Ten-Year Resurvey of Epidermal Browning and Population Structure of Saguaro Cactus (Carnegiea gigantea) in Saguaro National Park
Turner DS and Funicelli CS. 2000. Ten-Year Resurvey of Epidermal Browning and Population Structure of Saguaro Cactus (Carnegiea gigantea) in Saguaro National Park. United States Geological Survey Western Ecological Research Center Sonoran Desert Field Station and School of Renewable Natural Resources
This project at Saguaro National Park investigated the health and demography of the park's most conspicuous resource, the saguaro cactus (Carnegiea gigantea). An extensive monitoring study was conducted on the size structure and health of saguaro populations in both park districts, (Rincon Mountain District and Tucson Mountain District) which are separated by the rapidly growing city of Tucson. Of particular interest was the phenomenon of epidermal browning and its relationship to saguaro health. The causes of this condition are poorly understood, and this study documents its extent and effects on saguaro populations. The results of this study confirm that epidermal browning is a progressive condition in individual plants. This study was the park's first opportunity to revisit plants studied 10 years prior, and to analyze changes in epidermal browning over that time. It also represents an extensive effort to identify trends in saguaro demographics, critical information as the park continues to recover from historic damaging influences such as grazing, mining, and wood harvesting. Together, these studies may provide useful baseline data for identifying impacts from current influences such as air pollution, urban encroachment, increased visitation, and exotic species invasion. The entwined correlations between height, browning, and mortality make it difficult to separate browning as a cause or indicator of death in saguaros. Further research will be required to determine if the condition of epidermal browning or the factors which contribute to it actually lead to premature death in saguaros, or if browning and mortality are results of a natural aging process.
- Type
- Resource Guide
- Authors
- Turner, Dale; Funicelli, Carrieanne
- Date of Issue
- 2000-10
- Publisher
- United States Geological Survey Western Ecological Research Center Sonoran Desert Field Station and School of Renewable Natural Resources
- Units
- SAGU
- Keywords
- cavities, epidermal browning, long-term studies, population density, saguaro
- Subjects
- Ecological Framework: Biological Integrity | Infestations and Disease | Plant Diseases , Ecological Framework: Biological Integrity | Focal Species or Communities | Desert Communities , Ecological Framework: Biological Integrity | Focal Species or Communities | Vegetation Complex , NPS.gov Subject Site: Deserts , NPS.gov Subject Site: Diseases & Pests , NPS.gov Subject Site: Park Science , NPS.gov Subject Site: Science of the American Southwest