Showing 7 results for Species Richness
Engineer Reza Omidipoor, Dr Reza Erfanzadeh, Dr Marzban Faramarzi,
Volume 9, Issue 4 (3-2016)
Abstract
Species diversity differs in various spatial and temporal scales in response to different biotic and abiotic conditions. The aim of this study was to investigate the effects of grazing impact on species diversity components in local and regional scales in Ilam province. Vegetation sampling was carried out using 40 plots of 2×2 m2 (20 plots in exclosure and 20 plots in grazed area) in local scale and 8 sites (4 sites within exclusion and 4 sites within grazed area) in regional scales. Plant species richness (γr) partitioned into additive component among plots (α1), between plots (β1) and between sites (β2). We used the PARTITION software for analysis of species diversity components in different scales. According to the results, 72 plant species were observed in exclosure and 60 species in grazed area from a total of 89 recorded plant species. Additive partitioning of plant species diversity showed that, in two regions, observed plant species components (α1 and β1) was smaller than expected values in local scale, and in regional scale and observed plant species components (β2) was greater than the expected value. Species diversity among plot (α1) in exclosure area was significantly greater than the grazed area, but there was no significant trend for species diversity between plots (β1) and sites (β2), indicating non-random patterns of plant species. The beta diversity, with respect to more contribution to total species diversity, was more important diversity component in regional scale. This study showed that some components are more sensitive to grazing, so we suggest using these indices in vegetation management studies.
Parisa Niknam, Reza Erfanzadeh, Hassan Ghelichnia,
Volume 11, Issue 4 (3-2018)
Abstract
This study aimed to assess soil seed bank condition under cushion plants in response to prescribed fire in Vaz watershed, Mazandaran province. Thirteen cushion plant stands were selected randomly. Soil samples of pre-fire condition were collected at two depths (0-5 and 5-10 cm), then the cushion plants were treated by experimental fire and soil samples were collected again one week after the fire treatment. The sampled soil seed banks were evaluated using germination tests in greenhouse condition. Germinated seeds were identified and the seed density per square meter and species richness were calculated. Two-way ANOVA and paired t-test were applied to evaluate the effects of fire, soil depth on soil seed bank density and richness. The results showed that seed density of forbs and grasses at pre-fire in the depths of 0-10cm was significantly higher than those of forbs and grasses at post-fire treatment at the same depth (p < 0.05). Similarly, species richness of forbs and grasses at the pre-fire condition at the depth of 0-10 cm was significantly higher than those at the same depth in post-fire condition (p < 0.05). Seed density and species richness of seed bank at the pre-fire condition in the depth of 0-5 cm was significantly higher than those at post-fire (p < 0.05). No significant differences were observed between pre and post-fire at depth of 5-10 cm in density and richness of soil seed bank.
Mohammadreza Mirzaee, Parviz Gholami, Esfandiar Jahantab,
Volume 12, Issue 3 (11-2018)
Abstract
Evaluating the positive or negative effects of management practices in rangeland ecosystems is highly important for developing appropriate restoration plans. This study aimed to evaluate the effects of biological practices on species composition and diversity in semi-Steppic rangelands of Zagros in Kohgiluyeh and Boyer-Ahmad Province. A random systematic method was used to collect vegetation data from 120 quadrates of 1 m2 in the sites under seedling planting, pit-seeding and heavy grazing condition. The species composition, diversity (Simpson, Shannon-Wiener), richness (Margalef and Menhinick) and functional groups (e.g. longevity, growth form, life form, and family) of various range sites were compared. The result of this study showed that biological restoration practices significantly influenced diversity, species richness indices and some functional groups (P <0.05). The sites under seedling planting and pit-seeding showed the highest species richness, diversity. The functional groups including perennials, Hemicryptophytes, grasses, forbs, Apiaceae, Poaceae, and Rosaceae family were more abundant in the treated sites compared to the heavily grazed site. RDA analysis showed that high range value species such as Ferula assa-foetida، Prangos ferulacea and Dorema aucheri were more abundant significantly compared to the control site. Overall restoration practices had positive effects on vegetation condition in the study area.
