A botanical inventory of Pecos National Historical Park, New Mexico

Submitted to: National Park Service, SW Regional Office, Santa Fe, NM

by Robert Sivinski, 1994

Listing of Plants in the Inventory by Family

"Non-techinal Report Summary:

The Pecos National Historical Park consists of 6,6671 acres of mostly pinion-juniper woodland in north-central New Mexico. Small areas of grassland, mixed conifer forest and riparian-wetland plant communities are also present on the Park. A botanical survey during 1993 and 1994 field seasons documented 354 vascular pant taxa within the Park. The Park is a botanically diverse area containing approximately 9% of the estimated 4,000 plant taxa known to occur in the entire State of ne Mexico. Alien (non-indigenous or exotic) species contribute heavily to this diversity since 16% of the Park flora is not native to New Mexico.

The potential habitats of seven rare or endangered plants species were searched during the survey. Only one sensitive species was found on the Park. One individual of dwarf milkweed, (Asclepias uncialis) was located near the town of Pecos at the north end of the Pecos Unit. This species is a C2 candidate for federal protection under the Endangered Species Act. It is widespread from Wyoming through eastern Colorado to southern New Mexico and southeastern Arizona. But it is not extremely rare and occurs in small populations. The single individual found on the Park did not produce fruit in 1994. This indicates a solitary, outcrossing plant with no pollen source in the area. This plant also occurs in the track of a seldom used road, which also indicates a habitat preference for slightly disturbed soil. The Pecos groundcherry (Physalis virginiana var campaniforma) is a rare New Mexico endemic that may occur along the creek at the Glorieta Battlefield. A single individual of the species was located there, but its varietal identity could not be determined because of its late phenological stage. Searches for both of these, and the other rare plants not located in this survey, should be continued by Park personnel.

The vegetation character of the Park has been influenced by several human uses and impacts. These include agriculture, livestock grazing, sand and gravel mining, roads and other developments. These impacts have resulted in the establishment of many alien plant species. The most pervasive and persistent species were purposely introduced as forage (Kentucky bluegrass, alfalfa, and Russian wildrye). Two species of European weeds (Scotch thistle and scorzonera) were documented for the first time in New Mexico during the Park survey. Vegetation in the area has also become more woody because of livestock grazing and the elimination of wild fire. The pinion-juniper woodland has become more dense and has invaded deeper grassland soils that were naturally kept free of trees by periodic fires.

Alien weed management on the Park should concentrate on minimizing soil disturbance and reclaiming disturbed areas with native, perennial species. Reversing the trend of grassland conversion to pinion-juniper woodland will require periodic tree removal from selected deep soil areas either by hand or with prescribed burns. The riparian woodland along the Pecos River is a significant wildlife habitat and relatively rare plant association. It is, however, a resilient community that can withstand moderate levels of Park use and visitation. Managing beaver predation on larger trees may be necessary to maintain the existing cottonwood bosque."