WORKING GROUP SUMMARY
The following is a summary of the results of the four working groups from the Great Plains Climate Change workshop. The groups focused on resource issues in the following areas: Social, Water, Biology, and Soil. These discussions were intended to be cross-cutting and to overlap somewhat with issues covered by the other groups. To avoid duplicating discussion, the individual working group reports have been reorganized so that each issue falls under only one group. An additional category of Stakeholder Information Needs was added to capture some items common to all the groups.
The four working groups were provided a focus and asked to discuss issues related to:
Social: Vulnerability or risk of different communities in the Great Plains, social or political structures available to offset impacts, economic and political considerations for developing strategies to cope with climate change impacts.
Water: Water quantity and quality and how these may affect human and ecological conditions.
Biology: Changes in communities of plants and animals, such as invasive weeds, specialized crop or animal breeds, and pest outbreaks.
Soil: Soil erosion, soil fertility, carbon storage, and salinization.
Each group was asked to address the following questions for its resource area:
What issues are of concern in this area presently?
How might climate change affect those issues?
What coping strategies are available for dealing with climate change effects in this area?
What research is needed to understand and prepare for climate change consequences in this area?
The focus of this group was on issues concerning social resources, such as the vulnerabilities and risks for different communities in the region, existing social and political structures available to offset impacts, and economic and political considerations for developing strategies to cope with change. Changes in rural patterns of the Great Plains are a major concern for the people of this region. The socio-economic and cultural aspects of the agricultural and conservation sectors of the region are tightly interwoven and are sensitive to external market forces. Increased multi-use demands on water and public lands are resulting in conflicts over grazing licenses, use of riparian areas, declines in rangeland condition, and access to natural resources. These issues were all discussed as potential "stress factors."
Economic and Policy Issues
Farming. Market variability combined with high climatic variability affecting production can lead to even greater variability in year-to-year profits, making long-term investment more risky. Current agricultural tax policies intensify the problem. Increased climate variability would exacerbate the present stress associated with high precipitation variability. Increases in the frequency of hail and intense storms could add even more stress.
Increasing costs of production inputs such as fertilizer, pesticides and seed for specialized niche crops are increasing stress on farm enterprise profit margins. High capitalization costs for more diversified operations (e.g. incorporating livestock operations) are an additional constraint. Changes in crop or livestock production patterns regionally and globally can strongly affect the local economy. For example, expansion of beef or wheat production in South America or elsewhere would impact the market prices of the commodities and in turn affect the profitability of enterprises in the Great Plains. Climate change adds an additional layer of risk to an already vulnerable area.
Farmers who have adapted to Federal policies that have been in place for many years must now adapt to new, market-based policies. Their safety net has been cut. This change will stress the system, and climate change will exacerbate these stresses by forcing parallel adaptation to new crops and practices. Under the market-based policy global market changes will impact farmers more, making adaptation to changing climate even more difficult.
A major change in economic policy which has reached deeply into the sustainability of the agricultural sector has resulted from changes in the tax laws. It was pointed out that in the past farmers were able to "income average" for tax purposes, but this is no longer allowed. Because of the inherently high profit-variability for Great Plains farmers, the disallowance of income averaging hits them disproportionately hard. It may force them to store more grain than they would otherwise choose to, requiring additional investment in storage facilities and it might also prevent them from selling when the market is most favorable.
Although the Conservation Reserve Program (CRP) has proven to work relatively well throughout the Great Plains, some of its regulations and side effects are detrimental. Limitation of legume usage in some areas results in poor crop production due to N limitations, and reduces potential benefits to soil recovery by reducing soil carbon inputs. More flexibility in uses of CRP, such as grazing, should be considered to improve the vegetation stand (low to moderate grazing is beneficial for grassland health), and should thereby derive additional benefits. Another undesirable side effect of CRP was a decrease in rural employment for areas with a high percentage of CRP and elevated land prices. These and other issues should be considered in updating CRP.
A major concern upon which many facets of the Great Plains social structure converge is water availability, allocation and storage. Present legislation, regulations and compacts often limit the water management practices, precluding more effective use of surface and groundwater. There is a need to assess water use efficiency in the region and for water management to adapt to multiple needs. A whole-watershed approach would maximize water use efficiency and prevent conflicts among water users. Diverting water from a river just to protect a diversion or water right is not necessarily an efficient or economical use of that water. Over-irrigation with this diverted water leaches nutrients and potential pollutants into the groundwater aquifer while runoff carries nutrients, salts and other pollutants back into the river. Transfer of water from basin to basin and from aquifer to aquifer would, in many instances, allow these waters to be used for optimal returns.
