Moslem Rostampour; Mohammad Saghari
Abstract
Introduction: Each of the different exploitation and management methods in rangelands has different effects on the rangeland ecosystems functions. Incorrect and inappropriate ways of rangelands using, especially in the last few decades, have caused severe damage to the natural resources. There are a ...
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Introduction: Each of the different exploitation and management methods in rangelands has different effects on the rangeland ecosystems functions. Incorrect and inappropriate ways of rangelands using, especially in the last few decades, have caused severe damage to the natural resources. There are a few researches on the effects of grazing on sand habitats of desert areas. The aim of the current research is to investigate the effect of different methods of rangeland utilization on ecological characteristics, including the percentage of vegetation cover, plant density, species richness, diversity, evenness and dominance, and species similarity in the studied rangelands.Materials and methods: This research was conducted in Outskirt, Seminomadic, Settled nomadic and Enclosure in Zirkouh, South Khorasan province. In each rangeland, the list of plant species, density and vegetation cover of each species was determined separately. Also, range condition was evaluated by modified four factors method. In addition to numerical indices, the ranking of species diversity was investigated using the Renyi diversity ordering curve. In order to check the species similarity between the four studied rangelands, Jaccard's similarity index was used, and hierarchical cluster analysis (Euclidean distance and Ward's method) was used to better display the species similarity. Finally, the relationship between vegetation cover and the number of species and biodiversity indices was tested by Pearson's correlation coefficient.Results and discussion: Based on the modified four factors method, the condition of outskirt and seminomadic rangelands were moderate and settled nomadic rangeland was poor and enclosure rangeland, has been evaluated as good. The results of ANOVA showed that the effect of grazing methods on the vegetation cover (at the 0.05 level) and the total and average species richness (at the 0.01 level) were significant. Enclosure rangeland has the highest plant cover percentage and plant density (54.73% and 80, respectively) and the settled nomadic rangeland has the lowest plant cover percentage and plant density (15% and 5, respectively). The highest species richness belongs to enclosure rangeland and there is no difference between other rangelands. Compared to other rangelands, the seminomadic rangeland has the highest proportion of native plants and the lowest proportion of increaser plants in the plant composition of total richness. The highest proportion of increaser plants is observed in settled nomadic rangelands. In terms of species diversity, enclosure rangeland has the highest Shannon-Wiener diversity index (2.03) and Simpson diversity index (0.80) compared to other rangelands. The results of the correlation coefficients of vegetation cover and the number of species and species diversity indices showed that, in general, the diversity indices and vegetation cover and the number of species have a significant positive correlation, and the species evenness and dominance indices and vegetation cover and the number of species have a significant negative correlation. The results of the Jacquard similarity index show that the highest degree of species similarity is observed between the outskirt and the settled nomadic rangelands (62%).Conclusion: The results showed that the overgrazing around the livestock pen in the settled nomadic rangeland is clearly visible and it has led to a significant decrease in vegetation cover, plant density and species diversity. Resting to rangelands (in the enclosure) and delay grazing (in seminomadic rangeland) can also enhance vegetation and biodiversity. In terms of the percentage of vegetation cover, density and plant composition, the seminomadic rangeland is located is next to the enclosure. The most proportion of forage species was observed in the plant composition of the seminomadic rangeland. If we accept the hypothesis that range enclosure causes the plant succession towards the climax stage and in range management, the sub-climax stage is always better than the climax stage, in this case, in terms of livestock and range management, the temporary settlement of nomads will be more beneficial than range enclosure.
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.
Mohammad Reza Asgharipour; Fatemeh Kamari; Mahmoud Ramroudi; Yaser Alizadeh
Abstract
Introduction: Diversification of agriculture is considered an important strategy to overcome the challenges faced by many developing countries due to the opportunities it offers to face heterogeneous production conditions, increase income generation through entry into new markets, and risk management. ...
