Northern Wisconsin Research Articles

How Forest Structure Drives Productivity

Data from northern Wisconsin forest sites uncovered that vertical heterogeneity metrics are the most influential factors underlying rates of photosynthesis.

Spread rates do not necessarily predict outbreak dynamics in a broadly distributed invasive insect

Biological invasions by insects entail several processes including spread and outbreaks that can cause widespread tree mortality. These processes are commonly viewed as a linear sequence because we often lack the mechanistic understanding needed to partition them. We explored an invasion that occurred over a large enough spatial scale and time frame to examine the conditions under which spread rates may be uncoupled from outbreak severity. Lymantria dispar is an invasive generalist folivore that has spread continuously from its initial point of introduction in North America at variable rates. Since its establishment in Wisconsin, USA in 1998, L. dispar has spread more rapidly there than any other region, but has never irrupted into regionwide outbreaks. In contrast, L. dispar spread more slowly elsewhere, in part due to strong mate-finding Allee effects, but periodically undergoes highly damaging, landscape-scale outbreaks in susceptible forest types. We conducted a 10-year study across 45 stands in northern Wisconsin with a high composition of favorable hosts. We quantified population trends of life stages, natural enemy abundance and impacts, and radial tree growth increment, and assessed biotic and abiotic factors as putative drivers of the decoupling between spread rates and outbreak severity. We then compared the results from these rapid-spread, low-impact sites with those from slow-spread, high-impact sites in Michigan and Pennsylvania, USA. The abundance and richness of natural enemy communities in Wisconsin were either equivalent to or less than those communities reported elsewhere, reducing the likelihood that greater top-down control explains the absence of outbreaks. We also found no differences in larval developmental time or drought that could increase the effects of natural enemies among the different regions. Rather, higher overwintering mortality due to more extreme and frequent lethal minimal temperatures in Wisconsin appeared most responsible for the lack of outbreaks. Overall, it appears that the combination of strong mate-finding Allee effects and low overwintering mortality elsewhere is a more substantial hindrance to spread than are weak mate-finding Allee effects and high overwintering mortality in Wisconsin. Once populations are established, the net contributions of these constraints become reversed: mate-finding limitations become only a minimal challenge whereas regional differences in winter survival best explain differences in outbreak frequency. These results suggest that spread rates of invasive insects should not be used as a proxy for predicting their local or overall impact, and that management efforts should be tailored to underlying processes determining their region-specific relative importance.

Unraveling Forest Complexity: Resource Use Efficiency, Disturbance, and the Structure‐Function Relationship

AbstractStructurally complex forests optimize resources to assimilate carbon more effectively, leading to higher productivity. Information obtained from Light Detection and Ranging (LiDAR)‐derived canopy structural complexity (CSC) metrics across spatial scales serves as a powerful indicator of ecosystem‐scale functions such as gross primary productivity (GPP). However, our understanding of mechanistic links between forest structure and function, and the impact of disturbance on the relationship, is limited. Here, we paired eddy covariance measurements of carbon and water fluxes from nine forested sites within the 10 × 10 km CHEESEHEAD19 study domain in Northern Wisconsin, USA with drone LiDAR measurements of CSC to establish which CSC metrics were strong drivers of GPP, and tested potential mediators of the relationship. Mechanistic relationships were inspected at five resolutions (0.25, 2, 10, 25, and 50 m) to determine whether relationships persisted with scale. Vertical heterogeneity metrics were the most influential in predicting productivity for forests with a significant degree of heterogeneity in management, forest type, and species composition. CSC metrics included in the structure‐function relationship as well as driver strength was dependent on metric calculation resolution. The relationship was mediated by light use efficiency (LUE) and water use efficiency (WUE), with WUE being a stronger mediator and driver of GPP. These findings allow us to improve representation in ecosystem models of how CSC impacts light and water‐sensitive processes, and ultimately GPP. Improved models enhance our capacity to accurately simulate forest responses to management, furthering our ability to assess climate mitigation strategies.

