STRUCTURE AND DYNAMICS OF HARDWOOD SWAMPS IN THE NEW JERSEY PINE BARRENS: CONTRASTING PATTERNS IN TREES AND SHRUBS

Abstract

The biomass, density, age structure, and dominance patterns of the tree and shrub populations in hardwood swamps of the New Jersey Pine Barrens are described and contrasted with each other. The total biomass of individual swamps ranges from 92,000 kg/ha to 194,000 kg/ha, depending on the age of the stand. These biomass values are similar to those reported for southern hardwood swamps. The Pine Barrens swamps are distinguished by very large populations of ericaceous and other shrubs, which range up to 13% of the total above‐ground biomass. The tree populations, composed principally of Acer rubrum, Nyssa sylvatica and Magnolia virginiana, are even‐aged; Acer is strongly dominating, with a minimum of 73% of the biomass, and species richness is associated with the availability of different microhabitats. The shrub populations, by contrast, are all‐aged, with the dominance patterns among the species and the stand biomasses varying with the degree of flooding of the stand. Differences in size and growth rate among the shrub species parallel their evident response to the flooding gradient. The shrub stratum has lower species richness than the comparable southern swamps and floodplains, but ranges up to higher biomass values.