Satellite-based vegetation condition and phenology, and snow cover extent monitoring protocol for the Northern and Southern Colorado Plateau Networks

Thoma; Norris, Jodi; Lauck, Paul

This document describes the rationale and methods for monitoring land surface phenology and snow cover extent in the park units of the Northern and Southern Colorado Plateau Inventory and Monitoring Networks of the National Park Service. Phenology refers to the timing of annual biological events and is an indicator of vegetation response to a suite of environmental variables, most notably climate. Vegetation condition also changes in response to environmental variables, such as land management, disturbance, invasive species and vegetation assemblage. Individual plant responses cumulatively scale-up resulting in spatial and temporal landscape patterns that are detectable using satellite remote sensing techniques. Vegetation phenology and condition have been identified as core vital signs for long term monitoring in the Northern and Southern Colorado Plateau Networks (CPNs). Because vegetation condition and phenological responses are often interrelated, it can be beneficial to measure the two simultaneously. The CPNs have chosen to monitor phenology and vegetation condition by using remote sensing to measure vegetation greenness, as expressed by the Normalized Difference Vegeta-tion Index (NDVI). Vegetation provides the foundation for ecosystems, and remote sensing methods have been developed to measure greenness using satellites with sensors designed for this purpose. In addition to measuring seasonal pulses of vegetation greenup, the same satellite sensors provide measurements of the intensity of greenness. The timing, intensity and duration of greenness provide important information about changes in vegetation condi-tion and shifts in phenology. Snow cover can be used to understand the relationship between climate and the associated timing and intensity of spring greenup. The same satellite sensors that measure vegetation greenness can also measure the presence or absence of snow cover. Monitoring the vari-ability and trends in the timing and intensity of vegetation phenology, as well as snow cover extent may provide early indicators of climate change impacts that represent increased stress or vulnerability for plants and animals, or may presage gradual or sudden vegetation commu-nity shifts. The process described in this protocol not only provides information on vegetation phenol-ogy and the link with climate and snow cover extent, it also links climate with landscape vegetation condition, and other NPS vital signs. Many of the changes we anticipate in other NPS vital signs, such as upland bird populations, upland vegetation condition, aquatic mac-roinvertebrates, and riparian systems, are likely to be associated with changes in the timing, intensity, and duration of greenness and the timing, extent, and duration of snow cover. This protocol is divided into a narrative and a series of Standard Operating Procedures (SOPs). The narrative describes the history, advantages, and limitations of using remote sens-ing and specifically MODIS data to measure phenology. It then outlines the approaches that the CPNs will use to monitor phenology. Because of changing technology and data availabil-ity, we anticipate that the networks’ methods will change as well.

Satellite-based vegetation condition and phenology, and snow cover extent monitoring protocol for the Northern and Southern Colorado Plateau Networks

Series

See also

Collections