شبیه‏سازی دینامیک کربن آلی خاک تحت تأثیر سناریوهای مختلف فرسایش آبی و مدیریت چرا در مراتع نیمه‏خشک باجگاه با استفاده از مدل Century

نوع مقاله : مقاله کامل علمی پژوهشی

نویسندگان

1 دانش دانشجوی دکتری گروه احیاء مناطق خشک و کوهستانی، دانشگاه تهران، آموخته کارشناسیارشد مدیریت مناطق بیابانی، بخش مهندسی منابع طبیعی و محیطزیست، دانشگاه شیراز

2 استادیار بخش مهندسی منابع طبیعی و محیطزیست، دانشگاه شیراز

چکیده

سابقه و هدف: بیشتر مطالعات یک ارتباط قوی بین فرسایش آبی و هدر‏روی کربن آلی خاک را گزارش کرده‏اند، به طوری که جابجایی و تغییر مکان کربن ناشی از فرسایش آبی یک فاکتور مهم تأثیر گذار بر غلظت CO2 در اتمسفر بیان شده است. بنابراین فهمیدن اثر فرآیند فرسایش آبی بر کربن آلی خاک اکوسیستم ضروری است. با توجه به اینکه ارزیابی اثرات فرسایش آبی بر ذخیره کربن آلی خاک در طولانی مدت بدون ابزار مدل‏سازی مشکل هست، مطالعه دینامیک کربن آلی خاک از طریق استفاده از مدل‏های شبیه‏سازی در ترکیب با داده‏های اندازه‏گیری شده توصیه شده است. با توجه به اینکه مراتع ایران مساحت بزرگی از کشور را فراگرفته، مدل‌سازی اثر فرسایش آبی بر دینامیک کربن آلی خاک در مراتع می‌تواند راهکارهای مدیریتی شایسته‌ای در اختیار سازمان‌های مرتبط قرار دهد. تاکنون در ایران مدل‌سازی کربن آلی خاک تحت تأثیر فرسایش آبی انجام نشده است و این بررسی می‌تواند زیربنای آینده مدل‌سازی کربن آلی خاک باشد. بنابراین تحقیق حاضر با هدف 1) بهبود اعتبارسنجی مدل Century به عنوان پرکاربردترین مدل در مطالعات کربن خاک با استفاده از خروجی سه مدل فرسایش آبی GLEAMS، WEPP و ANSWERS و 2) شبیه‏سازی دینامیک ذخیره کربن آلی خاک تحت تأثیر دو سناریو فرسایشی در مراتع نیمه خشک باجگاه انجام گرفت.
مواد و روش‏ها: برای انجام این تحقیق تعداد 60 نمونه خاک به روش نمونه‏برداری تصادفی از عمق 20-0 سانتی‏متری از سطح مراتع نیمه خشک باجگاه برداشت شد. جهت تعیین وزن مخصوص ظاهری خاک دو نمونه سیلندر در کنار هر گودال خاک (به طورکلی 120 نمونه) برداشته شد. پس از تعیین حجم نمونه‏گیری پوشش گیاهی (تعداد پلات)؛ بیومس بالازمینی، لاشبرگ و بیومس زیرزمینی موجود در 17 پلات جمع‏آوری و به آزمایشگاه منتقل شدند. ببا استفاده از 43 سال داده‏های هواشناسی ایستگاه هواشناسی، داده‏های ویژه سایت و همچنین مقادیر پارامترهای فیزیولوژیکی و اکولوژیکی مرتع، پارامتریابی و کالیبره کردن مدل Century انجام شد. سپس میانگین میزان دراز مدت فرسایش آبی شبیه‏سازی شده توسط سه مدل‏ فرسایشی WEPP، GLEAMS و ANSWERS به عنوان ورودی در مدل وارد گردیدند. در نهایت یک مدل فرسایش آبی که میزان فرسایش شبیه‏سازی شده توسط آن موجب بهبود نتایج اعتبارسنجی مدل Century شد، انتخاب گردید و سپس اثر دو سناریو فرسایش آبی بر تغییرات کربن آلی خاک برای دو دوره مدیریت چرای دام مورد بررسی قرار گرفت.
یافته‏ها: نتایج شبیه‏سازی نشان داد که استفاده از خروجی مدل GLEAMS باعث شده که مدل Century، ذخیره کربن آلی خاک را به طور دقیق‏تری پیش‏بینی کند. بنابراین از خروجی مدل فرسایشی GLEAMS برای شبیه‏سازی تغییرات ذخیره کربن آلی خاک تحت تأثیر فرسایش آبی داستفاده شد. نتایج شبیه‏سازی‏های مدل Century نشان داد که ذخیره کربن آلی خاک در مراتع باجگاه طی دوره II با مدیریت چرای متوسط دام از 3496 تا 93/3260 (گرم بر سانتی‏مترمربع) و از 3496 تا 90/3243 به ترتیب در سناریوهای بدون فرسایش و فرسایش کاهش یافته است و تفاوت معنی‏داری (05/0 p <) بین آنها مشاهده نشد. همچنین طی دوره III با مدیریت بدون چرای دام، ذخیره کربن آلی خاک از 30/3245 تا 04/3356 (گرم بر سانتی‏مترمربع) و از 37/3227 تا 42/3350 به ترتیب در سناریوهای بدون فرسایش و فرسایش کاهش یافته بود. به طورکلی فرسایش آبی ذخیره کربن آلی خاک را در مراتع نیمه‏خشک باجگاه در مقایسه با سناریو بدون فرسایش به ترتیب به میزان 52/0 درصد و 16/0 درصد در پایان دوره‏های II و III کاهش داده بود. فرسایش موجب کاهش ناچیز ذخیره کربن آلی خاک در مراتع نیمه‏خشک باجگاه در مقایسه با سناریو بدون فرسایش شده بود. برمبنای نتایج این مطالعه می‏توان گفت نقش مدیریت چرای دام در مراتع نیمه‏خشک باجگاه بیشتر از فرسایش در هدرروی و تغییرات ذخیره کربن آلی خاک مشهود بوده است.

