Many Earth system models predict increasing atmospheric carbon dioxide (CO2) concentrations will enhance both terrestrial net primary productivity (NPP) and global terrestrial carbon (C) storage, slowing the pace of anthropogenic climate warming. When these predictions are adjusted for the availability of nutrients, however, terrestrial ecosystems are predicted to store far less C, potentially becoming net C sources. Overcoming potential nutrient constraints would require new nutrient inputs or an increase in recycling process rates. Multiple pathways of new N inputs exist, and some evidence suggests that future climate warming could support elevated rates of net N mineralization. However, P inputs to ecosystems are very low, and temperature effects on P mineralization remain poorly understood. Here, we incubated soils from major terrestrial biomes from 5 to 45°C at 10°C intervals for 14 days to test the effect of temperature on net soil P mineralization rates. We predicted that where phosphatase enzyme activities are not limited by the pool of organic P, rates of net P mineralization would increase with temperature, perhaps enhancing soil P supply.
Results/Conclusions
The effect of temperature on net N mineralization was inconsistent across biomes. By contrast, soil net P mineralization rates generally increased with temperature at all sites, but were only significant when incubation temperatures were at least 10°C greater than the mean annual temperature (MAT) of any particular site. The increase in mineralization with temperature was larger in soils with smaller pools of labile, inorganic P, suggesting that warming effects are stronger in soils with limited P supply. Overall, our results show that ecologically relevant increases in P mineralization may require temperature increases far in excess of those predicted as a result of anthropogenic climate warming. Thus, while terrestrial ecosystems may have some capacity to overcome potential nutrient constraints to NPP via accelerated nutrient recycling, our preliminary results suggest that climate change driven increases in nutrient mineralization insufficient to meet the future nutrient demands of NPP.