Evaluating convective planetary boundary layer height estimations resolved by both active and passive remote sensing instruments during the CHEESEHEAD19 field campaign

Abstract. During the Chequamegon Heterogeneous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors 2019 (CHEESEHEAD19) field campaign, held in the summer of 2019 in northern Wisconsin, USA, active and passive ground-based remote sensing instruments were deployed to understand the response of the planetary boundary layer to heterogeneous land surface forcing. These instruments include radar wind profilers, microwave radiometers, atmospheric emitted radiance interferometers, ceilometers, high spectral resolution lidars, Doppler lidars, and collaborative lower-atmospheric mobile profiling systems that combine several of these instruments. In this study, these ground-based remote sensing instruments are used to estimate the height of the daytime planetary boundary layer, and their performance is compared against independent boundary layer depth estimates obtained from radiosondes launched as part of the field campaign. The impact of clouds (in particular boundary layer clouds) on boundary layer depth estimations is also investigated. We found that while all instruments are overall able to provide reasonable boundary layer depth estimates, each of them shows strengths and weaknesses under certain conditions. For example, radar wind profilers perform well during cloud-free conditions, and microwave radiometers and atmospheric emitted radiance interferometers have a very good agreement during all conditions but are limited by the smoothness of the retrieved thermodynamic profiles. The estimates from ceilometers and high spectral resolution lidars can be hindered by the presence of elevated aerosol layers or clouds, and the multi-instrument retrieval from the collaborative lower atmospheric mobile profiling systems can be constricted to a limited height range in low-aerosol conditions.

Outbreak Investigation: Jamestown Canyon Virus Surveillance in Field-Collected Mosquitoes (Diptera: Culicidae) From Wisconsin, USA, 2018-2019.

During the summers of 2017–2019, 60 human cases of Jamestown Canyon virus-associated disease were reported in the State of Wisconsin, U.S.A; by comparison, there were 28 cases in the 5 years prior. Jamestown Canyon virus (JCV, Peribunyaviridae: Orthobunyavirus) is a zoonotic, mosquito-borne virus that is endemic throughout North America. The proposed transmission cycle for JCV involves horizontal transmission by a variety of mammal-feeding mosquito species and deer hosts, and transseasonal maintenance by vertical transmission in Aedes mosquito species. Although some of the earliest work on JCV transmission and disease was done in Wisconsin (WI), little is known about the spectrum of mosquitoes that are currently involved in transmission and maintenance of JCV, which is key to inform the approach to control and prevent JCV transmission, and to understand why case numbers have increased dramatically in recent years. Therefore, we undertook an intensive surveillance effort in Sawyer and Washburn counties, WI between April and August of 2018 and 2019, in an area with a concentration of JCV human cases. Larval and adult stages of mosquitoes were surveyed using larval dippers and emergence traps, light traps, resting boxes, a Shannon-style trap, and backpack aspirator. In total, 14,949 mosquitoes were collected in 2018, and 28,056 in 2019; these specimens represent 26 species in 7 genera. Suspect vector species were tested for JCV by polymerase chain reaction (PCR); of 23 species that were tested, only Aedes provocans yielded JCV positive results. In 2018, a single pool of Ae. provocans tested positive. In 2019, with more focused early season surveillance, we detected JCV in 4 pools of adult mosquitoes, and one pool that consisted of lab-raised adults that were collected as larvae. Material from all of these PCR-positive samples also yielded infectious virus in cell culture. Overall, these data provide new insight into the seasonality and habitat preferences for 26 mosquito species in Northern WI, which will be useful to inform future surveillance efforts for JCV. The results underscore the importance of Ae. provocans as a vector species involved in transseasonal maintenance of JCV in this region.

Rural Consciousness and Framing Environmental (In)Justice

Both rural regions and urban communities of color are often the target for unwanted land uses in the United States. However, although both types of communities will often organize resistance to the siting of environmentally hazardous facilities within their region, the frames that the activists use may differ dramatically. In this study, we examine a case study of environmental conflict over a proposed industrial hog farm in northern Wisconsin. We use that conflict to explore the claims making and rhetoric employed by the rural, predominantly white resistance. We argue that although communities of color and urban communities tend to utilize the environmental justice frame to understand and represent their resistance to unwanted land uses, rural communities that are predominantly white may instead frame their own resistance as a defense of rural identity and place. This study makes important contributions to our understanding of rural ideology and the environmental justice movement.

