The SRER Repeat Photography collection provides a long-term, landscape-scale representation of vegetation dynamics over 122 years, incorporating century, decadal, and annual time scales across 119 locations spanning 20,000 ha. Since 2000, photographs have been taken approximately every six years, primarily in March (114 locations) or October (5 locations). Most older repeat photographs span 15 to 20 years and were taken in different months to meet specific research needs. Photographs were repeated in consecutive years to document annual vegetation changes at only 15 locations between 1950 and 1960.
SRER Ecological Sites and August Photo Stations (In black, PS established in 2024).
In August 2024, we decided to re-establish annual repeat photography on the SRER in an effort to:
- Document and better understand vegetation and species richness annual changes after each monsoon season;
- Contribute to updating the Flora of the SRER;
- Inform the annual livestock grazing plan.
We selected 18 Photo Stations (PS), 14 existing and 4 established in 2024, for a total of 23 Photo Directions:
- Distributed on the SRER from 920 to 1,430 m in elevation ascending to SE;
- Representing different Ecological Sites;
- With open views on Desert Grasslands, a mixture of short trees, shrubs, cacti and other succulents, perennial grasses, and other herbaceous species.
At each location, we decided to record all annual and perennial plant species within a 40 m² area in front of the camera aiming to document changes in vegetation and plant species richness. Floristic plots were set to start 2 m from the camera and end 8 m from camera, with right and left boundaries following the right and left edges of the camera view.
Seventy-three plant species were recorded in August 2024, averaging 13 species per location. Most species were perennial (64%). The most represented families were Asteraceae (19%), Poaceae (16%), and Euphorbiaceae (11%). Eragrostis lehmanniana, Digitaria californica, Machaeranthera tagetina, and Panicum hirticaule were found at over 50% of the photo directions. Three species, Encelia frutescens, Euphorbia polycarpa, and Euphorbia serpillifolia, were not previously listed in the SRER Flora (Medina, 2003) or documented for the SRER in the SEINet portal (https://swbiodiversity.org/seinet/; September 2024). Their specimens have been or will be deposited at The University of Arizona Herbarium for future reference.
A comprehensive list of plant species recorded at the August Photo Stations can be found on the Flora page.
To learn more about the 2024 August Repeat Photography, download below the poster presented at the 2024 RISE Symposium: Species Richness During the 2024 Effort to Start Repeat Photography in August on the Santa Rita Experimental Range.
References
Medina, Alvin L. 2003. Historical and Recent Flora of the Santa Rita Experimental Range. In: McClaran, Mitchel P.; Ffolliott, Peter F.; Edminster, Carleton B., tech. coords. Santa Rita Experimental Range: 100 years (1903 to 2003) of accomplishments and contributions; conference proceedings; 2003 October 30–November 1; Tucson, AZ. Proc. RMRS-P-30. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 157-165.
SEINet Portal 2024. https://swbiodiversity.org/seinet/