Influence of environmental conditions on germinant survival and diversity of Scots pine (Pinus sylvestris L.) in central Spain

Abstract

The aim of the study was to investigate dynamics and pattern of natural regeneration and the influence of seedbed and light on germination and initial seedling survival of Scots pine (Pinus sylvestris L.) during three growing seasons. Four 5-m 2 plots in a natural Scots pine forest in central Spain were randomly established at the beginning of the regeneration process. Germination and seedling survival were recorded in 100 regeneration sampling subplots (0.25 m 2 ) per plot, while seedbed type and the relative light intensity reaching the forest floor was characterised in 1-m 2 subplots. The spatial correlations between survival, light conditions and organic matter depth were analysed through crossvariograms. Germination and survival were highly variable both within and between plots (ranging from 0 to 89%) and affected by high summer temperatures (33-35°C) in 2003. The spatial pattern characterisation of survival by Ripley's K function showed a dominant cluster distribution. Occurrence tended to be clumped when abundance was greater than 15 seedlings, whereas for lower densities, seedlings were randomly distributed. Seedlings and herbs occupied the same sites where environmental conditions were appropriate for them to live. Spatial association occurred frequently for light and organic matter depth. Results suggested that the Scots pine seedlings in our study in central Spain preferred moderate light conditions (Global Site Factor <0.40). Thus, if this forest is to be naturally regenerated with Scots pine, the shelterwood system (whereby some mother trees are left to provide shelter for at least 5 years), along with mechanical disturbance of the seedbeds, would promote seed germination, as long as a seed source is present. However, regeneration success is affected by year-to-year conditions.

Effects of Reforestation and Site Preparation Methods on Early Growth and Survival of Scots Pine (Pinus sylvestris L.) in South-Eastern Poland

“…Our results confirm that the major factors affecting natural regeneration of pine forest stands are seed yields and favourable weather conditions during seed germination and initial seedling growth [56,57].…”

Natural regeneration in Iberian pines: A review of dynamic processes and proposals for management

“…Seedling survival is also threatened after extemporal cold springs and in highly shaded environments (Calama et al, 2015b). Mortality in P. sylvestris steadily increases during the first two years after emergence, but a notable stabilization in seedling survival is found after three years (Pardos et al, 2007).…”

“…Apart from the direct limiting effect of radiation on seed germination, high rates of light are often associated with the presence of a dense herbal layer which prevents seed germination and seedling emergence. Under moderate light levels the presence of this herb layer had a weak effect on seedling emergence, suggesting that seedlings and herbs can occupy the same sites (Pardos et al, 2007). On the contrary, an increase in the light levels led to a decrease in regeneration performance because of an increased competition for resources (Módry et al, 2004).…”

La regeneración natural del pino silvestre (Pinus sylvestris L.) en el Valle del Lozoya (Madrid): germinación y supervivencia inicial

“…Cabe destacar por último que las tasas de supervivencia observadas no están necesariamente correlacionadas con sus respectivas tasas de germinación, a diferencia de lo que ocurre en otros trabajos con la misma especie y estación similar (Pardos et al, 2007). Es decir, tal y como ocurre en el caso de las parcelas de hierba, una elevada tasa de germinación en una parcela no implica que la supervivencia también lo sea y viceversa, una germinación escasa (aunque no nula, claro está) puede ir seguida de una tasa moderada de supervivencia como es el caso de las parcelas tipo Restos del bloque NW.…”

“…Lo cual es muy razonable, teniendo en cuenta que la luz incidente sobre el suelo es consecuencia directa de la estructura de la cubierta (Catovsky y Bazzaz, 2002b) y que, a su vez, el efecto de dicha luz juega un papel trascendental en las condiciones del suelo, de gran importancia porque, en última instancia, permitirán o no la germinación, supervivencia y crecimiento de las nuevas plantas (Catovsky y Bazzaz, 2002a;Emborg, 1998;Messier y Puttonen, 1995;Montgomery y Chazdon, 2002;Pardos et al, 2007).…”