Invertebrate fauna associated with mulch in urban environments

Abstract An inventory of invertebrates associated with different types of mulches in central Ohio revealed that significantly more organisms occurred in mulched plots than in bare soil plots. Mulch often harbored more than twice as many organisms as bare soil. Furthermore, these invertebrates were more prevalent in the mulch itself than in the underlying soil. The compass side of the structure and the type of groundcover appeared to have little effect on the numbers of invertebrates in plots (groundcover and underlying soil). Collembola and acarines were present in more than half of the plots, often in very high numbers. Diplopods were the most plentiful macroarthropod, occurring in almost half (48.9%) of the plots. Other regularly encountered invertebrates included isopods, coleopterans, nematodes, chilopods, and earthworms. Isopterans, psocids, aranids, formicids, symphylans, diplurans, and dermapterans were occasionally encountered. Some organisms were more prevalent in a particular type of mulch, i.e., isopods in leaf litter; acarines and diplopods in hardwood mulch; pseudoscorpions, diplopods, and acarines in pine bark micro-nuggets; and symphylans in grass. Inorganic mulches tended to hold less moisture and harbored fewer invertebrates than organic mulches. Diplopods, earthworms, isopods, collembola, acarines, dipteran larvae, pseudoscorpions, psocids, aranids, and isopterans were found in significantly higher numbers at a mulch depth of 11 to 13 cm. Most invertebrates were present in significantly lower numbers at a mulch depth of 1 cm. Isopterans experienced a significant decrease in numbers at a soil temperature of 22°C, which was an ideal temperature for dipteran larvae, diplurans, pseudoscorpions, and symphylans. There was a dramatic drop in numbers of all invertebrates except psocids when the surface temperature reached 34°C. Key Words Arthropods, nematodes, termites, soil temperature, soil moistur