Learning Ecology by Doing Ecology: Long-Term Field Experiments in Succession

Gibson, David J.; Middleton, Beth A.; Saunders, Gerald W.; Mathis, Marilyn; Weaver, Warren Thomas; Neely, Jen; Rivera, John Paolo R.; Oyler, Michelle

doi:10.2307/4450654

Cited by 14 publications

(5 citation statements)

References 9 publications

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“…While controlled experiments in greenhouses or phytotrons are helpful in elucidating mechanistic reactions and responses in plants, ecosystem‐level field manipulation studies contribute to the understanding of these responses in complex environmental networks. Naturally, both kinds of studies are needed to grasp a clearer understanding of nature (Gibson et al 1999, Wilson 2009). However, there remains a preference for laboratory and greenhouse experiments, especially in the field of ecology and forestry, due to simplified experimental setups.…”

Section: Introductionmentioning

confidence: 99%

The Kroof experiment: realization and efficacy of a recurrent drought experiment plus recovery in a beech/spruce forest

et al. 2021

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Forest ecosystems play a central role in global water and carbon cycles, yet the impact of global climate change, in particular drought, on trees and forests is poorly understood. Therefore, there is an urgent need for forest-scale experiments in improving our understanding of trees' responses to extreme drought events and subsequent recovery under field conditions. Here, we present the design and efficacy of a novel throughfall exclusion experiment with retractable roofs in a mature forest allowing for flexible drought and recovery periods. A total of 12 plots (144 AE 26 m 2 on average) with 3-7 European beech and Norway spruce trees each were established by root trenching to a depth of one meter, four years prior to the experiment. Subsequent installation of roofs (n = 6) allowed for the removal of throughfall precipitation and almost a complete non-availability of soil water in the upper 70 cm during five subsequent growing seasons, that is, 2014-2018. This reduction in available soil water resulted in pre-dawn leaf water potentials down to −1.8 MPa in mature trees. Stem diameter growth decreased by 30% in beech and 70% in spruce, and fine root abundance was reduced by 57% in beech and 73% in spruce compared with controls. After only one growing season, the mycorrhizal community composition changed in response to drought. Careful watering of hydrophobic forest soils in early summer of 2019 resulted in recovered pre-dawn leaf water potentials of drought-stressed trees within one week. Recovery of stem diameter growth, however, did not occur within the same growing season and remained reduced by 33% in beech and 69% in spruce compared with controls. The implemented throughfall exclusion system imposed recurrent seasonal drought events on a mature beech/spruce forest with high efficacy. Shifts in community composition of mycorrhizae in parallel to tree growth decline advocate for a more holistic view on forest-scale drought and watering experiments, particularly in light of more frequently predicted drought events in future. The perennial nature of mature trees and their subsequent slow recovery from drought, that is, over multiple growing seasons, argues for more long-term experiments that span several years.

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Section: Introductionmentioning

confidence: 99%

The Kroof experiment: realization and efficacy of a recurrent drought experiment plus recovery in a beech/spruce forest

et al. 2021

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“…The field was plowed in spring 1981 and mowed annually until 1987, when it was abandoned. Our experiment was initiated in early spring 1996, when the field was disked (Gibson et al 1999). Mowing and fertilizer treatments were initiated in late spring 1996.…”

Section: Site Description and Sampling Methodsmentioning

confidence: 99%

Effects of Endophyte Infection in Tall Fescue (Festuca arundinacea: Poaceae) on Community Diversity

