Importance of seed size for the establishment of seedlings of five deciduous broad-leaved tree species

Abstract

Effects of seed size and phenology on the establishment of five deciduous broad-leaved tree species were examined in deciduous woodland. Treatments included absence and presence of litter in the forest understory, a small gap, and a large gap. Seedling emergence of large-seeded species Quercus mongolica var. grosseserrata and Acer mono was not reduced by accumulation of litter in the forest understory, but was promoted in the large gap where litter was less. Seedling emergence of small-seeded species, Alnus hirsuta, Cercidiphyllumjaponicum and Betula platyphylla var. japonica, was reduced by the litter in almost all of the sites. Seedlings of large-seeded species avoid shade stress phenologically by unfolding all of their large leaves in a short period before canopy closure in the forest understory. These species had little mortality after seedling emergence. In contrast, small-seeded species have a longer duration of leaf emergence, shorter leaf longevity, and rapid leaf turnover in all the sites. These seedlings attained similar height to those of the large-seeded species at the end of the second year in the large gap, but survival and height growth rate decreased after canopy closure in the forest understory. We suggest that the importance of seed size in determining seedling establishment largely depends on the relationships between seasonal changes of environmental conditions and phenological traits of seedlings, which are related to seed size.

Effect of gene flow on spatial genetic structure in the riparian canopy tree Cercidiphyllum japonicum revealed by microsatellite analysis

“…Seeds that disperse longer distances may have higher survival probabilities than those near maternal trees because they escape the mortality caused by density-dependent processes such as competition, predation, and disease (Janzen, 1970;Clark and Clark, 1984). In the case of C. japonicum, seedlings that germinate under the crown of a mature tree cannot survive because the light conditions are not suitable for establishment (Seiwa and Kikuzawa, 1996;Kubo et al, 2000). The preferred site for C. japonicum seedlings is bare ground formed by infrequent, large disturbances such as floods with debris avalanches (Kubo et al, 2000), and seed shadows may overlap at such disturbed sites.…”

“…The species is dioecious and wind-pollinated, flowering in early spring before the leaves shoot. Its seeds are winged, wind-dispersed and approximately 6 mm in length and 2 mm in width (Kubo et al, 2000), with an average weight of 0.667 mg (Seiwa and Kikuzawa, 1996). Current-year seedlings reach only approximately 1.5 cm in height, emerging from bare soil on steep slopes, rocky ground and fallen logs, but most die within a year (Kubo et al, 2000).…”

Assessing the potential of natural woody species regeneration for the conversion of Norway spruce plantations on alluvial soils

“…I) leads to a greater part of mineral soil being exposed to the seed-rain, providing an ideal substrate for germination and growth of not only small-seeded, wind-dispersed species [20] such as Alnus glutinosa and Salix spp., but also large-seeded species such as F. excelsior, A. pseudoplatanus, Q. robur and F. sylvatica. Moreover, seedling emergence of small-seeded species is inhibited by litter to a much higher extent than that of large-seeded species [20,52]. This may explain why the main regenerating tree species are large-seeded species (Fig.…”

Regeneration dynamics, population structure, and forest composition in some ridge forests of the Western Himalaya, India

“…The topographic position maintains seedling establishment in temperate forests and determines the species composition on ridge tops. Seiwa and Kikuzawa (1996) and Seiwa (1997) have also reported that seedling survival is often inhibited by water deficit and litter accumulation. Low seedling density at mid altitudes (1800-3230 m a.s.l.)…”