黄土高原土壤生物结皮对植物种子出苗和生长的影响

Effects of Biological Soil Crusts on Seed Emergence and Seedling Growth in Loess Plateau,North Shaanxi Province

为了解生物土壤结皮对植物种子萌发出苗和植物生长的影响,于2009年7～8月在陕西省吴起县进行野外调查,对油松(Pinus tabulaeformis)、柠条(Caragana korshinskii)、沙棘(Hippophae rhamnoides)和杜梨(Pyrus betulae-folia)种子进行萌发实验,研究生物结皮与植被之间的相互关系以及完整结皮、破碎结皮和覆土处理对这4种种子出苗和生长的影响。结果表明:随着生物结皮盖度和厚度的增加,植被盖度和数量显著减少(P<0.01),植被种类有增加的趋势(P>0.05);植物种子类型和结皮类型显著影响种子的出苗率和出苗过程(P<0.01),但两者的交互效应对出苗率影响较小(P>0.05),而对出苗过程影响显著(P<0.01);破碎结皮下的出苗率较完整结皮下的高,与覆土下的种子出苗率无显著差异,是否减慢出苗速率因植物种子类型而异;破碎结皮增加了植物的生物量,覆土条件下的植物根冠比最大,完整结皮是否影响植物的生物量和根冠比因植物种子类型而异。

Biological soil crusts are prevalent in arid and semiarid regions,they are the complex mixtures of cyanobacteria,green algae,phycolichens,mosses,liverworts,fungi and bacteria.In order to understand the effect of biological soil crusts（BSCs） on seed emergence and seedling growth in loess region,we conducted field surveys and studied the impact of intact crusts,broken crusts and soil on seed emergence of 4 plant species including Pinus tabulaeformis,Caragana korshinskii,Hippophae rhamnoides and Pyrus betulifolia based on the field emergence experiment in Wuqi County,Shaanxi Province during the period from July to August 2009.The results reveal that the vegetation coverage was reduced significantly with the increase of BSCs coverage and thickness（P0.01）,and vegetation types were in an increase trend（P0.05）.Seed emergence rate and emergence process were affected by plant species and crust types（intact crusts,broken crusts and soil）（P0.01）,and the interaction between the two affected slightly the seedling emergence（P0.05）,but affected significantly the emergence process（P0.01）.The seed emergence rate under broken BSCs was higher than that under intact BSCs,but there was no significant difference with soil.Broken BSCs could increase plant biomass and root-shoot ratio of plants,but intact BSCs affected the plant biomass and root-shoot ratio depending on the types of seed.