جستجوی مقالات مرتبط با کلیدواژه "richness" در نشریات گروه "اکولوژی"

Soil macrofauna plays a critical role in the development of soil structure and provides a variety of ecological functions. The present study aims to compare the biological index of soil macrofauna in broadleaved, coniferous, and mixed stands during growing and resting seasons in Geno protected area, Hormozgan Province, Iran. After a half-hectare broadleaved stand, a half-hectare coniferous stand, and a half-hectare broadleaf-coniferous (mixed) stand in the Geno protected area were selected to identify the soil macrofauna and measure the physical, chemical, and soil properties and their relationship with soil macrofauna, 10 soil samples were randomly collected from different soil depths including under the canopy to a depth of 15 cm, during the growing and resting seasons. The macrofauna were isolated from the soil samples and were then submitted to a laboratory for chemical analysis. Data were analyzed using SPSS26 software. Richness, evenness, and biodiversity indices were compared using t-test, and then ANOVA and Duncan tests were used to compare physical and chemical properties of macrofauna soil in growing and resting seasons. The results showed a significant difference biological index of macrofauna in broadleaved, coniferous, and mixed stands in the growing and resting seasons.Tperesence of macrofauna the soil, their great diversity and activity as one of the key factors in the supply of nutrients and soil fertility can play a constructive role in the health of ecosystems and maintaining its balance

In order to investigate the effect of conservation on vegetation and biodiversity, two areas were studied. The main objectives of this study were to investigate the effect of conservation on biodiversity indicators. This study was conducted in two protected and unprotected areas with an area of ​​90 hectares. In order to harvest vegetation and biodiversity, systematic sampling method was used with the beginning of a random point with a grid size of 150 * 200 meters and a total of 60 samples were collected in two protected and unprotected areas. For harvesting in the tree layer, 400 square meters of sample pieces and for the grass layer, 100 square meters (10 * 10) quadrats were determined and used by the minimum surface method. Values ​​of diversity, uniformity and richness of plant species were obtained and SIV values ​​were calculated for tree, shrub and grass layers. The obtained results showed that the amount of diversity, richness and uniformity in the protected area in grasslands and trees is higher than the unprotected area. The highest SIV value was obtained for hornbeam and winter alder species in the tree layer and the lowest for Oja and Teda pine species. The highest amount of SIV for herbaceous species belonged to the family Asteraceae.

Environmental gradients and land deformation cause gradual changes in non-living factors that affect the density andEnvironmental gradients and land deformation cause gradual changes in non-living factors that affect the density and distribution of species and are important for the spatial distribution of plant diversity. Understanding the ecological processes associated with altitude gradients leads to potential climatic changes in communities. To study the diversity and species richness in the rangeland, two eastern and western slopes were selected in three altitudes of 2000-2400, 2400-2800 and 2800-3200 meters above sea level. Sampling be performed Systematic random. Thus, in each altitude class, three 100-meter transects were placed perpendicular to the slope at a distance of 100 meters from each other, and on each transect, 10 plots of two square meters and in total 180 plots (2 square meters) were located and measured in the area. Then, important ecological indicators such as richness, diversity and uniformity were calculated using PAST software. Statistical analysis of these indicators showed that the most diversity is related to the altitude class of 2400-2800 and 2800-3200 meters and the least of it is related to the altitude class of 2000-2400 meters. Diversity in the east and west directions was not significantly different. Altitude class 2000-2400 meters with east direction has the highest uniformity and the lowest richness. In relation to richness, in the upper two classes of altitude (2400-2800 and 2800-3200 meters) there was the highest amount of richness and the lowest amount of richness was at lower altitudes. However, richness is larger on the western slope than on the eastern slope. The lowest uniformity was observed in the altitude class of 2400-2800 meters and the eastern and western slopes had the same uniformity. In general, with increasing altitude above sea level, diversity and richness have increased in the western geographical direction. Because more than seventy percent of the frequency of precipitation is in of the western slope and at an altitude above 2800 meters due to the cold weather, the amount of richness has decreased.

