Mehri Dinarvand; Seyed Bahram Andarzian; Hamid Ejtehadi; Mohammad Farzam
Volume 25, Issue 2 , August 2018, , Pages 388-398
Abstract
Modeling the growth stages of plant species and its relation with environmental factors, especially climatic and edaphic changes, can lead to appropriate management and conservation plans for rangeland rehabilitation and improvement. The objectives of this study were to evaluate the ...
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Modeling the growth stages of plant species and its relation with environmental factors, especially climatic and edaphic changes, can lead to appropriate management and conservation plans for rangeland rehabilitation and improvement. The objectives of this study were to evaluate the AquaCrop model for two species (Medicago polymorpha L., Hordeum murinum subsp. glaucum (Staud.)Tzvelev) in the Shimbar protected area. Therefore, model evaluation was performed based on the data recorded during 2013-2015. Coefficient of determination (R2), absolute and normalized root mean square error (RMSE, NRMSE), Willmott agreement index (d) and Efficiency Coefficient (EF) were used to compare the simulated data with the data of the second year. The evaluation of AquaCrop model for canopy cover and biomass in selected species demonstrated that the model had the necessary efficiency for simulation. The values of R2, EF, and, d recorded for the canopy cover and biomass of Medicago polymorpha and Hordeum murinum subsp. glaucum were near 1. The values of RMSE calculated for canopy cover and biomass were between 1 to 3.7 and 0.03 to 0.23, respectively.
Fatemeh Salarian; Jamshid Ghorbani; Nosrat Allah Safaeian
Volume 20, Issue 1 , June 2013, , Pages 115-129
Abstract
Grazing animals affect rangeland vegetation structure and function directly and indirectly. These effects can be assessed in exclosures. In this study, the vegetation composition and some vegetation indices (functional groups, biomass, species diversity and richness) were compared in an exclosure (livestock ...
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Grazing animals affect rangeland vegetation structure and function directly and indirectly. These effects can be assessed in exclosures. In this study, the vegetation composition and some vegetation indices (functional groups, biomass, species diversity and richness) were compared in an exclosure (livestock excluded for about 10 years) and grazed areas in Chahar Bagh rangeland in Golestan province. The percentage of canopy cover, stone and gravel, bare ground, litter and the biomass were estimated in quadrates of 1 m2. Results showed that there were 34 species common in both areas while 7 and 11 species were restricted to exclosure and grazed areas, respectively. Results of t-test showed that exclosure significantly increased the percentage of canopy cover of some desirable species such as Agropyron intermedium, A. trichophorum, Festuca ovina. Also, the percentage of canopy cover of hemicryptophyte, grasses, forbs, and perennials significantly increased in exclosure area. Moreover, Simpson diversity index and species number significantly increased in exclosure. The biomass of grasses and total biomass also significantly increased from grazed area to exclosure. According to the results, exclosure for less than ten years could cause some changes in vegetation of this rangeland.
Majid Mohammad-Esmaeili; Reza Kavandi; Vahid Karimian; Hossein Sabouri
Volume 19, Issue 4 , March 2013, , Pages 703-713
Abstract
Grazing and harvesting are two major ways of utilizing natural and artificial grasslands. Current research was aimed at studying the effects of shoot cutting frequency on total phytomass, above-ground phytomass, underground phytomass, the condition of tillering, and the tolerance of four halophytes (P. ...
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Grazing and harvesting are two major ways of utilizing natural and artificial grasslands. Current research was aimed at studying the effects of shoot cutting frequency on total phytomass, above-ground phytomass, underground phytomass, the condition of tillering, and the tolerance of four halophytes (P. distans, A. littoralis, A. lagopoides and J. articulates) against cutting. This experiment was carried out in a completely randomized design with 7 replications. Four mentioned species and four different cuttings were considered as treatments. Seedlings of four species in growth stage were collected from grasslands of Inchebroon, located in north of Agh-ghala, and were cultivated in the pots. During the growth period, aerial parts of the species were cut at 6 cm above the soil surface of pots in four cutting treatments including once every week, once every two weeks, once every four weeks, and control treatment. Results indicated that total phytomass, above- ground phytomass and underground phytomass of A. littoralis, A. lagopoides and J. maritimus reduced as a response to the stress of cutting compared with control treatment. Consequently, these three species cannot retrieve total phytomass in comparison with control treatment. Total phytomass of P. distans remained stable in all treatments; therefore this species is able to retrieve phytomass loss completely. Repeating cutting decreased the number of shoots in four species. According to the results, in one-year experimental conditions, P. distans was identified as a high-tolerant species against cutting while A. littoralis, A. lagopoides and J. maritimus showed a medium tolerance.
Noor ... Abdi; Hasan Madah arefi; Ghava din Zahedi amiri
Volume 15, Issue 2 , January 2008, , Pages 269-282
Abstract
Atmospheric carbon dioxide concentrations have substantially increased in recent decades. Land management practices, however, offer opportunities to mitigate the rise in atmospheric CO2 concentration through sequestration of this additional carbon via storage in plant biomass and soil organic matter ...
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Atmospheric carbon dioxide concentrations have substantially increased in recent decades. Land management practices, however, offer opportunities to mitigate the rise in atmospheric CO2 concentration through sequestration of this additional carbon via storage in plant biomass and soil organic matter in a process termed terrestrial C sequestration. Rangelands ecosystems have a large potential to sequester C because they occupy about half of the world's land area. In Iran, the Astragalus rangelands with about 17 million hectare area have 10% of the country land area and have the important role in carbon sequestration. In order to investigation the role and potential of Astragalus rangelands in carbon sequestration, a study was carried out at a key area of Astragalus verus-Bromus tomentellus vegetation type in Malmir rangeland site, Shazand township of Markazi province and the content of aboveground and underground biomass carbon, litter carbon and soil organic carbon was determined. The results showed that the total carbon sequestration per hectare was 32.95 ton and 87.43 % of total carbon sequestration was soil organic carbon. The results of biomass carbon distribution showed that the carbon content in aerial biomass was higher than underground biomass. Correlation and stepwise regression analysis revealed that the content of carbon sequestration was positively related to Astragalus height and volume, aerial and underground biomass, total biomass, litter amount and soil organic carbon (SOC) content. It was concluded that the Astragalus rangelands have a large potential to sequester carbon and the soil is most important sink for organic carbon storage in this rangelands
Faez Raeisi Kahrouie; Jahangard Mohammadi; Esmaiel Asadi
Volume 9, Issue 3 , September 2001, , Pages 991-1004