Ecological Applications, 21(3) Supplement, 2011, pp. S49–S64 Ó 2011 by the Ecological Society of America

Agricultural conservation practices increase ecosystem services in the Glaciated Interior

1,3 2 SIOBHAN FENNESSY AND CHRISTOPHER CRAFT 1Department of Biology, Kenyon College, Gambier, Ohio 43022 USA 2School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana 47405 USA

Abstract. The Glaciated Interior Plains historically supported a broad variety of wetland types, but wetland losses, primarily due to agricultural drainage, range from 50% to 90% of presettlement area. Wholesale land use change has created one of the most productive agricultural on earth, but wetland conversion has also led to the loss of the ecosystem services they provide, particularly water quality improvement, flood de-synchronization, carbon sequestration, and support of wetland-dependent species (biodiversity). Nearly three-quarters of the Glaciated Interior Plains fall within the , where the combination of extensive tile drainage and fertilizer use has produced watersheds that contribute some of the highest nitrogen yields per acre to the Mississippi River. Wetland conservation practices implemented under Farm Bill conservation programs have established or involved management of nearly 110 000 ha of , riparian zones, and associated ecosystem services over the period 2000–2007. We estimated the cumulative ability of these conservation practices to retain sediment, nitrogen, and phosphorus in Upper Mississippi River Basin watersheds. Estimated retention amounts to 1.0%,1.5%,and0.8% of the total N, sediment, and P, respectively, reaching the each year. If nutrient reduction is estimated based on the quantity of nutrients exported from the Glaciated Interior Plains only, the numbers increase to 6.8% of N, 4.9% of P, and 11.5% of sediment generated in the region annually. On a watershed basis, the correlation between the area of wetland conservation practices implemented and per-hectare nutrient yield was 0.81, suggesting that, for water quality improvement, conservation practices are successfully targeting watersheds that are among the most degraded. The provision of other ecosystem services such as C sequestration and biodiversity is less well studied. At best, implementation of wetland and riparian conservation practices in agricultural landscapes results in improved environmental quality and human health, and strengthens the rationale for expanding conservation practices and programs on agricultural lands. Key words: carbon sequestration; flood abatement; Glaciated Interior Plains, USA; nitrogen; U.S. Midwest; water quality improvement.

INTRODUCTION supply, fish and fiber production, recreational opportu- nities, and tourism) that contribute substantially to The Glaciated Interior Plains (GIP) covers most of a human well-being (Millenium Ecosystem Assessment seven-state area stretching from Ohio to Minnesota, 2005). Within the GIP, wetland ecosystem services such USA, encompassing a broad variety of landscapes and as flood abatement, water quality improvement, and the associated wetlands. Sometimes referred to as the ‘‘corn support of biodiversity have declined dramatically due to belt,’’ this area is one of the most productive agricultural extensive wetland drainage (Hey 2002, Zedler 2003b). One regions on earth, accounting for .50% of the nation’s consequence of wetland loss, combined with regionally corn production (Power et al. 1998), as well as extensive intense agricultural inputs (fertilizer, pesticides), is the production of , , and other grains. The chronic degradation of water quality, particularly in the wholesale land conversion that occurred to make way for upper Mississippi River Basin, which ultimately contrib- resulted in a loss of native ecosystems, utes to hypoxia in the Gulf of Mexico. This paper including wetlands, reducing their ability to provide describes what is known about the types and status of critical ecosystem services. Globally, wetlands deliver a wetlands in the GIP and how conservation practices wide range of services (e.g., water purification, climate implemented through Farm Bill conservation programs regulation, flood regulation, coastal protection, water contribute to the restoration of wetland ecosystem services, particularly water quality improvement.

