Nursery Production Method Performance Evaluation Assessed With The Normalized Difference Vegetation Index Derived From An Unmanned Aircraft System Mounted Single-Imager Sensor

Abstract

Trees provide many benefits to urban areas including enhanced human health, pollution mitigation, and reductions in residential energy consumption. The goal of urban forest managers is to develop mature trees with large crowns to maximize these benefits. Urban trees have the highest mortality rate during the initial years post planting, known as the establishment period. In an era of planting trees to reach quotas, the looming fact is many perish during establishment limiting goal achievement. Nursery production methods (NPM) are a controllable factor in practice that may have an impact on establishment success. In this study, urban trees planted in situ from four common NPM’s (balled and burlapped, smooth plastic containers, spring planted bareroot, and gravelbed bareroot) were monitored for three years post planting using the normalized difference vegetation index (NDVI). This data was derived from high-resolution imagery collected with an unmanned aircraft system (UAS). First, the single-imager multispectral sensor selected for this project was evaluated for effectiveness in determining tree health. This was done in a controlled growth chamber environment. Results showed the single-imager sensor derived NDVI values were effective indicators of tree stress within species groups. Second, a novel technique to isolate tree crowns for spectral data analysis with UAS derived imagery was utilized to compare the health of newly planted trees in situ from the four NPM’s. Analysis of the effect NPM’s had on tree health during the establishment period showed minimal differences between the study groups thus providing evidence that each is a viable option for practitioners in urban areas.