Welcome to the Nature Reserve of Orange County (NROC, or Reserve) Ecological Health Assessment (EHA), an in-depth look at the condition of key natural resources and ecosystems across this landscape. The assessment is based on a suite of indicators (e.g., plants, wildlife, threats) that reveal something about the Reserve's health. You can learn more about each one through the links on this page.
The approximately 37,000-acre (14,978-hectare) Reserve was established in 1996 as one of the first steps following the signing of a landscape-scale habitat planning and conservation effort: the Natural Communities Conservation Plan/Habitat Conservation Plan (NCCP/HCP) for the Central and Coastal Subregions of Orange County, California.
Since then, rapid development, invasive species, wildfires, and climate change have continued to affect the Reserve’s plant and animal species. This is the first systematic survey to address the question of how well the Reserve and its adjacent lands have served as a refuge for the species it was established to protect.
The assessment represents the results of an unprecedented collaboration among NROC’s land managers and the research community, who used the most current data and best expert judgement to understand and evaluate the Reserve’s health. It establishes an important benchmark by which both current and future managers can measure change across jurisdictional boundaries. It also reveals areas where there is insufficient evidence to draw meaningful conclusions and highlights opportunities for future monitoring, research, and collaboration.
What Have We Learned About the Reserve’s Health?
Based on a suite of metrics developed to measure the health of key ecological indicators, the condition of NROC’s natural resources is caution, with a mix of indicators that are doing well, some that are of significant concern, and most that are in a state of caution. The trend is unchanging, but right on the cusp of declining. This reflects the ongoing threats these species and habitats face from habitat loss, too-frequent fires, drought, and more. It is notable that not a single indicator had an increasing trend. Overall, our confidence in this assessment is moderate, based on the quality, quantity, and recency of data and expert opinion.
The geographic extent of this assessment—the EHA Study Area—was divided into Central and Coastal Study Areas (see map). When looking at how these same indicators are faring in each of these areas separately, we see that many are in a state of caution, while others are a mix of good and significant concern. Overall, the condition for each area has been determined to be caution. (Find links to more detailed information on each indicator species at the bottom of this page.)
Explore the EHA’s Approach and Methods, including how expert teams selected indicators, analyzed trends, and evaluated threats to determine whether long-term conservation goals are being met.
For this project, the land inside the boundaries of the EHA Study Area in Orange County, California, was divided into two distinct regions: the Central Study Area and the Coastal Study Area. Each health indicator was evaluated for each area separately, unless they are only found in one or the other.
The Reserve’s protected areas are a refuge for many animal species that have lost homes elsewhere in the region. Several species that are important indicators of the health of those habitats are included here.
The foundation of all of the Reserve’s habitats, plant communities play critical roles in its overall ecological health. Several key communities were assessed as a part of this evaluation.
Ecological stressors are things like fire, drought, or invasive species that affect the Reserve’s health. Several of these were evaluated as a part of this assessment.
The condition of many important indicators of the Reserve’s ecological health remains largely unknown. Needs statements suggest potential metrics, monitoring approaches, and data sources that could be used to evaluate them in the future.
Arthropods
Making up 84% of known animal species, arthropods play vital roles as pollinators, herbivores, decomposers, and prey for other animals. Alarmingly, terrestrial arthropods are currently undergoing an “insect apocalypse,” with many studies reporting 70%–90% population declines over the past few decades. A baseline for these species in the EHA Study Area would help determine how they are faring here.
Bats
A primary predator of flying insects, bats are crucial in controlling pest populations and providing other ecosystem services such as plant pollination and seed dispersal. Their populations are in decline due to habitat loss, increasing fire frequency, and climate change.
Light-Footed Ridgway’s Rail
The endangered Light-footed Ridgway’s Rail depends on healthy coastal marshes but has declined sharply at Upper Newport Bay in the EHA Study Area due to habitat loss, flooding, and predation. Conservation efforts (i.e., marsh restoration, captive breeding, artificial rafts) aim to protect this species, whose population trends signal the overall health of wetland
Raptors
Eagles, hawks, falcons, and owls are often their ecosystems’ top predators. Many are also migratory, requiring extensive, healthy ecosystems for feeding and breeding. Their sensitivity to large-scale environmental changes makes them vital indicators of overall ecological health. While some studies have been done, no systematic assessment of the Reserve’s raptor populations has been undertaken.
Rare Plants
Sixty-four rare plant species are found in the EHA Study Area, many of which are tied to unique habitats, soils, or pollinators, making them important indicators of ecosystem health and conservation effectiveness. Because funding is limited, monitoring needs to focus on the rarest and most vulnerable species, especially those at risk from disturbance, climate change, or land use impacts.
Recreation
The Reserve provides a place for outdoor recreation for millions of residents, but unmanaged use can negatively affect both ecosystems and visitor experiences. While some monitoring exists, to guide sustainable management, a comprehensive program that tracks visitor use, resource conditions, and experience quality is needed.
Small Mammals
Small mammals provide food for predators, control invasive plants, and signal habitat quality, making them key to evaluating ecosystem health. However, other than directed pocket mouse surveys, few efforts have been made to monitor small mammal diversity and abundance in the EHA Study Area.
Soil Microbes
Soil microbes play a vital role in nutrient cycling, contribute to soil structure and formation, and promote carbon sequestration. They affect animal health, pollution remediation, and seed germination, making them important tools for managing a healthy ecosystem. Data on the health of the Reserve’s soil microbes could be gathered based on biological, physical, and chemical characteristics.
Woody Riparian Habitat
Riparian areas are one of the few wet areas in an otherwise dry environment and provide critical habitat for a host of species. They are also the most sensitive to changes from drought, climate change, and human alterations to the environment. However, little is known about the extent or condition of the Reserve’s riparian habitats.