Crown asymmetry, treefalls, and repeat disturbance of broad-leaved forest gaps

• Published in: Ecology (Durham) Vol. 72; no. 4; pp. 1464 - 1471
• Main Authors: Young, Truman P., Hubbell, Stephen P.
• Format: Journal Article
• Language: English
• Published: Washington, DC The Ecological Society of America 01.08.1991; Ecological Society of America; Brooklyn Botanic Garden, etc
• Subjects: Animal, plant and microbial ecology; ARBOLES FORESTALES; ARBRE FORESTIER; Biological and medical sciences; BORDER EFFECTS; BOSQUES; CAIDA PREMATURA DE FRUTOS; CANOPY; CHUTE DE FRUITS; COPA; COUVERT; CROWN; CUBIERTA DE COPAS; ECOLOGIA FORESTAL; ECOLOGIE FORESTIERE; ESSAI; FOREST BORDERS; Forest canopy; FOREST ECOLOGY; Forest regeneration; FOREST TREES; FORESTS; FORET; FRUIT DROP; Fundamental and applied biological sciences. Psychology; HOUPPIER; Neighborhoods; PANAMA; Plant ecology; PRUEBAS; Tree crowns; TREE ORIENTATION; Tree trunks; Trees; TRIALS; Tropical forests; WINDFALLS; Panama, Barro Colorado I; Tree; Crown; Forests; Population dynamics; Asymmetry; Canopy
• ISSN: 0012-9658; 1939-9170
• DOI: 10.2307/1941119

Gap-edge trees were significantly more likely to fall into pre-existing gaps than in other directions in a moist tropical forest on Barro Colorado Island (BCI), Panama. Trees not at gap edges were more likely to fall away from near neighbors than toward them. We show that gross asymmetries of tree crowns were the rule rather than the exception for all trees. The crowns of most gap-edge trees were strongly asymmetrical into their adjoining gaps, and trees not at gap edges were strongly asymmetrical way from near neighbors. Trees had a strong and significant tendency to fall on these heavy sides. Such treefalls, and related limbfalls, can result in redistribution of gaps and a retardation of gap regeneration. An analysis of 5 yr of canopy height data from a mapped 50-ha plot on BCI revealed that sites within larger gaps were significantly more likely to be redisturbed by secondary treefalls than were sites in the smallest gaps or nongap quadrats. These results suggest that treefall gaps in tropical forest may be more persistent disturbances than previously thought.