Stand structural characteristics were quantified within an 11,000
ha longleaf pine savanna in the Gulf Coastal Plain. Past management
within the study landscape included annual dormant season burning,
removal of dead longleaf pines, and hi-grade logging of pine. In
1987, the landscape came under reserve status which greatly altered
management activities. Current management includes annual dormant
season fire with occasional growing season fire, debris retention,
and cessation of logging.
The objectives of the current study were to 1) quantify current
stand structural characteristics, including composition, tree age
and size distributions, horizontal canopy structure, and large woody
debris loadings, 2) assess deviation of structure away from that
characteristic of an old-growth condition, and 3) quantify recent
dynamics in structure that have resulted from the shift in
management.
While all stands are dominated by longleaf pine, the importance
of several oak species in larger size classes is greater then in
old-growth savannas. Increased oak importance results from a long
history of dormant season fire. In most stands longleaf pine
populations are uneven-aged, with trees concentrated into several
cohorts. This contrasts with the balanced all-aged distribution
typical of old-growth stands. Some stands do contain large, old
trees (up to 170 years old) but past logging has reduced their
number well below that found in old-growth stands. Further, dormant
season burning has greatly reduced longleaf pine advanced
regeneration, as evidenced by the lack of individuals in smaller
diameter classes. Horizontal crown cover is low, similar to
old-growth savannas. However, exposed crown area is concentrated in
larger diameter classes, again reflecting a lack of advanced
regeneration. Many stands do contain large populations of seedling
longleaf pine that established during a massed seed year following a
growing season fire in 1987. Large woody longleaf pine debris has
rapidly developed since the change in management. While numbers of
snags and logs per unit area in some stands is approaching levels
similar to old-growth stands, size and decay distributions are
weighted towards smaller, less decayed debris.
Future management activities which might be used to hasten
development of old-growth structure include continued growing season
burning at variable frequency, oak removal, creation of debris by
killing larger trees, and planting of longleaf pine to facilitate
development of diverse age and size structure.
 |
|
|
| |
|
|
|
