Geology topics

Research about Iowa, Minnesota, Wisconsin

Source-linked reports with geographic coverage including Iowa, Minnesota, Wisconsin.

11 recordsLinked to original sources

USGS2026

Blanchard's cricket frogs (Acris blanchardi) have re-expanded northward since mid-2000s: Landscape predictors of occupancy

Blanchard's Cricket Frogs ( Acris blanchardi ) declined along their northern range edge in the upper Midwest in the mid-to late 1900s. The causes of these declines remain poorly understood, as does the current status of this species and their habitat requirements. In 2024, we revisited more than 300 locations previously sampled between 2003 and 2008 along this range edge in Minnesota, Wisconsin, Iowa, and Illinois. We conducted roadside anuran call surveys at each site and extracted land cover information from the National Land Cover Database and a global stream layer. We developed a multi-species occupancy model, which included imperfect detection, species traits, and species associations, to test for changes in occupancy through time and determine whether environmental characteristics were associated with cricket frog presence. Blanchard's Cricket Frogs occupied more sites and occurred farther north in 2024 relative to the mid-2000s, suggesting a partial recolonization in the zone of previous decline. Forest, croplands, and latitude were negatively associated with cricket frog occupancy, whereas wetlands, river size, and development did not have strongly supported effects. Species associations implied that wetland permanence could have been an important determinant of occupancy, but we did not have this covariate information for many of our sites due to private ownership of surrounding lands. Causes of earlier declines remain largely unknown, and many previously occupied regions apparently remain devoid of cricket frogs. However, some populations have been expanding northward over the past two decades in the upper Midwest.

Iowa, Minnesota, Wisconsin↗

USGS2026

Drift and dispersion of silver carp (Hypophthalmichthys molitrix) eggs and larvae for hypothetical spawning scenarios in the Upper Mississippi River

Invasive carp pose ecological and economic risks to North American freshwater systems. This study uses the Fluvial Egg Drift Simulator to model the drift of invasive silver carp ( Hypophthalmichthys molitrix) eggs and larvae after hypothetical spawning in Pools 1–10 of the Upper Mississippi River. Although adult invasive carps have been detected in this region, no reproduction has been confirmed as of this publication. A total of 450 spawning scenarios were simulated, representing 5 water temperatures, 9 flows, and 10 spawning locations in the tailwaters of lock and dam structures. The study examined egg and larval positions at two key developmental stages: hatching and gas bladder inflation, when larvae seek nursery habitat. Under a wide variety of flow conditions and water temperatures, eggs spawned upstream from Lake Pepin (Pool 4) are likely to settle in the lake before hatching, possibly increasing mortality rates. Eggs that survive passage through Lake Pepin reach gas bladder inflation within the study area, except in scenarios with lower temperatures and higher flows. Conversely, larvae spawned downstream from Lake Pepin generally drift out of the study area before reaching gas bladder inflation, except in cases of higher temperatures and lower flows. These findings inform ichthyoplankton sampling strategies and management actions aimed at reducing invasive carp populations in areas likely to support recruitment.

Iowa, Minnesota, Wisconsin↗

USGS2025

Future forest conditions under alternative management and hydrological scenarios in the Upper Mississippi River floodplain

Context Floodplain forests are being transformed by multiple pressures, prompting widespread management and restoration efforts. It is uncertain how disturbances, including hydrologic change, and management actions will interact to influence the ecology of these threatened forests. Objectives This study examined the effects of alternative management and hydrologic regimes on forest succession at an Upper Mississippi River floodplain site with a restoration project in planning. Methods We used the spatially explicit forest landscape model, LANDIS-II, to simulate forest succession for 100 years under four hydrogeomorphic management scenarios, three forest management scenarios, and two scenarios of future hydrologic conditions. We evaluated changes in forest biomass and composition over time and assessed the relative importance of management actions and hydrologic change on succession. Results Forest aboveground biomass decreased in all management-hydrology scenarios, especially in the wetter hydrological scenario. Intensified hydrogeomorphic and forest management scenarios reduced the magnitude and extent of biomass declines; however, they were unable to prevent overall declines in biomass or cause large shifts in tree species composition. Silver maple ( Acer saccharinum ) was projected to decrease in biomass, while increases in biomass were projected for several late-successional species including swamp white oak ( Quercus bicolor ). Among the factors influencing variation in biomass, forest management had the largest influence in the first 50 years of our simulations, but hydrological regime became the most important factor by the end of the century. Conclusions Our simulations indicate that management actions could play an important role in the conservation of floodplain forests, but their effectiveness will likely be limited if recent upward trends in flooding conditions in this system continue in the future. Thus, our results highlight both the potential benefits and limitations of management actions in the face of hydrologic change.

