Background and aims

Biocrusts are major contributors to dryland nutrient cycling by regulating C, N and P inputs and fluxes. However, our understanding about how the decomposition of biocrust constituents contributes to soil nutrient cycling in drylands is virtually unknown.

Methods

We conducted a microcosm experiment to: i) evaluate the litter decomposition dynamics of two common biocrust-forming species with contrasting tissue chemistry and growth form (the lichen Cladonia foliacea and the moss Syntrichia caninervis), and ii) their effects on several soil variables related to soil functioning.

Results

Cladonia litter decomposed gradually with time (92% total mass loss after 342 days), while Syntrichia litter decomposed much faster (92% total mass loss after 62 days, with no further losses until the end of the experiment at 342 days). We observed species-specific effects of their litter on dissolved organic N (DON) and NH4+ depending on collection time, which changed the effects of litter decomposition on DON and pH regardless of the biocrust species considered. Overall, biocrust litter had a positive effect on SOC, DON, \({\mathrm{NH}}_4^{+}\) and acid phosphatase activity.

Conclusions

Our experimental results show that decomposition of biocrust tissues plays an important role in soil nutrient cycling, indicating that this process impacts the fertility and functioning of dryland soils.

中文翻译：

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旱地形成生物结皮的地衣和苔藓的分解有助于土壤养分循环

背景和目标

通过调节 C、N 和 P 输入和通量，生物结皮是旱地养分循环的主要贡献者。然而，我们对生物结皮成分的分解如何促进旱地土壤养分循环的理解实际上是未知的。

方法

我们进行了一个缩影实验，以：i) 评估两种常见的生物结皮形成物种的凋落物分解动力学，这些物种具有不同的组织化学和生长形式（地衣Cladonia foliacea和苔藓Syntrichia caninervis），以及 ii) 它们对几个与土壤相关的变量的影响到土壤功能。

结果

Cladonia凋落物随时间逐渐分解（342 天后总质量损失 92%），而Syntrichia凋落物分解得更快（62 天后总质量损失 92%，直到 342 天实验结束前没有进一步损失）。我们观察到它们的凋落物对溶解的有机 N (DON) 和 NH4+ 的物种特异性影响取决于收集时间，这改变了凋落物分解对 DON 和 pH 值的影响，而与所考虑的生物结皮物种无关。总体而言，生物结皮垃圾对 SOC、DON、\({\mathrm{NH}}_4^{+}\) 和酸性磷酸酶活性有积极影响。

结论

我们的实验结果表明，生物结皮组织的分解在土壤养分循环中起着重要作用，表明这一过程会影响旱地土壤的肥力和功能。