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PLANT DIVERSITY AND ENDEMISM IN THE CALIFORNIA FLORISTIC PROVINCE

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Abstract

The California Floristic Province (CFP) is an area of high biodiversity and endemism corresponding roughly to the portion of western North America having a Mediterranean-type climate. High levels of diversity and endemism in the CFP are attributed to the unique geo-climatic setting of the region. In recent years, much has been learned about the origins of plant diversity in western North America. This work, however, has been hindered by a focus on political rather than biotic regions, such that much more is known about diversity and endemism in the state of California than the natural biotic region represented by the CFP. Here we present a preliminary list of native land plants (vascular plants and bryophytes) found in the CFP, as well as an analysis of diversity and endemism patterns at the level of both species and minimum rank taxa (MRT; species and infraspecific taxa). A total of 6,927 MRT are native to the CFP, including 6,143 vascular plants and 784 bryophytes. Of these, 2,612 vascular plants are endemic to the CFP (42%) compared to 37 endemic bryophytes (5%). Finally, 2,506 native CFP vascular plant MRT (41% of the CFP flora) and 454 CFP bryophyte MRT (58% of the CFP flora) are found outside California in the Oregon and Baja California parts of the CFP. This high degree of sharing across political boundaries among both vascular plants and bryophytes highlights the cohesiveness of the CFP, and the need to focus more research effort on biotic regions.
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... Floristic provinces are defined by phytogeographic and climatic factors (Raven and Axelrod 1978;Burge et al. 2016). At the broadest level, the study area is contained within the CFP (Jepson Flora Project, 2022). ...
... At the broadest level, the study area is contained within the CFP (Jepson Flora Project, 2022). The CFP is located along the Pacific coast of western North America and is characterized by a Mediterranean climate and relatively high rates of species richness and endemism (Burge et al. 2016;Stebbins and Major 1965;Raven and Axelrod 1978), so much so that it has been designated as a global biodiversity hotspot (Myers 1990 (Meyer 1978). Plant distributions are likely to change in conjunction with the current changing climate regime. ...
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The Manter and Salmon Creek watersheds occur in the southern Sierra Nevada, Tulare County, CA. The study area encompasses 132 sq. km. (51 sq. mi.) on the Kern Plateau. There are several aspects of this region that make it worthy of botanical exploration, including the presence of numerous endemic (e.g., Pinus balfouriana subsp. austrina, Eriogonum polypodum) and rare taxa (e.g., Eriogonum breedlovei var. shevockii, Carlquistia muirii). In addition, the Domeland Wilderness, which makes up 65 sq. km. (25 sq. mi.) or ca. 50% of the study area, has had little formal documentation of plant diversity. Documenting this diversity in the present time is vital because there are several impacts to the flora from land use and climate change. Cattle grazing, off highway vehicle use, logging, long-term drought, and the impacts from a changing fire regime were all documented at the area. These disturbances may have a lasting impact on the flora. As a part of this study, I completed a total of 24 field trips, totaling 86 field days, that resulted in the collection of 1,412 plant specimens. A total of 590 minimum-rank taxa were documented in the study area, representing 78 families and 270 genera. Of the minimum-ranked taxa, 34 are non-native and 28 have conservation status. Angelica callii, a California endemic with a California Rare Plant Ranking of 4.3, was newly documented in the study area, representing an eastward range extension of 26 km (16 mi). The results include a complete description of vegetation and habitats, as well as an annotated checklist with descriptions of local abundance, habitat types, and a voucher citation for each taxon documented.
... About 70 % of California is within the California floristic province, one of 36 global biodiversity hotspots sensu Myers 2000 and the only hotspot in North America (Myers et al., 2000). This province supports several different ecosystem types and exhibits a high degree of plant endemism (Burge et al., 2016). It is important, therefore, to assess the potential impact of air pollution within the region. ...
... California has a high degree of plant endemism. It is estimated that 42 % of vascular plant species native to the California Floristic Province (which covers most of California, though also extends a bit into surrounding states) are endemics (Burge et al., 2016), and stresses from ozone exposure are a likely conservation concern for rare plants. Recent studies have also found ozone exposures with high potential for negative ozone impacts on vegetation in California (Bytnerowicz et al., 2019;Yates et al., 2020). ...
Article
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... One particular form of semiarid vegetation, coastal sage scrub (CSS), is characteristic of the lowland and middle elevations of the coastal Pacific Mediterranean Climate Zone that encompasses the southern portions of California and northwest Baja California [8,9]. The CSS ecosystem is a biodiversity hotspot that supports high plant species richness and endemism [10,11], including at least 60 plants and thirty animal taxa considered rare [12]. ...
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Increasing urbanization on the Baja California Peninsula threatens ant diversity. Reductions in ant species diminish ecosystem services provided to semiarid coastal scrub areas. Peri-urban areas in particular are at high risk of reductions in ant biodiversity due to development. To document and evaluate ant species diversity and richness in a rapidly developing area, nine sites were sampled within areas of coastal sage scrub (CSS) encircling the urban periphery of Ensenada, Baja California. Forty species and 17 genera of ants were collected, only one of which was non-native. Although the sampled area represents less than 1% of the peninsula and 3% of the State of Baja California, approximately one-third of the total species recorded for the peninsula and state were collected. Environmental variables (compass orientation, slope, and vegetation cover) were not significant determinants of species richness. Sandy soils were associated with the highest species abundance, richness, and functional diversity of feeding guilds. Despite limitations, our results present a historically significant snapshot of ant diversity in the sage scrub areas surrounding Ensenada. Sandy regions of semiarid coastal scrub are prime conservation management areas as they support the greatest functional diversity and have the highest potential to supply environmental services to the surrounding CSS ecosystem.
... Like other regions of the world (Bowman et al., 2020), California and the western United States generally have experienced their largest and most severe fires in the last 20 years (Li & Banerjee, 2021). With a wide range of ecosystems (Burge et al., 2016;Harrison, 2013), California presents an important opportunity to understand the impacts of megafire on diverse ecological communities and to observe how patterns of species vulnerability or resilience may interact with these perturbations. ...
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... 7, 9, and 26) and the evolutionary origins of CFP biodiversity (8,22,27) and community assembly dynamics (7,9). The CFP hot spot is characterized largely by a Mediterranean climate and includes a range of biotic subregions that together support nearly 7,000 native species or subspecies of plants (28). Vegetation types within the CFP are a mosaic of ecosystems ranging from serpentine chaparral to coniferous forests and exhibit high spatial variation distributed across a topographically diverse landscape (26). ...
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