Akram Sohrabi, Jamshid Ghorbani, Ghodratolla Heydari, Shafagh Rastegar,
Volume 12, Issue 4 (1-2019)
Abstract
Monitoring and assessment of restoration projects could determine the vegetation dynamic and the success rate of he the project. This study aimed to evaluate the effects of Prangos ferulacea pit-seeding on species composition and species richness and diversity in Dalvara and Kalvary in Chaharmahal and Bakhtiari province in two different years. Cover percentage of the species and also the density and biomass of P. ferulacea were measured in two treated sites (one in 2007 and another in 2011) and one control site (no treatment). Results showed that the cover and density of P. ferulacea was significantly greater in the sites treated in 2007 than the sites treated in 2011. Also, six years after the treated site of 2007, the biomass of P. ferulacea was twice than that of 2011. A total of 71 species were recorded of which 39 species were common among the two sites. The cover percentage of 14 species significantly reduced in the treated sites. Chardinia orientalis, Hordeum bulbosum, Taeniatherum crinitum, and Tragopogon longirostris showed a significant increase in 2007 while they reduced significantly four years later. The cover percentage of grasses were decreased by 80 percent due to P. ferulacea pit-seeding in 2011. Although similar annual species were found in the treated and the control site, their cover percentage was reduced significantly in the treated site due to a dense stand of P. ferulacea. The species richness and diversity were reduced under P. ferulacea pit-seeding. These indices also showed a significant negative correlation with cover percentage of P. ferulacea. The result showed that this project increased forage production but the effects of P. ferulacea on vegetation characteristics varied considerably based on the time laps of post-pit-seeding.
Esfadyar Jahantab, Mohamadreza Mirzaee , Parviz Gholami,
Volume 13, Issue 2 (7-2019)
Abstract
Preserving species diversity is one of the important objectives of ecosystem management. The aim of this study is to investigate the effect of drill seeded enclosures on vegetation changes in Tang-e-Sorkh rangelands in Boyerahmad province, Iran. Samples were taken from two areas: a 10 years exclosure plus drill seeding with Ferula assa-foetida L. and an area which is currently grazed as the control site. For sampling purpose, three 100-meter transects were put in each area, then for every ten meters of the transect a plot of one square meter was installed. Species richness were assessed through well known indicators, such as Sheldon's evenness index, Shannon entropy, Simpson index. Results of two sites were statistically compared. The multivariate analysis was used to evaluate the response of plant species to exclosure and grazing conditions. In general, 47 and 41 species were identified respectively in exclosure and grazing regions having 28 of species in common. Results also showed that 19 and 13 species are unique to the exclosure and control area, respectively. As the results of the statistical comparison it is concluded the exclosure area has a significantly higher diversity and richness than the grazing area, but there is no significant difference in uniformity (evenness) between the two regions. Rényi entropy profile showed that the exclosure area where the alpha values is higher than one, has higher diversity than the grazing area. There is no significant difference between the canopy cover percentage of different vegetation groups in these two regions, but the exclosure area has a higher rate of overall plant cover percentage. Results of this study suggest the expansion of the exclosure areas with drill seeding using medical plants and valuable indigenous species, such as Ferula assa-foetida L., also systematic grazing program is proposed in the studied area.
