Extracting plant phenology metrics in a Great Basin watershed: methods and considerations for quantifying phenophases in a cold desert

Authors: Snyder, Keirith; WEHAN, BRYCE; FILIPPA, GIANLUCA - ENVIRONMENTAL PROTECTION AGENCY OF AOSTA VALLEY; HUNGINGTON, JUSTIN - DESERT RESEARCH INSTITUTE; STRINGHAM, TAMZEN - UNIVERSITY OF NEVADA; SNYDER, DEVON - UNIVERSITY OF NEVADA

Submitted to: Sensors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2016
Publication Date: 11/18/2016
Citation: Snyder, K.A., Wehan, B., Filippa, G., Hungington, J.L., Stringham, T.K., Snyder, D.K. 2016. Extracting plant phenology metrics in a Great Basin watershed: methods and considerations for quantifying phenophases in a cold desert. Sensors. doi: 10.3390/s16111948.

Interpretive Summary: Studies and observations of plant phenology have been critical to ecology, agricultural production, and understanding multi-trophic interactions. Land managers and producers have been assessing phenophases through field-based surveys for centuries to determine relationships with weather, climate, and proper management strategies. In the last several decades, remotely sensed data has provided various indices of plant vigor at large spatial scales that have provided invaluable information on vegetation cover. This study looks at using simple land-based cameras programmed to take multiple images in one day of common community types in rangelands of the Great Basin. We found these cameras were capable of assessing phenological changes in sagebrush steppe communites, pinyon and juniper woodlands, and wet and mesic meadows. The ability to monitor plant phenology with camera-based images fills spatial and temporal gaps in remotely sensed data and field based surveys, by taking fine-scale daily images, thus providing powerful new tools for land management.

Technical Abstract: Plant phenology is recognized as important for all trophic interactions. There has been a recent advent of phenology and camera networks worldwide. The established PhenoCam Network has sites in coterminous United States, including the western states. However, there is a paucity of published research from semi-arid regions. In this study we demonstrate the utility of camera-based repeat digital imagery and use of R statistical phenopix package to quantify plant phenology and phenophases in four plant communities in the semi-arid cold desert region of the Great Basin. We developed a new automated variable snow/night filter for removing ephemeral snow events, that allowed fitting of phenophases with a double logistic algorithm. We were able to detect low amplitude seasonal variation in pinyon and juniper canopies and sagebrush steppe, and characterize wet and mesic meadows in area-averaged analyses. We used individual pixel-based spatial analyses to disentangle sagebrush shrub canopies from interspace areas. The ability to monitor plant phenology with camera-based images fills spatial and temporal gaps in remotely sensed data and field based surveys, allowing species level relationships between environmental variables and phenology to be developed on a fine time scale thus providing powerful new tools for land management.