Abstract
Soils vary widely in mineral nutrient availability and physical characteristics, but the influence of this variability on plant responses to elevated CO2 remains poorly understood. As a first approximation of the effect of global soil variability on plant growth response to CO2, we evaluated the effect of CO2 on tall fescue (Festuca arundinacea) grown in soils representing 10 of the 12 global soil orders plus a high-fertility control. Plants were grown in small pots in continuously stirred reactor tanks in a greenhouse. Elevated CO2 (800 ppm) increased plant biomass in the high-fertility control and in two of the more fertile soils. Elevated CO2 had variable effects on foliar mineral concentration—nitrogen was not altered by elevated CO2, and phosphorus and potassium were only affected by CO2 in a small number of soils. While leaf photosynthesis was stimulated by elevated CO2 in six soils, canopy photosynthesis was not stimulated. Four principle components were identified; the first was associated with foliar minerals and soil clay, and the second with soil acidity and foliar manganese concentration. The third principle component was associated with gas exchange, and the fourth with plant biomass and soil minerals. Soils in which tall fescue did not respond to elevated CO2 account for 83% of global land area. These results show that variation in soil physical and chemical properties have important implications for plant responses to global change, and highlight the need to consider soil variability in models of vegetation response to global change.
Highlights
Substantial attention has been given to the effects of elevated CO2 concentration on plant growth and physiology (Körner, 2006), reflecting concern about the performance of both cultivated and wild plants in future climates characterized by elevated CO2 (IPCC, 2007a)
Of the soils used in this experiment, only INC2 did not support any germination of tall fescue
The remaining soils produced 50–80% less shoot biomass than control treatment (CTR), indicating significant differences among soils (Table 2). These differences were especially notable under elevated CO2, where biomass of CTR increased by about 60% (Figure 1A)
Summary
Substantial attention has been given to the effects of elevated CO2 concentration on plant growth and physiology (Körner, 2006), reflecting concern about the performance of both cultivated and wild plants in future climates characterized by elevated CO2 (IPCC, 2007a). In contrast to research with crops and model plants, forestry and ecological research has considered the effects of elevated CO2 in natural soils without amendments or fertilizers. Such studies generally indicate multiple and complex limitations, mostly of edaphic origin, that trees face under elevated CO2 (Bucher-Wallin et al, 2000; Bassirirad et al, 2001; Egli et al, 2001; Poorter and Perez-Soba, 2001; Spinnler et al, 2002)
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