Abstract
Background and aims: Vegetation fire often raises levels of soil phosphorus (P) relative to those of nitrogen (N), while long-term fire exclusion is associated with accumulation of soil N and depletion of soil available P. Thus, high-frequency fire regimes might trigger N-limited plant growth in otherwise P-limited plant communities. Methods: We used soils from a long-term prescribed burning trial to grow Eucalyptus pilularis under several nutrient amendment conditions. We measured seedling growth, soil and plant chemistry, and root enzyme activities to assess nutrient status. Results: Biennially-burned (2yB) soils had higher labile P concentrations than long-unburned (NB) soils, and lower total and labile N:P ratios. This did not correspond to N-limited growth or stimulate seedling N demand. Seedlings grown with addition of N, P and micro-nutrients in combination (μMax treatment) attained 68% more biomass than unfertilised seedlings. Addition of P resulted in higher total biomass than addition of N, and similar biomass to the μMax treatment, suggesting partially P-limited growth. Plants grown in 2yB soils tended to be enriched with P, K, Ca and Mg compared to those grown in NB or 4yB soils. Conclusions: High-frequency prescribed burning depletes soil N relative to P, but this does not trigger a shift toward N-limited growth of E. pilularis seedlings. Instead, E. pilularis seedlings appear to grow under partial P-limitation which persists regardless of their soil’s fire history.
Original language | English |
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Pages (from-to) | 191-205 |
Number of pages | 15 |
Journal | Plant and Soil |
Volume | 432 |
Issue number | 1-2 |
DOIs | |
State | Published - Nov 1 2018 |
Keywords
- Ash deposition
- Chitinase
- Phosphatase
- Prescribed burning
- Stoichiometry