Zhao Hong-Mei, Yang Wei-Jun, Cheng Jun-Hui, Huang Gang, Hu Yu-Tong, Li Cong-Juan, Sheng Jian-Dong
Xinjiang Key Laboratory of Soil and Plant Ecological Processes, College of Resources and Environment Xinjiang Agricultural University Urumqi China.
College of Agronomy Xinjiang Agricultural University Urumqi China.
Ecol Evol. 2023 Aug 7;13(8):e10377. doi: 10.1002/ece3.10377. eCollection 2023 Aug.
Changes in nitrogen (N) deposition and litter mixtures have been shown to influence ecosystem processes such as litter decomposition. However, the interactive effects of litter mixing and N-deposition on decomposition process in desert regions remain poorly identified. We assessed the simultaneous effects of both N addition and litter mixture on mass loss in a litterbag decomposition experiment using six native plants in single-species samples with diverse quality and 14-species combinations in the Gurbantunggut Desert under two N addition treatments (control and N addition). The N addition had no significant effect on decomposition rate of single-species litter (expect ), whereas litter mass loss and decomposition rate differed significantly among species, with variations positively correlated with initial phosphorus concentration and negatively correlated with initial lignin concentration. After 18 months, the average mass loss across litter mixtures did not overall differ from those predicted from single species either in control or N addition treatments, that is, mixing of different species had no non-additive effects on decomposition. The N addition, however, did modify the direction of mixture effects and interacted with incubation time. Added N transformed synergistic effects of litter mixtures to antagonistic effects on mass loss after 1 month of decomposition, while transforming neutral effects of litter mixture to synergistic effects after 6 months of decomposition. Our results demonstrated that initial chemical properties played an important role in litter decomposition, while no effects of litter mixture on decomposition process in this desert region. The N addition altered the litter mixture effects on mass loss with incubation time, implying that increased N deposition in the future may have profound effects on carbon turnover to a greater extent than previously thought in desert ecosystems.
氮（N）沉降和凋落物混合的变化已被证明会影响诸如凋落物分解等生态系统过程。然而，在沙漠地区，凋落物混合和氮沉降对分解过程的交互作用仍鲜为人知。我们在古尔班通古特沙漠进行了一项凋落物袋分解实验，使用了六种质量各异的单一物种样本以及14种物种组合，在两种氮添加处理（对照和添加氮）下，评估了氮添加和凋落物混合对质量损失的同时影响。氮添加对单一物种凋落物的分解速率没有显著影响（预期），而凋落物质量损失和分解速率在不同物种间存在显著差异，其变化与初始磷浓度呈正相关，与初始木质素浓度呈负相关。18个月后，对照处理和氮添加处理中，凋落物混合物的平均质量损失总体上与单一物种预测的质量损失没有差异，也就是说，不同物种的混合对分解没有非加性影响。然而，氮添加确实改变了混合物效应的方向，并与培养时间相互作用。添加氮在分解1个月后将凋落物混合物对质量损失的协同效应转变为拮抗效应，而在分解6个月后将凋落物混合物的中性效应转变为协同效应。我们的结果表明，初始化学性质在凋落物分解中起重要作用，而在该沙漠地区凋落物混合对分解过程没有影响。氮添加随着培养时间改变了凋落物混合物对质量损失的影响，这意味着未来氮沉降增加可能比之前认为的在沙漠生态系统中更大程度地对碳周转产生深远影响。
