Thursday, August 9, 2007 - 8:00 AM

OOS 38-1: Community disturbance and recovery: An application of ecological theory to restoration

Francisco Garcia-Novo, Raquel Fernandez Lo Faso, and Daniel García-Sevilla. University of Seville

Partido stream watershed (Doñana N. Park, SW Spain) presents stable vegetation with few trees and some shrubs in dense grassland. It has supported husbandry for about 7 centuries and crop rotation until y. 2002. Plant communities, after repeated disturbance, now exhibit a state of high resilience where further changes are limited.
The restoration intended to reproduce the mature scrub now existing in the Park, inducing succession processes. Plans for restoration of 1500 ha of watershed were prepared, based on a detailed survey of vegetation remnants, soil type and topography. Revegetation essays were carried out in an experimental plot since 2002.
Two interventions were combined.
i) Restoring vegetation remnants planting the woody species which have been lost.
ii) Creating new scrub patches (12 to 26 m across) mimicking the horizontal and vertical structure of mature scrub: a core area with 1-3 trees (Quercus, Olea), a nucleus of fruit producing scrubs (Prunus, Pistacia, Rhamnus, Phyllirhea) and a fringe of flower scrubs (Cistus, Thymus, Lavandula, Rosmarinus).
In March 2006, 6,000 shrubs and small trees were planted in N watershed sector. Monitoring (growth and survival in plants, bird population in restored and non restored areas), have been carried out on a monthly basis ever since. On 2007 3 fresh areas were restored with patches (11,000 scrub and trees).
Trees provide perch for birds increasing diversity and acting as dispersers of scrub (and tree) fruits, a key role for this community. Scrub seedlings find an adequate regeneration niche under scrubs and trees, where grass growth is impaired by low light intensity. Community recovery occurs as scrub plants grow and gain control of space (and light) and make it possible seedling establishment. On a later phase of succession, it is birds, foxes, rabbits and some other species which will perform as dispersers creating nuclei to new communities.