Grasslands are critical waterfowl nesting habitat
As the percentage of grassland in a landscape increases, so does the success of duck nests (Reynolds et al. 2000).
The Prairie Pothole Region of the United States and Canada is North America's single most important waterfowl breeding area. Dotted with millions of shallow wetlands formed by glaciers 10,000 years ago, the Prairie Pothole Region encompasses more than 250,000 square miles and supports more than 50 percent of the continent's ducks in most years. In some portions of the region, potholes and their associated prairie uplands support over 100 breeding pairs of ducks per square mile.
Grasslands in the Prairie Pothole Region
The Prairie Pothole Region is especially important to breeding northern pintails, mallards, canvasbacks, redheads, gadwall, blue-winged teal and northern shovelers. Currently, most ducks across the region have met or surpassed population goals established by the North American Waterfowl Management Plan. One exception has been the northern pintail. This grassland-dependant duck has struggled despite generally favorable water conditions over the last decade. In fact, breeding pintail populations have decreased in excess of 50 percent in the last 20 years, with little sign of improvement. Factors limiting the comeback of pintail populations over the past few years are not entirely clear, although researchers suspect that poor nest success is the leading cause of the observed decline. Pintails typically settle on the breeding grounds in areas containing shallow wetlands that usually hold water only through early summer. Unfortunately, these are also the easiest wetlands to drain and many have been lost with the expansion of cropping practices. The areas that remain are subject to increased predation and disturbance due to highly fragmented nesting cover and to spring cropping practices.
Blue-winged teal, another species that has historically relied on the grasslands of North America for breeding habitat, have experienced population fluctuations that mirror the wet/dry cycle of the northern plains. Currently, the population is estimated at nearly 6 million, slightly down from 7.4 million in 2000. However, these numbers are above the NAWMP population goal of 4.5 million.
Several million ducks and geese use the Prairie Pothole Region each spring as breeding or stopover habitat during their spring and fall migration. Regions that have experienced substantial native prairie losses, such as Iowa, still offer valuable migration habitat in early spring when the ground is frozen and drain ditches are not yet flowing. Each autumn, an estimated 8-10 million ducks and almost one million geese migrate south through Iowa, en route to warmer climes. A few, including an estimated 106,000 ducks and 138,000 geese, remain during the winter in the Prairie Pothole Region or adjacent areas. However, the Prairie Pothole Region is most crucial for nesting waterfowl.
Grasslands stand up to (and are shaped by) grazing and fire
From the Gulf Coast of Texas to the Prairie Pothole Region of the Great Plains, centuries of short-term grazing and periodic fire shaped the structure and function of grassland ecosystems. Prairie grasses are adapted to tolerate loss of plant material, and in fact respond to fire and moderate grazing with vigorous growth. Livestock and wildlife, in turn, depend on healthy grasslands for nutrition and shelter.
The ability of native grasses to thrive in the face of fire and grazing is a result of their defensive design. Plants grow from points, known as apical meristems. In grasses, these points are located beneath the soil surface. This unique adaptation protects them from disturbances that destroy or seriously damage other plants.
Properly managed grazing regimes are beneficial to livestock, wildlife and native prairie. The absence of grazing significantly decreases productivity and species diversity on prairie grasslands. Alternatively, overgrazing poses a serious threat to species diversity and habitat structure. Diversity is compromised when nonnatives invade an area, soil and nutrient loss exceed recovery rates and productivity of plant resources declines.
Some areas of the Prairie Pothole Region, where the topography is rocky and rough, have never been plowed. The primary land use on these areas over the last 100 years has been livestock grazing. Locations where native prairie exists adjacent to wetlands are some of the continent's best waterfowl nesting habitat.
In the spring each year mottled ducks, black-bellied whistling ducks and fulvous whistling ducks breed in pastures along the Gulf of Mexico coast where livestock grazing is properly managed. Grasslands of the Gulf Coast of Texas host significant populations of wintering waterfowl, shorebirds and livestock.
Because prairie grasses are adapted to fire, fire is often used as a management tool to maintain their health and productivity. Burning grasses enhances grassland vigor by increasing species diversity, reducing noxious weeds and eliminating woody vegetation. Species diversity is enhanced as grasses are given room to grow when undesirable invading species are removed. Woody plants and noxious weeds are common invaders of prairie wetlands and grasslands deprived of fire.
