M.J. Roosta; K. Enayati; S.M. Soleimanpour; K. Kamali
Abstract
Introduction: Carbon sequestration (CS) by forests, pastures, afforested stands and soils is the most appropriate way to reduce atmospheric carbon. A combination of all these activities can help balance the global warming process by reducing the concentration of atmospheric CO2. The amount of CS and ...
Read More
Introduction: Carbon sequestration (CS) by forests, pastures, afforested stands and soils is the most appropriate way to reduce atmospheric carbon. A combination of all these activities can help balance the global warming process by reducing the concentration of atmospheric CO2. The amount of CS and quality of carbon storage in the soil depends on the interaction between climate, soil, tree species, litter chemical composition and their management. The results of Dinakaran and Krishnayya (2008) research showed that the type of vegetation cover has a significant effect on soil carbon storage. So that the amount of carbon storage in the soil depends on the amount of carbon entering the soil through plant debris and carbon loss through decomposition. To increase carbon in the soil, management activities such as increasing the amount of carbon entering the soil by adding litter and crop residues as well as reducing the rate of decomposition of soil organic matter should be done. Decomposition rate of soil organic matter is affected by soil condition (humidity, temperature and access to oxygen), sequestration of organic matter, placement of organic matter in the soil profile and the degree of physical protection by aggregates. Evaluating the role of aquifer management in reducing via storing the atmospheric CO2, to organic carbon (O.C) is the aim of this study. Materials and Methods: The studied land uses were as follows: 1-Rangeland-without flood spreading-with grazing (control), 2- Range without grazing-without flood spreading, 3- Six rangelands stripes-with grazing-with flood spreading, 4- Rangeland-Atriplex plantation-with spreading of flood, 5- Eucalyptus control forest-without flood spreading, 6- Eucalyptus forest-first strip-with flood spreading-BisheZard 4 (BZ4), 7- Eucalyptus forest-second strip-with flood spreading-(BZ4), 8- Eucalyptus forest-third strip-with flood spreading-(BZ4), 9- Acacia forest-with flood spreading-(BZ4). Soil and plant were sampled from each land use type. Then, the amount of O.C was measured in the laboratory and CS was calculated. The economic-environmental value of carbon stored in the soil is based on Rivers' proposal, which declares a carbon tax rate of $200 per tonne of CO2. The dollar is equal to 42,000 Iranian rials. Data were analyzed using randomized complete block design and Duncan test (at p < 0.05 ) was used to compare mean values using the SAS software. Results and Discussion: The analysis of variance showed that the effect of different land uses on the bulk density (BD), %O.C and the CS in the soil was significant at the level of 1%. Comparison of the mean of BD in various land uses showed that the eucalyptus forest (third strip) had the lowest BD compared to others, and the difference between this land use and other land uses was statistically significant. The first strip of Eucalyptus forest had the highest %O.C and the highest amount of CS in the soil, and the statistical difference between these two indices in this land use with other land uses was significant. Among the studied land uses, the lowest amounts of CS were related to the control range and range without grazing-without flood spreading. The interaction of plant to plant species on plant dry weight and plant carbon storage showed that the rangeland species of Heliantemum lippii and Dendrostellera lessertii in the range with flood spreading have the highest dry-weight and the species of Helianthomus has the highest amount of carbon storage. This indicates that the impacts of flood spreading on plant biomass production and carbon storage have been greater than the impact of no grazing on these indicators. In all uses, Artemisia sieberi showed the lowest dry weight and carbon storage. Planting of Eucalyptus camaldulensis irrigated with flood water spreading increased the soil O.C from 0.51% in the control to 1.68% in the first strip of eucalyptus forest (3.29 times). By calculating the mean of the three strips in which the eucalyptus was planted, it was found that the highest carbon content of 121.84 ton/ha was stored in the plant, litter and soil of this land use. Given that, each tonne of carbon is equivalent to 3.67 tons of CO2 gas, it can be concluded that 447.15 tonnes of CO2 gas from the air is stored as organic matter. The economic-environmental value of this CS is 3.76 billion rials ($89523.81) per hectare. Conclusion: The studied land that was irrigated with flood spreading, especially the eucalyptus forested area at Kowsar station, captured significant amounts of CO2 from the air and stored it as organic matter in the root and shoot of plants and in the soil. Also, this may lead to the release of a large amount of oxygen gas to the environment which play an important role in reducing air pollution. Considering the economic-environmental value of the carbon stored in the eucalyptus plantation forest areas, the development of this method in flood prone areas is quite economically justifiable. Due to the high potential of tree species in improving soil carbon storage, it seems that increasing the percentage of woody species and their physiological diversity have increased the carbon storage capacity of these species. Therefore, in order to improve the carbon storage capacity of flood distribution systems, it is suggested that the planting of native and perennial compatible species in these systems should be considered.
