Variation in seed size and its relationship to other functional traits in a seasonally dry tropical forest

Abstract

Seed size is an important plant functional trait related to important axes of plant function like regeneration and stress (shade, drought and herbivory) tolerance. Globally seed size has been found to be related to plant height and independent of leaf economic spectrum (LES) traits making it a part of a size architecture spectrum. However global relationships of seed size with other functional traits do not always show consistency across scales and in different environments. This study tried to understand the relationships of seed size with other functional traits and if these vary with environment. A literature survey showed that the trait relationships of seed size with other functional traits varies with scale and climate, with a lot of variation in the trait relationships of seed size from the tropics. In order to understand the variation in seed size and its relationship with other functional traits, seed size and its trait relationships were quantified for the entire woody plant community in a seasonally dry tropical forest, and across habitats in the forest differing in their light and water environments. Seed size did not vary across habitats. In well-lit habitats with low soil moisture seed size was found to be related to leaf mass per area a chief leaf economic trait whereas in shade habitats with high soil moisture, seed size was related to wood density, leaf dry mass and plant height. A high value of all these traits confer shade tolerance. Hence water availability drives the trait relationships of seed size in well-lit dry environments and shade is the main driver of trait relationships of seed size in shade moist environments. In order to understand if different trait combinations are successful across different habitats, the trait space was examined across habitats, well-lit dry habitats which are heterogeneous harbored a wider trait space particularly along the leaf economic spectrum, whereas shade moist habitat had a much restricted trait space.