Seed Dispersal Process Of Juglans Mandshurica And Fxaxinus Mandshurica

An experiment was conducted from September 2004 to December 2005 at Maoershan Laoyeling ecological station in Heilongjiang province in order to find out dispersal process and pattern of Juglans mandshurica and Fxaxinus mandshurica, primary species in natural secondary forest of Northeast China, by measures of collecting and observing and setting up seed traps at different distance. Conclusions as follows:Fruits of J. mandshurica are large and heavy and mainly depended on gravity to fall from maternal trees and most fruits are within maternal tree's canopy after falling. The number of fruits increased first and then decreased along with the increasing distance. Fruits occupy distinct distribution patterns in different stands and periods: the maximum fruits amount appears in the distance of 2~3m in gentle slope, and at 5~6m in steep slope;number of falling fruits along with distance variety alters notable in fastigume, which increasing firstly and then decreasing with the increasing distance, but not in the falling forepart and later period. Fruits' direction is in evidence and fruit's number in upgrade is more than downgrade. J. mandshurica fruits will go on post-dispersal due to the animals' behavior of looking for food. During the post-dispersal period seed size, pericarp color and falling condition will influence the dispersal process.F mandshurica seeds which small and with seed wings, dispersed by wind, began to fall from latter September till the next spring. Seed number per area increases firstly and then decreases along with the increasing distance. But some dispersal characteristics such as dispersal range and dispersal distance quiet different from J. mandshurica. Periods of E mandshurica seed dispersal can be divided into forepart and fastigium ect according to the features of the surrounded forest and environment. Seed dispersal of maternal trees in initial period is near seed resources, most seeds are concentrated in 0~5m, the furthest attained distance is 10~ 15m. Dispersed seeds number, dispersal distance and range increased sharply during fastigume, seed number maximize at 12m and 15m inside of forest and at 25m out of forest. The furthest distance seeds attained inside of forest is 70m and at outside at least 200m. Furthermore distinct characteristics are found among varied periods. Thousand kernels per weight of the seeds collected in the next spring is 54.95g less than those counterparts of seeds collected in autumn which is 61.62g and number of wormy seeds per hundred is 13.6 more than autumn which is 8.7. The factors that influencing dispersal of F mandshurica seeds are density, height, distribution, composition of surrounding trees, topography, shape of maternal trees crown and climates factors etc.Seed dispersal is one of the processes of landscape ecology. Acknowledge of seed dispersal process and mechanism not only revealing future construction composition and dynamic about species population and community, applying parameter for landscape model, but also providing theoretical foundation for vegetation resume and environment protection.