Preliminary Studies on Microbial Biomass and the Microarthropod Community as Soil Health and Quality Indicators in Urban Grasslands, Rīga as an Example / Sākotnējie Pētījumi Par Augsnes Mikrobiālo Biomasu Un Augsnes Sīkposmkāju Sabiedrībām Kā Augsnes Veselības Un Kvalitātes Indikatoriem Rīgas Pilsētas Urbānajos Zālājos

Anthropogenic pollution is considered as a one of the main factors that affects soil in urban areas. In 2014, soil quality of grasslands in Rīga was determined. The aim of the study was to determine microbial biomass and describe microarthropod communities in soils of different grasslands in Rīga city and to assess their use as indicators of soil health and quality of the urban environment. Six sampling plots with different building characteristics, density of street and rail network and transport load, and potential impact of pollution were selected for studies. The substrate-induced respiration method was used for determination of soil microbial biomass. Soil invertebrates were collected in sampling plots. Soil Mesostigmata mites, Oribatida and Collembola were extracted from samples and counted. In total over 9300 soil microarthropod individuals were recorded, of them 4500 Collembola, 3400 Oribatida and 1400 Mesostigmata mites. Statistically significant differences in soil microbial biomass among sampling sites were observed. Soil microbial carbon content significantly increased in most of sampling plots from July to October. To obtain more precise results in the future some modifications and optimisation of the standard method based on indicators will be necessary.