Iowa, Minnesota, Wisconsin↗

USGS2024

Identifying conditions where reed canarygrass (Phalaris arundinacea) functions as a driver of forest loss in the Upper Mississippi River floodplain under different hydrological scenarios

Most of the world’s river-floodplain ecosystems are simultaneously undergoing modifications to their hydrological regimes and experiencing species invasions, making it unclear whether invasive species are the main drivers of ecosystem change or simply responding to changes in the hydrological regime. We simulated patterns of forest recruitment and succession in a 2500-ha portion of the Upper Mississippi River floodplain with and without removal of invasive Phalaris arundinacea and under two different future 100-year hydrological scenarios: a future maintaining the average flooding conditions of the past 40 years (random) and a future that projects an observed upward 40-year trend in flooding conditions forward (trending). By comparing scenarios that included Phalaris removal and ones that did not, we were able to identify the conditions where Phalaris was the main driver of forest loss vs. the conditions where hydrology was the main driver of forest loss. Areas where Phalaris was the main driver of forest loss had mean annual flood inundation durations that were similar to areas that did not lose forest cover (60–90 growing season days), while areas where flooding was the main driver of forest loss had longer mean inundation durations (102–124 growing season days). In comparison to the random hydrology scenario, the trending scenario produced a decrease in the area over which Phalaris was identified as the main driver of forest loss and an increase in the area over which flood inundation was identified as the main driver of forest loss. Thus, if the observed trends in flooding continue, our model projects an increase in the area over which eradicating Phalaris is unlikely to result in the maintenance of forest cover. We used the Resist-Accept-Direct (RAD) framework to discuss potential management options to resist changes and maintain forest cover where Phalaris is likely to be the main driver of forest loss and to accept or direct changes in areas where forest loss is likely driven by hydrological change.

Iowa, Minnesota, Wisconsin↗

USGS2023

22 years of aquatic plant spatiotemporal dynamics in the upper Mississippi River

Macrophyte (aquatic plant) recovery has occurred in rivers worldwide, but assemblage patterns and habitat requirements are generally not well understood. We examined patterns of species composition and macrophyte abundance in the Upper Mississippi River (UMR), spanning 22 years of monitoring and a period of vegetation recovery. Non-metric multidimensional scaling (NMDS) ordination revealed a gradient of macrophyte abundance and diversity for 25 species, which were associated with water velocity, depth, wind fetch, and water clarity. Three macrophyte genera of ecological and restoration interest ( Zizania aquatica , Vallisneria americana , and Sagittaria spp.) occupied different ecological niches. Trends of NMDS values showed that Z. aquatica first co-occurred in shallow areas with Sagittaria spp. but then expanded into deeper, lotic habitats where V. americana often resided. Curve Fit regression analysis identified large areas of significant increases in the relative abundance of V. americana and percent cover of Z. aquatica in several reaches of the UMR from 1998–2019. Sagittaria spp. were more spatiotemporally dynamic, which may indicate specific habitat requirements and sensitivity to environmental gradients. Our analyses showed that these three ecologically important genera are spatiotemporally dynamic but have somewhat predictable habitat associations, which can guide macrophyte management and restoration in the UMR and other large, floodplain rivers.

