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)