| Decomposition of 51 semidesert species from wide-ranging phylogeny is faster in standing and sand-buried than in surface leaf litters: implications for carbon and nutrient dynamics
Guofang Liu, William K. Cornwell, Xu Pan, Duo Ye, Fenghong Liu, Zhenying Huang, Ming Dong, and Johannes H. C. Cornelissen
由于光化学和物理降解,旱区环境中分解速率高于基于模型的预期值。然而，对立枯和沙埋凋落物（较地表凋落物）的碳和营养循环的认识相对不足。采集了51种凋落物材料，在地表、沙埋和模拟立枯三种条件进行原位的凋落物分解实验。结果表明，沙埋凋落物分解和模拟立枯均高于地表凋落物，而且这种格局不依赖于分解时间、谱系功能组或生长型。凋落物位置和分解时间显著地影响凋落物养分动态。沙埋和模拟立枯凋落物的氮和磷损失快于地表凋落物。对于分解6个月的凋落物，N损失慢于P损失，然而对于分解12个月的凋落物，则N损失快于P损失。这一研究表明，模拟立枯和沙埋的凋落物的较大干物质和营养损失可以作为解释旱区生态系统为何具有超过预期的高碳和营养循环。
Abstract
Background and Aims Higher than expected litter decomposition rates have been observed in dry, sunny environments due to photochemical or physical degradation. However, our understanding of carbon and nutrient fluxes of standing and buried litters compared to surface litter in such areas is still scarce.
Methods We sampled leaf litters from 51 species in a semiarid dune ecosystem and incubated them in three positions: surface, sand-buried and simulated standing.
Results Decomposition was much faster in buried litter and somewhat faster in simulated standing litter than in surface litter. This pattern was independent of the incubation period, phylogenetic group or growth form. Litter position and incubation period significantly impacted litter nutrient dynamics. The nitrogen (N) and phosphorus (P) losses were faster in buried and simulated standing litters than in surface litter. The N loss was slower than P loss in 6-month decomposed litter but the former was relatively faster than the latter in the second phase up to 12 months of incubation.
Conclusions our study shows that substantial mass and nutrient losses in simulated standing and buried litters can be a candidate explanation why drylands have higher carbon and nutrient fluxes than expected based on surface litter decomposition data alone.
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