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Introduction: Diversification of agriculture is considered an important strategy to overcome the challenges faced by many developing countries due to the opportunities it offers to face heterogeneous production conditions, increase income generation through entry into new markets, and risk management. Conservation of biodiversity is one of the sustainable development concepts in agriculture. Excessive attention to the number of products and the extreme use of off-farm inputs, regardless of other ecological functions of these systems, has led to the reduction of biodiversity at all levels. In this context, a comprehensive plan for monitoring crop diversity and identification of factors influencing diversification is necessary. Accordingly, this study was conducted to evaluate the temporal and spatial changes in the biodiversity of agricultural systems in the Ilam province during 2004 and 2016. Material and methods: Data were gathered from statistical yearbooks and reports from the Plan and Budget Organization and Organization of Jihad Agriculture. Stepwise regression analysis was used to identify the factors influencing regional crop diversity fluctuation over time (Also, stepwise recursive regression analysis was used to evaluate the determinant factors in the changes of diversity in agricultural systems.). In order to evaluate the spatial variation of crop diversity in irrigated agroecosystems and its determinants factors, the Shannon-Weiner diversity index was calculated. Based on the assumptions of the study, the influencing factors on the spatial variation of crop diversity were classified into geographical factors, climate and ecological factors, sociocultural factors, economic factors, and management factors. Then, insignificant factors on crop diversity were excluded from the model and finally, the most important determinant on variations between different regions of the province remained in the model. Results and discussion: The findings of this study revealed that over the 12-years period, the general trend in the changes of production systems was a decreasing one; so the agricultural systems’ diversity in all counties, except for Ilam and Dehloran, had decreased, of which the highest value of the Shannon-Weiner diversity index was calculated 1.90 in 2016. The main reason for this increase in diversity was the increase in the number of vegetable crops and reducing the area under cultivation of dominant crops (wheat and barley) during the studied period. Furthermore, the main determinant factors of diversity in the agricultural systems of Ilam Province were the number of villages with inhabitants, average annual net income of a rural household, number of cooperatives, number of dusty days, agricultural land areas, number of production units, age of the beneficiary, minority percentage, amount of urea fertilizer, number of family members, and literacy rate, respectively. Conclusion: Studying the critical points in the agricultural systems of Ilam Province indicated that the top-priority actions to improve sustainability and increase the diversity of these systems are educating farmers, helping them reach economic stability and improving production management and water resources management.
Roshanak Torabi; Shahrokh Pashaei Rad; Mohammad Reza Shokri
Volume 15, Issue 3 , October 2017, , Pages 75-92
Abstract
Introduction:
Ants are the most well-known social insects that have a significant impact on the ecosystems of their habitat. The role of these insects in the physical and chemical changes of the soil and their interaction with plants, microorganisms and other living organisms is undeniable. Iran with ...
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Introduction:
Ants are the most well-known social insects that have a significant impact on the ecosystems of their habitat. The role of these insects in the physical and chemical changes of the soil and their interaction with plants, microorganisms and other living organisms is undeniable. Iran with extensive climate conditions and diverse of habitats, has vast variety of plants and animals specie. Family Formicidae fauna in Iran is far from complete and yet 213 species of 32 genera and 4 subfamilies has been reported.
Materials and methods:
The present investigation deal with the study of ant fauna in Shiraz city. The area was divided into 18 study sites with different ecological factors. Samples were collected equally in times and numbers in the spring, summer and fall season 2014. Collected species were transferred to 70% alcohol and identified with the help of stereomicroscope and available keys. The identified specimens were confirmed by Professor Brian Taylor in Royal Entomological Society of London in England. Ecological condition effects(as altitude, soli sedimentary organic matter (TOM), temperature, air humidity, soil humidity, soil pH and soil grading) on species richness were collected from study sites and analyzed by linear regression test using SPSS22.
Results and discussion:
Among the identified specimens, 19 species belonging to 13 genera of 3 subfamilies were identified which are as below: Subfamily Dolichoderinae: Tapinoma simrothi Krausse, 1911 Subfamily Formicinae: Camponotus (Tanaemyrmex) xerxes Forel, 1904; Camponotus (Myrmosericus) armenaicus Arnol'di, 1967; Camponotus (Tanaemyrmex) aethiops (Latreille, 1798); Camponotus (Tanaemyrmex) sanctus Forel, 1904; Cataglyphis nodus (Brullé, 1833); Cataglyphis frigidus subspecies persicus (Emery, 1906); Lepisiota semenovi (Ruzky, 1905); Lasius turcicus Santschi, 1921; Paratrechina vividula (Nylander, 1846)Subfamily Myrmicinae: Cardiocondyla persiana Seifert, 2003; Crematogaster sp. (sp undet cf Safariyan, 2014); Messor melancholicus Arnol’di, 1977; Messor syriacus Thomé, G., 1969; Messor rufotestaceus (Foerster, 1850); Monomorium kusnezowi Santschi, 1928; Pheidole pallidula (Nylander, 1849); Pheidole teneriffana Forel, 1893; Tetramorium davidi Forel, 1911Conclusion: All the identified species except T.simrothi, C.frigidus, C.persiana, M.rufotestaceus and P.teneriffana were recorded for the first time from Fars Province and the species T.simrothi and P.teneriffana were recorded for the first time from Shiraz City.
