Threats to Ecosystems

Ecological threats

The increase in invasive brush species in Gulf Coast prairies and marshes has had a negative impact on natural resources, native plant communities, and management activities associated with them. In the worst case scenario, the exotic species dominate the area creating a monoculture that decreases biological diversity. As a small fraction of the entire ecoregion, this issue has not been the case for Palmito Ranch Battlefield with little impacts on the way it looks between today and the battle time compared to other parts of the region. From an ecological perspective, prairie habitat patches that are dispersed and not connected in the landscape have a negative influence on the survival of native species dependent upon these grasses. For example, Attwater’s prairie chickens need 80,000 acres of connected grasslands to survive, and yet habitat patches in different places of a few hundred to a few thousand acres are insufficient to support them. Other native species such as bobwhite quail and the mottled duck are experiencing dramatic declines in populations as well due to the loss of prairie and wetland habitats in this ecoregion. Although prescribed or controlled burns are an effective management tool to sustain the native prairie grasses by controlling the short woody plants and allowing herbaceous plants to be more vigorous and productive, its use has been increasingly limited due to the growing amount of land occupied by cities and homes in this region.

Wildlife Species Threats

A species of great concern to the U.S. Fish and Wildlife Service is the ocelot, an endangered cat whose numbers have dwindled to fewer than 50 in the United States. The Mid-Delta Thorn Forest, a biotic community that once covered much of the delta, is a hunting ground for this nocturnal species. Texas ebony, Granjeno, and colima are but a few of the trees and shrubs that house an array of small mammals and birds, which are prey for the ocelot. Typified in remnant strips along fence rows, canals, and ditch banks, the diminished thorn forest habitat forces the solitary ocelot to cross open fields and risk the dangers of vehicular traffic and predators. The endangered species present within the Palmito Battlefield region are an indicator to the biodiversity of the lower Rio Grande ecosystems, therefore relating to the experience of the battlefield’s history. As the native vegetation is overwhelmed with non-native species, the increased amounts of animal species are lowering the unique biodiversity of the region, further decreased by habitat fragmentation and increased urban development. The greater system of habitats is important to the Palmito Battlefield site because many of the species present within the area cannot survive without such larger, intact habitat areas. This, therefore, would inhibit the ability for the site to look as it did in the 1865 battle, decreasing its historic integrity as a battlefield site.


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