Spyreas¹,

Gibson

Middleton

2001

International Journal of Plant Sciences

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Recent studies have suggested that the presence of endophytes in tall fescue can lead to decreased species richness in the associated plant community. To assess the generality of this hypothesis, a field study tested the effects of endophyte infection on a 3-yr-old successional field dominated by Festuca arundinacea. The potential importance of endophyte infection relative to other environmental factors was tested by including two additional treatments: the effects of soil fertility and mowing. Contrary to previous studies, a positive relationship was found between endophyte infection frequency and diversity ( ,2 N p 23 F p 5.23 R p 0.19 P ! 0.03 strong interaction was found between the mowing treatment and endophyte infection frequency in predicting diversity ( , , , ), where the maximum species richness was present in 2 N p 22 F p 36.1 R p 0.84 P ! 0.0001 plots that were both mowed and highly endophyte infected. The relationship between endophytes and diversity varied through the successional continuum (the mowing treatments) but was generally positive. The soil in mowed plots was drier than in unmowed plots ( , , ). We suggest that heavy mowing t p 2.1 df p 28 P ! 0.05 decreases soil moisture levels enough to reduce the interspecific competitive ability of infected F. arundinacea, thereby promoting local diversity. Endophyte presence is important, but the previously reported negative relationship between endophyte infection and community diversity is probably overly simplistic in complex ecological settings.

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“…The tradition of student inquiry in ecology laboratory courses is long-standing (e.g., Fail 1991, Gibson et al 1999) and has been encouraged by the dissemination of inquiry-based ecology laboratory and field exercises in publications such as Teaching Issues and Experiments in Ecology (D' Avanzo et al 2006). Although the efficacy of inquiry-based approaches to teaching in ecology laboratory and field courses might be intuitive, few studies have examined either individual exercises or entire laboratory courses in a rigorous way, as has been suggested as necessary for the improvement of ecology education (D'Avanzo 2003).…”

Section: Introductionmentioning

confidence: 99%

Inquiry‐based ecology laboratory courses improve student confidence and scientific reasoning skills

Beck

Blumer

2012

Ecosphere

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Citation: Beck, C. W., and L. S. Blumer. 2012. Inquiry-based ecology laboratory courses improve student confidence and scientific reasoning skills. Ecosphere 3(12):112. http://dx.doi.org/10.1890/ES12-00280.1Abstract. Recently, the AAAS Vision and Change report renewed the push to incorporate inquiry throughout the biology curriculum. Even prior to the report, many ecology faculty have used inquirybased approaches in their laboratory and field courses. However, the efficacy of these approaches has been assessed only to a limited degree and often at a single institution. Therefore, whether one may generalize the results of previous studies of inquiry-based teaching in laboratory courses is unclear. We examined the change in student confidence and scientific reasoning skills using published, validated instruments in inquiry-based ecology laboratory courses at two different institutions (a historically black, all-male, liberal arts college and a private research university) across multiple semesters. Students exhibited a significant increase in overall confidence and scientific reasoning skills with students in the lowest quartile at the beginning of the semester for each construct exhibiting a significantly greater gain in comparison to students in the highest quartile for the same construct. Institution had no effect on learning gains, indicating that the positive impact of inquiry-based learning is general, at least for students at our two institutions. Although weaker students exhibited greater learning gains, significant differences in confidence and scientific reasoning skills between the lowest and highest quartile persisted at the end of the semester; thus, a single, inquiry-based laboratory course is not sufficient to overcome initial differences among students. Interestingly, gains in confidence were not significantly correlated with gains in scientific reasoning with some weaker students increasing in confidence while their scientific reasoning skills decreased, which suggests that our inquiry-based laboratories did not help these students develop important metacognitive skills. Overall, our results indicate that inquiry-based laboratory courses in ecology can lead to significant learning gains, but that performance gaps among students might only be bridged by students taking multiple inquiry-based courses.

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Learning Ecology by Doing Ecology: Long-Term Field Experiments in Succession

Cited by 14 publications

References 9 publications

The Kroof experiment: realization and efficacy of a recurrent drought experiment plus recovery in a beech/spruce forest

The Kroof experiment: realization and efficacy of a recurrent drought experiment plus recovery in a beech/spruce forest

Effects of Endophyte Infection in Tall Fescue (Festuca arundinacea: Poaceae) on Community Diversity

Inquiry‐based ecology laboratory courses improve student confidence and scientific reasoning skills

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