کلیدواژه‌ها


عنوان مقاله [English]

Simulating soil organic carbon dynamics as affected by different water erosion scenarios and grazing management in semi-arid rangelands of Bajgah using the Century model

نویسندگان [English]

  • Bijan Azad 1
  • Sayed Fakhreddin Afzali 2
1 Shiraz University
2 Assistant prof. of Department of desert regions management, shiraz university
چکیده [English]

Background and Objectives: Most studies have reported a strong relationship between water erosion and soil organic carbon (SOC) losses, so that carbon displacement caused by water erosion stated as an important factor affecting the concentration of CO2 in the atmosphere. Therefore, understanding water erosion processes effect on SOC within an ecosystem is essential. Since evaluating the impacts of water erosion on SOC stock dynamic in long-term is difficult without modeling tool, studying of SOC dynamic through use of simulation models in combination with measured data is recommended. Considering that rangelands of Iran have taken a large part of the country, modeling the effect of water erosion on SOC dynamics in rangelands can provide appropriate management solutions for related organizations. The SOC modeling has not been conducted under the influence of water erosion, and this study could be basis for the future of SOC modeling. Therefore, the present study aims to: 1) improve the validation of the Century model as the most widely used model in the soil carbon studies, by using the output of three water erosion models of GLEAMS, WEPP, and ANSWERS, and 2) simulating the SOC stock dynamic under the influence of two erosion scenarios in the semi-arid rangelands of Bajgah.
Materials and Methods: To conduct this research, 60 soil samples were taken by randomized sampling methodfrom a depth of 0-20 cm of soil in the semi-arid rangelands of Bajgah. To determine the soil bulk density, two cylinders were collected beside each soil puddle (120 samples). After determining the volume of vegetation sampling (number of plots); aboveground biomass, litter and belowground biomass were collected in 17 plots then transferred to the laboratory. Parameterization and calibrating the Century model was performed by using 43 years of weather data, site specific data, as well as physiological and ecological parameters of rangeland. Then, the long-term average of water erosion rate simulated by WEPP, GLEAMS and ANSWERS erosion models entered as input in the Century model. Finally, a water erosion model, that its simulated erosion rate improves the validation results of the Century model, was selected then illustrated the effect of two water erosion scenarios on the changes of SOC stock for two periods of grazing management including period of nationalization of rangelands with moderate grazing management.
Results: The simulation results showed that use of the GLEAMS model output made the Century model more accurately predict SOC stock. Therefore, the GLEAMS erosion model output was used for simulate the SOC stock variations under the influence of water erosion. The simulation results of the Century model showed that the SOC stock in the Bajgah rangelands during the II period with moderate grazing management, decreased from 3496 to 3260.93 (g cm-2) and 3496 to 3243.90 (g cm-2) in the no-erosion and erosion scenarios, respectively and there was no significant difference between them (p < 0.05). Also during the III period with no grazing management, SOC stock decreased from 3245.30 to 3356.04 (g cm-2) and 3227.37 to 3350.42 (g cm-2) in the no-erosion and erosion scenarios, respectively and there was no significant difference between them (p <0.05). Generally, water erosion decreased the SOC stock in the semi-arid rangelands of Bajgah compared with the non-erosion scenario by 0.52% and 0.16% in the end of periods II and III, respectively. The erosion resulted in a slight reduction in SOC stock in the semi-arid rangelands of Bajgah compared to the non-erosion scenario. Based on the results of this study, it can be state that the role of grazing management than the erosion in the changes and losses of SOC stock was more evident in the semi-arid rangelands of Bajgah.

کلیدواژه‌ها [English]

