Effects of spatial distribution and reproductive traits on the fitness of Stellera chamaejasme in alpine grassland
[Objective]To study the effects of spatial distribution and reproductive traits on the fitness of S.chamaejasme populations,and to explore the relationship between S.chamaejasme populations and en-vironment at different successional stages.[Method]The spatial distribution characteristics of the S.chamaejasme population were studied using RTK(i.e.,Real-time kinematic)technology;the individuals were divided into three classes according to the number of inflorescences as follows:class Ⅰ(1～10 branches),class Ⅱ(11～20 branches),and class Ⅲ(more than 21 branches).Then,the age structure of the population and the relationship between the reproductive fitness with population density and phenotypic characteristics of individuals were analyzed.[Result]Class Ⅰ seedlings accounted for 79%of the individuals tested,class Ⅱ seedlings for 14.4%,and class Ⅲ seedlings for 6.6%.The distribution of individuals in dif-ferent branches showed an inverted"J"curve,and the survival curve was Deevey Ⅱ,reflecting an age struc-ture of the growth stage of the population.Overall,the spatial distribution pattern of the population was characterized by cluster distribution,with slight differences among the three grades of individuals.The indi-viduals for classes Ⅰ and Ⅱ were obviously aggregated,while the adult plants tended to be randomly distrib-uted.Individual reproductive fitness was significantly positively correlated with plant density(R2=0.096,P=0.017),inflorescence density(R2=0.104,P=0.010),and the number of flowers per inflorescence(R2= 0.172,P=0.001).There was a negative correlation between the fitness and plant size(i.e.,inflorescence number)(R2=0.077,P=0.034),but not significant with plant height.[Conclusion]The S.chamaejasme population was characterized by the age structure of growth type and by spatial pattern of aggregation distri-bution,with significant effects of population density,plant size(i.e.,inflorescence number)and number of flowers per inflorescence on the fitness and no effect of plant height.
Stellera chamaejasmeage structurespatial distribution patternphenotypic traitsrepro-ductive fitness
NETL
NSTL
万方数据
