Non-native plants of Organ Pipe Cactus National Monument, Arizona
Felger RS. 1990. Non-native plants of Organ Pipe Cactus National Monument, Arizona. Technical Report No. 31. Cooperative National Park Resources Studies Unit-University of Arizona, National Park Service. Tucson, AZ
The vascular (or seed) plant flora of Organ Pipe Cactus National Monument (ORPI) contains remarkably few species of non-native plants. A low percentage of non-native, introduced, or "exotic" plants indicates the habitat is relatively "natural," and as such can be used as an index of the condition of the vegetation. The present report includes 64 species possibly non-native to ORPI which have been documented from the monument or adjacent regions and. potentially present or invasive into the monument. In addition, a few species previously thought to be present and non-native to ORPI were found to be either native or possibly native or not present. Bowers (1980) reported 522 taxa of vascular plants for ORPI, or about 518 species, of which about 5% were reported as introduced. Since then a few species listed by Bowers for ORPI are now known not to be present and additional species have been added to bring the total estimated flora to about 550 species (Pinkava et al., in prep.). The 64 species of potential non-natives is 11.6% of the total flora, but this is too high and misleading for a number of reasons. Some supposedly non-natives actually might be native, a few are present but not reproducing, and a number of them are present in adjacent Sonora but have not been documented for ORPI. Most significantly, a number of non-native species are not expected to persist in ORPI without continued immigration from adjacent disturbed habitats in Sonora. A non-native flora falling between 5% and 10% of the total flora speaks of a very healthy habitat, one indeed rare at the end of the 20th century. Comparisons with other floras are given below in Table 1. Two categories of non-native species should be distinguished. Colonizing species are non-native plants invading and establishing on disturbed habitats. Invading species are those establishing among natural, non-disturbed habitats (Mooney and Drake 1986).
- Type
- Published Report
- Authors
- Felger, Richard
- Date of Issue
- 1990-04
- Publisher
- Cooperative National Park Resources Studies Unit-University of Arizona, National Park Service
- Units
- ORPI , WRD
- Keywords
- Checklist, Distribution, Grasses (Gramineae), Natural Resource Management, Non-Native Species, Plants, Riparian Zone, Vascular Plants, WRBIB