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Background:Cushions are the typical nurse species of high-elevation environments. However, few studies have explored the differences in facilitative power and environmental amelioration between nurse plants of different species that share a common cushion morphology. Aims:To compare the nurse effects of different alpine cushion plants and their mechanism. Methods:We compared the effects of two co-occurring cushion species,Potentilla articulataandArenaria polytrichoideson species richness, Shannon–Wiener diversity and the evenness of vascular plant assemblages in the Himalayas. In addition, we compared the temperature and the soil nutrients within and outside the two cushion species. Results:The presence of either cushion species significantly increased the species richness and diversity in comparison with the areas outside the cushions;P. articulatacushions were associated with greater species richness thanA. polytrichoides. Substrate temperatures were similar under the two species and in open areas, but nitrogen and potassium levels were higher under either of the two cushion species than they were outside. Soil phosphorus and potassium concentrations were significantly higher beneathP. articulatathan beneath theA. polytrichoidescushions. Conclusions:Our results indicate that facilitation of local species richness by cushion plants contributes to the structure of the alpine plant community in the eastern Himalayas. The intensity of the nurse effect varies with the soil nutrient level beneath different benefactor species. [ABSTRACT FROM AUTHOR]

Abstract: Antioxidant activities of the methanol extract, fractions and isolated compounds from the roots of Potentilla fulgens Lodd. were evaluated by three in vitro experiments, namely, ABTS, DPPH, and FRAP assays. PF-2 was characterized as a new biflavanoid and designated as Potifulgene on the basis of NMR and mass spectrum, whereas PF-1 was identified as epicatechin. The activities of aqueous methanolic extract and fractions could be correlated with their respective total phenolic content and compared with standard natural antioxidants such as quercetin, vitamin C and pyrogallol. The root powder of the plant was extracted with methanol/water (80:20) by cold extraction and its extract was further partitioned with ethyl acetate, butanol and water fractions. Among the three fractions (ethyl acetate, butanol and water fraction) and the total aqueous methanolic extract, the butanol fraction exhibited good scavenging response measured in terms of TEAC (mM Trolox equivalent/mg extract). The butanol fraction was found to possess strong antioxidant activity (2.54±0.69, 2.41±0.53, 3.57±0.05mM Trolox equivalent/mg extract) with ABTS, DPPH and FRAP assays, respectively. The chemical composition of extracts, studied in terms of total polyphenol content (TPC), was found in the range of 20.61±0.38 to 33.28±0.11mg/g gallic acid equivalent. A significant correlation was observed between total polyphenolics and antioxidant activity, indicating participation of phenolics in antioxidant activities of extract and fractions. The antioxidant activity of new biflavanoid (Potifulgene) was found to be higher, i.e. 6.85±0.38, 4.24±0.41, 5.35±0.53 than that of epicatechin, 2.13±0.05, 1.50±0.02, 1.57±0.03 with ABTS, DPPH and FRAP assays. [Copyright &y& Elsevier]