Seed size and seedling emergence: an allometric relationship and some ecological implications |
| |
Authors: | W J Bond M Honig K E Maze |
| |
Institution: | (1) Department of Botany, University of Cape Town, Private Bag, Rondebosch 7700, South Africa e-mail: bond@botzoo.uct.ac.za, Fax: +27-21-6504041, ZA |
| |
Abstract: | We develop a geometric model predicting that maximum seedling emergence depth should scale as the cube root of seed weight.
We tested the prediction by planting seeds from 17 species ranging in weight from 0.1 to 100 mg at a variety of depths in
a sand medium. The species were spread across 16 genera and 13 families, all occurring in fire-prone fynbos shrublands of
South Africa. Maximum emergence depth was found to scale allometrically with seed weight with an exponent of 0.334, close
to the predicted value. We used the allometry to predict recruitment response to experimentally simulated variation in fire
intensity. Five species with small (<2 mg) seeds and five with large (>10 mg) seeds were planted at ≤20-mm and 40-mm depths
and exposed to low and high heat treatments and a control. The allometric equation predicted that species with large seeds
would be able to emerge from a depth of 40 mm but those with small seeds would not. Only 1% of 481 seedlings from small-seeded
species emerged from the 40-mm planting compared with 40% of 626 seedlings from the large-seeded group. The simulated fire
treatments killed seeds in shallow, but not deeper, soil layers. At simulated high fire intensities, seedling emergence was
poor in small-seeded species but good in large-seeded species, with most seedlings emerging from the 40-mm planting depth.
Seed size could be a useful general predictor of recruitment success under different fire intensities in this system. We suggest
that allometric relationships in plants deserve wider attention as predictive tools.
Received: 28 September 1998 / Accepted: 3 March 1999 |
| |
Keywords: | Seed size Allometry Mediterranean-type shrublands Fire response |
本文献已被 SpringerLink 等数据库收录! |
|