Ranching. Ranchers face similar issues but are more dependent on the natural resource base. The response of rangeland vegetation to rapid climate change may include significant changes in species composition, productivity, palatability, and forage quality. Major changes could require changes in stocking levels, grazing regimes, or a shift from cattle as the primary product to alternatives such as buffalo, goats, or sheep. Changes might be so drastic as to warrant major shifts of marketed animal protein to exotics such as emu and ostrich, or to prairie rodents such as rabbits. Since the future is difficult to predict, it would be prudent and appropriate to study the feasibility of various alternatives under different climate change scenarios.
Pollution of water and air concerns regional planners and local landuse managers. Many farming, livestock, and urban wastes represent both potential energy resources and/or sources of greenhouse emissions. While these wastes represent both potential assets and liabilities for society as a whole, they may be neither valuable enough nor noxious enough for their original generator to deal with them productively. Accordingly, society might benefit by providing incentives for waste generators (or others) to convert the potential of these wastes into actual benefits.
Constraints on Agriculture Diversification
The climate of the Great Plains limits options for diversification in management, i.e. there is relatively low flexibility in planting dates and a limited number of suitable crops. However, diversification also extends to sources of production and income for households. Off-farm income is an important risk avoidance technique, especially for monoculture enterprises. Legumes can be successfully integrated in dryland crop locations, along the lines of the Australian annual legumes, both as a source of forage and as a N source to help rebuild soil organic matter. Social and lifestyle issues affect diversification, as many younger farmers lack interest (e.g., wanting free time in winter) or experience (e.g., in dealing with livestock), leading to increasing specialization in straight cash grain production systems.
Farmers do not see themselves as part of this problem. Rather, they want to help find a solution. Through diversification, farmers would be able to meet such challenges and better position themselves in the market. Diversification would also help minimize their risk by allowing them to better meet the variability that climate changes may present. What crops are more drought tolerant and more resilient to climate change variability? Are some species of livestock stronger or better able to adapt to changes? Climate change could act negatively on some diversification options, such as incorporation of summer crops (e.g. corn) into rotations because of increased vulnerability to extreme events such as hail. There might also be new opportunities for use of additional crop types because of increased temperatures, but added moisture stress might negate such positive effects. With greater climate variability, diversification of agricultural options would become even more important. The breadth of options are limited by the quality and availability of human and natural resources. If land and human resources have been pushed to their limit, areas with marginal soils rarely bring in enough income to allow for wide-scale risk avoidance strategies. Under the stress of climate change, marginal land and/or human resources will not likely be able to respond. Marginality relates both to the quality of the land and its resources and to the economic stability of the farmers/ranchers.
Rural housing development: On both the eastern and western margins of this region, grazing land is being removed from production by urbanization or being fragmented by construction of small acreage homesites (ranchettes). While not affecting a large area, this trend is significant because it occurs mainly in ecotonal strips around metropolitan areas on the eastern margin, and around the ecotonal foothill zones of the western margin of the region. Urbanization and population growth are resulting in the loss of prime agricultural land and in conflicts over water supplies along the Front Range and in the Platte River system. This trend is especially critical from a wildlife point of view.
Population issues: Urban population growth does not preclude the depopulation of rural areas. Growth also affects land and water use. For example, growth in nearby urban areas can reduce the amount of water allocated to agriculture. Relocation of a rural populace to urban areas outside of the region may occur in response to changing conditions. Lack of amenities, relative to modern urban settings, along with declining infrastructures and service sectors in rural communities, contribute to a declining rural labor force and to problems of recruiting new farmers.
The increasing regional trend toward absentee ownership acts as a general disincentive, preventing tenant farmers from making investments in the soil resource. A striking example is the interaction between social and ecological stresses in regard to reducing the amount of bare fallowing through adopting more continuous crop rotations. It was suggested that for tenant farmers, paying 1/3 of the harvest for land rental, it was more economical to use wheat-fallow, effectively paying rent on only 1/2 of the land each year, than to pay higher rental rates, with more crops harvested. The more continuous cropping would presumably yield a lower marginal return from a summer crop (e.g., corn) following wheat than would wheat after fallow. However, the reverse could be true for owner-operators, who would find the more continuous cropping, and more environmentally beneficial, systems to be more economical.
