Dispersal phenology of hydrochorous plants in relation to discharge, seed release time and buoyancy of seeds: the flood pulse concept supported

Abstract

Summary1 Restored floodplains and backwaters lacking a viable propagule bank, may need flood pulses to facilitate inward dispersal of diaspores. Temporal patterns of hydrochorous plant dispersal are, however, not well known. 2 Diversity and abundance of diaspores dispersed in a water body over 12 months were quantified using a 200 µ m net in order to: (i) test for a relationship between discharge and the number of species and diaspores dispersed; (ii) examine the effect of seed buoyancy and seed release period on the length of the dispersal period; and (iii) test whether diaspores of species that disperse during a similar period of the year are characterized by similar dispersal and dormancy traits. 3 A total 359 188 individuals of 174 vascular species developed from 144 samples, with most (90%) from vegetative diaspores and only 10% from seeds. Mean number of species and diaspores varied between months in parallel with discharge levels. Stepwise multiple regression analysis showed that both seed buoyancy and seed release influenced dispersal periods. 4 In general, species that dispersed most diaspores in spring and summer had nondormant seeds, a shorter seed release period and a shorter seed dispersal period than species whose dormant seeds dispersed in autumn and winter. Vegetative diaspores were dispersed on average over 8 months, indicating their importance to long-distance dispersal. Several species dispersed both generative and vegetative diaspores, often in different seasons. 5 Our results may assist the planning of regenerative processes in riverine wetlands at landscape scales, as dispersal phenology, and discharge rates must be taken into consideration. Vegetative diaspores may be more important than seeds, although the latter may extend the species dispersal period into other seasons. Temporal heterogeneity in diaspore dispersal influences the identity of diaspores reaching restored habitats.

Fruiting phenology affected by seed preference and fluctuation of seed predator activity in a Tropical Peat Swamp Forest

“…Similar fruiting during periods of high water has been observed in Amazonian floodplain forest (Haugaasen and Peres 2005), where it is regarded as a phenological adaptation associated with hydrochorous trees (i. e. trees with water buoyant seeds) (Boedeltje et al 2004). In the present study, seeds of the two Calophyllum species do appear to be hydrochorous: both produce seeds that have a thin, protective shell, surrounded by a spongy layer that makes them buoyant in water.…”

Potential for the development of submerged macrophytes in eutrophicated shallow peaty lakes after restoration measures

“…Some of these species probably re-established from soil seed banks, such as Characeae, which are known to have persistent seed banks (Thompson et al, 1997). Transport of diaspores by water is also known to play an important role in the establishment of submerged macrophytes, especially E. nuttallii and C. demersum (Boedeltje et al, 2003(Boedeltje et al, , 2004. Birds are known to transport propagules of aquatic plants frequently, at least at a local scale, both by endozoochory (internal transport of seeds, e.g.…”

Dispersal by cattle of salt-marsh and dune species into salt-marsh and dune communities

“…If significant differences were found, these were tested using Dunnett's T3 test due to nonhomogeneity of variances. To assess significant temporal patterns of individual species, repeated measures analyses were performed (see Boedeltje et al 2004). A total of 25 species were included, those which had [10 records in at least two of the sampling periods.…”