Application Of Gini Coefficient In Seed Germination Strategy Of Common Plants From Alpine Meadow On The Tibet Plateau

How to deal with sudden natural disasters and resist the harsh natural environment is a problem that plant seeds must face in variable environment.The seeds of different plants usually take different germination strategies to reduce the risk on a time scale.In general,it is difficult to measure the seed germination strategy by a single index such as seed germination percentage,germination rate or initial germination time.In this study,the Gini coefficient was modified to quantify risk spreading of plants in the germination process,and the germination strategy of the seed was studied.Based on testing of seed germination of 151 plant species of different families from an alpine meadow on the Tibet Plateau,the Gini coefficient of these species were calculated was calculated and compared with seed germination percentage,germination rate and initial germination time.Furthermore,the effects of altitude and temperature on Gini coefficient,germination percentage,germination rate and initial germination time were discussed.This paper can be used as an important supplement to the study of seed germination ecology in alpine meadow on the Tibet Plateau.The results showed:1.Gini coefficient has a significant correlation with seed germination percentage,germination rate,and initial germination time.The species with high Gini coefficient usually have a higher seed germination percentage,faster germination rate and shorter initial germination time,and vice versa.Because of the ecological significance of Gini coefficient and its relationship with other indexes in seed germination,it can be used as a comprehensive index to measure seed germination strategy.2.The germination strategies of 151 plants in this study can be divided into radical strategies and conservative strategies.For plant communities,the diversity of seed germination characteristics and strategies of plants in the studied alpine meadow maybe one reason for coexist of these plants.3.Altitude significantly affected the seed germination behavior and germination strategy.With the rise of elevation,the Gini coefficient,seed germination percentage and germination rate decreased significantly,altitude could explain this change by 15.6%,4% and 4.5% of the total variation.The initial germination time of seeds increased but not significant.This suggests that as the altitude increases,the germination strategy of the seeds get more conservative,which may be related to the harsh natural conditions at high altitudes.The conservative strategies are beneficial to reduce the risk of perish in a short time and have a better fitness.4.Temperature also can significantly affected seed germination behavior and germination strategy.With the increase of temperature,Gini coefficient,seed germination percentage and germination rate increased significantly,temperature could explain this change by 15.7%,14.9% and 51.6% of the total variation.The initial germination time of seeds decreased significantly,and temperature could explain this change by 51.2%.When the outside temperature is 5?~25?,seed germination strategy of most plants will get more radical with the increase of temperature,and 20?~25? is the optimum germination temperature for seed germination.The temperature range is close to the temperature of soil surface in the studied site in spring and autumn.To some extent,the difference between the optimum germination temperatures of plants coexist in the same community reflects the niche differentiation of this community.Thus,it can explain the coexistence of these species.In addition,the seed germination strategy may also be affected by habitats or other factors,the correlation between them also need to be studied in the future.