Principal components (Z=U'X) of p-dimensional environmental factors in few populations were turned into a linear expression of primary data(X = UZ). The estimate error was named dj. EGA(PCr)s were calculated according to principal component analysis (PCA) of 6-dimensional environmental factors among the twenty provenances of American elm.The cumulative contributions of 3 .EGA(PCR)s selected according to eigenvalue were 63.8%, 84.3% and 96.0%, respectively. Most information from environmental factors was con...