关键词: 氮沉降, 陆地生态系统, 土壤酶活性, 氮磷添加

Abstract: In order to improve the accuracy of photosynthetic light-response curve model in data fitting and explore the photosynthetic-physiological characteristics of plants from different provenances under changing habitat conditions, photosynthetic characteristics of Quercus variabilis from six provenances were studied. The research materials were twoyear-old seedlings of Q. variabilis from six provenances, i.e., Zhuanghe of Liaoning Province (LNZH), Pinggu of Beijing (BJPG), Huanglong of Shannxi Province (SXHL), Jiyuan of Henan Province (HNJY), Hefeng of Hubei Province (HBHF), and Anning of Yunnan Province (YNAN). Five photosynthetic lightresponse curve models were chosen, i.e., rectangular hyperbolic model (RHM), non-rectangular hyperbolic model (NHM), exponential model (EM), modified rectangular hyperbolic model (MRHM), and subsection function model (SFM). These models were adopted to fit the photosynthetic light-response curve data of six Q. variabilis provenances. The photosynthetic parameters were compared among the five models and the photosynthetic characteristics of the six provenances were analyzed. The results showed that: (1) among the five models, MRHM and SFM had better fitting results in terms of conformity with measured values; (2) different models obviously affected the initial quantum efficiency (α), maximum net photosynthetic rate (P_nmax) and dark respiration rate (R_d). For example, P_nmax and R_d fitted by EM and SFM were significantly lower than those derived from the other models (P<0.05), and P_nmax fitted by RHM and NHM were significantly higher than those obtained by the other models. Besides, the significance of photoresponsive parameters among different provenances varied with the selected models; (3) there were significant differences of P_nmax and R_d among provenances (P<0.05). For instance, P_nmax of SXHL provenance was significantly higher than those of the other provenances (P<0.05), while R_d of HNJY provenance was significantly higher than those of the other provenances (P<0.05); and (4) the warm temperate provenances except LNZH would adapted better to the tested habitat.

Key words: nitrogen and phosphorus addition, terrestrial ecosystem., soil enzyme activity, nitrogen deposition