Changes in a temperate forest ecosystem as a consequence of the massive flowering and death of the understory

MARCHESINI V. A., SALA O. E., AUSTIN A. T. AND GOLDSTEIN G. H.

Mérida, México.

Congreso; Ecology in an Era of Globalization; 2006

Ecological Society of America

ABSTRACT- Most bamboos that inhabit tropical and temperate forests of South America exhibit life cycles that end with a single reproduction event and massive death of all the population. Given that these species remain many years in vegetative state before blooming, little is known about the effects of these massive flowering in terms of ecosystem dynamics. In this study, we assessed the massive flowering of Chusquea culeou, a native bamboo of the Andean region of Argentina and Chile which experienced a massive flowering event in 2001 after 60 years of dominance in the understory. We evaluated the magnitude of the masting event and compared bamboo biomass and environmental variables (i.e. light, air temperature and soil water content) in sites with and without flowering. In these sites, we also monitored the demography of bamboo seedlings that emerged after the flowering and the growth of Nothofagus nervosa samplings, one of the dominant overstorey tree species. The massive flowering caused the death of more than 90 % of the culms of the bamboo population and produced an input of 1.95 kg of dry matter/m2. The light intensity increased between 3 and 10 times in the sites with flowered Chusquea but there were no significant changes observed in the rest of the environmental variables. Seedlings of Ch. culeou colonized sites affected and not affected by the flowering and showed variable density, between 4.8 to 400 seedlings/m2. N. nervosa samplings of the bloomed areas showed a significant increase in height, number of leaves and number of buds with respect to the samplings of non-flowered sites. These results suggest that conditions established in the forest after massive flowering could promote the growth of native species as well as stimulate processes related to the forest regeneration. This is an aspect little considered in the ecology of the temperate forests of the southern hemisphere thus far.