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ABSTRACTIn fire-influenced savanna ecosystems, native and invasive exotic plants may use different abilities to coexist and compete for nutrients available in post-fire soil. The availability and uptake of nitrate by two C4 grasses (Urochloa brizantha(exotic invasive) and Axonopus siccus(native)) were characterized in an unburned area and in a recently burned area in the Cerrado of Southeastern Brazil. Ecophysiologic tests were performed to measure Nitrate Reductase Activity (NRA) and nitrate content in leaves and roots. Soil fertility was also analyzed. In the unburned area, organic matter (25.3 ± 2.4 g kg−1), phosphorus (19.0 ± 2.0 mg dm−3), and nitrate (19.9 ± 7.4 mg dm−3) levels were higher than in the recently burned area, which had 27% less cations in the soil. In comparison with soils from the recently burned and unburned areas, ashes of the recently burned area had higher pH, electrical conductivity and nitrate, potassium, and calcium contents. In both areas, the aboveground part of U. brizanthawas more responsive to nitrate compared to A. siccusand both had low belowground NRA. This confirms the working hypothesis that the two species undergo distinct ecophysiologic processes and indicate the adaptive potential of U. brizanthato bypass soil nutrient limitation.

We conducted preregistered replications of 28 classic and contemporary published findings, with protocols that were peer reviewed in advance, to examine variation in effect magnitudes across samples and settings. Each protocol was administered to approximately half of 125 samples that comprised 15,305 participants from 36 countries and territories. Using the conventional criterion of statistical significance (p< .05), we found that 15 (54%) of the replications provided evidence of a statistically significant effect in the same direction as the original finding. With a strict significance criterion (p< .0001), 14 (50%) of the replications still provided such evidence, a reflection of the extremely high-powered design. Seven (25%) of the replications yielded effect sizes larger than the original ones, and 21 (75%) yielded effect sizes smaller than the original ones. The median comparable Cohen’s ds were 0.60 for the original findings and 0.15 for the replications. The effect sizes were small (< 0.20) in 16 of the replications (57%), and 9 effects (32%) were in the direction opposite the direction of the original effect. Across settings, the Qstatistic indicated significant heterogeneity in 11 (39%) of the replication effects, and most of those were among the findings with the largest overall effect sizes; only 1 effect that was near zero in the aggregate showed significant heterogeneity according to this measure. Only 1 effect had a tau value greater than .20, an indication of moderate heterogeneity. Eight others had tau values near or slightly above .10, an indication of slight heterogeneity. Moderation tests indicated that very little heterogeneity was attributable to the order in which the tasks were performed or whether the tasks were administered in lab versus online. Exploratory comparisons revealed little heterogeneity between Western, educated, industrialized, rich, and democratic (WEIRD) cultures and less WEIRD cultures (i.e., cultures with relatively high and low WEIRDness scores, respectively). Cumulatively, variability in the observed effect sizes was attributable more to the effect being studied than to the sample or setting in which it was studied.

ABSTRACTResearchers have argued that power poses are an effective way for individuals to empower themselves to achieve personal goals. However, in laboratory studies, individuals are often unaware of the function of the poses; in real-world settings, participants must knowthe function of the pose in order to deliberately use it. We tested whether power poses are effective when an individual knows their consequences by directly manipulating awareness of the function of power poses. We found no evidence for the overall effect of power poses or an interaction with awareness on both traditional measures of power and a more ecologically valid assessment. Our results suggest the benefits of using power poses outside laboratory settings are limited.