Grasslands benefit the economy
Grasslands contribute $78 billion annually to the U.S. economy by supporting an estimated 60 million cattle and 8 million sheep. To sustain agricultural production, grasslands must be conserved and well-managed to produce robust, resilient stands.
Abundant recreational and tourism opportunities exist in North America for the millions of visitors who spend countless hours each year in the tranquility and open spaces of grasslands. Whether riding horses on the plains of Texas or hunting pronghorn antelope in the short-grass prairie of Wyoming, there are plenty of recreational activities that benefit many.
Recreation and tourism afford economic benefits to local communities and states. Revenue generated through sales of outdoor gear, guide services, lodging and countless other activities contribute directly to the local community's economy. These transactions further create benefits by providing jobs to related manufacturing and service industries, thus creating revenue through a ripple effect across the entire region. Estimates from the National Survey of Fishing, Hunting, and Wildlife-Associated Recreation suggest almost 80 million people participated in consumptive and non-consumptive bird related recreation in 1991. Migratory waterfowl hunting alone contributed an estimated $1.3 billion to retail sales nationwide. Non-consumptive bird recreation generated $3.3 billion in retail sales revenue. These are significant benefits derived from tourism and recreation provided, to a large extent, by grassland ecosystems.
Grasslands also offer the potential to provide economic benefits from clean energy production. There is a growing emphasis in the potential for biofuels from harvested grasslands to replace practices with higher emissions. Grasslands also exist is some of the most wind-rich regions of the country. If these new sources of energy are planned so not to adversely impact wildlife populations, they could result in the restoration of more acres of grassland in areas of marginal cropland and boost struggling rural economies.
Grasslands store carbon
Atmospheric concentrations of "greenhouse gases" serve to insulate the Earth making life possible. However, increasing evidence suggests that the earth is warming at an "unnatural" rate due to the accumulation of greenhouse gases in the atmosphere from the burning of fossil fuels and the clearing of land. Atmospheric levels of greenhouse gasses such as carbon dioxide and methane have increased by 30 percent and 150 percent, respectively, since the mid 1700s when the Industrial Revolution began.
Plants and soil have extraordinary capacity to remove and store atmospheric carbon, thus diminishing greenhouse gases. Plants remove carbon dioxide from the atmosphere through photosynthesis and use it to build leaves, stems and roots. As these plant parts die, they become buried in the soil, permanently removing carbon from the atmosphere unless the soil is broken through cultivation or mined for fossil fuels. Grasslands in North America have an enormous capacity to store atmospheric carbon and mitigate the negative impacts of greenhouse gasses. In South Dakota alone, the restoration of 4 million acres of marginal cropland to grassland would remove over 500 million metric tons of carbon dioxide equivalents from the atmosphere over 80 years!
Carbon sequestration through grassland restoration offers advantages to energy companies seeking offsets by reducing risks and diversifying reduction portfolios. Because most of the carbon in grasslands is stored beneath the ground, it is not susceptible to loss from fire, drought and disease. Grassland restoration also buffers investments made in forest carbon sequestration projects in the southern United States and in the tropics.
Agricultural producers benefit from carbon sequestration by soil quality improvement, diversification of income sources and by making economic use of grass in ways that do not diminish the soil-sequestering function, like haying, grazing and biofuel harvest. In addition to the benefits of reducing greenhouse gases, carbon sequestration has the potential to develop into another economic tool to build quality soils which serves our best national and international interests in the long-term.
Grasslands serve as wildlife habitat
Historically, grasslands in the United States supported 30 to 70 million bison and similar numbers of pronghorn antelope. Large herds served as mobile communities, moving over grasslands following available forage, which varied with seasonal and climatic conditions. These huge grazing communities stimulated grass growth and diversity while discouraging woody and non-native plant invasion. Prairie grasses and soils have adapted to the disturbances associated with these grazers.
Today U.S. grasslands support an estimated 20 million deer, 500,000 pronghorn antelope, 400,000 elk, and many other wildlife species. Each species possesses a unique natural history, but all are well adapted to the rewards and challenges of life on the prairie grasslands. Waterfowl, shorebirds and small mammals are just a few non-grazers that depend on prairie grasslands. Large un-fragmented grassland areas such as Nebraska's Sandhills, the Missouri Coteau portion of the Prairie Pothole Region and the Gulf Coastal Prairie of Texas offer high wildlife habitat value.
