This term is defined as the distribution of tree sizes and species on a forested area. Stand originates in a short period of time usually 10 - 20 years. Trees are fairly consistent in height with variation depending on crown position in canopy namely whether a tree is dominant, co-dominant, intermediate or suppressed. Stand consists of many ages and tree sizes.
Trees originate more or less continuously.
Get J-shaped curve when plot TPA versus DBH class. Either a stand is overstocked or understocked . Most natural stands are understocked. Note that the spacing of trees is not taken into consideration. It is said that SDI is independent of site quality and stand age.