The impacts of shifting cultivation on secondary forests dynamics in tropics: A synthesis of the key findings and spatio temporal distribution of research

Shifting cultivation has been attributed to causing large-scale deforestation and forest degradation in tropical forest-agriculture frontiers. This view has been embedded in many policy documents in the tropics, although, there are conflicting views within the literature as to the impacts of shifting cultivation. In part, this may be due to the complex nature of this land use making generalizations challenging. Here we provided a systematic map of research conducted on shifting cultivation in tropics. We first developed a literature search protocol using ISI Web of Science that identified 401 documents which met the search criteria. The spatial and temporal distribution of research related to shifting cultivation was mapped according to research focus. We then conducted a meta-analysis of studies (n = 73) that focused on forest dynamics following shifting cultivation. A bias in research on anthropology/human ecology was evident, with most research reported from the tropical Asia Pacific region (215 studies). Other key research foci were - soil nutrients and chemistry (72 studies), plant ecology (62 studies), agricultural production/management (57 studies), agroforestry (35 studies), geography/land-use transitions (26 studies). Our meta-analysis revealed a great variability in findings on selected forest and environmental parameters from the studies examined. Studies on ecology were mainly concentrated on plant diversity and successional development, while conservation biology related studies were focused on birds. Limited impacts of shifting cultivation on some soil essential nutrients were also apparent. Apart from the intensity of past usage site spatial attributes seems critical for the successful development of fallow landscapes to secondary forests. Further research is needed to help ascertain the environmental consequences of this traditional land-use on tropical forests. Scientists and policy makers also need to be cautious when making generalizations about the impacts of shifting cultivation and to the both the social and environmental context in which shifting cultivation is being undertaken.