Section 1: Overview
Background
More than 800,000 acres of roadsides associated with Texas highways are vegetated. Most of these acres will be under vegetation management level 2 (as described in
). These rights of way include all ecological regions of Texas and represent a cross-section of the state’s varying landscapes. They range from humid prairies and forests in the southeast and east to desert shrub, grassland and forests in the mountainous region of west Texas.
These landscapes support more than 900 species of wildlife and about 5,500 species of vascular plants including 2,000 different wildflowers. Because roadsides within these landscapes provide habitat for a wide variety of plants and wildlife, they are vital to their continued existence.
This section explains why the rich natural resource heritage found along roadsides should be conserved and managed as a part of the Texas highway system.
Threat of Habitat Degradation
Habitat degradation and loss is now the most significant problem
associated with maintaining healthy populations of wildlife and
plant resources. The adverse effects of habitat destruction have become
a national and global concern.
Extent of Habitat Degradation
More than one-half of the wetland habitats in the continental
United States have disappeared. Land use changes have resulted in
similar losses of coastal wetlands in Texas. Almost two-thirds of
hardwood bottomlands (one of the more important habitats) are now
gone. In the lower Rio Grande Valley, more than 95 percent of native
brush has vanished. Native longleaf pine forests have declined from
an estimated six million acres to less than one million acres. Some
95 percent of the originally occurring native prairies have also
disappeared.
Remaining habitats have suffered too. Human development has
fragmented them. Poor land management practices have modified them.
And the introduction of exotic plants and animals has displaced
native species.
Significance of Roadsides
As native wildlife and plant habitats continue to decline,
those that do remain gain importance. Remaining habitats are important
both to the resources dependent on them and to the public. Increasingly,
the public views natural resources as part of our Texas heritage.
Thus roadsides, through their permanence and statewide distribution,
have gained importance as plant and wildlife habitat.