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Introduction to the USA-NPN Indicator Observation ProgramPhenology, which is derived from the Greek word phaino meaning to show or to appear, is the study of periodic plant and animal life cycle events that are influenced by environmental changes, especially seasonal variations in temperature and precipitation driven by weather and climate. Sprouting and flowering of plants in the spring, leaf color changes of plants in the fall, bird migration, insect hatches, and animal hibernation are all examples of phenological events. Plants are special, highly sensitive weather instruments that integrate the combined effect of weather factors such as temperature, rainfall, humidity, wind, and sunshine in their growth response. They can be observed year after year and dates recorded when certain growth stages, such as opening of leaf buds or appearance of first flowers occur. For over 50 years cooperators in the United States and Canada have assisted phenological researchers by reporting event dates for lilac and honeysuckle. Cloned plants (genetically identical individuals) have been employed to help minimize response variations between locations. Most recently in eastern North America, three indicator species, Syringa chinensis 'Red Rothomagensis' (lilac), Lonicera tatarica 'Arnold Red' (honeysuckle), and Lonicera korolkowii 'Zabeli' have been observed. Lilacs were used in the original study in the western United States (Caprio 1966), and honeysuckles were later added because they are adapted to a larger geographical range than the lilac. These plants were also selected because of their well-defined phenological events, cold hardiness, and resistance to heat and drought. Lilacs are not invasive, and the cloned Syringa chinensis 'Red Rothomagensis' lilacs are particularly well-suited as non-invasive scientific instruments since they are sterile and do not produce seeds. Due to their invasive nature, honeysuckles have not been distributed to observers since 1987, nor does USA-NPN actively support their distribution. USA-NPN honeysuckle observation support on these pages is directed toward legacy plants that began to grow at their present locations prior to 1987. Initially these studies were aimed at agricultural applications. For example, indicator phenology can be related to the growth of crops and insects in an attempt to predict crop yields, bloom dates (for more efficient management, Hopp 1978; Schultz 1982; Stetson 1982), and insect and disease infestations (for more economical and efficient control, Pendersen and Eckenrode 1981). Recently, phenology has been identified as a crucial contributor to global change research (Schwartz 1994,1998; Schwartz et al. 2006). Understanding the interaction between the atmosphere (weather and climate) and the biosphere (living organisms) is a necessary part of efforts to improve models of Earth's physical systems and monitor the impact of global climate change. Observations of cloned plants (such as the lilac) over large geographical regions serve as a vital link between satellite measurements and native plant phenology across regions and in local areas. Just as continuous and widely distributed weather observations have led to increased knowledge of atmospheric phenomena, so too will these phenological observations contribute to an active understanding of biospheric functions. Your yearly observations are an important part of the USA National Phenological Network (USA-NPN) and Global Phenological Monitoring (GPM) efforts. The instructions and information provided on these web pages for lilac and honeysuckle observations are essentially the same as those presented in a previous publication (Dubé et al. 1984). AcknowledgmentI wish to thank Joseph Caprio, Pierre Dubé, Charles Holetich, William Kennard, Helmut Lieth, Leonard Perry, Forest Stearns, Morrie Vittum, Robert Wakefield, and all the original researchers involved in regional phenology projects throughout the United States and Canada. Their foresight in establishing these phenological observation programs will provide an abundant harvest of knowledge to this and future generations. ReferencesCaprio, J. M. 1966. Patterns of plant development in the Western United States. Montana Agricultural Experiment Station Bulletin 607, Montana State University, Bozeman. Dubé, P. A., L. P. Perry, and M. T. Vittum. 1984. Instructions for phenological observations: Lilac and honeysuckle. Vermont Agricultural Experiment Station Bulletin 692, University of Vermont, Burlington. Hopp, R. J. (ed.). 1978. Phenology: an aid to agricultural technology. Vermont Agricultural Experiment Station Bulletin 684, University of Vermont, Burlington. Penderson, L. H., and C. J. Eckenrode. 1981. Predicting cabbage maggot flights in New York using common wild plants. New York's Food and Life Sciences Bulletin 87, New York State Agricultural Experiment Station, Geneva. Schultz, W., Jr. 1982. Plant a living garden calendar. Organic Gardening 29(4): 36-39. Schwartz, M. D. 1998. Green-wave phenology. Nature 394: 839-840. Schwartz, M. D. 1994. Monitoring Global Change with Phenology: The Case of the Spring Green Wave. International Journal of Biometeorology 38(1): 18-22. Schwartz, M. D., R. Ahas, and A. Aasa. 2006. Onset of Spring Starting Earlier Across the Northern Hemisphere. Global Change Biology 12(2): 343-351. Stetson, F. 1982. Lilacs know what day it is. Vermont Life 37(Spring): 59-61. |
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