Impact of different biobased mulches on the urban soil carbon dioxide flux in southern Louisiana.

摘要

The concerns over increasing concentration of carbon dioxide (CO 2) in the atmosphere have prompted forest researchers and managers to study the effects of various arboricultural and urban forest management practices on the carbon dynamics of intensely managed urban forest ecosystems. Soil respiration is a significant component of the carbon balance in an urban forest ecosystem, however, the impact of arboricultural practices such as mulching on the soil respiration remains poorly understood. This limits our ability to understand the carbon budget at the urban forest ecosystem level, thus making it uncertain to predict the impact of arboricultural practices such as mulching on soil respiration and its feedback.;The purpose of this study was to explore the relationship between the arboricultural management practice of mulching and carbon dynamics of intensely managed urban forest ecosystem. We determined the effects of five different mulch types on the establishment of urban trees for CO2 flux, plant nutrient uptake, shoot growth and selected soil chemical properties. We also observed the relationship between microbial organisms and soil respiration and its feedback. To accomplish this study we applied a complete randomized block design experiment and maintained it for two years. We applied five different biobased mulch types namely: Pine Bark (PB=A). Mixed Hardwoods (MH=B), Pine Needles (PN=C), No-Mulch (D), Mixed Oaks (MO=E), and Pine Bark + Pine Wood (PB+PW=F) on the soil surface in the study plots. We assessed the impact of the five urban tree-based mulch types on net canopy CO2 uptake of Quercus nuttallii saplings and their associated soil CO 2 fluxes. In the second year we analyzed the soil and nuttall oak leafs for nutrients (N, P, K, Ca, Mg, Mn, Fe, Cu, Zn, S, B, Al). Soil CO2 flux (imol CO2/m2/s) and tree canopy net CO2 uptake by tree saplings were not significantly impacted by pine bark and pine needle mulch types. Soil CO2 flux fluctuated significantly during the growing season under different mulch types. The largest increase in soil CO2 flux occurred during the month of May under the mixed hardwood mulch. Soil CO2 flux was highly correlated with time under all the mulch types. The results from nutrient analysis showed that there was no significant difference in the leaf nutrient content under different mulch types, however there was significant increment of soil nutrients under different mulch types.