  • Global Warming
  • carbon sequestration
  • Soil Organic Carbon Stock
  • Soil Carbon Modeling
  • Water Erosion Models
1.Abril, A., and Bucher, E.H. 2001. Overgrazing and soil carbon dynamics in the western Chaco of Argentina. Applied Soil Ecology. 16: 3. 243-249.
2.Abtahi, A., Karimiyan, N., and Solhi, M. 1987. Semi-detailed pedology studies reports Bajgah’s region- Province of Fars. Department of Soil Science, Semi-Detailed Report. College of Agriculture, Shiraz University, Shiraz University. 06.18.1991. (In Persian)
3.Afzali, S.F., Azad, B., Golabi, M.H.,and Francaviglia, R. 2019. Using RothC model to simulate soil organic carbon stocks under different climate change scenarios for the rangelands of the arid regions of southern Iran. Water.11: 10. 1-13.
4.Al-Rowaily, S.L., El-Bana, M.I.,Al-Bakre, D.A., Assaeed, A.M., Hegazy, A.K., and Ali, M.B. 2015. Effects of open grazing and livestock exclusion on floristic composition and diversity in natural ecosystem of Western Saudi Arabia. Saudi J. Biol. Sci. 22: 4. 430-437.
5.Azad, B., and Afzali, S.F. 2018. Modelling the impacts of climate change on the soil CO2 emissions in arid rangelands (southern Iran). Des. Ecosyst. Engin. Journal. 7: 20. 71-87. (In Persian)
6.Azad, B., and Afzali, S.F. 2019. Evaluation of two soil carbon models performance using measured data in semi-arid rangelands of Bajgah,Fars province. Iran. J. Soil Water Res.50: 4. 819-835. (In Persian) 
7.Bagheri, E. 2010. Estimation of runoff, erosion and sediment by wepp model case study: a study watershed in the western part of agricultural college of Shiraz and subbasin (Khosro-shirin) upstream of mollasadra dam watershed, fars province and comparison with results of mpsiac and answers models. M.Sc. thesis. College of Agriculture, University of Shiraz. (In Persian)
8.Birdsey, R., Heath, I.S., and Williams, D. 2000. Estimation of carbon budget model of the United States forest sector. P 51-59. In: Advances in terrestrial ecosystem carbon inventory, measurements, and monitoring conference in Raleigh, North Carolina, USA.
9.Blake, G.R., and Hartge, K.H. 1986.Bulk density. P 363-376, In: Methods of Soil Analysis. Part 1. Physical and Mineralogical Methods; Soil Science Society of America, American Society of Agronomy: Madison, WI, USA.
10.Borrelliet, P., Paustian, K., Panagos,P., Jones, A., Schütt, B., and Lugato,O. 2016. Effect of good agricultural and environmental conditions on erosion and soil organic carbon balance: A national case study. Land Use Policy. 50: 408-421.
11.Bouyoucos, G.J. 1962. Hydrometer method improved for making particle size analysis of soils. Agron. J.56: 464-465.
12.Cao, J., Wang, X., Sun, X., Zhang, L., and Tian, Y. 2013. Effects of grazing intensity on soil labile organic carbon fractions in a desert steppe area in Inner Mongolia. Springer Plus. 2: 1. 1-8.
13.Chen, Y., Li, Y., Zhao, X., Awada, T., Shang, W., and Han, J. 2012. Effects of grazing exclusion on soil properties and on ecosystem carbon and nitrogen storage in a sandy rangeland of Inner Mongolia, Northern China. Environmental Management. 50: 622-632.
