The biotic provinces of Texas.

Abstract

The major biotas are represented in Texas. Plants and animals of the eastern, humid, coastal plain forest that enter eastern Texas. Plants and animals of the arid southwestern deserts and mountains are characteristic of Trans-Pecos Texas. Various species of Neotropical plants and animals that enter southern Texas on the Rio Grande plain. These biotas interdigitate and intermix in characteristic combinations throughout much of the area of Texas. Seven biotic provinces are recognized within the borders of Texas, but no one of these is completely limited to the state. Austroriparian province extends into eastern Texas and occupies a strip of coastal plain from the Gulf of Mexico to the Ouachita Mountains of Oklahoma. The plants and animals of this province are mostly species that extend eastward on the coastal plain to the Atlantic. The Texas province, bordering the Austroriparian in eastern Texas, is a broad ecotone between the Austroriparian forest and the semiarid grasslands to the west. It is characterized by the interdigitation of forest and grassland associations and species. The Tamaulipan province includes the Gulf coastal plain south of the Balcones Escarpment and west of the boundary between pedalfer and pedocal soils. This province is characterized by an intermixture of Neotropical species, Austroriparian species and southwestern desert species. The Chihuahuan province includes all of Trans-Pecos Texas except the Guadalupe Mountains. The plants and animals of this province are mostly species that are widely distributed in the mountains and deserts of southwestern North America. The Navahonian province, which includes a large part of New Mexico, extends into Texas in the Guadalupe Mountains. The fauna shows close relationship to the fauna of the Chihuahuan province, but several high-elevation species occur in the Navahonian and fail to reach the Chihuahuan. The Kansan province takes in the Panhandle and the red plains to the east of the escarpment of the high plains. The plants and animals are mostly grassland species but some Austroriparian species extend along wooded stream valleys into the eastern part of the province. The Balconian province includes the Edwards Plateau, the Lampasas Cut Plain, and the Central Mineral Region. This is a region of intermediate ecological conditions between the eastern forest and the western deserts. The fauna is a mixture of Austroriparian, Tamaulipan, Chihuahuan and Kansan province species. There is an endemic urodele fauna of five known species.