Characteristics Of Seed Germination And Seedling Growth Of Quercus Wutaishanica And Betula Platyphlla Based On Allelopathy Among Different Species And Habitat Difference

Quercus wutaishanica is the dominant species of Liupan Mountains.It grows well in a higher temperature environment,and plays an important role in the structure and community succession in this area due to its high shade drought tolerance.Betula platyphlla is the main pioneer associated with conifer species distributed in this area.It grows well in higher light,and it is drought-tolerant but not shade-tolerant.In this study,based on the allelopathic effects（the water extracts of withered leaves and soil）between species in the different community succession stages,as well as the effects of habitats difference such as light,drought stress,forest gap,slope position,litter,etc,the characteristics of seeds germination and seedlings growth of Q.wutaishanica and B.platyphlla were investigated.The results of this study would provide theoretical basis and scientific guidance for the regeneration of population and forest cultivation of deciduous broad-leaved forest in Liupan mountains.The main findings are as follows:1.The water extract from withered leaves of Pinus tabulaeformis promotes the seed germination of Q.wutaishanica,but shows a“low concentration promotion and high concentration restrain”mode to the seed germination of B.platyphlla.The water extract from withered leaves of Q.wutaishanica inhibits the seed germination of B.platyphlla.The seed germination percentage,germination rate and vigor index of Q.wutaishanica seed were higher than that of control（respectively were 83.33%,200.83 and 5.17）under different concentration treatment（5%,10%and 20%）of the water extract from withered leaves of P.tabulaeformis.The germination percentageof B.platyphlla seed under 10%treatment of the water extract from withered leaves of P.tabulaeformis was significantiy lower than that of control 41.25%（P<0.05）,and the gemination index and vigor index under each treatment were lower than that of control.The germination percentage,germination index and vigor index of B.platyphlla seed were reduced under different concentration treatment of the water extract from withered leaves of Q.wutaishanica,and the germination percentage and vigor index under 10%concentration treatment was significantiy lower than that of control 34.19%and 27.80%（P<0.05）.2.The water extract from soil of P.tabulaeformis forest inhibits the seed germination of Q.wutaishanica and B.platyphlla,and the water extract from soil of Q.wutaishanica forest shows a“low concentration promotion and high concentration restrain”mode to the seed germination of B.platyphlla.The seed germination percentages of Q.wutaishanica were decreased by 9.09%,10.91%,and 8.18%respectively under each concentration treatments（5%,10%and 20%）of the water extract from soil of P.tabulaeformis forest,and the vigor index under each treatment were lower than that of control.The seed germination percentage of B.platyphlla under 10%concentration treatment of the water extract from soil of P.tabulaeformis forest significantly lower than that of control 17.70%（P<0.05）,and the germination rate under each treatments were lower than that of control,and under 10%concentration treatment lower significantly than that of control 25.12%（P<0.05）.The seed germination percentages and germination rates of B.platyphlla reduced under high concentration treatments（10%and 20%）of the water extract from soil of Q.wutaishanica forest.3.Moderate light intensity is beneficial to the growth of Q.wutaishanica and B.platyphlla seedlings.The BSD,TDM,RGR,NAR,and RSR of Q.wutaishanica seedlings and the BSD,TDM,RGR,and RSR of B.platyphlla seedlings were highest under 18.9%NS treatment,and the BSD of former is significantly higher than that of 55.4%NS and 2.2%NS treatment,about 1.5 times of that（P<0.05）.The SLA reduced gradually with the increase of light intensity.And the SOD,POD and CAT activity decreased and then increased with the increase of light intensity.Total chlorophyll content decreased gradually with the increase of light intensity.The BSD,TDM,RGR and RSR of B.platyphlla seedlings under 18.9%NS treatment were higher than those of 2.2%NS treatment significantly（P<0.05）,about 1.5-2times of that.The CAT activity and total chlorophyll content decreased and then increased with the increase of light intensity.4.Drought stress restrain the growth of Q.wutaishanica and B.platyphlla seedlings,and with the increase of drough stress,the SH,LN,LAPP,RGR and NAR under 5.5%NS and 2.2%NS intensity of Q.wutaishanica seedlings all decreased gradually,as well as LAPP,TDM,RGR and NAR of B.platyphlla seedlings except 5.5%NS.Total chlorophyll content of Q.wutaishanica seedling leaves increased with the increase of drought stress under each light intensity,with the exception of 18.9%NS,were significantly different among drought stress and control（P<0.05）.Under severe drought stress,the SLA of seedling of 55.4%NS treatment was significantly lower than that of 5.5%NS treatment（P<0.05）.The POD activity of different drought treatment under 2.2%NS of B.platyphlla seedling leaves was significantly higher than that of control（P<0.05）.Total chlorophyll content under 55.4%NS decreased gradually with the increase of drought stress,was significantly different among drought stress and control（P<0.05）.Under 55.4%NS light intensity,the SLAs of seedlings in all drought stress treatment were lower significantly than other light intensity（P<0.05）.5.The forest gap and lower slope position are beneficial to the seedling growth of Q.wutaishanica and B.platyphlla,and under upper slope position,the SH,BSD,LAPP,TDM,SLA,SRL,and SSL of Q.wutaishanica seedlings under canopy is higher than that of seedlings under the forest gap,indicating the shade-resistance of seedling of Q.wutaishanica.Under the habitat of forest gap,the SH,BSD,LN,LAPP,RSR,SLA,and SRL of Q.wutaishanica and B.platyphlla seedlings grown at lower slope position were higher than that of seedlings grown at upper slope position,and SRL of former was significantly different between upper and lower slope position(respectively were 7.51 and 17.9 cm.g^-1)（P<0.05）.Under forest canopy,the RSR,SLA and SRL of two species seedlings grown at lower slope position were higher than that of seedlings at upper slope position.The SH,BSD,LAPP,TDM,SLA,SRL and SSL of B.platyphlla seedling in forest gap of upper slope position were higher than that of seedling in forest canopy.The survival rate,BSD,LN,LAPP and TDM of Q.wutaishanica seedlings in the forest gap of lower slope position were higher than that of seedlings in forest canopy,and significance difference was observed in all parameters of B.platyphlla seedlings.6.The habitat of forest gap is beneficial to the seedling growth of both Q.wutaishanica and B.platyphlla,on the contrary,disadvandage of the survival and growth of B.platyphlla seedling was detected in shade habitat.Litter coverage is no conducive to the seedling growth of two species.Under the forest gap,the survival rate,BSD,LN,LAPP,and TDM of both Q.wutaishanica and B.platyphlla seedlings litter coverage were lower than those seedlings of control.Whether litter-coverage or not,the highest SH and LAPP of Q.wutaishanica were observed under the habitat of forest gap.Seedlings grown at the edge of forest gap had the higher values of above paramenters while seedlings grown at forest canopy had the smallest ones.The SH（13.6 cm）and LAPP（50.52 cm²）of non litter coveraged Q.wutaishanica seedling grown at forest gap were significantly higher than that of the seedling at habitats of the forest gap edge（12.51 cm,33.11 cm²）and under forest canopy（11.94 cm,29.17 cm²）（P<0.05）.The BSD,LN,RSR,SLA,SRL and SSL of B.platyphlla seedlings coveraged by litter at the habitat of forest gap were higher than that of seedling at the forest gap edge,and all seedlings of B.platyphlla could not survived under forest gap edge when non-litter coverage,as well as under the habitat of forest canopy.