Long-term study finds that nutrient enrichment of headwater stream disrupts food web in unexpected ways

Human activity is increasing the supply of nutrients, such as nitrogen and phosphorus, to stream systems all over the world.The conventional wisdom—bolstered by earlier research—has held that these additional nutrients cause an increase in production all along the food chain, from the tiniest organisms up to the largest predators.A long-term, ecosystem-scale study by a team of University of Georgia researchers, however, has thrown this assumption into question.

The researchers—a team from the UGA Odum School of Ecology and department of entomology in the College of Agricultural and Environmental Sciences—found , unexpectedly, that while nutrient enrichment did indeed cause a steady increase in the production of organisms lower on the food chain, organisms at the top of the food chain did not benefit.

Their study, “Long-term nutrient enrichment decouples predator and prey production,” published this week in the early edition of Proceedings of the National Academy of Sciences, was funded by the National Science Foundation.It documents the effects of long-term nutrient enrichment of a headwater stream in a forested area at the Coweeta Hydrologic Laboratory in North Carolina.For the first two years of the study, the results were as expected: the production of both prey (the organisms low on the food chain) and predators (in this case salamanders and macroinvertebrates) increased.But with continued addition of nutrients, things began to change.While the prey continued to increase at the same rate, the production of predators leveled off, signifying a ‘decoupling’ of the typical relationship between predators and prey.

Maintaining patterns of energy flow between predators and prey is a critical aspect of healthy ecosystems. “What we found was a dead end in the food chain,” said Amy Rosemond, assistant professor at the Odum School, and one of the lead researchers.“This is the first time we’ve seen this kind of trophic decoupling, or break in the food chain, between the levels of prey and predator on this scale.This kind of disruption of the food web wasn’t on anyone’s radar screen before now.”

In this instance, Rosemond explained, the break was driven by the traits of the various prey species that inhabit the stream system.Some of these species were better able to take advantage of the extra nutrition than were others.After the first two years, the nutrient enrichment began to favor the growth of large-bodied prey, such as the caddisfly, Pycnopsyche spp., over smaller organisms.These large-bodied prey were simply too big for the stream’s predators to consume; hence, they were unable to capitalize on the increase in available food.

John Davis, who conducted the research as part of his Ph.D. dissertation, said that the work has global implications.“Nutrient enrichment is a global threat to the health of freshwater ecosystems,” he explained.“However, our understanding of its effects is limited.Our experimental results varied substantially from the few other large-scale experiments, which suggests that ecosystem-level responses to nutrient enrichment are largely context-dependent.This is important because humans are increasing nutrient loading rates to a diversity of ecosystems, but our understanding of their effects is based on only a small number of ecosystem types.”

Rosemond said that their results point to the need for more research, especially large-scale, long-term studies in a variety of ecosystems.Davis agrees.“It took over four years for nutrient enrichment to decouple predator and prey production within these headwater streams,” he said.“But most ecological experiments are limited to time scales of weeks to months.”

And the need to understand the effects of nutrient enrichment continues to grow more important. According the Environmental Protection Agency, the health of 47 percent of lakes and 45 percent of streams in the U.S. is impaired, with excessive nutrients a significant source of that impairment.Nutrient inputs to lakes and streams are likely to continue to increase globally from fertilized agricultural and suburban lands and from human and animal wastes that enter aquatic systems from treated sewage, septic tanks, or run-off from land.Furthermore, headwater streams, like the study stream in Coweeta, may account for as much as 73% of all stream miles.These headwater streams are the ‘feeders’ of larger rivers, so their response to nutrient enrichment likely affects downstream systems as well. But long-term effects of nutrients have not been previously tested in these systems.

“Without more accurately assessing the long-term effects of nutrients on a diversity of ecosystem types,” Davis concluded, “we won’t be able to adequately predict how global ecosystems are going to respond to chronic nutrient enrichment.”

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Leaf mulching and fertilizer: A back-saving, soil-enriching way to deal with fallen leaves

(ARA) – As Mother Nature adorns the trees in your yard with riotous reds, vibrant yellows and exotic oranges, you can easily get swept up in the romance of the season – until those leaves turn brown, drop from the branches and litter your lawn. Then you start to think of the hours of backbreaking raking work ahead of you.

