Architecture and growth strategy of two evergreen species of the Western Ghats (South India). Knema attenuata (Myristicaceae) and Vateria indica (Dipterocarpaceae)

摘要

Analysing tree architecture consists in describing the successive growth stages from the seedling to the death of plants. The description and monitoring of the different types of axes (stem, branches, twigs, etc.) and lateral productions (flowers, leaves, etc.) helps in characterising the structural growth strategies. In this paper, I describe and interpret the architectural development of two species: Vateria indica (Dipterocarpaceae), an emergent, and Knema attenuata (Myristicaceae), a lower canopy species. These two species are among the most frequent species of the low elevation moist evergreen forests of the Western Ghats in South India. They were observed in the Kadamakal Reserve Forest (Coorg District, Karnataka State). Both species conform to Massart's architectural model but exhibit different ways of building up their crown and different strategies of reiteration in response to light availability in order to maintain their growth under canopy: K. attenuata reinforces its structure from the very early stage and maintains its position of a lower canopy tree through its very regular structure until it reaches the canopy, while V. indica establishes its structure once it reaches this limit. The aim of this paper is to show how two species which belong to two different vertical strata, grow and adapt in the light-limited forest environment and to describe by which way they manage to reach the canopy and intercept light.