Ecology of seed germination of eight non-pioneer tree species from a tropical seasonal rain forest in southwest China |
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Authors: | Yang Yu Jerry M Baskin Carol C Baskin Yong Tang Min Cao |
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Institution: | (1) Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, 650223, China;(2) Graduate University of Chinese Academy of Sciences, Beijing, 100049, China;(3) Department of Biology, University of Kentucky, Lexington, KY 40506-0225, USA;(4) Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546-0312, USA |
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Abstract: | We compared various aspects of the seed biology of eight non-pioneer tree species from a tropical seasonal rain forest in
Xishuangbanna, SW China, that differ in time of dispersal, size and fresh seed moisture content (MC). Seeds were tested for
germination under laboratory conditions after dehydration to different moisture levels and under 3.5, 10 and 30% solar irradiances
in neutral-shade houses. For six species, germination was also compared in forest understory (3.5% light) and center of a
forest gap (32.5% light). Under continuous dehydration over activated silica gel, 100% of seeds of four species had lost the
ability to germinate after 48 h, and those of all species except Castanopsis hystrix (decreased from >90 to 30% germination) had lost the ability to germinate after 120 h. Four species did not differ in final
germination percentages at the three irradiances (i.e. uniform germination). However, final germination percentages of Horsfieldia pandurifolia and Litsea pierrei var. szemaois were significantly lower in 30% than in 10 or 3.5% light, and seeds of Antiaris toxicaria and C. hystrix germinated to higher percentages in 30 and 10% than in 3.5% light. Mean time to germination (MTG) of the eight species (forest
and shade house data combined) ranged from 5–5 days for Pometia
tomentosa to 72–207days for L. pierrei; MTG for four species was ≤21 days. There was no obvious relationship between relative desiccation resistance and either
time of dispersal, MTG or uniformity of germination at the three light levels, or between seed size and MC or MTG. However,
the relationship between seed MC at maturity (25–60% fresh mass basis) and MC at 50% loss of seed viability (12.4–42.5%) was
significant. Seven of the species fit Garwood’s (Ecol Monogr 53:159–181, 1983) rapid-rainy germination syndrome and one, L. pierrei, either her delayed-rainy or intermediate-dry germination syndrome. However, fresh, non-dehydrated seeds of all eight species
germinated in ≤30 days at constant 30°C in light. |
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Keywords: | Desiccation-sensitive seeds Forest gap Forest understory Fresh seed moisture content Seed dispersal Seed germination Seed light response Seed size |
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