Background Continuous calls for reform in science education emphasize the need to provide science experiences in lower-division courses to improve the retention of STEM majors and to develop science literacy and STEM skills for all students. Open or authentic inquiry and undergraduate research are effective science experiences leading to multiple gains in student learning and development. Most inquiry-based learning activities, however, are implemented in laboratory classes and the majority of them are guided inquiries. Although course-based undergraduate research experiences have significantly expanded the reach of the traditional apprentice approach, it is still challenging to provide research experiences to nonmajors and in large introductory courses. We examined student learning through a web-based authentic inquiry project implemented in a high-enrollment introductory ecology course for over a decade. Results Results from 10 years of student self-assessment of learning showed that the authentic inquiry experiences were consistently associated with significant gains in self-perception of interest and understanding and skills of the scientific process for all students—both majors and nonmajors, both lower- and upper-division students, both women and men, and both URM and non-URM students. Student performance in evaluating the quality of an inquiry report, before and after the inquiry project, also showed significant learning gains for all students. The authentic inquiry experiences proved highly effective for lower-division students, nonmajors, and women and URM students, whose learning gains were similar to or greater than those of their counterparts. The authentic inquiry experiences were particularly helpful to students who were less prepared with regard to the ability to evaluate a scientific report and narrowed the performance gap. Conclusions These findings suggest that authentic inquiry experiences can serve as an effective approach for engaging students in high-enrollment, introductory science courses. They can facilitate development of science literacy and STEM skills of all students, skills that are critical to students’ personal and professional success and to informed engagement in civic life.

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Introduction: A fundamental challenge to the integrity of tropical dry forest ecosystems is the invasion of nonnative grass species. These grasses compete for resources and fuel anthropogenic wildfires. In 2012, a bulldozer from the Puerto Rico Electric Power Authority cleared a 570-m trail from a state road into a mature dry forest section of Guánica Forest to control a wildfire. We monitored colonization by a non-native invasive grass (Megathyrsus maximus), a highly invasive tree (Leucaena leucocephala), and a native grass (Uniola virgata), as well as natural regeneration, along the bulldozer trail. We determined whether bulldozing facilitated colonization by these species into the forest and the extent of spread. Results: Distance from propagule source and temporal variations strongly influenced colonization by our three focal species. Megathyrsus maximus invaded along the trail from source populations by the state road. The establishment of new colonies of M. maximus seedlings went as far as 570 m inside the forest (i.e., at the end of the bulldozer trail), but we found most new colonies within 270 m of the road. Leucaena leucocephala exhibited a similar spreading pattern. Before disturbance, Uniola virgata was distributed widely across the forest, but the highest densities were found in areas near the latter portion (> 401 m) of the bulldozer trail. Subsequently, the species formed new clumps along more than half of the trail (250 to 570 m), apparently colonizing from undisturbed patches nearby. Conclusions: Bulldozing facilitated the invasion of non-native vegetation. The projected community assemblage will be more fire-prone than before since M. maximus carries fire across the landscape better than U. virgata, emphasizing the capacity of invasive plant colonization to alter local ecological processes after only a single wildfire and bulldoze event. Our results provide a valuable baseline for short-term vegetation response to anthropogenic disturbances in tropical semi-deciduous dry forests.

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