Housing growth,forests, and public lands in Northern Wisconsin from 1940 to 2000

Rural, forested areas throughout the United States are experiencing strong housing growth with potentially detrimental impacts on the environment. In this paper, we quantify housing growth in Northern Wisconsin over the last sixty years to determine if growth rates were higher near public lands, which may represent an important recreational amenity. We used data from the U.S. Census to produce decadal housing density estimates, “backcasts,” from 1940 to 2000 for northern Wisconsin to examine “rural sprawl” in northern Wisconsin and its relationship to forested areas and public lands. We integrated housing density estimates with the 1992/1993 National Land Cover Dataset to examine the relationship between rural sprawl and land cover, especially forests. Between 1940 and 2000, private land with <2 housing units/km² decreased from 47% to 21% of the total landscape. Most importantly, housing growth was concentrated along the boundaries of public lands. In 14 of the 19 counties that we studied, housing growth rates within 1 km of a public land boundary exceeded growth rates in the remainder of the county, and three of the five counties that did not exhibit this pattern, were the ones with the least amount of public land. Future growth can be expected in areas with abundant natural amenities, highlighting the critical need for additional research and effective natural resource management and regional planning to address these challenges.     

Manure composition and incorporation effects on phosphorus in runoff following corn biomass removal

Greater demand for corn ( L.) stover for bioenergy use may lead to increased corn production acreage with minimal surface residue cover, resulting in greater risk for soil erosion and phosphorus (P) losses in runoff. A rainfall simulation study was conducted to determine the effects of spring-applied dairy cow () manure (none, in-barn composted, and exterior walled-enclosure pit) with >200 g kg organic solids content following fall corn biomass removal with and without incorporation (chisel plow [CP] and no-till [NT]) on sediment and P in runoff. Runoff was collected from a 0.83-m area for 60 min following the onset of rainfall simulation (76 mm h), once in spring and once in fall. Runoff dissolved reactive P (DRP) and dissolved organic P (DOP) concentrations were positively correlated with manure P rate and were higher in NT compared with CP. Conversely, sediment and particulate P (PP) concentrations in runoff were inversely correlated with manure P rate (and manure solids) and were higher in CP compared with NT. Runoff volume where no manure was applied was higher in NT than in CP in spring but similar in fall. The addition of manure reduced runoff volumes by an average of 82% in NT and 42% in CP over spring and fall. Results from this study indicate that surface application of dairy manure with relatively high solids content may reduce sediment and PP losses in runoff without increasing the risk of increased DRP and DOP losses in the year of application where corn biomass is harvested.     

Developing a Monitoring Protocol for Visitor-Created Informal Trails in Yosemite National Park,USA

Informal trails created or perpetuated by visitors is a management challenge in many protected natural areas such as Yosemite National Park. This is a significant issue as informal trail networks penetrate and proliferate into protected landscapes and habitats, threatening ecological integrity, aesthetics, and visitor experiences. In order to develop effective strategies for addressing this problem under an adaptive management framework, indicators must be developed and monitoring protocol must be established to gather timely and relevant data about the condition, extent, and distribution of these undesired trail segments. This article illustrates a process of developing and evaluating informal trail indicators for meadows in Yosemite Valley. Indicator measures developed in past research were reviewed to identify their appropriateness for the current application. Information gaps in existing indicator measures were addressed by creating two new indices to quantify the degree of informal trailing based on its land fragmentation effects. The selected indicator measures were applied to monitoring data collected between 2006 and 2008. The selected measures and indices were evaluated for their ability to characterize informal trail impacts at site and landscape scales. Results demonstrate the utility of indicator measures in capturing different characteristics of the informal trail problem, though several metrics are strongly related to each other. The two fragmentation indices were able to depict fragmentation without being too sensitive to changes in one constituent parameter. This study points to the need for a multiparameter approach to informal trail monitoring and integration with other monitoring data. Implications for monitoring programs and research are discussed.     

Do Energy‐Based PET Models Require More Input Data than Temperature‐Based Models? — An Evaluation at Four Humid FluxNet Sites

It is well established that wet environment potential evapotranspiration (PET) can be reliably estimated using the energy budget at the canopy or land surface. However, in most cases the necessary radiation measurements are not available and, thus, empirical temperature‐based PET models are still widely used, especially in watershed models. Here we question the presumption that empirical PET models require fewer input data than more physically based models. Specifically, we test whether the energy‐budget‐based Priestley‐Taylor (P‐T) model can reliably predict daily PET using primarily air temperature to estimate the radiation fluxes and associated parameters. This method of calculating PET requires only daily minimum and maximum temperature, day of the year, and latitude. We compared PET estimates using directly measured radiation fluxes to PET calculated from temperature‐based radiation estimates at four humid AmeriFlux sites. We found good agreement between P‐T PET calculated from measured radiation fluxes and P‐T PET determined via air temperature. In addition, in three of the four sites, the temperature‐based radiation approximations had a stronger correlation with measured evapotranspiration (ET) during periods of maximal ET than fully empirical Hargreaves, Hamon and Oudin methods. Of the three fully empirical models, the Hargreaves performed the best. Overall, the results suggest that daily PET estimates can be made using a physically based approach even when radiation measurements are unavailable.     

