Phenology
Phenology
Introduction
Phenology is the study of the timeframes during which natural events occur and their relation to climate. Examples include the dates of the blooming of leaves or flowers, return of migrating species such as butterflies and birds, melting of lake ice in spring, and development of fall colors of the leaves of deciduous trees.
The timing of such natural events is influenced by climate. Thus, phenology records can be useful in substantiating climate change, especially alterations in temperature over time. Phenology data indicate that global warming is altering local environments all over the world, in some cases leading to a decrease in the diversity of life in some regions.
Historical Background and Scientific Foundations
Humans have been aware of the seasonal changes in the natural environment for thousands of years. Phenology records date back to at least the eighth century AD. The origin of the word phenology is derived from the Greek word phainomai, meaningtoappearortocomeintoview.
In 1875, the British Meteorological Society began to compile phenology information on a nationwide scale. Data were collected each year until 1948. Annual observations re-commenced in 1998 through the UK Phenology Network. In the United States, the USA National Phenology Network was established in 2007.
Such careful tracking of the dates of a particular natural event can provide data that are useful in revealing climate change. An example is data that were kept about the appearance of oak leaves on an English estate. The records, first kept by the estate owner in 1736, have been maintained since. They reveal a long-term trend of earlier appearance of leaves in the spring, particularly from 1960 to 2007. The progressively earlier blooming of the oak trees coincides with temperature records in the region, substantiating the warming of the atmosphere that has occurred over the same period.
Phenology has progressed beyond simple observations. Currently, orbiting satellites record information at regular intervals on ocean temperatures, also of growing seasons via the infrared monitoring of vegetation. Phenology data on entire ecosystems can now be collected.
Impacts and Issues
Phenology can be a powerful means of probing climate change, as the observations can be taken by people who are not formally trained as scientists (who have been dubbed “citizen scientists” by the USA National Phenology Network). Thus, large numbers of people can be recruited to record, for example, the dates of leaf blooming in the spring.
The data obtained over time are useful in agriculture, monitoring of droughts, assessing the risks of forest fires in an approaching summer season, following the geographic expansion of unwanted pests, and even monitoring the spread of an infectious disease (in this sense, the discipline of epidemiology uses aspects of phenology).
WORDS TO KNOW
ECOLOGY: The branch of science dealing with the interrelationship of organisms and their environments.
SATELLITE IMAGING: Creating images of Earth from data collected by artificial satellites. Today, most satellite imaging consists of digital photographs collected by satellites and radioed to Earth stations. Other techniques include the collection of gravity measurements that are processed on Earth to yield imagery, such as the melting of the Greenland ice cap.
The effects of global warming on the environment have been verified by observations including the time of year when honeybees are actively engaged in obtaining pollen from flowers, the appearance of native wild-flowers, and the natural environment around Walden Pond in Massachusetts.
Of the nearly 600 species of plants observed by the philosopher and writer Henry David Thoreau (1817–1862) around Walden Pond in the 1850s, only 400 have been identified in annual surveys done by botanists from 2002 to 2007. The cause, according to the scientists involved in the survey, may be warming temperatures that have disrupted the pollination cycle of many species.
See Also Ice Core Research; Milankovitch Cycles; Temperature Record.
BIBLIOGRAPHY
Books
Diamond, Jared. Collapse: How Societies Choose to Fail or Succeed. New York: Penguin, 2006.
Periodicals
Chuine, I., P. Yiou, N. Viovy, et al. “Grape Ripening as a Past Climate Indicator.” Nature. 432 (2004): 289-290.
Nijhuis, Michelle. “Teaming up with Thoreau.” Smithsonian (October 2007).
Web Sites
“Buzzing About Climate Change.” National Aeronautics and Space Administration (NASA), September 7, 2007. <http://earthobservatory.nasa.gov/Study/Bees/> (accessed November 25, 2007).
phenology
1. The study of the periodicity of leafing, flowering, and fruiting in plants; these are generally triggered by periodicities in the climate.
2. The study of the impact of climate on the seasonal occurrence of flora and fauna (dates of flowering, migration, etc.) and of the periodically changing form of an organism, especially as this affects its relationship with its environment.