A leap forward in geographic scale for forest ectomycorrhizal fungi

Published versio

Critical slowing down near the smectic-A-hexatic-B transition

We have performed high-resolution heat-capacity and thermal-conductivity investigations on the same sample in the vicinity of the smectic-A-hexatic-B transition of n-propyl-4'-n-heptyloxybiphenyl-4-carboxylate (370BC). The thermal diffusivity shows a pronounced drop near the transition. This clearly demonstrates and confirms the critical slowing down of the thermal fluctuations observed in the other member of the homologous series. The anomaly is found to be in quantitative agreement with the conventional theory of critical dynamics.Nous avons fait des mesures de capacité calorifique et conductivité thermique, avec une grande résolution, sur un échantillon de n-propyl-4'-n-heptyloxybiphényl-4'-carboxylate (370BC) au voisinage de la transition smectique A-hexatique B. La conductivité thermique a une forte décroissance près de la transition, ce qui montre clairement et confirme le ralentissement critique des fluctuations thermiques, déjà observé sur des échantillons de séries homologues. On vérifie que l'anomalie est en accord quantitatif avec la théorie classique de la dynamique des phénomènes critiques

Increasing effects of chronic nutrient enrichment on plant diversity loss and ecosystem productivity over time

Human activities are enriching many of Earth’s ecosystems with biologically limiting mineral nutrients such as nitrogen (N) and phosphorus (P). In grasslands, this enrichment generally reduces plant diversity and increases productivity. The widely demonstrated positive effect of diversity on productivity suggests a potential negative feedback, whereby nutrient-induced declines in diversity reduce the initial gains in productivity arising from nutrient enrichment. In addition, plant productivity and diversity can be inhibited by accumulations of dead biomass, which may be altered by nutrient enrichment. Over longer time frames, nutrient addition may increase soil fertility by increasing soil organic matter and nutrient pools. We examined the effects of 5–11 yr of nutrient addition at 47 grasslands in 12 countries. Nutrient enrichment increased aboveground live biomass and reduced plant diversity at nearly all sites, and these effects became stronger over time. We did not find evidence that nutrient-induced losses of diversity reduced the positive effects of nutrients on biomass; however, nutrient effects on live biomass increased more slowly at sites where litter was also increasing, regardless of plant diversity. This work suggests that short-term experiments may underestimate the long term nutrient enrichment effects on global grassland ecosystems.DATA AVAILABILITY: Data are publicly available on the Environmental Data Initiative platform (Seabloom et al. 2020 https://doi.org/10.6073/pasta/d78e6e48df246a03129c85a6c1da00d6).National Science Foundation Research Coordination Network programs and University of Minnesota’s Institute on the Environment (DG-0001-13).http://www.esajournals.org/loi/ecolpm2021Mammal Research InstituteZoology and Entomolog