H. Rezaei; A.A. Jafarzadeh; A. Alijanpour; F. Shahbazi; Kh. Valizadeh Kamran
Abstract
Introduction: According to important ecological roles of soil organic matter in stabilizing ecosystems, it is essential to consider soil organic carbon condition for managements of worldwide problems such as soil quality, carbon cycle and climate change. Also, organic matter is one of the main ...
Read More
Introduction: According to important ecological roles of soil organic matter in stabilizing ecosystems, it is essential to consider soil organic carbon condition for managements of worldwide problems such as soil quality, carbon cycle and climate change. Also, organic matter is one of the main component of soil which have vital impress on its evolution. Therefore, assessing soil organic matter fate in various environmental conditions and its relation with environmental factors will be useful for management decisions. Determining soil organic carbon content, stocks and forms by the physico-chemical and micromorphological studies may respond to the question about soil organic matter evolution from the different point of views. Based on mentioned reasons, our research work focused on soil organic matter content, stocks and forms under various environmental condition of the forest ecosystem to find new aspects of its relation with environmental factors.
Material and Methods: This research work was carried out in Arasbaran forest, northwest of Iran, which recognized as a part of the international network of biosphere reserves and has unique species of plants with special ecological properties. Sampling was carried out in a Kaleybar Chai Sofla sub-basin as a part of Arasbaran forest with eastern longitude of 46º 39´ to 46º 52´ and northern latitude of 38º 52´ to 39º 04´. Based on the Amberje climate classification, the climate of the region is semi-humid and moderate. The soil moisture and temperature regimes are Xeric and Mesic, respectively. Hornbeam (Carpinus betulus) and Oak (Quercus petraea and Quercus macranthera) were identified as the main woody species in this area and volcano-sedimentary rocks were the geological structure. Primary site surveying showed 5 forest stand types such as Oak (Quercus macranthera), Hornbeam-Oak (Carpinus betulus-Quercus macranthera), Hornbeam (Carpinus betulus), Hornbeam-Oak (Carpinus betulus-Quercus petraea), Oak (Quercus petraea) along altitudinal transects, that used as environmental parts with different conditions. In each environmental part, a soil profile was described and sampling was done for physical, chemical and micromorphological analysis. After preparing soil samples in the laboratory, soil physico-chemical routine analyses were carried out by standard methods and then the studied soils were classified on the basis of 12th edition of soil taxonomy. To achieve the main aim of the study, various aspects of soil organic matter evolution were assessed. Soil organic matter content was determined according to the Walkley–Black wet oxidation method and using alteration factor f = 1.724 recommended by USDA. Variance analysis and means compare of soil organic matter content in surface horizons of different environmental parts were performed by using the SPSS software package and Dunkan's multiple range test, respectively. Soil organic carbon stocks were calculated for each soil horizon and weighted average based on profile depth was used to calculate this index for each soil profile. The prepared thin section for micromorphological study was examined under both plane-polarized light (PPL) and cross-polarized light (XPL) using a polarized microscope and explained based on standard terminology to identify various forms of soil organic matter all over the study area.
Results and Discussion: Results revealed increasing of soil evolution with decreasing of elevation. Entisols, Inceptisols, Alfisols and Mollisols with different families were the soil observed along altitudinal transects by decreasing elevation. According to the obtained results, environmental effects caused different soil organic matter content and evolution with various soil organic carbon stocks in each part. Improvement of environmental condition by decreasing elevation resulted in more evolution of soil organic matter, dominant of decomposed forms of organic matter and rise of soil organic carbon stocks from the highest part to the lowest one. Soil organic matter content in soil surface increased by elevation, although the main source of soil organic matter have better condition in lower parts due to ecological reasons. This inverse statue can be explained by special environmental conditions causing limited organic remnants decomposition in the highest parts. In the same trend with soil evolution, soil organic carbon stocks increased by decreasing of elevation. This trend refers to the relation of mentioned index ability with various soil-forming processes. Micromorphological study showed that organic intact remnants were the dominant forms in upper parts which changed to well-decomposed forms in the lowest parts. This observation revealed the occurrence of mechanical decomposition processes of organic remnants in high elevation while biochemical ones happen in the lower parts. Also, this distribution of soil organic matter decomposition processes can explain soil organic carbon content and stocks all over the study area.
Conclusion: Elevation was identified as an important environmental factor controlling soil organic matter in the studied scale. Generally, results confirm the same trend for soil organic matter evolution and soil organic carbon stocks with soil development, especially in pedogenesis processes in relation to organic matter. Thus, it can be recommended to use soil map for management of soil organic matter under various environmental conditions in large-scale studies.
