An international network to monitor the structure, composition and dynamics of Amazonian forests (RAINFOR)

The Amazon basin is likely to be increasingly affected by environmental changes: higher temperatures, changes in precipitation, CO2 fertilization and habitat fragmentation. To examine the important ecological and biogeochemical consequences of these changes, we are developing an international network, RAINFOR, which aims to monitor forest biomass and dynamics across Amazonia in a co-ordinated fashion in order to understand their relationship to soil and climate. The network will focus on sample plots established by independent researchers, some providing data extending back several decades. We will also conduct rapid transect studies of poorly monitored regions. Field expeditions analysed local soil and plant properties in the first phase (2001–2002). Initial results suggest that the network has the potential to reveal much information on the continental-scale relations between forest and environment. The network will also serve as a forum for discussion between researchers, with the aim of standardising sampling techniques and methodologies that will enable Amazonian forests to be monitored in a coherent manner in the coming decades

The primary gene pool of cassava (Manihot esculenta Crantz).

A crop gene pool comprises three distinct categories of gene suppliers, primary, secondary, and tertiary gene pools. The primary gene pool (GP-1) is composed of gene reservoirs that cross easily with the domesticate and the crosses produce fertile offspring regularly. The secondary (GP-2) and tertiary (GP-3) gene pools comprise gene sources that cross with variable degrees of diffilculty with the crop species, this implies less close genetic distances. The GP-1 is further subdivided in cultivated and wild gene pools. The cultivated gene pool englobes commercial stocks of the crop besides indigenous landraces and folk varieties of the domesticate. The wild GP-1 of a crop comprises putative ancestors and closely related species that show a fair degree of fertile relationships with the domesticate. Two Douth American wild subspecies of cassava (M. flabellifolia and M. peruviana) are natural members of the wild GP-1 of the species. Another Brazilian species (M. pruinosa) is so close morphologically to the two wild subspecies of cassava that it may turn out another member of the wild GP-1 of the indigen. The GP-2 of cassava is more difficult to delimit as few species have been tested for genetic compatibility. Biosystematic crosses carried out between the crop and a number of wild species suggest a dozen of them as components of the GP-2, the majority are Brazilian species

Caracterização florística, fitossociológica e regeneração natural do sub-bosque da reserva genética florestal Tamanduá, DF.

O presente trabalho, desenvolvido na Reserva Genética Florestal Tamanduá, DF, teve como objetivo efetuar o levantamento fitossociológico, composição florística e distribuição espacial do indivíduos das espécies arbóreas ocorrentes no sub-bosque da Reserva, focalizando Cariniana estrellensis (Raddi) O. Kuntze, Apuleia leioscarpa (Vogel) J. F. Macbr.; Copaifera langsdorffi Desf., Anadenanthera macrocarpa (Benth) Brenan, Virola sebifera Aubl., Hymenaea courbaril var. stilbocarpa (Hayne) Lee & Lang., Aspidosperma discolor A. St. Hil., Astronium fraxinifolium Schott e Schefflera morotoni B. Maguire, Stey. & Frodin, consideradas prioritárias para conservação in situ. Foram utilizados cinco transectos com 10 m de largura cada, alocados equidistantes e de comprimento variável, demarcados perpendicularmente ao curso da drenagem principal. Foram encontrados 21.482 regenerantes ha (elevado a -1) em 69 espécies, 53 gêneros e 39 famílias botânicas. Em número de espécies, as famílias que mais se destacaram entre os regenerantes foram, em ordem decrescente, Leguminosae, Rubiaceae, Sapindaceae e Meliaceae. Entre os jovens, as famílias com maiores valor de importância (VI) foram pela ordem Meliaceae (32,78%), Rubiaceae (13,92%), Burceraceae (13,76%), Rutaceae (8,54% e Hippocrateceae (6,36%), totalizando 75,36% de valor de importância e 78,56% de valor de cobertura. Todas as espécies objeto deste trabalho ocorreram entre os regenerantes, destacando-se Cariniana estrellensis, porém apenas Copaifera langsdorffi e Virola sebifera ocorreram entre os indivíduos jovens. O quociente de mistura de 1:3 indicou tratar-se de uma mata rica em espécies, comparativamente a outros tipos florestais. A distribuição espacial dos regenerantes das espécies em questão mostrou padrões diferenciados