Vegetation of The Ossipee Pine Barrens Preserve: Description, Classification, and Successional Trends. Carroll County, NH

Title: Vegetation of The Ossipee Pine Barrens Preserve: Description, Classification, and Successional Trends. Carroll County, NH

Author: Claire Dacey, UVM. Prepared for TNC-NH


Abstract: The Ossipee Pine Barrens Preserve is a high-quality example of the globally-rare Northeastern Pitch Pine-Scrub Oak Barrens natural community. In addition, it provides habitat for a number of globally rare moth and regionally-declining songbird species. Active fire-suppression over the last four decades threatens this rare community with succession to more common vegetation types, and loss of habitat for rare fauna. As part of its mission to protect biodiversity, The New Hampshire Chapter of The Nature Conservancy is planning active management to maintain both the mosaic of pine barrens vegetation found on the site, and habitat for the rare moths and declining songbirds.

To aid in management planning, I used analysis of current and historical aerial photos, data from 32 study plots and 10 observation points, and multivariate analysis to classify the vegetation of the Preserve into eight types, and to map and describe these types. Additionally, using historic aerial photos and field evidence of fire and logging, I attempted to reconstruct the patterns of vegetational change over the last 60-100 years. Using both evidence of past change and current data on seedlings and saplings, I created a model predicting successional changes for the current vegetation in the absence of disturbance.

I concluded that succession at the Ossipee Barrens is generally slow relative to many of the more southerly examples of this community. However, in the longterm, the absence of disturbance will lead to the replacement of much of the barrens vegetation with white pine and hardwoods such as red maple. Establishment of white pine and hardwoods appears to be slowest in areas with the most open canopies, accelerating as canopies close and the cover of scrub oak and blueberry decreases. Currently 11-18% of the Preserve appears to be occupied by relatively stable, open-canopied vegetation that has changed little in over 60 years. Another 50% or so is in open to semi-open canopy types that resulted from logging in the 1970s, and are at more immediate risk of succession to closed-canopy forest. Around 25% of the Preserve is covered in closed-canopy, pitch-pine dominated forests. Some of these forests are relatively young – arising from clear-cuts in the 1930s – while others appear to have been undisturbed for much of the last century, and have a good deal of hardwood regeneration. A variety of non-pitch pine riparian communities occupy the remainder of the Preserve. These communities were not described in this study.

I recommend that permanent plots be established throughout the Preserve to monitor both successional change and vegetation responses to management applications. This is the best way that the dynamics of vegetation change on the Preserve can be understood. The final chapter of this document contains recommendations for plot establishment specific to each vegetation type, with the exception of riparian areas.