Baltimore Ecosystem Study Institute of Ecosystem Studies

2017 BES Annual Meeting Presentation and Poster Abstracts

Conversion of forest soils to lawns increases soil CO2 efflux
Rosier, Carl
Co-Authors: Carl L. Rosier, Joseph Barba, Matthew Patterson, Tara L. E. Trammell, Rodrigo Vargas and John Hom

Abstract: Carbon dioxide (CO2) is an important greenhouse gas, atmospheric concentrations are predicted to increase as forest soils are converted to lawns. Urban lawns may act as a carbon sink offsetting biogenic fluxes. Assessing the seasonal contribution of lawn biogenic CO2 fluxes will improve our understanding of the urban carbon budget which is critically important as 20-30% of urban landscapes are dedicated to lawns. Study objectives include quantifying/comparing total/seasonal biogenic CO2 efflux from soil respiration between lawns and forest (Cub Hill, Maryland). Hourly field measurements of net CO2 exchange from lawns and forest soils were collected using an automated soil CO2 efflux system beginning January 2015-June 2017. Data analysis utilized mixed-effects model (analogous to ANOVA with repeated measurements) comparing soil respiration between lawn and forests across seasons. Total soil respiration rates differed significantly (F = 7948, p = 0); mean soil CO2 efflux 1.92 + 0.02 (forest) and 2.67 + 0.03 (lawn) Ámol CO2 m-2 s-1. Analysis of seasons suggests greatest difference in soil respiration occurred during summer: mean soil CO2 efflux 3.77 + 0.03 (forest) and 4.95 + 0.03 Ámol CO2 m-2 s-1 (lawn) however, spring soil respiration rates were similar 2.37 + 0.04 and 2.55 + 0.03 Ámol CO2 m-2 s-1. Our finding suggests that conversation of forest to lawn results in greater CO2 efflux. However, during spring the combination of moderate soil temperatures coupled with increasing photosynthetic activity in lawns results in negative CO2 rates, suggesting the dynamic potential of lawns to serve as carbon sink and source.