Trends in Trends

From The Changing Illinois Environment: Critical Trends, 1994, Summary Report of the Critical Trends Assessment Project

Several "trends in trends" are generic to all Illinois ecosystems. Findings suggest that, overall, pollution is down, in many cases dramatically. Rates of wetland loss have slowed, forests are coming back, and active citizen groups are at work restoring prairies and helping protect surviving natural areas.


Habitat fragmentation and other physical changes have surpassed conventional pollution as threats to ecosystem functioning. Even though pollution is being reduced in Illinois, most of the state's natural systems have not responded with anything like their former vitality, and the burdening of the atmosphere with carbon dioxide since industrialization may affect the climate for decades to come.

Illinois may be said to be moving away from complex natural systems toward less diverse ones, from stable systems toward unstable ones, from native species toward non-native ones, from integrated systems toward fragmented ones, from self-sustaining systems toward managed ones, and from preserved systems to restored or created ones.

Illinois is also moving away from systems constrained by ecological forces toward ones constrained by social forces (such as regulation). These social forces are evolving too, moving from private decision-making about resources toward shared private-public decision-making, and from an ethic of resource consumption toward one that emphasizes efficiency, reuse, and pollution prevention.


Illinois' industrial century ended roughly with the 1960s. Since then, Illinois streams have become chemically cleaner and the air in its cities more breathable. Old mines and factory sites are being cleaned up, if slowly; new ones operate under regulations meant to make future cleanups unnecessary. Illinois factories use fewer environmentally problematic materials, or use less of them, or dispose of them more responsibly.

Pollution has changed since it was first recognized as a public issue in the last century. In Illinois' industrial era, pollution tended to be local in its extent and concentrated in form; since the 1960s pollution is increasingly dispersed and dilute ("downstream" now refers to the atmosphere as well as streams), and it poses uncertain risks to human health and ecosystem function. Trends in the newer, chemically more exotic pollutants are harder to measure, in part because they have only recently been recognized as pollutants. (PCBs and CFCs once were thought to be environmentally safe.) So while Illinois is getting indisputably cleaner in some ways, it may also be getting dirty in new and unrecognized ways.


While the environmental history of Illinois is popularly understood as the degradation of unsullied systems into polluted ones, the larger trend has been the replacement of a complex natural environment with an ever-simpler one. Dams, levees, and channelized streambeds simplify the complex seasonal ebbs and flows of surface waters. Fish censuses show populations skewed toward the few tolerant species (native and exotic) and away from the several species valued for sport or essential to ecosystem function. Rural row-crop lands have been called a "grain desert" because of their paucity of wildlife and plant habitats.

Illinoisans used to be dependent on complex local ecosystems for sustenance, using fairly simple systems of gathering; now they rely on fairly simple ecosystems--plant monocultures of various kinds and factory-style animal production--gathered by very complex economic systems. The farms of the Midwest, for example, are a drastically simplified version of the grassland ecosystem they replaced, as prairies that grew as many as one hundred species of plants were replaced by fields growing a half dozen.

Illinois still boasts an impressive range of habitat types. But complexity lingers mainly in habitats only marginally of use to humans, such as river bottomlands, swamps, hillsides, and bogs. As is noted elsewhere in this report, high-quality wetlands, forests, and prairies in Illinois tend to be very small and thus vulnerable to changes in their immediate environment.

As niche environments disappear, niche species dependent on them disappear as well. The result is a trend toward a generic Illinois environment populated mainly by "generalist" species able to exploit simplified ecosystems. These species include deer, certain weeds, carp, starlings, and--one of the most successful--Homo Sapiens.


The very complexity of undisturbed natural systems tends to protect them against interlopers. But disturbed ecosystems are often vulnerable to exotic species against which native competitors have evolved no defense and whose spread is not constrained by natural predators.

According to a 1991 estimate, some 28% of the vascular plants growing in Illinois are not native but were introduced from Europe, other parts of North America, and eastern Asia. (Figure 11-1 ) At present, 17% of the fish species in Lake Michigan are not native to that body. (Figure 11-2) Many of Illinois' most agriculturally damaging insect pests migrated to the state over the last 30 years, including exotic pests and pathogens that threaten Illinois populations of such key tree species as pines and oaks. Some 25 species of exotic weeds are found in Illinois woods; the non-native plants known as velvetleaf, foxtail, and cocklebur are the three most expensive weed pests in Illinois farm fields, as measured in money spent to control them. The ring-necked pheasant, a game bird from Asia, has helped reduce populations of Illinois' native prairie chicken to some 100 birds; the zebra mussel, introduced to the Great Lakes in 1986, threatens to do the same to Illinois' native mussels.

