Describing a landscape mosaic: Forest structure and composition across community types and management regimes in inland northeastern pitch pine barrens

Abstract

Pitch pine (Pinus rigida Mill.) barrens are a globally rare, fire-dependent ecosystem of great ecological, social, and cultural significance found primarily in the northeastern US. In many cases, fire has been excluded from these systems leading to habitat degradation and biodiversity loss as pine barrens landscapes homogenize into closed-canopy forests of shade-tolerant, mesophytic species. This study aims to support the adaptive management of pine barrens ecosystems in the face of mesophication by contributing baseline information on their structure and composition. Specifically, we (1) assessed how stand conditions differ between community types and management strategies at the two sites and (2) placed this work in the broader context of pine barrens ecology and management. We sampled overstory structure and composition across five community types (successional northern sandplain grasslands, pitch pine-scrub oak barrens, pitch pine-scrub oak thicket, pitch pine-scrub oak woodland, and pitch pine-oak forest) and four management strategies (burning, thinning, burning and thinning, and no management). Differences in structure and composition between communities supported the concept of pine barrens as a landscape mosaic maintained by multiple unique disturbance regimes. Results suggest that burning, thinning, and their combination are all effective in maintaining conditions historically associated with pine barrens communities, and that a lack of active management may lead to a transition away from these characteristics. The range of pine barrens conditions documented in this and previous studies underscores the importance of management regimes that utilize a diversity of treatments applied at frequencies and intensities consistent with historic disturbance regimes for each pitch pine community type. Such strategies would maintain the mosaic of habitat conditions required to support the suite of species endemic to these communities, and would confer resilience to emerging stressors, such as southern pine beetle (Dendroctonus frontalis), which often generates greatest impacts in unmanaged, homogeneous forests.