Journal of The vertical development of early successional forestsEcology 1993, 81,271-285 in northern Michigan, USA

1. Studies have shown that differences in height growth rates are characteristic of tree species that differ in understory tolerance and relative successional status. Less-tolerant species have greater juvenile height growth rates than more-tolerant species and thus, in a mixed-species forest, the former gain an early competitive advantage after a stand-initiating disturbance. Species-level height stratification is, the predicted outcome under this model. 2. Silvicultural evidence suggests that a species-level differential growth rate model is idealistic because height stratification among species differing in understory tolerance is not consistently expressed within an even-aged forest. Stratification may fail to develop if individuals of a relatively tolerant species are competitively uninhibited, establish earlier than less-tolerant species, or are of vegetative-origin. 3. The establishment and height growth histories of three species differing in understory tolerance were examined within two forests in northern Michigan, • USA. Objectives of the study included: (i) determining if species height stratification paralleling understory tolerance was a characteristic of these forests; (ii) assessing • the degree of height variation within species populations; and (iii) determining i