CTENOMYS MENDOCINUS, A KEYSTONE SPECIES AND AN ECOSYSTEM ENGINEER AT THE SOUTH OF THE PUNA

BORGHI, CARLOS EDUARDO; BORRUEL, NATALIA; ANDINO, NATALIA; CANOVAS, GABRIELA; SRUR, ANA; CAPPA, FLAVIO

Mendoza

Simposio; 10th Intenational Mammalogical Congress; 2009

Keystone species are those species whose impact on its community or ecosystem is disproportionately large in relation to its abundance. Ecosystem engineer species are those who modulate directly or indirectly the availability of resources to other species, by causing physical state changes in biotic or abiotic materials. Many works have suggested that others subterranean rodents could be considered as subterranean ecosystem engineers.  With respect to the effect of Ctenomys at the Desertic Puna, it can be observed even at the landscape level.  Within this framework, we studied the role of Ctenomys in the functioning of the Desertic Puna ecosystem, at the Reserva Don Carmelo, San Juan, Argentina.  We found that Ctenomys activities modified soil, vegetation structure, plant survival, floration, fructification, seed production and seedling emergence. It also modified the thermal landscape by its activity on the substrate. As a combination of their effect as keystone species and an ecosystem engineer, their indirect effects modify plant composition, plant cover, species distribution and their abundance (i.e. increasing relative abundances of Liolaemus ruibali), habitat use of mammals (like guanacos) or birds (as Oreopholus ruficollis, Muscisaxicola alpina and Geositta cunicularia).  The activity of Ctenomys switches fom a community structured by bottom up process (growth limiting resources like water and temperature) toward a community structured by top down process (by herbivory of Ctenomys population). Then, Puna populations can be under a dual control by resources and subterranean herbivores in a cycle of approximately 5 years long.