February 13, 2013
The Sierra Nevada Mountains, a spectacular mountain range located in California and Nevada, is not only a major source of California’s water supply, but is also home to hundreds of endemic species. During the fall and winter, a snowpack accumulates on the mountaintops and naturally melts during the spring, providing plants, animals, and people with a fresh source of water. In the past, the annual snowpack was enough to support these species as well as California’s water supply, however due to climate change and anthropogenic causes, precipitation has decreased and the snowpack is not able to accumulate the proper amount of snow like it has in past years. While the Sierra snowpack provides the majority of California’s water supply, it also is vital to the survival of the plants and animals in the Sierras. The snowmelt that supports these now endangered and at risk species are suffering. Higher temperatures, invasive species, and human influence are some of the causes that pose major threats to this ecosystem.
Some of these species include the bighorn sheep, yellow-legged frog, American pika, and Delta smelt. The bighorn sheep are one species who are severely impacted from the loss of snowpack because their natural habitat is being depleted. The bighorn, who has already had to recover from the brink of extinction in the 20th century, is an animal that utilizes the elevation to escape from predators. The warming temperatures has allowed the tree lines to move to higher elevations which encroaches on the bighorn’s living space and makes it more difficult for the bighorns to evade predators. The yellow-legged frog is also affected by the lack of snow because it depends on the snowpack to melt during certain times of the year to assure proper living conditions (doesn’t freeze in the winter, but has enough water in the summer to lay eggs). Additionally, they are at risk because of the numerous invasive species that are preying on the frogs during their tadpole stages. Another species that has been severely impacted by the decline of snowpack is the American pika. The pika is a small hamster-like creature that has a minuscule temperature window and relies on the snowpack for insulation in the winter and moderate temperatures in the summer. In response to the unbearable temperatures, the pika have been forced to move upslope, an unsafe habitat for the vulnerable animal, which has already become extinct in some low-lying areas. Lastly, the Delta smelt, like salmon, is an upstream swimming species of fish that is reliant on the cold downstream that the snowmelt usually provides. “As the headwaters decrease and temperatures rise, endangered fish species such as the Delta smelt will suffer.” (Merry) Not only are animals suffering as a result of decreased snowpack and higher temperatures, but plants are also feeling the effects.
Conifer trees are surprising less resistant to the hotter temperatures and decrease in precipitation. The trees are dying much more often than in previous years because of warmer temperatures and evaporated moisture in the soil. In addition, the conifers are also being infested by fungi and insects that thrive in the warmer climates. Both drier conditions and increased temperatures have led to an increase in wildfires. A positive feedback loop is created when trees that catch fire release carbon dioxide stored in their trunks, which is in turn absorbed into the atmosphere, further advancing global climate change.
The Sierra snowpack is a crucial part of this environment that requires mitigation in order to protect the vulnerable species that rely on its abundance. The Sierra Club proposes a great strategy as to how to protect these animals and is a decent step towards finding a solution that solves the issue at hand. They propose that a core area and a buffer zone are necessary so that species are able to withstand the changes that are occurring within their habitats. Although some steps that will help alleviate the issue are in action, state legislature would be a strong supplement that may drastically increase the revitalization of species in the Sierra Nevada ecosystem.
This post was authored by Dana Handy, a sophomore majoring in Environmental Studies, and Angel Marquez, a sophomore double majoring in Economics/ Mathematics, and Business Administration.
September 12, 2011
Water supply in California’s Sierra Nevada range is primarily determined by seasonal precipitation, which occurs for the most part in the fall and winter seasons. The runoff from this precipitation provides substantial flow during spring snowmelt for animals, plants and humans. Through various measurements taken by various stations posted throughout the Sierra mountain range, it is evident that annual snowfall and precipitation has decreased and will continue to do so as climate change and anthropogenic influences heat the earth (Hall and Kapnick 2010). The decreases in snowmelt coupled with anthropogenic influences in the Sierras are posing many abiotic and biotic pressures on plants and animals living in the region and many are on the verge of extinction. Home to 135 threatened plant species and providing “as much as 65 percent of California’s water supply”, the Sierra mountain range remains a crucial habitat for humans, animal and plant species.
Decreased snow melt and anthropogenic influences, such as the introduction of non native species to the Sierra Nevada’s water sources, have posed a serious threat to species such as the Sierra Nevada yellow-legged frog or Rana sierrae, which are native to the area. The Rana sierrae relies on perennial sources of water in order to survive into adulthood, but with the introduction of trout, which prey on Rana sierrae in all three stages of their life, into deeper bodies of water, the Rana sierrae has had to rely on inferior and shallower fishless water sources, which often times run dry in the summer due to decreased snow melt and climate change (Mathews and Preisler 2010). As climate change and anthropogenic influences encroach on the Rana sierra’s habitat, they will eventually become extinct in the region and thereby decrease the rich biodiversity.
Unfortunately, other species inhabiting the Sierra Mountains are reacting more severely to increased temperatures than scientists had anticipated. “What surprised us are how sensitive these trees are to short-term changes in climate,” says U.S. Geological Survey’s Phillip van Mantgem, who conducted a study measuring the mortality rate of Sierra’s coniferous species. Beginning in 1983, Mantgem found that by 2007 the death rate had nearly doubled. The conifer’s lower survival rates can greatly be attributed to increased temperatures. The Sierra Forest Legacy notes that during a recent 22-year period, “the Sierra Nevada warmed by 1.8 degrees Fahrenheit”. Despite no apparent fluctuation in the average precipitation during this 22-year period, increased temperatures have led to higher evaporation rates creating dryer soil conditions. The University of California Santa Cruz also conducted a study on the impact of climate change on Sierra’s Pinus contorta and P. jeffreyi seedlings. The study noted a significant decrease in the survival rate of the seedlings – attributed to the seedling’s shallow root system and lower capacity to store water (Alpert 48-49). In addition to decreased irrigation, the conifers also currently suffer from an increased infestation of fungi and insects, which gravitate towards warmer climates. Additionally, the combination of warmer temperature and more dried dead plant species, makes the environment more susceptible to fires, threatening the release of CO2 previously stored in the trunks of the trees. This release of CO2 will create a positive feedback to the global climate dilemma, sadly leading scientists and conservationist back to where they started.
About the authors: Stephen Holle and Birka Burnison are working towards their bachelor’s degrees in Environmental Studies in the USC Dana and David Dornsife College of Letters, Arts and Sciences.