Displaying items by tag: Nature camp

DISTRIBUTION AND HABITAT:

 Eurasian milfoil first arrived in Wisconsin in the 1960's. During the 1980's, it began to move from several counties in southern Wisconsin to lakes and waterways in the northern half of the state. As of 1993, Eurasian milfoil was common in 39 Wisconsin counties (54%) and at least 75 of its lakes, including shallow bays in Lakes Michigan and Superior and Mississippi River pools.
Eurasian water milfoil grows best in fertile, fine-textured, inorganic sediments. In less productive lakes, it is restricted to areas of nutrient-rich sediments. It has a history of becoming dominant in eutrophic, nutrient-rich lakes, although this pattern is not universal. It is an opportunistic species that prefers highly disturbed lake beds, lakes receiving nitrogen and phosphorous-laden runoff, and heavily used lakes. Optimal growth occurs in alkaline systems with a high concentration of dissolved inorganic carbon. High water temperatures promote multiple periods of flowering and fragmentation.

LIFE HISTORY AND EFFECTS OF INVASION: 

Unlike many other plants, Eurasian water milfoil does not rely on seed for reproduction. Its seeds germinate poorly under natural conditions. It reproduces vegetatively by fragmentation, allowing it to disperse over long distances. The plant produces fragments after fruiting once or twice during the summer. These shoots may then be carried downstream by water currents or inadvertently picked up by boaters. Milfoil is readily dispersed by boats, motors, trailers, bilges, live wells, or bait buckets, and can stay alive for weeks if kept moist.
Once established in an aquatic community, milfoil reproduces from shoot fragments and stolons (runners that creep along the lake bed). As an opportunistic species, Eurasian water milfoil is adapted for rapid growth early in spring. Stolons, lower stems, and roots persist over winter and store the carbohydrates that help milfoil claim the water column early in spring, photosynthesize, divide, and form a dense leaf canopy that shades out native aquatic plants. Its ability to spread rapidly by fragmentation and effectively block out sunlight needed for native plant growth often results in monotypic stands. Monotypic stands of Eurasian milfoil provide only a single habitat, and threaten the integrity of aquatic communities in a number of ways; for example, dense stands disrupt predator-prey relationships by fencing out larger fish, and reducing the number of nutrient-rich native plants available for waterfowl.
Dense stands of Eurasian water milfoil also inhibit recreational uses like swimming, boating, and fishing. Some stands have been dense enough to obstruct industrial and power generation water intakes. The visual impact that greets the lake user on milfoil-dominated lakes is the flat yellow-green of matted vegetation, often prompting the perception that the lake is "infested" or "dead". Cycling of nutrients from sediments to the water column by Eurasian water milfoil may lead to deteriorating water quality and algae blooms of infested lakes.

CONTROLLING EURASIAN WATER MILFOIL:

Preventing a milfoil invasion involves various efforts. Public awareness of the necessity to remove weed fragments at boat landings, a commitment to protect native plant beds from speed boaters and indiscriminate plant control that disturbs these beds, and a watershed management program to keep nutrients from reaching lakes and stimulating milfoil colonies--all are necessary to prevent the spread of milfoil.

Monitoring and prevention are the most important steps for keeping Eurasian water milfoil under control. A sound precautionary measure is to check all equipment used in infested waters and remove all aquatic vegetation upon leaving the lake or river. All equipment, including boats, motors, trailers, and fishing/diving equipment, should be free of aquatic plants.
Lake managers and lakeshore owners should check for new colonies and control them before they spread. The plants can be hand pulled or raked. It is imperative that all fragments be removed from the water and the shore. Plant fragments can be used in upland areas as a garden mulch.

DNR permits are required for chemical treatments, bottom screening, buoy/barrier placement, and mechanized removal.

Mechanical Control:

 Mechanical cutters and harvesters are a common method for controlling Eurasian water milfoil in Wisconsin. While harvesting may clear out beaches and boat landings by breaking up the milfoil canopy, the method is not selective, removing beneficial aquatic vegetation as well. These machines also create shoot fragments, which contributes to milfoil dispersal. Harvesting should be used only after colonies have become widespread, and harvesters should be used offshore where they have room to turn around. Hand cutters work best inshore, where they complement hand pulling and bottom screening. A diver-operated suction dredge can be used to vacuum up weeds, but the technique can destroy nearby native plants and temporarily raise water turbidity.

Hand pulling is the preferred control method for colonies of under 0.75 acres or fewer than 100 plants. The process can be highly effective at selectively removing Eurasian water milfoil if done carefully; special care must be taken to collect all roots and plant fragments during removal. Hand pulling is a time-consuming process.
Bottom screening can be used for small-scale and localized infestations on sites with little boat traffic, but will kill native vegetation as well. The bottom screens are anchored firmly against the lake bed to kill grown shoots and prevent new sprouts, but screens must be removed each fall to clean off sediment that encourages rooting. Buoys can mark identified colonies and warn boaters to stay away. Bottom screens may exacerbate a milfoil population once removed, because Eurasian water milfoil will readily re-colonize the bare sediment.
Whenever possible, milfoil control sites should become customized management zones. For example, milfoil removal by harvesting can be followed by planting native plants to stabilize sediments against wave action, build nurseries for fry, attract waterfowl, and compete against new milfoil invasions.

