Using a simple isotope mixing model, we evaluated the relative proportion of water vapour generated by plant transpiration and by soil evaporation at two sites in the Amazon basin. Sampling was carried out at two different soil covers (forest and pasture), in a seasonal tropical rainforest at eastern Amazon where major deforestation is the result of land‐use change, and compared to a less seasonal central Amazon forest. In both forests, vapour from transpiration was responsible for most, if not all, of the water vapour generated in the forest, while it could not be detected above the grassy pastures. Thus the canopy transpiration may be a major source of water vapour to the forest and perhaps to the atmosphere during the dry season. The results are discussed in relation to predictive models based on net radiation that usually are not able to distinguish between transpiration and evaporation.
Nota técnica – Amazônia em chamas
Nota técnica – Amazônia em chamas
O fogo é um elemento comum na paisagem rural brasileira. Usado para limpar áreas recém-desmatadas e outros tipos de terreno, como pasto, frequentemente escapa ao controle e queima o que não deveria queimar (Nepstad et al., 1999). Na Amazônia não é diferente. Sua incidência na região está diretamente relacionada à ação humana e as chamas costumam seguir o rastro do desmatamento: quanto mais derrubada, maior o número de focos de calor.