Manuscript received 16 February 2009; revised 17 November DIVERSITY OF WETLANDS IN THE GLACIATED 2009; accepted 23 November 2009; final version received 5 INTERIOR PLAINS January 2010. Corresponding Editor: J. S. Baron. For reprints of this Special Issue, see footnote 1, p. S1. The GIP of the Midwest (Fig. 1) contain 3 E-mail: [email protected] a variety of wetland types that exhibit extensive spatial S49 S50 SIOBHAN FENNESSY AND CHRISTOPHER CRAFT Ecological Applications Special Issue variability, differing from east to west as precipitation shorter hydroperiods than in the region. Soils decreases and from north to south with increasing tend to be saturated, and not inundated (Prince 1997). temperatures. The climate of the region is characterized In the eastern part of the region, wet meadows are found as temperate continental with subhumid to humid in association with oak savannas of the mesic prairie summers and cold winters (Trewartha 1981). Mean landscape (Nuzzo 1986). These wetlands support a rich annual temperatures range from 11.18C in the east diversity of plants (Table 1), and threatened (Columbus, Ohio) to 9.68C in the west (Des Moines, birds such as Greater Prairie-chicken, Tympanucus Iowa), with associated rainfall ranging from 96.2 cm to cupido, that use these habitats for roosting (Toepfer 77.7 cm (Amon et al. 2002). Much of the region was and Eng 1988). shaped in the most recent, Wisconsin glaciation, which In the north (Wisconsin, Minnesota, northern produced the current distribution and type of wetlands, Michigan), peat-accumulating wetlands ( and ) including depressional marshes, shrub and forested bogs, are common landscape features. Bogs receive essentially fens, forested wetlands, and wet meadows. Wetlands of all of their water and nutrients from precipitation, the Midwest can be distinguished on the basis of the making their peat acidic (pH , 4), low in available dominant water source, consisting of those that receive nutrients, with an enormous store of carbon (Table 1; water mostly from surface flooding (floodplain and Grigal 1991, Crum 1995, Bridgham et al. 2001). Other riparian forests), precipitation (depressional wetlands, wetlands in the northwestern portion of the region vernal pools, bogs), groundwater (fens, seeps), and a include glacially formed lakes with extensive littoral combination of sources (e.g., wet meadows) (Fig. 2). In zones dominated by vegetation (Tiner 2003). the east (Ohio, Michigan, Indiana), forested wetlands (depressional, seep, and riparian), marshes, and fens are WETLAND LOSSES,LANDSCAPE CHANGE, predominant. Forested riparian wetlands are common AND ECOSYSTEM SERVICES along floodplains (Brown and Peterson 1983, Rust and The conversion of wetlands to crop and pasture lands Mitsch 1984, Polit and Brown 1996, Baker and Wiley over the past 250 years has transformed the landscape of 2004). These wetlands provide important ecosystem the GIP. Humans cleared forests, broke sod, and services, including water quality maintenance, habitat, drained wetlands to clear land and facilitate farming. and flood de-synchronization (Table 1). An unintended consequence of this land conversion was Depressional wetlands exist on broad, upland flats in degraded water quality, flood damage, diminished topographic low spots, and to a lesser extent, on biodiversity, and radically altered regional hydrology floodplains and are dominated by either forested or (Prince 1997, Hey et al. 2005). Because hydrology herbaceous emergent vegetation (Galatowitsch et al. determines the location of wetlands and their structural 2000, Craft et al. 2007). Depressional wetlands lack and functional properties, agricultural expansion has strong surface water connections to other aquatic caused not only an enormous loss of wetland acreage, ecosystems and, although they are sinks for pollutants but has also compromised the ability of existing in the local landscape, their role in regional water quality wetlands to provide their characteristic ecosystem maintenance is less well understood (Table 1). However, services (Zedler 2003b). they are important habitat for wetland-dependent avian, Agricultural land use dominates the region, ranging fish, and amphibian species, and as watering holes for from 93% agricultural land use in the state of Iowa to animals. Vernal pools represent a special type of 30% in Michigan. Much of this land is drained using depressional wetland. They are typically smaller in size drain tile to move water (and associated chemicals) and forested, with a shorter hydroperiod than depres- quickly from the field to adjacent ditches and streams. sional wetlands such as marshes (Zedler 2003a). Because The extent of tile drainage underlying croplands ranges of the short hydroperiod, these wetlands lack predators from 50% in Ohio and Indiana (;3 3 106 ha in each such as fish, making them critical sites for amphibian state) to 10% (0.9 3 106 ha) in Wisconsin (Mitsch et al. reproduction (Table 1; Gibbons 2003). 1999). Over 40% of the N fertilizer used in the United Fens and seeps occur in areas where mineral-rich States is applied to agricultural lands in the GIP. Of this, groundwater discharges. They are typically low in 35% is estimated to run off into receiving waters nutrients, particularly P, and high in carbonates with (Howarth et al. 2002, Zedler 2003b). high plant species diversity (Bridgham et al. 1996, Amon As part of these land use changes, large areas of et al. 2002). Fens and seeps often have strong connections wetlands once common throughout the Midwestern to regional groundwater flows that deliver carbonates states have been lost, and with them the landscape’s – (CaCO3), as well as nutrients (NO3 ) leached from ability to regulate water movement and biogeochemical agricultural lands (Amon et al. 2002, Craft et al. 2007). cycles. Wetland conversion to make way for agriculture Wetlands of the central portion of the Midwest came early; for example, the four states that make up the (, Iowa, southern Wisconsin), where annual bulk of the GIP lost between 80% and 90% of their precipitation is less than in the east, consist of forested original wetland acreage between 1780 and 1980 (Dahl floodplains and stream corridors, freshwater marshes, 1990), including Ohio (90%), Indiana (87%), Illinois and wet meadows and prairies. Wet meadows possess (85%), and Iowa (89%). In addition, two enormous April 2011 WETLAND SERVICES IN THE GLACIATED PLAINS S51

FIG. 1. Map of the USDA Natural Resources Conservation Service (NRCS) assessment regions under the Conservation Effects Assessment Program (CEAP). Region 1, expanded in the inset, represents the Glaciated Interior Plains (GIP). wetland complexes, the Great Black in north- western Ohio and the Great Kankakee Marsh in northern Indiana and Illinois, each more than 1 000 000 acres (400 000 ha) in size, were systematically drained for agriculture and no longer exist today (Mitsch and Gosselink 2000). Losses in the northern- tier states are lower, with nearly half of the original wetland acreage lost (Michigan lost 50%, Wisconsin 46%, and Minnesota 42%; Dahl 1990). The push for wetland drainage slowed dramatically in Wisconsin and Michigan in the early 1900s, when many peat soils were found to be acidic and deficient in essential plant nutrients (Prince 1997). Collectively, the seven states that make up the GIP have had ;18.6 million ha of farmland drained for agriculture (Mitsch et al. 1999).

Water quality impacts

The loss of wetlands from a landscape removes their FIG. 2. Relationship between water source and wetland capacity to act as sinks and transformers of sediments, type. The figure is modified from Brinson (1993). S52 SIOBHAN FENNESSY AND CHRISTOPHER CRAFT Ecological Applications Special Issue

TABLE 1. Wetland types of the Midwest (USA) and their relative contribution for delivering ecosystem services related to water quality maintenance, habitat, hydrology, and carbon sequestration.

