Inter-and intra-specific phenotypic variation of ecological stoichiometric traits in a mixed-oak secondary forest in China

Ecological stoichiometry provides a framework for the balance and flow of elements between organisms and ecosystems.Elemental phenotypes have an important influence on the environmental adaptation and ecological evolution of plants.There have been few reports on inter-and intra-specific phenotypic variations of ecological stoichiometric traits for congeneric species in a mixed forest although such variations are well-documented at the species level at global,regional and local scales.In this study,total carbon(TC),nitrogen(TN),phosphorus(TP)and potassium(TK)were measured in leaves and the elemental phenotypes were statistically analyzed in four species of oaks—Quercus fabri,Q.serrata var.glandulifera,Q.acutissima and Q.variabilis—in a mixed-oak secondary forest in Yushan,Jiangsu,China.The average element concentrations in the four oak species were not relatively higher than previously reported for oaks from world and Chinese flora.Ecological stoichiometry traits were correlated with tree height and diameter at breast height,indicating that phosphorous and potassium were positively correlated with tree size,while carbon was negatively correlated,especially the relationship between oak growth and total carbon or total phosphorus was obvious,and the study concluded that this was because plant growth depended on phosphorus storage and had opposite effects on leaf carbon accumulation.Based on tree plasticity index and the coefficient of variation,there was medium variation in element concentrations.The plasticity index of total carbon levels was the lowest,and that of potassium the highest.Principal component analysis and cluster analysis showed that the intra-specific variation among the four oak species was higher than inter-specific variation.From the perspective of nutrient supply and ecological adaptation,this study creates a foundation for the management of secondary oak forest stands.

Studies on isozymic variation among the South Indian species of Sphaerostephanos

Objective:To explore the identity and phylogenetic relationships among the three medicinally important species of Sphaerostephanos from South India using isozymic profile.Methods:The young fronds were homogenized with 3.5 mL of ice-cold homogenizing buffer in a pre-chilled pestle and mortar.The supernatant was subjected to electrophoresis as described by Anbalagan poly acrylamide gel electrophoresis.Staining solutions for isoperoxidase was prepared as per Smila method for the detection of isoenzymes.Results:A total of six different bands in five different positions with different molecular weight/Rf values and four active zones have been observed in the isoperoxidase enzyme system of Sphaerostephanos.Only one band with MW/Rf 0.399 is common to two different species i.e.Sphaerostephanos arbuscula(S.arbuscula) and Sphaerostephanos unitus(S.unitus).Among the remaining four bands,two bands(R_f.0.23,0.47)are present in Sphaerostephanos subtruncatus(S.subtruncatus) and one distinct band has been observed individually in S.arbuscula(R_f.0.507) and S.unitus(R_f.0.56).Conclusions:The present preliminary molecular study through isozymic analysis shows the identity of all the three species and the present results confirm distinctness of these three species based on macromicromorphology,phytochemistry and cytology.