Beaver Dams

3.5 million miles of water run throughout the United States; and since the country’s conception, over 80,000 dams have impounded 600,000 miles of these waters [1]. Dams were originally constructed to provide water to towns and establishes energy sources for mills and later hydroelectric plants. Because these dams were constructed decades ago, they’re reaching a critical point of obsoleteness where they cause more harm than good. Dam removal is increasingly popular across the country to address the ecological problems including habitat loss and sedimentation, despite potential for downstream harm, removing dams is more environmentally and economically cost effective than upgrading them. The Marmot, Glines Canyon, and Elwha river dam removal projects each highlight different challenges of dam removal, but overall

The construction of major dams and development areas has shrunk the area that the sandhill cranes used to roost while on their migration. Krapu et al. (2014) completed a ten year study to determine the major stopovers, migration routes, and migration timeline of the sandhill cranes. The team of researchers determined that management of the trees along the Platte River has positively impacted the sandhill cranes. Since the dams have been built in the river, the natural flooding of the river has ceased. The flooding stripped cottonwood trees from the river banks. The sandhill cranes prefer to roost in open aquatic areas. The damming of the Platte River has stopped the floods; therefore, stopping the stripping of the cottonwoods (Landry et al., 2014). In areas when conservationists have cut the trees back, the sandhill cranes have returned to

The bar chart was used to compare the number of species in each transect. In transect A, there were 5 different species. The species in this area were mostly grass, forbs, moss, bugs and beetles. Bugs and beetles made up a small population of this transect. In transect B, there were also 5 species. The species were mostly grass, shrubs, forbs, moss and bugs. In this transect, shrubs were found which makes transect B more diversed than A. In Transect C, 8 species were located in this area. The species included shrubs, grass, fobs, evergreen, trees, dirt, bugs and spiders. New species such as evergreen, trees, dirt and spiders were located in this location. Therefore the test that diversity happens through ecological succession was

Beside these arguments, there is also a more quantitative side to the debate. The ecological detriments of the Glen Canyon Dam have been well-documented. Extensive changes were brought about in the Colorado River ecosystem by the construction of the Glen Canyon Dam. Most of these alterations negatively affected the functioning of the system and the native aquatic species of the river. The reduced supply and transport of

4. Compare snowpack in a watershed to a dam on a river. How are they alike? How are they different?

“Restoring an ecologically complete ecosystem in Yellowstone requires the return of willows--and with them, beavers. There's a clear threshold for ecosystem recovery. Willow stands must be more than 6 feet tall, the scientists found. That height is important, says Marshall. Then willows are beyond the reach of browsing elk, and can serve as seed sources for new young willows. Once willows have returned, beavers will gnaw down a certain number of them to build dams. The dams will further slow stream flow, allowing yet more willows to grow. The results offer new insights on the role of wolf-driven trophic cascades in the Yellowstone ecosystem, says Hobbs. Trophic cascades like that in Yellowstone occur when predators--or the lack thereof--in an ecosystem change the abundance or alter traits of their prey, in turn affecting the next lower trophic level.” ("National Science Foundation", 2013)

The Point Arena mountain beaver (Aplodontia rufa nigra) is a federally listed endangered subspecies that is restricted to the small area of Point Arena, in coastal Mendocino County, California (Zielinski, et al., 2013). (See Figure 1). The Point Arena mountain beaver is a dark brown, medium-sized burrowing rodent with small ears and eyes, and long whiskers and claws (National Park Service (NPS), n.d.). The subspecies is semi-fossorial, spending most of its five to six year lifespan in underground burrows (United States Fish & Wildlife Service (USFWS), 2011). The burrows are typically found on moist and steep north-facing slopes or in well-drained gullies; each burrow contains separate chambers for food storage, nesting, and excrement (NPS,