Problems with new farmer recruitment and the "graying" of the present farm population were seen as important stresses. Increased costs and reduced land availability along with changes in lifestyle, contribute to this situation. There is a growing need to secure knowledge transfer and the mentoring of new farmers, since many farms are not being taken over by the farmers' children.
Human health concerns arise in discussions of climate change. Under some scenarios increased disease vectors and pest infestations may become more prevalent in the agricultural sector of the Great Plains. Farmers and ranchers in the work-group expressed concern about the impact of disease and pests on crops and livestock.
Airborne pollutants also present important health impacts. For example, under some climate change scenarios the soil dries out, setting up a "dust-bowl" cycle. The consequent loss of vegetation on agricultural fields and open areas can make these areas more susceptible to soil erosion and blowing dust during high wind events. Drier climatic conditions would increase the incidence of fires and thereby increase the amount of smoke in the atmosphere. Air quality becomes a social issue when winds transport air pollutants across regions. For example, feedlot odors affect property values; particulate matter from transportation and agricultural operations affect health and visibility, consequently affecting tourism and recreation; drifting pesticides can affect the health of humans, animals, and crops. All of these could be intensified by a change in climate regime. Other environmental concerns that can impact air quality include nitrogen deposition, ozone, methane emissions, and visibility. Determining ozone levels of rural areas is difficult because ozone monitoring networks are concentrated in heavily populated urban areas.
Regional transport of air pollutants (and blowing dust) are affected by climate variability, and will need to be evaluated in light of the new particulate matter and ozone/visibility standards set by EPA. The new standards need to be considered when looking at various climate change scenarios.
This group addressed water resource concerns, such as water quantity and quality and the effects of both on human and ecological conditions. Concerns about water cut across all issues. Changes in water availability are felt on local, regional, national, and global scales. For example, use of river water in Colorado affects the quantity of water available to Nebraska, Kansas, and the Southwest. Water taken from the Ogallala Aquifer in Nebraska affects groundwater supplies in Kansas and Colorado. Water issues include various factors affecting water supply, demand, allocation and quality.
Water Supply
Population growth in the western Great Plains is already stressing the allocation of water resources, a condition which may be aggravated by increased climatic variability. Demand for reliable water supplies will require increased water storage, which will in turn necessitate innovative methods of increasing water use efficiency and storage.
Structural water storage development (typically in the form of large dams) is becoming less socially acceptable. Water conservation, precision agricultural irrigation, and increased groundwater storage are ecologically and socially more acceptable solutions. Extreme events of the past few years in the Great Plains (e.g., floods in the Mississippi) might require re-evaluation of current structures. Although some large federally-funded infrastructure projects may have been designed to provide excess capacity as a reserve against climate change, smaller locally-funded projects do not have such excess capacity. Hence climate change might render such systems unable to perform these functions, leading to increased stress on local resources.
Changes of precipitation timing, regional distribution, intensity or form (rain, snow, hail, etc.), coupled with increased evapotranspiration rates will affect biological and agricultural resources in the Great Plains. A changing climate may increase problems of salinity and other pollutants in surface and groundwater. Such problems may be exacerbated by the intensified hydrologic cycle resulting from climate warming. Regulation of streams and rivers has already resulted in loss of the natural hydrological regime and a reduction of riparian habitat. In-stream flow requirements for restoring and maintaining biological diversity will compete with consumptive uses.
Water Demand
The scientific basis for determining needs of aquatic ecosystems under current and climate change scenarios should be further refined. Aquatic ecosystems in the Great Plains already face numerous stresses related to competing demands of agriculture and urban uses, not to mention water quality issues such as nitrogen runoff. Climate changes will place aquatic ecosystems under additional pressure. Temperature and precipitation changes will have a wide range of effects on the already vulnerable ecosystems. These effects range from dry wetlands and stream beds to major in-stream flow variability and increased demands on water supplies from agricultural and urban/residential users. Warmer air temperatures will affect water temperatures, increasing the ability of exotic/non-native species of pests, fish, and plants to migrate into Great Plains aquatic ecosystems and to disrupt these already stressed systems.