Application of organophosphate pesticides especially diazinon is a common phenomenon that cause pollution wide area of terrestrial and aquatic ecosystem. Therefore, an investigation of the effect of this organophosphorus pesticide on some beneficial soil microorganisms was investigated. In a laboratory research, diazinon in the concentration of 0, 4, 12, 50 mg.kg-1 was added to the soil and incubated. Then the soil sampled in different time of incubation, after preparing proper dilution, fungi, actinomycete, pseudomonas, intestinal bacteria and azotobacter cultivated in the specific medium in three replicates. The analysis was considered as completely randomized design (repeated measurement test). The effect of diazinon on biodiversity index of the cultivable microorganisms also evaluated.  In comparison to the control, after application of 4 mg.kg-1 diazinon in the soil the frequency logarithm of actinomycete and azotobacter decreased and pseudomonas increased. The frequency logarithm of intestinal bacteria and fungi were similar to untreated soil. In concentration of 12 and 50 mg.kg-1 the frequency logarithm of all the studied microorganisms reduced. Soil richness in the treatment of 4 mgkg-1 diazinon was more than control and significantly decreased in other concentrations. Biological diversity and evenness decreased in all concentrations of applied diazinon but dominance index increased in comparison with the control. Therefore, most studied soil microorganisms were incompatible with these concentrations of pesticide and this could reduce soil health and fertility.

A biodiversity investigation was carried out in the wild pistachio research forest located in southwest of Fars Province between 52˚ 30́́ to 52˚ 40́́ longitude and 29˚ to 29˚ 15́ latitude in an areaof 9374 Ha area. 72 sampling transects fifty meters long were designated using systematic-random design. In each sampling plot a list of bush, shrub, and tree species and their abundance were recorded. The area was divided into 3 slope levels (level 1: >10%., level 2:10%-30%., and level 3: <30 %), 4 aspects levels (north, east, south, and west) and 3 altitudinal levels (level 1: >1,800 m., level 2: 1,800–2,000 m., and level 3: <2,000 m. a.s.l.) using ARC GIS softwear. Data were analyzed using different indices of heterogeneity, richness and evenness by PAST software and were compared in each of the abovedivisions. Gratest heterogeneity and richness indices were observed in area with slope greater than 30%. Results show that the area with 10-30 percent slope has the highest uniformity. Also, indices of heterogeneity and richness showed that north aspect has higher value than the other directions. Evenness indices indicate that the east direction has greater uniformity. Diversity indices among altitudinal levelrevealed that diversity,eveness and richness in altitudes greater than 2000 meter above see level  is more than other altitudinal levels. The results showed that the vegetation diversity of the region are affected by the physiographical condition.

This study aimed to investigate plant species diversity in the ecological species group in relation to the environmental factors. A study area of 216 ha in the southeast of Baghmalek on which seventy 20×20 m plots were established according to the random-systematic method was selected. Soil properties and physiographic factors were recorded at each plot. Herbaceous species composition was recorded using four 1×1 m subplots around the center of the main plot. A cluster analysis and a CCA analysis were undertaken and three ecological groups were identified. The results showed that pH, Nitrogen, cation exchange capacity, organic carbon and clay percentage were the most important factors of the first group, and the indicator species were, Agropyrom trichophorum, Hordeum bulbosum, Aegilops triuncialis. The second group with  Bromus tectorum, Salvia macrosiphon, Bromus danthonia as indicator species could be correlated with clay, organic carbon, Potassium, Phosphorous, Nitrogen, values. Lastly, the third group, characterized by Artemisia aucheri, Astragalus gossypinus, Phlomis persica, Artemisia haussknechtii as the indicator species, could be correlated with the elevation percentage of sand, Bulk Density and EC. We also found that species diversity varied significantly among the groups, and it was the highest in the first group and the lowest in the third group. The results could, therefore, contribute to better evaluation of species diversity and management of the biodiversity.

This study aimed to compare plant species diversity indices (diversity and richness) and some physico-chemical properties of soil among forest, ecotone and rangeland habitats. Vegetation sampling was done randomly at each habitat. One dominant community was selected in each habitat and one key area was distinguished in each community and 8×1m2 plots were randomly established in each key area. In each plot, the list of existing plants and cover percentage for each species were determined and soil samples were taken from depths of 0-10 cm. The Shannon-Wiener and Simpson diversity indices and Margalef and Menhinic richness indices were estimated using PAST software. Physical and chemical characteristics of the soil were compared at three sites by analysis of variance (One Way ANOVA). The results showed that the lowest and highest values of all species diversity and richness were occurred in forest and ecotone habitats, respectively. Bulk density, sand and pH value of soil were significantly the highest in the rangeland. The percentage of clay and organic carbon in forest habitat were higher than the two other habitats. This study revealed the importance of ecotone in preserving the diversity and species richness.

