高于冬季,杉木人工林穿透雨P浓度在季节上无显著差异,而米槠次生林夏秋季较高,冬春季偏低,树干茎流P浓度略微高于穿透雨。2个林分的树干茎流量在4个季节均具有显著差异,米槠次生林均高于杉木人工林,而穿透雨量在季节上无差异。杉木人工林P浓度与树干茎流量和穿透雨量均呈负相关关系,而米槠次生林P浓度与树干茎流量和穿透雨量均呈正相关关系。表明不同林分林冠结构和形态学特征的差异能显著影响亚热带森林生态系统降水中P的再分配。研究结果为深入认识森林生态系统P随水文过程的动态特征提供基础数据。

Dynamics of Phosphorus Along with Stemflow and Throughfall in Middle Subtropical Cunninghamia lanceolata Plantations and Castanopsis carlesii Secondary Forests

The input of phosphorus (P) along with stemflow and throughfall is an important supplement for P loss in subtropical forest ecosystems, but the dynamics of these processes in different type of forests remain elusive. Here, based on field monitoring experiments in middle subtropical Cunninghamia lanceolata (Lamb.) Hook. Plantations and Castanopsis carlesii (Hemsl.) Hay. Secondary forests from June 2015 to August 2018, we assessed P concentrations of stemflow and throughfall among different forest types and seasons, and the associated controlling factors. The results showed that P concentrations of stemflow and throughfall in C. lanceolata plantations varied from 0.002 to 0.026 and from 0.003 to 0.024 mg/L, respectively, and those in C. carlesii secondary forests varied from 0.003 to 0.024 and from 0.003 to 0.031 mg/L, respectively, P concentrations of stemflow and throughfall varied significantly between forest types in summer. Stemflow P concentrations were higher in summer than that in winter, regardless of forest type. Throughfall P concentrations were higher during summer and autumn in C. carlesii secondary forests, but did not differ among seasons in C. lanceolata plantations. Rainfall amount of stemflow in both forest types significantly varied among different seasons, with an average of higher stemflow but similar throughfall in C. carlesiisecondary forests compared with C. lanceolata plantations. P concentrations were negatively correlated with water amounts of both stemflow and throughfall in C. lanceolata plantations, but positive correlations were found in C. carlesii secondary forests. Our results suggested that forest type that was represented by canopy structure and phenology features was an important controlling factor affecting rainfall P distribution in subtropical forest ecosystems, which could provide useful basal data for better understanding the dynamics of P along with hydrology process in forest ecosystems.