Abstract
1 Plant growth at high-latitude sites is usually strongly nutrient-limited. The increased nutrient availability predicted in response to global warming may affect internal plant nutrient cycling, including nutrient resorption from senescing leaves.
2 The effect of increased N supply (10 g N m(-2) year(-1)) on nitrogen and phosphorus resorption efficiency and proficiency in six sub-arctic bog species, belonging to four different growth-forms, was studied in northern Sweden.
3 We hypothesized that while increased N supply would not affect N or P resorption efficiency, it would lead to lower N resorption proficiency (higher N concentrations in leaf litter) and higher P resorption proficiency (lower P concentrations in leaf litter). We also investigated whether the basis on which resorption was expressed (leaf mass, leaf area or unit leaf) influenced the patterns observed.
4 Contrasting with our hypothesis, a general trend of decreased N resorption efficiency occurred in response to increased N supply, but the expected decrease in N resorption proficiency was seen in all species except Betula nana.
5 P resorption efficiency did not change in four species (B. nana, Empetrum hermaphroditum, Eriophorum vaginatum and Rubus chamaemorus) but it decreased in Andromeda polifolia, and increased in Vaccinium uliginosum. P resorption proficiency showed the expected increase in only two species (B. nana and V. uliginosum).
6 Apart from P resorption efficiency, the different calculation methods generally produced similar responses of resorption efficiency and proficiency to N supply.
7 Increased N supply at high-latitude sites clearly leads to more N being returned to the soil through leaf litter production. However, decomposition of such litter will probably become P-limited.
8 Considerable interspecific differences in nutrient resorption proficiency were found, indicating that long-term changes in vegetation composition need to be considered when evaluating plant-mediated effects on ecosystem nutrient cycling in response to increased nutrient supply.
| Original language | English |
|---|---|
| Pages (from-to) | 1060-1070 |
| Number of pages | 11 |
| Journal | Journal of ecology |
| Volume | 91 |
| Issue number | 6 |
| Publication status | Published - Dec 2003 |
Keywords
- global warming
- internal nutrient cycling
- leaf litter
- nutrient-limited growth
- SIMULATED ENVIRONMENTAL-CHANGE
- NUTRIENT RESORPTION
- LITTER DECOMPOSITION
- LEAF-LITTER
- RESPONSES
- PLANTS
- VEGETATION
- CLIMATE
- LEAVES
- GROWTH