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Abstract Detail

Floristics & Taxonomy

Donovan, Daniel [1], Fisher, Amanda [2].

Vascular Flora of Ladd Canyon, Santa Ana Mountains, California.

The California Floristic Province, one of the world’s five regions with a Mediterranean-type climate, is a global diversity hotspot. In southern California, the Santa Ana Mountains are a coastal range between Orange and Riverside counties, and they have been well-explored by botanists. Even so, there have been few in-depth floristic surveys since Lathrop & Thorne’s (1978) preliminary study of the mountain range and collecting has mainly occurred along roads and trails. Ladd Canyon (approximately 1,750 ha.) is an intriguing target for study because it has relatively few access routes and has not been surveyed in depth. Several physical features make it stand out as well. The divide to the north has the only serpentine soil in the Santa Ana Mountains, which has been credited for the presence of several stands of knobcone pine (Pinus attenuata). Additionally, the topography of the range funnels wet marine air up through Ladd Canyon and increases fog drip. The area has also burned less frequently than most of the mountain range. Communities include pine stands at higher elevations, riparian woodlands, chaparral, and coastal sage scrub. My preliminary surveys of the study area have yielded five rare taxa: Lepechinia cardiophylla (California Rare Plant Rank 1B.2), Calochortus weedii var. intermedius (1B.2), Lilium humboldtii ssp. ocellatum (4.2), Romneya coulteri (4.2.), and Polygala cornuta var. fishiae (4.3), with significant populations of all except Calochortus weedii var. intermedius. Healthy Pinus attenuata stands are found on steep slopes and along ridges, in some cases surrounding apparent serpentine barrens, and Pinus coulteri stands dot the upper divide. The three forks of the canyon hold a variety of tree species: Pseudotsuga macrocarpa, Quercus chrysolepis, Q. wislizenii, and Q. agrifolia, Acer macrophyllum, Umbellularia californica, Fraxinus dipetala, Alnus rhombifolia, and Platanus racemosa. High elevation chaparral includes Ceanothus papillosus, found in only a few other areas of the mountains. I will collect voucher specimens to document the flora and consult the few specimens by other collectors to build a checklist in the Consortium of California Herbaria 2 and an iNaturalist project for the area. Floristic studies such as this provide a baseline of data in the face of climate change and human disturbance and add to science by extending species distributions and uncovering new species. In addition, the flora will help to inform the Cleveland National Forest’s management of rare and invasive species in the area.

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1 - 374 Mira Mar Ave., Long Beach, CA, 90814, United States
2 - California State University, Long Beach, Biological Sciences, Mail Stop 9502, 1250 Bellflower Blvd, Long Beach, CA, 90840, United States

Santa Ana Mountains
Cleveland National Forest
Ladd Canyon.

Presentation Type: Poster
Session: P2, Floristics & Taxonomy Posters
Location: Virtual/Virtual
Date: Tuesday, July 20th, 2021
Time: 5:00 PM(EDT)
Number: P2FT015
Abstract ID:1063
Candidate for Awards:None

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