Study On Restriction Mechanism Of Berberis Population Regeneration In West Tianshan Wild Fruit Forest

Berberis is a unique companion species of the Xinjiang West Tianshan wild fruit forest.It plays an important and irreplaceable role in the geographical climate,biodiversity and ecological defense system of the Yili river basin.In this study,the Berberis population distributed in the West Tianshan wild fruit forest was studied.The community structure,soil seed bank and seedling bank,seed germination barrier mechanism and drought tolerance and salt tolerance of the seedlings were studied.The four aspects of population survival status,provenance limitation,propagation restriction and completion restriction reveal the limiting factors of the population regeneration in the west Tianshan wild fruit forest.To provide a scientific basis for the conservation,restoration and sustainable use of the wild Berberis population in the west Tianshan wild fruit forest.The main findings are as follows:(1)The structure of Berberis community can be divided into three layers:arbor layer,shrub layer and herb layer;the important value of shrub layer is 196.25%,and the complexity of species diversity in each layer is:herb layer>arbor layer>shrub layer.The temperate attributes of the flora of this community are more obvious,and the Berberis is a single-species and founding species of the community.The maintenance of the Berberis population depends on the middle-aged individuals,the saplings are less,and the age structure of the population is spindle-shaped,which is a degenerating population.(2)The intact seed accounted for 51.70%of the total number of seeds in the Berberis soil seed bank,98.60%of the intact seeds were clustered in the litter layer.The three populations were all root saplings,and the root blasts allowed the seedlings to spread to 100 cm or more around the mother plants.Grade II seedlings(20 cm～40 cm)were the most abundant,accounting for 51.13%of the total number of seedlings;The conversion rates of the second and third grades(40 cm～60 cm)of Huocheng and Xinyuan population were lower,29.27%and 31.58%,respectively,and the Tekesi population was 77.78%.(3)The water permeability of the Berberis seed coat was similar.The seed coat of the Berberis atrocarpa Schneid.had a strong inhibitory effect on germination;while the seed coat inhibition of Berberis nummularia Bge.was not obvious;The germination rate of Berberis seeds gradually increased with the increase of 4℃ low temperature stratification time,When the Berberis atrocarpa Schneid.seed was planted for 90 days,the dormancy was basically relieved;when the Berberis nummularia Bge.seed was 30 days,the dormancy was basically relieved;The treatment of GA3 solution with the concentration of 200 mg·L-1 could significantly improve the germination rate of Berberis seeds.(4)With the extension of drought stress time and the increase of stress degree,the content of peroxidase(POD)and the activity of superoxide dismutase(SOD)in the leaves of Berberis seedlings increased first and then decreased;abscisic acid(ABA)content,free sulphate acid(FP)content and the malondialdehyde(MDA)content gradually increased.The drought resistance of the Berberis nummularia Bge.seedlings was better than that of Berberis atrocarpa Schneid..The correlation between the indicators and their drought resistance was as follows:POD content>FP content>MDA content>ABA Content>SOD activity.(5)With the increase of NaCl stress,the POD content and SOD activity in the leaves of Berberis seedlings increased first and then decreased.The ABA content and FP content of the leaves gradually increased;MDA content increased first,then decreased and finally increased.The comprehensive evaluation results of membership degree showed that the salt tolerance of the Berberis atrocarpa Schneid.seedlings was better than Berberis nummularia Bge..The correlation between the indicators and their salt tolerance was as follows:MDA content>POD content>FP content>ABA content>SOD active.