Interactive effects of flooding and treefall gap formation on terra firme forest and várzea forest seed and seedling mechanisms and tolerances in the Ecuadorean Amazon
2014
Myster, R.
The influence of white-water flooding and treefall gap formation on terra firme forest regeneration was investigated in Yasuni National Park of western Ecuador. I set up seed traps, collected seed rain and soil samples, and set out seeds and seedlings in unflooded terra firme forest (dry) and its gaps, and in nearby white-water floodplain várzea forest (wet) and its gaps. I found that (1) total number of dispersed seeds was greatest in the dry gaps with more seeds and greater richness in the gaps than the forest for both forest types, (2) the greatest number of seedlings germinated from wet gap soils with the least from the dry forest with gaps having more seedlings compared to their respective forests, (3) on average 30% of seeds remained after two weeks in the field and species seed losses were significantly different in all but one of the four sites, (4) more large seeds than small seeds were lost to pathogens and those losses were greater in the forests than the gaps, (5) as seed mass increased seedlings survival rates also increased but growth rates declined, and (6) more seedlings survived in gaps compared to closed forests where they grew faster with a larger leaf area ratio. Past sampling has shown that species composition differed between forest types, and present results show that the greatest seed and seedlings losses and the slowest growth rates were in intact terra firme forest, there were medium losses and medium growth rates in terra firme gaps and in the intact várzea forest, and the smallest losses and fastest growth rates were found in várzea gaps.
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