In Jurupa Valley, California, a Palmer’s oak tree estimated to be at least 13,000 years old has been the source of conflict at the intersection of development and environmental responsibility. FCS assisted in finding a suitable compromise that protects both the tree and the project.
In the City of Jurupa Valley in Southern California’s Inland Empire, the Rio Vista Specific Plan, a mixed-use development project proposed by Richland Communities, threatens a very unique biological and cultural resource – the ‘Jurupa Oak’ or, as it is known by the Gabrieleño Band of Mission Indians-Kizh Nation, the ‘Hurungna Oak.’ The Hurungna Oak is a Palmer’s oak (Quercus palmeri), a species native to California, Baja California, New Mexico, and Arizona. Palmer’s oaks are not a rare or endangered species, but what makes the Hurungna Oak so special is that it is estimated to be between 13,000 and 18,000 years old, making it the third oldest organism on Earth. Due to its age and proximity to important prehistoric cultural sites, the Kizh Nation successfully petitioned the California Native American Heritage Commission to list the Hurungna Oak on its Sacred Lands Inventory in 2018.
The County of Riverside originally approved the 900+ acre Rio Vista Specific Plan in 1992, as it was located in unincorporated Riverside County at the time. The City of Jurupa Valley was incorporated in 2011, and the Rio Vista Specific Plan area was included within the City’s boundaries. The City pursued an updated Rio Vista Specific Plan with the publication of an Environmental Impact Report (EIR) in 2023. Project developers and the City of Jurupa Valley engaged the planning, biological, and cultural resource management services of FirstCarbon Solutions (FCS) to analyze the Rio Vista Specific Plan, prepare the EIR, and assist the City with response to public comment.
Due to the sensitivity of the Hurungna Oak, public opposition to the project focused on this unique biological and cultural resource. During the public comment periods and public meetings implemented as part of the City’s processing of the project through the California Environmental Quality Act (CEQA), the public raised questions about the effects of the project on the ecological integrity of the area that had allowed the Hurungna Oak to survive for millennia. FCS assisted the City in responding to public comments through conducting specialized studies of the Hurungna Oak to more fully assess baseline conditions at the site and to assess potential project impacts.
The Hurungna Oak
Palmer’s oak is an evergreen shrub or small tree that typically grows to a height of just 2-3 meters. Palmer’s oak is one of the so-called ‘scrub oak’ species – oaks with growth habits that are dense, low, and shrubby rather than the tall and tree-like forms most people imagine oak to be. Like other scrub oaks, Palmer’s oaks can reproduce both asexually through the production of clonal growths and sexually through the production of gametes (sex cells) and seeds (acorns). Some populations of Palmer’s oaks are represented by multiple clonal growths from a single plant.
‘Jurupa Oak’ or, as it is known by the Gabrieleño Band of Mission Indians-Kizh Nation, the ‘Hurungna Oak.’ The Hurungna Oak is a Palmer’s oak (Quercus palmeri), a species native to California, Baja California, New Mexico, and Arizona.
Palmer’s oak is distributed in a disjunct manner across its range, occurring in widely separated locations or localities rather than being evenly distributed. The species was more widespread and abundant at the end of the Pleistocene, but its range contracted to isolated areas during the Holocene as the climate became hotter and drier. Populations persisted in refugia – areas supporting relatively cool, moist conditions, such as canyons, springs, washes, and shaded slopes at elevations between 300 and 1,800 meters above sea level.
The Hurungna Oak is situated in the Jurupa Mountains, a small mountain range of the Peninsular Ranges that extends east to west across southeastern Pomona Valley. The location of the oak on a west-facing ridgetop is an unusual ecological situation, in that the site is seemingly more xeric and exposed than is preferred by the species. A niche modeling study determined that the site receives less precipitation and higher temperatures than other Palmer’s oak localities, leading the authors to conclude that the site is suboptimal. The apparently anomalous character of the site has prompted speculation that there may be a seep or natural subsurface water catchment basin there that provides water to sustain the Hurungna Oak through dry seasons/periods.
