Effect of burnt wood removal on the natural regeneration of Pinus halepensis after fire in a pine forest in Tus valley (SE Spain)

To determine the effect of burnt tree removal on post-fire natural regenera tion of Pinus halepensis, two 2500 m(2) areas were selected six months afte r the fire in a totally destroyed mature (>70 years) pine forest. In one ar ea, all the trees were cut down and removed 10 months after the fire and, i n the other, all the trees were left standing (control). In each area, 20 p ermanent plots of 20 m(2) each were randomly placed, and all seedlings emer ging within them labeled by individual numbered plastic tags. Emergence, mo rtality, density and growth (height) of 6649 P. halepensis seedlings were m onitored during the: first four post-fire years. Seedling emergence was con centrated in the first post-fire autumn-winter period. No positive effect o n seedling emergence was detected as a consequence of burnt trunk dragging and subsequent turning over of soil. Wood removal produced an immediate ave rage seedling mortality of 33%, and notably increased seedling mortality du ring the subsequent summer, probably due to increased exposure of seedlings to sunlight and the possible debilitation of many individuals by mechanica l contact during burnt wood removal. A negative correlation of pine seedlin g mortality with height was detected, which increased significantly on wood removal in the third post-fire year. That is, short seedlings (<10 cm) in treated plots were the most likely to die during this period. In spite of t he detrimental effect of wood removal on sapling survival, seedling density four years after fire in the cleared area was large (3.3 seedlings/m(2)). Wood removal treatment reduced seedling growth: seedling height was signifi cantly higher in the control stand, and differences in seedling height grow th rate became particularly noticeable in the fourth post-fire year. The re sults denote that traditional wood removal practices do not threaten natura l post-fire P. halepensis re-establishment if initial seedling density is l arge enough. However, further studies focused on wood removal effects on th e final tree development level and other ecological aspects are necessary t o choose adequate postfire forest management. (C) 1999 Elsevier Science B.V . All rights reserved.