Investigating the Impacts of Daytime Boundary Layer Clouds on Surface Energy Fluxes and Boundary Layer Structure During CHEESEHEAD19

AbstractStudies of land‐atmosphere interactions under a clear sky and low cumulus cloud conditions are common from long‐term observatories like at the southern great plains. How well the relationships and responses of surface radiative and turbulent heat fluxes determined from these investigations hold for more heterogeneous surfaces in other climate regimes, however, is uncertain. In this study, detailed observations of the surface energy budget and daytime boundary layer properties are analyzed using measurements from the Chequamegon Heterogenous Ecosystem Energy‐Balance Study Enabled by a High‐Density Extensive Array of Detectors 2019 (CHEESEHEAD19) field campaign, July‐October 2019, across a heterogeneous forested landscape of northern Wisconsin. A cloud regime framework is employed to classify consecutive periods of clear skies from lower atmosphere stratiform and cumulus clouds. A seasonal transition from low cumulus to low stratiform periods occurred, together with a diurnal pattern in cloudy or clear sky period dominance. Radiative forcing was highly dependent on sky conditions, leading to changes in the redistribution efficiency of radiative energy by the surface turbulent heat fluxes. During CHEESEHEAD19, small Bowen ratios dominated with daytime latent heat fluxes three times as large as sensible heat fluxes for all sky conditions studied; the forested region, therefore, falls within an energy‐limited regime. The depth of the daytime mixed layer depended upon the sky condition and thermodynamic setting; deeper mixed layers occurred during periods of low cumulus and not clear skies. Profiles of vertical velocity were found to have enhanced variance under low cumulus compared to clear sky periods, suggesting potential for cloud feedbacks on boundary layer structure and surface energy fluxes.

Benthic–limnetic morphological variation in fishes: Dissolved organic carbon concentration produces unexpected patterns

AbstractVariation in traits related to foraging and locomotion in benthic and limnetic habitats has been observed in many fishes. Benthic and limnetic food chain productivity in lakes is strongly influenced by the concentration of dissolved organic carbon (DOC) in the water, suggesting that DOC might indirectly impose selection on these traits and lead to classic benthic forms at low DOC concentrations and limnetic forms at high DOC concentrations. We tested this hypothesis via geometric morphometric and meristic analyses of bluegill sunfish (Lepomis macrochirus, Centrarchidae) from 14 lakes with DOC concentrations ranging from 4 to 24 mg/L. These lakes, located in close proximity to each other, straddle the drainage divide between the Mississippi River and Laurentian Great Lakes basins in northern Wisconsin, USA. Bluegill morphology was consistently related to lake DOC concentration in both drainage basins, despite differences in morphology between basins. Fish from higher DOC lakes had deeper bodies and smaller heads, among other differences, though the proportion of shape variation described by DOC was low. Gill raker length and inter‐raker spacing were positively related to DOC concentration. Although some traits were thus related to DOC concentration, the directions of these relationships did not match the predicted benthic–limnetic patterns. Further, no relationships were evident between DOC and gill raker number, eye width, pectoral fin dimensions, or pectoral fin insertion angle in univariate analyses. These variable outcomes suggest that selection linked to DOC does not map neatly onto the classic benthic–limnetic axis, that high DOC favors a benthic–limnetic generalist rather than a limnetic specialist, or that the benthic–limnetic morphological dichotomy is less clear and universal than is often suggested.

A comparison of fish catch rates among local, non-local, and non-resident anglers of three northern Wisconsin lakes

Understanding influences of angler proximity on fisheries resources, in the distances anglers are willing to travel for angling opportunities and their success rates after they arrive, could influence fisheries resiliency and management applications. The Wisconsin Department of Natural Resources, Northern Highland Fishery Research Area (NHFRA), Vilas County, Wisconsin maintains a compulsory creel census that collects angler ZIP code information and species-specific angler catch rates from all visiting anglers. We used NHFRA angler ZIP code data from 2014 to 2019 on Escanaba, Nebish, and Pallette lakes to construct anglershed maps (i.e., highest density areas from which anglers traveled to fish the lakes) for muskellunge (Esox masquinongy), smallmouth bass (Micropterus dolomieu), walleye (Sander vitreus), and yellow perch (Perca flavescens) to better understand angler travel patterns. We then tested for differences in species-specific catch rates among local (from counties surrounding or adjacent to the lakes, <100-km away), non-local (from counties in southern Wisconsin, >350-km away), and non-Wisconsin resident anglers. We hypothesized that local anglers would have higher overall species-specific catch rates due to proximity to the lakes and local knowledge than non-local or non-resident anglers. Anglersheds showed high use of the lakes by non-local anglers associated with major population centers in southern Wisconsin (Dane and Milwaukee counties) and adjacent states (Illinois and Minnesota). Species-specific catch rates did not differ appreciably among local, non-local, and non-resident anglers. Our results suggest that local knowledge may not be a good indicator of fishing trip success or elevated catch rates. Technology and angler information sources may level the playing field for anglers resulting in the homogenization of catch rates. Therefore, distance from a fishery may not aid in strengthening fisheries resilience.

