Higher relative performance at low soil nitrogen and moisture predicts field distribution of nitrogen-fixing plants

作者：Monks Adrian^*; Cieraad Ellen; Burrows Larry; Walker Susan

来源：Plant and Soil, 2012, 359(1-2): 363-374.

DOI：10.1007/s11104-012-1170-2

• Fabaceae
• Nitrogen fixation
• Nutrient availability
• Phosphorus
• Relative growth rate
• Spatial modelling

Symbiotic associations between vascular plants and nitrogen-fixing bacteria are expected to be costly except when N availability is low. We tested the prediction that in low-N soils in dry climates, plants with nitrogen-fixing symbioses (N-fixing species) have higher growth rates, and occur relatively more frequently, than non-fixing species,
In a pot experiment, we measured the growth and survival of 6 N-fixing and 8 non-fixing species across nitrogen and moisture gradients. Using plot survey data from the South Island, New Zealand, we then modelled the relative occurrence of N-fixing species using derived measures of temperature, soil N and moisture.
Non-fixing species had higher relative growth rates than N-fixing species except when both total N and soil moisture were low. Low soil moisture increased the root:shoot ratio in N-fixing species more than twice that observed in non-fixing species. Soil moisture had a strong effect on mortality, which was slightly lower for N-fixing species. Survey data showed that a higher proportion of N-fixing species were present at cool, dry sites with low levels of soil N.
In temperate climates, with geologically young landscapes, the influences of soil N and water on N availability are key factors determining the relative success of N-fixing and non-fixing species.

• 出版日期2012-10