Plant Interactions with Changes in Coverage of Biological Soil Crusts and Water Regime in Mu Us Sandland, China

Shuqin Gao1, Xu Pan1,3, Qingguo Cui1, Yukun Hu1,3, Xuehua Ye1*, Ming Dong1,2

1 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China, 2 Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou, China, 3 University of Chinese Academy of Sciences, Beijing, China * For correspondence. * E-mail: yexuehua@ibcas.ac.cn
生物土壤结皮的盖度和水分条件共同影响植物间的相互作用

在干旱区,降水稀少且不可预测,植物之间的相互作用往往表现为对水分资源的竞争。而干旱区土壤表层往往被生物土壤结皮所覆盖,结皮对于水分资源的再分配具有重要的影响。我们假设干旱区植物之间相互作用的强度和方向会受到生物土壤结皮的影响。为验证我们的假设,我们在温室里对14种4个植物种的不同组合进行了三种不同生物土壤结皮盖度和三种不同的水分施加处理,结果表明:1)生物土壤结皮改变了四个植物种之间的竞争强度,100%的生物土壤结皮覆盖极大地降低了目标植物种与相邻种之间的竞争强度,50%的生物土壤结皮覆盖增强了植物之间的竞争;2)生物土壤结皮对植物种间竞争强度的影响,会受到水分条件的修饰;3)植物间的相互作用具有种间特异性。

Abstract

Plant interactions greatly affect plant community structure. Dryland ecosystems are characterized by low amounts of unpredictable precipitation as well as by often having biological soil crusts (BSCs) on the soil surface. In dryland plant communities, plants interact mostly as they compete for water resources, and the direction and intensity of plant interaction varies as a function of the temporal fluctuation in water availability. Since BSCs influence water redistribution to some extent, a greenhouse experiment was conducted to test the hypothesis that the intensity and direction of plant interactions in a dryland plant community can be modified by BSCs. In the experiment, 14 combinations of four plant species (Artemisia ordosica, Artemisia sphaerocephala, Chloris virgata and Setaria viridis) were subjected to three levels of coverage of BSCs and three levels of water supply. The results show that: 1) BSCs affected plant interaction intensity for the four plant species: a 100% coverage of BSCs significantly reduced the intensity of competition between neighboring plants, while it was highest with a 50% coverage of BSCs in combination with the target species of A. sphaerocephala and C. virgata; 2) effects of the coverage of BSCs on plant interactions were modified by water regime when the target species were C. virgata and S. viridis; 3) plant interactions were species-specific. In conclusion, the percent coverage of BSCs affected plant interactions, and the effects were species-specific and could be modified by water regimes. Further studies should focus on effects of the coverage of BSCs on plant-soil hydrological processes.