Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Sci Rep. 2017 May 31;7(1):2573. doi: 10.1038/s41598-017-02812-y.
Biocrusts are model ecosystems of global change studies. However, light and non-rainfall water (NRW) were previously few considered. Different biocrust types further aggravated the inconsistence. So carbon-exchange of biocrusts (cyanobacteria crusts-AC1/AC2; cyanolichen crust-LC1; chlorolichen crust-LC2; moss crust-MC) utilizing NRW at various temperatures and light-intensities were determined under simulated and insitu mesocosm experiments. Carbon input of all biocrusts were negatively correlated with experimental temperature under all light-intensity with saturated water and stronger light with equivalent NRW, but positively correlated with temperature under weak light with equivalent NRW. LCPs and R/Pg of AC1 were lowest, followed in turn by AC2, LC2 and MC. Thus AC1 had most opportunities to use NRW, and 2.5 °C warming did cause significant changes of carbon exchange. Structural equation models further revealed that air-temperature was most important for carbon-exchange of ACs, but equally important as NRW for LC2 and MC; positive influence of warming on carbon-input in ACs was much stronger than the latter. Therefore, temperature effect on biocrust carbon-input depends on both moisture and light. Meanwhile, the role of NRW, transitional states between ACs, and obvious carbon-fixation differences between lichen crusts should be fully considered in the future study of biocrusts responding to climate change.
生物结皮是全球变化研究的模式生态系统。然而，先前很少考虑光和非降雨水（NRW）。不同的生物结皮类型进一步加剧了这种不一致性。因此，在模拟和原位中观实验下，利用不同温度和光照强度下的 NRW ，确定了生物结皮（蓝藻结皮-AC1/AC2；蓝藻地衣结皮-LC1；绿藻地衣结皮-LC2；苔藓结皮-MC）的碳交换。在所有光照强度和饱和水条件下，所有生物结皮的碳输入均与实验温度呈负相关，而在等量 NRW 和较弱光照条件下，与温度呈正相关。AC1 的 LCP 和 R/Pg 最低，其次是 AC2、LC2 和 MC。因此，AC1 有更多的机会利用 NRW，并且 2.5°C 的升温确实会导致碳交换发生显著变化。结构方程模型进一步表明，空气温度对 AC 碳交换最重要，但对 LC2 和 MC 与 NRW 同等重要；升温对 AC 碳输入的积极影响远强于后者。因此，温度对生物结皮碳输入的影响取决于水分和光照。同时，在未来研究生物结皮对气候变化的响应时，应充分考虑 NRW 的作用、AC 之间的过渡状态以及地衣结皮明显的固碳差异。