Considerable water is drawn from riparian aquifers that are recharged quickly through snowmelt and appropriate riverine management. More problematic are the regional groundwater aquifers which are not readily rechargeable under the present climate regime. The largest and best known among these is the Ogallala aquifer. Draw-down from the Ogallala Aquifer should be matched to the recharge from precipitation, in order to avoid depletion of the water resource. Changes in precipitation and evapotranspiration demand may lead to changes in recharge and draw-down, respectively. Use of surface water for irrigation is another water management issue. Consumptive water use by agriculture involves both flood irrigation from surface waters, particularly in the western portion of this region, and sprinkler irrigation derived from both surface waters and groundwater. More recently, there has been a trend toward precision irrigation and fertilizer application at critical times of the year. Management of both surface water and groundwater is a major political and management concern for this region - a concern that will be magnified by any decrease in available water concomitant with climate change. More efficient application methods (water pulsing, etc.) could decrease water consumption. Water availability in dryland systems and irrigated systems can both be improved by residue management and tillage practices. Ideally, the water demands of aquatic habitats and of the agricultural sectors (ranching and cropping) need to be negotiated in a non-confrontational manner.
Water Quality
Equally as important as water quantity in the Great Plains is the need to have water of sufficient quality for its intended use. The quantity of water available for particular uses depends on political, social and economic factors of allocation and control. Water quality is compromised by salinity and by runoff of fertilizers and wastes. Pressures for higher quality water stress regulatory and decision mechanisms. These pressures will be intensified if climate change reduces water availability.
Salinity management is an important issue in certain areas of the Great Plains. Rivers become more saline due to evapotranspiration, runoff and percolation through high saline soils. High salinity affects crop production and degrades fish and wildlife habitat. Many small towns in the Great Plains struggle to meet current drinking water standards. Non-point source pollution can include contaminants from fertilizers, herbicides, pesticides, livestock wastes, salts, and sediments that reduce the quality of both surface water and groundwater, the primary drinking water supplies. Changes in climate may also affect the numbers and types of pests. Pest control operations have the potential to affect water quality as water drains through crop fields, picking up pesticides. Currently, water quality and quantity changes have severely impacted fish and wildlife habitat in the Great Plains. Deterioration in water quality could have other adverse impacts on the ecosystem as well. Further research is needed to help determine the effects of climate change on water quality and ways to best mitigate water quality problems.
Wetlands
Wetlands provide critical hydrological, biological and biogeochemical functions, which have corresponding benefits valued by society. They provide flood control and water storage, assist in pollution filtering and waste processing, provide critical habitat and breeding grounds for birds and other species, and assist in the global cycling of carbon and nitrogen. Any wetland loss or degradation that interferes with these functions would have corresponding effects on the wetland benefits valued by society. In the Great Plains, prairie potholes have traditionally provided critical water storage and waterfowl habitat; it is estimated that prairie wetlands supply habitat for more than half the annual waterfowl population produced in North America. The central section of the Platte River has provided both food and protection for waterfowl and shore-birds during spring and fall migrations.
Wetlands are already under considerable stress throughout the world due to human activities such as draining for agriculture and urban expansion. Globally about half of all wetlands have been lost since around 1940. In the U.S., excluding Alaska, about 40-60% of wetlands have been lost, with percentages in some states (such as Ohio) as high as 90% (Baron, 1997). Wetlands in the Great Plains have undergone similar losses; in central Nebraska near the Platte River, most wetlands have been lost and those that remain are federal and private wetland projects (Tebbel 1997).
Wetlands will be affected by any changes in temperature, precipitation, and evapotranspiration, which alter the water supply to the wetlands through changes in runoff, streamflows, and groundwater recharge. Both the seasonal patterns and intensity of precipitation events are important. In the northern prairies, it is predicted that as evapotranspiration increases and snowmelt runoff decreases, a dramatic loss of meadow and shallow marsh lands would result (Baron, 1997). Wetlands in the central flyway in Nebraska would be adversely affected by any drop in river water levels during migration periods (Tebbel 1997). However, wetlands could be enhanced if increased precipitation exceeds evapotranspiration so as to provide consistently increased streamflow and groundwater supply.
Prairie pothole ecosystems are considered particularly vulnerable to climate change due to their inability to adapt through migration or other processes; this has been further exacerbated by human development in surrounding areas. Riverine ecosystems tend to have a higher potential to adapt through natural or assisted migration due to the high degree of spatial and temporal variability of their natural environment.
The focus for this group was on issues related to biological resources, such as changes in plant and animal communities, including the introduction of invasive weeds or pests, and the development of specialized crops and livestock breeds to meet climate changes. The group addressed issues related to native biota and processes, cultivation agriculture and livestock, and recreation.