Water quality Carbon Wetland type maintenance Habitat Hydrology sequestraiton Riparian forest high high low–mediumà low Floodplain forest high high highà low Depression low high§ medium# low low high§ low low low–medium medium} low–medium low–medium low–medium high} low medium Seep low medium low low low high} medium# high High productivity and connectivity. à Flood de-synchronization. § Breeding grounds for herpetofauna. } High plant diversity. # Groundwater recharge. nutrients, and other chemicals that they receive. This drained and floodplains developed (Hey and Philippi service can vary both temporally and spatially, but 1995, Zedler and Kercher 2005). The Mississippi River wetlands have consistently been shown to improve the flood of 1993 alone cost an estimated $12–$16 billon. water quality of nonpoint source runoff, and wetland losses have contributed to reductions in water quality in Support of diversity the region. The combination of extensive drainage and One consequence of widespread wetland losses is the intensive row crop fertilization in the GIP has produced decline of wetland-dependent species such as amphibi- watersheds that contribute some of the highest nitrogen ans, invertebrates, and waterfowl, as well as species that yields per acre to the Mississippi River (nearly three- are primarily terrestrial but use wetlands for refugia and quarters of the GIP region is located in the Mississippi subsidy (Hansson et al. 2005). In the case of amphibians, River watershed; Goolsby et al. 1999). The environmental habitat loss and fragmentation are recognized as major consequences of this are particularly well documented, causes of diversity declines (Hecnar and M’Closkey where high N export has led to downstream water quality 1996). Amphibians are particularly at risk due to their issues, most notably the hypoxic zone (or the ‘‘dead relatively poor dispersal abilities (Findlay and Houlahan zone’’) in the Gulf of Mexico (Rabalais et al. 2002). 1997, Lehtinen et al. 1999). Two particular species of Agricultural sources are responsible for an estimated 58% anurans that occur in the GIP and are reportedly in of nitrogen export in the Mississippi River Basin due decline are the northern leopard frog (Rana pipens) and primarily to fertilizer use and the planting of legume the cricket frog (Acris crepitans blanchardi) (Kolozsvary crops (soybeans). The Illinois River watershed alone, and Swihart 1999). which constitutes only 2% of the area of the Mississippi Reptiles are relatively unstudied, but data indicate River watershed, contributes ;114 000 Mg of nitrate per that taxa such as freshwater turtles have declined as year (or 12% of the total nitrate load) to the Gulf of agriculture and road density have increased (Rizkalla Mexico (Hey 2002). Like much of the Glaciated Interior and Swihart 2006), with predictions that wetland- Plains, nearly 90% of the original wetland area in the Illinois River watershed has been drained. Over the past dependent herpetofauna face a greater risk of extinction 50 years, fertilizer use in the region has intensified, and N than other vertebrate species (White et al. 1997). loads from the upper Mississippi River Basin to the Gulf Wetland invertebrates provide an important connection of Mexico have increased nearly three-fold since 1950 between primary productivity and the abundance of (Rabalais et al. 2002). migratory and resident vertebrate populations, serving as important food supplies for a wide array of bird Flood abatement species such as bitterns, egrets, herons, shorebirds, Wetlands naturally trap and store water, and flood- waterfowl, and songbirds (Hershey et al. 1999). plains are particularly important in water storage and Despite this, there are few data on the status of flood conveyance. As floodplains and wetlands have been invertebrate communities in light of wetland losses. altered or lost, their ability to store floodwaters in the Bird diversity is known to decline with wetland area, so GIP has diminished. Nationally, the estimates of damage wetland loss has consequences for the persistence of due to flooding have risen steadily since 1900, increasing avian species in the region (Hershey et al. 1999). Thus, from an annual mean of US$1.4 billion over the 30-year the loss of wetlands in the GIP has contributed directly period 1903–1933 to $3.4 billion during 1963–1993 (Hey to declines in regional biodiversity (Findlay and and Philippi 1995). This occurred as wetlands were Houlahan 1997, Hershey et al. 1999). April 2011 WETLAND SERVICES IN THE GLACIATED PLAINS S53

