Reversal of Extreme Drought-Induced Plant Nitrogen and Phosphorus Imbalances in Grassland
摘要
The balances of nitrogen (N) and phosphorus (P) in plants are important for numerous fundamental ecological processes. These balances are vulnerable to global change drivers, including extreme drought, yet it remains largely unknown whether plant N:P imbalances are reversible. This issue is even more complex at the community level, where the recovery of community composition and its influence on N:P ratio pose significant challenges. We examined the responses of green and senesced leaf N:P ratios at both species and community levels to a 4-year extreme drought and their subsequent recovery over two years in a temperate steppe. Drought increased leaf N:P ratios of most dominant species and the dominance of grasses, which have higher N:P ratios than forbs, resulting in stronger leaf N:P imbalances at the community level. The increased community N:P ratios can recover within two years after drought cessation, largely due to the reduced soil N concentration caused by plant overgrowth during the post-drought period. Our results indicate that drought-induced N:P imbalances in plant community are reversible and highlight the role of community compositional changes in driving plant N:P stoichiometric responses to drought and recovery.