A summer meadow.
Grasslands originally covered about 42 percent of the world's land surface -- now largely under cultivation. The world's grasslands are characterized by low rainfall (10 to 30 inches per year), high evaporation, periodic severe drought, and rolling-to-flat terrain. In New York State where rainfall exceeds 30 inches annually, upland meadows persist only where grazing, periodic mowing, or fires prevent the invasion of woody growth. Meadowland is shrinking in New York. The state is now 61 percent forested with more than a million acres having completed their return from abandoned pastures to forest land in just the past 15 years.
A Salad to Hide In
Let us begin with a closer look at what makes up a natural meadow and how it works. We can envision our meadow as a large live-in salad in which the inhabitants work at not being eaten. Our salad bowl is the soil made fertile by the constant recycling of nutrients from the plants eaten by animals above to the organisms of decay beneath the surface. As in all ecosystems, the meadow is dependent on an outside source of energy -- from the sun -- which is transformed to sugar energy in every blade of grass and forte (broad-leaved herb).
In a forest the layers -- herb, shrub, understory, and canopy -- are distinct and obvious. But walking through a waist-high meadow, we can scarcely see our knees let alone discern the plant layers that hide them. Certainly the most obvious plants are the grasses -- tough, resilient, no nonsense work plants unlike the much less numerous fragile looking, showy broad-leaved beauties that decorate the meadow. Grass can be trampled and laid upon by the grazers that browse it to the ground, and come right back for more, relying on its quick regenerative powers and huge numbers to thrive. Unlike the broad-leaved forbs, grass grows from its joints at the bottom of the plant. Thus it possesses an ability to grow hack after grazing and to right itself quickly after being flattened by feet or wind. Tough tubular stems enable tall prairie grass, weedy phragmites, and cultivated corn to grow 12 or more feet tall. Grasses are either sod formers, like Kentucky bluegrass, developing a solid mat over the ground, or hunch grasses -- orchard grass, for example -- with spaces between occupied by fortes.
Broad-leaved herbs grow from the extension of their tops and do not compete well when heavily grazed. Unless a lateral bud can resume the upward growth, a new shoot must start again at the base of the plant, where less space and light exist. In order to ensure their survival nature makes many of these broad-leaved plants unpalatable. Queen Anne's lace, most of the mints, pepperweed, and tansy all taste terrible to most grazers. Teasel, thistle, and mulleins possess spines or matted hair to avoid the hungry, while milkweed is filled with a bitter rubbery sap.
Who Eats Whom?
In this fertile shadeless environment, every square inch of soil could be covered by pants. But in the relentless competition for the available space and light and moisture among the plants, and the constant grazing of herbivores, the vegetation potential is never fully reached. When we think of grazers, the large and obvious deer, woodchuck, and rabbit first come to mind. A good rule in nature, however, is that the larger the animal (or plant) the fewer of them there are. Even if we add the far more numerous meadow mice, we are still considering only a tiny fraction of the herbivorous community. Crickets, leaf hoppers, grasshoppers, caterpillars, and aphids are only a few of the many thousands of kinds of insects at work on the leaves and stems in the typical meadow. Insects are the meadow's real grazers.
The plants have an unwitting ally in their struggle for survival in the predaceous animals in the meadow community. Their food and energy also comes from plants in the food chain -- from plant to plant eater to animal eater, but the carnivores help keep the plant supply far in excess of the herbivores, chewing. Hawks and foxes are among the most familiar predators. Although we seldom think of it as such, a tree swallow swooping midair on a midge, or a meadowlark tearing apart a grasshopper is as predaceous as the more obvious eating habits of assassin bug, jumping spider, or ambush bug.
Life and Death Among the Roots
The lowest layer in a grassland is perpetually hidden from our view -- the roots. Half or more of the grass are roots which extend downward five feet or more for often scarce water. During the winter when the above ground parts die, almost all the plants are roots. Roots store food reserves and provide minerals as well as water to parts above. But life where is no more tranquil than aboveground. The main energy source below ground, unlike the living plant material above, is dead plant and animal matter and feces. These are broken down by bacteria, fungus, and protozoans. While parasitic nematodes and root-feeding insects consume living plants, far more significant are the fresh litter (or detritus) feeders such as the earthworms, pst worms and millipedes. They ingest large quantities of organic matter, mixing, aerating and enriching the soil as they do so, and digest out some of the bacteria, fungus, protozoa, and other tiny invertebrates. The most abundant soil creatures are the eight-legged mites and springtail insects which shrive on the microscopic fungi they separate out from the plant litter they eat. Spiders, insects, mites, and nematodes are the most common predators. A few kinds of soil fungi have evolved from plant litter consumers to predators -- turning the tables on the tiny fungi-eating soil animals. Nematode-trapping Hyphomycetes act like flypaper. Most unusual is a rabbit-snare type of trap in which a nematode passing through a ring of fungi cells triggers in one-tenth of a second the inflation of ring cells constricting and holding the nematode until the fungus can penetrate and digest i$B body.
How Much Mulch?
Down on our hands and knees we can see the ground layer in the meadow characterized by reduced windflow and decreasing light intensity as the grasses grow taller. Ground hugging and low-growing plants like the mosses, wild strawberries, cinquefoils, violets, and dandelions do their most active growing and reproducing before they are left behind by the tall-growing grasses and fortes. The white and red clovers are especially important low growers in the meadow since these legumes enrich the soil below with the nitrogen-fixing bacteria nodules on their roots.
Mulch is by far the most important component of the ground layer -- dead and decaying leaves and stems. In a natural grassland, three or four years pass before mulch completely decays. In the meantime, just as in our gardens, mulch helps retain soil moisture by promoting infiltration rather than runoff and by reducing evaporation. An accumulation of mulch is important to the maintenance of a healthy grassland. Since mowing, grazing, and fires reduce mulch, overexploitation can result in deterioration to weeds.
The herb layer in a meadow is the one most apparent to us. Besides the already mentioned low-growing layer most visible in the spring, the middle layer of shorter grasses and such fortes as wild mustard, black-eyed Susan, and daisy fleabane is next established. Finally by fall, the tallest grasses, goldenrods and asters overtop the middle layer.
Nature's Three Realms
Geographer Yi-Fu Tuan suggests that we should be concerned with three realms of nature: our thoughts and feelings about nature; what nature is -- the science of nature; and our behavior in and-use of mature. Summer meadows beckon our escape from civilization where we can just simply care about and enjoy nature's first realm. We need summer meadows to stimulate our curiosity about how the world works -- nature's second realm. Knowing how a meadow works will help us in nature's third realm -- becoming better stewards of our croplands -- managed meadows that feed all.
Frank Knight is director of DEC s Stony Kill Farm Environmental Education Center in Wappingers Falls. A graduate of NYS College of Agriculture at Cornell Mr. Knight has been an environmental educator since 1962.
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|Title Annotation:||reprinted from The New York State Conservationist, July 1983|
|Publication:||New York State Conservationist|
|Date:||Jun 1, 1996|
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