Table 5. Forest Inventory and Analysis (FIA) data.

Region	Number of plots (n) andforest area randomlysampled (ha)	Mean FIA stand age (yrs)		Test for difference in stand initiation since 1930 vs. 1800–1900: Chi-square, P
		Current	In 1930
Sierra Nevada (main)	n = 232 338,400	148	97	86.3, <<0.001
E. Cascades and E. Sierra Nevada	n = 135 192,000	155	114	25.4, <<0.001
Klamath Mountains	n = 251 372,000	157	111	43.9, <<0.001
Central Rockies	n = 276 446,400	105	75	58.9, <<0.001
Northern Rockies	n = 1929 3,244,800	105	70	333.8<<0.001
Southwestern US	n = 319 492,000	116	59	188.2<<0.001

Area of sample population randomly sampled, mean stand age currently, and in 1930, and Chi-square test results.