Revista Chilena de Historia Natural 82 (2): 185-198, 2009
RESEARCH ARTICLE
Tree regeneration patterns in canopy gaps after a decade of Chusquea quila
(Poaceae) dieback in an old-growth remnant forest in the lake district of south-central Chile
In old-growth forests at low elevations in south-central of Chile (38-42º S), the native
understory bamboo Chusquea quila plays an important role on the establishment and growth of tree species in tree-fall
gaps. Bamboo dieback that occurs after an extensive vegetative period represents a large-scale endogenous disturbance that could
influence tree regeneration dynamics in gaps. The main goal of this study was to analyze the main patterns of the tree regeneration in
canopy gaps in an old-growth remnant forest, 10 years after the bamboo dieback in 1994. Six gaps tree-fall gaps were located and
permanent plots were established to study the demography and growth changes of the advanced regeneration and new recruitments.
These changes were evaluated between the years 1994 and 2003. The advanced regeneration was composed mainly of the shade-
tolerant tree species A. punctatum, L. philippiana and A. luma. Their mortality after 10 years
averaged 42 % and affected mostly individuals originated from seeds. In contrast, individuals of L. philippiana and E.
cordifolia, originated from rootstocks, showed higher growth rates and lower mortality. On the other hand, new recruitment was
characterized by the abundant regeneration of N. obliqua, P. saligna and A. chilensis during the
first season after the dieback; however few individuals of these species survived the competition of the new bamboo cohort. Similarly,
juveniles originated from rootstocks of E. cordifolia, G. avellana and L. philippiana showed higher
growth rates and survivorship than plants originated from seeds. These results suggest that the temporary increase of resources in
canopy gaps, due to the bamboo dieback, would favor tree species of mid-late successional stands, especially those originated from
vegetative reproduction. Pioneer species in these forests such as N. obliqua were not favored by the bamboo dieback in
small gaps (< 1,000 m2), suggesting these species that would depend mostly on large-scale catastrophic
disturbances.
Key words:
regeneration dynamics,
tree-fall gaps, Chusquea quila dieback
