Seed to seedling transitions in successional habitats across a tropical landscape |
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| Authors: | Marinés de la Peña‐Domene Henry F. Howe Emiliano Cruz‐León Rita Jiménez‐Rolland Cesar Lozano‐Huerta Cristina Martínez‐Garza |
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| Affiliation: | 1. Dept of Biological Sciences, Univ. of Illinois at Chicago (m/c 066), Chicago, USA;2. Depto de Ecología Evolutiva, Centro de Investigación en Biodiversidad y Conservación (CIByC), Paisajes Manejo Integrales A.C., Univ. Autónoma del Estado de Morelos, Morelos, México;3. Facultad de Ciencias, Univ. Nacional Autónoma de México, México, Mexico;4. Dept of Mathematics, Univ. of Chicago, Chicago, IL, USA;5. Inst. de Matem ticas, Univ. Nacional Aut noma de M xico, Campus Oaxaca, M xico;6. Dept of Mathematics, Statistics and Computer Science, Univ. of Illinois at Chicago, Chicago, IL, USA |
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| Abstract: | Recognition that tree recruitment depends on the balance between seed arrival and seedling survival has led to a surge of interest in seed‐dispersal limitation and seedling‐establishment limitation in primary forests. Virtually unaddressed are comparisons of this balance in mature and early successional habitats. We assessed seed rain and seedling recruitment dynamics of tree species in primary forest, secondary forest and pasture released from grazing in a tropical agricultural landscape. Seed to seedling ratios (seed effectiveness; Φi) for 43 species in southern Mexico determined differences in the extent to which seeds produced seedlings by habitat, life history, and dispersal mode. Reproductive potential as estimated by the transition from seed rain to seedling recruitment, differed by habitats, and varied dramatically by life history and dispersal mode. Expected recruit densities (Eit) were higher for animal‐dispersed than wind‐dispersed species, and for non‐pioneer than pioneer species. Non‐pioneers and animal‐dispersed species had higher expected relative recruit abundance (εit) in primary forest (median of 4 seeds recruit?1) whereas in secondary forest wind‐dispersed pioneers had the highest expected relative recruit abundance (median of 16 seeds per recruit). In pastures, wind‐dispersed pioneer species were most successful with many more seeds per recruit (median of 291) than both forest habitats. Seeds per recruit (Φi) appeared to decrease with increase in seed mass for 43 species for which data were available (r = –0.55, P < 0.001). This was associated with a negative correlation of Φi with seed size in primary forest (r = –0.50, P = 0.08 for 13 species); Φi was not correlated with seed size in secondary forest (n = 16) or pasture (n = 14). Metrics of seeds per recruit, expected recruit density and expected relative recruit abundance dramatically illustrate differences in barriers to recruitment in successional habitats. |
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