Native Biota and Processes
This category includes population-, community- and ecosystem-level considerations of native biota that persist in small preserves and interstices of the eastern, intensively cultivated portion of this geographic domain, and expand into the dominant components of the rangelands in the western part of the domain. The entities of focus here--populations, communities and ecosystems of mainly native biota--have a different character from cultivated agricultural systems in particular, in that they are often complex in their composition, and are generally self-maintaining. They survive from one year to the next on the adaptive value of the traits with which they have evolved. They are less likely to benefit from ameliorative actions by humankind, are more vulnerable to land use change and climate change, and have a lower potential for adaptation to climate change than do agricultural systems. Particularly because of landscape fragmentation, native species will have difficulty dispersing or migrating to new locations of appropriate physical environments as opposed to deliberate planting and transport of agriculturally important species.
Changes in climate due to human-caused increases in CO2, methane and/or N2O have a high probability of augmenting the invasion of non-indigenous plants and animals and increasing the vulnerability of native flora and fauna to disease. It is expected that many native species, although not all native species, will be unable to adapt fast enough to new climate regimes and thus will be stressed, lowering their competitive edge and resistance to infections. Scenarios of increased average temperatures and precipitation may allow problem invasive plants now found further south to migrate into the central Great Plains (e.g. kudzu, Johnson grass). A warming and drying trend may reduce vegetative cover and provide open niches for invasion of species. Changes in water regimes may favor the invasion and increase of exotic mussels and fish at the expense of the native aquatic biota. Potential impacts include shifts in the relative abundance and distribution of native species, decrease in forage quality of rangeland, significant changes in species richness and assemblages, and extirpation of native species.
It would be prudent to take the steps now to better understand the process of invasion and the effects of invasive plants and animals. Rationally-based information is needed on the distribution and abundance of non- indigenous species. Analysis should be conducted to determine which pose a serious threat to managed resources (usually a small percent), and those which have a high potential to spread rapidly and cause impacts on native and managed ecosystems (based upon life history characteristics and history in other areas with similar climates).
There are already imbalances in predator-prey relations due either to the loss of the top predator (e.g., by loss of habitat or loss of prey as in the cases of black-footed ferrets and prairie dogs, or by deliberate extermination, as with wolves, etc.), or the rapid response of the prey populations to climatic factors (e.g., temperature and precipitation). Growing difficulties managing Plains waterfowl in the face of red fox predation is thought to be associated with coyote management. Climate change could accelerate these changes either directly (e.g., through temperature response of insect/prey populations) or indirectly (e.g., through habitat fragmentation and underlying changes in the food web).
Insect populations tend to be tightly coupled with climatic variability (i.e. temperature and precipitation) because of the potential rapid response of the population dynamics. Predator population dynamics are generally dampened and slower than prey dynamics. There are many examples of this phenomenon among insect populations. One such example is that grasshopper populations boom under dry conditions; increasingly dry conditions are a part of tentative climate change scenarios for the Central Plains.
Terrestrial habitat is largely defined by vegetation. Species composition, physiognomy or spatial distribution of vegetation types vary with environmental conditions and disturbance events. Typically, particular environments also feature one or more recurring disturbance type with a characteristic frequency. In presettlement time, vegetation (ecosystem) types occurred as large tracts, extensive continua, or mosaics. In some cases, similar habitats were connected by corridors of analogous environmental conditions such as rivers and ridgetops. For some species, these corridors were critical for maintaining metapopulations over large areas.
The original extent and spatial pattern of habitat was disrupted in the Great Plains more or less in proportion to the conversion of land to agricultural or urban use. Thus, original types of habitat are widely dispersed or absent in the agriculturally rich, eastern portions of the Great Plains, more frequent, if disconnected, in the central portion, and more continuous and in many ways similar to their former condition in the western margin of this geographic area. This regional-scale, quasi-gradient represents the template for the persistence of native species. The existence of some species may be dependent on sufficient appropriate habitat, sufficient core areas, or sufficient connectability between patches of appropriate habitat. For such species, appropriate habitat may entail very special edaphic or disturbance properties as well as climatic envelopes.
Maintenance of native biota is a difficult problem under circumstances prevailing in the margin of the region, where native habitat is more or less continuous. Maintaining enough habitat with sufficient connectability is nearly impossible in the intensively agricultural parts of the region. If climate change is added to a highly fragmented and altered landscape, the challenge of maintaining relatively common species, much less rare and endangered species, becomes highly problematic. Changes in the amount, timing, and variability of temperature and precipitation can all influence such species through a number of unpredictable mechanisms ranging from straightforward ecophysiological requirements, to pollination, predator-prey, and esoteric pest/parasite relations.
