Abstract: Ammonia volatilization makes a vital contribution to the formation of atmospheric haze. However, the effect of plant diversity on ammonia volatilization is still unknown in biodiversityecosystem functioning researches. This study conducted a microcosm experiment simulating constructed wetlands. Two species, Cichorium intybus L. and Rumex japonicus Houtt., were used to set two monoculture treatments and a mixture treatment (the basic model to test diversity effect). Ammonia volatilization flux was measured in initial stage (with hydraulic retention time of 1 day) and later stage (with hydraulic retention time of 7 days) after the simulated wastewater was supplied. The results showed that: (1) ammonia volatilization from the mixture treatment was lower than the average of that from the two monocultures (for 1 day, P<0.05; for 7 days, P=0.068); (2) ammonia volatilization from R. japonicus monoculture was lower than that from C. intybus monoculture (for 1 day, P<0.05; for 7 days, P=0.062); (3) plant diversity had a stronger suppression effect on ammonia volatilization in initial stage than that in later stage of wastewater feeding; (4) species identity had a greater effect on ammonia volatilization and related ecosystem functioning than species richness. This study suggests that assemblage of appropriate key species is beneficial to improving the ecosystem functioning in constructed wetlands.

Key words: agriculture, risk evaluation, basin area of Sichuan Province., autumn continuous rain