Recuperação de agroecossistemas de várzea e paleovárzea amazônica no contexto das mudanças climáticas na região do médio solimões (Amazonas, Brasil)

Abstract

Agrobiodiversity in Amazonia is the result of the use and management of plant populations by current and pre-Columbian peoples, being composed of domesticated crops to different degrees and domesticated landscapes, such as agroecosystems, managed forests and anthropic soils. Currently, the agroecosystems of traditional producers on the middle Solimões River (Amazonia) are being heavily impacted by extreme events related to climate change, such as recurrent large floods. The general objective of this thesis is to analyze the impacts and recovery of ribeirinhos agroecosystems in Amazonian floodplain ecosystems after one of the most extreme floods in the middle Solimões River (2015). Our specific objectives are: a) to assess how crop agrobiodiversity was impacted and recovered after the extreme flood (chapter 1); b) compare local adaptive landscape domestication strategies to cope with extreme and normal-year floods (chapter 2); and c) examine manioc storage strategies and the distribution of this knowledge among residents of floodplain ecosystems (chapter 3). For this, between 2017 and 2019 we carried out semi-structured interviews, free-lists, guided tours, participant observation, seasonal calendars and timelines. We analyzed the alpha and beta agrobiodiversity of ethnospecies and manioc ethnovarieties managed by ribeirinho communities before, immediately after and two years after the 2015 extreme flood, comparing the impacts and agrobiodiversity in the low várzea, high várzea and paleovárzea. We identified that local communities have detailed knowledge about normal climatic patterns and they recognize that climate unpredictability makes it difficult to effectively realize the activities necessary for their survival and food sovereignty, where their local knowledge is no longer reliable. We point out that extreme climatic events have consequences for their cropping systems and associated agrobiodiversity, varying according to the degree of exposure of different environments to extreme climatic events. We verified that low várzea agroecosystems are more affected by the extreme floods and require more time for their reconstitution, whereas even after two years of management, the agroecosystems do not present similar alpha agrobiodiversity in comparison with was observed before the extreme flood. In addition, the agrobiodiversity between ecosystems (beta agrobiodiversity), which was similar before the extreme flood, was not recovered even after two years of ribeirinho management. In the case of the agrobiodiversity of manioc ethnovarieties, greater impacts were also observed in the lower várzea immediately after the flood. During extreme climatic events, local communities intensify adaptation strategies such as avoiding stress on the root systems of fruit trees, prioritizing plants that survive to floods and cultivating in less affected landscapes. Adaptation practices tend to occur more frequently in várzeas, and two adaptation practices were specific to várzeas. In addition, residents mention four techniques for storing fresh manioc; two also mentioned in archaeological or ethnographic studies (burial and basketing) and two not previously mentioned (bagging and kanaká). In the paleovárzea, where manioc production is more important as a source of income, residents have more knowledge of manioc storage techniques; however, this knowledge also persists in areas where manioc is less important for income generation. In the coming decades, the impacts of extreme climatic events on local communities are expected to increase, especially in environments more exposed to flooding. Residents suggest documenting and sharing adaptation strategies as a way to increase their resilience.