Parviz Gholami; Mohammad Farzam; Nateq Lashkari sanami; Lale Amouzgar
Abstract
The study of soil seed bank provides vital information for rehabilitation and restoration of rangeland ecosystem. In the arid and semi-arid environments, shrub plants may cause accumulation of seed bank under their canopy, thereby protecting them against the livestock herbivory and the other environmental ...
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The study of soil seed bank provides vital information for rehabilitation and restoration of rangeland ecosystem. In the arid and semi-arid environments, shrub plants may cause accumulation of seed bank under their canopy, thereby protecting them against the livestock herbivory and the other environmental factors. This study was conducted with objective to investigate effect of Astragalus brachycalyx on composition of soil seeds bank, in two area of enclosure and under grazing. For this purpose, sampling of soil seed bank under the canopy of this species and its open space adjacent was measured using a flexible plot along the 100 meters transect. Soils were sampled from 0-5 and 5-10 cm depths. Then seed bank composition was identified after seed germination in glasshouse. The results showed that 16 species under the canopy of Astragalus brachycalyx and 12 plant species in the open space adjacent in enclosure area and 21 species under the canopy of Astragalus brachycalyx and 11 plant species in the open space adjacent in under grazing area. In the soil seed bank of an area under the livestock grazing and understory of Astragalus brachycalyx, the species namely Silene longipetala, Mentha longifolia, Veronica anagallis-aquatica and Anthemis odontostephana had the greatest numbers of seeds respectively. The area under livestock grazing had higher density of seed bank of plants with annual and perennial life, Therophytes and Hemicryptophytes biological forms, annual and perennial vegetative forms of forbs, and palatable classes II and III in understory compared to the open space.
Alirostam Khanizadeh; Reza Erfanzadeh; Reza Siahmansur
Abstract
The aim of this study was to quantify the response of Bromus tomentellus, Hordeum bulbosum and Agropyron trichophorum to continuous grazing of sheep in semi-arid rangelands of Lorestan. In two areas, grazed and ungrazed, 4 transects of 200 meters were established and 10 random points were selected along ...
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The aim of this study was to quantify the response of Bromus tomentellus, Hordeum bulbosum and Agropyron trichophorum to continuous grazing of sheep in semi-arid rangelands of Lorestan. In two areas, grazed and ungrazed, 4 transects of 200 meters were established and 10 random points were selected along of each transect and at each point the nearest plant considered for further study. Morphological traits of each selected plant were measured i.e. height, internode distance, root length, root weight, production and mass. After reviewing the data normalization, the averages between grazed and ungrazed were compared by non-paired t-test. The effect of livestock grazing on height, shoot internode, length and root weight, biomass and yield of H. bulbosum and A. trichophorum were significant. The mean weight of H. bulbosum in the ungrazed and grazed areas was 117.1 gr and 16.1 gr, respectively, and the height of A. trichophorum was 525.1 mm in the ungrazed and 334.7 mm in the grazed areas, respectively. Grazing of livestock had no significant effect on the height and internode distance of B. tomentellus (p>0.05). Animal grazing significantly increased root length of 58.35 mm in B. tomentellus. In general, the results of this study showed that different species of plants exposed different reactions and trade-off against grazing depending on the type of plant species. Knowledge about of the morphological changes of plant species against grazing can greatly help us for the management of sustainable grazing in the rangelands.
Reza midipour; Reza Erfanzadeh; Marzban Faramarzi
Abstract
Intensive livestock grazing is one of the most important destructive factors in rangelands that leads to decrease of diversity and causes disappearance of sensitive plants. On the other hand, considering the scales in assessment of diversity is very importance to study the variability of plant diversity ...
