Lawns dominate urban land cover in the U.S. and require intensive management, including frequent mowing. Lawn mowing may increase ecosystem disservices such as carbon dioxide (CO2) emissions from both biogenic and anthropogenic sources, as well as contact with Lyme disease-carrying tick vectors from taller grass. Thus, decision makers in urban areas actively pursue strategies to minimize these disservices by decreasing CO2 emissions and other greenhouse gases and identifying opportunities to mitigate contact with ticks to combat an important public health issue. We tested whether changes in lawn mowing frequency could act as one of these strategies. We assigned sixteen yards in Springfield, Massachusetts USA to a mowing frequency (every 1-, 2-, or 3-weeks). We used a mixed effects modeling approach to test how soil respiration (i.e., biogenic CO2 emissions), gasoline emissions associated with lawn mowing (i.e., anthropogenic CO2 emissions), and tick abundance responded to mowing frequency and interacted with changes in soil moisture, temperature, canopy cover and grass height.
Results/Conclusions
Lawn-mowing frequency did not influence soil temperature, moisture, or biogenic soil CO2 fluxes. Soil microclimate and soil respiration varied more with ambient climatic fluctuations and tree canopy cover, with higher canopy cover resulting in cooler soils and lower biogenic CO2 fluxes. By contrast, anthropogenic emissions increased with more frequent mowing due to emissions associated with the mower itself. When scaled to the entire mowing season, biogenic CO2 fluxes far exceeded the anthropogenic fluxes, thus requiring consideration for accurate accounting in urban greenhouse gas emissions inventories. Although grass height was significantly taller in lawns mowed less frequently, we failed to detect any ticks. We recognize that Lyme disease and other tick-borne diseases represent a serious health risk, however, recommendations to mow lawns frequently and short could have minimal impacts on tick microhabitats while negatively affecting beneficial wildlife and other ecosystem services associated with urban biodiversity. Residential landscape design in general and lawn mowing specifically is largely driven by aesthetics. Thus, quantifying the balance between satisfying societal preferences for lawns and their associated maintenance against the need to plant trees to counteract biogenic soil CO2 emissions of lawns, reduce mowing frequency to minimize anthropogenic emissions associated with the mower itself, and acknowledge the limitations for protecting against ticks via frequent mowing is essential to develop evidence-based strategies for preventing ecosystem disservices in urban residential areas.