This autumn, why not try working with Mother Nature by mulching those leaves instead of raking, bagging and condemning them to a landfill?

Leaf mulching is a time-saving, environmentally friendly way to deal with fallen leaves. Plus, if you live in a community that has cut back on collection services due to the economy, mulching can solve your dilemma of what to do with the leaves littering your lawn.

“It doesn’t make sense to rake leaves and bag them, just to have them end up decomposing in a landfill,” says Dr. Phil Dwyer, senior scientist at The Scotts Miracle-Gro Company. “Leaf mulching recycles a natural resource and enriches the soil of your lawn for free.”

In fact, turf benefits by receiving more nutrients when you mulch fall leaves back into the lawn instead of raking them, according to a study by Michigan State University turfgrass researcher Thom Nikolai and ScottsMiracle-Gro scientists. Recycling fallen leaves saves time and money, adds nutrients to the soil, speeds spring greening and reduces weeds.

Here’s how to recycle this fall’s crop of fallen leaves:

* Remove the grass catcher from your lawn mower. Mow over the leaves on your lawn. Repeat until they are reduced to dime-sized pieces.

* Mow until you see about half an inch of grass through the mulched leaf layer.

Any kind of rotary-action mower will do the job, and all kinds of leaves can be mulched. Throughout the season, you can chop up to 18 inches total of leaf clutter with several passes of the mower. Having a somewhat thick layer of mulched leaves is okay as long as you can still see the green grass blades poking through. As leaf bits settle into the ground, microbes and worms get to work recycling them.

Once you’ve enriched your soil with leaf mulching, don’t forget that fall is the best time to feed and seed your lawn. A few simple steps can help ensure that your lawn will be strong next season and beyond:

* After mulching, feed your lawn with Scotts Turf Builder WinterGuard fall lawn fertilizer to help build strong, deep roots for a better foundation and a more robust lawn next year. The nitrogen in the fertilizer will also help the mulched leaves decompose faster. Be sure to sweep excess fertilizer off hard surfaces like driveways and sidewalks.

* After feeding, spread seed where needed. To reseed your bare spots, dig up bare areas, mix in compost, sow your seeds and cover with more compost. If the weather is dry, keep the seeded soil moist until new grass begins to grow. Seeding autumn bare spots will thicken the lawn and make it more resistant to future bare spots.

To learn more about leaf mulching and autumn lawn care, visit www.scotts.com.

Courtesy of ARAcontent

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For gorgeous grass next season, start with soil, end with seed

(ARA) - Summer is winding down and soon it will be time to drain the gas from the lawn mower and safely store the string trimmer. You may feel like summer yard work is done for another year. But don’t turn your back on your lawn just yet.

Take care of some essential lawn chores this fall and you’ll reap the rewards next spring – in the form of a lush, healthy, beautiful lawn. In fall, lawn grasses need to become especially strong as the weather cools. Give them some TLC now, and your lawn will reap the benefits over the winter and into next spring. During the fall, your lawn is getting ready to go dormant for the winter. Your grass will rely on its roots throughout the winter season to obtain nutrients until spring.

Following these five (surprisingly fast) simple steps will ensure a sensational start to lush lawns next spring.

1. Start with the soil and aerate

The healthier your soil is the healthier your grass will be. Good, aerated soil will make room for water, nutrients, air and roots to move with ease. Aerated, healthy soil will hold water like a sponge, but at the same time promote drainage. Aerating also creates a good environment for the micro-organisms, worms and other life forms necessary for healthy turf. Without good soil you will find yourself doing lots of weed control and over-fertilizing.

2. Don’t delay dethatching

Thatch is the layer of dead grass that settles in between the soil surface and the green foliage of the grass. Too much thatch interferes with nutrient and water absorption. To gauge thatch’s thickness, take a 6-inch-deep plug of sod and soil from the lawn and measure the thickness of the packed thatch. If your thatch layer is more than 1/2 inch thick, your grass will struggle to grow.

3. Supply soil conditioners

Also called soil amendments, soil conditioners added to soil improve plant growth and overall health. Soil conditioners are not fertilizers, but they do improve soil’s drainage and some will also increase the water holding capacity of your soil.

