Population ecology of Lasius flavius F. on chalk grassland.
Lasius flavus F. is a common ant species on chalk grasslands in the
south of England. This thesis examines the effects of the management
regimes and environmental conditions of these grasslands, on the
characteristics of the ant populations.
The null hypothesis of the study was that the characteristics of L.
flavus populations are not significantly affected by variation in:
1) management procedures,
2) the physical environment,
3) the biological environment.
The ant populations, management regimes and environmental
characteristics of twenty sample areas were investigated and subjected
to intensive analysis to examine this hypothesis.
The null hypothesis was rejected. The population of ants that an
area of chalk grassland supports, depends on both the management of
that area and the environmental conditions.
In the short term (2 to 4 years) more intense management leads to
significant reductions in the sizes of the soil mounds built by the
ant colonies, and reductions in the sexual productivity and sexual
investment ratios of the colonies. In the longer term (over 10 years)
the density of mounds is also reduced.
The most important environmental characteristic of the grasslands
is the soil water regime. Drier areas support a lower density of
colonies with smaller mounds.
The numbers of root aphids (the major food source of the ant) are
reduced by increased grazing intensity. Other invertebrate groups are
also affected by the management regime and the physical environment of
the sample areas.