Interdisciplinary research has been identified as a critical means of addressing some of our planet's most urgent environmental problems. Yet relatively little is known about the processes and impacts of interdisciplinary approaches to environmental sciences. This study used citation analysis and ordinary least squares regression to investigate the relationship between an article's citation rate and its degree of interdisciplinarity in one area of environmental science; viz., forestry. Three types of interdisciplinarity were recognized: authorship, subject matter, and cited literature, and each was quantified using Brillouin's diversity index. Data consisted of more than 750 articles published in the journal Forest Science during the 10-year period 1985-1994. The results indicate that borrowing was the most influential method of interdisciplinary information transfer. Articles that drew information from a diverse set of journals were cited with greater frequency than articles having smaller or more narrowly focused bibliographies. This finding provides empirical evidence that interdisciplinary methods have made a measurable and positive impact on the forestry literature.