Combined effects of seed provenance, plant facilitation and restoration site on revegetation success

Plant provenance, plant facilitation and the characteristics of restoration sites are critical determinants of revegetation success. Surprisingly, however, very little is known about how these key factors interact, both with each other and to complex patterns of recruitment in target plant species. We investigated, for the first time, the potential of combining seed provenance, plant facilitation and restoration site characteristics to guide revegetation efforts. As a model system, we used the Iberian pear (Pyrus bourgaeana) and three potential nurse shrub species. To this end, we completed a comprehensive reciprocal transplant experiment in five P.bourgaeana populations within a fragmented landscape at the Donana Biosphere Reserve (SW Spain). There were marked differences among provenances for seedling emergence and growth, as well as for recruitment, but no evidence of local adaptation was found. Shrubs generally had a positive or neutral effect on P.bourgaeana seedling performance with, for example survival underneath shrubs being, on average, twice as high as in open microhabitats. Interestingly, however, the magnitude and even the sign of such plant-plant interactions changed with both sowing locality and seed provenance. For instance, shrubs enhanced seedling survival and recruitment at the end of the study in four of the five sowing localities, whereas it decreased it in the remaining locality. Also, although nurse shrubs lessened seedling size of two provenances, it did not have a significant effect on the other three.Synthesis and applications. We show how revegetation success can be maximized, not only by selecting the most appropriate plant material, taking advantage of plant facilitative interactions and selecting the right restoration site, but also by using these factors in an integrated fashion. We propose local managers efficiently undertake future revegetation campaigns by mixing seeds from several genetically adequate source populations in numbers weighted according to previously estimated provenance-specific recruitment successes. Our novel approach can help to guide revegetation of many tree and plant species living in stressful conditions, such as arid, semi-arid and high mountain habitats. Foreign Language AbstractResumen La procedencia de las plantas, las interacciones de facilitacion, y las caracteristicas de los sitios de restauracion son determinantes criticos del exito de revegetacion. Sorprendentemente, sin embargo, se sabe muy poco acerca de como estos factores claves interactuan entre si, dando lugar a patrones complejos de reclutamiento en las especies de plantas a restaurar. Investigamos por primera vez el potencial de combinar la procedencia de las semillas, la facilitacion entre plantas y las caracteristicas del sitio de restauracion para guiar los esfuerzos de revegetacion, utilizando como sistema modelo el piruetano (Pyrus bourgaeana) y tres especies de arbustos potenciales nodrizas. Para ello, llevamos a cabo un experimento de trasplante reciproco en cinco poblaciones de P.bourgaeana dentro de un paisaje fragmentado en la Reserva de la Biosfera de Donana. Encontramos marcadas diferencias entre procedencias de las semillas en emergencia y crecimiento de las plantulas, asi como en reclutamiento. No hubo evidencias de adaptacion local. Los arbustos generalmente tuvieron un efecto positivo o neutral en el exito de las plantulas de P.bourgaeana; por ejemplo, la supervivencia dentro de los arbustos fue en promedio dos veces mas alta que en los microhabitats abiertos. Curiosamente, sin embargo, la magnitud e incluso el signo de tales interacciones planta-planta cambiaron tanto con la localidad de siembra como con la procedencia de la semilla. Por ejemplo, los arbustos mejoraron la supervivencia y el reclutamiento de las plantulas al final del estudio en cuatro de las cinco localidades de siembra, mientras que la disminuyeron en la localidad restante. Ademas, mientras que los arbustos nodriza disminuyeron el tamano de las plantulas de dos procedencias, no tuvieron un efecto significativo en las otras tres.Sintesis y aplicaciones: el exito de las campanas de revegetacion se puede maximizar no solo seleccionando el material vegetal mas apropiado, aprovechando las interacciones facilitadoras entre plantas y seleccionando el sitio de restauracion mas apropiado, sino tambien utilizando estos factores de manera integrada. Proponemos a los gestores locales realizar las futuras campanas de revegetacion de manera mas eficiente mezclando semillas de varias poblaciones de origen geneticamente adecuadas y en numeros ponderados de acuerdo con los exitos de reclutamiento especificos de cada procedencia (estimados previamente). Este novedoso enfoque puede ayudar a guiar con exito la revegetacion de muchas otras especies de arboles y plantas que viven en condiciones estresantes, como los habitats aridos, semiaridos y de alta montana. We show how revegetation success can be maximized, not only by selecting the most appropriate plant material, taking advantage of plant facilitative interactions and selecting the right restoration site, but also by using these factors in an integrated fashion. We propose local managers efficiently undertake future revegetation campaigns by mixing seeds from several genetically adequate source populations in numbers weighted according to previously estimated provenance-specific recruitment successes. Our novel approach can help to guide revegetation of many tree and plant species living in stressful conditions, such as arid, semi-arid and high mountain habitats.