A New Method for Delineating Tree Patches and Assessing Spatial Reference Conditions of Ponderosa Pine Forests in Northern Arizona

Multiscale spatial patterns of forest reference conditions offer insight on how historical and environmental processes have influenced forest stand dynamics. Yet, spatial information is often either unavailable or partial, because many studies provide nonspatial reference condition information, whereas others only report the local (i.e. observed at plot extent) spatial arrangement of trees. However, knowledge of multiscaled spatial patterns, including stand-, among-patch-, and within-patch-level patterns, is needed to ensure that forest management strategies suit a wide range of objectives in ecosystem restoration. In this study, we propose a new framework for delineating tree patches based on common stand attributes. We found that patch reference conditions for presettlement ponderosa pine in northern Arizona ranged from 10 to 27 patches/ha, accounted for 62-75% of the total historic stand basal area (m²/ha) and varied in size from 0.01 to 0.15 ha. Lastly, discussion was made on the importance of using a patch-delineation framework, such as the one proposed in this study, as a basis for quantifying stand- and patch-level patterns of reconstructed presettlement and current forest conditions and how this information should guide spatially explicit restoration management (e.g. thinning prescriptions).