Despite the extent of agricultural land use, the species wildlife habitat management (a system of practices that richness of remaining wetlands can be high. For establishes or restores wildlife habitat, and may be example, Mensing et al. (1998), in a study of 15 riparian implemented with wetland restoration, creation, or wetlands, documented 175 plant species and 151 animal enhancement practices), and riparian forest buffer species (including birds, fish, amphibians, and macro- establishment (establishment of a riparian forest buffer invertebrates), demonstrating the value of wetlands in along streams where former riparian wetlands existed or biodiversity support. where they currently exist but in a degraded state). These practices are collectively referred to as ‘‘wetland conser- Carbon sequestration vation practices.’’ Implementation of these practices is Hydrologic conditions that lead to the accumulation supported by financial and technical assistance as codified of soil carbon are a defining feature of wetlands in the conservation title of what has become known as the (Bridgham et al. 2007). Carbon storage capacity varies ‘‘Farm Bill’’ to achieve environmental or biological goals depending on wetland type, with peatlands (freshwater on agricultural and associated lands. In this case, the wetlands with surface soil organic deposits greater than Farm Bill refers to a series of legislative acts, including the 40 cm thick, commonly called bogs and fens) storing Food Security Act of 1985; the Food, Agriculture, considerably more C than wetlands with mineral soils Conservation and Trade Act of 1990; the Federal (those with less soil organic matter). Globally, peatlands Agricultural Improvement and Reform Act of 1996; the contain between 16% and 33% of the total soil carbon Farm Security and Rural Investment Act of 2002; and the pool (Bridgham et al. 2001). While the majority of Food, Conservation and Energy Act of 2008. peatlands occur north of 508 N, there are substantial Collectively, these conservation practices have added to areas of peatlands in the upper GIP (Gorham 1991, or enhanced more wetland acreage in the agricultural Bridgham et al. 2007). Bogs receive nearly all of their landscapes of the GIP than in any other region included water from precipitation (Fig. 2), the peat is acidic, in this study. The implementation of wetland conserva- nutrient poor, and only slightly decomposed (Bridgham tion practices supported by a variety of Farm Bill et al. 2001). Fens are typically phosphorus limited but, conservation programs (e.g., Wetlands Reserve Program because of groundwater inputs, they are not as acidic as [WRP], Conservation Reserve Enhancement Program bogs and contain more highly decomposed peat [CREP], Conservation Reserve Program [CRP], Wildlife (Bridgham et al. 2001). The slower rate of decomposi- Habitat Incentives Program [WHIP]) are expected to tion (i.e., carbon mineralization) in bogs compared to reestablish ecosystem services, providing regional benefits fens (Bridgham et al. 1998) leads to deeper peat and in terms of water quality, flood abatement, biodiversity organic C accumulation (Craft et al. 2008). support, and carbon storage. Regionally specific estimates of carbon storage in the In total, .1 million wetland conservation projects GIP are lacking, but wetland drainage has reduced were implemented in the GIP, accounting for 33.4% of carbon stores substantially, perhaps by as much as 15 all practices implemented nationally between 2000 and million Mg of carbon per year in 2006, and amounting to ;110 000 ha (1100 km2) of land. (Bridgham et al. 2006). The loss of C storage has In terms of area, the wetland practices implemented are diminished wetlands’ role as climate regulators. dominated by wetland restoration, followed by the establishment of wetland wildlife habitat, and riparian EFFECTS OF NRCS CONSERVATION PROGRAMS AND buffers (Fig. 3). Over 80% of wetland conservation PRACTICES ON WETLAND ECOSYSTEM SERVICES practices in the GIP were implemented between 2004 Of the ecosystem services wetlands provide, four are and 2006, demonstrating the potential for landscape particularly significant in the GIP: water quality change over a relatively short time period (Fig. 3). improvement, flood abatement, biodiversity support, At the regional scale, we examined the distribution of and carbon processing and storage. We focus here on conservation wetlands and riparian zones by mapping water quality improvement, and to a lesser extent on the top 100 subwatersheds in the GIP based on the total flood abatement, biodiversity support, and carbon area of wetland conservation practices established in storage. This follows, in large part, what we know each (Fig. 4). The largest concentration of wetland based on the available literature. conservation practices is located in the southwestern In order to restore wetland and riparian-zone acreage part of the GIP that largely coincides with the drainage to the landscape, a suite of conservation practices has basin of the Mississippi River. Subwatersheds that been developed by the USDA Natural Resources received the largest acreage of wetland conservation Conservation Service (NRCS) specifically to establish or include the Rock River in Illinois and the Wabash River manage wetlands on agricultural and associated lands. in southern Illinois and Indiana. These practices are designated as: wetland creation (establishing wetlands on non-hydric soils), enhancement Water quality maintenance (typically changing the hydroperiod of an existing Because of their high connectivity to uplands, riparian wetland using water control structures), restoration and floodplain forests are important regulators of the (establishment of wetland on hydric soils), wetland flow of materials across the landscape, reducing S54 SIOBHAN FENNESSY AND CHRISTOPHER CRAFT Ecological Applications Special Issue sediment and phosphorus (P) and nitrogen (N) loads to in the Gulf of Mexico (Turner and Rabalais 1991, streams and rivers (Risser 1993, Fennessy and Cronk Rabalais et al. 2002). Natural and restored wetlands, 1997). Riparian and floodplain forests can remove riparian areas, and constructed wetlands have the substantial amounts of sediment (Table 2); for example, potential to reduce nitrate loadings and help alleviate riparian wetlands trap up to 50 Mgha1yr1, substan- this problem. Whitmire and Hamilton (2005) reported tially more than floodplain forest’s 2–5 Mgha1yr1. that a variety of natural wetlands in Michigan, ranging Sediment accumulation is low (0.2–2 Mgha1yr1)in from groundwater fens to precipitation-driven bogs, groundwater and precipitation-driven wetlands such as have the potential to remove significant amounts of depressions, bogs, and fens. Phosphorus removal also is nitrate. In Illinois, grass and forested riparian buffers greater in riparian forests and floodplain wetlands reduced local nitrate loadings by up to 90% (Osborne (Table 2). And N accumulation in soils is greater in and Kovacic 1993), and forest vegetation, because its floodplains (30–300 kg Nha1yr1) than in bogs (80 kg roots penetrate deeper and deliver more carbon to Nha1yr1), fens–cedar (30–60 kg Nha1yr1), denitrifying bacteria, was more effective than grass for or depressions (30 kg Nha1yr1). Constructed wetlands intercepting nitrate as it is preferentially transported in in the region remove relatively large amounts of sediment subsurface flow (Fennessy and Cronk 1997). and nutrients, comparable to riparian and floodplain Tile drainage complicates the removal of N from wetlands (Table 2). agricultural runoff since wetlands typically have little Denitrification is the primary process by which nitrate opportunity to intercept N in this water (Crumpton et al. is transformed by wetlands, thereby removing a key 2006). Where wetlands can intercept tile drainage, N- waterborne pollutant (Table 3). Because of their removal efficiencies are high. In a study of the Iowa connectivity to lotic ecosystems, high C availability, CREP program, Crumpton et al. (2006) report that and inflows of nitrate, denitrification is greater in wetlands restored to intercept tile drainage removed – riparian and floodplain wetlands than in depressions, between 25% and 78% of NO3 amounting to 368–2310 bogs, or fens in the region (Table 3). Riparian wetlands kg Nha1yr1. In another study in Illinois, a constructed intercept nitrate in shallow groundwater (Gilliam 1994, wetland removed an average of 33% of the N in tile Hill 1996), whereas river flooding enhances denitrifica- drainage (Miller et al. 2002). However, there was no tion of surface water nitrate in floodplain wetlands significant removal of P or nine common herbicides (e.g., (Hernandez and Mitsch 2006). Although depressions, atrazine, alachlor) used in the Midwest. Phosphorus bogs, and fens are not as important for water quality removal by constructed wetlands receiving tile drainage improvement as riparian and floodplain wetlands, they typically is low, as little as 2% (Kovacic et al. 2000) are significant nutrient sinks at local scales (Craft and because much of the P (.50%) is transported bound to Casey 2000, Whigham and Jordan 2003). sediment in surface waters (Royer et al. 2006). Little is In the GIP, riparian buffers and constructed wetlands known about the relative effectiveness of different are increasingly employed as the best management conservation practices (e.g., vs. practices to filter sediment and nutrients and improve wetland restoration) in improving water quality, and water quality. From a landscape perspective, studies what the associated trade-offs might be between water suggest that nutrient export from stream catchments is quality improvement and other ecosystem services. correlated with the presence of wetlands and with the Constructed wetlands also have been used to remove extent and characteristics of the (e.g., instream pollutants. These wetlands typically receive buffer width, vegetation type). In Wisconsin, catchments higher loads of sediment and nutrients and, so, remove with more wetland area (7–10% vs. ,4%) had lower P greater quantities of pollutants than natural wetlands in yields during extreme precipitation events (Reed and the region (Table 2). Four wetlands were constructed in Carpenter 2002). Variability in P yield was negatively the floodplain of the Des Plaines River (Illinois) in the correlated with riparian characteristics of width, conti- late 1980s to filter sediment, nutrients, and agricultural nuity, and sinuosity, suggesting that preferential trans- chemicals from the river water (Kadlec and Hey 1994). port of nutrients to stream waters occurs in gaps in Over a three-year period, the wetlands removed riparian corridors, such as those created by roads (Reed between 40% and 95% of incoming nitrate-N, 38– and Carpenter 2002). The placement of buffers within 100% of the incoming sediment, 27–100% of the the landscape to intercept nutrients and other pollutants phosphorus, and ;50% of the herbicide atrazine also is important. In Iowa, researchers calculated that (Fennessy et al. 1994, Kadlec and Hey 1994, Phipps 56% of riparian cells (using a 30-m grid) surveyed would and Crumpton 1994). Removal rates were greater in the receive runoff from ,0.4 ha (Tomer et al. 2003), summer than winter, illustrating how removal efficien- suggesting that it is important to strategically place cies vary with season. Flow rates also regulated nutrient riparian buffers in areas that will maximize interception retention as the efficiency of P removal was greater of water, sediment, and nutrient flows. under low-flow (64–92% removal) than high-flow In the agricultural Midwest, nitrate leaching is a conditions (53–90% removal; Mitsch et al. 1995). On significant problem, enriching streams and rivers average, the constructed wetlands removed ;5–30 kg (Keeney and DeLuca 1993) and contributing to hypoxia Pha1yr1; comparable to highly loaded natural April 2011 WETLAND SERVICES IN THE GLACIATED PLAINS S55

FIG. 3. The area of wetland conservation practices implemented in the Glaciated Interior Plains between 2000 and 2006. wetlands. The percentage of nitrate removal was also stored an average of 43–47 Mg sedimentha1yr1, greater under low- than high-loading conditions in these 162–166 kg Nha1yr1, and 33–35 kg Pha1yr1 in soil wetlands (Phipps and Crumpton 1994). (Table 2). During the same period, the wetlands removed On the Olentangy River (Ohio), constructed wetlands an average of 410–470 kg Nha1yr1 of nitrate-N via also remove substantial quantities of sediments and denitrification, with only a small amount, ,1%, evolved as nutrients. Over a 10-year period (1994–2004), the wetlands N2O (Hernandez and Mitsch 2006).

