Community Survey Of Extrafloral Nectaried Plants In Tropical Rainforest In Xishuangbanna, Yunnan Of China

Extrafloral nectary (EFN) is the nectary that locates outside the flower, usually on the leaf, stem, calyx or outboard of petal, and usually has no direct relationship with pollination. EFN plants'abundance among different communities, different life forms and different layers always attracts attentions from scientists. Xishuangbanna southwest of Yunnan is biogeographically located at a transitional zone from tropical southeast (SE) Asia to subtropical east Asia and is at the junction of the Indian and Burmese plates of Gondwana and the Eurasian plate of Laurasia. Here has a special tropical flora, however, no study about EFN plants were carried out in this region. The author carried out investigations in three pristine rainforests and four secondary forests with different ages. Main work include:(1) Investigation of EFN angiosperm plants in each communities;(2) Comparision of EFN species abundance among different aged forest communites, different life forms in the seven communities and different layers in the three pristine rainforests;(3) Comparision of the differences of herbivory and EFN among different growth stages of Cleidion bracteosum, Dichapetalum gelonioides, Pometia tomentosa, three common EFN trees.Main results include:(1) Fifty-two species belonging to 36 genera and 23 families accounting for 12.3% of 424 angiosperm species were found bearing extrafloral nectaries (EFNs). Among them eight genera and 37 species were the first time to be reported bearing EFNs. Further analysis revealed that EFN-bearing species were concentrated in subclasses (Dilleniidae, Rosidae, Asteridae) of the Magnoliopsida. And most common EFNs were flattened glands grown on leaf blades;(2) The abundance of EFN-bearing angiosperm plants within the seven communities ranged from 9.5% (Vatica guangxiensis forest) to 18.5% (Macaranga denticulate forest). And EFN-bearing species appeared to be more abundant in the secondary forests than in primary forests;(3) EFN-bearing species were disproportionally distributed among different life forms and the abundance sequence was: tree>shrub>liana>herb. There were no epiphytes and parasite plant bearing EFNs, and this might be a result of different group of plants distributed in a region.(4) In the three pristine rainforest communities, we found the same pattern as that appeared in different layers in a pristine forest of Pasoh (Malaysia) that the EFN plants abundance was highest in the first layer or canopy, lower in the third layer, much lower in the second layer, lowest in the shrub layer, thought, the differences was not significant (F3,11=1.041, P=0.425);(5) Herbivory of the three species between young saplings and saplings was the same, but different between seedlings and sapling. Herbivory was higher in saplings than seedlings of C. bracteosum and P. tomentosa, but we got an opposite pattern in D. gelonioides;(6) EFN number per leaf and per m2 of leaf of the three species between young saplings and saplings was the same, but different between seedlings and saplings. EFN per leaf of C. bracteosum between seedlings and saplings was the same, but different in D. gelonioides and P. tomentosa. EFN per m2 of leaf of D. gelonioides between seedlings and saplings was the same, but different in C. bracteosum and P. tomentosa;(7) Totally we captured more than 122 capital, 35 species of ants, they belonged to 35 genera. And more than 25 capital (9 species, 9 genera) were found at C. bracteosum, more than 19 capital (7 species, 6 genera) at D. gelonioides, and more than 75 capital (21 species, 11 genera) at P. tomentosa.In all, Tropical rainforest in Xishuangbanna was relatively abundant with EFN plants and related ant fauna. EFN plants seemed more abundant in secondary forest than in primary forest. EFN plants abundance among different life forms was different, and this might be a result of different group of plants distributed in a region. EFN plants abundances in different layers of primary forest seemed different, and this might be a interactive result of light environment and herbivory. Among growth stages, EFN and herbivory variations showed different patterns, but we did not find a relationship between EFN variation and herbivory variation.