The Ecological Response Of The Vegetation Concrete With Five Kind Of Pioneer Species

The vegetation concrete ecology protection technology (CBS), combining organicallyslope surface protection with vegetation restoration, is a good ecological slope protectiontechnology with high effects and resolve the key problem in traditional engineering slopeprotection technology which can not improve ecological environment. Vegetation concretematrix material includes cement, soil, organic matter (wood), green additives, compoundfertilizer, etc. In the vegetation concrete ecology protection technology, determiningscientifically the content of cement content is a crucial technical problem. On the one hand,the increase of cement content can strengthen protection function of slope; on the otherhand, seed germination, seedling establishment and growth may decrease with the increaseof cement content. Control experiments were applied in our study which employed fivepioneer species, including Cynodon dactylon, Lolium perenne, Festuca arundinacea,Magnolia multiflora and Medicago sativa, and five cement content treatments rangingfrom0to16%at4interval. The changes in seed germination percentage, seedling survivalrate, seedling growth (including leaf number, seedling height, seedling biomass andseedling growth (including plant height, leaf number, aboveground biomass, belowgroundbiomass, root length, root surface area) and seedling photosynthetic physiologicalcharacteristics (including Net photosynthetic rate, Stomatal conductance, Transpiration rateand Intercellular CO2concentration) were tested to uncover the effects of cement contentand optimal cement content in the vegetation concrete matrix, and to improve thevegetation concrete ecology protection technology (CBS).The results showed that different cement content had a significant influence on seedgermination, seedling establishment and seedling growth of the five species. The cementcontent of less than8%promoted seed germination of five species meanwhile seedgermination was stressed when the cement content was over8%. The survival rate ofseedlings of five plants ranked the highest when the cement content was at0%, butdecreased gradually with increasing cement content. Leaf number, plant height, biomass,root growth parameters of seedlings of the five species increased with the increase ofcement content from0%to8%, but decreased with the increase cement content from8%to16%. In the five species, Medicago sativa, Magnolia multiflora, Lolium perenne andCynodon dactylon ranked the highest in biomass, leaf number, root growth and seedlingsurvival respectively, this implied that each of these four species adapted to theenvironment in different ecological characteristics. The cement content also influencedsignificantly the photosynthetic physiology of five species. With the increase of cementcontent, the photosynthetic physiological characteristics, including the net photosyntheticrate (Pn), stomatal conductance (Gs), transpiration rate and intercellular CO2concentration(Ci), all changed significantly. The changes of photosynthetic physiological parameters ofspecies differed among different cement content treatments. Overall, the photosyntheticphysiological activities of plants at low cement contents were higher than that at the highcement content. The plant of Festuca arundinacea had the strongest physiological activityin the five species. To sum up, the cement content in the vegetation cement matrix had significant effects onseed germination, seedling establishment and seedling growth of pioneer species. Theecological response differed to the change of cement content among the five species.However, certain cement content in the vegetation cement matrix could promote seedgermination, seedling settlement and growth. All the indexes reached the highest levelwhen the cement content at8%, which suggested that the cement content of8%was thesuitable cement content for the application in the vegetation concrete ecology protectiontechnology. The cement content, species or seed amount should be changed according tothe need in the specific engineering program.