Understanding the mechanisms that promote the coexistence of hundreds of species over small areas in tropical forest remains a challenge. Many tropical tree species are presumed to be functionally equivalent shade tolerant species but exist on a continuum of performance trade‐offs between survival in shade and the ability to quickly grow in sunlight. These trade‐offs can promote coexistence by reducing fitness differences. Variation in plant functional traits related to resource acquisition is thought to predict variation in performance among species, perhaps explaining community assembly across habitats with gradients in resource availability. Many studies have found low predictive power, however, when linking trait measurements to species demographic rates. Seedlings face different challenges recruiting on the forest floor and may exhibit different traits and/or performance trade‐offs than older individuals face in the eventual adult niche. Seed mass is the typical proxy for seedling success, but species also differ in cotyledon strategy (reserve vs. photosynthetic) or other leaf, stem and root traits. These can cause species with the same average seed mass to have divergent performance in the same habitat. We combined long‐term studies of seedling dynamics with functional trait data collected at a standard life‐history stage in three diverse neotropical forests to ask whether variation in coordinated suites of traits predicts variation among species in demographic performance. Across hundreds of species in Ecuador, Panama and Puerto Rico, we found seedlings displayed correlated suites of leaf, stem, and root traits, which strongly correlated with seed mass and cotyledon strategy. Variation among species in seedling functional traits, seed mass, and cotyledon strategy were strong predictors of trade‐offs in seedling growth and survival. These results underscore the importance of matching the ontogenetic stage of the trait measurement to the stage of demographic dynamics. Our findings highlight the importance of cotyledon strategy in addition to seed mass as a key component of seed and seedling biology in tropical forests because of the contribution of carbon reserves in storage cotyledons to reducing mortality rates and explaining the growth‐survival trade‐off among species.
Performance/security trade-off is widely noticed in CFI research, however, we observe that not every CFI scheme is subject to the trade-off. Motivated by the key observation, we ask three questions: ➊ does trade-off really exist in different CFI schemes? ➋ if trade-off do exist, how do previous works comply with it? ➌ how can it inspire future research? Although the three questions probably cannot be directly answered, they are inspiring. We find that a deeper understanding of the nature of the trade-off will help answer the three questions. Accordingly, we proposed the
- NSF-PAR ID:
- 10307270
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Cybersecurity
- Volume:
- 4
- Issue:
- 1
- ISSN:
- 2523-3246
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Synthesis : With strikingly consistent patterns across three tropical forests, we find strong evidence for the promise of functional traits to provide mechanistic links between seedling form and demographic performance. -
This fundamental research in pre-college education engineering study investigates the ways in which elementary school students and their teacher balance the tradeoffs in engineering design. STEM education reforms promote the engagement of K-12 students in the epistemic practices of disciplinary experts to teach content.1,2,3 This emphasis on practices is a paradigm shift that requires both extensive professional development and research to learn about the ways in which students and teacher learn about and participate in these practices. Balancing tradeoffs is an important practice in engineering but most often in classroom curricula it is embedded in the concept of iteration1,4; however, improving a design is not always the same as balancing trade-offs.1 Optimizing a multivariate problem requires students to engage in a number of engineering practices, like considering multiple solution, making tradeoffs between criteria and constraints, applying math and science knowledge to problem solving, constructing models, making evidence-based decisions, and assessing the implications of solutions5. The ways in which teachers and students collectively balance these tradeoffs in a design has been understudied1. Our primary research questions are, “How do teachers and students make decisions about making tradeoffs between criteria and constraints” and “How do experiences in teacher workshops affect the ways they implement engineering projects in their classes.” We take an ethnographic perspective to investigate these phenomena, and collected video data, field notes, student journals, and semi-structured interviews of eight elementary teachers in a workshop and similar data from two of the workshop teachers’ classes as they implemented the curriculum they learned in the workshop. Our analyses focus on the disciplinary practices teachers and students use to make decisions for balancing tradeoffs, how they are supported (or impeded) by teachers, and how they justify these decisions. Similarly, we compared two of the teachers wearing their “student hat” in the workshop as well as their “teacher hat” in the classroom5. Our analyses suggest three significant findings. First, teachers and students tended to focus on one criterion (e.g. cost, performance) and had few discussions about trying to minimize cost and maximize performance. Second, curriculum design significantly impacts the choices students make. Using two examples, we will show the impact of weighting criteria differently on the design strategies teachers and students make. Last, we noted most of the feedback given was related to managing classroom activity rather than supporting students’ designs. Implications of this study are relevant to both engineering educators and engineering curriculum developers.more » « less
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Abstract Epiphytes are characterized by their ability to survive without a root connection to the ground, but many basic life‐history traits and ecological trade‐offs of this unique aerial growth habit remain largely uncharacterized. Mortality causes are still not well understood, but falling from the host tree has been suggested as a leading cause of epiphyte mortality and community dynamics. Little empirical evidence exists for
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Synthesis . Plants that are adapted for the canopy experience a trade‐off with higher mortality when in contact with terrestrial soil. Follow‐up studies should explore the role of terrestrial soil microbes and physiological constraints as potential drivers of decreased grounded epiphyte survival. -
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