While maintenance of the original biota may be extremely difficult in the eastern portion of this geographic area, the problem becomes perhaps easier where native rangelands still prevail. Vegetative physiognomy, species composition, and other ecosystem properties may change in unpredictable ways, but there is a higher probability that native species may find themselves in acceptable habitat where dispersal is not inhibited by fragmentation.
Biodiversity encompasses the full array of native plants, animals, natural communities, and ecosystems that occur within the Great Plains. While the plains do not contain high numbers of species, there is a significant number of species that are rare, threatened, endemic, and/or declining. For example, there is much concern over the decline of endemic grassland birds, such as the mountain plover. Adequate habitat for shorebirds and neotropical migratory birds is another major concern. Biological inventories have been limited, and thus we lack a good understanding of the current biotic inventory status of biodiversity. Additionally, there is a lack of baseline reference information on some areas, particularly those that support large intact (naturally functioning) ecosystems, to preserve and maintain native species and communities. Biodiversity has become a societal value in itself, but ecosystem preservation is also important for hunting, fishing, recreation, and tourism.
Climate change will have variable impacts on biodiversity. With temperature change, not only will species need to migrate, but a number of species will likely go extinct, both locally and regionally. Changing land uses are likely to impact habitats of native plant and animal species. Natural migratory routes will likely be altered and/or interrupted by the changing climate.
Cultivated Agricultural Systems and Livestock
This category includes agroecosystems intensively managed by farm operators. These systems typically involve tillage, planting of prescribed crops (often monocultural), fertilization, and sometimes herbicide treatment and irrigation. These are relatively simple but highly productive systems, particularly in terms of commodities useful to humans. Because they are so intensively managed by humans, they can benefit from management strategies and decisions of farm managers. In that sense, they are relatively adaptable to climate change.
Demographic changes are increasingly causing destruction of habitats, which leads to reduction in biological diversity. Most of the world is experiencing loss of species diversity and loss of heterogeneity within species at alarming rates. The US has one of the lowest extinction rates in the world. While the US, and the Great Plains in particular, must be concerned with the loss of heterogeneity of their indigenous species, the well-being of US agriculture should also be concerned with the even more rapid loss of biological diversity in other countries.
The highest concentrations of genetic diversity of a species occur near the centers of origin of that species. With a few exceptions (e.g., sunflower, cranberry) most agronomic species in the US originate in other parts of the world. The main crops for the Great Plains, corn, soybeans, and wheat, have centers of diversity in Latin America, Manchuria, and Mid-East Asia, respectively. Thus, the raw materials for breeding of our cropping systems do not belong to us and are disappearing. The loss of these foreign populations will make American agriculture extremely vulnerable to climate change because it puts at risk the raw materials we would use to breed crops to adapt to the local biotic and abiotic stresses that result from changes in climate.
The same dynamic applies to livestock also. As with the genetic engineering of new and more resistant crop varieties, geneticists and breeders of livestock will hopefully be able to develop new lines of more robust livestock which, for example, will better tolerate extreme heat waves combined with high humidity. Additionally, breeding programs should select for improved resistance to pests, disease, and pathogens. An additional goal would be to breed for reduced methane production or to improve forage quality which could in turn reduce methane production.
Recreation
The rural communities of the region highly value their access to public lands for hunting, fishing and general recreation. In the case of fishing and hunting, land and water resources are often intensively managed by state or federal agencies to provide the public with prey species of choice. The ability of these agencies to add to or change these resources is extremely limited by their dependence on the availability of tax money.
If climate change negatively impacts the management situation of one of these resources, some recreation opportunities could decrease or disappear altogether. For example, spring rainfalls of increased frequency and intensity could severely impact the nesting success of ground nesting upland birds in a public hunting area. Likewise, game fish spawning success is very susceptible to increases in water temperature. Climate change effects such as these examples could eliminate public use opportunities.
Wetland and riparian systems are critical aspects of the lands used by hunters, anglers, and non-consumptive recreators (birdwatchers, etc.). The impacts to these habitats are covered elsewhere in this document but their importance to public land users is worth noting here. The hunting and angling communities represent important political constituencies within this issue. These communities invest considerable sums towards these activities and will not ignore negative changes due to global warming. So they need to be involved as soon as possible. One way to promote their involvement is to develop models that help determine how habitat and quality changes will impact wildlife and fisheries. Such studies would provide communications and educational tools to involve these constituencies. Although it's important to get them involved, the information should be translated into "lay person's" terms. If they clearly understand, they are likely to be supportive.
