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• A field experiment was performed to reveal the hydrothermal behavior of the MACP. • Cement stabilized base is the moisture accumulation zone within MACP. • Central part of the MACP develops a hydrothermal aggregation zone gradually. As one of the widely used pavement materials and structures, the multilayer asphalt concrete pavement (MACP) presents evident heat absorption and hydrothermal accumulation behaviors, which is prone to severe frost and thaw damages in cold regions. A full-scale field experiment was performed to reveal the hydrothermal process within the MACP in Inner Mongolia of China. Based on the continuous three years' monitoring data, the freezing-thawing process, moisture features, and hydrothermal interactions of the MACP were analyzed. The results indicate that: (1) the MACP generates an important heat absorption and storage effect. A high heat flux accumulation zone forms at the central part of the MACP. Compared to the natural surface, the thawing freezing ratio at the bottom of the embankment enlarges 1.65 times armed with the MACP, meaning a dominant thawing process over a year cycle. (2) Under the influence of the thermal effect, moisture migration is considerably active within the MACP. The liquid water content of the MACP varies sharply with the decrease of the temperature. Then the cement stabilized base (CSB) and asphalt treated base (ATB) undergo the maximum and minimum liquid water contents, respectively. Furthermore, a core-shaped moisture accumulation area develops, coinciding with the features of the yearly distribution of the temperature. (3) The heat and mass transfer theory in the unsaturated porous medium was used to separate liquid water flux drove by the temperature gradient within the MACP. The temperature gradient driving effect mainly occurs in cold seasons. Under the impact of the temperature gradient, the ATB layer presents only downwards liquid water movement, while the CSB layer presents upwards and downwards liquid water movements. [ABSTRACT FROM AUTHOR]

• Net genotypic diversity effect of Stipa grandis on biomass was not found. • Rao's quadratic entropy (FD Q) among Stipa grandis genotypes was lower than that among species. • Relatively higher FD Q mainly contributed to net species diversity effect by complementarity effect. Plant diversity exerts significant effects on ecosystem functioning. However, it remains unclear that whether the ecological consequences of genotypic diversity of the dominant species is similar to that of species diversity. In this study, diversity effects on biomass of 12 companion species and 12 genotypes of the dominant species (Stipa grandis) in the Inner Mongolia Steppe of China were examined by two independent diversity experiments. In order to explain the diversity effects, seven plant functional traits for each species or each genotype of S. grandis per mixture treatment were measured and their Rao's quadratic entropy (FD Q) was estimated. There was significantly positive net species diversity effect on aboveground biomass, which was mainly contributed by complementarity effect; however, net diversity effects were not significant in genotypic diversity experiment. The FD Q among S. grandis genotypes was significantly lower than that among the companion species, and the relatively lower FD Q would increase niche overlap and limit complementarity effect among genotypes. Neither species diversity nor genotypic diversity of S. grandis showed significant influences on belowground biomass, suggesting the non-consistent results of diversity effect between belowground and aboveground systems. The present finding highlighted the species diversity effects on biomass, the role of FD Q on explaining complementarity effect by niche overlap or resource use efficient. [ABSTRACT FROM AUTHOR]

Terrestrial plants in natural populations can adjust their morphologies and structures in response to different environmental conditions by genetic differentiation and environmental modification (phenotypic plasticity). The adaptive mechanisms for quantitative variation of 7 Stipa krylovii populations were evaluated using a combination of experiments performed in a field and a common garden. (1) In the common garden experiment, the quantitative traits of S. krylovii differed significantly ( P < 0.05), and high overall differentiation ( D ) was found between populations ranging from 0.53 to 0.97; the first 3 principal components (PCs) could explain 78.4% of the variation among the populations, but only 3/39 pairwise variables showed significant correlations between PC scores and environmental variables. These results indicated that neutral processes might be mainly responsible for the contemporary patterns of phenotypic differentiation of S. krylovii . (2) In the field, populations of S. krylovii differed significantly for all traits ( P < 0.001); the first 3 principal components could explain 80.8% of the variation among the populations, and 5/39 pairwise variables between PC scores and environmental variables showed significant correlations. Only two traits (the lengths of the first and the second glumes) showed similar phenotypic pattern (based on the results of Spearman’s correlation) and similar values (based on the results of paired samples t -tests) between both conditions. These results indicated environmental modification (phenotypic plasticity) played a certain role for the phenotypic differentiation of S. krylovii . (3) Intra-population variability (CV intra ) of S. krylovii was systematically higher than inter-population variability (CV inter ) for all traits, except for the 1000-seed weights in the common garden experiment, suggesting a high potential capacity of S. krylovii to adapt to environmental changes. The results indicate the importance of combining data from field and common garden experiments in order to understand the ecological adaptive mechanism and evolutionary potential of such an important species in view of its phenotypic divergence. [ABSTRACT FROM AUTHOR]