What is the Chaparral Biome?

You’ve driven through it, perhaps even hiked a trail, and might have even gotten chapped lips from the dry heat – but there’s more to it than most of us realize. Meet the chaparral biome – the primary biome found in Southern California, known for its hot, arid summers and cooler, rainy winters (Barro & Conard, 1990, p. 135). Although this biome only covers about 2.5% of the world’s surface, including California, Central Chile, South Africa, Southwestern Australia, and the Mediterranean basin (California Chaparral Institute, n.d.), it is home to 16% of the world’s plant species (Halsey & Keely, 2013).

Chaparral in Newport Beach. Photo Credit: OC Habitats.

In California, the chaparral spans across “the inland foothills and mid-level mountain slopes of the Peninsular, Transverse, and Coast Ranges” and “the foothills of the Sierra Nevada, the Klamaths, and the Cascade Mountains” (Cal Geographic, 2022). California’s chaparral stands out among regions for its unique qualities: a biodiversity hotspot that supports abundant wildlife and is home to many endemic and rare plant species (Halsey & Keely, 2013). In fact, on a per-area basis, California supports roughly seven times as many species as any other region in the United States, and much of this biodiversity is concentrated in chaparral ecosystems (Halsey & Keely, 2013).

Plants in the chaparral have many adaptations that help them withstand the dry, arid Mediterranean climate. Plants use a process called transpiration to pull water from the soil to their leaves, where it is used for photosynthesis, a process in which plants create their own food in the form of sugars. However, in dry, arid regions such as the chaparral, significant amounts of water can be lost through transpiration. To reduce this water loss, chaparral plants have a specialized adaptation: sclerophyllous leaves, which are hard, waxy, and inedible (Nelson, 2013). This waxy outer layer functions as a seal, preventing water inside the plant from evaporating through transpiration loss and keeping it within the plant to conserve water for photosynthesis (Environmental Nature Center, 2020). Plants with this adaptation include coast live oak (Quercus agrifolia) and manzanita (Arctostaphylos manzanita).

From left to right: coast live oak (Quercus agrifolia), manzanita (Arctostaphylos manzanita). Their sclerophyllous leaves help them retain moisture for photosynthesis in arid environments. Photo Credit: OC Habitats

To help themselves conserve energy, chaparral plants are deciduous. This adaptation means that they enter a time of dormancy, meaning entering a period of being inactive, to conserve energy. Chaparral plants enter this dormancy period when temperatures are extreme, such as during the cold winter months and the hot summer months. Since vegetation is experiencing heightened stress from these extreme temperatures, plants drop their leaves to conserve water and energy, helping them survive (National Park Service, 2024). These leaves also benefit the soil, as they decompose, making it nutrient-rich. Since the plants drop their leaves in the cold, rainy winter and hot, dry summer months, it does not mean that they are dead– they are very much alive to protect themselves from these extreme temperatures by conserving their energy and water.

Laurel sumac (Malosma laurina) has leaves with a crease in the middle that folds to help create shade and keep them cool. Photo Credit: OC Habitats.

Another drought-resistant adaptation of plants is the shape of their leaves. To help themselves stay cool in the dry heat, some plants fold like a taco shell to reduce the surface area exposed to sunlight, creating shade that helps them stay cool and limits water loss through evaporation. Plants like the laurel sumac (Malosma laurina) have this adaptation (Environmental Nature Center, 2020). Additionally, many chaparral plants, such as California sagebrush (Artemisia californica), have light-colored leaves which easily reflect sunlight to help them stay cool and prevent water loss, a process known as desiccation (Environmental Nature Center, 2020).

In addition to leaf adaptations, plant species have evolved root adaptations to withstand the dry conditions of the chaparral biome and to enhance water uptake. Due to the arid Mediterranean climate, there is little water available in the top layers of soil for plants to use in photosynthesis. Therefore, plants have evolved tap roots that reach deep into the ground to access water stored far below the surface (Guerrero-Campo et al., 2006). 

A closer look at tap and fibrous roots and how their root structures differ. Photo Credit: Vecteezy.com

Furthermore, vegetation in fire-prone areas, such as chamise (Adenostoma fasciculatum) and California scrub oak (Quercus berberidifolia), has evolved to allocate more of its reserves (stored energy and nutrients used for growth) to specialized deep root systems to improve water uptake (Guerrero-Campo et al., 2006). Additionally, some species have shallow, fibrous roots that spread laterally in the soil to increase their surface area and obtain water after minor rainfall (Guerrero-Campo et al., 2006). These wide and deep root systems give chaparral vegetation an advantage in regenerating after wildfires. With their adaptive root systems protected underground, they can regrow above ground quickly because the roots are already established. 