Recreational activities play a large role in the lifestyle of many who live in the Great Plains. Climate variability will add a great deal of uncertainty for those who plan activities in the Great Plains area. The economic base might also be eroded through decreased tourism and recreational dollar revenues coming into the Great Plains states.
This group addressed issues related to soil resources, such as soil erosion, fertility, and salinization, as well as land management issues. Many issues related to solving soil problems involve the socio-economic sector in order to effectively develop strategies that will lead to sustainable practices. The issues discussed in this section include soil quality/degradation, land management, and disturbance.
Stresses on Soil Resources
The current stresses on soil and land resources for agriculture in the Central Great Plains are to a large degree associated with the conventional dryland cropping system of wheat fallow practiced in the region. Briefly, this practice consists of fall (Sept) planting of winter wheat which is harvested in early summer (June-July) the following year. Fields are then bare-fallowed for the remainder of the year and through the following year until the new fall planting. In the bare fallow phase the soil is periodically cultivated to suppress weeds. Thus, over the two year period the soil is without vegetation cover and is periodically disturbed over a 14 month period. This system was developed to cope with the low and highly variable precipitation in the region, in that the fallow period allows soil water to be stored for use in the subsequent crop. In addition, nutrients released during the fallow period are often sufficient to meet crop requirements, and historically no fertilization or only low rates of fertilization have been used. This system has conferred production stability, in the short-term, to farmers in the region but has also led to a variety of problems which call into question its long-term sustainability. Under wheat-fallow, soil organic matter typically declines by 50% or more due to the low rates of residue return and the favorable conditions for decomposition, with intense soil disturbance, during the fallow phase. The 'mining' of nutrients and organic matter is detrimental to soil structure and fertility. Crop water use efficiency is low and with periods of excess water, nutrient leaching below the root zone and formation of saline seeps on hillslopes can occur. Clean fallow practices leave the soil susceptible to wind and water erosion.
These ecological stresses interact with a variety of other stress factors relating to economic, policy and social conditions for agricultural communities in the Great Plains. While solutions for soil degradation problems resulting from conventional farming practices are largely known, and are to some degree being implemented at present (see section on Coping Strategies), many of the economic, policy and social stress factors interact, often in subtle ways, to inhibit opportunities for the broad implementation of more sustainable practices. Soil degradation has been and remains a problem particularly with summer-fallow management practices, leading to soil organic matter depletion, degraded soil structure, increased erosion risk, potential for nutrient leaching and saline seeps together with reduced water use efficiency. Warmer temperatures would add an additional stress on organic matter maintenance due to higher potential decomposition rates. More intense storms could lead to increased erosion. Therefore many considerations of interest to this group regarding barriers to improved management of the soil resource can be found in the Social Section of this report.
Land Management
Mixed farming operations incorporating livestock and rangeland with crop production offers advantages in diversification and efficient use of resources. However, economic and particularly social factors (see below) are significant barriers. Low rates of return make it difficult to invest in rangeland improvement. Invasive weeds are a problem due to the greater fragility of semi-arid rangelands and again high costs relative to economic return for control measures. Producers in the workgroup perceived a decline in government support for research focusing on mixed livestock-crop production systems.
Management of rangelands is an important land use in the central portion of the Great Plains. Rangeland management is the dominant land use throughout the area in the westernmost portion, except where flood and spray irrigation dominates along riparian systems. Some rangelands are composed of domestic or native cultivars planted as highly managed pastures, but many are composed of native grass-dominated ecosystems derived in an unknown form from presettlement time. These more extensively managed rangelands of the western margin of the geographic domain overlap with the native biota part of the Biology section.
The rangelands of the western portion of the Great Plains have undergone extensive changes in use from presettlement grazing by native bison and pronghorn antelope and small mammals, to extremely heavy use by cattle and sheep in the late nineteenth century, to the more moderate grazing levels practiced in the latter part of this century. While it is widely accepted that rangelands are in better condition now than they were in the 1880s, we do not have good benchmarks for the state of rangelands before the introduction of exotic ungulates. The issue of "rangeland condition" and "good range management" is an undying one of intense resource use and political debate. Recently, the traditional measure of rangeland condition within a successional paradigm has been discarded, but as of yet, there has been no replacement in terms of structural or functional properties. Setting criteria for, and judging rangeland condition is a research issue today.
