Title: Classification of Vegetation Communities of Maryland
Classification of Vegetation
Communities of Maryland: First Iteration
A Subset of the International Classification of Ecological
Communities: Terrestrial Vegetation of the United States
Format of this Document
This publication presents a Maryland subset of the current
International Classification of Ecological Communities. Data used have been
extracted from NatureServe biological conservation databases and are current as
of April 2003. The format in which the classification is presented, and the
current completeness of information in various fields in the classification,
requires some explanation.
The classification is presented in the order of the hierarchy.
Only those hierarchy units currently documented or suspected to occur in
Maryland with a high degree of confidence are presented. The hierarchy is
presented in full in Grossman et al.
1998. The complete hierarchy offers a broad
perspective on the physiographic/floristic structure on the classification. The
hierarchical presentation of the alliances and associations generally places
closely related vegetation types near one another. Thus, the Forest Class
(vegetation dominated by closed canopies of trees) is followed by the Woodland
Class (vegetation dominated by open canopies of trees). All mixed needle-leaved
evergreen-cold-deciduous forests will be found together in the Mixed
Evergreen-Deciduous Forest Subclass. Of course, such a linear ordering of types
that does not and cannot capture all relationships, and sometimes communities
that are closely related floristically are separated widely by the physiographic hierarchy. For instance,
Mixed Needle-leaved Evergreen –Cold deciduous woodlands are group together in
II.C, separate from the Mixed Needle-leaved Evergreen-Cold deciduous Forests.
Some examples of close relationships that are particularly prone to cut across
the hierarchy are:
Forests (I) and Woodlands (II). The structure of the hierarchy
between the Forest Class and the Woodland Class is relatively parallel, and in
many cases, forests and woodlands with similar composition may be found in both
In the "woody classes," Forests (I), Woodlands (II), Shrublands
(III), and Dwarf-shrublands (IV), there are often close relationships between
"mixed evergreen - deciduous" (Subclass C) and both "evergreen" (Subclass A) and
"deciduous" (Subclass B). This is especially true in most parts of the
Southeast, where there is not a strong dominance of either deciduous or
evergreen life strategies; species with both strategies often occur in variable
mixtures, and two closely related associations may be best placed in different
subclasses because of a difference in prevalent dominance of several evergreen
and deciduous species.
Woodlands (II) and Shrublands (III) with particularly open woody
structure are often closely related to herbaceous types (V), especially
Sparsely Vegetated (VII), Nonvascular (VI), and Herbaceous (V)
are often closely related.