A Scientist's Guide to Achieving Broader Impacts through K-12 STEM Collaboration.

The National Science Foundation and other funding agencies are increasingly requiring broader impacts in grant applications to encourage US scientists to contribute to science education and society. Concurrently, national science education standards are using more inquiry-based learning (IBL) to increase students' capacity for abstract, conceptual thinking applicable to real-world problems. Scientists are particularly well suited to engage in broader impacts via science inquiry outreach, because scientific research is inherently an inquiry-based process. We provide a practical guide to help scientists overcome obstacles that inhibit their engagement in K-12 IBL outreach and to attain the accrued benefits. Strategies to overcome these challenges include scaling outreach projects to the time available, building collaborations in which scientists' research overlaps with curriculum, employing backward planning to target specific learning objectives, encouraging scientists to share their passion, as well as their expertise with students, and transforming institutional incentives to support scientists engaging in educational outreach.

DIVERSITY ENHANCES COVER AND STABILITY OF SEAWEED ASSEMBLAGES: THE ROLE OF HETEROGENEITY AND TIME.

Generalizations regarding the mechanisms underlying the effects of plant diversity on ecosystem processes, and whether the patterns transcend study systems remain elusive. Many terrestrial plant diversity manipulations have found that plant biomass increases with diversity, but most marine studies find little or no effect of seaweed diversity on producer biomass or production. However, differences in experimental approach (field vs. mesocosm) and duration (years vs. weeks) between published terrestrial and marine experiments confound the interpretation of these differences in response to changing diversity. We conducted a three-year field manipulation of seaweed diversity on intertidal rocky reefs in central California, USA, to examine the effect of diversity on seaweed cover. We found that diversity increased standing algal cover and decreased the availability of free space relative to monocultures, but this effect took nine months to materialize. Furthermore, diverse assemblages did not consistently exceed the best performing monocultures until 18 months after the experiment was initiated, suggesting that the effect of diversity strengthens over time. Overall, diversity's effect was consistently stronger than that of individual species and not attributable to the influence of any particular species (sampling effect) because (1) polycultures eventually achieved higher cover than even the best performing monoculture and (2) monocultures rarely differed much, precluding a strong sampling effect. Instead, mechanisms such as facilitation and differential use of microhabitats in a heterogeneous environment likely caused the higher cover in polycultures. Our findings contrast with short-term experiments with other seaweeds but are similar to longer-term experiments with terrestrial plants, suggesting that experimental design and approach, rather than inherent differences between marine and terrestrial ecosystems, underlie contrasting responses among systems. We argue that experiments conducted in the field, and for a greater length of time, allow for the manifestation of a greater number of potential mechanisms of overyielding in diverse communities, increasing the likelihood of observing a strong diversity effect.