Determining the contribution of the diversity of understory plant species in broadleaf and coniferous trees reforestation (case study: Colet forest of Mazandaran)

Abstract

Determining the contribution of the diversity of understory plant species in broadleaf and coniferous trees reforestation (case study: Colet Forest of Mazandaran). Environmental Sciences. 20(1): 129-150. Woody species were counted in each sample plot. The grass and wood cover data were imported and analyzed in Excel and PAST software for analyzing of richness (number of species, Margalf richness and Menhenick richness), evenness (Shannon-Wiener), and diversity (Simpson and Shannon-Wiener). The normality and homogeneity of the data were evaluated using Kolmogorov-Smirnov and Leven test, respectively. SHE analysis was used to determine the contribution of each component of richness and evenness. Results and discussion: The results of comparing the mean of different diversity indices related to herbaceous species showed that the four studied stands (natural, Acer velutinum Boiss, Alnus subcordata C. A. M. and Cupressus sempervirens var. horizontalis ) have significant differences in terms of richness (Margalef and Menhinick) (P <0.01). The results of the classification of plants in terms of biological form by the Raunkiaer method also showed that hemicryptophytes have the highest abundance in the study area. Also, the SHE analysis of richness and evenness components for woody regeneration species in the Colet area showed that the evenness of the trend was constant among the four stands and the richness index in the Cupressus sempervirens and natural stands was fluctuating and had an increasing trend. In the Alnus subcordata stand, the evenness and richness indices had the same contribution in determining the diversity of herbaceous species and woody regeneration in this region. In addition, the SHE curve showed that the richness curve (LnS) and the uniformity (Ln E) do not change with each other, and the change in the richness curve is greater than the evenness. This indicates a greater contribution of richness than evenness in the contribution of determining the diversity of data related to herbaceous species and woody regeneration. In fact, this showed that with the increase in the number of samples, only rare species were being added to the list of herbaceous and woody species. S), which means that severe changes and fluctuations in plant species and their composition was observed.