Riparian areas – the land adjacent to a river, creek or stream – are unique and important habitats. Because of their low elevation and proximity to waterways, they’re subject to frequent (and often extended) floods. Additionally, this proximity to water increases the number of insects and fungi living in these areas.
The species that dominate riparian areas – including everything from muskrats and water snakes to mosses and ironwoods – often exhibit adaptations that help them survive in these habitats. For example, the animals living in this zone are often skilled at collecting food from the nearby water in order to exploit the resource, while many of the plants have developed the ability to live in poorly drained soils.
Below, we’ll examine four of the best California natives for riparian areas. But, understand that these tree species will often work in other wet areas too. Try them in your raingarden or along the border of a farm pond. They will often thrive in these habitats as well.
California sycamores (Platanus racemosa) are the titans of the riparian area – they not only reach large sizes (sometimes exceeding 80 feet in height), but they do so quickly, thanks to their growth rate, which can approach 3 feet per season. Sycamores frequently play the role of pioneer, given their rapid growth rate and appreciation of full sun exposure.
Sycamores have some of the most attractive trunks of California’s native trees. They are often light-tan to white in color, with multi-colored patches of brown, red or gray bark over the light-colored trunk wood.
One of the best trees for California properties, western redbuds (Cercis occidentalis) are gorgeous trees that offer visual interest throughout most of the year. Their purple to pink flowers are some of the first to blossom in the early spring, and they are followed by charming, heart-shaped leaves in the summer, before shedding their leaves to show off their hanging seed pods, which will last well into the cool months.
Redbuds are often capable of surviving extended, even periodic, flooding. However, they often go semi-dormant and cease root production during inundated periods.
Also known as the horse chestnut, the California buckeye (Aesculus californica) is an attractive, hardy tree that can survive in a number of different Californian ecosystems. Somewhat famous for their deadly fruit, horse chestnuts are actually toxic to a number of animals, including non-native bees and many other would-be pollinators.
California buckeyes have evolved an unusual timing to help thrive in California’s Mediterranean climate. For example, rather than leafing out in April or May, these 5-foot-tall trees often begin producing leaves in early February. Similarly, they may shed their leaves earlier in the summer than many others do – particularly if they are not provided with sufficient water.
California Bay Laurel
The California bay laurel (Umbellularia californica) is perhaps best known for its aromatic leaves, which smell like fresh pepper when crushed and have been used for centuries as a spice to flavor food. But that’s not the only thing these leaves are good for: People have long used them as a treatment for lice, fleas and other biting insects.
While bay laurels often grow in dense, shrub-like hedges, they also grow as proper trees, and occasionally reach 80 feet in height. This is most common in riparian areas or other places with adequate soil moisture, so be sure you understand the potential of these hardy trees before installing them on your property.
Found throughout much of California and extending into Oregon, Washington and Idaho, the white alder (Alnus rhombifolia) is a common sight near low-lying, wet areas. A nitrogen-fixing species, white alders help to support the other plants living near them, by increasing the amount of nitrogen in the soil.
Alders are somewhat unique-looking in that their female catkins (flowers) often resemble miniature pine cones. The resulting seeds are spread via wind, seed-eating birds and water. This often results in the total colonization of riparian areas, creating a continuous canopy of these attractive trees.
If you’d like help selecting or installing trees for your streamside property or raingarden, give your friends at Evergreen Arborist Consultants a call. We can help you select and install the best trees for your property.