Chamise (Adenostoma fasciculatum) (left) and California scrub oak (Quercus berberidifolia) (right) have extensive root systems that anchor them in the soil, helping them rebound after wildfires. Photo Credit: OC Habitats

​Animals in chaparral ecosystems have evolved many adaptations to survive the hot, arid climate, drought conditions, and frequent wildfires. Many species are nocturnal, meaning they are awake at night and asleep during the day to avoid the dry heat, save energy, and stay cool. Some notable nocturnal animals include the gray fox (Urocyon cinereoargenteus) and the coyote (Canis latrans) (Frey, 2024). Additionally, smaller animals, such as the California ground squirrel (Otospermophilus beecheyi), dig burrows to stay cool in the dry heat and take shelter during fires (Bailey, 2018). Burrows dug by California ground squirrels can range from 5 to 30 feet (UC Statewide IPM Program, 2025)!

The coyote (Canis latrans) (left) and California ground squirrel (Otospermophilus beecheyi) (right) have unique adaptations to help themselves stay cool in the Chaparral’s dry environment. Coyote photo credit: Christina Butler. California ground squirrel photo credit: Holly Cheng

Reptiles of the chaparral also have special adaptations that help them withstand the dry, arid climate. The Coast Horned Lizard (Phrynosoma coronatum) found in the chaparral has scales made of keratin– the same protein that makes up our hair and nails– to provide protection from scrapes as they scurry over rocky surfaces. These scales also act as a layer of sunscreen, protecting their skin from damaging UV rays (Reptile Encounters, 2013) and help reptiles retain moisture within their bodies, keeping them cool. This makes them less likely to become dehydrated and allows them to survive on only small amounts of water (Papagiorgio, 2022).

​The scales of the Coast Horned Lizard (Phrynosoma coronatum) provide protection from UV rays and help them stay cool in their hot environments. Photo Credit: Bill Levine.

​While chaparral wildlife is adapted to tolerate extreme heat and dryness, the biome itself is also shaped by another powerful force: fire. Low-intensity fires are useful for clearing dead vegetation and decaying plant material from the ground, preventing them from becoming fuel for larger, catastrophic fires. Additionally, clearing dead vegetation allows soil organisms to access previously covered nutrients and enables the growth of emerging or smaller plants beneath this layer to flourish (National Geographic, 2025). After these low-intensity fires, nutrients from the ashes of dead vegetation enrich the soil, promoting new plant growth and allowing sunlight to reach the surface (Snow, 2022). 

These low-intensity wildfires that clear vegetation also benefit animals. Grazers like mule deer (Odocoileus hemionus) do not eat fallen leaves from trees, and since fires clear out dead leaves, they have better access to their preferred food sources that get overcrowded by dead vegetation. Additionally, with cleared ground, birds of prey can spot their prey more easily, making it easier for them to hunt and find food.

Mule deer (Odocoileus hemionus) benefit from low-intensity, natural fires, as they clear out dead vegetation that makes their food sources more accessible. Photo credit: Walter Siegmund.

Wildfires were once naturally recurring, occurring every 30-150 years (California Chaparral Institute, n.d.); however, human activities in recent decades have made them larger, more intense, and more frequent. In fact, a majority of fires are caused by human activities, such as carelessly discarded cigarettes, unattended campfires, vehicle-related incidents, arson, and burning debris (Western Fire Chiefs Association), and are no longer natural occurrences. With fires occurring more frequently, native vegetation does not have enough time to regenerate, threatening its biodiversity through irreversible losses of native plant communities and important habitats for native wildlife, and increasing the likelihood of invasive species spreading (California Department of Fish and Wildlife, n.d.). Invasive species are non-native plants or animals that cause environmental damage and threaten native wildlife, biodiversity, and the resources we depend on, such as food and water (US Forest Service, n.d.). 

Black mustard (Brassica nigra), despite its pretty appearance, is an invasive species that can fuel catastrophic fires, causing significant economic damage. Photo Credit: OC Habitats.

A notable invasive in California is black mustard (Brassica nigra). Despite its pretty yellow flowers that cover hillsides, black mustard poses a catastrophic risk to local areas. When black mustard dies, dried branches can fuel large, disastrous fires. Large wildfires also disrupt ecosystems’ capacity to regenerate. As a result, past naturally occurring fire patterns have been altered, thus “producing an imbalance between wildfire and ecosystem interactions” (California Department of Fish and Wildlife, n.d.).