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Intensive livestock grazing is one of the most important destructive factors in rangelands that leads to decrease of diversity and causes disappearance of sensitive plants. On the other hand, considering the scales in assessment of diversity is very importance to study the variability of plant diversity patterns in different scales. Therefore, current study aimed to investigate the impact of livestock grazing on diversity components in different scales using additive partitioning methods in western country rangelands in the Ilam province. Sampling was carried out in 40 plots of 4m2 in 8 rangeland sites including 4 exclosures and 4 grazing sites. Based on additive partitioning diversity methods, the total diversity was partitioned into additively components within and among samples. The results showed that diversity among sites (β2) had the highest contribution of total diversity that indicated the importance of this scale for conservation practices, and it was due to the variation of composition between sites. In addition, the results represented that exclosure in the semi-arid areas can increase diversity at plot scale, while in the regional scales (diversity among sites or β2) livestock grazing leads to increase in diversity. Therefore, exclosure of rangelands does not necessarily lead to increase in diversity. Also, long terms exclosure can lead to increase evenness that resulting in increasing competition among plants, therefore it could decrease plant diversity.
zahra nikbakht; Mohammad Farzam; Mohammad Khajeh Hosseini; Hamid Ejtehadi
Abstract
The study of soil seed bank provides useful information on management and restoration of natural ecosystems. In the arid environments, some perennial plants may cause accumulation of seed bank under their canopy, thereby protecting them against the livestock herbivory and the other environmental factors. ...
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The study of soil seed bank provides useful information on management and restoration of natural ecosystems. In the arid environments, some perennial plants may cause accumulation of seed bank under their canopy, thereby protecting them against the livestock herbivory and the other environmental factors. This study was conducted with objective to investigate effect of perennial plants on density of soil seeds bank, under different utilization levels in an arid steppe rangeland. Three adjacent rangeland sites were selected, i.e. intense grazing, moderate grazing and no grazing (enclosure), and three line transects were randomly located within each site. Along each transect, soil samples were taken from the depth of 0–5 cm under the canopy of perennial plants or the nearby open space. The seed bank density was determined by the technique for separating seeds from the soil. The density of soil seed bank in the moderate and intensive grazing sites was higher than in the enclosure. In addition, seed bank density under the canopy of perennial plants was significantly higher than in open space, in each of three sites. The highest and lowest seed bank density were observed under the canopy of Rosa persica and Astragalus heratensis, respectively. Generally, the results of this research indicate the key role of perennial range plants in protecting soil seed bank of other plants, under the circumstances of high livestock grazing in the arid steppe rangelands.
Javad Motamedi; Esmaeil Sheidai Karkaj
Abstract
Species diversity is one of the important characteristics shows rangeland ecosystems changes, which isalready under effects of management practices. Thus, this research was conducted to study speciesdiversity variation and assess suitable distributive abundance model in three rangeland sites in WestAzerbaijan. ...
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Species diversity is one of the important characteristics shows rangeland ecosystems changes, which isalready under effects of management practices. Thus, this research was conducted to study speciesdiversity variation and assess suitable distributive abundance model in three rangeland sites in WestAzerbaijan. These sites were almost similar in environmental properties and differ in view point ofgrazing intensity (light, moderate and heavy intensities). After selecting sampling areas in each of thesites, species cover were recorded in 60, one square meter quadrates with 10 meter far from each otherwhich established along 100 meter transects in sites and then richness, evenness and diversity(heterogeneity) indices were calculated. Thus, rank-abundance curves were plotted and fourdistribution models such as log-normal, geometric, log-series and Brocken stick were fitted to each ofthese sites and then best model was selected in 0.05 level of confidence. Means comparison testshowed that richness, evenness and heterogeneity indices have significant differences (P<0.01) insites. Highest diversity is observed in the light grazing intensity site and lowest diversity is in heavygrazing intensity site. Species rank-abundance curves point out that low-abundance species are seenlower in light grazing site and its curve have gentler slope than moderate and high grazing intensitysites thus its diversity is higher. There is lowest species number in high grazing intensity site andevenness is lowest too due to its high number of rare and dominant species. Log-normal model wasfitted to light site implying on sustainable community and high grazing intensity site is fitted withgeometric model which point out on distractive communities with low diversity. Overall resultsshowed that implementing light grazing can protect species diversity and heavy intensity declinesspecies diversity that this shows the need considering of management on implementing light grazingintensity in the rangeland.
