Clonal Integration And Vegetation Inside Clones Of Iris Delavayi

Clonal plants are widely distributed in various ecosystems and have profound effects on species composition and diversity of plant communities. Effects of clonal integration have been extensively studied in guerilla clonal plants, but those in phalanx clonal plants have rarely been tested. Also, there is little information about plant species composition and soil nutrient contents inside clones of phalanx clonal plants. A controlled field experiment was carried out to test the effects of clonal integration on tolerance to defoliation in a phalanx clonal plant Iris delavayi. Furthermore, a field survey was conducted to examine plant species composition and diversity and soil nutrient contents inside and outside the clones (tussocks) of I. delavayi. Defoliation (simulated herbivory) significantly decreased leaf biomass and number of ramets of I. delavayi, and such negative effects of defoliation were reduced by clonal integration (maintaining rhizome connections between ramets). Defoliation induced compensatory growth of I. delavayi and clonal integration increased such an effect. Vegetation inside and outside clones of I. delavayi differed greatly, and plant species richness, pooled cover and Shannon-Wiener diversity index were significantly higher outside than inside the clones. Five plant species with frequency of<10% were only distributed inside clones of I. delavayi, but no plant species with a higher frequency occurred more inside than outside the clones. Total nitrogen content did not differ significantly between soils inside and outside the clones, whereas total phosphorous content was significantly greater in soils inside than outside the clones. Therefore, clonal integration can enhance tolerance of phalanx clonal plants to herbivory and clones of phalanx plants can affect fine-scale spatial heterogeneity in the distribution of phosphorous in soils, but can not induce the species diversity inside the clones. There is little evidence that some species can thrive better inside than outside tussocks of I.delavay.