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The response of plant species to a full-factorial experimental manipulation of soil pH and soil N in a Minnesota old field is compared to patterns observed in a chronosequence of old fields. Agropyron repens reached its greatest relative abundance in low pH but high N treatments. Schizachyrium scoparium was less affected by N, but was most abundant at low pH. Poa pratensis had its greatest relative abundance in high N and high pH treatments. Total biomass and species richness were also influenced by the treatments. Thus, the common plant species were differentiated in their responses to pH and N manipulations. However, these pH and N responses did not explain the patterns observed in the old field chronosequence unless the differential colonization abilities of the species and the relationships between soil pH, soil N and successional age were considered. |
