Habitat-Specific Impacts of Multiple Consumers on Plant Population Dynamics

Multiple consumers often attack seeds, seedlings, and adult plants, but their population-level consequences remain uncertain. We examined how insect and small mammal consumers influenced the demography and abundance of the perennial shrub, bush lupine (Lupinus arboreus). In grassland and dune habitats we established replicate experimental lupine populations in 81-m2 plots that were either protected from, or exposed to, herbivorous voles and granivorous mice (via fencing) and/or root feeding insects (via insecticide treatment). Populations were initiated with transplanted seedlings in 1999 and 2000. We followed the demography of these cohorts, subsequent generations, and the seed bank for 5.5 years. Voles and insects killed many seedlings in dune (1999 only) and grassland (1999 and 2000) habitats. After 2000, insects and voles had minimal effects on seedling or adult survival. Seed predation by granivorous mice, however, greatly depressed seedling recruitment, resulting in lower adult lupine abundance in control plots vs. those protected from rodents. In grasslands, initial effects of voles and insects on seedling survival produced large differences among treatments in adult plant density and the cumulative number of seeds produced throughout the experiment. Differences among grassland populations in seed rain, however, had little influence on the magnitude of seedling recruitment into this habitat. Instead, recruitment out of a preexisting seed bank compensated for the lack of seed production in populations exposed to consumers. Shading by dense adults in plots protected from consumers limited seedling establishment within these populations. Although differences among populations in cumulative seed rain did not influence adult establishment, populations protected from consumers accumulated substantially larger seed banks than controls. These results illustrate how density dependence, habitat-specific seed dynamics, and particular demographic impacts of consumers interact to shape plant population responses to consumers

Consumers Limit the Abundance and Dynamics of a Perennial Shrub with a Seed Bank

For nearly 30 years, ecologists have argued that predators of seeds and seedlings seldom have population-level effects on plants with persistent seed banks and density-dependent seedling survival. We parameterized stage-based population models that incorporated density dependence and seed dormancy with data from a 5.5-year experiment that quantified how granivorous mice and herbivorous voles influence bush lupine (Lupinus arboreus) demography. We asked how seed dormancy and density-dependent seedling survival mediate the impacts of these consumers in dune and grassland habitats. In dune habitat, mice reduced analytical lambda (the intrinsic rate of population growth) by 39%, the equilibrium number of above-ground plants by 90%, and the seed bank by 98%; voles had minimal effects. In adjacent grasslands, mice had minimal effects, but seedling herbivory by voles reduced analytical lambda by 15% and reduced both the equilibrium number of aboveground plants and dormant seeds by 63%. A bootstrap analysis demonstrated that these consumer effects were robust to parameter uncertainty. Our results demonstrate that the quantitative strengths of seed dormancy and density-dependent seedling survival-not their mere existence-critically mediate consumer effects. This study suggests that plant population dynamics and distribution may be more strongly influenced by consumers of seeds and seedlings than is currently recognized

Relationship of Climate and Growth of Quaking Aspen (Populus Tremuloides) in Yellowstone National Park

Quaking aspen is a widespread tree that is in decline across wide areas of western North America, and is predicted to experience a large range shift if future climate predictions are realized. The purpose of our study was to determine what climate factors have influenced aspen growth in Yellowstone National Park, USA, and to determine whether these climatic influences vary across a heterogeneous landscape. We extracted increment cores from 10-12 aspen in each of 16 stands spread across a 1,526 km2 area. Using ring widths, we created a182-year standardized chronology from 1821 to 2003 A.D. composed of 151 series. We then assessed correlations of growth using instrumental records of temperature, precipitation, and the Palmer Drought Severity Index (PDSI) from 1932 to 2002, and records of maximum snow depth from 1949 to 2002. We found positive relationships between growth and springtime maximum snow depth, and negative relationships between growth and temperature and moisture stress (PDSI). Aspen were impacted by these factors from the previous growing season, suggesting a lag effect of climate. Variation in sensitivity to temperature and PDSI among our stands could not be explained by landscape variables, but sensitivity to the prior March maximum snow depth was greater at high elevations and on shallower slopes. High snow depth probably produces a long- lived water source at the beginning of the growing season. Our study demonstrates that aspen respond to variation in moisture related factors, and that changes in aspen growth due to future climate shifts will vary across small scales