Iowa, Minnesota, Wisconsin↗

USGS2022

What is a stand? Assessing the variability of composition and structure in floodplain forest ecosystems across spatial scales in the Upper Mississippi River

The forest stand typically represents relatively homogenous forest conditions; the forest stand is generally the unit at which forest attributes are assessed, summarized, and subsequently managed. However, some ecosystems, such as the floodplain forests of the Upper Mississippi River (UMR), can exhibit high variability at fine spatial scales that can confound prescription development, implementation, and ultimate success of stand-level management actions. Here we assess how forest composition and structure vary within and across stand management units on the UMR and test at what spatial scale environmental variables relate to forest characteristics. We found that plot-level measures of composition, structure, and diversity were not well represented by site-level averages of these values. When basal area of all overstory species was combined, this variable was more closely related to “site” than to any of the environmental variables, but when analyzed by species, within-plot topographic variation (“microtopography”) was a significant positive predictor for both importance values of an individual species (swamp white oak ( Quercus bicolor Willd.)) as well as importance value of a specific group of species (oaks (Quercus spp.), bitternut hickory ( Carya cordiformis (Wangenh.) K. Koch), hackberry ( Celtis occidentalis L.), and American basswood ( Tilia americana L.)). This work highlights the challenges of using average stand conditions to summarize complex or heterogeneous systems and the need for flexibility and relaxed assumptions in defining management units in these forests.

Iowa, Minnesota, Wisconsin↗

USGS2021

Broadscale population structure and hatchery introgression of Midwestern brook trout: Midwestern brook trout population genetics

Brook Trout Salvelinus fontinalis have faced significant declines throughout their native range and have been stocked in Midwestern waters since the late 1800s to offset such losses. Several studies have investigated the genetic effects of these stockings, but these efforts have been confined to relatively small spatial scales. In this study, we compiled 8,454 Brook Trout microsatellite genotypes from 188 wild Midwestern populations and 26 hatchery strains to provide novel insights of broadscale population structure, regional patterns of genetic diversity, and estimates of hatchery introgression for inland Wisconsin populations. Our results indicate high levels of differentiation among our study populations, a lack of hydrological population structuring, lower estimates of genetic diversity in the Driftless Area, and that hatchery introgression has been largely confined to regions of inland Wisconsin that have been heavily affected by anthropogenic disturbances (i.e., the Driftless Area). We also provide evidence that populations may be able to purge hatchery‐derived alleles, discuss possible mechanisms behind this phenomenon, and consider their relevance to accurate estimation of hatchery introgression. Collectively, these results summarize the genetic effects of over a century of anthropogenic disturbance on native Brook Trout populations and emphasize the importance of integrating historical data into contemporary genetic research of intensively managed species.

Iowa, Minnesota, Wisconsin↗

USGS2021

Anthropogenic landcover impacts fluvial dissolved organic matter composition in the Upper Mississippi River Basin

Landcover changes have altered the natural carbon cycle; however, most landcover studies focus on either forest conversion to agriculture or urban, rarely both. We present differences in dissolved organic carbon (DOC) concentrations and dissolved organic matter (DOM) molecular composition within Upper Mississippi River Basin low order streams and rivers draining one of three dominant landcovers (forest, agriculture, and urban). Streams draining forest and urban landcovers have greater DOC concentrations, likely driven by differences in carbon sourcing, microbial processing, and soil disturbance. Using Fourier transform-ion cyclotron resonance mass spectrometry, 24% of assigned molecular formulae are common across all landcovers. Relative abundances of N-,S- heteroatomic formulae (CHON, CHOS, CHONS) are higher for agricultural and urban streams, with agricultural stream DOM having more N-containing formulae compared to urban stream DOM, which has more S-containing formulae. Higher N-,S- heteroatomic formulae abundance, along with enrichment in aliphatic, N-aliphatic, and highly unsaturated and phenolic (low O/C) compound categories within agricultural and urban stream DOM are likely to result from increased anthropogenic inputs, autochthonous production, and microbial processing associated with agricultural and urban impacts. Reduced N-,S- heteroatomic formulae abundances in forested stream DOM, along with enrichments in condensed aromatics, polyphenolics, and highly unsaturated phenolic (high O/C) compound categories, likely reflect greater contributions from surrounding organic-rich forest soil and vegetation. Overall, landcover change from forested to agriculture lowers DOC concentrations and changes from forested to agriculture or urban increases autochthonous, and presumably more biolabile, DOM contributions with ramifications for stream biogeochemical cycling.