Figure 11-2. Number of Species Introduced Into Lake Michigan Each Decade

Source: Ecological Resources, Illinois Natural History Survey, 1994

Even before humans arrived in Illinois, species mix changed repeatedly as the result of climate change, the natural spread of seed by birds and wind, and animal migrations. Problems occur when exotics reproduce exaggeratedly or otherwise out-compete native species. Many weedy exotics were introduced by state and local agencies to provide forage for wildlife or to control erosion or were widely sold in the landscape trade as ornamental plants. The Illinois DOC banned the growing of problematic exotics such as the autumn olive at its own nurseries in 1983, and now cultivates only native species of trees and shrubs that it supplies for reforestation and wildlife habitat in Illinois.


Many plants and animals are thought to need large blocks of uninterrupted habitat. Illinois surveys have found that the number of plant species found in a prairie shrinks with its size, and certain birds native to the forest interior are thought to need at least 600 acres of forest to thrive. But, as has been noted elsewhere in this report, most of Illinois' intact natural systems are quite small. Wooded parcels larger than 600 acres are as common as one per township in only a quarter of the state. All but the largest remnant prairies in Illinois--Goose Lake Prairie State Park and Illinois Beach State Park--cannot fully function as ecosystems.

The configuration of a natural forest or prairie as well as its overall area determines its viability as habitat. A study of trends in nine extant hill prairies in Illinois found that the ratio of perimeter to area increased from 1940 to 1988, leaving them more exposed to invasion by woody plants. (Figure 11-3) Illinois' secondary-growth forest is almost all edge--small plots with very high edge-to-center ratios or riparian forests that have in effect no center at all, making them more vulnerable to invasion by weedy exotics.

Figure 11-3. Decrease in Size of Nine Hill Prairies

Source: Ecological Resources, Illinois Natural History Survey, 1994


Habitat fragmentation and competition from exotic species have combined to render once-stable ecosystems less so. Lake Michigan is just one example. The decimation of the lake's natural predators by the sea lamprey in the 1950s allowed populations of their common prey, the tiny alewife, to explode. The alewife then decimated native prey fish such as the emerald shiner. The alewife in turn so proliferated that it outpaced its food supply and suffered beach-clogging die-offs in the 1960s; the die-off, in turn, starved the introduced salmonid sportfish that, having been introduced to control the alewife, had come to depend on it.


Management by humans in many cases is the only alternative to habitat and species loss in ecosystems unable to sustain themselves, and seems likely to become a trend. Managed ecosystems are hardly new to Illinois. Native Americans burned prairies to trap game, among other purposes. Indeed, one could describe the human history of the state as a centuries-long unplanned experiment in ecosystem management.

However, human management of complex ecosystems can have unnatural "downstream" effects in both literal and figurative senses. A seasonal "flood pulse," thought essential to organisms adapted to Illinois' major streams, is reduced when flood control reservoirs are built on such streams. Annual seven-day high flows recorded on the Kaskaskia River at Carlyle, for example, shrank by two-thirds after a flood control dam was built there in 1967. (Figure 11-4) Governments must now achieve by complex regulations what used to occur naturally. Current law requires that reservoirs funded by or licensed by federal agencies provide for minimum flow releases to protect the ecological integrity of downstream reaches of parent streams.

Figure 11-4. Annual 7-Day High Flow Series of the Kaskaskia River at Carlyle

Source: Water Resources, Illinois State Water Survey, 1994

Natural boundaries seldom coincide with human ones. Managing on an ecosystem basis means that resource decision-making must transcend property lines or the government jurisdictions that demark responsibility in Illinois' system of essentially local resource control. For example, agencies attempting to protect instream water flows in Illinois must do so in the face of the absence of clear regulatory authority, disputes over what water levels are appropriate, unwillingness by private users to pay for studies needed to determine such levels, and conflicts over who will monitor and enforce mandated withdrawals.


The ultimate managed ecosystem is one that is created by humans. Illinois has much experience with artificial ecosystems, although much of it was acquired inadvertently. The Illinois Department of Conservation has been building wetlands for wildlife since the 1940s. Various government farm and game programs provide incentives for private landowners to restore wetlands (mainly for waterfowl) or to improve water quality; still others have been built for stormwater storage. In all, Illinois in 1992 had some 330,000 acres of created wetlands. (That figure includes farm ponds and other manmade lakes.)

