Effects of Nutrient Enrichment on the Producer Trophic Level of a Six-Year Old-Field Community
نویسنده
چکیده
The effects of nutrient enrichment (i.e., application of sewage sludge and fertilizer) on a 6-yearold-field community were investigated. Vegetation was harvested in eight 0.1-ha plots comprising three treatments. Three plots were treated five times annually (May-September) with sludge; three plots were treated with an equivalent nutrient subsidy of urea-phosphate fertilizer; and two plots were left as untreated controls. Nutrient-enriched plots, dominated by the annuals Ambrosia trifida, Ambrosia artemisiifolia, and Lactuca scariola, exhibited lower species richness values but greater evenness values than the controls, which were dominated by the perennials Solidago canadensis and Rubus frondosus. Primary productivity values (g • m^yr^^S.D.) for fertilizer, sludge, and control plots were 1737±304, 1384±222, and 1009±56, respectively. Fertilizer-treated plots exhibited significantly greater (P < 0.05) productivity than control plots. Changes in plant species composition, diversity, and productivity suggest that nutrient-enriched plots are representative of an earlier serai stage of old-field succession as compared to controls. We conclude that continuous nutrient enrichment of old-field communities retards secondary succession when application is initiated immediately following agricultural practice. OHIOJ. SCI. 86(1): 10-14, 1986
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