Female Sex Ratio Bias in Extended Growth Hatchery Walleye Fingerlings Produced in Wisconsin

AbstractSex differentiation in teleost fish is complex and often dictated by genetics, environmental conditions, and population density during critical embryonic/larval development periods. Walleye Sander vitreus have a long propagation and stocking history, and sex ratios of hatchery‐reared Walleye have been variable, typically skewed towards males, and potentially influenced by temperature. In contrast to previous fry and small fingerling Walleye stocking in Wisconsin water bodies, the Wisconsin Walleye Initiative of 2013 focused on the production of extended growth Walleye fingerlings (EGW) stocked out in fall under the assumption of greater survivorship and in response to observed declines in Walleye natural recruitment. Observed sex ratios of adult Walleye in a stocked northern Wisconsin lake chain were suggestive of EGW sex ratios skewed towards females. This lake chain has been under rehabilitation and an aggressive EGW stocking regime due to prolonged Walleye natural recruitment failures. To test whether imbalances in EGW were occurring, we collected 30 EGW from one Wisconsin hatchery in 2019 and about 50 EGW from each of three Wisconsin hatcheries in 2020 to histologically determine sex ratios. In 2019, EGW were about 97% female. In 2020, the percentage of females in hatchery samples ranged from 60% to 100%. Nonfemales in 2019 and 2020 were all undifferentiated. Our results suggest that EGW raised in Wisconsin under similar incubation and rearing protocols may be skewed towards females. If sex ratios of EGW are skewed towards females, the use of EGW may hinder efforts to rehabilitate natural recruitment. A deductive experimental and observational framework will be used to test for mechanism(s) influencing the high percentage of females in the hatchery product to inform protocols to better balance sex ratios.

Processing and Wood Factors Influence Medium Density Fiberboard Production from Young Eucalyptus grandis, E. amplifolia, Corymbia torelliana, and Cottonwood Grown in Florida USA

Fast growing Eucalyptus grandis W. Hill ex Maiden (EG), E. amplifolia Naudin (EA), Corymbia torelliana (F.Muell.) K.D.Hill &amp; L.A.S.Johnson (CT), and Populus deltoides W.Bartram ex Marshall (PD) may be deployed in Short Rotation Woody Crop (SRWC) systems in the lower Southeastern USA, especially in Florida. To evaluate these species for possible use as medium density fiberboard (MDF) and other composites, 2.5 m logs of three EG clones, three PD clones, six EA progenies, four CT trees, and one P. tremuloides Michx. (PT) tree from northern Wisconsin as a control were characterized for basic wood properties before being chipped, pulped, and pressed into MDF. The chips were thermomechanically pulped (TMP) for a two-phase study of the factors expected to influence suitability for MDF production: wood characteristics, refining system, resin system, and MDF formation. Phase I used TMP and 4% phenol-formaldehyde (PF) resin to produce 17 MDF species/genotype batches (S/GB). Thickness Swell (TS), Water Absorption (WA), Internal Bonding (IB), Modulus of Elasticity (MOE), and Modulus of Rupture (MOR) were evaluated to: (1) assess within species and within tree variation, (2) relate basic wood properties to MDF potential, and (3) examine repeatability of MDF-making. There was considerable variation among and within species, but only minor within tree variation. Six of the seventeen S/GBs had superior physical and mechanical MDF properties. In Phase II, two of the six better performing Phase I S/GBs were evaluated, along with three average Phase I S/GBs. Phase II compared the effects on IB from using tube and drum blenders for resin application, the influence of using unscreened versus screened fibers, and the differences of using PF resin at 4% or 6% versus urea-formaldehyde (UF) resin at 8% or 12%. Overall, genetic variation among species, and particularly within these species, affected their potential for commercial MDF. Log specific gravity (SG), fines, MDF SG, and fiber length influenced MDF properties, as did refining and MDF-processing variables. Further study of specific processing requirements can optimize the potential of young EG, EA, PD, and CT genotypes for MDF and other composites.