Conclusion: Statistical analysis using linear regression in SPSS22 shows a significant difference between pH and species richness of ant communities.
Masoud Ghazvini; Hadi veisi; Abdolmajid Mahdavi-Damghani; Korous Khoshbakht; Mohammad Ali Nejatian
Volume 14, Issue 2 , July 2016, , Pages 13-22
Abstract
As biodiversity declines, the ability of agro-ecosystems to produce ecosystem services such as food security deteriorates. Despite the important role of grape in the livelihood of communities that produce this crop and also its high potential for export, very few studies have been conducted on the status ...
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As biodiversity declines, the ability of agro-ecosystems to produce ecosystem services such as food security deteriorates. Despite the important role of grape in the livelihood of communities that produce this crop and also its high potential for export, very few studies have been conducted on the status of biodiversity in grape production ecosystems and its relationship with different indices of productivity and stability. The data presented here were collected during face-to-face interviews with 220 grape orchardists in 2011. Results showed negative significant correlations between the Shannon-wiener index with total productivity (- 0.175**), water productivity (- 0.19**), land productivity (- 0.173**) and labour productivity (- 0.202**) as well as correlations between species richness with land productivity (- 0.14*). These results indicate negative relationship between changes in biodiversity of grapevine varieties with vineyard’s productivity and imply the long-term sustainability of the vineyards in Takestan County. Regression analysis showed that the explanation coefficients (R2) were between 0.03-0.04. We tentatively conclude from this that a 1% change in BD corresponds to approximately a 0.03-0.04% change in the value of productivity. The results also showed that the varietal diversity of vineyards have no effect on vineyards’ yield stability.
Lale Amozgar; Jamshid Ghorbani,; Maryam Shokri; Seyed Hassan Zali
Volume 12, Issue 4 , January 2015
Abstract
Environmental factors particularly soil properties influence the species composition and vegetation diversity in rangelands. Soil in some parts of lowland areain Mazandaran province is saline. This made some limitations for establishment of vegetation. In this study the relationship between vegetation ...
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Environmental factors particularly soil properties influence the species composition and vegetation diversity in rangelands. Soil in some parts of lowland areain Mazandaran province is saline. This made some limitations for establishment of vegetation. In this study the relationship between vegetation and soil properties were assessed in lowland rangeland of Hyrcanian zone in the city of Behshahr, Mazandaran Province. Vegetation was sampled along transects with 100 m length using 1 m2plots. Cluster analysis showed six vegetation types. ANOVA results indicated that greater values of species richness and diversity indices were found in Artemisia sieberi-Medicago rigidulaand Halocnemum strobilaceum-Juncus maritimus. Results from RDA analysis showed that salinity, soil texture and soil moisture are main drivers of vegetation distribution in this area. An increase in EC,CaCo3andsilt was associated with the establishment of Salicornia europaea-Spergularia marinaand Halocnemum strobilaceum-Juncus maritimus. Aeluropus littoralisand Hordeum marinum-Plantago psylliumwere found where soil had lower EC but higher moisture, Organic carbon and clay. A reduction in soil EC and soil moisture was the favorite of Artemisia sieberi-Medicagorigidulaand Juncus maritimus.
Karl Hammer; Korous Khoshbakht
Volume 7, Issue 3 , April 2010
Abstract
Species richness in relation to crop plants is analyzed within the families of higher plants. Three groups have been made: (1) more than 10.000 species (5 families), (2) 1.000 to 10.000 species (50 families), (3) less than 1.000 species (20 families). Thus about 224.000 species from the estimated 250.000 ...
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Species richness in relation to crop plants is analyzed within the families of higher plants. Three groups have been made: (1) more than 10.000 species (5 families), (2) 1.000 to 10.000 species (50 families), (3) less than 1.000 species (20 families). Thus about 224.000 species from the estimated 250.000 species of higher plants have been included in this study. According to Hanelt and IPK (2001), altogether 7,000 species of crop plants exist. There is a positive correlation (r = + 0.56) between the number of crop plants and species diversity of the families. Important crop species within the selected families are indicated.