Range quality and ecologically sound range management are best evaluated in two zones: the vast areas of upland range and the much smaller but crucial riparian areas. While most would agree that the upland range is generally in good condition by most criteria, the situation for riparian zones is quite different and quite variable. In some instances, improper use of the riparian zone through overgrazing or grazing in the wrong season has led to loss of riparian vegetation and disruption of the geomorphological balance of the stream system itself. Streams that formerly had broad floodplains are now deeply entrenched and surrounded by low grade vegetation of the high, surrounding benches. Another problem with riparian zone management is the withdrawal or impoundment of springtime and storm flows so that seasonal floods are rare or non-existent. Without occasional floods of the appropriate frequency and magnitude, some riparian species such as cottonwood are not reproducing and entire gallery forests are being lost to attrition of aging trees. With the loss of gallery forests are lost both non-game and game species habitat.
Climate change, involving either long-term secular trends, or changes in variability around current mean conditions, is likely to change the character of rangelands. Native rangelands usually involve a number of plant species sorted in various ways along environmental gradients or reflecting historical accidents of disturbance. Climate change in terms of temperature ranges, precipitation amounts or timing, are likely to alter the composition of the rangelands in either a more xeric or more mesic direction. Climate change may also alter the occurrence or abundance of woody, graminoid or forb species. Such changes will redefine baselines for range conditions on particular sites and along environmental gradients. In the processes of native species losses and replacements, disturbances may enhance establishment opportunities for alien plant species. Changes in soil carbon, nitrogen dynamics and erosional processes are likely to be complex as are plant-herbivore relations with mammals and insects. These disruptions will extend to riparian zones as well as to the upland matrix and in some circumstances may be even more serious than where regular water supply and particular flood regimes are mandatory for ecosystem maintenance.
Disturbance Regimes
Disturbance patterns play a major role in structuring biotic communities, creating a range of environments that favor different certain species over time. Mortality or removal of plant material by fire, drought, freezes or erosion creates environments that may favor some species of plants or animals over others. Since many disturbances are linked to climate, if climate patterns change, then the types and frequencies of disturbances may also change. For example, changing patterns of temperature and precipitation could affect wildfires directly by affecting the dryness of the vegetation and indirectly by favoring more or less combustible vegetation. Climate changes could alter streamflow regimes, causing low water or flood impacts on aquatic and riparian communities. In evaluating the effects of climate change on natural and managed ecosystems, the possibility that effects may occur through changes in disturbance regime, rather than by direct physiological effects on organisms, must be investigated.
Land is closely tied with water and with issues of water allocation and control. The salient trend is increasing development of land, and stresses develop when the developments and growing population pressures collide with multiple competing uses: farming, grazing, timber, watershed protection, mining, and recreation. Fire and pests also "compete" with these uses.
Climate change will potentially change the dynamics of balance among these competitors, increasing social tensions. For example, decreasing precipitation and/or increasing temperature could make watershed protection more important and fire more likely.
Agricultural burning and wildfire in the forest areas of the Great Plains were two concerns raised by the group, but not further discussed. The concerns raised include: a change in the frequency of fire, especially wildfire. If precipitation increases, fuel will increase on the forest floor. Under a drought scenario, forests will be more susceptible to fire. The impact of agricultural burning may further impact natural and urban areas under climate variability.
Extensive strip mining for soft coal occurs in thick beds in the Powder River Basin of northeastern Wyoming. All of the minable coal seams lie in an area which happens to be a coarse mosaic of sagebrush-dominated or grass-dominated rangeland. The vast majority of this rangeland is composed of native species in generally good condition, and is managed for cattle, and to a limited extent, bison. Upland wildlife is abundant, particularly pronghorn antelope, small mammals, raptors and various plains carnivores. After the coal is mined, the mined land is returned to original contour and replanted into nurse grasses, native grasses, and shrubs. Considerable effort is put into careful reclamation as the mining companies are required to place a bond in reserve guaranteeing reclamation following coal extraction. A goal of reclamation is to return the area to productive rangeland much like that found originally, and to return the overall area to its original landscape pattern. This entails topsoil banking and redistribution, planting, fertilization and irrigation. Changes in climate may require a change in the target rangeland ecosystem type. Furthermore, it may produce new problems in preventing erosion and guaranteeing establishment of desired plant species.
Land use practices considerably change the distribution and timing of water vapor returning to the atmosphere. Some land use practices that may alter climate include the change from short grass prairies to deep rooted dryland and irrigated crops. These, as well as potential changes from greenhouse effects, may affect changes in Great Plains temperatures and precipitation.