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THE EFFECTS OF ELEVATED CO 2 ON NUTRIENT DISTRIBUTION IN A FIRE‐ADAPTED SCRUB OAK FOREST
Author(s) -
Johnson D. W.,
Hungate B. A.,
Dijkstra P.,
Hymus G.,
Hinkle C. R.,
Stiling P.,
Drake B. G.
Publication year - 2003
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/02-5139
Subject(s) - nutrient , chemistry , soil water , ecosystem , zoology , carbon dioxide , vegetation (pathology) , potassium , phosphorus , nitrogen , environmental chemistry , cation exchange capacity , ecology , agronomy , environmental science , soil science , biology , medicine , organic chemistry , pathology
Elevated carbon dioxide (CO 2 ) caused greater accumulation of carbon (C) and nutrients in both vegetation and O horizons over a 5‐yr sampling period in a scrub oak ecosystem in Florida. Elevated CO 2 had no effect on any measured soil property except extractable phosphorus (P), which was lower with elevated CO 2 after five years. Anion and cation exchange membranes showed lower available nitrogen (N) and zinc (Zn) with elevated CO 2 . Soils in both elevated and ambient CO 2 showed decreases in total C, N, sulfur (S), and cation exchange capacity, and increases in base saturation, exchangeable Ca 2+ , and Mg 2+ over the 5‐yr sampling period. We hypothesize that these soil changes were a delayed response to prescribed fire, which was applied to the site just before the initiation of the experiment. In the ambient CO 2 treatment, the increases in vegetation and O horizon C, N, and S were offset by the losses of soil total C, N, and S, resulting in no statistically significant net changes in ecosystem C, N, or S over time. In the elevated CO 2 treatment, the increases in vegetation and O horizon C content outweighed the losses in soil C, resulting in a statistically significant net increase in ecosystem C content. Nitrogen and S contents showed no statistically significant change over time in the elevated CO 2 treatment, however. Comparisons of vegetation contents and soil pools of potassium (K), calcium (Ca), and magnesium (Mg) suggest that a substantial proportion of these nutrients were taken up from either groundwater or deep soil horizons. This study demonstrates that changes in ecosystem C sequestration due elevated CO 2 or any other factor cannot be accurately assessed in the absence of data on changes in soils.