梭梭林下土壤结皮对黄花补血草种群分布格局影响

Effects of soil crusts on the population distribution pattern of Limonium aureum in degraded Haloxylon ammodendron forests

为揭示梭梭(Haloxylon ammodendron)林下不同结皮类型对黄花补血草(Limonium aureum)种群分布格局的影响特征,以石羊河流域下游退化梭梭林下不同类型土壤结皮中的黄花补血草种群为研究对象,揭示无结皮(no crust stage,NCS)、物理结皮(physical crust stage,PCS)和生物结皮(biological crust stage,BCS)类型中黄花补血草种群分布格局。结果表明:1)土壤结皮的形成对黄花补血草种子捕捉、萌发及定居发挥着积极的作用,NCS类型由于地面流动性大,种子不易获得适宜萌发条件,造成NCS黄花补血草种群密度显著低于PCS和BCS类型(P<0.05);2)不同土壤结皮类型的黄花补血草种群株高无显著差异(P>0.05),种群平均冠幅在PCS和BCS类型显著低于NCS(P<0.05),而PCS和BCS种群盖度显著高于NCS(P<0.05),土壤结皮的形成对降水产生了重新分配,进而影响了种群生长状况;3)NCS类型黄花补血草种群分布稀疏且不均匀,偏向于小株型化,而PCS和BCS类型黄花补血草种群分布密集,形成了稳定的种群,且大植株数量相对于NSC类型有所增加;4)在NCS、PCS、BCS类型中黄花补血草种群空间分布格局均表现为聚集分布,但聚集强度有一定差异,聚集强度排序为BCS类型>PCS类型>NCS类型。因此,结皮类型对黄花补血草种群基本特征、年龄结构及空间分布格局有显著影响,结皮的形成促进了黄花补血草种群的定居和分布,种群密度大,且相对稳定。研究结果可为退化梭梭林人工植被恢复提供参考。

To determine the effect of subsoil crusts on the distribution pattern of Limonium species in Haloxylon ammodendron forest,we chose L.aureum in a degraded H.ammodendron forest in Shiyang River basin as the research subject and determined the distribution pattern of L.aureum in the no crust stage(NCS),physical crust stage(PCS),and biological crust stage(BCS).The results showed that(1)the formation of soil crusts played a positive role in seed capture,germination,and settlement of L.aureum.Owing to the high ground mobility,it was difficult to obtain suitable germination conditions for seeds in non-crusted areas.Therefore,the population density of L.aureum in the NCS plot was significantly lower than that in the PCS and BCS plots(P<0.05).(2)The height of L.aureum was not significantly different in the different soil crust types(P>0.05).The average crown width of L.aureum in the PCS and BCS plots was significantly lower than that in the NCS plot(P<0.05),whereas the population coverage of L.aureum in the PCS and BCS plots was significantly higher than that in the NCS plot(P<0.05).Soil crust formation caused a redistribution of precipitation,which affected the growth of the population.(3)The population distribution of L.aureum in the NCS plot was sparse and uneven,and was the small plant type.The population distribution of L.aureum in the PCS and BCS plots was dense,forming a stable population,and the number of large plants was higher than the number in the NCS plot.(4)In the NCS,PCS,and BCS plots,the spatial distribution pattern of the population of L.aureum showed aggregation distribution;however,the aggregation intensity was different.The order of the aggregation intensity was as follows:BCS>PCS>NCS.Thus,the crust type influenced the basic characteristics,age structure,and spatial distribution pattern of the L.aureum population significantly.Crust formation promotes the settlement and distribution of the L.aureum population.The population density is large and relatively stable.The study provides a reference for the restoration of artificial vegetation of degraded H.ammodendron.