Differential defoliation and mortality of white spruce and balsam fir by eastern spruce budworm

Eastern spruce budworm (Choristoneura fumiferana) is a native defoliating insect in Canada and the United States that has large impacts on forest health. Balsam fir (Abies balsamea) and white spruce (Picea glauca) are its primary host trees, where budworm larvae consume buds and needles during larval development. While Eastern spruce budworm consumes both species, it is generally reported to defoliate balsam fir at higher levels. Investigating patterns and conditions that differentiate species’ defoliation and mortality is informative for understanding susceptibility. We studied an outbreak of spruce budworm at plantations in northern Wisconsin, USA, with defoliation first detected in 2014 that appeared to have higher impacts on white spruce, which is counter to general expectations. In 2019, we quantified spruce budworm impacts on these two tree species and tested which tree characteristics were most associated with tree defoliation and mortality. We found mortality of 60% and 49% at the sites for white spruce trees, while 0% of the balsam fir trees surveyed were dead. We determined that tree species was the main factor related to spruce budworm defoliation, rather than tree diameter at breast height or canopy class and suggest that different timing of species-specific mast-seeding events were related to defoliation and tree mortality.

Ixodes scapularis density in US temperate forests shaped by deer, earthworms, and disparate factors at two scales

AbstractForest and wildlife management can help regulate the risk of human exposure to tick‐borne pathogens by influencing the population density of host‐seeking ticks and the pathogen infection prevalence in tick populations. For the blacklegged tick (Ixodes scapularis), also known as the deer tick, the overall density of host‐seeking nymphs and the density of nymphs infected with Borrelia burgdorferi sensu stricto (which causes Lyme disease) are often closely and positively correlated. We sought to identify biotic and abiotic factors influencing nymph abundance in a multiscale assessment within and across forested landscapes in northern Wisconsin. On a set of randomly located plots within each of six mesic, hardwood‐dominated forests, we collected host‐seeking and on‐host ticks, observed two common mammal hosts (white‐tailed deer and mice), and characterized the structure and composition of the forest plant community. We also surveyed activity of exotic invasive earthworms, which are altering forest structure in the region. At the broader forest‐level scale (n = 6), nymphal tick abundance was positively related to deer population density after accounting for the negative influence of forb cover. At the finer plot‐level scale (n = 87), nymph abundance was positively correlated with the abundance of coarse woody debris and negatively correlated with the density of earthworm castings, an indicator of Lumbricid (nightcrawler) activity. Thus, we identified a suite of key factors, operating at different spatial scales, that shape the suitability of forest habitat for questing immature ticks. These findings inform our basic understanding of blacklegged tick ecology and also have important implications for managing tick‐borne pathogens in forest ecosystems and landscapes.

Mapping forest types over large areas with Landsat imagery partially affected by clouds and SLC gaps

The ecosystem services that forests provide depend on tree species composition. Therefore, it is important to map not only forest extent and its dynamics, but also composition. Open access to Landsat has resulted in considerable improvements in remote sensing methods for mapping tree species, but most approaches fail to perform when there is a shortage of clear observations. Our main goal was to map forest composition with Landsat imagery in various data availability conditions, and to investigate how the missing data, either due to clouds or scan line problems affect classification accuracy. We tested a data driven approach that is based on multi-temporal analysis of the tree species’ spectral characteristics making it applicable to regional-scale mapping even when the gap-free imagery is not available. Our study area consisted of one Landsat footprint (26/28) located in Northern Wisconsin, USA. We selected this area because of numerous tree species (23), heterogenic composition of forests where the majority of stands are mixed, and availability of high-quality reference data. We quantified how classification accuracy at the species level was affected by a) the amount of missing data due to cloud cover and Scanning Line Corrector (SLC) gaps, b) the number of acquisitions, and c) the seasonal availability of images. We applied a decision tree classifier, capable of handling missing data to both single- and a three-year Landsat-7 and Landsat-8 observations. We classified the dominant tree species in each pixel and grouped results to forest stands to match our reference data. Our results show four major findings. First, producer’s and user’s accuracies range from 46.2% to 96.2% and from 59.9% to 93.7%, respectively for the most abundant forest types in the study area (all types covering greater than 2% of the forest area). Second, all tree species were mapped with overall accuracy above 70% even in when we restricted our data set to images having gaps larger than 30% of the study area. Third, the classification accuracy improved with more acquisitions, especially when images were available for the fall, spring, and summer. Finally, producer’s accuracies for pure-stands were higher than those for mixed stands by 10 to 30 percentage points. We conclude that inclusion of Landsat imagery with missing data allows to map forest types with accuracies that previously could be achieved only for those rare years for which several gap-free images were available. The approach presented here is directly applicable to Landsat-like observations and derived products such as seasonal composites and temporal statistics that miss 30% or more of the data for any single date to develop forest composition maps that are important for both forest management and ecology.

