Strong interactions between microclimate and dormancy release have important implications for the population dynamics of tropical plants at a range of scales. In tropical and arid regions, bare patches are common at the plant size scale, such as between grass tussocks and under trees following canopy death (Ludwig et al., 2003). At this scale, altered microclimate is a likely explanation for the frequently observed mass germination events following the death of parent trees of P. aculeata (R. D. van Klinken, unpubl. res.), and provides an alternative hypothesis for germination suppression such as allelopathy (Hierro and Callaway, 2003), low light (Denslow et al., 1990) and fluctuating high temperatures (McKeon and Nott, 1982). Significant microclimate effects are also likely to be seen at a landscape scale. For example, it would be expected that seed bank longevity, resulting from low rates of dormancy release, would be greatest in heavily vegetated habitats, and in wetlands where seeds may be essentially buffered by water for long periods. There are, however, insufficient data to speculate as to whether dormancy release through wet heat is expressly calibrated to respond to environmental signals, as is the case for some other dormancy release mechanisms (Baskin and Baskin, 1998).
Tropical Heat (1993): Download Movie
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