维管植物和生物土壤结皮的镶嵌式分布是中亚荒漠区地表覆盖的主要形式。在这一地区，生物土壤结皮占据了地表40%以上的面积，由于生物土壤结皮的潜在光合能力与维管植物相当，据此推测，结皮发育土壤在干旱区碳循环中可能具有重要的作用，然而，相关的研究多集中于室内条件下生物土壤结皮的光合生理测定方面。
中科院新疆生态与地理研究所张元明研究员领导的“生物土壤结皮生态学”研究团队在“973”项目和国家自然科学基金的资助下，围绕干旱荒漠区生物土壤结皮发育土壤的碳通量特征这一科学问题，实测研究了古尔班通古特沙漠生物土壤结皮在荒漠土壤-大气界面碳交换中的作用。
研究表明，生物土壤结皮在土表的发育显著阻碍了土壤CO2向大气的释放，地表生物土壤结皮能有效减少1/4至1/2的土壤碳释放，显著影响土壤-大气界面碳交换过程。这一结果说明，生物土壤结皮在荒漠土壤-大气界面碳交换中扮演重要角色。在这一生态过程中，自然条件下土壤水分和温度的耦合关系起着关键性作用。温度变动（10至300C）对生物土壤结皮的光合作用无显著影响，但温度的升高却能显著刺激土壤呼吸；相反，低温能延长结皮光合活性时间，增加了结皮发育土壤的碳截获量。这一结果暗示，早春融雪和积雪覆盖期可能是生物结皮发育土壤碳截获的主要时段。（生物谷Bioon.com）
生物谷推荐的英文摘要
Soil Biology and Biochemistry doi.org/10.1016/j.soilbio.2012.12.006
Carbon flux in deserts depends on soil cover type： A case study in the Gurbantunggute desert， North China
Y.G. Su， L. Wu， Z.B. Zhou， Y.B. Liu， Y.M. Zhang
Carbon flux represents carbon uptake from or release to the atmosphere in desert ecosystems， yet the changing pattern of carbon flux in desert ecosystems and its dependence on soil cover type and rainfall amount are poorly understood. We measured net carbon fluxes (NCF) in soil with four cover types (moss crusted soil， cyanobacteria/lichen crusted soil， bareland and semishrub Ephedra distachya-inhabited site) from April to October of 2010 and 2011， and NCF and dark respiration (DR) after four rainfall amounts (0， 2， 5， and 15 mm) in cyanobacteria/lichen crusted soil， bareland and the E. distachya-inhabited site. NCF in the E. distachya-inhabited site differed significantly from those of the other three soil cover types， while no difference was observed between the moss and cyanobacteria/lichen crusted soils or between the two crusted soils and bareland on most measurement occasions. NCF ranged from 0.28 ± 0.14 to 1.2 ± 0.07 μmol m2 s1 in the biologically crusted soils， and from 2.2 ± 0.27 to 0.46 ± 0.03 μmol m2 s1 at the E. distachya-inhabited site. Daily NCF in the biologically crusted soils and bareland showed carbon release at most times and total carbon production ranged from 48.8 ± 5.4 gC m2 yr1 to 50.9 ± 3.8 gC m2 yr1， while the E. distachya-inhabited site showed a total carbon uptake of 57.0 ± 9.9 gC m2 yr1. Daily variances in NCF were well-explained by variances in surface soil temperature， and seasonal NCF showed a significant linear relationship with soil moisture in the two biologically crusted soils and bareland when soil volumetric water content was less than 3%. Rainfall elicited intense carbon release in cyanobacteria/lichen crusted soil， bareland and at the E. distachya-inhabited site， and both NCF and DR were positive in the first two days after rainfall treatments. Mean NCF and DR were not different between rainfall amounts of 2， 5 and 15 mm in cyanobacteria/lichen crusted soil and bareland， while they were significantly higher after 15 mm rainfall treatment compared with 2 mm and 5 mm treatments at the E. distachya-inhabited site. Mean NCF and DR in the first two days increased logistically with rainfall amount. Based on our findings， we suggest that E. distachya-inhabited sites contribute to carbon uptake in the Gurbantunggute Desert， while biologically crusted soils exhibit carbon release for most of the year. Even though photosynthesis immediately following rainfall can be stimulated， carbon uptake effect in biologically crusted soil is likely intermittent and confined to periods when moisture is available.