Illinois boasts several examples of restored tallgrass prairies, products of a labor-intensive process that includes growing seeds in greenhouses, hand-planting of sprouts, and the careful control of non-native invaders. Attempting to create a wetland from scratch is no less difficult. Few native species are near enough to most Illinois sites to colonize new sites naturally, and because wetland plants often have very specific requirements in soil pH and hydrology, only about 40% of the species planted in a created wetland can be expected to grow even under intense management. Research underway at the Des Plaines River Wetlands Demonstration Project--450 acres of abandoned farm fields and gravel pits developed as a site of controlled experiments--may eventually improve the design and management of wetlands. Most experts agree that ecosystem creation, while a desirable alternative to the destruction of extant natural systems, has yet to prove itself as a substitute for the preservation of such systems.


In some respects humans already have become so ecologically dominant in Illinois that it is impossible to draw clear lines separating natural systems from the social, economic, technological, and political systems that influence them. Rates of soil erosion, for example, appear to vary with how much land is planted in which crops, which in turn is determined by grain prices and U.S. government crop set-aside programs.

As natural systems are more and more affected by human activity, unnatural systems--economic and technological systems, environmental laws, government incentive programs--will become more and more important. Since World War II, social trends (such as suburbanization), economic trends (such as the shift from a manufacturing to a services economy), and political trends (such as the spread of "green" politics) have had a profound environmental impact in Illinois. Understanding the long-term trends in the Illinois environment thus means understanding more than just ecological trends.

One unambiguous trend over the past 20 years is the increasing number of public programs to moderate the human impact on the environment. (Figure 11-5) Twenty-two state and federal laws affect wetlands in Illinois, among them requirements that new wetlands be created in certain cases as mitigation for natural wetlands destroyed by development. The Illinois Forestry Development Act offers incentives for land owners to convert certain farm fields to forest; these incentives are expected to have as marked an impact on the rate of reforestation as climate change did in the past.

Figure 11-5. Number of Environmental Laws Adopted Over Time

Source: Waste Generation and Management, Hazardous Waste Research and Information Center

Environmental laws serve two broad ends--pollution control regulations and natural resource preservation and management. To achieve them, a wide range of means have been adopted, from "command and control" regulations to financial incentives and voluntary programs.

Regulations. The European occupation of Illinois began more than 300 years ago, but the significant body of law affecting landfills, mining, industrial wastes, groundwater protection, exotic species control, forest conversion, and so on date from the last 30 years.

During this period, resource regulation has had some dramatic successes in Illinois. Trends toward improved visibility at weather stations at Chicago's O'Hare Airport--improvements that run counter to trends in some downstate cities--may be due to more stringent pollution controls on industry in that part of the state. Fewer than 100 doublecrested cormorants were observed in the Illinois and central Mississippi river valleys between 1966 and 1973; in the fall of 1992, 5,195 birds were counted along the Illinois River alone, part of a continental population recently enlarged in part because of federal bans on the insecticide DDT and the phase-out of leaded gasoline.

In general, the constraints on the exploitation of Illinois' natural resources have been economic rather than regulatory. But the economics of resource use increasingly are complicated by regulation, and vice versa. The federally-mandated Toxic Release Inventory compelled Illinois companies to catalog how many environmentally problematic (and expensive) materials were being thrown away; the information induced many firms to reduce emissions in their own economic interests. Industries whose waste streams are not tightly regulated have not reduced waste volumes as much as industries subject to stricter regulation.

Natural resource laws. Until recently, government policy at all levels in the U.S. addressed the consequences of environmental change mainly by encouraging it. The draining of wetlands via state levee-building and drainage laws in the 1870s and 1880s is perhaps the most conspicuous example; under terms of the federal Swamp Land Acts of the mid-1800s, the State of Illinois gave wetlands to counties for the latter to sell, proceeds being used to fund local drainage projects.

Laws to protect natural resources began to be passed in Illinois in the 1960s. The Illinois Nature Preserves Act (later amended with the Illinois Natural Areas Preservation Act) was adopted in 1963. The state's Endangered Species Protection Act took effect in 1972. In 1987 the state enacted the Groundwater Protection Act, a prevention-based approach aimed to protect groundwater as both a public and private resource. In 1989 Illinois enacted the Interagency Wetland Policy Act, which set a goal of no overall net loss of existing wetlands, and further directed state agencies to not only preserve and enhance existing wetlands but to create new ones where feasible.

In a state with a laissez faire tradition, however, public authorities are empowered to aggressively manage only those few lands owned by government. Public programs tend to affect land management indirectly (if substantially, in the case of federal agricultural policies). State of Illinois programs are generally limited to the provision of technical and financial management assistance to land owners.

Private hands will continue to fashion Illinois' de facto natural resource policy for the foreseeable future. Some 90% of Illinois forests and nearly all of its farmland is privately owned, as are its mineral deposits. On average, only 15% of the banks of Illinois' major streams (unlike most levees) are publicly owned; that ratio varies across the state, from a high of nearly 40% in the Fox/Des Plaines basin--due mainly to that area's forest preserve system--to only about 6% in the far southern Little Wabash drainage.

