Regional and local variation in seedling emergence

Authors: Jose L Garrido Pedro J Rey Carlos M Herrera

Publish Date: 2006/08/06

Volume: 190, Issue: 1, Pages: 109-121

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Abstract

Spatial patterns of seedling regeneration of woody Mediterranean plants are widely documented with seedlings and juveniles growing almost exclusively under shrub and tree canopy Neighbourhood habitat amelioration and consequent facilitative effects on recruitment have been extensively suggested as the major determinant of such spatial pattern for Mediterranean vegetation Much less is known on recruitment patterns of perennial herbs As herbs differ from woody plants in many relevant ecological aspects and in their life cycles we would expect particularities in their recruitment dynamics We analysed the spatial regional local and finescale variation in environment herb cover litter depth air temperature and irradiance and its relationship with seedling emergence mortality and recruitment of the perennial herb Helleborus foetidus Ranunculaceae during 2 years We conducted the study in three distant localities in southeastern Iberian Peninsula defining the regional scale Local scale was defined in terms of microhabitat type based on three categories of vegetation cover under evergreen shrubs or trees under deciduous spinyshrubs and in open interspaces Finally finescale variation was defined in terms of 1 m2 sampling plots Our results showed regional local and finescale variations in recruitment with the major source of variation changing across scales Seed input was important in determining differences in recruitment both at the largest regional and the finest scale Environment had minor importance in shaping differences in recruitment at these two scales At the local scale variation between microhabitats was mainly related to differences in seedling survival through facilitative effects alleviation of water and irradiance stresses of shrub and tree cover although such facilitative effect was not consistent in all localities or years Our study thus points to a similarity in the spatial patterns of recruitment and in the environmental factors shaping such patterns between Mediterranean woody plants and perennial herbs but much more effort is needed to assess the generality of such similarityThe authors thank Ester Orive for her generous field assistance Two anonymous reviewers helped to improve a previous version of this manuscript We also thank the Junta Rectora of Sierra de Cazorla Segura y Las Villas and Sierra Mágina Natural Parks for providing working facilities This study was supported by grants PB96–0856 from the DGES Ministerio de Educación y Cultura and BOS20001122C0301/03 from the Ministerio de Ciencia y Tecnología Spain

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