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Background and Aims: Re-vegetation of contaminated and disturbed landscapes can reduce the transport of toxic elements while improving soil fertility. This study evaluated whether the planting of a perennial grass with diazotrophic microbial endophytes and municipal waste compost—alone and in combination—improved phytostabilization of potentially toxic trace elements in dolomite-amended tailings from a historically mined polymetallic mineral deposit.Methods We grew Bouteloua curtipendula seedlings in tailings with hazardous concentrations of As, Cd, Pb, Mn, and Zn. We evaluated how plant growth, organic matter accumulation, and minor and trace element mobilization responded to microbial endophyte and organic amendments.Results Although most of the added endophytes were not uniquely identified, the best plant growth and fertility outcomes were achieved with a combination of amendments: dolomite to reduce acidity, a compost topdressing to accumulate nitrogen in the tailings, and a mixed consortium endophyte seed coating to synergistically increase organic carbon and grass biomass yields. Combining amendments also improved phytostabilization: compost reduced the shoot forage toxicity of B. curtipendula seedlings without reducing phytostabilized contaminant yields in the rhizosphere, while endophyte inoculated grass marginally reduced total and water-extractable concentrations of toxic trace elements through enhanced mobilization.Conclusion The most effective means of reclaiming these acidic, polymetallic tailings is with a simultaneous dolomite, compost, and endophyte seed treatment.

1. Microbial necromass is a large, dynamic and persistent component of soil organic carbon, the dominant terrestrial carbon pool. Quantification of necromass carbon stocks and its susceptibility to global change is becoming standard practice in soil carbon research. However, the typical proxies used for necromass carbon do not reveal the dynamic nature of necromass carbon flows and transformations within soil that ultimately determine necromass persistence. In this review, we define and deconstruct four stages of the necromass continuum: production, recycling, stabilization and destabilization. 2. Current understanding of necromass dynamics is described for each continuum stage. We highlight recent advances, methodological limitations and knowledge gaps which need to be addressed to determine necromass pool sizes and transformations. We discuss the dominant controls on necromass process rates and aspects of soil microscale structure including biofilms and food web interactions. The relative importance of each stage of the continuum is then compared in contrasting ecosystems and for climate change drivers. 3. From the perspective of the continuum, we draw three conclusions to inform future research. First, controls on necromass persistence are more clearly defined when viewed through the lens of the continuum; second, destabilization is the least understood stage of the continuum with recycling also poorly evidenced outside of a few ecosystems; and third, the response of necromass process rates to climate change is unresolved for most continuum stages and ecosystems. 4. Future mechanistic research focused on the role of biotic and abiotic soil microscale structure in determining necromass process rates and the relative importance of organo–mineral and organo–organo interactions can inform necromass persistence in different climate change scenarios. Our review demonstrates that deconstructing the necromass continuum is key to predicting the vulnerability and persistence of necromass carbon in a changing world.

In the current work, we investigated whether capuchin monkeys preferred densely distributed resources to sparsely distributed resources in a 2-choice discrimination task with edible rewards. Capuchin monkeys were biased to select a denser food set over the same number of food items in a sparsely arranged set. Furthermore, increased density of the larger food set facilitated discrimination performance in quantity comparisons with a true difference in set size. These results align with previous studies demonstrating a preference for densely distributed food sets in infants and callitrichid primates, as well as previous evidence of a density bias among several rhesus macaques and capuchin monkeys in a computerized relative quantity discrimination task. Thus, the density bias appears to emerge across multiple domains and presentation formats for some primate species. The role of density in perceived numerosity by capuchin monkeys and other species as it pertains to the foraging domain is discussed. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

To test for evidence of metacognition in capuchin monkeys (Sapajus apella), we analyzed confidence movements using a paradigm adapted from research with chimpanzees. Capuchin monkeys provide an interesting model species for the comparative assessment of metacognition as they show limited evidence of such cognitive-monitoring processes in a variety of metacognition paradigms. Here, monkeys were presented with a computerized delayed matching-to-sample (DMTS) memory test in one location but were rewarded for correct responses in a separate location. Movements could be made from one location to the other at any time, but movements between a response and reward feedback may reflect confidence in the accuracy of the response. Critically, DMTS tests included occasional “no sample” trials where monkeys' performance was at chance when the trial started without a sample and a 1-s interval to the response options. We predicted that monkeys would (1) perform less accurately (and less confidently) at longer retention intervals, (2) move to the dispenser early more often on trials completed correctly than incorrectly, and (3) show a relation between faster response latency and early movements. Analyses of response times and “go” or “no go” confidence movements before feedback to the reward location suggested that the monkeys were capable of monitoring confidence in their responses. However, their confidence movements were less precise and less flexible than chimpanzees. Overall, this paradigm can reveal potential metacognitive abilities in nonhuman animals that otherwise demonstrate these abilities inconsistently.

We assessed metacognitive monitoring in 3- to 5-year-old preschool children using a non-verbal behavioral paradigm of confidence. Children responded to a variety of computerized tasks, during which rewards could be collected after each trial at a location spatially distant from the computer. Critically, auditory cues indicating performance were delayed by five seconds after each trial. A metacognitive response indicating confidence in their performance would lead children to move towards the reward location before receiving trial feedback. Results indicated that early movements reflected confidence and non-movements reflected uncertainty. Movements differed as a function of task performance (correct vs. incorrect responding) and objective trial difficulty (easier vs. harder trials) across most cognitive tasks. For some tasks, performance and metacognitive movements also varied as a function of age. These data, from a non-verbal measure of confidence, match other reports of emerging metacognition in children in this age range.