Assessing the effects of water conservation on the aesthetic value, carbon sequestration, and potential irrigation-induced cooling benefits of Buffalograss and St. Augustine turfgrass species in inland southern California

Optimizing irrigation water use efficiency by applying the right amount of water at the right time based on plant needs could enhance water conservation. Though this requires investigating how different plant species respond to water quantity and watering frequencies, as each specie responds differently. In arid places, drought-tolerant plant species are suitable as they can provide ecosystem services with less water. Additionally, restricting irrigation is an emergency mitigation plan in severe drought conditions. However, although restricting irrigation help saves water, it might limit ecosystem functioning, especially in prolonged periods. Therefore, extensive and intensive research on the tradeoffs between urban water conservation and landscape ecosystem services is needed.
This study assesses plant response to various irrigation water amounts and watering frequencies in turfgrass ecosystems. Through a field trial experiment of two warm-season turfgrass species, we will apply six irrigation rates (80-, 70-, 60-, 50-, 40-, 30-% ETo) based on evaporation and transpiration, and two irrigation frequencies (three and six days a week). We will then monitor plant visual quality, Normalized Vegetation Index (NDVI), canopy temperatures, changes of water in the root zone, and carbon dynamics using a combination of handheld sensor instruments, an Unmanned Air Vehicle (UAV), and an automated Infrared Gas Analyzer (LI 8100A). The preliminary data shows strong evidence that irrigation rate affects NDVI, canopy temperature, andCO2 efflux (P-value < 0.05), but irrigation frequencies only affect CO2 efflux. Overall, the highest irrigation rate (80%ETo) had the highest average NDVI, CO2 efflux, and lowest canopy temperature, whereas the lowest irrigation rate (30%ETo) had the lowest average NDVI, and CO2 efflux, and highest average canopy temperature. There was also a general declining trend in NDVI over time and an increasing trend in canopy temperature and CO2 efflux.