Which Factors Explain Reproductive Output of Mauritia flexuosa (Arecaceae) in Forest and Savanna Habitats of Northern Amazonia?

Abstract

Premise of research. The dioecious palm Mauritia flexuosa plays a critical role in the ecology and economy of the Amazon. However, little is known about the relationship between habitat variation and the reproductive dynamics of this species. We quantified variation in fruit and seed production among three habitats in northern Brazilian Amazonia and identified the abiotic and biotic factors explaining these sources of variation. Methodology. Fruits and seeds from females in six sites (three habitats) were collected. Total fruit yield per individual, dry fruit mass, dry seed mass, and seed number per fruit were calculated for each female and habitat. Multiple linear regressions were conducted on abiotic (soil physical and chemical parameters, soil moisture, flooding levels, and photosynthetically active radiation) and biotic (height, diameter at breast height, number of leaves, and crown volume) factors to determine the relationship between these parameters and reproductive output. Pivotal results. Fruit mass, seed mass, and seed number were significantly lower in the disturbed savanna than in the undisturbed savanna ecotone and forest, although total fruit yield was highest in the disturbed savanna. Soil moisture and flooding during the wet season were the best predictors of fruit and seed output. Soil organic matter also explained variation in seed mass. The number of leaves, diameter at breast height, and height were all accurate predictors of reproductive output, but crown volume should not be used to estimate fruit yields. Conclusions. Habitat affects the reproductive dynamics of this species, which can be explained by abiotic factors such as moisture availability and biotic factors such as vegetative attributes. While two years of data are not sufficient to infer broad patterns, this study provides preliminary results about the factors that explain variation in fruit and seed formation of M. flexuosa. A long-term study relating seasonality, environmental factors, and the reproductive dynamics of M. flexuosa is warranted, with profound implications for plant reproduction and regeneration patterns.