Hamed Farzi, Reza Tamartash, Zeynab Jafarian, Mohamadreza Tatian,
Volume 14, Issue 1 (4-2020)
Abstract
The changes in the richness and plan’s tdiversity are of the signs of ecosystems manipulation. The more diverse the ecosystem is, the greater its resistance to degradation. Regarding the importance of this issue, this research was conducted in Arangeh rangelands located at the southern hills of Alborz. Investigate of the changes in species diversity and functional diversity of vegetation under different biological situation was the goal of the study. Data collected from five sites under different biological circumstances namely, seeding, pit seeding, exclosures, grazing management and natural rangeland. Indices of species diversity including: richness (S), Shannon (H), evenness (E) and Simpson (D) and the functional diversity index (convex hull hyper-volume (CHull), Functional Richness (FRic), Functional Evenness (FEve), Functional divergence (FDive) and index Rao (Rao) were calculated for all sites. FD package and generalized canonical discriminant analysis (gCCA) were used in R 3.1.1to calculate these indices and determine the effect of grazing intensity on diversity indices. In addition, Duncan's test was used to compare the means of grazing intensities. The results of the mean comparison indicated that the natural rangeland has the highest Shannon index and has a significant difference with the exclosure site. There was no significant difference in seeding sites and natural rangeland in terms of richness index. For other measures such as cluster analysis there was significant difference at (p< 0.05). The results of analysis of variance for different performance variables indicated that among functional diversity indices, except for the (CHull), functional richness indicators (FRic), functional divergence (FDiv) and evenness (FEve) showed a significant response to biological measures. The results of the mean comparison showed that Rao index had the highest value in the exclosure.
Behnaz Attaeian, Farhad Karami, Davoud Akhzari, Godarz Kiani,
Volume 17, Issue 2 (9-2023)
Abstract
Background and Objectives: The impact of grazing on the carbon cycle in mountain rangelands depends on various factors, including management practices and environmental conditions. However, the effects of grazing on carbon stocks remain uncertain due to challenges in tracking small changes in rangeland carbon stocks, lack of baseline information, and limited long-term grazing management data. This study aims to investigate the relationships between plant and soil parameters and organic carbon storage in a 10-year-old exclosure in the mountain rangelands of Asadabad, Hamadan.
Methodology: Two study sites, one under grazing and the other under a 10-year-old exclosure, were selected in a manner that minimized the gradient effect of ecological and biological factors. Vegetation and topsoil samples were collected along two 100-meter transects at 20-meter intervals, resulting in a total of 10 plots in each area. Vegetation parameters, including percentage cover, diversity (Simpson index), evenness (Shannon-Wiener index), and richness (Margaluf index), were calculated using Past 4.03 software. Soil organic carbon, phosphorus, potassium, and nitrogen were measured. Statistical analysis was performed using SAS V.4.1 software, and the distribution of variables was analyzed using principal component analysis (PCA) in Canoco 5 software.
Results: The findings revealed higher vegetation cover and plant diversity (richness and evenness) in the exclosure area. The vegetation cover percentage and species count in the grazing area were 35.1% and 127, respectively, while in the exclosure area, they were 67.6% and 139. The carbon stocks in vegetation and soil were significantly higher in the exclosure area, with values of 83.13 and 74.35 ton/ha in the soil surface, and 0.00219 and 0.00273 ton/ha, respectively (p < 0.05). The exclosure area exhibited a significant increase in Simpson diversity index (13.83) compared to the grazed area (12.63). Additionally, the Margaluf richness index showed a significant increase in the exclosure area. Soil phosphorus, potassium, and nitrogen nutrient measurements indicated an increase of 51%, 25.7%, and 15% in the exclosure area (p < 0.05). Correlation analysis revealed a significant linear relationship between organic carbon and phosphorus (r = 0.55) and nitrogen (r = 0.80) (p < 0.05). However, no significant correlation was observed between plant diversity indices and vegetation organic carbon storage.
Conclusion: The study demonstrated the positive impact of long-term exclosure on soil and vegetation parameters in mountain rangelands (p < 0.05). Exclosure not only enhanced plant and soil organic carbon storage but also resulted in increased soil nutrient levels, vegetation cover, and diversity and richness indices. The significant increase in plant diversity highlights the suitability of the Simpson index for evaluating diversity in mountain rangelands. However, the lack of a significant linear relationship between diversity index and organic carbon stocks in plants and soils suggests that factors other than plant diversity directly influence carbon stocks in mountain ecosystems.