Iowa, Minnesota, Wisconsin↗

USGS2020

Remnant hardwood forest mapping within the Upper Mississippi River floodplain

Executive Summary The primary objective of the project was to locate previously unknown stands of mast-producing hardwood forest trees in the Upper Mississippi River floodplain using existing information. We located and mapped 399 previously unknown hardwood forest stands within the Mississippi River floodplain area of navigation pools 9, 10, and 11. Using color infrared images in combination with true-color imagery was useful for identifying hardwood forest stands. We recommend our result be refined by visiting the forest stands we identified to evaluate our classification rate and determine which stands are regenerating. In combination with regeneration information, our results can help better inform flood inundation modeling, which will help improve the efficacy of restoration design. Although we had some success using the best available information, to obtain more relevant observations, we recommend acquiring color infrared aerial imagery during the late fall season if providing detailed mapping of forest stands is a management priority. Imagery of this type collected in the fall, when trees may be distinguished by their differing senescence, has the potential to uniquely identify individual species or perhaps even individual trees. Gaining a better understanding of forest diversity and developing conservation strategies to preserve that diversity is timely because remaining aging trees, established before lock-and-dam installation on the Mississippi River, are nearing the end of their life expectancy.

Iowa, Minnesota, Wisconsin↗

USGS2002

Evaluation of spatial models to predict vulnerability of forest birds to brood parasitism by cowbirds

We constructed alternative spatial models at two scales to predict Brown-headed Cowbird ( Molothrus ater ) parasitism rates from land cover maps. The local-scale models tested competing hypotheses about the relationship between cowbird parasitism and distance of host nests from a forest edge (forest-nonforest boundary). The landscape models tested competing hypotheses about how landscape features (e.g., forests, agricultural fields) interact to determine rates of cowbird parasitism. The models incorporate spatial neighborhoods with a radius of 2.5 km in their formulation, reflecting the scale of the majority of cowbird commuting activity. Field data on parasitism by cowbirds (parasitism rate and number of cowbird eggs per nest) were collected at 28 sites in the Driftless Area Ecoregion of Wisconsin, Minnesota, and Iowa and were compared to the predictions of the alternative models. At the local scale, there was a significant positive relationship between cowbird parasitism and mean distance of nest sites from the forest edge. At the landscape scale, the best fitting models were the forest-dependent and forest-fragmentation-dependent models, in which more heavily forested and less fragmented landscapes had higher parasitism rates. However, much of the explanatory power of these models results from the inclusion of the local-scale relationship in these models. We found lower rates of cowbird parasitism than did most Midwestern studies, and we identified landscape patterns of cowbird parasitism that are opposite to those reported in several other studies of Midwestern songbirds. We caution that cowbird parasitism patterns can be unpredictable, depending upon ecoregional location and the spatial extent, and that our models should be tested in other ecoregions before they are applied there. Our study confirms that cowbird biology has a strong spatial component, and that improved spatial models applied at multiple spatial scales will be required to predict the effects of landscape and forest management on cowbird parasitism of forest birds.

Iowa, Minnesota, Wisconsin↗

USGS2000

Patterns of artificial nest depredation in a large floodplain forest

We used artificial bird nests to examine the relative effects of local habitat features and the surrounding landscape on the probability of songbird nest depredation in floodplain forests of the Upper Mississippi River. We found that the probability of depredation increased with size of floodplain forest plots. In small plots, the probability of depredation tended to increase away from the forest edge. Small patches of floodplain forest within a large river system can provide valuable nesting habitat for songbirds. We suggest that depredation pressure may be lower due to isolation effects. The probability of nest depredation increased with increasing canopy cover surrounding the nest tree and decreasing cover around the nest. Managers seeking to discourage nest predators in floodplain forests should consider managing for habitats that supply dense cover for nest concealment and an open tree canopy.

Iowa, Minnesota, Wisconsin↗