A study published in 2009 described the Hurungna Oak as a population of approximately 70 clonal stems that descended from a single individual. Based on annual growth ring counts in one of the Hurungna Oak stems and clonal regrowth rates in Palmer’s oaks at two other sites in southern California, the authors estimated the clone to be between 13,000 and 18,000 years old, making it the oldest known organism in California and the third oldest known organism on Earth. The original tree, as well as many previous generations of clones that descended from it, are no longer alive, but the genetic code they carried is still represented in the surviving clones. Thus, while the physical representation of the Hurungna Oak – its existing stems, leaves, and roots – are perhaps only a few hundred years old, the genetic code within these parts, its DNA, is many thousands of years old.
Public Opposition to Development Near the Hurungna Oak
The Rio Vista Specific Plan included designs for various residential, commercial, and industrial sites over the 900+ acre plan area, including more than 500 acres of open space. The Hurungna Oak is located on a hill within one of the proposed open space areas, where Richland Communities proposed to protect the site through a long-term conservation agreement. Without implementing this plan, the property and Hurungna Oak would remain unprotected and exposed to ongoing risks that had affected the site for decades, including trespassing, vandalism, and illegal dumping. Despite the protections the project would afford to the Hurungna Oak, opposition to the project was fierce, with most comment centered on one question: how close can development occur without harming the oak? The public has raised concerns and demanded studies to determine the water source for the Hurungna Oak, the nature of the ecological conditions that allowed it to persist, and an understanding of how implementing the project would affect the area and potentially cause harm to the oak. Some public and agency comments contended that the Hurungna Oak was able to persist at this location only through a mechanism that supplied extra water, and commenters proposed ideas for sources of the water that included a spring, or a natural bedrock catchment basin below the oak, or winter fog, or perhaps even groundwater. Commenters expressed concern that vibrations from construction equipment would damage the bedrock features that potentially provide water to the Hurungna Oak, that the roots of the oak would be damaged through vibrations and encroachment of the proposed development, and that the project would create an urban heat island that would cause harm to the Hurungna Oak and vegetation on the surrounding hillside. Due to the sensitivity of the Hurungna Oak and fierceness of public opposition to the Rio Vista Specific Plan, the project was featured prominently in news media for weeks. Searching for answers to alleviate public concern about potential project effects on the Hurungna Oak, the City reached out to FCS for help.
How Bedrock Features Sustain the Hurungna Oak
Initially, the City wanted to know: “What are the ecological conditions that favored the 13,000+ years of existence of the Hurungna Oak, and could any of these conditions be harmed by the project?” FCS Principal Biologist Dr. Michael W. Tuma started the investigation with an extensive literature review to characterize the ecological conditions at the Hurungna Oak locality. This included a review of peer-reviewed journal articles, news and magazine articles, herbarium records, previous reports concerning biological characteristics of the project area, and climate, geology, soils, and hydrology data.
A magazine article postulated that another bedrock feature, a subsurface basin, could be functioning as a water catchment and providing the Hurungna Oak with a sustaining source of water through dry seasons/periods. To investigate this possibility further, Dr. Tuma, with the assistance of Byram Archaeological Consulting, LLC, conducted a ground-penetrating radar investigation of the Hurungna Oak locality. The team determined that a 3- to 6-foot-deep bowl-shaped depression exists in the bedrock under the tree, seemingly confirming the hypothesis that subsurface bedrock holds water and sustains the Hurungna Oak through dry periods.
Together, the subsurface fractures in the bedrock that convey water to the Hurungna Oak locality and the subsurface bowl-shaped basin situated below the oak that holds water function to provide more mesic conditions at the locality, thereby allowing the oak to persist through periods of seasonal (summer) drought. The City’s focus shifted to identifying project activities that could compromise the integrity of the bedrock features that appeared to be supporting the oak. The City hired a vibration specialist to conduct a study to determine whether vibrations caused by construction machinery could harm the bedrock underlying the oak. They determined that a 259-foot buffer would be sufficient to ensure no damage to the bedrock or tree, and Richland Communities accordingly proposed to avoid using heavy machinery within 259 feet of the tree.
