Environmental drivers for regeneration of Mauritia flexuosa L.f. in Colombian Amazonian swamp forest

• M. flexuosa forests cover a large area of Amazonian alluvial swamps.
• Drainage conditions, flooding levels and adult basal area influence recruitment.
• Highest seedling mortality was correlated to basal area of other adult tree species.
• High species richness is favoured by lower flood levels on well drained soils.
• Increased sedimentation rates change forest geomorphology and species composition.

Mauritia flexuosa L.f. (swamp forest palm) stands are widely distributed in the poorly drained zones of flood plains and low terraces. They provide several economic and cultural resources for local human communities and play an important ecological role in Amazonia. To identify the main factors involved in the natural regeneration dynamics of M. flexuosa, we surveyed the recruitment, mortality, and survival rates of seedlings from June 2010 to November 2012 on a 1-ha plot in a flooded forest area of Colombian Amazonia. The recorded mortality and recruitment rates of M. flexuosa were higher compared to its survival rates over time. These three parameters, included in a CCA, were positively correlated to the basal area (BA) of M. flexuosa adults. The CCA the first two axes explained 88% of data variance. While recruitment was positively related to flooding levels, mortality was positively related to basal area of species other than M. flexuosa and to the lowest organic matter percentages in the topsoil. In a PCA first two axes explained 57% of variance and showed positive correlation of both basal area and seedling abundance of M. flexuosa to soil organic matter content, and to poorly drained soils. Pore water pH and percentages of sand and clay increased with improved soil drainage conditions.