Human Impact on the Coniferous Forest Ecosystem of the Sierra Nevada

Human Impact on the Coniferous Forest Ecosystem of the Sierra Nevada

Although the major uses of the coniferous forest of the Sierra is for recreation and sight-seeing within the forest, humans pose many environmental threats within the Sierra.  For example, Sierran forests show the effects of decades of fire suppression (and current fire suppression), which is changing the character of the forests. (www.fs.fed.us/psw/publications/millar/psw_1996_millar021.pdf) "Wildfires are a yearly occurrence in the Sierra Nevada. Low fuel moisture, high temperatures and human impacts in the wildland-urban interface combine into the ideal conditions for fast-moving fires. At the same time, ozone pollution levels regularly approach unhealthy levels. The area itself does not generate the pollution, but prevailing winds push pollution out of the Bay area and Sacramento corridor against the foothills and peaks of the region. U.S. EPA and the American Lung Association have consistently ranked Nevada County among the dozen most ozone-polluted counties in the nation." (Pascale Fusshoeller, 2011.  (http://www.reportingonhealth.org/blogs/air-pollution-and-wildfire-impacts-sierra-nevada)

Another impact on the Sierra via human interuption is the non-native trout introduction into Sierran lakes. "'Trout are highly-effective predators and their impacts on prey species are well-documented (e.g., Northcote 1988). This impact may be particularly severe in oligotrophic lakes such as those found in the Sierra Nevada, since the relatively simple food webs of such lakes are believed to make them especially sensitive to impacts from introduced species (Li and Moyle 1981; McQueen, et al. 1986). In fact, based on an extensive survey of lakes in the Sierra Nevada, Bradford et al. (1994a) concluded that "the most profound human impacts on aquatic communities in the High Sierra appear to be related to historical and on-going stocking of exotic fish species into High Sierra waters'" (Knapp and Marine Science Institute of California, UCSB, 1996) (http://www.highsierrahikers.org/issue_fish_main.html)

Another detrimental impact on the forest is logging and all the effects of logging, such as road building, habitat fragmentation and wildfire risk. This detrimental impact by humans on forests are evidenced by irresponsible and misguided logging prescriptions being issued. They are not only bad public policy but are also likely to degrade the ecosystem functions of our national forests, increasing the likelihood of future severe fires, increasing greenhouse gas emissions, and impacting other resource values. There are countless negative effects logging causes, here are a few:

-"Road building during logging operations directly leads to many negative consequences for wildlife, aquatic health, and the ecological integrity of the forest. The roads cause forest fragmentation which creates more area of forest open to cleared and non-native land, which ultimately pushes the natural habitat for animals further and further into the forest, destroying their natural habitat." (Sierra Forest Legacy, 2012)
-Watersheds and aquatic environments are effected as well. The trees deep root systems normally help act as an anchor for the sediments in the ground, keeping it from all draining away during rain. When there is no deep root system, the sediments are washed away and drain into streams and rivers which eventually destroy the natural river systems. The trees also create cover from the sun for most rivers, and when the rivers are exposed to sun, they warm up and their pH levels change, which highly effects the aquatic wildlife.

-Soils are also greatly affected when trees are cut down. The trees deep root systems normally help act as an anchor for the sediments in the ground, keeping it from all draining away during rain. When there is no deep root system, the sediments are washed away and drain into streams and rivers which eventually destroy the natural river systems.

-Possibly the most serious affect of human logging is causal global warming. "Logging old forests contributes to global warming through removing significant sources of sequestered carbon. After logging, the local microclimate is altered, resulting in hotter and drier conditions which contribute to increased fire hazard. These impacts will affect the natural environment, and eventually will affect human life." (Sierra Forest Legacy, 2012)(http://www.sierraforestlegacy.org/FC_FireForestEcology/FFE_LoggingImpacts.php#Top)