Investigation on litter invertebrates diversity at natural forests and reforestations of hardwood and softwood in Mazandaran(Case study: Darabkola)

The most important role of the litter invertebrates is leaf litter decomposition and helping of nutrient elements cycling. The objective of this study was to evaluate litter invertebrates dversity within 20 years old plantations of alder (Alnus subcordata C. A. Mey.), maple (Acer velutinum Bioss.), oak (Quercus castaneifolia C. A. Mey.), cypress (Cupressus sempervirens var. horizontalis) and natural forest in Darabkola (Mazandaran-Iran). For this purpose, one sample plot, each 1 ha was selected in every plantation as well as in the natural stand. In each sample plot 10 micro plots, each 100 m2 were selected random-systematically. Litter invertebrates were sampled by removing, by hand, all leaf litter in 100×100 cm quadrats. Fifty samples were taken each time and during four seasons 200 samples were taken. Invertebrates were separated out visually in the lab and transferred to 95% alchol, after sorting and counting. More over, various parameters of the stands and soils were measured in each micro plot. For determination of soil invertebrates diversity in these treatments, Shannon and Simpson indices were used, while for determination of species richness and equatibility, Margalef and Heip indices were applied. The results of this research showed that although the differences between the annual means of litter invertebrates diversity was not statistically significant in studied sites (p=0.05), but the decreasing of diversity index in these treatments was respectively as reforestations of alder, maple, natural forest with cypress and oak reforestations. Also the analysis of PCA showed that the parameters of temperature, crown canopy, relative light intensity, moisture content of soil and litter and the amount of P and C/P of litter take an important role in seasonal differences of litter invertebrates diversity in treatments.