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    This indicator estimates population trends of selected species as a surrogate measure of genetic diversity. Decreases in genetic diversity as populations decline, particularly if associated with small populations, contribute to increased risk of extinction. This indicator also provides an important measure of general biodiversity, as changes in species abundances are a more sensitive measure of environmental stress than species richness alone. Between 1966 and 2000, about 26 percent of bird species associated with U.S. forests increased and 27 percent decreased; for nearly half the species there was no strong evidence for an increasing or decreasing trend. Physiographic regions where more forest birds declined than increased were clustered along the coast and eastern third of the U.S. The majority of tree species (or species groups) tracked by the Forest Inventory and Analysis program increased by >50 percent in numbers of stems >12 inches in diameter between 1970 and 2002. State agency data indicate that populations of many big game species increased in the last 25 years, but forest-dependent small game species showed mixed trends. The paucity of population data for taxa other than bird and tree species points out the need to develop systematic strategies for monitoring population levels of other animal and plant taxa.

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    Sieg, Carolyn Hull; Flather, Curtis H.; Barstatis, Noah. 2003. Criterion 1: Conservation of biological diversity - Indicator 9: Population levels of representative species from diverse habitats monitored across their range. In: Darr, David R., coordinator. Data Report: A Supplement to the National Report on Sustainable Forests -- 2003. FS-766A. Washington, DC: USDA Forest Service, Research & Development. Online:


    forest bird population trends, trends in tree stem counts, big game population trends, small game population trends, sustainability indicators, sustainable forest management

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