14.Derner, J., and Schuman, G. 2007. Carbon sequestration and rangelands: a synthesis of land management and precipitation effects. J. Soil Water Cons. 62: 2. 77-85.
 15.Derner, J.D., Boutton, T.W., and Briske, D.D. 2006. Grazing and ecosystem carbon storage in the North American Great Plains. Plant and Soil. 280: 1. 77-90.
16.Eller, B.H., and Bettany, J.R. 1995. Calculation of organic matter and nutrients stored in soils under contrasting management regimes. Can. J. Soil Sci. 75: 529-538.17.Faghihinia, M., and Afzali, S.F.2013. Effects of wind erosion on
soil organic carbon dynamics and other soil properties: Dejgah catchment, Farashband County, Shiraz Province, Iran. Afric. J. Agric. Res. 8: 4452-4459.
18.Golluscio, R., Austin, A., Martinez, G., Gonzalez, P.M., Sala, O., and Jackson, R. 2009. Sheep grazing decreases carbon and nitrogen pools in the Patagonian Steppe: combination of direct and indirect effects. Ecosystems. 12: 686-697.
19.Harden, J., Sharpe, J., Parton, W., Ojima, D., Fries, T., Huntington, T., and Dabney, S. 1999. Dynamic replacement and loss of soil carbon on eroding cropland. Global Biogeochemical Cycles. 13: 885-901.
20.Jafari, M., Azarnivand, H., Sadeghipour, A., Kamali, N., Heidari, A., and Maddah arefi, H. 2016. Effect of Different Grazing Intensities on Soil Carbon Sequestration and Nitrogen Stabilization (Case Study: Shahriar). J. Range Water. Manage. 69: 2. 427-436. (In Persian)
21.Kamoni, P., Gicheru, P., Wokabi, S., Easter, M., Milne, E., Coleman, K., Falloon, P., Paustian, K., Killian, K., and Kihanda, F. 2007. Evaluation of two soil carbon models using two Kenyan long term experimental datasets. Agriculture, Ecosystems and Environment. 122: 95-104.
22.Khalily, A. 2008. Ecological regions of Iran-vegetation types of Shiraz area. Research Institute of Forests and Rangelands, Technical publication No. 390, 208p. (In Persian)
23.Kirk, P. L. 1950. Kjeldahl method for total nitrogen. Analytical Chemistry.22: 2. 354-358.
24.Lal, R. 2003. Soil erosion and the global carbon budget. Environment International. 29: 437-450.
25.Lal, R. 2004. Soil carbon sequestration to mitigate climate change. Geoderma. 123: 1-22.
26.Lal, R., and Pimentel, D. 2008. Soil erosion: a carbon sink or source? Science. 319: 1040-1042.
27.Li, Z., Liu, C., Dong, Y., Chang, X., Nie, X., Liu, L., Xiao, H., Lu, Y., and Zeng, G. 2017. Response of soil organic carbon and nitrogen stocks to soil erosion and land use types in the Loess hilly–gully region of China. Soil and Tillage Research. 166: 1-9.
28.Martinez-Mena, M., Lopez, J., Almagro, M., Boix-Fayos, C., and Albaladejo, J. 2008. Effect of water erosion and cultivation on the soil carbon stock in a semiarid area of South-East Spain. Soil and Tillage Research. 99: 119-129.
29.McSherry, M.E., and Ritchie, M.E. 2013. Effects of grazing on grassland soil carbon: a global review. Global Change Biology. 19: 1347-1357.
30.Momtahen, H. 1989. Testing the ANSWERS computer model for forecasting floods and estimating erosion from small agricultural watersheds. M.Sc. thesis. College of Agriculture, University of Shiraz.(In Persian)