Interrelationships between plants are affected establishment and survival, as a result, knowledge of how these relationships occur can be used for the maintenance of species and improvement and management of rangelands. This study was conducted to evaluate the effect of Astragalus microcephalus on index vegetation under the canopy in semi-steppe rangeland of protected area in Tange-sayad. For this purpose, percentage of vegetation cover under the canopy of this species and its open space adjacent was measured using a flexible plot along the 100 meters transect. The results showed that 30 species under the canopy of Astragalus microcephalus and 33 plant species in the open space adjacent. In the under canopy of Astragalus microcephalus 6 exclusive species such as Chaerophyllum macropodum, Onobrychis gaubae, Salvia ceratophila, Stachys pilifera and Artemisia aucheri existed that mostly related to perennial, palatable and pharmaceutical plants. In contrast, open space exist 9 exclusive species including Centaurea virgata, Hypecum pendulum, Clypeola aspera, Roemeria refrecta and Xeranthemum annum that mostly related to invasive and annuals species plant. Generally, the vegetation index under canopy of Astragalus microcephalus due to moderate grazing livestock in the region less affected to mechanical facilitating of Astragalus microcephalus but the facilitating role of Astragalus microcephalus in preserving of valuable plant species is highly visible.

In order to investigate the effects of range management plans on species diversity, richness and evenness in Semirum rangelands, 52 sites (28 with treated plan and 24 without treated plan) were selected. The non-parametric indices for species richness (Margalof, Menhinick, Jacknife and counting method) and species diversity (Simpson, Camargo, Smith and Wilson and modified Nee) were compared in two management plans. The mean comparisons were made by independent T Student Test and Mann-Witheny U Test, and correlation was determined between diversity indices and vegetation parameters. Based on the results there was no significant difference between the two management systems regarding environmental features, while the implementation of range management plans caused significant reduction of stocking rate. Among the studied indices, evenness of species in sites without treated plan was significantly more than the sites with treated plan. The correlation matrix showed that there was a significant positive correlation between species richness and vegetation cover, production of perennial plans, and the rangeland condition and trend, while evenness showed significant negative correlation with these indices. Generally, implementation of range management plans has considerable effect on increasing climax species, dominance of Bromus tomentellus and it causes improvement of rangeland condition and reduction of evenness. This behavior could be explained by the balance between species competition and grazing pressure. Further, succession process of the studied communities demonstrates domination of some desirable species, high production and less diversity.

Evaluation of plant richness and diversity is important in rangeland ecosystems because biological control، conservation of genetic resources and the control of natural ecosystems are possible by identifying diversity. One of the factors affecting the richness and diversity is animals'' utilization of the vegetation. Therefore، this research was done to study the plant richness and diversity response to different treatments of animals. To this end، four sites with none، half، equal and twice as much grazing capacity were selected. Treatments were identified due to vegetation cover changes، distance from water، distance from the village and grazing times. Using located transects، samples were (systematic randomization) taken from vegetation (transects four and plots 40 and in the area a total of 160 plots were harvested). The results showed that the highest species richness and diversity belonged to sites'' grazing capacity equal and grazing capacity half. But this was the least in the without-grazing site. Thus، animals'' exploiting the rangelands properly (grazing capacity equal and grazing capacity half) can increase the richness and diversity. Lack of rangeland long-term grazing leads to poor plants. So، both severe grazing and long-term exclusion should be avoided. The full protection of rangeland does not necessarily lead to the maximum diversity.

Soil macrofauna biodiversity has an important role in ecosystem services. In order to find how soil macrofauna biodiversity is related to trees and shrubs in riparian forest of Maroon River in Khuzestan province، soil macrofauna were collected using hand-sorting procedure from 0-10 and 10-25 cm soil depths in 50 cm × 50 cm plots، 50 meters from each other on transects 100 meters apart and perpendicular to the river. Totally، 175 sampling plots were taken. In each plot، quantitative characteristics of trees and shrubs were measured. Soil macrofauna abundance and biomass were highest at 0-10 cm soil depth. Macrofauna biodiversity had a stronger correlation with Tamarisk properties than Euphrates poplar. In contrast، macrofauna biodiversity was not different under Tamarisk and Euphrates poplar. But earthworm was higher under Euphrates poplar cover. The most important parameter of soil macrofauna biodiversity in this area was crown cover. Therefore we could state that regardless of tree species، crown cover of these forests should be conserved because it maintains soil macrofauna biodiversity.