Chemical Control:

 Herbicide treatments are commonly used to control Eurasian water milfoil. While no herbicide treatment is completely selective for milfoil, timing treatment early in the spring as soon as water warms helps limit unintentional harm to native plants. Herbicide treatments are most effective combined with vigilant post-treatment monitoring and non-chemical controls such as hand-pulling milfoil as it returns. When used carelessly, chemical treatments can be disruptive to aquatic ecosystems, not selective in the vegetation affected, and can cause more harm than good.

Biological Control:

 Eurhychiopsis lecontei, an herbivorous weevil native to North America, has been found to feed on Eurasian water milfoil. Adult weevils feed on the stems and leaves, and females lay their eggs on the apical meristem (top-growing tip); larvae bore into stems and cause extensive damage to plant tissue before pupating and emerging from the stem. Three generations of weevils hatch each summer, with females laying up to two eggs per day. It is believed that these insects are causing substantial decline in some milfoil populations. Because this weevil prefers Eurasian water milfoil, other native aquatic plant species, including northern water milfoil, are not at risk from the weevil's introduction. Twelve Wisconsin lakes are currently part of a two-year DNR project studying the weevil's effectiveness in curbing Eurasian water milfoil populations. The fungus Mycoleptidiscus terrestris is also under extensive research.

Social Benefits 

Just as with a rural forest, an urban forest provides many benefits. Numerous studies have been done about the social 
and psychological benefits of “green” in urban environments. The findings of the studies make a strong case for the 
importance of urban forests. Urban public housing residents who lived in buildings without trees and grass nearby were 
asked about how they cope with major life issues. They reported more procrastination and assessed their issues as more 
severe than residents with green nearby. 
A study done with children with Attention Deficit Disorder (ADD) found that children with ADD were better able to focus 
and concentrate after playing in natural, green settings, than in settings where concrete was predominant. 
Apartment buildings with high levels of greenery have been shown to have approximately half the number of crimes 
than those with little or no greenery. The results proved true for both property crimes and violent crimes. A similar study 
found that residents living in areas without nearby nature reported more aggression and violence than those living with 
nearby green. In addition to these specific studies, access to nature also provides humans with other social benefits. 
Parks and other green spaces provide a space for people to play, walk, jog, birdwatch, or just sit quietly. These activities 
are good for our physical health in a society that is increasingly sedentary. It is also good for our mental health by 
providing a place to unwind. Trees also reduce noise levels. 

Economic Benefits 

The economic benefits of urban forests are increasingly being documented. Economics often becomes the language 
used when it comes to urban forest management. Budgets of municipalities must cover an array of services, and the 
benefits of an urban ecosystem must often be proven to secure funding. In a study that considered the costs and 
benefits of municipal forests in five U.S. cities, the researchers found that for every dollar spent on trees, the benefits 
returned were worth from $1.37 to $3.09. A little math tells us this is clearly a good investment. 
Trees save money through reduced energy costs. Cities create what is referred to as a heat island. The concrete, asphalt, 
buildings, and other surfaces absorb and hold heat from the sun. During hot summer days, cities can be five to nine 
degrees warmer than surrounding areas. Shading, evapotranspiration, and wind speed reduction provided by trees help 
conserve energy in buildings. A study conducted in Minneapolis, Minnesota, showed that trees placed in the proper 
location can reduce total heating and cooling costs by eight percent. 
Homeowners not only reduce costs of heating and cooling their homes, but increase the value of their property by 
planting trees. Research suggests that property value can increase three to seven percent when trees are present. Trees 
also make homes and neighborhoods more desirable places to live. One economic benefit that urban trees can provide, 
but often don’t, is one based on products. Municipalities and tree services across the country have come up with ways 
to use the wood that is cut from an urban forest. Products range from specialty furniture, to musical instruments, to 
lumber for park shelters, to artwork. The income from selling products from the wood of trees being removed could be used to defray the cost associated with the removal, making trees an even better investment. 

Trees and Climate Change 

The information about how trees impact climate change is taken from the National Arbor Day website 
http://www.arborday.org/globalwarming/treesHelp.cfm, and the American Forest Foundation website 
www.americanforests.org/resources/climatechange/ 
Deciduous trees, planted on the west, east and south sides, will keep your house cool in the summer and let the sun 
warm your home in the winter, reducing energy use. 
Just three trees, properly placed around a house, can save up to 30% of energy use. 
Trees or shrubs planted to shade air conditioners help cool a building more efficiently, using less electricity. A unit 
operating in the shade uses as much as 10% less electricity than the same one operating in the sun. 
Neighborhoods with well-shaded streets can be up to 6–10° F cooler than neighborhoods without street trees, reducing 
the heat-island effect, and reducing energy needs. 
Shaded parking lots keep automobiles cooler, reducing emissions from fuel tanks and engines, and helping reduce the 
heat-island effect in communities. 
Trees absorb carbon dioxide (CO2), the primary gas causing global climate change. Trees retain the carbon (C) from the 
CO2 molecule and release oxygen (O2) into the atmosphere. The retained carbon makes up half the dry weight of a tree. 
Forests are the world's second largest carbon reservoirs (oceans are the largest). Unlike oceans, however, we can grow 
new forests. One acre of forestland will sequester between 150 - 200 tons of CO2 in its first 40 years.