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Plant Phenology



  • Carl Roland
  • E Nicklen

Park Units:

Resource Brief

A defining characteristic of CAKN ecosystems is extreme seasonality: the presence of seasonal snow cover (currently) for ~8-9 months, and a compressed growing season of ~3-4 months. Seasonal snow cover defines the length of the growing season, is a major determinant of the annual water cycle, and greatly affects the reproduction and survival of animals. Within the snow-free season, the progression of vegetative development depends on climatic parameters including temperature, precipitation, and cloudiness (solar radiation). The benchmarks in the annual development of seasonal snow cover and the vegetation canopy in CAKN parks are: (1) snow-free date, (2) date of onset of greenness (“green-up” date), (3) date of maximum greenness, (4) date of senescence of greenness, and (5) snow-cover date. Annual variation in the timing of these events may have profound effects upon a wide variety of ecosystem processes, including net primary productivity, and survival rates and reproductive success for both plants and animals. We expect that an initial effect of climate change would be changes in the timing of these events. Changes in the distribution and abundance of the biota would likely follow any significant and directional changes in the timing of seasonal snow cover and plant growth and senescence. Detecting trends in landscape phenology was selected as a Vital Sign for CAKN because of the fundamental importance of vegetation productivity and snow cover to ecosystem structure and function. The Landscape Phenology Vital Sign will provide an annual measure of key ecosystem processes across the entire network landscape. This vital sign will play an integrative role with other vital signs (especially Vegetation Structure and Function, Climate and Snow Cover, Permafrost, Glaciers, Disturbance Processes: Fire, and all faunal vital signs).


Citation Year Type Access Holdings IRMA
Download RB_CAKN_VegAspenPhen_Oct12.pdf National Park Service, Central Alaska Network (CAKN). 2012. The phenology of flowering, leaf-out and senescence in aspen (Populus tremuloides) in the Central Alaska Network 2012 Resource Brief Public 1 Link to
Download AspenReport_Final_nrss.pdf Roland C and Nicklen EF. 2011. Aspen phenology monitoring in the Central Alaska Network of the National Park Service: Progress report 2010. Natural Resource Technical Report. NPS/CAKN/NRTR—2010/501. Naional Park Service, Natural Resource Stewardship and Science. Fort Collins, Colorado 2011 Published Report Public 1 Link to
Southwould A and Roland C. 2008. Phenology Database. National Park Service. Central Alaska Network; Inventory and Monitoring Program. Fairbanks, Alaska. (Restricted) 2008 Relational Database Restricted 1 Link to


Key words: alaska, greenness, green-up, phenology, productivity, senescence, snow-cover, snow-free date, timing

Subject Categories:

  • Ecological Framework: Air and Climate | Weather and Climate | Weather and Climate
  • Ecological Framework: Biological Integrity | Focal Species or Communities | Vegetation Complex
  • Ecological Framework: Geology and Soils | Soil Quality | Soil Function and Dynamics

View this project 'Plant Phenology Monitoring in the Central Alaska Network' on the IRMA Data Store | JSON | XML | Project reference last updated on 2017-11-16 12:40:29 by

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