ISSN:
1420-9098
Keywords:
Key words: Gallery forest, Ivory Coast, savanna, termites, thermoregulation.
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary: We determined density and distribution of the mounds of the fungus-cultivating termite Macrotermes bellicosus (Smeathman) in two habitats (shrub savanna and gallery forest) of the Comoé National Park (Ivory Coast, West Africa). We measured height, basal width, and interior and exterior temperatures of mounds in both habitats, and established a new method to measure the surface area of mounds.¶ In the shrub savanna, M. bellicosus mounds reached high densities (up to 22.7 live mounds/ha), whereas in the gallery forest mounds could only be found in open stands and at comparatively low densities (up to 6.5 live mounds/ha).¶ Ambient temperature had an important influence on the architecture of the mounds. Mounds in the warmer, but thermally more fluctuating shrub savanna were more structured with many ridges and turrets than the dome-like, compact mounds in the cooler, more equable gallery forest. The surface complexity was quantified as the ratio of surface (= rsf), which is the quotient of the real surface to the minimal possible surface of an ideal cone of the same height and basal width as the measured mound. By manipulating ambient temperatures, we were able to demonstrate causal relationships between temperature and mound shape. In the gallery forest, where shade was reduced surface complexity increased on mounds.¶Despite their different architecture in the gallery forest, the M. bellicosus colonies could not completely compensate for the cooler environment and had a lower than optimal nest temperature. We speculate that this might be caused by the need for a sufficient surface for gas exchange. The gallery forest is a suboptimal habitat for M. bellicosus, because of lower than optimal nest temperatures. This might limit M. bellicosus to open stands in the gallery forest and may explain its surprisingly low abundance in this habitat.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s000400050068
