Long‑term nitrogen addition consistently decreased litter
decomposition rates in an alpine grassland
作 者：Yuan Su · Jiajia Le · Wenxuan Han · Changhui Wang · Kaihui Li · Xuejun Liu
期 刊：Plant Soil
出版年份：2022
Abstract：
Aims
Litter decomposition is a crucial component of nutrient recycling. Short-term nitrogen (N) deposition has been shown to infuence litter decomposition in temperate steppe with signifcant variability due to diferences in atmospheric N deposition, species identity, and experimental duration. Therefore, the efect of N addition, especially long-term, on litter decomposition in alpine grassland still needs further investigation.
Methods
To address these knowledge gaps, we examined the infuence of long-term N addition on
litter decomposition, taking advantage of a feld experiment with fve N addition levels (0, 10, 30, 90,
and 150 kg N ha−1 yr−1) with a meta-analysis, which has been running for 11 years in an alpine grassland, Northwest China.
Results
Long-term N addition consistently decreased litter decomposition rates, and N negative efect became stronger with the increasing N addition rates. Reduced litter decomposition rates were related to lower soil enzymes activities. Litter decomposition rates were strongly correlated with litter quality, but weakly correlated with soil quality, but which suggested that litter quality and soil quality played important role in regulating litter decomposition. Furthermore, a regional meta-analysis revealed that N addition accelerated litter decomposition when all data were averaged. Although N addition indirectly increased litter decomposition, it had no direct efect on decomposition. However, the
direction and degree of the direct efect of N on litter decomposition were regulated by N addition rate, experimental duration and form of N fertilizer.
Conclusions
Overall, these results demonstrated that long-term N addition decreased litter decomposition and N negative efect increased over time.
Conclusions：
This study examined the impact of N addition on litter decomposition rate by combining feld experi
mental observations with regional meta-analysis. The results indicated that long-term N addition consistently decreased litter decomposition, and the N negative efect became stronger with the increasing N addition rates. Among several factors, initial litter quality and soil enzymes activities were notably crucial to the regulation of litter decomposition rate in response to long-term N addition, with initial litter quality being a more important determinant. The meta-analysis results showed short-term N addition had a nonsignifcant positive efect on litter decomposition, whereas long-term N addition inhibited litter decomposition. The efects of N addition on litter decomposition depended on the form of N fertilizer, experimental duration, and N addition rate. Overall, our results demonstrated that long-term N addition consistently slowed litter decomposition, with the N negative efect on litter decomposition increasing with the experimental duration. This meant that long-term N addition contributes to nutrients retained in litter and would weaken litter-mediated utrient cycling.
全文链接：doi.org/10.1007/s11104-022-05537-8