The ancient forests of the Northeast aren’t the only aspect of the bioregion that’s fate have been at perpetual risk since the early settlement of Europeans. There is no question that forests still dominate the landscape of Northeastern region accounting for “60% of the total land area, and in New England alone, the coverage is 80%”. Still the species that exist within the understory of the forests have undergone an equally dramatic transformation because of human interaction with the land and the harvest of its resources. Some species in the understory of the mixed forests of the Northeast have been driven out of the region, are under intense ecological pressure, are on the brink of extinction, or have already gone extinct in the region. Perhaps one of the most harmful and impactful effects colonization of the Northeast has had on the resources of the land is the introduction of non-native species and diseases into the region. Over time the overall makeup of the forests have changed drastically as an example, “…the American chestnut once made up as much as 25% of the trees in some areas and was economically the most important hardwood in the Eastern forests”. The introduction of chestnut blight at the turn of the century accounts for

-Growth in beaver populations meant more dams which had multiple beneficial effects on streams and rivers. Dams slow seasonal water runoff and help to maintain a healthy water supply. The pools created by dams also created good habitats for fish. More abundance of willows made great songbird habitat.

In 1992, The Elwha River Ecosystem and Fisheries Restoration Act of 1992 authorized the US Federal Government to acquire the hydroelectric power projects of Elwha Dam and Glines Canyon Dam, where are located on the Washington State for demolition for habitat restoration and decommissioning. The dam removals began in 2011 and finished in 2014. I wondering that why government decided to remove the dam and what happens in Elwha River after dam removal. In this paper, I write about the following topics: main purpose of the Elwha and Gliens Canyon dam, effects to the Elwha River as well as ecosystem after constructing dam, reasons of the dam removal, process of the dam removal, and effects after dam removal.

The real question here however is why these dams were installed. Well you see, it all goes back to the Gold Rush. Most accounts of the environmental damage caused by the Gold Rush focus on the direct effects of mining. During the gold rush, many farmers saw the open opportunity to take advantage of miners that had traveled from across the world. They increased the value of their food to outrageous prices.

In area one, the douglas fir was the dominant one in the area , then following that was the bay . This only shows only two species allocating in the area that siphons resources. If one declines, the other dominants , this does not show as much diversity in that aspect. In area 2, there was spread of dominance, the species that had the greater dominance was oregon white following that was the black oak, then the live oak then the bay. This shows more diversity than area 1.

After doing extensive research on the American beavers (Castor canadensis), I am most optimistic about population growth for this species. These semi-aquatic mammals are a keystone species and amazing ecosystem engineers who indirectly contribute tremendously to biodiversity, stabilization, and trophic cascades within boreal forest. Major challenges this species faces is human encroachment within their habitats due to beavers notorious behavior in creating dams, which can positively and negatively impact the environment. This often creates issues for humans in terms of flooding or clogging in streams, pipes, or culverts. Unfortunately, the public's terms of removal can result in killing, which factor into decline in population.

Beavers construct dams in order to restrict the flow of moving water, creates a difference in water depth, which aid in building their lodges.1 Figure 1 and 2 illustrates this function clearly. A clear difference in water level is clearly evident, with the right side having approximately 1ft to 1.5ft water and the left side having approximately 0.25ft to 0.50ft of

Most dams and reservoirs are built in order supply water, generate electricity, and to control flood plains. It is known that the damming of a river can negatively affect abundance nutrient, habitat, sediment, and flow regimes (Ligon 1995). Studies have also shown that dams immensely influence fish assemblages. Once a reservoir is built it immediately impacts a fish community by changing habitat quality and the flow regime. The main impact that dams have on aquatic ecosystems is the change of flow regime from lotic to lentic (Agostinho 2008). Lotic systems are typically categorized as free-flowing systems examples of these are rivers and streams. Lentic systems can be classified as sedentary systems because they do not actively flow. Some examples of these Lentic systems are pools and backwaters. Longnose gar (Lepisosteus osseus) are known to spawn in flowing systems such as streams and some Lepisosteus will also migrate to streams in order to spawn. Dams, channel straightening, road construction, flow alteration and pollution have caused a decrease in habitat (Gonzalez 2008). The construction of dams can create a barrier that can make migrating and accessing spawning sites more difficult. Studies have shown that male Lepisosteus that are found downstream from a dam will have significant reduction in size, condition, growth, and relative gonad size (Johnson 2011).