FIG. 4. The top 100 watersheds in the Glaciated Interior Plains (by hectares and acres) of wetland conservation practices implemented through Farm Bill conservation programs. The conservation practices include Wetland Creation, Wetland Restoration, Wetland Enhancement, Riparian Forest Buffer, and Wetland Wildlife Habitat Management. S56 SIOBHAN FENNESSY AND CHRISTOPHER CRAFT Ecological Applications Special Issue

TABLE 2. Rates of sediment, P, N, and C accumulation in soils of Midwestern wetlands.

Wetland type Sediment P N Organic C and state (Mgha1yr1) (kgha1yr1) (kgha1yr1) (kgha1yr1) Source Riparian Wisconsin 5–78 82 524 Johnston et al. (1984) Missouri 50 Heimann and Roell (2000) Floodplain Illinois 34 Mitsch et al. (1979) Wisconsin 5 11 27 540 Johnston et al. (1984) Indiana 2.5 7–14 92–295 1200–3700 N and P data from Craft and Schubauer-Berigan (2006), C data from C. B. Craft (unpublished data) Wet meadow Michigan 10 Kadlec and Robbins (1984) Marsh Indiana depressional 1.8 30 610 C data from Craft et al. (2008); sediment, P, and N data from C. B. Craft (unpublished data) Michigan lucastrine 14 Kadlec and Robbins (1984) Fen Indiana 0.9 2 61 900 N and P data from Craft and Schubauer-Berigan (2006), C data from C. B. Craft (unpublished data) Michigan 0.2 1–9à 30 420 Graham et al. (2005), Richardson and Marshall (1986) Cedar swamp Michigan 0.3 36 950 C data from Craft et al. (2008); sediment, P, and N data from C. B. Craft (unpublished data) Bog Minnestoa 0.5 7–12 790–1980 Wieder et al. (1994), Urban and Eisenreich (1988) Michigan 0.3 80 1320 C data from Craft et al. (2008); sediment, P, and N data from C. B. Craft (unpublished data) Constructed marsh Illinois 5–128 4–29 130–380 Fennessy et al. (1994), Mitsch et al. (1995), Phipps and Crumpton (1994) Ohio 43–47 33–35 162–166 1525–1660 Anderson and Mitsch (2006) Iowa 368–1510 Crumpton et al. (2006) Note: Numbers in boldface represent accumulation in highly loaded wetlands. Calculated assuming C:N ¼ 20. à Richardson and Marshall (1986) found 9 kgha1yr1 from a fen receiving wastewater.

