National Park Service

Northeast Temperate Network (NETN)

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Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate. Examples include the date of emergence of leaves and flowers, the first flight of butterflies and the first appearance of migratory birds, the date of leaf coloring and fall in deciduous trees, the dates of egg-laying of birds and amphibia, or the timing of the developmental cycles of temperate-zone honey bee colonies. In the scientific literature on ecology, the term is used more generally to indicate the time frame for any seasonal biological phenomena, including the dates of last appearance (e.g., the seasonal phenology of a species may be from April through September). Because many such phenomena are very sensitive to small variations in climate, especially to temperature, phenological records can be a useful proxy for temperature in historical climatology, especially in the study of climate change and global warming. For example, viticultural records of grape harvests in Europe have been used to reconstruct a record of summer growing season temperatures going back more than 500 years. In addition to providing a longer historical baseline than instrumental measurements, phenological observations also provide high temporal resolution of ongoing changes related to global warming.

Importance & Issues

jefferson salamanderBiotic responses to climate change will likely be one of the most important conservation issues in the coming decades. By establishing baselines of phenological indictors in the NETN parks, it should be possible to document biotic responses to climate change. By monitoring phenological indicators in addition to climate variables, NETN would gain insight into the early impacts of climate change upon functioning ecosystems, including how different species may respond differently to climate change and how these differences may alter ecological relationships and perhaps ecosystem function. Although current funds will limit implementation of a phenology vital sign, we will build on the planned phenology project for the Appalachian Trail, and we hope to implement a rapid assay approach that can incorporate significant contributions from citizen volunteers. Implementing the phenology vital sign would draw upon existing protocols and standards of the European phenology network, the GLOBE program, and the Long-Term Ecological Research (LTER) program.

Monitoring Objectives

  • Establish long-term transects along elevational and altitudinal gradients of the Appalachian Trail and across selected NETN parks;
  • Monitor long-term trends in phenology of selected focal taxa and habitats, particularly focusing on populations occurring near the edge of species' ranges;
  • Monitor long-term trends in phenology of key invasive exotic species likely to benefit from climate change;
  • Compare and contrast current measurements to historical records and modeling efforts, in order to assess the magnitude of phenological change.


Establish baseline for and monitor trends for the following dates: leaf-out; flowering; bird arrival; butterfly and insect emergence; invasive plant emergence.

Ongoing Programs

Northeast Regional Migration Monitoring Network

Bringing together a diverse group of scientists from the National Park Service, US Fish & Wildlife Service, the University of Maine, and Acadia University, the Northeast Regional Migration Monitoring Network is using a multidisciplinary approach to determine migration patterns along the Gulf’s islands and coastal areas. As climate continues to change and plans for near-shore and terrestrial based wind development progress, it is critical to better understand the needs of migrating birds to inform responsible, landscape based resource management.

By using a variety of sampling methods, Network scientists are able to paint a more detailed
picture of bird migration along Maine’s coastal areas and beyond, details that might be missed
if only one or two methods were utilized. For more information, see their website here:

Northeast Regional Migration Monitoring Network

Watch Citizen Scientist volunteers collect data on plants at Boston Harbor Islands below.

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Last Updated: December 30, 2016 Contact Webmaster