Pine seed removal in fragments of three temperate plant communities

Abstract

Background: Foraging strategies may vary among guilds of granivores and impact the tree recruitment and biodiversity of plant communities. Hypothesis: The hypotheses were: during the night in areas with tree cover rodents will be the main seed removers, insects in open areas at night, and birds in all types of plant communities during the daytime. Mathematical model: The seed removal by birds, rodents and insects was studied in a Mexican temperate forest. In order to detect differences in seed removal of Pinus patula, P. pseudostrobus, P. teocote and P. montezumae, a GLMM model with three way interaction (type of plant community, exclusion treatment and period) was carried out for each pine seed species where random variables were the variation among sites and months. Study site and years of study: This study was carried out in a Mexican temperate forest during February 2006 and January 2007. Methods: Through exclusion treatments we evaluated the seed removal of four pine species in three plant communities with two replicates (1 ha approximately) and two periods. Results: The three-way interaction was significant for all pine species (P < 0.001) (GLMM processes). The variance was greater among sites than between months. The main seed removers for all pine seed species, were: At night insects for subalpine grassland; during the daytime birds for all plant communities, and at night the rodents in pine forest, oak-alder forest and finally in the subalpine grassland. Conclusions: The rodents were the main seeds removers in areas with tree cover during the night, the insects in open areas at night, and birds in all plant communities during the daytime. Key words: birds, daytime and nighttime removal, insects, rodents, tree cover Remoción de semillas de pinos en tres comunidades vegetales templadas ResumenAntecedentes: Las estrategias de forrajeo pueden variar entre granívoros e impactar el reclutamiento de árboles y la biodiversidad de comunidades vegetales. Hipótesis: Las hipótesis fueron que: durante la noche en áreas con cobertura arbolada los roedores serán los principales removedores de semillas, los insectos en áreas abiertas en la noche; y las aves en todos los tipos de comunidades vegetales durante el día. Modelo matemático: La remoción de semillas por aves, roedores e insectos fue estudiada en un bosque templado mexicano. Con el fin de detectar diferencias en la remoción de semillas de Pinus patula, P. pseudostrobus, P. teocote and P. montezumae, un modelo GLMM con interacción de tres vías (tipo de comunidad vegetal, tratamiento de exclusión y periodo) fue llevado a cabo para cada especie de pino, donde las variables aleatorias fueron la variación entre sitios y los meses. Sitio de estudio y año de estudio: Este estudio fue llevado a cabo en un bosque templado mexicano durante Febrero 2006 a Enero del 2007. Métodos: Mediante tratamientos de exclusión nosotros evaluamos la remoción de semillas de cuatro especies de pinos en tres comunidades vegetales con dos replicas (1 ha aproximadamente) y en dos pe...