Not all constructed wetlands are as effective for es such as water storage, evapotranspiration, and pollutant removal. Sidle et al. (2000) reported that gradual release that augments stream base flow in dry wetlands constructed in the Kankakee River (Indiana) seasons (Brauman et al. 2007). Increasing wetland area were less effective for nitrate removal than natural in a watershed will almost always decrease its surface wetlands because of nonuniform subsurface flow and water discharge due to the effects of vegetation alone, short hydrologic residence time. For constructed and particularly forests (Brooks et al. 2006, Brauman et al. restored surface water wetlands to be effective, they 2007). For example, Novitski (1985), working in the must have high water storage capacity to retain nitrate Northeastern United States, found that peak flows were during high-discharge events, when greater than 50% of an average of 50% lower in watersheds with 4% or the nitrate is exported from adjacent uplands (Royer et greater wetland area compared to those with less al. 2006). wetland coverage. Models of the relationships between the flood storage capacity of wetlands as a percentage of Flood abatement total land area in a watershed and flood peak reduction Wetlands are known to regulate the movement of have shown a threshold of 10%, such that, in watersheds water through watersheds via a combination of process- with ,10% wetland area, even small additional losses in April 2011 WETLAND SERVICES IN THE GLACIATED PLAINS S57 area can have major effects on flood flows (Johnston et TABLE 3. Rates of denitrification in Midwestern wetlands. al. 1990). If wetlands make up 10% or more of a watershed, flooding is reduced and stream base flows are Denitrification rate better maintained; for instance, Hey and Philippi (1995) Wetland (kgha1yr1) Source calculated that restoring 5.3 million ha of wetlands in Floodplain the Upper Mississippi River watershed (10% of the land Minnesota 10 Zak and Grigal area of the watershed) could have stored enough water (1991) to accommodate the 1993 Mississippi floods, thereby Michigan ,0.1 Merrill and Zak substantially reducing the $16 billion in flood damages (1992) Michigan 22 Groffman and Tiejde that resulted. Beyond this, there are few direct estimates (1989) of the ability of wetlands to reduce flooding in the GIP, Wet meadow nor are there spatially explicit data available for Wisconsin 1–2 Goodroad and Keeney conservation wetlands that would allow calculation of (1984) the contribution of these sites in reducing runoff and Marsh downstream flooding. Wisconsin ,0.1 Goodroad and Keeney Research to increase our understanding of the (1984) aggregate effects of wetlands on flood flows would also Bog help define the most strategic placement of wetlands in a Minnesota 0.1 Urban et al. watershed to maximize these services. Based on acreage (1988) alone, the wetlands established through conservation Constructed marsh practices and programs to date may have relatively small Ohio 1.3 Hernandez and Mitsch effects at the large scale, but almost certainly have (2006) beneficial effects at the local scale, particularly in watersheds where the area of wetlands established is relatively high (Fig. 4). For instance, wetlands located in have found invertebrate species richness to be similar in headwater areas within a watershed can effectively abate natural and restored wetlands (e.g., Balcombe et al. flooding depending on the ratio of their storage relative 2005b). However, a study comparing macro-invertebrate to the volume of floodwater (Potter 1994). These community structure in restored and natural wetlands in landscape approaches to wetland services allow for the Ohio found significantly higher total taxa richness, setting of provisional targets for the restoration or particularly for chironomids, in the natural sites, with a enhancement of wetland acreage in flood-prone areas. higher relative abundance of dipterans and tolerant snails in the restored sites (Fennessy et al. 2004). In Biodiversity Wisconsin, Dodson and Lillie (2001) found that While there have been few systematic data collected zooplankton taxa richness was similar in natural (with on the establishment of animal species as a result of an average of 7.3 taxa per site) and restored wetlands wetland conservation practices, the available literature (7.2 taxa). In this study, taxa richness was positively indicates that the establishment of wetland-dependent correlated with time since restoration. species is rapid across many taxonomic groups including Bird species response to wetland restoration is invertebrates, herpetofauna,fish,andbirds(Rewa relatively well documented. Bird species are shown to 2005). In some cases, species richness has been shown rapidly colonize sites, and while reports vary, many to approach natural levels; for example, comparisons of projects report that avian species richness levels ap- natural with newly restored wetlands has shown that proach that of natural wetlands, including those of amphibian, avian, and invertebrate species richness was management concern in Iowa and migratory species in similar, or in some cases, higher in the created sites (e.g., Ohio (Mitsch et al. 1998, Fletcher and Koford 2003). A Balcombe et al. 2005a, b), although this is sometimes constructed wetland located on floodplain of the due to a predominance of nonnative or tolerant species. Olentangy River in Ohio provided habitat for a total With respect to these taxonomic groups (including of 126 bird species (wetland and adjacent terrestrial plants, which are not discussed here), there are no data habitat) by the fifth year following construction (Mitsch that allow us to fully describe the benefits of the various et al. 1998). wetland conservation practices, or to distinguish how The capacity of wetlands to support amphibian they might differ in habitat value. populations depends on both the conditions within the Despite the importance of macro-invertebrates in site and the characteristics of the surrounding landscape, wetlands, there are few studies documenting their including the presence of terrestrial forested buffers, successional patterns or community development. distance to nearest neighbor wetlands, road density, and Invertebrates are diverse both in terms of species presence of corridors connecting habitat areas (Knutson richness and the trophic levels they occupy (herbivores, et al. 1999, Lehtinen et al. 1999, Weyrauch and Grubb detritivores, predators/carnivores), and so they are 2004). Both road density and distance to the nearest involved in multiple ecosystem processes. Several studies neighbor wetlands in agricultural landscapes were S58 SIOBHAN FENNESSY AND CHRISTOPHER CRAFT Ecological Applications Special Issue significant predictors of amphibian species richness in ment stimulates peat accretion and C accumulation in the GIP (Lehtinen et al. 1999). wetland soils of the GIP and elsewhere (Craft and Microhabitats and trophic interactions affect species Richardson 1993). For example, in Indiana, a natural establishment. In a study of Ohio wetlands, Porej et al. floodplain marsh receiving treated wastewater seques- (2004) found that amphibian diversity was significantly tered three times more C (3700 kgha1yr1) than a higher in restored wetlands with shallows and without comparable unenriched floodplain marsh (1200 predaceous fish. Vegetated shallows are important for kgha1yr1) (Table 2). The effect of nutrient enrich- floral and faunal diversity and are nearly always present ment on CH4 emissions is in the GIP is largely unknown. in natural wetlands. The overall structure of the The pattern of carbon fluxes over the long term is amphibian community was also different in the restored important to the question of whether restored wetlands sites, with a dominance of some species, e.g., bullfrog will be a carbon sink. Bridgham et al. (2006) estimate (Rana catesbeiana), green frog (Rana clamitans), and that the historical destruction of wetlands (through toads, and the near absence of other species, such as drainage, et cetera) had the largest impact of carbon spring peepers (Pseudacris crucifer), western chorus fluxes, moving C from soil to the atmosphere. Until frogs (Pseudacris triseriata), and most salamanders. more data are available, where wetlands are created or Ultimately, wetland practices that provide sites with restored, their potential to sequester C should not be seasonal inundation and an upland buffer will provide overlooked (Table 2). habitat for herpetofauna. With this, as with other taxonomic groups, details on the relationships between CONTRIBUTIONS OF CONSERVATION PRACTICES wetland conservation practices, landscape characteris- TO WATER QUALITY IN THE GIP tics, and the provision of habitat are yet to be Wetlands serve an important role in nutrient man- determined. agement at the landscape scale. Restoring wetlands to improve water quality requires a landscape approach Carbon sequestration that maximizes the ability of sites to capture and process Soils are a major reservoir of organic matter and thus diffuse runoff. At the site-scale riparian zones, even an important sink of carbon. Compared to agricultural narrow bands (e.g., ,10 m) adjacent to streams, ditches, soils, which contain an average of 0.5–2% C with up to or rivers can remove up to 90% of N (Zedler and 5% C, wetland soils can accumulate up to 30–40% C Kercher 2005). Although relatively little is known about (Lal et al. 1995). Wetlands generally sequester carbon at the links between the placement of wetlands within a higher rates than terrestrial soils in the region, and peat- watershed and the accumulation of services at the accumulating wetlands, bogs, and to a lesser extent fens, watershed scale, the extent of wetland practices imple- have the greatest capacity to accumulate and store mented can be used to make an initial characterization carbon (Table 2). of the ecosystem services provided. The importance of Midwestern wetlands for carbon The degradation of water quality in the Upper sequestration has been understudied relative to terres- Mississippi has been extensively documented. In an trial ecosystems, where vast areas potentially are investigation of N loading to the Mississippi River, available for restoration. However, in the conterminous Goolsby et al. (1999) delineated 42 subwatersheds to United States, C sequestration in wetlands with mineral provide detailed information on N export and identify soils is estimated to be 5.3 Pg (1 Pg ¼ 1015 g ¼ 1 billion those with abnormally high outflows. Nitrogen was the metric tons), with 6.6 Pg stored in non-permafrost focus as it has been identified most responsible for peatlands, a small proportion of the 529 Pg of C stored hypoxia in the Gulf of Mexico (Rabalais et al. 2002). in wetland soils globally (Bridgham et al. 2006). Sixteen of these watersheds lie wholly or partially in the Floodplain wetlands in the region sequester C at rates GIP (Fig. 5), including some with the highest nutrient comparable to bogs and fens, whereas depressional export rates in the entire basin. For example, the upper wetlands have lower rates of C sequestration (Table 2). Illinois River exports more N per unit area than any Although wetlands sequester more carbon than other subwatershed in the Mississippi Basin, yielding terrestrial ecosystems per unit area, they occupy only a 3120 kg Nkm2yr1. This is followed by the Iowa and fraction of the Midwest landscape, and C sequestration Skunk Rivers at 2750 and 2290 kg Nkm2yr1, in soil is a slow process relative to biomass accrual. For respectively. this reason, wetlands are not considered an important We used estimates of the nutrient retention rates for short-term restoration strategy for sequestering carbon. the various wetland conservation practices (Table 2), There is also a trade-off between the capacity of along with an estimate of the area of wetland wetlands to absorb carbon dioxide and the fact that conservation practices implemented within the portion they are a source of methane, a potent greenhouse gas. of the GIP that lies in the Mississippi River watershed, Estimates vary, but it is possible that any gains in C to estimate their cumulative nutrient retention ability sequestration due to wetland restoration could be offset (Table 4). This provides an estimate of the cumulative by methane emissions (Bridgham et al. 2006). Further nutrient retention capacity of conservation wetlands put complications arise from the fact that nutrient enrich- in place through Farm Bill conservation programs (e.g., April 2011 WETLAND SERVICES IN THE GLACIATED PLAINS S59

