Effect of traffic stress and planting density on biomass and carbon exchange in bermudagrass

Turfgrass often suffers from traffic stress, which reduces its biomass, including leaf wear and soil compaction. Although plant biomass is related to carbon balance over the canopy, the reduction in biomass due to traffic stress on turfgrass has not been discussed in terms of the carbon balance on turfgrass. Leaf wear can damage the photosynthetic rates of leaves and soil compaction can damage the respiration process of roots. Photosynthesis and respiration are important physiological properties, and the difference between them represents the total carbon gain over the turfgrass. This study conducted four levels of traffic experiments on bermudagrass grown in two levels of planting density, and investigated leaf and root biomass and carbon exchange, including photosynthesis and respiration. A decrease in leaf and root mass was found with the intensity of traffic stress. Photosynthetic rates per leaf mass did not change with the intensity of traffic stress but were 1.7 times higher in high planting density. On the other hand, respiration rates per plant mass decreased with the intensity of traffic stress and were 1.3 times higher in high planting density. When summarizing photosynthesis, respiration, and biomass, the total carbon balance in high-traffic intensity and low-planting density should be small. Therefore, the turfgrass population may degrade under such conditions. It can be concluded that the carbon balance over the turfgrass may serve as an indicator for detecting the effect of traffic stress and suggest management practices that take into account traffic stress and planting density, such as increasing planting density where traffic stress is high.