Predicting forest management effects on the oak-rodent mutualism

TERESA MORÁN LÓPEZ; THORSTEN WIEGAND; JUAN MANUEL MORALES; FERNANDO VALLADARES ROS; MARIO DÍAZ ESTEBAN

Coimbra

Congreso; IV Congreso Ibérico de Ecología. La Ecología y los retos sociales; 2015

AEET Y SPECO

Acorn dispersal in highly managed holm-oak woodlands depends on wood mice(Apodemus sylvaticus) activity. However, mice can act as either net seed predators ormoderately efficient acorn dispersers depending on environmental conditions. Wedeveloped an agent-based model (ABM) that simulates acorn dispersal by mice in aanthropogenic habitats. In our model two cascade processes occur: (1) forestmanagement modifies intraspecific competition for acorns and shelter availability, and(2) mouse adapt their foraging decisions to these new environmental conditions. Ourmodel assumes that the main motivation of mice to mobilize and cache acorns is tostore them for winter consumption. Therefore, mice carry seeds away from potentialcompetitors taking an acceptable amount of predation risks during mobilization andcaching them in areas where pilfering risks are low. Our model was calibrated with fielddata and validated with four independent landscapes that included forest interiors withcontrasting stem densities, forest edges, small forest fragments, and savanna-likewoodlands (dehesa). The model predicted acorn dispersal patterns with only a fewempirical variables (habitat availability, stem density and shrub cover). Sensitivityanalysis on landscape parameters revealed that habitat loss was a key factor on acorndispersal quality. Shrub encroachment could buffer the negative effects of habitat losson maximum dispersal distances. Finally, we simulated shrub encroachment effects onseed dispersal quality in a dehesa. Our model predicted that a 65% of shrub cover isneeded in order to recover relatively high dispersal quality