‘Campos de murundus’ are a typical landscape of Central Brazil characterized by countless rounded earthmounds (the ‘murundus’), which are covered by woody ‘cerrado’ (savanna) vegetation and are found scattered over a grass-covered surface (the ‘campo’). A detailed study was carried out in the region of Cuiabá, state of Mato Grosso on a particular campo de murundus (area of 5.065 ha) lying in a sedimentary depression where the earthmounds are true islands during the annual floods, allowing the colonization both by cerrado plants and by termites. The mounds were mapped and measured for their size and shape. Mounds' diameters ranged from 0.2 to 22.0 m and heights ranged from 0.1 to 1.1m. The 445 smaller mounds (< 0.8 m diameter) were found to have a clumped distribution, occupying 0.1% of the area. They are actually small termite nests built by Armitermes euamignathus. The 80 larger mounds (> 0.8 m diameter) were uniformly distributed, occupying 6.3%, of the area. These mounds are colonized by Cornitermes snyderi and Cornitermes bequaerti which build big termite nests on the summit of the mounds. Soil analyses indicated a close similarity between the campo and the surrounding cerrado whose soils had coarser texture and were poor in nutrients. Soils of the earthmounds and termite nests showed finer texture, lower pH and higher amounts of mineral nutrients. It is suggested here that this particular type of campo de murundus is formed mainly from the localized activity of nest-building by termites, followed by nest degradation, during many generations of termite colonies.

Campos de murundus (earthmound fields) are common throughout the cerrado (savanna) in Brazil. They have a clearly defined distribution particularly where they are associated with ground water. There is a distinctive woody vegetation on the discrete mounds contrasting with surrounding grass-covered depressions.

After a reconnaissance ground and air-photograph survey of the nature and distribution of mounds within the Federal District, four one-hectare plots were chosen for detailed study within the ecological reserve of the University of Brasília. Measurements were made of the size, shape and frequency of mounds. Numbers varied from 26 to 61 ha-1 with a uniform distribution occupying 10–50% of the plots. Heights ranged from 0.05 to over 2 m. The generally semi-elliptical shape in ground plan had an average size of 7 by 5.5 m with no evidence of preferred orientation although water scouring from runoff partly influences the morphology. Volumes varied from 0.01 m3 to 141.5 m3. The soils of the murundus differed from those of surrounding depressions by being better drained, with bright colours and strong cohesive structures; they were more argillic with lower base saturation and pH values. Such sites favour colonization both by cerrado plants and by termites. A classification of the murundus is postulated. Although this paper does not consider the origins of murundus, they appear to relate more closely to drainage and differential erosion than to termite activity.