Carbon Sequestration under Warm Season Turfgrasses in Home Lawns

摘要

Turfgrass cover in the U.S. is expanding because of increasing urbanization and the addition of approximately 675,000 ha of residential property every year. Despite its large-scale presence in the urban ecosystem, the role of turfgrasses in carbon (C) cycling in home lawns in southeastern U.S. soils has not been documented, and studies with warm-season turf grasses are lacking. The objective of this study was to estimate carbon (C) sequestration in soil as affected by turfgrass species, including: bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy), centipede grass (Erecholmoa ophroides (Munroe) Hack.), and zoysiagrass (Zoysia spp.). The study was initiated in the winter of 2012 and conducted for two years on a loamy sand (fine-loamy, kaolinitic, thermic Typic Kanhapludult) soil. Eighteen lawns were sampled twice per year: six lawns of each grass species, with the harvested grasses separated into stems, above ground biomass (verdure) + thatch, and belowground roots. Soil samples (0 - 5, 5 - 10, and 10 - 20 cm) were also collected. Total C concentration was determined on finely ground-dried samples by combustion. Turfgrass species, season and years of sampling were all significantly (P ≤ 0.05) affected by C sequestration. Zoysiagrass had the highest mean levels of sequestered C, with a value of 5.54 ± 0.21, compared to 2.09 ± 0.11 and 4.23 ± 0.14 Mg·ha-1·yr-1 under bermudagrass and centipedegrass at the end of the study, respectively. This work indicates that turfgrass home lawns may be an important contribution to the global carbon sequestration level.