Nitrogen And Phosphorus Rhizosphere Effect: A Potential Strategy Of Phyllostachys Edulis Expansion To Broad-leaved Forest

Phyllostachys edulis expansion has imposed great effects on community structure,species composition and biodiversity in evergreen broad-leaved forest, and mechanisms ofthis phenomenon is complexity. Nitrogen (N) and phosphorus (P) are macronutrientsrequired by plants, and rhizosphere effect is a key pathway by which plants acquire thesenutrients. So, here we assumed the rhizosphere effect of N or P is one of mechanisms forPh. edulis expansion. We conducted a field study by selecting typical transects with Ph.edulis forest, bamboo-broadleaved mixed forest and broad-leaved forest in DagangshanMountain, Jiangxi Province, China. On the basis of community survey, we determined andcompared the available nitrogen and different forms of phosphorus in the soils ofrhizosphere and non-rhizosphere. The results were as following:1. The speed of Phyllostachys edulis expansion to adjacent evergreen broad-leaved forestwas1-2m·a-1, the abundance and growth of Castanopsis fargasii, Castanopsis sclerophylla,Alniphyllum fortunei, Maesa japonica, Dryopteris redactopinnata were influenced.2. When Ph. edulis invaded into bamboo-broadleaved mixed forest, the content ofammonium(NH4+-N), nitrate (NO3--N) and inorganic-N in the rhizosphere soil of bamboorhizome root and base root decreased by15.5%,17.0%,9.8%and31.0%,20.0%,26.5%,respectively. But the rhizosphere effect of base root of bamboo for NH4+-N andinorganic-N increased by56.6%and30.7%, respectively, and rhizome root of bambooincreased by23.9%and19.5%, respectively. Rhizosphere effect of NO3--N was almostunchanged.3. When Ph. edulis invaded into bamboo-broadleaved mixed forest, the content of total Pchanged with no significant differences. But the rhizosphere effect and content of availableP in base root and rhizome root of bamboo increased. And the content of available P were21.22mg·kg-1,20.84mg·kg-1in Ph. edulis forest, and22.45mg·kg-1,24.11mg·kg-1afterPh. edulis expanded. The rhizosphere of available P were1.33,1.31in Ph. edulis forest,and1.68,1.80after Ph. edulis invaded.4. Affected by Ph. edulis invasion, the rhizosphere effect of NH4+-N of Castanopsisfargasii, Castanopsis sclerophylla, Alniphyllum fortunei, Maesa japonica, Ardisia crenata,Dryopteris redactopinnata decreased in the late stage of competition, while RhizomaCibotii unchanged.5. When Ph. edulis expansion into bamboo-broadleaved mixed forest, the rhizosphereeffects of the same plants for the different nutrients were different. The rhizosphere effectsof N of bamboo rhizome root and base root were49.4%and71.1%higher than that of P,respectively. 6. The rhizosphere effects of NH4+-N, inorganic-N and available P of Ph.edulis forest andbamboo-broadleaved mixed forest were higher than the competing species.Above results suggested that Ph. edulis rhizosphere effect was more obvious thanother plants, and the rhizosphere effects of other plant were of difference respond to Ph.edulis expansion, this may be one of potential strategies for Ph.edulis expansion intoadjacent forests, and changes in community structure and species diversity.