Economics. Future pollution control efforts will likely rely less on command-and-control regulations and more on economic incentives. This trend is dictated as much by the high cost of applying the former to large numbers of sources (such as automobiles) as by the high costs of complying with them.

There is already evident an alternative trend among firms and individuals toward more effective use of resources through pollution prevention, reuse, and various efficiency improvements. Municipalities and individuals have also reduced their waste streams. Recycling is growing (Figure 11-6) and significant parts of the reductions in consumption of fossil fuels in Illinois are owed to efficiency improvements. Reduced waste streams generally mean reduced stress on the environment, although the magnitude of these reductions is hard to measure.

Figure 11-6. Recyclable Materials Collected and Marketed from the Champaign Area 1978-1992

Source: Waste Generation and Management, Hazardous Waste Research and Information Center, 1994

Technology. Arguably technology is a more profound influence on Illinois environmental trends than even law. Since the 1920s, for example, new farm technologies in the form of labor-saving equipment, hybrid plant varieties (especially of corn), artificial nitrogen, and chemical pesticides have transformed agriculture, and with it 80% of Illinois' surface. New methods compensated for the inability of Illinois soils to sustain themselves in the face of soil compaction, erosion, and the depletion of soil nutrients and organic matter.

In the future, the genetic manipulation of plants or nitrogen-fixing bacteria might lead to dramatically lower use of nitrogen fertilizers. High-protein grasses capable of fattening cattle in pasture might spur a switch of land out of row-crop cultivation. Computer-sensed irrigation monitors promise new economies in groundwater use.

Trends in technology off the farm will be crucial as well, mainly in the areas of energy use, water efficiency, and pollution prevention and control. More efficient internal combustion engines have already allowed Illinoisans to enormously increase their vehicle miles traveled in the 1980s without proportionate increases in emissions.

Technology seems less likely to effect significant changes in land use, which in some ways has surpassed conventional pollution as the major process affecting ecosystem integrity in Illinois. New communications technology may enable more people to work from physically disparate sites and so reduce some of the transportation costs of sprawl, for example, but by eliminating distance as an aspect of job choice it is just as likely to add to the pressure to convert now-remote farmland to urban use.

Public opinion. Public opinion is a crucial factor in democratic societies that ultimately make their own environmental laws. Consensus on environmental values will probably always be elusive in a state as socially diverse as Illinois. Whether a stream is "clean" or "dirty" depends on whether one is drinking from it, fishing in it, boating on it, or flushing away factory wastes with it. Private resource owners may or may not share the priorities of public resource agencies, or indeed each other. A survey in the 1980s found that owners of large tracts of forest in Illinois were most interested in income from timber sales, but that private owners of the more typical small tracts managed their holdings for aesthetic value or as wildlife habitat.

Problems also arise when the culture's deep-rooted customs clash with more recent environmental consciousness. For example, the postindustrial sprawl of people across the Illinois countryside is an important trend with implications for air quality, energy consumption, and farmland preservation. This is why it is nearly universally decried by environmentalists and land use planners. However, many Illinoisans still only a generation or two from the small town want to recreate that environment in a new urbanized context in spite of its collective environmental cost. Zoning laws have not slowed conversion, whether via "urban villages" (self-contained developments unconnected to existing towns), the conversion of large farms into "farmettes," or one-house "subdivisions" platted to evade zoning restrictions in agricultural areas.

Public perceptions of the environment eventually inform public policy. Those perceptions vary from person to person, however, so that consensus becomes difficult to achieve. The condition of a woods will be judged differently by a bird watcher, a logger, a hunter, a nearby homeowner, a local tax official, and a resource manager, yet each judgment in its context can be valid. A commuter driving home may find immensely satisfying the view of a forest fragment that an ecologist perceives as a degraded forest. The standards of the commuter--that a forest be green and that it be visible from the highway--are radically different from those of the scientists who measure it in terms of species diversity, mortality rates, and so on.

As in much of the U.S., public support for environmental regulation in Illinois may be broader than it is deep. The environment that most Illinoisans know is increasingly artificial and--compared to presettlement Illinois--less and less "Illinoisan." Increasingly sedentary lifestyles and air conditioning mean not merely that people stay indoors but that they seal off their houses from the outside world. This isolation from the experience of the natural means that people live in one Illinois (one that is manicured and largely exotic in origin) and venture into a second Illinois (one that survives in remote nature preserves or state parks) as they might visit a museum or zoo.

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