A neutral modeling approach for designing spatially heterogeneous jack pine plantations in northern Lower Michigan, USA

Abstract

Jack pine-dominated ecosystems in northern Lower Michigan are heavily managed using a harvesting and planting regime designed to provide breeding habitat for the federally endangered Kirtland’s warbler. These plantations do not resemble naturally-regenerated patterns of jack pine, but few data exist after which alternate planting configurations may be modeled. Our objective was to use quantitative analyses to construct new planting configurations that better mimic the spatial patterns of natural post-fire regeneration. We used high-resolution color imagery of a 2000 wildfire to map jack pine saplings and the point density function in ArcMap to quantify the spatial heterogeneity that follows large wildfires in this region. Based on metrics calculated from this analysis of landscape pattern, we used a neutral modeling approach to develop prototypical planting configurations. Jack pine regeneration in the burned area occurred as a series of high-density patches within a matrix of moderate- to low-density regeneration. In contrast, the planted areas were dominated by a single, high-density class with large patch sizes and little heterogeneity. We were able to construct neutral models that were not significantly different from the actual landscape using the metrics we calculated. Though highly successful for Kirtland’s warbler habitat, current jack pine plantations in northern Lower Michigan do not emulate natural post-fire patterns. Quantifying the spatial pattern of regeneration following wildfires may inform neutral landscape models, which will be important tools for managers as they attempt to better emulate natural patterns within plantation design.