Seed Germination in Lowland Tropical Rainforest Trees: Interspecies, Canopy and Fruit Type Variations

摘要

Tropical trees exhibit wide heterogeneity in their canopy status, fruit types, seed sizes and seed-size dependent seedling growth; information on the germination and growth with relation to these parameters is of enormous use to understand species distribution and management in any forest stand. This study reports seed germination performance of 48 tropical trees native to northeast India, a global hot spot, with relation to inter-species, seed size, canopy level and fruit type variations. Main fruitavailability seasons were Sep.-Dec. and Jan.-Mar. and seed size varied significantly among the tropical trees (range 0.64 mg seed-1 to 25.47 g seed-1). Of all, 16, 30 and 2 species comprised top, mid and lower-canopy status, respectively and most of them exhibited poor regeneration in the forest. Among all studied species, 81% exhibited rapid germination, 15% intermediate and 4% showed delayed germination. Overall seed germination was recorded >70% for 21 species, 40-68% for 19 and <35% for 8 species.Vangueria spinosa recorded maximum (95%), while Linociera macrophyla and Heteropanax fragrans minimum germination. Seed viability also varied significantly among species, 28% species had viable seeds for <60 days, 47% up to 61-180 days and remaining 25%for >181 days. Overall, the mid-canopy species were noted to have shown higher seed germination and prolonged viability. Considering that, tropical forests are under threat, it is expected studies regarding seed germination will enable successful nurseryoperations and planned seedling production. Also this will enhance the establishment of seedlings in the restoration activities of degraded sites through selection of native plants.