Urban growth threatens newly discovered manzanita species

Deep in the Golden State, a new manzanita shrub species has been discovered, but its survival already teeters on the brink – threatened by the relentless spread of urbanization.

The manzanita, a shining symbol of California’s diverse flora, is known for its twisted branches and the incredible resilience it shows in the face of wildfire challenges.

With more than 60 species native to the state, this group of shrubs and small trees plays a crucial role in local ecosystems, providing food and shelter for wildlife. 

Nipomo Mesa’s native treasure

Researchers have now identified a new species of manzanita to add to the iconic collection. Discovered along the central coast, it has been named Arctostaphylos nipumu to recognize the Nipomo Mesa, where it was found, and to honor its Indigenous heritage.

Amy Litt, a plant biologist at the University of California Riverside, expressed her surprise at finding a new species in a highly urbanized district.

“We weren’t expecting to find a new species in such a developed area. But as we examined the plants, we realized the Nipomo Mesa plants were quite distinct. We were subsequently able to show that they not only look different but are genetically unique,” noted Litt.

This manzanita species sports a distinct, shaggy grey bark, which differentiates it from the emblematic red bark found on most of its Californian relatives.

Unique adaptations of manzanitas

Manzanita species are not just visually striking but also ecologically specialized, with remarkable adaptations that help them thrive in California’s harsh, fire-prone climate.

Their waxy, evergreen leaves minimize water loss, while deep roots tap into underground moisture reserves, which allows them to endure prolonged droughts.

Unlike most chaparral plants, manzanitas don’t resprout following a fire. Instead, their hard-shelled seeds require intense heat or smoke exposure to break dormancy and germinate, ensuring their regeneration in fire-swept landscapes.

Beyond their resilience, manzanitas serve as ecological keystones, offering nectar-rich flowers to pollinators like bees and hummingbirds, while their nutrient-dense berries sustain a variety of other birds and mammals.

Ecological significance of manzanitas

Manzanitas contribute to the biodiversity of California and play a crucial part in native ecosystems as sources of food and habitat for wildlife.

The historical value of manzanitas is entrenched in Indigenous tribal culture. Their berries are a source of food, their leaves are harvested for medicine, and their wood provides material for tools and firewood.

The recently discovered A. nipumu is no exception, and adds to the rich and iconic floral legacy of the state.

New manzanita will fight for survival

However, the survival of this manzanita species is already under threat due to the impending urban development unleashed by the Dana Reserve Project.

This recently approved housing development could potentially destroy much of the habitat where this species is located – threatening half of this plant’s fragile population.

Researchers, including plant geneticist and study co-author Bill Waycott, have alerted local officials to the potential ecological repercussions of the development plans.

The discovery of A. nipumu has prompted environmental organizations such as the California Native Plant Society to emphasize the ecological significance of the Nipomo Mesa.

These concerns are further amplified by the fact that, like many manzanitas, A. nipumu relies on fire for seed germination. However, its inability to resprout after wildfires due to the lack of a protective burl makes it especially vulnerable.

Habitat restoration and genetic diversity

Tito Abbo, co-author of the study and graduate student in the Litt lab, pointed out the difficulties associated with restoring habitats.

Abbo explained that the reintroduction of native species is often facilitated using nursery stock that does not have the same genetic diversity as the wild relatives. Such plants are more vulnerable to disease and environmental stress.

“When you propagate from just a few individuals, you have a limited pool of genetic diversity and potentially less variation in natural plant defenses,” explained Abbo.

With the looming threat of urban expansion, unique habitats like the Nipomo Mesa are faced with destruction. Once their habitats are lost, they are near impossible to restore fully.

The future of A. nipumu remains uncertain, but its official recognition marks a crucial first step, paving the way for essential discussions and efforts toward its preservation.

The full study was published in the journal PhytoKeys.

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