Similar Environmental Conditions are Associated with Walleye and Yellow Perch Recruitment Success in Wisconsin Lakes

AbstractSince the mid‐2000s, recruitment of WalleyeSander vitreusin some northern Wisconsin lakes has declined, potentially because of climate‐induced changes in lake environments. Yellow PerchPerca flavescensis also an ecologically and culturally important fish species in this region, but mechanisms driving Yellow Perch recruitment are unclear because of a lack of targeted sampling. Previous studies have suggested that recruitment of these two species may be regulated by similar factors, and observed declines in Walleye recruitment may be cause for concern about Yellow Perch recruitment. Our objectives were to determine if abiotic factors related to recruitment success were similar between Walleye and Yellow Perch populations in northern Wisconsin lakes and if the probability of successful Walleye recruitment was related to estimates of juvenile Yellow Perch abundance before Walleye recruitment declines were observed. We addressed these objectives using historical data from Wisconsin lakes. Random forest analysis incorporating lake‐specific averages of predictor variables indicated that winter conditions (duration or severity), growing degree days, variation in spring temperatures, peak summer temperature, and Secchi depth were important predictors of recruitment success for both species. Logistic regression indicated that before Walleye recruitment declines were observed on some lakes (2000–2006), Walleye recruitment success was related to relative abundance of juvenile Yellow Perch in mini‐fyke‐net sampling. Our results indicate that landscape‐level patterns in recruitment success for the two species are likely similar and additional research to understand Yellow Perch recruitment trends is warranted. Better information on Yellow Perch recruitment could contribute to a better understanding of Walleye recruitment trends as declines in Yellow Perch could influence prey availability and survival of age‐0 Walleye. Furthermore, potential declines in Yellow Perch could lead to changes in the numbers and size of Yellow Perch caught by anglers, which may have implications for harvest management.

Demographic and Life History Characteristics of Black Bullheads Ameiurus melas in a North Temperate USA Lake

Black bullheads Ameiurus melas are an environmentally tolerant omnivorous fish species that are found throughout much of North America and parts of Europe. Despite their prevalence, black bullheads are an infrequently studied species making their biology, ecology, and life history poorly understood. Although limited information has been published on black bullheads, evidence suggests that bullheads can dominate the fish biomass and have profound influences on the fish community in some north temperate USA lakes. The goal of our study was to provide additional information on black bullhead population demographics, growth rates, life history characteristics, and seasonal diet preferences in a northern Wisconsin lake. Using common fish collection gears (fyke netting, electrofishing), fish aging protocols, fecundity assessments, and diet indices, our results suggested that black bullheads exhibited relatively fast growth rates, early ages at maturity, moderate fecundity, and a diverse omnivorous diet. Due to these demographic and life history characteristics, black bullheads have the potential to dominate fish community biomass in their native and introduced range. Results from our study may inform the management of black bullhead as native and invasive species.

Habitat and weather influence body condition in white‐tailed deer, Wisconsin, USA

