Observations On the Vegetation of Northeastern Mato Grosso, Brazil. IV. super(1) An Analysis of the Cerrado-Amazonian Forest Ecotone

• Published in: Edinburgh journal of botany Vol. 63; no. 2; pp. 323 - 341
• Main Authors: Marimon, B S, Lima, Ede s, Duarte, T G, Chieregatto, L C, Ratter, JA
• Format: Journal Article
• Language: English
• Published: 01.11.2006
• Subjects: Roncador
• ISSN: 0960-4286; 1474-0036
• DOI: 10.1017/S0960428606000576

A study was made of the transition between the cerrado and Amazonian forest biomes on the Serra do Roncador in the northeast of Mato Grosso State, Brazil. The transition was sampled by recording the species and circumference at breast height (cbh) of all woody species [greater-than-or-equal] 15 cm cbh on five 20 x 10 m plots in each of the following four communities: ecotonal vegetation (Cerradao areas 1 and 2), and forest (Forest areas 1 and 2); while in the Cerrado sensu stricto a more rapid method had to be used because of time constraints. A total of 138 species was recorded and the results were analysed using Soerensen and Morisita Indices, TWINSPAN and DCA. In addition, comparisons were made with data from studies undertaken in 1968 in the same area by the Xavantina-Cachimbo Expedition. No species was common to all communities sampled but a seral succession of important species occurs along the transition. The Soerensen and Morisita Indices demonstrate this, with the Cerrado s.s. And Forest 2 at the two extremes showing no species in common (zero similarity) and Cerradao 1 and 2 giving the very high figures of Soerensen 0.64 and Morisita 0.84. The ecotonal cerradao is a very characteristic Dystrophic facies cerradao with Hirtella glandulosa, Emmotum nitens, Sclerolobium paniculatum and Vochysia haenkeana as its typical indicator species. The ecotone studied in the present work represents the comparatively abrupt transition from cerrado to the peripheral form of Amazonian forest (dry forest, mata seca) on flat terrain with a uniform very dystrophic soil. Other workers have suggested that this type of transition may be restricted to the headwaters of the Xingu basin, but one of the present authors has seen similar vegetation at localities in Maranhao, Rondonia, and on the Mato Grosso-Rondonia border. Comparison of the present vegetation with the survey made in 1968 shows that in this area the advancing face of the Amazonian forest has extended about 7 km southwards into the cerrado. However, in the majority of places this process has been obscured by forest clearing for agriculture. The study draws attention to the urgent need for the establishment of conservation areas in this extremely threatened and very little studied ecotone. (Received May 25 2006)(Accepted September 7 2006)