Competition has been widely assumed to be one of the principal mechanisms underlying the resistance of shrub and herbaceous communities to invasion by trees. However, there are potential mechanisms by which low-growing species, particularly in physically stressful sites, could enhance growth or survival of tree seedlings (facilitation). The balance of inhibition and facilitation will determine the net effects of a community on tree seedling growth and survival. We conducted a large-scale field experiment to quantify the net effects of four major physiognomic types (shrub thickets, shrubby grass meadows, grass meadows, and herbaceous meadows) commonly found both in old fields and along utility rights-of-way on the growth and survival of three common tree species: sugar maple (Acer saccharum), red maple (Acer rubrum), and gray birch (Betula populifolia). The eight community types were distributed in 23 sites representative of the range of upland environments present in the Hudson Valley of New York. Growth of planted seedlings of all three tree species was uniformly slow in all of the community types and environments. In all cases, the net effect of intact vegetation was to inhibit the growth of the tree seedlings. The intensity of competition varied substantially among the 23 sites but was not consistently related either to community type or to the biomass of the intact community. Instead, variation in the intensity of competition was related to the underlying favorability of the site for the growth of a particular target tree species. On physically unfavorable sites, tree seedlings grew slowly because of physical stress rather than competition with the intact vegetation. As site quality increased, the intensity of competition increased. Thus, competition and physical stress traded off along a site-quality gradient, with the result that tree seedling growth was uniformly slow. In contrast to the results for growth, there were cases in which the survival of these young tree seedlings was enhanced (facilitated) by the presence of intact vegetation. In particular, survival of the highly shade tolerant but drought intolerant sugar maple seedlings was facilitated by intact vegetation at many sites, especially for the 1988 cohort, which experienced a drought during its first growing season. Since we detected no consistent differences among communities in the intensity of competitive effects on seedling growth, the apparent differences among early successional communities in resistance to tree seedling establishment may be caused by variation in the duration of competition resulting from differences in height and canopy structure of the low-growing communities.

The level of ecological literacy among the general population in the US and other countries is not known, although there is widespread concern that it is too low to enable effective social responses to current problems. Here, we describe a framework for conceptualizing ecological literacy. This framework combines ideas and approaches from the social sciences with content deemed critical by ecology professionals. We conclude with key contentions and questions that should initiate a dialogue aimed at improving ecological literacy among the public. As ecological literacy was the theme of the 93rd Annual Meeting of the Ecological Society of America in 2008, we believe it is time for this discussion to be expanded, increased in priority, and brought to fruition.

Field experiences can provide transformative opportunities for many individuals who eventually pursue ecology, natural resource, and conservation careers. However, some of the same elements of field-based programs that define and provide pivotal experiences for some represent barriers for others, especially students from underrepresented groups. Barriers may be financial, physical, cultural, or social. Issues of gender, identity, and race/ethnicity, for example, can be isolating or shut down learning during intensive field experiences when group leaders are not prepared to respond to interpersonal challenges. We explore some benefits and barriers presented by field learning UNDERGRADUATE EDUCATION

We examined the effects of separate removal experiments of two generalist consumers, the white-footed mouse (Peromyscus leucopus) and the eastern chipmunk (Tamias striatus), on nest predation rates of forest songbirds. Mice are numerically dominant at our study sites and were shown to be strong predators in other predator-prey interactions, such as those involving gypsy moths. Therefore, we hypothesized that removal of mice would result in decreased levels of nest predation relative to control treatments with a complete predator assemblage, but that the removal of chipmunks would not result in decreased nest predation. Both hypotheses were supported. Mice depredated Ͼ60% of artificial nests in control plots (mouse populations intact), whereas chipmunks depredated ϳ20%. Daily nest mortality rates in mouse removal treatments were less than half the rates in controls but were virtually identical between chipmunk removal and control treatments. Nonetheless, when we examined predation rates across plots in which the density of mice varied naturally, total daily mortality rates declined as the density of mice increased. This pattern occurred because mortality from non-mouse predators decreased as the density of mice increased and overwhelmed increasing mortality from mice to drive the overall dynamics of the system. Analysis of the relationships between the density of mice and predation rates by mice as a function of the abundance of natural food in their environment revealed probable reasons for these conflicting results. We suggest that high local densities of mice deplete resources for larger, non-mouse predators, which preferentially occupy areas of few mice and high local food abundance. In these areas, songbirds may be faced with higher overall nest predation dominated by non-mouse predators. Mice thus influence nest predation rates through both direct and indirect pathways.

Improving ecological education through a four-dimensional frameworkA t its November 2018 meeting, the ESA's Governing Board made the important decision to endorse the 4-Dimensional Ecology Education (4DEE) framework. Developed over the past 3 years by a task force of ESA members who solicited input from a variety of groups, the framework takes a fresh and innovative approach toward the teaching of ecology.Early on, the task force recognized that a simple listing of concepts would neither fully address ESA member needs for fostering excellence in ecology education, nor capture the way that ecology has matured as a diverse, multidisciplinary science. Development of the 4DEE framework was informed by other initiatives such as AAAS's Vision and Change in Undergraduate Biology Education (https://bit.ly/2sPupbX) and the Next Generation Science Standards (www.nextgenscience.org). Those approaches are also explicitly multidimensional, but we believe they do not go far enough to fully inform ecology educators. Instead, the 4DEE framework (www.esa.org/4DEE) involves four dimensions that educators should incorporate when teaching ecology: Core Ecological Concepts (the familiar hierarchy of ecology, from the individual to the biosphere), Ecology Practices (relevant skills that students should have), Human-Environment Interactions (ways that humans and nature affect each other), and Cross-cutting Themes (topics like scale and evolution). Some may ask: "What's new here?" We contend that 4DEE is innovative for several reasons. First, with its distinctive emphasis on human-environment interactions, on practices like the natural history approach and field-based ways of doing science, and on the prominence of cross-cutting themes like spatial/temporal scale and disturbance, a multidimensional approach is far superior to the traditional one-dimensional approach to teaching ecology. The inclusion of multiple dimensions beyond just Core Ecological Concepts allows integration of various ways of thinking and doing ecology with teaching big ideas (eg population processes, community theory, transfer of nutrients and energy in ecosystems) in the discipline.Second, the 4DEE framework elevates the Human-Environment dimension so that it is integrated with the teaching of the Core Ecology Concepts and not just included as an addendum to a course. Increasing emphasis on human dependency on the environment, ecosystem management, and related ideas will highlight the relevance of ecological knowledge to human welfare. By enhancing our ability to communicate ecology broadly, the framework aids in developing policies and practices that address current global environmental problems, especially those affecting otherwise disenfranchised groups.Third, we expect a tremendous amount of innovation will emerge from the community of ecology educators as they use, modify, and extend 4DEE in research and practice. Their creative and critical research-based work will explore how to realize and assess multi-dimensional teaching at different scales (eg a single ...