Short dry spells in the wet season increase mortality of tropical pioneer seedlings
| Autor: | David A. Galvez, Tobias Koehler, Melvin T. Tyree, Thomas A. Kursar, James W. Dalling, Tim Pearson, Bettina M. J. Engelbrecht, Robert L. Wolf |
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| Rok vydání: | 2005 |
| Předmět: |
Wet season
Irrigation Tropical Climate Pioneer species biology Ecology Panama Water Evergreen biology.organism_classification Cecropia Plant Soil Deciduous Agronomy Habitat Seedling Seedlings Tropical climate Bombacaceae Melastomataceae Tiliaceae Piper Weather Ecology Evolution Behavior and Systematics |
| Zdroj: | Oecologia. 148(2) |
| ISSN: | 0029-8549 |
| Popis: | Variation in plant species performance in re- sponse to water availability offers a potential axis for temporal and spatial habitat partitioning and may therefore affect community composition in tropical for- ests. We hypothesized that short dry spells during the wet season are a significant source of mortality for the newly emerging seedlings of pioneer species that recruit in treefall gaps in tropical forests. An analysis of a 49- year rainfall record for three forests across a rainfall gradient in central Panama confirmed that dry spells of ‡10 days during the wet season occur on average once a year in a deciduous forest, and once every other year in a semi-deciduous moist and an evergreen wet forest. The effect of wet season dry spells on the recruitment of pioneers was investigated by comparing seedling sur- vival in rain-protected dry plots and irrigated control plots in four large artificially created treefall gaps in a semi-deciduous tropical forest. In rain-protected plots surface soil layers dried rapidly, leading to a strong gradient in water potential within the upper 10 cm of soil. Seedling survival for six pioneer species was sig- nificantly lower in rain-protected than in irrigated con- trol plots after only 4 days. The strength of the irrigation effect differed among species, and first became apparent 3-10 days after treatments started. Root allocation patterns were significantly, or marginally significantly, different between species and between two groups of larger and smaller seeded species. However, they were not correlated with seedling drought sensitivity, sug- gesting allocation is not a key trait for drought sensi- tivity in pioneer seedlings. Our data provide strong evidence that short dry spells in the wet season differ- entially affect seedling survivorship of pioneer species, and may therefore have important implications to seedling demography and community dynamics. |
| Databáze: | OpenAIRE |
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