Plant Community Succession Following Disturbances in a Pine Barren and Adjacent Hardwood Forest

Abstract

The sandstone pavement barren and adjacent cobblestone formations in Clinton County, New York were created by the sudden release of water from glacial Lake Iroquois approximately 12000 ybp. Today, the barren is a rare ecological community type in New York State, dominated by jack pine, a species that can tolerate a water- and moisture-deficient soil. The soil in the cobblestone deposits supports hardwood trees such as northern red oak, sugar maple, red maple, and American beech.

In January 1998, several days of freezing rain in the Northeast blanketed 10 million ha with 2 to 10 cm of ice. Two million ha of forests were severely affected, including the pine barren and adjacent forests in Clinton County, New York. This study investigated the effects of the ice storm and subsequent "restoration cuttings" on plant community succession in the pine barren and adjacent hardwoods. The William H. Miner Agricultural Research Institute, Chazy, New York owns the eight stands sampled in this study.

Both disturbance types had dramatic effects on plant community structure. Nearly half of the hardwood trees were severely affected by the ice storm, but most survived through epicormic branching. Understory trees and regeneration proliferated beneath the temporary canopy gaps in the main canopy. Overstory species are represented in the regeneration size classes, with shade-tolerant species being most important. In the hardwoods, neither the ice storm or restoration cuttings caused plant community succession in the strict definition; the disturbances caused shifts in importance of species present at the time the disturbances occurred rather than a replacement of one plant community by another.

In the pine barren, ice storm damage was especially intense, causing severe crown breakage in more than half of the pine trees. The majority of pine trees were killed by the ice storm and no pine seedlings were observed in the ice storm-damaged stands. Moderate amounts of jack pine regeneration (between 18000 and 24000 stems per hectare) were found in the areas treated with a restoration cutting. This amount of jack pine regeneration was considered sufficient to replace the original stand.

The future of ice storm-damaged, uncut stands in the barren is not promising. Here, the majority of pine trees are standing dead stems and the regeneration, while sparse, is primarily red maple. Without silvicultural intervention, ice storm damaged areas of the barren will have a shift from dominance by jack pine to heath shrubs, especially black huckleberry. The restoration cutting showed that mechanical treatment, while not as effective as fire in regenerating jack pine, can bring about adequate amounts of jack pine regeneration, along with red maple, white birch and gray birch.