Seed and cone diversity and seed germination of Pinus pinea in Strofylia Site of the Natura 2000 Network

Variation in cone size, seed number per cone, seed potential, seed efficiency, seed morphology and seed germination behavior of Pinus pinea and its relation to stand conditions was analyzed. Data were collected from P. pinea forest in Strofylia, southern Greece, a forest that belongs to the Natura 2000 European network and the RAMSAR convention and is characterized by the absence of regeneration for many decades. The pine stands found in the area were distinguished into five categories according to a previous study and our observations, regarding stand age, canopy cover and the degree of stress by human pressure. The categories are: (I) young artificial, (II) closed-mature, (III) open-mature, (IV) over-mature stands and (V) highly degraded stands. Cones were collected from all stand types and their morphological characteristics as well as their seed production were measured. Seeds were extracted from the collected cones, measured and their germination behavior was tested. The findings showed that the over-mature and the high degraded stands and to a lesser extent, the closed-mature stands, produced significantly smaller cones with a lower seed potential, a lower number of filled seeds per cone, a greater number of not fully developed seeds and reduced seed morphological characteristics than the young and open-mature stands. However, the seed germination behavior of fully developed seeds was only slightly affected by the stand type.