31.Moosavi, S.A. 2011. Spatial changes and the impact of water quality on soil hydraulic properties and the development functions artificial transfer and neural networks to estimate it. PhD thesis. College of Agriculture,University of Shiraz. (In Persian)
32.Olson, K.R., Al-Kaisi, M., Lal, R., and Cihacek, L. 2016. Impact of soil erosion on soil organic carbon stocks. J. Soil Water Cons. 71: 3. 61-67.
33.Orgill, S.E., Condon, J.R., Conyers, M.K., Morris, S.G., Alcock, D.J., Murphy, B.W., and Greene, R.S.B. 2016. Removing grazing pressure from a native pasture decreases soil organic carbon in southern New South Wales, Australia. Land Degradation and Development. 29: 2. 274-283.
34.Papanastasis, V.P., Bautista, S., Chouvardas, D., Mantzanas, K., Papadimitriou, M., Mayor, A.G., Koukioumi, P., Papaioannou, A., and Vallejo, R.V. 2015. Comparative assessment of goods and services provided by grazing regulation and reforestation in degraded mediterranean rangelands. Land Degradation and Development. 28: 4. 1178-1187.
35.Parton, W.J., Schimel, D.S., Cole, C., and Ojima, D. 1987. Analysis of factors controlling soil organic matter levels in Great Plains grasslands. Soil Sci. Soc. Amer. J. 51: 1173-1179.
36.Pei, S., Fu, H., and Wan, C. 2008. Changes in soil properties and vegetation following exclosure and grazing in degraded Alxa desert steppe of Inner Mongolia, China. Agriculture, Ecosystems and Environment. 124: 33-39.
37.Piñeiro, G., Paruelo, J.M., Oesterheld, M., and Jobbágy, E.G. 2010. Pathways of grazing effects on soil organic carbon and nitrogen. Rangeland Ecology and Management. 63: 109-119.
38.Polyakov, V., and Lal, R. 2004. Modeling soil organic matter dynamics as affected by soil water erosion. Environment International. 30: 547-556.
39.Pournader, M., Ahmadi, H., Feiznia,S., Karimi, H., and Peirovan, H.R.2018. Spatial prediction of soil erosion susceptibility: an evaluation of the maximum entropy model. Earth Science Informatics. 11: 1-13.
40.Quinton, J.N., Govers, G., Van Oost,K., and Bardgett, R.D. 2010. The impact of agricultural soil erosion on  biogeochemical cycling. Nature Geoscience. 3: 311-314.
41.Riahi Samani, M., and Raiesi, F.2014. Soil Organic Carbon Dynamics in Native Rangelands Exposed to Grazing and Ungrazing Management in Rangeland Ecosystems of Central Zagrous. J. Water Soil. 28: 4. 742-753. (In Persian)
42.Ritchie, M.E. 2014. Plant compensation to grazing and soil carbon dynamics in a tropical grassland. Peer J. 2: e233.
43.Roose, E.J., Lal, R., Feller, C., Barthes, B., and Stewart, B.A. 2005. Soil erosion and carbon dynamics. CRC Press. 378p.
44.Sepe, L., Salis, M., Francaviglia, R., Fedrizzi, M., Carroni, A.M., Sabia, E., Bruno, A., Rufrano, D., Ruda, P., Dell’Abate, M.T., Alianello, A., Veloccia, M., Masetti, O., Renzi, G., Fanigliulo, R., Pagano, M., Sperandio, G., Guerrieri, M., Puri, D., and Claps, S. 2015. Environmental effectiveness of the cross compliance Standard 4.6 ‘Minimum livestock stocking rates and/or appropriate regimens’. Ital. J. Agron. 10: 1. 1-9.
