Modelling Spanish black pine postdispersal seed predation in Central-eastern Spain

Abstract

In this research work, we specifically address post-dispersal Spanish black pine (Pinus nigra Arn. ssp salzmannii) seed predation at two different locations, one being the most common and representative location for the species and the other located on areas at their ecological limit of distribution in Cuenca Mountain (Spain). A modelling approach was employed to analyze the effect of stand and site characteristics and climate variables on the post-dispersal predation process. Each predator group (ants, rodents and birds) was evaluated by excluding the other two with different experimental devices. Our study demonstrates that the percent of removal was related with the seed rain patterns being lower in the high seed rain year of 2006 (mean ± se 11.15 ± 3.7% of removed seeds) than in the low seed rain years of 2005 and 2007 (81.71 ± 6.0% and 87.29 ± 6.6% of removed seeds respectively). In high seed production years, birds were the most important predators and rodents were the less important predator group in both Los Palancares y Agregados and Ensanche de Las Majadas. No conclusion can be obtained in low seed production years due to the high seed removal percentage by all predator groups. Experimental site and overstory density were no significant with respect to seed predation. Modelling approach show that the seed removal percentage is influenced by seed production year (MastY) a temporal effect within the year, measured by the day variable (Day) and a climatic variable (accumulated averaged maximum air temperatures 20 days before survey date, AaMAT). Further developments include the construction of stochastic models to predict the effects of climate-related variables or microhabitat characteristics on seed losses, contributing to reduce uncertainty in post-dispersal Spanish black pine seed predation dynamics and to provide credible tools to decision-makers and forest managers.Key words: mast year; post-dispersal seed predation; Pinus nigra; Mediterranean region. Resumen Modelización de predación post-dispersión de semillas de pino laricio en el Centro-este de EspañaEl presente trabajo de investigación se centra en la predación post-dispersión acontecida en dos áreas forestales, una localizada en la zona de distribución característica del pino laricio (Pinus nigra Arn ssp salzmannii) y otra en su límite ecológico de distribución dentro de la Serranía de Cuenca (España). El efecto que sobre la predación post-dispersión tienen la densidad arbórea, diferentes variables climáticas y varias características de cada masa forestal fue evaluado mediante la creación de diferentes modelos. Cada grupo de predadores (hormigas, ratones y pájaros) fue analizado por exclusión de los otros dos mediante diferentes dispositivos experimentales. Nuestro estudio demuestra que el porcentaje de semilla predada estuvo relacionado con la lluvia de semillas, siendo menor en 2006, año de abundante producción (media ± estandar error: 11.15 ± 3.7% de semillas predadas) que en 2005 y 2007, años de escasa producción de semilla (81.71 ...

Post-dispersal predation of Pinus pinaster Aiton seeds: key factors and effects on belowground seed bank

“…Our results showed that predation reduced the Pinus pinaster below-ground seed bank, corroborating what had previously been reported for other Pine species in the Mediterranean basin (Castro et al 1999;Ordóñez and Retana 2004;Zong et al 2010;Lucas-Borja et al 2010). Predation was low during the seed rain period, when temperatures were higher, and increased during autumn, as Manso et al (2014) observed for Pinus pinea in the same study area (Northern Castilian plateau).…”

“…Hulme (1997) found that rodents avoided open areas whereas ants preferred them. Lucas-Borja et al (2010) did not find basal area of the stand to be significant, perhaps because only three density levels were considered in that study (low: 15-20 m2/ha; medium: 25-30 m2/ha; high: 35-40 m2/ha).…”

“…Seed predation has been studied for other Pinus species such as Pinus pinea L. (Manso et al 2014) or Pinus nigra Arn. (Ordóñez and Retana 2004;Lucas-Borja et al 2010) in Spain; Pinus sylvestris L. in Spain (Castro et al 1999) and Scotland (Worthy et al 2006) or Pinus cembra L. in Italy (Zong et al 2010); but there is scarce knowledge about the effects of predation on the Pinus pinaster below-ground seed bank. Seed predation is usually analysed using the same number of seeds throughout the experiment (Castro et al 1999;Walters et al 2005;Lucas-Borja et al 2010;Manso et al 2014).…”

Pinus nigra Arn. ssp. salzmannii seedling recruitment is affected by stand basal area, shrub cover and climate interactions

“…Several authors have cited a number of big problems for successful natural regeneration of Spanish black pine: irregular masting conditions, dry summers over a period of at least 3 years, excessive grazing and uncontrolled ploughing Lucas-Borja et al 2010Tíscar and Linares 2014). Moreover, forecasts suggest these pine forests will be soon one of the forest ecosystems hit hard by climate change, and their current distribution could shrink dramatically ).…”

Predicciones del crecimiento en poblaciones de pino laricio (Pinus nigra Arn. ssp. salzmannii) bajo diferentes escenarios futuros de cambio climático

“…o frondosas (Quercus ilex, Q. faginea, etc.). En los extremos (tanto inferior como superior) del gradiente altitudinal, P. nigra aparece como poblaciones relictas o aisladas que están fragmentadas en pequeñas masas (Lucas-Borja et al 2010a, 2010b. En las poblaciones de P. nigra estudiadas los suelos son calcáreos y generalmente poco profundos (Soil Survey Staff 1999), abarcando desde leptosoles rendzínicos a xerorthent típicos (LucasBorja et al 2011).…”