Industrial Energy Development Decouples Ungulate Migration from the Green Wave

The ability to freely move across the landscape to track the emergence of nutritious spring green-up (termed ‘green-wave surfing’) is key to the foraging strategy of migratory ungulates. Across the vast landscapes traversed by many migratory herds, habitats are being altered by development with unknown consequences for surfing. Using a unique long-term tracking dataset, we found that when energy development occurs within mule deer (Odocoileus hemionus) migration corridors, migrating animals become decoupled from the green wave. During the early phases of a coalbed natural gas development, deer synchronized their movements with peak green-up. But faced with increasing disturbance as development expanded, deer altered their movements by holding up at the edge of the gas field and letting the green wave pass them by. Development often modified only a small portion of the migration corridor but had far-reaching effects on behaviour before and after migrating deer encountered it, thus reducing surfing along the entire route by 38.65% over the 14-year study period. Our study suggests that industrial development within migratory corridors can change the behaviour of migrating ungulates and diminish the benefits of migration. Such disruptions to migratory behaviour present a common mechanism whereby corridors become unprofitable and could ultimately be lost on highly developed landscapes

A Comparison of Wolf Depredation Sites in Areas With Migratory and Resident Elk

As large carnivores recover in many wilderness areas and mixed-use landscapes, wildlife management agencies must seek ways to minimize private property damage while maintaining viable populations. Although much is known about carnivore-livestock conflicts, drivers of these processes in the Northern Rocky Mountains are still emerging amid the dynamic conditions of recovering predator populations (gray wolves [Canis lupus] and grizzly bears [Ursus arctos horribilis]), declining elk productivity, and the re-distribution of migratory and resident elk subpopulations. There has been little research to date that examines the influence of fine-scale elk distribution and movements on patterns of livestock depredation. In this study, we analyze four years of cattle depredation data, two years of summer and fall wolf predation data (n = 4 wolves), and three years of elk movement data (n= 86 elk) to assess the influence of migratory and resident prey on the location and occurrence of wolf depredations on cattle. Wolves living in migratory elk areas face low densities of their preferred prey in summer, when elk depart for higher elevations inside Yellowstone National Park (YNP), while wolves living in the resident elk area have access to abundant elk year round. Wolves living in both areas have the potential to interact with several thousand head of cattle. We used logistic regression to compare the relative influence of landscape features on the risk of livestock depredation in the migratory and resident elk areas. Locations of wolf-killed cattle showed differences between the migratory elk area and the resident elk area. Depredation sites in the resident elk area were associated with habitats closer to roads and with high elk density, while depredation sites in the migratory elk area were associated with dens, streams, and open habitat away from the forest edge. Our findings indicate that knowledge of ungulate distributions and migration patterns can help understand and predict hotspots of wolf conflict with livestock

NUTRITONAL CONDITION OF ADULT FEMALE SHIRAS MOOSE IN NORTHWEST WYOMING

The "animal indicator concept" assumes that because an animal is a product of its en­vironment, it likely reflects the quality of its environment. Although this concept has been applied to assess population condition and habitat quality for Alaskan moose (Alces alces gigas), to our knowledge this is the first time it has been used to assess the nutritional status of a Shiras moose (A.a. shirasi) population. We investigated the physical condition and nutritional status of adult (≥ 2 years) female Shiras moose captured in northwest Wyoming during the winters of 2005-2007. Rump fat depth was measured via ultrasonography and biological samples were collected and analyzed for hematology, serum chemistry, micro- and macronutrients, endo- and ectoparasites, and bacterial and viral serology. Five blood parameters believed to be important predictors of moose condition (packed cell volume, total serum protein, hemoglobin [Hb], calcium [Ca], and phosphorous [P]) were compared to data from Alaskan moose considered to be in average-above average condition. Micro- and macronutrient values were evaluated based on published deficiency levels for domestic herbivores. We conducted a correlation analysis to determine if a significant relationship existed between hematological and serum chemical parameters and rump fat depth. Mean rump fat depth did not differ among years and was greater than reported values for Alaskan moose. However, a high proportion of sampled moose had Hb, Ca, and P values lower than Alaskan moose that were considered to be in average condition. Hair and serum micro- and macronutrient analyses indicated a high proportion of moose were potentially deficient in copper, zinc, manganese, and P. We observed a marginally significant relationship between depth of rump fat and two serum chemical parameters (aspartate amimotransferase and lactate dehydrogenase). The results are suggestive of a Shiras moose population in marginal physical condition that is probably related to less than optimal habitat quality. These findings should assist managers in evaluating the health of Shiras moose populations throughout their range

