The Monterey Cypress (Cupressus macrocarpa) is a California Central Coast endemic species – listed as a ‘Category 1’ rare and endangered species by the state of California, with only two native populations remaining. The species’ natural distribution range is confined to two small populations within 10 miles of one another – Allan Memorial Grove in Point Lobos State Nature Reserve and Crocker Grove in Pebble Beach, Carmel (California State Parks 2018: 4-48; Point Lobos Foundation n.d.). The “exceedingly limited area of its natural home may have been caused by changes in climatic conditions” (California State Parks 2018: 4-48). This historic trend throws caution to the potential for future sensitivity of Monterey Cypress native populations to climate change.
The small native population size also suggests lack of genetic diversity. Genetic diversity within a species population provides adaptive capacity by increasing the likelihood that individuals within the population may have heritable traits that increase tolerance of the species to climate change (National Wildlife Federation 2011: 49). This further indicates the Monterey Cypress’s vulnerability to climate change.
In addition, limited natural range indicates the species’ poor dispersal ability. “In general, species with poorer dispersal abilities are more susceptible to climate change” (National Wildlife Federation 2011: 49). Rising atmospheric temperatures as a result of climate change is set to weaken this ability further. Under high emissions scenarios, the average annual temperature is projected to increase by 1.8°C by 2070 in the region relative to the modelled historical period (Langridge 2018: 13). Allan Memorial Grove is experiencing an increase in the population growth rate of invasive grass species, in particular, Leafy Bent Grass (Agrostis pallens) (Lee 2021). Invasive grass species interrupt Monterey Cypress reproduction by hindering the dispersal ability of seedlings, as well as blocking their access to direct sunlight. The change in vegetation and species distribution around the stand is exacerbated by increasing temperatures in the region that enable the grasses to grow at a faster rate, disrupting the optimal conditions cypress seeds need to germinate. This climate-informed phenomenon may pose a threat to the continuation of Monterey Cypress at Allan Memorial Grove.
Distributional Range: Range is the geographical area within which a species can be found. Within that range, distribution is the general structure of the species population.
Genetic Diversity: The variation in the amount of genetic information within and among individuals of a population, a species, an assemblage, or a community.
Adaptive Capacity: The general ability of institutions, systems, and individuals to adjust to potential damage, to take advantage of opportunities, or to cope with the consequences.
Dispersal: The dissemination of offspring of plants or sessile animals. Dispersal provides organisms that are not mobile with a better chance of survival by reducing competition among offspring and parents and promoting colonization of new habitats.
Emissions scenarios: Possible pathways that society might take in the emission of greenhouse gases in the future.
Stand: An aggregation of trees or other growth occupying a specific area and sufficiently uniform in species composition, size, age, arrangement, and condition as to be distinguished from the forest or other growth on adjoining areas.
Native Species: Indigenous species of animals or plants that naturally occur in a given region or ecosystem.
Invasive Species: A non-native species that spreads rapidly and outcompetes, preys on and otherwise reduces or eliminates populations of native species.
References
California State Parks, 2018. Preliminary General Plan and Draft Environmental Impact Report. Carmel Area State Parks.
IPBES secretariat. n.d. Glossary | IPBES secretariat. [online] Available at: https://www.ipbes.net/glossary[Accessed 14 June 2021].
Lee, K., 2021. Informational Interview on Point Lobos SNR.
National Wildlife Federation, 2011. Scanning the Conservation Horizon: A Guide to Climate Change Vulnerability Assessment. Washington, D.C.
Point Lobos Foundation, n.d. Trees | Point Lobos Foundation. [online] Available at: https://pointlobos.org/learn- more/wildlife-plants-birds-and-geology/plants/trees [Accessed 10 March 2021].
Tierney, K., 2021. Monterey Cypress Forest at Allan Memorial Grove. Monterey, CA.