khadijeh asghari; hamid jalilvand; hamed asadi
Abstract
Introduction: Species diversity is a combination of two interrelated components of species richness and evenness. The first component is the species richness, which is related to the number of species in the sampling unit; The second component is evenness, which refers to the distribution of species ...
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Introduction: Species diversity is a combination of two interrelated components of species richness and evenness. The first component is the species richness, which is related to the number of species in the sampling unit; The second component is evenness, which refers to the distribution of species in the site. One of the important problems of these indicators is not determining the contribution of these two components in the diversity index value. An effective method that has been developed for this purpose is called SHE. The aim of this study was to investigate the contribution of the diversity of understory species in four natural stands, Acer velutinum Boiss, Alnus subcordata C. A. M. and Cupressus sempervirens. var horizontalis afforestation in the Colet forest.Material and methods: In this research, 40 square plots with an area of 400 square meters, were selectively used for sampling in the study area. Then, the list of all herbaceous species with their cover percentage was recorded by Vandermarel criteria. 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.Conclusion: In general, the results of the present study showed that the diversity of herbaceous species due to species composition in the natural stand had the highest value in this region. Also, richness and diversity of woody plants in natural stand and broadleaves reforestation stands were higher than coniferous reforestation. Therefore, reforestation with broadleaves species has a positive effect on the diversity in the region. Also, the effective factor on the diversity indices in the four stands was the richness component (Ln S), which means that severe changes and fluctuations in plant species and their composition was observed.
Mohammad Hasan Naseri; Mohammad Rostamian
Abstract
Introduction: Considering the importance of forest roads and their positive and negative effects on the forest ecosystem, in this study, the effects of a forest road on species diversity indices related to trees and shrubs in forests of Pasargad city were investigated. Material and methods: After field ...
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Introduction: Considering the importance of forest roads and their positive and negative effects on the forest ecosystem, in this study, the effects of a forest road on species diversity indices related to trees and shrubs in forests of Pasargad city were investigated. Material and methods: After field surveys, 30 plots of 400 square meters (20×20 m) were placed on both sides of the road perpendicular along the third-grade forest road with a distance of 100 meters in 0 to 20, 40 to 60 and 80 to 100 m intervals and the species of trees and shrubs were investigated. Then, richness and uniformity indices were calculated and the mean of each index was measured at similar intervals. Then, in SPSS software, the data were normalized by the Kolmogorov-Smirnov test as well as homogeneity analysis of variance using Leven's test. The effect of distance from the road on diversity, richness, and uniformity was determined using a one-way ANOVA method, and Duncan's test was also used to compare the multiple means. Results and discussion: The results of the census of the trees in the study area showed that Amygdalus lycioides species had the highest and Ephedra foliate species had the least abundance in the plots. According to the results, the mean values of diversity, richness, and uniformity indices at different distances from the road showed no significant difference. Also, analysis of variance for values of diversity, richness, and evenness indices at specified intervals showed that there was no significant difference in the 95% confidence level between the values of these indices at different distances from the road. Conclusion: Light competition is one of the factors affecting the establishment of trees and shrubs. There was no light competition in the study area due to the long distances between trees and, therefore, the presence of roads in these conditions wouldn’t affect the light competition. On the other hand, the results showed that with increasing distance from the road, there were no significant differences between the density of trees and shrubs and species diversity indices. Third-grade forest roads are used during limited seasons of the year due to limited infrastructure and pavement, and so the adverse effects of human presence would be limited. Therefore, increasing the distance from third-grade forest road in the study area did not affect the richness, diversity, and evenness of tree and shrubs species.
Behrouz BehrouziRad; Paivand Maktabi; Alireza Jafarnajadi
Volume 13, Issue 2 , July 2015, , Pages 1-10
Abstract
Fluctuation of diversity and population composition of birds are tow bio-indicators of environmental health. For this reason diversity and population composition of birds of Shady island in Karon River in Ahwaz implemented in winter and spring 2014. Area of the park is 17 hectare and adjoin by a bridge ...
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Fluctuation of diversity and population composition of birds are tow bio-indicators of environmental health. For this reason diversity and population composition of birds of Shady island in Karon River in Ahwaz implemented in winter and spring 2014. Area of the park is 17 hectare and adjoin by a bridge to the west of Karon river coast. During winter and autumn we recognized 37 species of birds by telescope and binocular (10 X 40) which belonged to eighteen family. In winter 1414 individuals belong to 23 species and in spring 1036 individuals belong to 29 species counted by total count method. Average density of birds was 83 individuals in winter and 61 in spring in per hectare. Population compound of birds were Ciconiformes and Passeriformes. Most number of birds counted in January and (688 individuals belong to 27 species) lowest was in April. Ardeidae family with 5 species had highest diversity and 10 Family with one species had lowest diversity. The Egretta garzetta with 437 and Larus ridibundus with 576 individuals were dominant in the Shady island.