Protecting the Hurungna Oak’s Roots: Buffer Zones and Research
A second wave of public comments speculated that the project would be harmful to the roots of the Hurungna Oak. Richland Communities proposed a permanent avoidance buffer of 200 feet around the oak, but the public questioned whether it was sufficient for the protection of its roots. Commenters contended that the roots of the oak could extend laterally and to a depth of hundreds of feet from the Hurungna Oak locality, reasoning that the roots have had more than 13,000 years to grow to those extents, and that the proposed project would harm the root system, either through encroachment on the root system of the oak or lowering the water table so that its roots would no longer reach critical water reserves. The public demanded additional studies to determine the extent of the roots to have a full understanding of the effects of the project.
Seeking answers to these comments, the City engaged FCS to develop additional studies to assess techniques for measuring subsurface root systems and to estimate the extent of the Hurungna Oak’s roots based upon currently known information about Palmer’s oaks.
.jpg)
FCS Principal Biologist Dr. Tuma is conducting a field study of the Hurungna Oak on-site at the project location in the Jurupa Valley.
To address the City’s requests, FCS Principal Biologist Dr. Tuma reviewed current techniques that could be used to measure or map the extent of the subsurface roots of the Hurungna Oak, including ground penetrating radar, air excavation, tree trunk vibration, electrical capacitance, and X-ray computed tomography. None of the techniques examined could have provided a non-invasive method for measuring the Hurungna Oak’s root system, and FCS recommended against implementing these potentially harmful techniques. Dr. Tuma then examined published literature concerning the growth and extent of tree roots for Palmer’s oaks and other closely related scrub oak species. The review determined that, while there had been no studies published on the extent of root systems in Palmer’s oaks, there were studies of root systems in several closely related scrub oak species, including the canyon oak. The studies indicated that the root systems in these species extended up to 5 meters laterally from the above-ground expression of the tree and up to 9 meters deep. Furthermore, while the root system biomass of scrub oaks is typically about 3-6 times the amount of aboveground plant biomass, most of the root biomass is restricted to a depth of approximately 20-60 centimeters. Also, the roots of scrub oaks are often closely associated with subsurface bedrock, growing along the soil-bedrock interface and within cracks in the bedrock. Dr. Tuma concluded that the root system of the Hurungna Oak likely extended no more than 5 meters laterally and 9 meters deep, that the majority of the root system would be confined to the 3 to 6-feet deep subsurface depression in the bedrock, that the roots would grow along the soil-bedrock interface as well as within cracks in the bedrock, and that the proposed 200-foot permanent buffer and 259-foot no-heavy-machinery buffer would be sufficient to avoid impacts to the oak, its roots, and the underlying bedrock.
Community and Developer Consensus Reached to Protect the Hurungna Oak
The public was invited to provide additional comments during meetings of the City Planning Commission and City Council. The meetings were highly attended, and commenters took turns to state their support for or opposition against the project until late in the evening each time. A considerable amount of the comments were centered on the protection of the Hurungna Oak, and FCS Project Manager Yael Marcus and Dr. Tuma both provided testimony to address questions the Commissioners and Council Members had about the tree and the effects of the project.
Additionally, Richland Communities entered into a conservancy agreement with the Kizh Nation that appoints the tribe as the perpetual steward of the conserved area and the Hurungna Oak. This aspect of the project was applauded by the Planning Commission, and ultimately, the Rio Vista Specific Plan was approved by both the Planning Commission and City Council. The project will provide long-term protection of the Hurungna Oak that it currently does not have and will provide the Kizh Nation with a direct connection and responsibility for the Sacred Land occupied by the Hurungna Oak.
FirstCarbon Solutions (FCS), an ADEC Innovation, comprises more than 100 individuals offering due diligence, technical analysis, planning, environmental compliance, permitting, and mitigation/monitoring services for both public and private projects. FCS has more than 30 years of experience navigating environmental regulatory complexities. Contact us for a free consultation.
This blog provides general information and does not constitute the rendering of legal, economic, business, or other professional services or advice. Consult with your advisors regarding the applicability of this content to your specific circumstances.
