湿地松林下6树种光合日变化及其与环境因子的关系

以红壤区湿地松林下栽植的6树种为研究对象，监测了各树种叶片净光合速率（Pn）的日变化，同时系统分析了Pn与各环境因子间的关系。结果发现，麻栎（Quercus acutissima）、黧蒴锥（Castanopsis fissa）、木荷（Schima superba）和胡枝子（Lespedeza bicolor）的Pn日变化均呈现为先增加后降低的趋势，最大值均出现在11:00，分别为(1982±266)、(1458±179)、(1611±482)、(1492±367) μmol/（m2〖DK〗·s）；而椤木石楠（Photinia davidsoniae）和杨桐（Adinandra millettii）则呈现为双峰曲线，最大值分别为（891±181）、（1085±163）μmol/（m2〖DK〗·s）。各树种日平均Pn从大到小的顺序依次为麻栎、木荷、黧蒴锥、胡枝子、杨桐、椤木石楠。方差分析发现，麻栎、黧蒴锥、木荷的Pn显著大于椤木石楠和杨桐（p＜005）。通径分析发现，黧蒴锥、麻栎和胡枝子的Pn动态变化主要受饱和水蒸气压差（VPD）、温度（T）、相对湿度（RH）和光合有效辐射（PAR）的影响；木荷主要受VPD、T和PAR的影响，而椤木石楠和杨桐的主要受VPD、T、RH的影响，且各物种各因子均具有较大的间接通径系数。

Daily variation of photosynthesis of six tree species under Pinus elliotii forest and their relations with environmental factors

Daily variations of net photosynthesis rates(Pn) of 6 tree species in red soil under Pinus elliotii forest were determined and their relation with environmental factors were analyzed using path analysis.The daily courses of Quercus acutissima,Schima superba,Castanopsis fissa and Lespedeza bicolor showed unimodal curves,with the maximum of(19.82±2.66),(14.58±1.79),(16.11±4.82),(14.92±3.67) μmol/(m2·s) at 11:00 am,and Adinandra millettii,Photinia davidsoniae presented bimodal curves,with the maximum of(8.91±1.81),(10.85±1.63) μmol/(m2·s).The sequence of daily average of Pn was Q.acutissima >S.superba > C.fissa > L.bicolor > A.millettii > Ph.davidsoniae,and significant differences were found among Q.acutissima,S.superba,C.fissa and A.millettii,Ph.davidsoniae(p<0.05).Based on pathway analysis,Pn was mainly influenced by vapor press deficit(VPD),temperature(T),relative humidity(RH) and photosynthetic active radiation(PAR) for Q.acutissima,C.fissa and L.bicolor.While S.superba was mainly influenced by VPD,T and PAR.Whereas for A.millettii and Ph.davidsoniae.