USA NPN National Phenology Network

Taking the Pulse of Our Planet

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Species & Protocols

This group is working to identify a list of species that USA-NPN will recommend as target species for monitoring, and with identifying or developing protocols suitable for using those species to monitoring important phenological events.

Criteria Flowers Criteria for selecting target species are varied, and justifications for selection are necessarily nuanced. Some obvious criteria include ease of identification and observation, sensitivity to different temperature and precipitation thresholds; overlap with species being measured by phenology networks in other countries; breadth of distribution in U.S.A.; ecological amplitude; local and regional dominance; functional, reproductive and dispersal characteristics; economic, social or conservation value; and importance for calibrating remote sensing products and detecting climate change/variability. Groups interested in large-scale process (e.g., biogeochemical cycling, primary productivity, disturbance ecology, ecohydrology, vegetation modeling, and ground-truthing of remote sensing) will naturally focus on widespread and dominant plant species. Conservation biologists studying alpine floras will want to target at risk plants or host plants for at-risk organisms, while phenology of non-native species is essential to most efforts to manage plant invasions via herbicides or biocontrol. At least initially, the list of target species is also constrained by specific interests and species distributions within participating networks and programs.


Focal Species

The Species and Protocols Group (S&P) applied a combination of desired criteria and applications to a comprehensive plant database ( and has developed a list of about 150 species, which will be vetted by participating networks and programs. The primary goal of this selection is to establish a baseline of phenological patterns for plants and animals across the nation, help monitor and detect phenological responses to climate change, immediately demonstrate the national scope of network, and engage the largest possible number of participants within a backbone network.


In developing protocols for phenological observations, the S&P group considered siting criteria. Monitoring sites should have convenient access, be secure through time, experience minimum disturbance, and have well defined metadata. For lilacs and other cloned indicator species, near proximity to a met station is mandatory. For native species, the location should be representative of the vegetation type in a larger area (~ 1ha for sites where remote sensing observations are also being obtained). Phenophases will be based on the general BBCH scale used by European Phenology Network or other available protocols, modified to accommodate target species. Ideally, there should be a small number of individuals evaluated per species for a given phenophase. The time commitment at each site should be less than 1 hour for observations, 3 times per week (for a sampling interval of 3 days maximum, spanning at least 5 days from the 1st to the 3rd observation), with <15 minutes of data for each observation day. The above should be conducted around the time of the relevant phenophases, and time commitments can be reduced in the well-defined "off-season." Protocols also are being developed in collaboration with the Remote Sensing Group to provide surface observations of community greenness on a relative scale.