Since the roads are considered as one of the indicators of sustainable development and much of the rural dusty roads are passed through the rangelands thus, the effect of roads has a very importance effect on rangeland ecosystems. Near-road rangelands were selected from the edge of the road until 5 meters distance and far-road rangelands were used in 5 to 20 meters from the edge of the road. For measuring canopy cover, production, density, relative importance, richness, evenness and diversity of plants used to 50 m transects and 1 m2 plots were used in each study areas. 4 transects and 40 plots randomly were put along three kilometers of road of Pishkouh Ali-Abad rangelands in the Yazd. Results showed that the road can changes the vegetation composition, production, and cover, therefore,there is reducation in production, canopy cover of near – road. The importance value of shrub species of near road has declined while the importance value of grasses has increased. Richness, evenness and diversity indices were reduced and distribution of plants, moved to the clamps. These factors indicated the site of near- road is less stable and plant community has crossed boundaries of ecological threshold. Therefore, it is suggested that making the rural dusty roads should be implemented with detailed studies and suitable reclamation may be done with paying attention to ecological condition of the study area.

This study was undertaken to investigate the role of forest management in tree diversity، regeneration and vegetation in control and managed parcels of series No. 1 of forestry plan in Khalil-Mahale، Behshahr. Thirty samples with an area of 1000 m2 were systematically and randomly taken with a 100 × 75 m grid in both parcels. In each plot، tree number and species type were recorded. In order to study the vegetation، five micro-plots (1 m2)، one in the center and four others in four main directions (half radius from the center of the plot) were taken in each plot. The type and percentage of herbaceous species were recorded in each microplot. To count the regeneration in the center of the main plot، circular sample plots with an area of 100 m2 were used. To study and compare the biodiversity in the two plots and to calculate the richness and evenness، the Simpson and Shannon-Wiener diversity indices، Margalef and Menhinic indices and the Pilo index were used، respectively، using PAST software. The results showed that the number of plant species was more in managed plots. The biodiversity of woody and herbaceous plants richness indices and regeneration of tree species were higher in managed plots. In fact، the results showed that forest management using single selection method had different effects on woody species regeneration and diversity of herbaceous and tree species.

Livestock grazing is a common human-induced activity with direct and indirect effects even on the ecosystems of protected areas. The present study analyzed the effects of different grazing management methods on species diversity and richness in the steppe rangelands of Saveh، Iran. Data were collected from sixty 2×2 m plots within the areas of three، four-years protected range management projects. Margalef’s and Menhinick''s indices، Simpson and Shannon-Weiner indices، and Pielou''s index were used to evaluate plant species richness، diversity، and evenness، respectively. All data analyses were performed in PAST and SPSS. According to the mean values obtained for Shannon-Weiner index، Nemati rangeland (with rest-rotation grazing system and moderate grazing intensity) and Shirali Baglou rangeland (with continuous grazing throughout the year and high grazing intensity) had high species diversity with no significant differences among them. However، Chagneh rangeland (with continuous grazing for six months and fairly high grazing intensity) had the lowest diversity. Low values of diversity indices indicated low species diversity in steppe rangelands. Moreover، Shirali Baglou rangeland had the highest species richness compared to the other sites. In the other three rangelands، both species richness and diversity decreased with increasing the grazing intensity. Despite poor range conditions in Shirali Baglou rangeland، intensive livestock grazing and the consequent rise in invasive species increased species abundance and hence، resulting in species richness and diversity in the area. Although over-grazing throughout the year can promote plant species richness through increasing annual species، consequent soil degradation and instability of rangeland ecosystem can be expected.

This study aimed to investigate the effect of canopy trees and shrubs: Pistacia atlantica، Amygdalus scoparia، Amygdalus eburnean on the species diversity and richness of soil seed bank. Ten individuals of each species were selected and one quadrate was established in and outside of crown canopy of each species. In each plot، soil samples were collected from 0-5 and 5-10 cm depths. GLM was applied to assess the effect of woody species، canopy cover، and depth of sampling on the characteristics of soil seed bank. The paired t-test was used to compare the diversity and richness of soil seed banks beneath and outside the canopy. The results showed that the highest species richness of soil seed bank was related to Pistacia atlantica، 0. 24، which was significantly higher than the average species richness of soil seed banks in other species Amygdalus scoparia، Amygdalus eburnea with 0. 10 and 0. 14، respectively. Pistacia atlantica had the highest species diversity with 0. 65 compared to the two other species Amygdalus scoparia and Amygdalus eburnean with 0. 48، 0. 53، respectively. Paired t-test results showed that canopy of woody species significantly increased soil seed bank diversity and richness beneath their canopy. Our results indicated that canopy of tree and shrub species in arid region affected positively on soil seed bank preservation.