PARENT SESSION
Oral Session #56: Spatial Ecology: Pattern,movement,dispersal.
Presiding: G. Hartvigsen
Wednesday, August 7. 8:00 AM to 11:30 AM. Grand Ballroom West, Radisson.

Point pattern analysis of forest inventory stem-maps.

Woodall, Chris^*,1, Graham, Jon², ¹ USDA, USFS North Central Research Station, St. Paul, MN² University of Montana, Missoula, MT

ABSTRACT- The Forest Inventory and Analysis Program (FIA) of the USDA Forest Service currently maintains over 400,000 forest inventory plots across the United States, with all "in" trees stem-mapped. Point pattern analysis of the national inventory stem-maps has never been conducted to aid interpretation and estimation of forest attributes. In order to evaluate the techniques and benefits of conducting point pattern analysis using FIA data, Ripley's K(t) was calculated using various step-size distances (t) for over 600 FIA inventory plots in Minnesota and Wisconsin. The calculation of Ripley's K(t) can be reconciled with the FIA sampling design through inventory sub-plot truncation and recombination to produce accurate point pattern results. The scale (t) at which stem-map point patterns were most discernible as either clustered or uniform varied by forest type. In addition, K(t) values varied in accordance with changes in relative forest type shade tolerance and disturbance history. It was found that as shade tolerance and disturbance increased, so did tree clustering at varying scales (t) by forest type. Ripley's K(t) values can be determined for all FIA plots thereby refining ecological interpretations of the national inventory and providing an unprecedented spatial analysis of the United States' forests.

KEY WORDS: Ripley's K, inventory