Demographic Characteristics of 3 Artemisia tridentata Nutt. Subspecies
Perryman BL, Maier AM, Hild AL, Olson RA. 2001. Demographic Characteristics of 3 Artemisia tridentata Nutt. Subspecies. Journal of Range Management. 54(2):166-170
Previous research suggested that woody plant recruitment may occur in pulses on semi-arid areas. The overall objective of this study was to determine if this pulse phenomena was recorded in the demographic structures of big sagebrush (Artemisia tridentata Nutt.) stands in Wyoming. In 1997, approximately 75 stem cross sections were collected from 9 stands of each of 3 subspecies of big sagebrush in Wyoming along elevation and climatic gradients. Annual growth-rings were used to identify year of establishment and demographic characteristics were analyzed from age-class frequencies. Mean stand ages of the 3 subspecies were different (P=0.002), and analyses revealed that Wyoming (A. tridentata spp. wyomingensis) and mountain big sagebrush (A. tridentata spp. vaseyana) stand ages (32 b 9 and 26 b 9 years, respectively) were significantly older than basin big sagebrush (A. tridentata spp. tridentata) (17 b 3) stands (P < 0.05). Mean recruitment intervals (years) were shorter for basin (1.6) than for Wyoming (2.3) and mountain (2.2) sagebrush (P=0.01). The number of cohorts did not differ among the subspecies (P=0.11), but the percent of years with recruitment was significantly higher for basin (59%) compared to Wyoming (37%) and mountain (39%) subspecies (P<0.0001). Age-class frequency distributions of each stand and regional stand combination were assessed for dispersion across each associated period of record. Chi-square goodness-of-fit tests were performed for the negative binomial distribution. All stands (with one exception) and all 3 regional stand combinations fir the negative binomial distribution. Age-class frequency patterns indicate that recruitment is clustered or aggregated across each period of record. Recruitment in big sagebrush stands occurs in pulses throughout Wyoming. (Abstract by Perryman et al as printed in Journal of Range Management).
- Type
- Journal Article
- Authors
- Perryman, Barry; Maier, Aaron; Hild, Ann; Olson, Richard
- Units
- BICA , GRTE , YELL
- Keywords
- Ecology, Inventory and Monitoring (I&M), Plant Communities, Plant Studies, Range Management, Rangeland