Health, Nutrition and Healthcare Availability (Survey 2, Report 2)

With support and collaboration from the W.K. Kellogg Foundation through the America Healing initiative, researchers at the University of Michigan are leading the National Voices Project (NVP) from 2011-2015. The central goals of the NVP are to examine the sources of racial/ethnic inequity and other disparities for children in the United States today, identify interventions that address disparities effectively, and inform the public dialogue about racial healing and racial equality. The NVP offers a fresh perspective on community-level opportunities for children throughout the country, in the domains of health and nutrition, education, and economic security -- through the eyes of adults whose work and volunteer efforts affect such opportunities. In other words, the NVP reflects the perceptions of individuals throughout the United States who are in a position to improve children's opportunities in the future. The questionnaire for NVP Survey 2 was developed by the National Voices Project team at the University of Michigan, with input from WKKF collaborators. We examined how individuals who work or volunteer with children view opportunities for education, health and healthcare, and economic well-being related to children and adolescents. Many of the questions were identical to questions fielded for NVP Survey 1 in 2011, to facilitate comparisons of responses across these different samples and over time. New questions in NVP Survey 2 centered on respondents' perceptions of segregation and inequities in the communities they know best, and on respondents' awareness about efforts to bridge racial/ethnic inequities in those communities

Education and Learning Opportunities (NVP 2014, Report 3)

With support and collaboration from the W.K. Kellogg Foundation through the America Healing initiative,  researchers at the University of Michigan are leading the National Voices Project (NVP) from 2011-2016. The central goals of the NVP are to examine the sourcesof racial/ethnic inequity and other disparitiesfor children in the United States today and identify interventions that address disparities effectively.The NVP offers an unprecedented perspective on community-level opportunities for children throughout the country, in the domains of health and nutrition, education and learning, and economic security – through the eyes of adults whose occupations and volunteer work affect such opportunities. In other words, the NVP reflects the perceptions of individuals throughout the United States who are in a position to improve children's opportunities inthe future. We generally use the word "children" throughout the report to describe children from age 0-18 years, unless otherwise noted.Previous reports for NVP 2014 focused chiefly on respondent characteristics and findings regarding health,  healthcare, and nutrition. This report for NVP 2014 will center on findings related to children's education and learning

Opportunities and Barriers Related to Income (Survey 2, Report 4)

Led by researchers at the University of Michigan, the National Voices Project is an effort to bring the perspectives of thousands of people in communities across the United States to the national dialogue about opportunities and barriers for children related to race/ethnicity. The National Voices Project conducts major national surveys twice each yearamong adults who work and volunteer on behalf of children. These surveys focus on racial/ethnic disparities at the community level that affect children?s health, education, and economic security.NVP Survey 1 was conducted in November-December 2011. NVP Survey 2 was fielded in August-September 2012.The final eligible sample for NVP Survey 2 included 2,311 adults from 48 states and D.C. NVP Survey 2 differed from NVP Survey 1 in two key respects: 1) NVP Survey 2 included an oversample in communities included in the "Place Matters" initiative led by the Joint Center for Political and Economic Studies, a fellow grantee of the W.K. Kellogg Foundation. The oversample included sufficient numbers of responses to permit the NVP team to analyze differences across 6 specific "Place Matters" counties, and 2) Questions were asked in greater depth about efforts at community levels about bridging efforts to address racial/ethnic inequities.