FIG. 5. Overlap between the area of the Glaciated Interior Plains and the subbasins used to analyze nutrient export to the Mississippi River and the Gulf of Mexico. Subbasin boundaries are based on Goolsby et al. (1999).

WRP, CREP, CRP, Technical Assistance), and their The water quality benefits of nutrient interception can overall ability to reduce sediment, N, and P export to the also be made using estimates of the relative proportion Gulf of Mexico. Nutrient retention rates vary with the of nutrients that are generated within the GIP region type and acreage of wetlands involved. Reflecting their itself, calculated based on the proportion (15.8%) of the ability to process large amounts of N, riparian buffer GIP that lies within the Mississippi River watershed. In strips remove more N than any other practice, totaling this case, the estimated nutrient retention capacity of an estimated 6.5 million kg/yr. Wetland restoration conservation wetlands amounts to 6.8% of N, 4.9% of P, accounts for another 4.5 million kg/yr. In total, and 11.5% of the sediment exported from the region conservation practices are estimated to retain nearly annually. These estimates demonstrate the potential for 14.6 million kg/yr. The total annual load to the Gulf of reestablishing ecosystem services through conservation Mexico ranges between 1.5 and 1.6 million Mg of N practices based on wetland and riparian-zone establish- (Goolsby et al. 1999, Alexander et al. 2008); therefore, ment and management. the amount of N intercepted by conservation wetlands In response to hypoxia in the Gulf, nutrient manage- amounts to an estimated 1.0% of the total N reaching ment strategies were set forth in the ‘‘Action plan for the Gulf of Mexico annually. Given that most of the reducing, mitigating, and controlling hypoxia in the wetland area in the GIP was created over a three-year Northern Gulf of Mexico’’ (Mississippi River/Gulf of period (2004–2006), these estimates show the potential Mexico Watershed Nutrient Task Force 2001, Rabalais for the restoration of ecosystem services that are et al. 2002). The action plan established the goal of measurable at the watershed scale. reducing the five-year running average of the areal Sediment and P retention are also substantial. extent of the hypoxic zone to 5000 km2 or less by 2015. Wetland restoration projects account for the largest Initial estimates set the level of N load reductions needed sink for sediments: Collectively, these sites retain an to meet this goal at 30% below the 1980–1996 average estimated 1.5 million Mg of sediment annually (Table (Rabalais et al. 2002, Scavia et al. 2003). Subsequent 4), representing an estimated 1.8% of the total sediment models developed during a reassessment of the action load that flows from the Mississippi River each year. plan, required every five years, have shown that, while a Phosphorus retention is estimated to account for 0.8% 30% reduction in N loads would lead to a 20–60% of the total annual load in the Mississippi River. reduction in the extent of hypoxia, it will require a 40– S60 SIOBHAN FENNESSY AND CHRISTOPHER CRAFT Ecological Applications Special Issue

TABLE 4. Estimated annual nutrient retention rates (with percentages of nutrient load) for NRCS conservation practices located in the Mississippi River Basin portion of the Glaciated Interior Plains (GIP) for those wetlands established or managed over the period 2000–2006.

Sediment Nitrogen Phosphorus Carbon Total area retained retained retained retained Practice implemented (ha) (Mg/yr) (kg/yr)à (kg/yr)§ (kg/yr)} Constructed Wetland 22 1083 3250 433 10 833 Riparian Buffers 13 120 656 010 6 560 105 131 202 6 560 105 Wetland Creation 1007 50 341 151 023 20 136 503 408 Wetland Enhancement 3030 30 297 302 974 30 297 1 514 868 Wetland Restoration 30 190 1 509 508 4 528 523 603 803 15 095 076 Wetland Wildlife Habitat Management 30 284 302 837 3 028 373 302 837 15 141 867 Total 77 652 2 550 077 14 574 247 1 088 710 38 826 157 Percentage of total nutrient load in NA 1.8# 1.0|| 0.8 ... Mississippi River retained Relative percentage of nutrient load NA 11.5 6.8 4.9 ... from GIP region retained Note: Conservation practice area data were supplied by NRCS. NA indicates not applicable; ellipses indicate that data were not available. Assumes mean retention rate of 50 Mgha1yr1;10Mgha1yr1 for enhancement and wildlife habitat activities (see Table 2). à Assumes mean retention of 500 kgha1yr1for riparian buffers; 150 kgha1yr1 for constructed, created, and restored wetlands; and 100 kgha1yr1 for enhancement and wildlife habitat (see Table 2). § Assumes mean retention rate of 10 kgha1yr1 for riparian buffers; 20 kgha1yr1 for constructed, created, and restored wetlands; and 10 kgha1yr1 for enhancement and wildlife habitat (see Table 2). } Assumes mean retention rate of 500 kgha1yr1 (see Table 2). # Assumes mean annual sediment export of 144 million Mg to the Gulf of Mexico. jj Assumes mean annual N export of 1.4 million Mg to the Gulf of Mexico. Assumes mean annual P export of 0.14 million Mg to the Gulf of Mexico.

