Optical Evidence of Multiphase Coexistence in Single Crystalline (La,Pr,Ca)MnO3

We investigated temperature (T)- and magnetic field-dependent optical conductivity spectra (\s\w) of a La_5/8-yPr_yCa_3/8MnO_3 (y~0.35) single crystal, showing intriguing phase coexistence at low T. At T_C < T < T_CO, a dominant charge-ordered phase produces a large optical gap energy of ~0.4 eV. At T < T_C, at least two absorption bands newly emerge below 0.4 eV. Analyses of (\s\w) indicate that the new bands should be attributed to a ferromagnetic metallic and a charge-disordered phase that coexist with the charge-ordered phase. This optical study clearly shows that La_5/8-yPrCa_3/8MnO_3 (y~0.35) is composed of multiphases that might have different lattice strains.Comment: A single file with 9 figures embedded, to appear in Phys. Rev.

Long-term trends in restored moorland vegetation assemblages

Restoration of moors dominated by Calluna vulgaris is carried out for conservation and sporting reasons. Previous research has shown variable restoration success in the early years of restoration management. In this study we investigated whether restored heather moorland vegetation increasingly resembles long-established moorland vegetation over a longer time period. Vegetation at seven moorland restoration sites (six in northern England and one in Scotland) was sampled in 2003 (to assess short-term restoration success) and 2010 (to assess long-term restoration success). Three of these sites were restored solely by grazing control and four by a suite of more intensive techniques. On each visit, vegetation sampling was carried out in degraded, restored and long-established control areas at each site. Restored vegetation assemblages closely resembled control assemblages. The samples were, though, dominated by the species targeted for management, Molinia caerulea and Nardus stricta in degraded samples and Calluna vulgaris in control samples. Discounting these species and concentrating on the remainder of the vegetation assemblage, areas restored solely by the reduction or removal or sheep grazing more closely resembled control assemblages whilst those managed more intensively were more intermediate between degraded and control assemblages. There was no systematic pattern of change in restored areas between the sampling dates. At two sites restored samples become more similar to control samples whilst restored samples at other sites either showed little change or moved back towards a degraded assemblage. Thus whilst moorland restoration can succeed in re-establishing C. vulgaris, we found no evidence of a systematic shift in the remainder of the vegetation assemblage towards that of a long-established moor over the time period studied

The UK Environmental Change Network: Emerging trends in the composition of plant and animal communities and the physical environment

This review identifies the major trends in physical, chemical and biological data between 1993 and 2007 at the 12 terrestrial sites in the United Kingdom Environmental Change Network (ECN) and assesses the effectiveness of the programme. Temperature and precipitation increased and sulphur (S) deposition decreased across the network. There were also significant local trends in nitrogen (N) deposition. The decreasing S deposition was associated with increasing pH of rainfall and soils and there was widespread evidence of soil pH showing recovery from acidification. Warm-adapted butterfly species tended to increase at northern, upland sites, consistent with an effect of increasing temperatures. In contrast, carabid beetle species associated with cooler northern and upland areas showed declining populations. The increasing trend in precipitation may account for a decline in ruderal plant species in the lowlands, reversing an increase associated with drought in the early part of the time series. There was no general shift in the composition of plant communities which might reflect rising soil pH. This may reflect the slow dynamics of plant community processes or a distinction between pH trends at the surface and lower soil horizons. The ECN is effective in detecting trends in a range of different variables at contrasting sites. Its strength is the ability to monitor causes and consequences of environmental change in the same programme, improving the ability to attribute causes of change, which is essential to developing conservation policy and management in the 21st century

Simple does not mean poor: grasslands and forests harbor similar ant species richness and distinct composition in highlands of southern Brazil

Several studies addressed ant communities in the dense Atlantic Forest that runs along the Brazilian coast. However, comparatively little is known about the mixed forests and grasslands that occur in the southern range of the Atlantic Forest domain. In this study we performed the first standardized assessment of ants in the forest- grassland mosaic found in the highlands of the state of Santa Catarina. We aimed to investigate and compare ant richness and composition between mixed forests and grasslands in the main mountain range of south Brazil. Ants were collected in two years with ground pitfalls, tree pitfalls and litter samples. Sixty ant species were recorded, resulting in 22 new records for “Planalto Serrano” region and three for the state of Santa Catarina: Eurhopalothrix depressa , Pheidole radoszkowskii and Wasmannia williamsoni . There was significant dissimilarity in ant species composition between grasslands and forests, but no difference in ant species richness, even considering the higher number of strata in mixed forests. Similar richness and low number of arboreal species suggest that this ant community is structured similarly to temperate ones. Both habitats presented a large proportion of exclusive species. The fact that species composition between grassland and forest areas differed, coupled with the similarity in species richness between habitats and the record of new ant species for the region, calls for strong conservation efforts in grasslands of southern Brazil, which still are little protected by conservation areas