关键词: 补播, 功能群特征, 物种组成, 休牧, 典型草原, 自由放牧

Abstract: Potential pollen source is an important parameter in the maize pollen dispersal model. In order to determine the strength of maize potential pollen source, the daily pollen emission and hourly flowering rate were measured. The product was calculated to estimate the hourly pollen emission as the model input of the potential pollen source. On basis of the data obtained from Lishui experiment in 2009, the normal distribution function was used to simulate the diurnal pattern of hourly pollen emission and then air temperature and relative humidity were introduced to modify this model. Firstly, the data obtained from Gongzhuling and Lishui experiments in 2010 were used to validate the normal model. The measured hourly pollen emissions of “Zinuo18” and “Jidan35” in Gongzhuling experiment and “Zinuo18” and “Su608” in Lishui experiment were compared with the simulated values. Results showed that the root mean squared errors (RMSE) between the measured and simulated values of the four maize varieties were 2.24×10⁵, 1.52×10⁵, 1.24×10⁵ and 8.92×10⁴ grain·plant^-1, and the determination coefficients (R²) were 0.330, 0.545, 0.365 and 0.606. Then the same data were used to validate the model modified by air temperature and relative humidity. Results showed that RMSE between the measured and simulated values of the four maize varieties decreased to 1.25×10⁵, 9.03×10⁴, 5.14×10⁴, and 4.22×10⁴ grain·plant^-1, and R² values increased to 0.656, 0.718, 0.779 and 0.843. Model was obviously improved, which could greatly increase the accuracy of the maize pollen dispersal model.

Key words: typical steppe, species composition, non-grazing, reseeding, free-grazing, functional group characteristics