45% nitrogen load reduction to meet the 5000 km2 goal basin) could reduce nitrate loadings to the Gulf of (Scavia et al. 2003, Justic et al. 2007, Scavia and Mexico by 300–800 3 103 Mg/yr, or by 18–50%, based Donnelly 2007). Of the 31 states that contribute to the on annual loads of 1.5–1.6 million Mg/yr. Likewise, Hey Mississippi River flow, nine states (Illinois, Iowa, and Philippi (1995) recommended that 5.3 million ha of Indiana, Missouri, Arkansas, Kentucky, , restored wetlands would hold the floodwater equal to Ohio, and Mississippi) deliver 75% of the total N and the 1993 Mississippi River flood. An earlier study called P to the Gulf of Mexico (Alexander et al. 2008). The for the restoration or creation of 10 million ha of GIP contains all or parts of five of these nine states wetlands and riparian zones (3.4% of the basin), (Illinois, Iowa, Indiana, Missouri, and Ohio). A focused concluding that this would reduce nitrogen in the river program of wetland restoration in the GIP region has by an estimated 40% (Mitsch et al. 1999). Extrapolating the potential to reduce seasonal hypoxia by helping to from our broad estimates of the N removed by NRCS meet targets for reductions in nutrient exports. conservation practices (Table 4), ;1.3 million ha (;3.1 One component of a watershed-based approach to million acres) would be required to achieve a 40% accomplish the goal of protecting downstream water reduction in N. While these numbers will undoubtedly quality is to promote large-scale efforts to create and be refined, these studies place the need for restoration at restore wetlands (Table 5). Mitsch et al. (2001) estimated between 3 and 10 million ha, or 1.0–3.4% of the land that the creation and restoration of 2.1–5.3 million ha of area of the basin. If reductions in N loads of 40% could wetlands in the Mississippi River Basin (0.7–1.8% of the be achieved, the analysis conducted as a result of the

TABLE 5. Estimates of riparian/wetland area needed to significantly improve the water quality of receiving waters.

Percentage of watershed Reduction Activity and location converted in load (%) Source Riparian restoration (USA) 0.7–1.8 19–50 (N) Mitsch et al. (2001) Wetland creation and restoration (USA) 2.7–6.6 19–50 (N) Mitsch et al. (2001) Wetland creation and restoration (USA) 5 46 (N) Kovacic et al. (2006) Wetland creation and restoration (Sweden)à 5–10 25–50 (N) Tonderski et al. (2005) 34–68 (P) Wetlands (China) ;5 .90 (P) Verhoeven et al. (2006) Note: Abbreviations are: N, nitrogen; P, phosphorus. All activities in the United States were carried out in the Mississippi River Basin. à Involves conversion of arable land to wetland. April 2011 WETLAND SERVICES IN THE GLACIATED PLAINS S61 action plan indicates that this could help meet Gulf of Mexico water quality goals. The spatial distribution of conservation projects will be a key factor in successfully reducing nutrient loads in surface waters. By targeting restoration in certain high- nutrient watersheds like the Illinois River Basin, even greater reductions could be achieved with less effort (Mitsch et al. 2001, Kovacic et al. 2006). While studies to quantify the effects of the spatial distribution of conservation practices within a watershed are underway in projects such as the NRCS ‘‘benchmark’’ watershed studies (King et al. 2008), results to date are limited and questions remain on the watershed-scale benefits of project implementation. One crucial question regarding ecosystem services is FIG. 6. Correlation between the N export from the whether the implementation of conservation practices subbasins shown in Fig. 5 (data from Goolsby et al. [1999]) coincides with areas that are in most need of restoration, and the area of wetland conservation practices (i.e., Wetland Creation, Wetland Restoration, Wetland Enhancement, such as locating conservation wetlands appropriately to Wetland Wildlife Habitat Management, and Riparian Forest treat high-nutrient runoff. Using the subwatersheds to Buffer) implemented in each watershed through Farm Bill evaluate nutrient export to the Mississippi River conservation programs between 2000 and 2006. (Goolsby et al. 1999), we found a strong correlation (r ¼ 0.81) between the total area of NRCS conservation and how the spatial distribution of conservation practices implemented between 2000 and 2006 and the practices on the landscape affects the delivery of those estimated nitrogen export from each subwatershed prior services. In many cases landowners have choices about to the implementation of these projects (Fig. 6), which practices might best suit their land or needs. suggesting that, at least for water quality improvement, Decision making of this sort would be strengthened if we conservation practices are successfully targeting water- understood the trade-offs in the relative degree of sheds that are exporting the most N. At its best, the services delivered by one conservation practice (e.g., provision of ecosystem services through implementation wetland restoration) over another (wetland wildlife of wetland conservation practices will result in improved habitat management). At this point there is no means environmental quality and human health in terms of to distinguish the benefits provided by individual improved downstream water quality. What is lacking in practices or the trade-offs between the provisioning of the GIP is specific data to demonstrate that these different ecosystem services (e.g., water purification vs. conservation practices are measurably decreasing N biodiversity support). This is particularly true for export at the subwatershed scale, and whether or not carbon sequestration and potential changes in carbon wetlands are being sited within watersheds in ways that dynamics due to altered nutrient loadings and issues maximize water quality improvement (White and related to climate change (e.g., CH4 emissions). Future Fennessy 2005). establishment of conservation projects might take advantage of the opportunity to impose whole water- CONCLUSIONS shed experiments by systematically testing the effects of More than 80% of the acreage involving Wetland the quantity and spatial distribution of wetland projects Restoration, Creation, Enhancement, the establishment (or lack thereof) on a subwatershed basis. This of Riparian Forest Buffers, and Wetland Wildlife approach is being used in several of the NRCS Habitat Management conservation practices implement- benchmark studies designed to investigate the benefits ed in the period between 2000 and 2006 was put in place of watershed-scale restoration (King et al. 2008). in just three years (2004–2006), demonstrating the Focusing research on these questions will help us potential for wetland practices to rapidly restore determine whether, and to what extent, wetland and ecosystem services that are measurable at the watershed riparian restoration projects on agricultural lands are scale. However, many subwatersheds in the Glaciated providing critical wetland ecosystem services. Interior Plains were untouched by these practices and ACKNOWLEDGMENTS associated Farm Bill conservation programs; thus, they We thank Diane Eckles for her unflagging support, help with offer the potential for further conservation efforts to be data, and patience with queries throughout the process. We implemented in the region. The preliminary results dedicate this paper to her as she completes more than 30 years presented here indicate generally that the quantity of of service to federal conservation programs. Susan Wallace and ecosystem services delivered regionally can be increased Peter Chen are gratefully acknowledged for assistance with GIS analysis and mapping. S. Fennessy is indebted to Hugh Prince, over remarkably short time periods. Our analysis points of University College London, Department of Geography, for to the need for indicators that can document the ability formative conversations on the environmental history of of conservation practices to deliver ecosystem services wetlands in the Midwest. This project was funded in part by S62 SIOBHAN FENNESSY AND CHRISTOPHER CRAFT Ecological Applications Special Issue

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