Ecology of seed germination of Pinus sylvestris L. at its southern, Mediterranean distribution range

Abstract

Seed germination of Pinus sylvestris L. in south eastern Spain was studied under field and growth chamber conditions to assess the effect of the most representative microhabitats of these forests. Under growth chamber conditions, germination was high (almost 95%) in the litter from all microhabitats. Germination under field conditions was highest (up to 95%) in shade-free microhabitats and therefore higher soil temperature (e.g. areas of bare soil and meadows), and lowest (down to 62%) in microhabitats with dense canopy shade and thus lower soil temperature (e.g. under the canopy of pines and under the canopy of juniper). Nevertheless, germination was high also in shaded microhabitats in a year with high rainfall during the germination period, supporting the hypothesis that germination was determined by a combination of appropriate levels of soil temperature, moisture, and light intensity. In contrast, biotic speciesspecific characteristics of the microhabitat were not relevant. Germination may thus reach high percentages in all the microhabitats of the understory during rainy years that ensure appropriate soil moisture during the germination period. However, during dry years germination will concentrate in sunny microhabitats because they reach higher soil temperature early in the season before soil desiccation. These patterns have implications for forest management and stand regeneration via direct seeding.

A silviculture-oriented spatio-temporal model for germination in Pinus pinea L. in the Spanish Northern Plateau based on a direct seeding experiment

“…Similar results were reported by Lucas-Borja et al (2011). However, Castro et al (2005) observed decreasing germination rates in dense stands of Pinus sylvestris in mountainous locations of the Iberian Peninsula. In our model selection process, a significantly positive influence of overstory competition (i.e.…”

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

“…Drought alleviation and higher water availability during 2013 allowed Spanish black pine to emerge without shrub and canopy cover protection (Castro et al 2005).…”

“…Light on the forest floor is a direct consequence of canopy structure and stand/shrub density (Catovsky and Bazzaz 2000;Balandier et al 2006b;Barbier et al 2008); a high light level may increase soil temperature and climate demand, thus decreasing accordingly soil moisture by increasing soil evaporation, as recorded in this particularly difficult conditions under the lowest tree canopy cover (Table 2). Soil temperature and humidity are likely to be the two main drivers of germination and seedling emergence under field conditions (Lee et al 2004;Castro et al 2005;Del Cerro et al 2009). There is broad evidence (Holmgren et al 1997;Del Cerro et al 2009) that soil and air temperatures are lower under tree canopy, wind velocity is reduced and air humidity is higher than in open areas, thus reducing seedling transpiration demand and soil evaporation.…”

Seed quality characteristics of <i>Pinus halepensis</i> – seed germination strategy and early seedling growth

“…K. Tsitsoni (tsitsoni@for.auth.gr), Dept of Silviculture,Faculty of Forestry and Natural Environment,Aristotle Univ. of Thessaloniki,PO Box 262,Greece. ment, the seedling (Castro et al 2005). Pinus halepensis is characterized by a high germination capacity.…”