AbstractIn temperate and northern ecosystems where there are pronounced seasonal patterns in weather and available energy, there are corresponding patterns of body condition among white‐tailed deer (Odocoileus virginianus). Body condition of white‐tailed deer can affect survival and reproduction, which has large repercussions for state‐level natural resource agencies that allocate hunting permits. In this study, we investigated how variation in winter weather, spring phenology, habitat composition, and browse quantity affected white‐tailed deer body condition across a large spatial scale. Several body condition indicators (e.g., carcass mass, heart fat, antler size) were measured by hunters for 795 deer during September–December 2016–2018 in Wisconsin, USA. Winter severity in the previous year was an unreliable predictor of fall body condition of deer when winters were considered mild or moderate. The timing of spring green‐up had a consistent effect on the body condition of all age and sex classes of deer. Earlier spring green‐up resulted in heavier fawns and larger antlers among adult males. Region and spring green‐up interacted to affect the heart fat of adult females. Earlier springs resulted in adult females in northern and central Wisconsin having a higher probability of heavy heart fat, whereas spring green‐up had no effect on adult female heart fat in southern Wisconsin. Effects of habitat differed by age and sex class of deer, and by the body condition metric being evaluated, indicating that there are important physiological differences among age and sex classes of deer that are affected by the environment. Our study demonstrates that the hunting public can contribute large‐scale, cost‐effective, and quality data to deer monitoring and research projects. It is important that natural resource agencies be able to identify and recruit highly engaged members of the hunting public to ensure project success. The timing of spring green‐up can have lasting effects on deer health that can be consistently observed the following fall, which is in contrast to the effects of winter severity that did not appear to persist when previous winters were mild or moderate. We encourage managers in northern or temperate regions to consider measures of spring green‐up timing in conjunction with traditional winter severity when making deer population management decisions, such as antlerless tag allocation.

Celebrating 75 Years of Wisconsin’s Northern Highland Fishery Research Area: The Past, Present, and Future

On June 20, 2021, the Northern Highland Fishery Research Area (NHFRA) celebrated its 75th anniversary of continuous fisheries population monitoring and compulsory angler creel census on five lakes in northern Wisconsin. In 1946, five lakes were designated as experimental fisheries research lakes and all anglers have been required to adhere to the compulsory creel census to record catch information. We review the history of the NHFRA, its role in evaluating experimental regulations, how data derived from the NHFRA were paramount in developing a critical Walleye Sander vitreus management plan for a joint tribal subsistence and recreational angling fishery, discuss the NHFRA as a training ground for early career fisheries professionals, and speculate on its future. By learning from the past and adapting to new challenges and emerging fisheries research needs, the NHFRA is poised to add to its 75‐year legacy of research and training to inform science‐based decision making and to prepare generations of new fisheries professionals. The 75‐year history of the NHFRA exemplifies the importance of adaptation, long‐term data, establishing sentinel lakes for observations of environmental change, field stations, and partnerships for successful fisheries management.

Pelagic forage versus abiotic factors as drivers of walleye growth in northern Wisconsin lakes

Pelagic forage versus abiotic factors as drivers of walleye growth in northern Wisconsin lakes

Gobbling across landscapes: Eastern wild turkey distribution and occupancy-habitat associations.

Extensive restoration and translocation efforts beginning in the mid‐20th century helped to reestablish eastern wild turkeys (Meleagris gallopavo silvestris) throughout their ancestral range. The adaptability of wild turkeys resulted in further population expansion in regions that were considered unfavorable during initial reintroductions across the northern United States. Identification and understanding of species distributions and contemporary habitat associations are important for guiding effective conservation and management strategies across different ecological landscapes. To investigate differences in wild turkey distribution across two contrasting regions, heavily forested northern Wisconsin, USA, and predominately agricultural southeast Wisconsin, we conducted 3050 gobbling call‐count surveys from March to May of 2014–2018 and used multiseason correlated‐replicate occupancy models to evaluate occupancy–habitat associations and distributions of wild turkeys in each study region. Detection probabilities varied widely and were influenced by sampling period, time of day, and wind speed. Spatial autocorrelation between successive stations was prevalent along survey routes but was stronger in our northern study area. In heavily forested northern Wisconsin, turkeys were more likely to occupy areas characterized by moderate availability of open land cover. Conversely, large agricultural fields decreased the likelihood of turkey occupancy in southeast Wisconsin, but occupancy probability increased as upland hardwood forest cover became more aggregated on the landscape. Turkeys in northern Wisconsin were more likely to occupy landscapes with less snow cover and a higher percentage of row crops planted in corn. However, we were unable to find supporting evidence in either study area that the abandonment of turkeys from survey routes was associated with snow depth or with the percentage of agricultural cover. Spatially, model‐predicted estimates of patch‐specific occupancy indicated turkey distribution was nonuniform across northern and southeast Wisconsin. Our findings demonstrated that the environmental constraints of turkey occupancy varied across the latitudinal gradient of the state with open cover, snow, and row crops being influential in the north, and agricultural areas and hardwood forest cover important in the southeast. These forces contribute to nonstationarity in wild turkey–environment relationships. Key habitat–occupancy associations identified in our results can be used to prioritize and strategically target management efforts and resources in areas that are more likely to harbor sustainable turkey populations.