4. Sow your seeds

Sowing grass seed will increase turf density and improve the overall health and appearance of your lawn. Seeding in the fall helps the lawn recover from heavy summer traffic and it influences the lawn's look for the following spring. A dense lawn is also the best natural defense against weed and insect damage. For a wide variety of grass seed choices specifically formulated for your geographic region visit www.outsidepride.com.

An increasingly popular addition to backyard beauty is planting wildflowers instead of grass in hard to maintain, problem spots, like slopes and banks. Outsidepride.com offers a wide variety of blends for nine areas of the country, from the rainy Northeast to the dry Southwest. Adding wildflower seed this fall to your backyard will add beauty and diversity to your landscape next spring.

5. The easy way is the better way

When it comes to labor intensive fall lawn chores like aerating, dethatching, and soil conditioning, brute force isn’t necessarily the best, most efficient way to get the job done. You could rent a core aerator to pull up finger-sized cores of soil, but it takes a strong back and plenty of time to manage the heavy equipment. If your lawn is small enough, you can do the dethatching job using a thick-bladed thatching rake. But bigger lawns call for a power thatching mower. Soil conditioning is easier, yet still time-consuming.

Try a labor-free, easy, all-natural option that’s a liquid product, like LazyMan Liquid Gold. You can tackle the tasks of aerating, dethatching and soil conditioning with a hose-end sprayer in a matter of minutes.

Non-toxic and all natural, LazyMan Liquid Gold’s polymers penetrate hard soil and alternately attract or repel water molecules, opening pathways to allow free passage of moisture and nutrients. A brew of microbes feeds on dead plant tissue in the thatch layer, reducing thatch by half with just three applications at four-week intervals. Finally, humic acids and soil fungi promote soil fertility and plant growth.

After one-step spraying of LazyMan Liquid Gold, you’ve already accomplished three essential fall lawn care tasks. Now, all that’s left to do is seed and feed.

By following these simple lawn care practices in the fall, you can put your lawn to bed and sleep easily knowing that when your lawn awakens from winter it will be healthy and super-charged for spring. To learn more about lawn care, visit www.outsidepride.com.

Courtesy of ARAcontent

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Create Your Own Salad Garden

(NAPSI)-The current economy is fueling a grassroots hobby and a healthy money maker: vegetable gardening. One major seed company says a $10 investment can produce up to $1,500 worth of vegetables. The U.S. Department of Agriculture says vegetables are important sources of nutrients that help maintain healthy blood pressure and reduce cholesterol levels.

"Vegetable gardeners may become the most popular people in your neighborhood," says Bayer Advanced garden expert Lance Walheim, co-author of "Vegetable Gardening." "Growing your own veggies lets you create your own salad or side dishes that taste great."

Here are some tips to help you get started:

Choose your vegetables: What kind of veggies or salads do you like to eat? Options include head and leaf lettuces, spinach, parsley, asparagus, peas, carrots, corn, broccoli, eggplant, tomatoes, beans, cucumbers, okra, peppers, carrots, beets, sweet potatoes and celery.

Let the sun and soil be your guide: Most vegetables need six to eight hours of direct sun daily and well-drained soil.

Prepare the soil: Contact your local cooperative extension about soil testing, then till in ample organic matter and other recommended amendments, including fertilizer.

Lay out planting beds: Use string to mark off the individual rows of vegetables you'll plant. Rows that face east to west will get the best sun exposure.

Plant with the seasons: Contact your local cooperative extension office for a local planting calendar and for tips on locally adapted and pest-resistant varieties.

Use organic mulch: It helps keep the weeds out. Weeds compete for nutrients and may harbor pests and diseases.

Monitor for pests: Destructive insects such as Japanese beetles, aphids and hornworms like veggies, too. Bayer Advanced™ Complete Insect Killer for Gardens kills more than 100 different pests. Spray it on the upper and lower leaf surfaces, stems and branches. Be sure to read and follow label directions. Visit bayeradvanced.com for more details and for other products that will prevent insects from eating your vegetables.

Water and fertilize: Vegetables need consistent water and nutrients.

Enjoy the bounty: Pick often and share the wealth. Many vegetables will stop producing if not harvested often.

If you don't have adequate space for vegetable gardening, Walheim says you can always start small by growing vegetables in containers. A container for vegetables can be as simple as a bushel basket, ceramic pot or a planter box.

Vegetables are an important source of nutrients.

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