Fish Mercury and Surface Water Sulfate Relationships in the Everglades Protection Area

Few published studies present data on relationships between fish mercury and surface or pore water sulfate concentrations, particularly on an ecosystem-wide basis. Resource managers can use these relationships to identify the sulfate conditions that contain fish with health-concerning total mercury (THg) levels and to evaluate the role of sulfate in methyl-mercury (MeHg) production. In this study, we derived relationships between THg in three fish trophic levels (mosquitofish, sunfish, and age-1 largemouth bass) and surface water sulfate from 1998 to 2009 for multiple stations across the Everglades Protection Area (EPA). Results show the relationship between sulfate and fish THg in each fish type is nonlinear and largely skewed, similar to the relationship between MeHg production and sulfate concentration in peatland sediment pore water identified by other researchers. Peak fish THg levels occurred in ~1 to 12 mg/L sulfate conditions. There was significant variability in the fish THg data, and there were several instances of high-fish THg levels in high-sulfate conditions (>30 mg/L). Health-concerning fish THg levels were present in all surface water sulfate conditions; however, most of these levels occurred in 1–20 mg/L sulfate. The data in this study, including recent studies, show consistent and identifiable areas of high- and low-fish THg across the spectrum of surface water sulfate concentration, therefore, applying an ecosystem-wide sulfur strategy may be an effective management approach as it would significantly reduce MeHg risk in the EPA.     

Relationships between phosphorus levels in soil and in runoff from corn production systems

Phosphorus-enriched runoff from cropland can hasten eutrophication of surface waters. A soil P level exceeding crop needs due to long-term fertilizer and/or manure applications is one of several potential sources of increased P losses in runoff from agricultural systems. Field experiments were conducted at locations representative of three major soil regions in Wisconsin in corn (Zea mays L.) production systems to determine the effect of tillage, recent manure additions, soil P extraction method, and soil sampling depth (0-2, 0-5, and 0-15 cm) on the relationship between soil test P level and P concentrations in runoff. Runoff from simulated rainfall (75 mm h(-1)) was collected from 0.83-m2 areas for 1 h after rainfall initiation and analyzed for dissolved phosphorus (DP), total phosphorus (TP), and sediment. The DP fraction of the TP concentration in runoff ranged from 5 to 17% among sites with most of the variation in TP due to varying sediment concentration on the well-drained silt loam soils and to soil test P level on the poorly drained silty clay loam soil. In 213 observations across a range of soils and managements, good relationships occurred between soil test P level and DP concentration in runoff for most of the tests and sampling depths used. Recent manure additions and high levels of surface cover from corn residue sometimes masked this relationship. The slope of DP relative to soil test P level was markedly higher on the silty clay loam soil than on the silt loam soils possibly due to soil permeability-infiltration rate differences. Agronomic soil P tests were as effective as environmentally oriented soil P tests for predicting DP concentrations in runoff.     

Identifying hydrologically sensitive areas: bridging the gap between science and application

Researchers have noted that current water quality protection strategies, like nutrient management plans, lack a sound hydrological underpinning for pollutant transport processes. This is especially true for areas like the northeastern U.S. where copious research has shown that variable source area hydrology largely governs runoff generation. The goal of this study was to develop a scientifically justified method to identify the locations that generate overland flow. Furthermore, this methodology must be computationally simple enough that it can be utilized or incorporated into nutrient management plans and other established water quality tools. We specifically tested the reliability of the 'distance from a stream,'D(s), and the 'topographic index,'lambda, to predict areas with a high propensity for generating overland flow, i.e. hydrologically sensitive areas (HSA). HSAs were defined by their probability of generating runoff, P(sat), based on 30 year simulations using a physically based hydrological model. Using GIS, each location's P(sat) was correlated with D(s) and lambda. We used three Delaware Co., NY watersheds in the New York City watershed system with areas varying in size from 1.6 to 37 km2 and with forested and agricultural land uses. The topographic index gave stronger, more regionally consistent correlations with P(sat) than did D(s). Equations correlating lambda and P(sat) for each month are presented and can be used to estimate hydrological sensitivity in the region surrounding our study watersheds, i.e. in Delaware Co. This work is currently being incorporated into an Internet Mapping System to facilitate user-friendly, on-line identification of HSAs.