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Old 12-14-2010, 02:23 PM   #1
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Default Ecological disturbance as management tool.

Speaking of consequences, you can read a bit about what has been learned about deliberate use of ecological disturbance to manage biodiversity.

Managing nature reserves using ecological disturbances can easily go wrong


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The most concrete and manageable definition is that a disturbance must kill or remove organisms in a community (an area with co-existing species), so making it easier for new species to become established. The seemingly innocuous sub-clause about the establishment of new species has proved surprisingly important when testing ecological explanatory models for disturbances and biodiversity.
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The best-known example of this type of management can be found in Yellowstone, the world's oldest national park. In Sweden the method is used at Alvaret on the island of Öland, where the landscape is kept clear by grazing (a form of biological disturbance
full text
Svensson J. Robin 2010
ECOLOGICAL DISTURBANCES: THE GOOD,THE BAD AND THE UGLY
http://gupea.ub.gu.se/bitstream/2077...77_23772_1.pdf

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Intermediate disturbance hypothesis IDH

At low levels of disturbance diversity will be low due to competitive exclusion and few species can persist at high levels of disturbance.

Dynamic Equilibrium Model DEM effects of disturbance depend on the productivity of communities,because at higher growth rates a stronger disturbance is required to counteract increased rates of competitive exclusion.

smaller less frequent disturbances differ from larger infrequent disturbances.

biological disturbances (here grazing), physical disturbances (here wave action or scraping)
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Old 12-15-2010, 02:18 AM   #2
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I read that over at Science Daily!!! They’re probably referring to prescribed burns at Yellowstone. I haven’t run across ‘Ecological disturbances: The Good, the Bad and the Ugly’ before. I’m totally excited…philosophically speaking ….about reading his article in its entirety when I’ve got a chance to absorb it and find a translation… I quit reading when the text reverted to Sweedish. I’m liking what I’ve read so far…. particularly his inclusion of numerous operational definitions of disturbances. I’d agree this was the best,

According to Sousa (1984), disturbance is defined as “…a discrete, punctuated killing, displacement, or damaging of one or more individuals (or colonies) that directly or indirectly creates an opportunity for new individuals (or colonies) to become established.

1st thought that popped into my head was my small-scale removal of non-native earthworms from my own property and then much larger scale removals of rats and cats from island ecosystems. Some “disturbances” can give the “natives” a much needed leg up. “GO Natives”!!!
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Old 12-29-2010, 11:30 AM   #3
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I had no trouble reading the entire 25 pages.

I can see where knowing more about what happens to diversity in a given area, after a disturbance, is helpful in using manmade disturbance as a managing tool.

How often to disturb, how severe the disturbance and the available pool of species to recolonize after a disturbance all must be taken into account.

With prescribed burns that might mean burning smaller patches at each burn or only burning any given section every few years. When plant remains are burned any creatures with limited mobility may not survive. (larvae,eggs,chrysalis,etc...)

When using grazing animals waiting until after initial spring growth and fencing to limit the time any area is grazed allows more species to survive.
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Old 12-29-2010, 12:01 PM   #4
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Originally Posted by Equilibrium View Post
I quit reading when the text reverted to Sweedish.
You're gonna let something minor like a foreign language stop you?
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Old 12-29-2010, 01:18 PM   #5
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Biigblueeyes, google will do a translation for you. But if you keep scrolling it goes back to english, so no translation necessary in this case.
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Old 12-31-2010, 12:58 PM   #6
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The author fails to mention any species of grazing animal. Unfortunately, horses and grazing livestock are frequently responsible for untold ecological damages.

For example, cattle. Cattle contaminate water with feces and destroy native vegetation while damaging soils.
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Old 01-29-2011, 12:24 AM   #7
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Lorax, I just finished reading Miracle Under The Oaks by William K Stevens. The grazing animals mentioned for use on National Grasslands was
elk and Bison. Once upon a time the prairie dog towns did much of the same sort of disturbance.
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Old 02-09-2011, 12:40 PM   #8
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More about disturbance ecology.

Causes of Change in an Ecosystem: Disturbances and Invasion, When a Dominant Species is Removed, and More

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Historically, a disturbance in an ecosystem is defined as "a discrete event in time that disrupts ecosystems or communities, changes substrate and/or resource availability, and creates opportunities for new individuals or colonies to become established."

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Disturbances might be caused by abiotic events like fires, storms, floods, droughts, or changes in water currents. They might have a biological origin, such as trampling by large grazing herbivores, underground tunneling by moles or prairie dogs, bioturbation of marine sediments, deforestation, or off-road vehicles.
Disturbance and Diversity: An Ecological Chicken and Egg Problem | Learn Science at Scitable

Disturbance and Diversity: An Ecological Chicken and Egg Problem
By: A. Randall Hughes
(Coastal and Marine Laboratory, Florida State University) © 2010 Nature Education Citation: Hughes, A. (2010) Disturbance and Diversity: An Ecological Chicken and Egg Problem. Nature Education Knowledge 1(8):26


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Species Diversity Affects Resistance and Resilience to Disturbance
In addition to strong evidence for disturbance effects on diversity, both theory (MacArthur 1955; May 1973; Yachi & Loreau 1999, Loreau et al. 2003) and experiments (Tilman 1996; Mulder et al. 2001; Cardinale & Palmer 2002; Allison 2004; Hughes & Stachowicz 2004) demonstrate that diversity can affect community stability by influencing the response to disturbance and/or environmental fluctuations. For instance, more diverse assemblages are more likely to display a range of functional traits, increasing the probability that one species can compensate for the negative responses of other species to disturbance or environmental change (the insurance hypothesis; e.g., Tilman 1996). A related mechanism is the portfolio effect: if the abundance of different species fluctuates independently, or at least out of phase with one another, then these fluctuations will average each other out, leading to less variation over time in a diverse assemblage (Doak et al. 1998)
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In addition to effects of species diversity, population and genetic variation within species can also affect realized disturbance and variability over time (see references in Hughes et al. 2008). In some cases, the effects of diversity within species can be far-reaching. For example, diversity among sockeye salmon populations in life history characteristics and spawning habitat increases resistance to disturbance and enhances productivity and sustainability in the sockeye salmon fishery, currently the most valuable fishery in the US (Hilborn et al. 2003; Schindler et al. 2010; Figure 4). (In this case, the agent of distrurbance is fishing itself, which results in the removal of salmon biomass from the community). Without the buffering effects of population and life history diversity, variability in overall salmon abundance would increase, leading to a 10-fold increase in fishery closures (Schindler et al. 2010). These benefits of salmon population diversity in the face of fishing pressure argue for greater attention to the influence of within-species diversity on disturbance response and stability.
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