Abstract:

The aim of this research was to clarify the influence on soil seed banks of the ant species Formica aquilonia， whichis widely distributed in mountain meadows. Our study measured the composition of soil seed banks for 0-10 cm and 10-20 cm soil depths at the site of F. aquilonia nests， and at various distances from the nests. The influence of the soil environment on the species distribution of seed banks was also evaluated. It was found that for any given distance from ant nests， seed number and species number in the soil seed bank at 0-10 cm depth were significantly higher than at 10-20 cm. A total of 28 species belonging to 28 genera and 12 families， with the majority being from the Poaceae， were found in the soil seed bank at the center of ant nests. At depths of 0-10 cm and 10-20 cm at the nest center， the germination numbers of Plantago depressa， Agrostis turkestanica， Bromus inermis， Dactylis glomerata and Poa pratensis in the soil were significantly higher than at other sample points （P<0.05）. Perennial herbs were the plant type found in highest numbers in the soil seed bank. Again， the number of perennial herb seeds was significantly higher （P<0.05） at the nest center than at other sample points at both soil sampling depths. There was a significant positive correlation between nest size and seed number at the nest center （P<0.01）. With increasing distance from the nest center， the Shannon-Wiener diversity index， Marglef richness index， Pielou evenness index and Simpson dominance index values of the soil seed bank all exhibited a V-shaped pattern of change at both soil depths， with the species diversity index being lowest at 100 cm from the ant nest. Redundancy analysis indicated that soil available phosphorus was the main factor affecting the distribution of the soil seed bank in this area. The data show that F. aquilonia collect seeds from the surrounding environment and transport them to their nests， and so increase the seed number found at the nest site. This activity affects the spatial distribution of the soil seed bank in the nest surrounds， and causes spatial heterogeneity of the species distribution in the soil seed bank.

Key words: Formica aquilonia, soil seed bank, species composition, soil physical and chemical properties