Populations of American beech in Virginia and the Great Smoky Mountain National Park in Tennessee and North Carolina were investigated for demographic genetic substructurings. Two Virginia populations, one on the Blue Ridge (WG1) and the other on the Piedmont (WG2) occur over an elevational gradient of several hundreds meters. One of the Great Smoky Mountain populations (GS1) was in a ‘beech gap’ and the other (GS2) in a ‘cove forest’ along a creek. The populations in the Great Smoky Mountain National Park were only separated by a few hundred meters in elevation, but both on the same physiographic province. The populations had two growth forms. Trees produced extensive root suckers at WG1, GS1 and GS2, but WG2 had no root suckers and all individuals had obviously been established from seeds. A total of 1335 shoots were mapped at the four sites, their size measured [diameter at breast height (DBH) or diameter at ground height (DGH)], and genotypes were determined for each locus using allozyme analysis. FIS among five different size‐classes revealed an excess of homozygotes in WG1, GS1 and GS2, and an excess of heterozygotes in WG2. The offshoot formation from root suckers obviously contributed to the abundance of intermediate size‐classes in WG1, GS1 and GS2. Exceedingly localized patchiness of different multilocus genotypes reveals genetic clustering of shoots that have obviously originated from root suckers in WG1, GS1 and GS2. The Piedmont population (WG2), on the other hand, showed loose localization of genetically related trees at a scale of 35–40 m in area, suggesting broader ranges of pollen and seed dispersal. The data are discussed in the light of the differences in growth form and mode of reproduction, and also in relation to the post‐glacial migration and the current geographic distribution of the species.

Genetic recovery of an American beech (Fagus grandifolia) population in deciduous forests that were once pastures was studied using 16 allozyme loci from 410 individuals in a 600 m ¥ 600 m study plot in Maryland, USA. We also examined the spatio-temporal genetic structure of the American beech population at a regional scale. Overall genetic diversity of mature trees was measured by estimating average heterozygosity (H = 0.156). Rare alleles were observed in five loci, Lap, 6Pdgh3, Pgi, Adh1 and Got3.

We investigated seed dispersal by wintering birds in an isolated urban green space in Tokyo. Seeds of nine plant species were found in the faeces of eight species of captured birds. The Brown-eared Bulbul Hypsipetes amaurotis, the Dusky Thrush Turdus naumanni and the Japanese White-eye Zosterops japonicus excreted 93% of the seeds, and these birds are dominant in the study site, suggesting that they are important seed dispersers. With the exception of one plant species, all the seeds found in the faeces of the captured birds were from plants growing in the study site, indicating that seeds were only rarely imported from outside of the green space. The faecal samples showed birds to have eaten fruits that were not only smaller but also larger than their gape width. Idesia polycarpa for example had fruits with diameters larger than, and not overlapping with, the gape width of the Red-flanked Bushrobin Tarsiger cyanurus, the Japanese White-eye and the Black-faced Bunting Emberiza spodocephala, indicating that birds can swallow fruits that are larger than their gapes. This finding may be caused by limitation of fruit-size selectivity of birds due to the small area of the isolated habitat and to the end of the fruit season.

No abstract

No abstract