Revista Chilena de Historia Natural 81 (2): 257-266, 2008
RESEARCH ARTICLE
Responses of two temperate evergreen Nothofagus species to suddenand
gradual waterlogging: relationships with distribution patterns
The effects of gradual waterlogging on trees have been little studied. The temperate
evergreens Nothofagus nitida and N. dombeyi are differentially distributed on soil moisture gradients, only the
former being common on poorly-drained sites. We compared the relative height growth rate
(RGR<sub>H</sub>) and foliage loss of seedlings subjected experimentally to normal drainage (soil at field
capacity), sudden waterlogging and gradual waterlogging for two months to determine which waterlogging regime more
accurately predicts interspecific differences in tolerance, as evident from natural distributions.
RGR<sub>H</sub> was similar between species but differed between treatments (normal watering > gradual
waterlogging = sudden waterlogging). Sudden waterlogging caused massive foliage loss in the two species, but gradual
waterlogging caused much greater foliage loss in N. dombeyi than in N. nitida, indicating some degree of
acclimation by the latter species. Linear regressions indicated that RGR<sub>H</sub> was negatively affected
by foliage loss in both species, without differences between them. Since no difference in RGR<sub>H</sub>
was found between species in the waterlogging treatments, but yet in foliage loss, other mechanisms may be involved in
the short term growth reduction of N. nitida. Effects of waterlogging on long-term performance in the field
were evaluated by reciprocal transplants between a poorly-drained site naturally occupied by N. nitida, and a
well drained site naturally occupied by N. dombeyi. After two growing seasons, N. dombeyi had
significantly lower specific leaf area (SLA) and RGR<sub>H</sub>, at the poorly drained site than at its original
site. At the poorly drained site N. nitida achieved 100 % survival, compared with 73.5 % in N. dombeyi.
Reduced growth and survival of N. dombeyi associated with the negative effects on carbon gain of extensive
foliage loss and reduced SLA may thus exclude it from the wetter sites. We conclude that tolerance may be better
predicted from responses to gradual, rather than sudden waterlogging.
Key words:
Nothofagus, reciprocal transplants, seedling growth, temperate rainforest
