Walking with Wildflowers

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Yarrow Flower


The Pacific Crest Trail (PCT) is a spectacular place to observe and record plant phenology. This trail spans from Mexico to Canada, and traverses the Sierra Nevada and Cascade Mountain ranges at elevations up to 13,159ft. Importantly, the PCT spans the physiological limits of many species, allowing researchers to directly test how climate impacts species across their ranges. Our volunteers survey the flowering status of several species of plants in predetermined sites while hiking the PCT. Because of the number of hikers that pass these sites on a daily basis, a continual stream of phenology observations is generated that would be impossible for researchers to generate on their own. A pilot project version of Walking with Wildflowers is funded by the National Science Foundation.

This pilot project involves setting up sites along the PCT in Yosemite, Crater Lake and North Cascades National Park, as well as starting to recruit hikers and record initial phenology data. This work was funded as part of study determining how a widespread species (Mimulus guttatus) has adapted to use photoperiod cues to time flowering across its species range and potential implications for adaptation to future climates. Walking with Wildflowers is a collaboration between scientists at several research institution and the USA National Phenology Network.


Changing climates have the ability to dramatically impact plant and wildlife populations. One of the most severe challenges that climate change poses to plant populations is altering growing season timing and duration. As winters shorten and become warmer while summers lengthen and become more arid, the optimal growing season for spring wildflowers moves earlier in the season and phenology – the timing of biological events – may be compromised.

These risks are particular concerning for subalpine and alpine wildflower communities, as these ecosystems will experience the greatest degree of change, including large year-to-year fluctuations in snow cover that can drastically alter the optimal timing for reproduction in plants. Long term studies at locations such as Rocky Mountain Biological Laboratory and Thoreau Woods have already demonstrated that some plants have been able to track changing climates over the last 50 years while other species have not.

Understanding which species are threatened depends foremost on documenting phenological patterns across time and space for floral communities to determine which species are able to acclimate or adapt. This can be a challenging goal for scientists with limited funding and time, as surveying phenology daily on the same plants in wilderness areas requires an extensive time commitment.

Walking with Wildflowers is designed to answer this challenge! We need your help to get the quality phenology data necessary to understand how plant populations respond to climate change!


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