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The vegetation of the well drained soils along the Suiá─Missu road in the Serra do Roncador region of NE Mato Grosso is Evergreen Seasonal forest of Amazonian type. The area lies close to the meeting place of the Amazonian forest (the hylaea) and the cerrado (savanna) formation of Central Brazil. The structure of the forest is simple: the canopy is at about 18−23 m, and is exceeded by a few scattered emergents; no recognizable strata can be distinguished among the understorey trees and the shrub and herb layers are sparse. Table 1 lists the most important species and gives information on stratification and general distribution. Most of the species appear to have a hylaean centre of distribution but extend into other vegetation types. The forest differs from related communities which lie closer to the cerrado/forest boundary in its greater height and luxuriance, the presence of additional tall tree species, and the great reduction in abundance of a cerrado floristic element. A survey on the Xavantina─São Felix road allowed us to extend previous observations on the distance to which the cerrado tree Pterodon pubescens extends into the forest. The results obtained indicate a considerable extension of forest into cerrado during the life of an individual tree. A characteristic low forest occurs in the flood plain of the Rio Suiá─Missu while Swampy Gallery forests occur on permanently waterlogged soils around the headwaters of streams. The well drained soils of the Suiá─Missu forest are very uniform, deep latosols (oxisols) of very dystrophic nature with pH (in water) between 4.0 and 5.0 (see table 2, p. 203).

No abstract

Many of the soils developed on Recent alluvium in Romney Marsh have abundant interconnecting pores, holes, and cavities in their subsurface horizons formed by the activity of roots, ants, and earthworms. Ants are considered to be the dominant agents in forming highly developed underground systems of galleries and chambers. These features are apparently continuous over large areas and are not restricted to any particular soil, but occur on differing soils with a considerable range of pH, salinity, texture, and fluctuations of water-tables. Consequently, many of the soils have drainage and other characteristics that cannot be deduced from a consideration of texture or structure (pedality) alone. The characteristics of these macropores, as revealed by the infiltration into the soil of cast-forming materials such as plaster of Paris, are described, and their origin, distribution, and significance in relation to land use are discussed.