Seed Dispersal and Germination of 2 Native Tree Species: Gmelina arborea (Roxb.) and Terminalia chebula Retz. var. chebula.

ABSTRACT: Forest restoration, using native forest trees (the so called “framework tree species”), requires detailed knowledge of the dispersal ecology of such trees. This project was conducted in Doi Suthep-Pui National Park, Chiang Mai Province. The first part was to determine seed attractiveness to wildlife of Gmelina arborea Roxb. and Terminalia chebula Retz. Var. chebula and their seed-dispersal mechanisms, by direct observation with binoculars in the natural habitat. Attractiveness to seed-dispersing wildlife is an essential characteristic of framework species, which accelerates biodiversity recovery. Two squirrel species, Callosciurus finlaysoni and Tamiops mcclellandi dispersed seeds of both trees species, whilst Callosciurus erythaeus was an additional disperser of T. chebula. 

The second part of the project investigated optimal pre-sowing seed treatments, to maximize germination of Terminalia chebula seeds. The four different pre-sowing treatments tested were i) kept at ambient temperature in water for 2 days, ii) seeds dipped in 0.01 M sulfuric acid for 10 seconds, iii) heated in water to 70 º C and iv) seeds scarified by cutting a small wound in the testa. Percent germination, resulting from dipping in sulfuric acid and soaking in hot water, was lower than the control. Percent germination with scarification by hand and soaking in hot water for two days did not differ significantly from the control group. However, median length of dormancy (MLD) of scarified seeds was significantly reduced.