Architectural plasticity of two bamboo species (Nehouzeua dulloa A Camus andDendrocalamus hamiltonii Nees and Arn.) in successional environments in north-east India

Abstract

Two bamboo species,Neohouzeua dulloa A Camus andDendrocalamus hamiltonii Nees and Arn. show plasticity in architecture, biomass and nutrient allocation patterns over a successional gradient of up to 60 yr for the former and 25 yr for the latter. However, optimal biomass accumulation rate was attained in a 15 yr old fallow for both species. Maximum elongation and thickness of the zero-order branch (main axis) is attained in a 15 yr old fallow forNeohouzeua dulloa and in a 25 yr old fallow forDendrocalamus hamiltonii. The lower order branches produced on the zero-order branch ofNeohouzeua dulloa are generally sylleptic whereas those ofDendrocalamus hamiltonii are proleptic. Maximum elongation and thickness for the zero-order branch, and least bud dormancy on them occurred in a 15 yr old fallow forNeohouzeua dulloa and in a 25 yr old fallow forDendrocalamus hamiltonii. Dendrocalamus hamiltonii in a 5 yr old fallow had a well developed first-order branch system with diffusely placed lower order branch clusters appearing as if borne on the first-order branch, unlike in older fallows where first-order branch production was continuous and lower order branch clusters appeared as if borne on the zero-order branch itself. In older fallows both species tend to allocate more biomass and nutrients to the below-ground rhizomatous component, as an adaptation for survival and vegetative regeneration after slash and burn disturbance. The growth and architecture of both species are generally geared to capitalize upon the high light regime of the early successional environment, but with a limited ability byNeohouzeua dulloa to tolerate shade.