Despite the high relevance of communities dominated by lichens, mosses and cyanobacteria living on the soil surface (biocrusts) for ecosystem functioning in drylands, no study to date has investigated the decomposition of biocrust-forming lichen litter in situ. Thus, we do not know whether the drivers of its decomposition are similar to those for plant litter (for example, importance of abiotic degradation through UV radiation), the magnitude of lichen decomposition rates and whether they will be affected by ongoing climate change. Here we report the results from a litter decomposition experiment carried out with two biocrust-forming lichens (Diploschistes diacapsis and Cladonia convoluta) that differ in litter chemical quality (C:N ratio) in central Spain. We evaluated how lichen decomposition was affected by warming, rainfall exclusion and their combination. We also manipulated the incidence of UV radiation using mesh material that blocked 10% or 90% of incoming UV radiation. Our results indicate that lichens decompose as fast as some plants typical of the study area (k ~ 0.3 y⁻¹). We observed differences among the species studied in line with what is expected according to their chemical composition. Warming increased decomposition rates of both lichen species by 28% and mediated the effects of photodegradation. Although UV exposure accelerated the decomposition of D. diacapsis, it slowed that of C. convoluta. Our results indicate that biocrust-forming lichens can decompose in the field at a rate similar to that of vascular plants and that this process will be affected by warming. The findings presented emphasize the need of considering biocrusts and the decomposition of their tissues when honing ecosystem models aiming to forecast carbon cycling responses to climate change in drylands.

尽管生活在土壤表面上的地衣，苔藓和蓝细菌占主导地位的社区与旱地中的生态系统功能密切相关，但迄今为止尚无研究调查原位形成生物结皮的地衣垃圾的分解。因此，我们不知道其分解的驱动力是否类似于植物凋落物的驱动力（例如，通过紫外线辐射进行非生物降解的重要性），地衣分解速率的大小以及它们是否会受到持续的气候变化的影响。在这里，我们报告了使用两个形成生物结皮的地衣（Diploschistes diacapsis和Cladonia convoluta）进行的凋落物分解实验的结果）在西班牙中部地区的垃圾化学质量（C：N比）不同。我们评估了地衣分解如何受变暖，降雨排除及其组合的影响。我们还使用可阻挡10％或90％传入UV辐射的网状材料来控制UV辐射的发生率。我们的研究结果表明，地衣分解快一些植物典型研究区域（ķ 〜0.3Ÿ ^-1）。我们观察到了所研究物种之间的差异，这与根据其化学成分所期望的相符。变暖将两种地衣物种的分解率提高了28％，并介导了光降解的作用。尽管紫外线暴露加速了D. diacapsis的分解，但减缓了卷曲藻的分解。。我们的结果表明，形成生物结皮的地衣可以在田间以类似于维管植物的速率分解，而且这一过程将受到变暖的影响。提出的研究结果强调，在珩磨旨在预测干旱地区气候变化的碳循环响应的生态系统模型时，需要考虑生物结皮及其组织的分解。