Effect of sowing season, plant cover, and climatic variability on seedling emergence and survival in burned Austrocedrus chilensis forests

URRETAVIZCAYA M.F, DEFOSSÉ G.E., GONDA H.E.

RESTORATION ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2010

1061-2971

AbstractFire is the most important disturbance factor in Cypress(Austrocedrus chilensis) forests in Patagonia, Argentina.This ecosystem recovers poorly after fire, and direct sowingcould be a potentially useful restoration practice. To evaluatethe effect of season of sowing, post-fire plant cover(PC), and climatic variability on seedling emergence andsurvival, three direct sowing studies were established intwo burned cypress stands: Trevelin (xeric conditions) andEl Bols´on (mesic conditions). Two studies were conductedin winter (2000 and 2001) and one in spring (2001). Precipitationwas higher than the mean during the 2000–2001growing season and lower during 2001–2002. At both sites,emergence and survival were much higher for winterthanfor spring-sown seedlings. In the xeric stand, emergenceand survival of winter-sown seedlings increasedwith medium and high PC values, after the humid anddry summers, respectively. However, most spring-sownseedlings did not emerge, and those that did were shortlived.Because of the more favorable growing conditionsin the mesic stand, PC had no effect on emergence andonly favored first year survival of winter-sown seedlingsafter the dry summer. Spring-sown seedlings showed noassociation with PC in the mesic site, probably becausethe first summer was exceptionally humid. We speculatethat shading plants exert a positive effect on cypressseedling establishment, likely by reducing the stress fromhigh temperatures and low water availability. Sowing ofsmall patches under the protection of understory vegetationcould be useful in restoring burned cypress stands.