45.Shi, X., Wang, H., Yu, D., Weindorf, D.C., Cheng, X., Pan, X., Sun, W., and Chen, J. 2009. Potential for soil carbon sequestration of eroded areas in subtropical China. Soil and Tillage Research. 105: 322-327.
46.Shifang, P., Hua, F., and Changgui, W. 2008. Changes in properties and vegetation following exclosure and grazing in degraded Alxa desert steppe of Inner Mongolia, China. Agriculture, Ecosystems and Environment. 124: 33-39.
47.Smith, P., Smith, J., Powlson, D., McGill, W., Arah, J., Chertov, O., Coleman, K., Franko, U., Frolking, S. and Jenkinson, D. 1997. A comparison of the performance of nine soil organic matter models using datasets from seven long-term experiments. Geoderma. 81: 153-225.
48.Spargo, J.T., Alley, M.M., Follett, R.F., and Wallace, J.V. 2008. Soil carbon sequestration with continuous no-till management of grain cropping systems in the Virginia coastal plain. Soil and Tillage Research. 100: 133-140.
49.Torabi, M. 1995. Application of the GLEAMS model for reduction of runoff, sediment and potential evapotranspiration from agricultural watersheds. M.Sc. thesis. College of Agriculture, University of Shiraz. (In Persian)
50.Tornquist, C.G., Mielniczuk, J., and Cerri, C.E.P. 2009. Modeling soil organic carbon dynamics in Oxisols of Ibirubá (Brazil) with the Century Model. Soil and Tillage Research. 105: 1. 33-43.
51.Vanaee, F., Karami, P., Joneydi, J.H., and Nabialahi, K. 2017. Simulation of soil organic carbon dynamic in meadow ecosystems under different management practices using CENTURY model. Rangeland. 10: 4. 439-449. (In Persian)
52.Vivanco, L., and Austin, A.T. 2006. Intrinsic effects of species on leaf litter and root decomposition: a comparison of temperate grasses from North and South America. Oecologia.150: 97-107.
53.Walkley, A., and Black, I.A. 1934. An examination of the Degtareff method for detwrmining soil organic matter and a proposed modification of the choromic acid titration method. Soil Science.37: 29-38.
54.Wang, Y., Zhou, G., and Binguri, J. 2008. Modeling SOC and NPP responses of meadow steppe to different grazing intensities in Northeast China. Ecological Modelling, 217: 72-78.
55.Wilson, C., Papanicolaou, A., and Abaci, O. 2009. SOM dynamics and erosion in an agricultural test field of the Clear Creek, IA watershed. Hydrology and Earth System Sciences Discussions. 6: 1581-1619.
56.Yadav, V. 2008. Soil carbon dynamics in the BIG CREEK basin, southern ILLINOIS USA. Doctoral Thesis, Geography, University of IWOA.
57.Yadav, V., and Malanson, G.P. 2009. Modeling impacts of erosion and deposition on soil organic carbon in the Big Creek Basin of southern Illinois. Geomorphology. 106: 304-314.
58.Yong-Zhong, S., Yu-Lin, L., Jian-Yuan, C., and Wen-Zhi, Z. 2005. Influences of continuous grazing and livestock exclusion on soil properties in a degraded sandy grassland, Inner Mongolia, northern China. Catena.59: 267-278.
59.Zhang, X. 2018.  Simulating eroded soil organic carbon with the SWAT-C model. Environmental Modelling and Software. 102: 39-48.