Pollen Dispersal and Its Spatial Distribution in a Seed Orchard of Larix kaempferi (Lamb.) Carr.

Pollen dispersal and its spatial distribution in a seed orchard of Larix kaempferi in Changlinggang, Jianshi, Hubei Province has been studied for 3 years. The results show that pollen dispersal is directly affected by weather conditions, with wind speed being the main factor controlling pollen dispersal. Pollen dispersal follows a date rhythm of low-high-low during the whole pollen dispersal season with a peak date for 3-5 days, and a time rhythm of low-high-low with the peak time at 10:00-16:00 during the day. For pollen density in the air there are significant differences among dates, and among different day times during dispersing. There are no significant differences between pollen densities in space with regard to horizontal directions, 8 orientations, and different positions in the tree crown in this seed orchard, in all of these cases pollens are evenly distributed. There are significant differences for pollen densities among different vertical heights, showing a cluster distribution type. The pollination level in this seed orchard is very low and needs a supplement mass pollination (SMP).