Nebraska's Sandhills provides important nesting and migration habitat. The Prairie Pothole Region is most important to northern breeding waterfowl such as northern pintails, mallards, canvasbacks, redheads, gadwall, blue-winged teal and northern shovelers. The Gulf Coast of Texas is an important breeding area for mottled ducks, black-bellied whistling ducks and fulvous whistling ducks, with nearby bays and other coastal wetlands providing important wintering waterfowl habitat. Each of these areas provide important and unique wildlife habitat to a diverse group of species.
Grasslands conserve soil
Soil supports and sustains life. Rich with life, prairie soils of the Great Plains drew pioneers and farmers across North America in record numbers during the late 19th century and early 20th century. By the 1930s, the prairie soil, devastated by rudimentary farming practices and unyielding drought, was easily whipped up into great dust clouds prompting the beginning of an era known as the Dirty Thirties.
Today, modern farming practices that minimize soil disturbance, such as no-till farming, crop and grazing rotation and land enrolled in the Conservation Reserve Program greatly reduce impacts to soil.
Soil stores and cycles carbon, nutrients and nitrogen; degrades pollutants; and, drives decomposition. These activities are performed by the diversity of living organisms that live in the soil. Arthropods, bacteria, earthworms, fungi, nematodes and protozoa make up some of the diversity found in the soil. A single scoop of rich garden soil contains more species of organisms than can be found above ground in the entire Amazon rain forest.
Prairie soils support native and tame grasses that have extensive root systems growing deep into the earth. Native grasses of the prairie can have roots that measure up to 15 feet in length. Sod-forming roots physically anchor fragile soil during the heavy rains and high winds that are common on the prairie. Agricultural crops which are harvested and then tilled expose the soil to erosive forces leading to a loss of carbon and precious nutrients.
It is estimated that the Conservation Reserve Program alone prevents 700 million tons of soil erosion per year, simply by changing land use practices in highly erosive prairie areas. Soil is kept on the land and out of reservoirs, lakes and streams. The program is straightforward: marginal land once used for agricultural production is put back into wildlife habitat and landowners are compensated for not farming that land.
Grasslands increase biodiversity
Biological diversity ("biodiversity"), refers to a broad spectrum of types and levels of biological variation. One of the ways scientists quantify Earth's terrestrial biodiversity is by classifying vegetation into large, regional ecological units by dominant vegetative patterns, better known as biomes. These biomes include the tropical forest, savanna, desert, chaparral, grassland, temperate forest, taiga or boreal forest and tundra. Each biome is distinctive due to the amount of annual precipitation, number of frost-free days and other physical and biological factors.
The grassland biome covers about one quarter of the Earth's land surface and in North America grasslands account for about 15 percent of the continent. Ecological processes such as fire and precipitation help to maintain the unique character of grasslands. Frequent fire prevents woody plants from dominating grassland habitats, as does relatively low annual precipitation. Yearly precipitation in the grassland biome of North America falls in a gradient from west to east, with the shortgrass prairie to the west receiving up to 10 inches, the mixed grass prairie in the central portion of the continent receiving up to 20 inches, and the tall grass prairie further east enjoying precipitation of up to 40 inches per year.
Unique from most other biomes, grasslands are relatively simple in structure but rich in number of species. However, most areas of the prairie have experienced serious declines in biodiversity. Grasses have been especially impacted by decades of human induced alterations to the prairies that have allowed for the invasion of non-native species. Today, non-native grasses account for 13 - 30 percent of prairie grass species.
Loss of diversity continues as forested patches, tilled soil and woody corridors increase on the prairie landscape. Grasslands of the Great Plains once acted as a virtually impenetrable barrier between wildlife and plants of eastern and western forests. Where new deciduous forests border highways and communities, plants, birds and mammals previously unknown on the prairie now have migration corridors. Altered prairie landscapes have fostered reduced biodiversity by encouraging hybridization between species that once were geographically isolated. Such is the case with the hybridization of at least six sub-species of birds along forested tracts and new forest corridors.
Certainly, the grassland biome is much different today than before extensive alteration. But with continued persistence and action by dedicated conservation interests, biodiversity can be preserved and increased throughout the region.