Seed dispersal by frugivorous birds in Nanjing Botanical Garden Mem. Sun Yat Sen in autumn and winter
LI Xin-Hua, YIN Xiao-Ming, HE Shan-An
Biodiv Sci. 2001, 09 (1):
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Nanjing Botanical Garden Mem. Sun Yat-Sen is located in the southern foot of Zhongshan Mountain. Avian frugivores such as Turdus merula, Pycnonotus sinensis, Garrulax perspicillatus, Cyanopica cyana, Streptopelia orientalis and Turdus naumanni feed mainly on tree fruits in the garden during autumn and winter. One hundred and sixty samples of birds faeces were randomly collected within the garden from October 20, 1999 to January 20, 2000. Totally 874 intact seeds, which were generally enclosed by a hard seed coat or by hard endocarp,three pieces of insect remnants of Coleoptera and one remnant of bird were found in these birds' faeces. Among the seeds, 842 have been identified as belonging to 26 plant species of 20 genera and 16 families. Plant species comprising the highest percentage in frequency in the 160 samples of birds' faeces are Ilex purpurea(22.2%), Sabina chinensis(11.1%), Rhus chinensis(10.6%), Celtis sinensis(9.2%), Parthenocissus tricuspidata (7.7%) and Sabina chinensis cv. kaizuca(7.3%). Plant species with highest percentage of seed number in the samples are Ilex purpurea(23.5%), Rhus chinensis(16.2%), Sabina chinensis(13.5%),Parthenocissus tricuspidata(8.0%), Sabina chinensis cv. kaizuca(8.0%)and Rosa cymosa(5.3%). Avian frugivores may disperse from the parent trees by (i) ingesting fruits around the parent trees, then defecating or regurgitating the seeds away from it, or (ii) picking the fruits up away from the parent trees. Both fecal borne seeds, such as Rhus chinensis and Parthenocissus tricuspidata, and regurgitated seeds, such as Cinnamomum camphora and Melia azedarach, were viable to produce seedlings based on a preliminary germination test. Seedlings of Cinnamomum camphora,Ilex purpurea, Pittosporum tobira, Taxus chinensis and some other trees cultivated in the garden have successfully invaded into a natural Pinus thunbergii Liquidambar formosana community on a hillside at the edge of the garden and into a natural Pterocarya stenoptera-Celtis sinensis community beside a mountain stream through the garden, as a result of seed dispersal by frugivorous birds. Avian seed dispersers have spread the distribution of some cultivated fleshy fruiting species in the botanical garden and have promoted their natural regeneration.