So next time you're driving by sunbaked foothills or hiking through dense shrubs, take a moment to notice and observe the chaparral biome around you. What appears to be a dry, arid landscape is actually a balanced ecosystem where plants and wildlife have many adaptations to the dry climate while also relying on the ecological benefits of natural fires. However, as human-caused fires become more frequent and intense, this natural balance is increasingly threatened, putting the native wildlife and vegetation of Southern California's chaparral at risk. OC Habitats works to restore ecosystems within the chaparral biome by restoring native plant communities, removing invasive species, and providing educational opportunities (e.g., guided hikes) for our community to learn about our local environment and its value. We host many restoration and educational events throughout the year and welcome volunteers, so please sign up to join us in preserving and learning more about the chaparral biome!

References

Bailey, R. (2018). Land Biomes: Chaparrals. ThoughtCo. https://www.thoughtco.com/land-biomes-chaparrals-373500#:~:text=Wildlife,order%20to%20reduce%20water%20loss. 

Barro, S. C., Conard, S. G. (1990). Fire effects on California chaparral systems: an overview. Environment International(17), pp. 135–149. https://doi.org/10.1016/0160-4120(91)90096–9. 

Cal Geographic. (2022). The Chaparral Mosaic in California. https://calgeographic.com/2022/12/05/biogeography-chaparral-mosaic/ 

California Chaparral Institute. (n.d.). Chaparral. https://www.californiachaparral.org/chaparral/ 

California Chaparral Institute. (n.d.). Chaparral Fire Ecology. https://www.californiachaparral.org/fire/chaparral-fire-ecology/ 

California Department of Fish and Wildlife. (n.d.). Science: Wildfire Impacts. https://wildlife.ca.gov/Science-Institute/Wildfire-Impacts 

Environmental Nature Center. (2020). Chaparral Plant Adaptations [video]. YouTube. https://www.youtube.com/watch?v=9KJMGR_WFSA 

Frey, E. (2024). Coyote Adaptations From Desert to Urban Areas. The Rogue Scholar. https://rogue-scholar.org/records/yma8k-9vf29#:~:text=To%20survive%20in%20these%20harsh,survival%20in%20these%20challenging%20environments. 

Guerrero-Campo, J., Palacio,  S., Pérez-Rontomé, C., Montserrat-Martí, G. (2006). Effect of Root System Morphology on Root Sprouting and Shoot-Rooting Abilities in 123 Plant Species from Eroded Lands in North-east Spain. Annals of Botany(98). 439–447. 10.1093/aob/mcl122

Halsey, R. W., & Keeley, J. E. (2013). Conservation Issues: California Chaparral. In Reference Module in Earth Systems and Environmental Sciences. Elsevier Inc. https://doi.org/10.1016/B978-0-12-409548-9.09584-1 

National Geographic. (2025). The Ecological Benefits of Fire. https://education.nationalgeographic.org/resource/ecological-benefits-fire/ 

National Park Service. (2024). Plant Communities. https://www.nps.gov/cabr/learn/nature/plant-communities.htm?utm_source=chatgpt.com 

Nelson, R. (2013). Chaparral Biome. Untamed Science. https://untamedscience.com/biology/biomes/chaparral-biome/#:~:text=Another%20adaptation%20that%20many%20of,water%20during%20the%20summer%20drought 

Papagiorgio, N. (2022). What Is The Function Of Scales On Reptiles? Sciencing. https://www.sciencing.com/function-scales-reptiles-6610193/ 

Reptile Encounters. (2013). Why Do Reptiles Have Scales? https://www.reptileencounters.com.au/news/why-do-reptiles-have-scales#:~:text=For%20example%2C%20in%20contrast%20to,which%20helps%20them%20stay%20healthy. 

Snow, M. (2022). How Does Wildfire Impact Wildlife and Forests? U.S. Fish & Wildlife Service. https://www.fws.gov/story/2022-10/how-does-wildfire-impact-wildlife-and-forests#:~:text=After%20low%2Dintensity%20fires%2C%20grasses,back%20down%2C%E2%80%9D%20said%20Kelly 

UC Statewide IPM Program. (2025). Ground Squirrel. https://ipm.ucanr.edu/home-and-landscape/ground-squirrel/#gsc.tab=0 

US Forest Service. (n.d.). Invasive Species. https://www.fs.usda.gov/managing-land/invasive-species#:~:text=Invasive%20species%20have%20two%20main,Native%20Pests%20and%20Diseases 

Western Fire Chiefs Association. (2024).Wildfire Causes. https://wfca.com/wildfire-articles/what-causes-wildfires/