Recent and Long‐Term Organic Soil Accretion and Nutrient Accumulation in the Everglades

Abstract Organic soil accretion and nutrient accumulation were measured in the northern, central, and southern Everglades to evaluate the effects of anthropogenic nutrient and hydroperiod alterations on organic C and nutrient storage during the past century. Six soil cores (euic, hyperthermic Typic Medisaprists) were collected from nutrient‐enriched (Water Conservation Area WCA 2A) and unenriched locations. Soil depth increments were analyzed for radionuclides ( 137 Cs, 210 Pb, 14 C), bulk density, and nutrients (C, N, P, S) to estimate recent (30‐yr) and long‐term (100‐yr) organic soil accretion and nutrient accumulation. Since WCA 2A was completely impounded in the early 1960s, organic soil accretion in northern WCA 2A (5.8–6.7 mm yr −1 ) increased by three to five times compared with before 1960 (1.9 mm yr −1 ) or with unenriched areas within and outside of WCA 2A (1.4–1.6 mm yr −1 ). Nutrient accumulation in the enriched area of WCA 2A since 1960 was two (184–223 g C m −2 yr −1 , 13.6–16.6 g N m −2 yr −1 ) to eight (0.40–0.46 g P m −2 yr −1 ) times higher than before 1960 (110 g C m −2 yr −1 , 6.6 g N m −2 yr −1 , 0.06 g P m −2 yr −1 ) or in unenriched areas (65–90 g C m −2 yr −1 , 4.7–6.4 g N m −2 yr −1 , 0.06 g P m −2 yr −1 ). Unenriched areas of the Everglades possess some of the lowest rates of P accumulation of peatlands in North America. Successful restoration of the Everglades will have to include the elimination of anthropogenic nutrient loadings to limit the P enrichment zone from expanding into existing unenriched interior areas and areas downstream of WCA 2A.