Observations on the Vegetation of Northeastern Mato Grosso: I. The Woody Vegetation Types of the Xavantina-Cachimbo Expedition Area

摘要: The Xavantina-Cachimbo Expedition worked during 1967-9 in a 20 km square around base camp (12 $^\circ$ 49' N, 51 46' W), ca. 260 north of Xavantina (NE Mato Grosso) and near itself. vegetation is special interest because the situated junction savanna region Central Brazil Amazonian forest. It pattern (cerrado), woodland (cerradao), forest treeless grassland (campo) with often remarkably abrupt boundaries between different communities. Until 1967 area had been very little affected by man. climate characterized high temperature throughout year, an annual rainfall about 1200 to 1400 mm, more or less rainless dry season from June September inclusive. During cerrado, campo some forms cerradao are subject fire, but not burned every year. forest, except Deciduous Seasonal normally burned. rocks consist sandstones overlying shale mudstones. sandstone weathers form widespread dystrophic soils low nutrient content, whilst finer textured rocks, exposed deeper valleys, produce somewhat richer mesotrophic soils. woody types classified into three Evergreen ('Swampy Gallery' 'Valley' 'Dry' forest), cerrado. Swampy Gallery found along streams where water table close surface even bordered on one both sides strips campo. In composition it resembles impoverished rain top-storey dominated Qualea ingens Q. wittrockii, growing sometimes 40 m, undergrowth includes numerous dicotyledons, Scitamineae, grasses other monocotyledons. At slightly higher level stream valleys there another type tall Valley which characteristic trees (all m) Apuleia molaris, Copaifera langsdorfii, Hymenaea stilbocarpa Ormosia sp. (Tento). Much most extensive Dry represents southern fringe covers vast stretching away northwards area. This mixed community seldom grow than m. abundant species upper storey studied Chaetocarpus echinocarpus, Licania blackii, L. kunthiana, Sacoglottis guianensis Xylopia amazonica. transition cerrado abrupt, elsewhere ecotone Hirtella glandulosa recognizable nodum, occupying zone up 4 wide. Characteristic this Emmotum nitens, Sclerolobium paniculatum Vochysia haenkeana, as well H. glandulosa. boundary appears be dynamic indications that has recently invaded present does seem primarily dependent burning shows relation soil conditions, though apart clay content latter much alike. Cerrado lower degree crown cover cerradao; open grassy extremely variable floristic no clearly defined associations could recognized. sharp determined height wet season. occupied only top becomes leafless include Cedrela fissilis, Piptadenia macrocarpa, Platypodium elegans Sterculia striata, Acacia polyphylla Bauhinia cupulata second storey. Bamboos palm Acrocomia features under-growth. Floristically similar calcareous Goias Minas Gerais. fringed cerradao, termed Magonia pubescens/Callisthene fasciculata cerradao.