Abstract: In order to further understand the effects of acid rain and herbicide on soil fauna of urban lawn, a field experiment was conducted including three simulated acid rain acidity (pH 4.5, 3.5 and 2.5), three herbicide application levels (Starane volume fraction of 0.1%, 0.2% and 0.4%), and their compound treatments. Urban lawns were selected as the experiment plots for three months. It was shown that the density and group number of macrofauna and meso-micro fauna (Tullgren method) decreased after adding acid rain and herbicide, but the density of meso-micro fauna (Baermann method) increased with acid rain acidity. Under combined stress, acid rain and herbicide had significant (P<0.05) interactions on soil macrofauna and meso-micro fauna (Tullgren method). However, interactions on meso-micro fauna (Baermann method) were not obvious. The relationship between soil fauna density and pollutant intensity was complicated. Soil fauna, represented by Araneae, Collembola and Nematoda, had different responses to the same pollution intensity. The diversity indices of soil fauna community were different among treatments. Shannon-Wiener index and Pielou index increased with the herbicide application level, while decreased with the increasing acidity of acid rain. Overall, under the stress of acid rain and herbicides, the density, even the group number of soil fauna would decline to some extent, and the trend would vary with the intensity of pollutants and the groups of soil fauna.

Key words: simulated acid rain, herbicides, soil fauna, urban lawn, compound stress