Recover of understory vegetation in clearcut stone pine (Pinus pinea L.) plantations

The recovery of understory vegetation after clear-cutting of stone pine (Pinus pinea L.) plantations is crucial for biodiversity conservation. The development of plant cover, and the richness, diversity and composition of understory plant communities were investigated within five years from clear-cutting. After three years, plant cover ranged from 48 to 74%, and was formed by over 90% of shrubs and graminoids. Diversity decreased in cut plots and the index of similarity showed marked shifts in species composition. Richness increased and around 50 new species per plot were inventoried over three years. New species showed a high proportion of annuals with broad ecological amplitude and aliens, which changed life form and chorology spectra. Most new species had low frequency, but some were still present after five years. Extinction of resident species was low, and their frequency increased with time from clear-cutting. Most of them were perennials with sprouting ability. Common features of plant communities developing in clear-cut stone pine plantations were: (1) the linear increase of plant cover during the first three growing seasons, (2) increased species richness, (3) decreased diversity, (4) invasion by annuals, and (5) invasion by Alien and Cosmopolitan species.