Document: ELO-3-30-38

Physiological plasticity and climbing rates in Lianas differing in climbing mode and vertical distribution.

LASSO, E.*

University of Puerto Rico, San Juan 00931-3360 ¹

Abstract:
The photosynthetic and growth responses of four lianas species from a Panamenian forest grown under different light regimes in a greenhouse were studied to examine the relationship between photosynthetic plasticity, climbing mode, and canopy position preference. No differences between species in their mean plasticity index was found, but some differences depending on the parameter examined. All species increased their photosynthetic rates with increasing light levels. In sun, maximum photosynthetic rate (A_max) ranged from 10.05 to 12.18, as compared with 4.73 to 5.90 micromolm^-2s^-2 for the shade treatment. Although there were no significant differences in A_max between species, the species with the highest value are those usually dominating the uppers canopy levels (UCL). Passiflora vitifolia, a tendrilar lower canopy level species, showed the lowest compensation point in the shade, the highest respiration and the lowest saturation point in the sun, a behavioral response of a shade tolerant species. Stigmaphyllum hypargyreum, a twiner UCL species behave as a shade-intolerant, with the highest respiration and compensation point in the shade, and showing inability to start climbing when grown in the shade. Climbing rates in the shade treatment were similar, but in the sun the fastest species were the UCL ones. Despite the high plasticity shown by all species, there are some differences in their physiological properties that might explain the differences in their climbing rate, and therefore their abundance in a given canopy stratum.

Keywords: Plasticity, lianas, climbing metods

This abstract is being presented at: 10:30 AM in session:
GAS EXCHANGE