Resource partitioning and interactions enable coexistence in a grass-shrub steppe.

CIPRIOTTI, PABLO A. Y MARTÍN R. AGUIAR

JOURNAL OF ARID ENVIRONMENTS

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 2010 vol. 74 p. 1111 - 1120

0140-1963

We revisited a growth-form removal experiment after 12 years with the aim to compare the long-term population responses of three shrub species. Specifically, we were interested to know if the resource partitioning and plant interactions act as complementary mechanisms of the shrub-grass coexistence. In 1983 different plots from grass-shrub Patagonian steppes were submitted to three treatments: control, grass-, and shrub-removal during three consecutive years. In 1997 we studied nine plots from the original experiment and recorded all shrubs to compare shrub density, population size-structure, vitality, spatial patterns and neighbourhood interferences of three native and co-dominant shrub species: Mulinum spinosum, Senecio filaginoides, and Adesmia volckmanni. After 12 years of recovery, shrubs as a growth-form group, fully re-established in plots where they were removed and attained 75 % higher density in grass removal plots than in control plots. However, long-term population responses of Mulinum, Senecio, and Adesmia to removals were distinctive. On the other hand, negative and positive interferences among shrub species and between shrubs and grasses generated a complex network. Morphological and functional differences in shrub and grass species and their interactions at population-level and long-term could be a key to achieve a better comprehension of shrub-grass coexistence from semi-arid ecosystems.