اثر قرق بلندمدت بر میزان ذخیره کربن خاک در مراتع مشجر نیمه گرمسیری استان خوزستان
محورهای موضوعی : مدیریت بهینه منابع آب و خاکمهدی عباسی 1 , بهناز عطائيان 2 * , مينا ربيعي 3 , علی رستمی خانی زاده 4
1 - دانش آموخته کارشناسي ارشد، گروه مهندسي طبيعت، دانشکده منابع طبيعي و محيط زيست، دانشگاه ملاير، ملاير، ايران.
2 - استاديار گروه مهندسي طبيعت، دانشکده منابع طبيعي و محيط زيست، دانشگاه ملاير، ملاير، ايران.
3 - دانشيار، گروه منابع طبيعي و محيط زيست، دانشگاه پيام نور، تهران، ايران.
4 - کارشناسي ارشد، اداره کل محيط زيست استان لرستان، خرم آباد، ايران.
کلید واژه: پارک ملي کرخه, ترسيب کربن, مديريت مرتع,
چکیده مقاله :
زمينه و هدف: مراتع محل ذخيره بيش از يک سوم کربن زيستکره خاکي هستند که قادرند دي اکسيد کربن اتمسفري را از طريق پوشش گياهي جذب کرده و در بافتهاي گياهي و سپس خاک ذخيره کنند.تغييرات کمّي و کيفي ماده آلي لاشبرگ، پوشش هوايي، زيست‌توده زيرزميني و ترکيب خاک باشد. بهطورکلي، عدم يکنواختي آثار چرا بر پتانسيل ترسيب کربن در اکوسيستمهاي مرتعي در مناطق مختلف لزوم مطالعه و بررسي مديريتهاي چرايي در مناطق مختلف را گوشزد مينمايد. باتوجه به اينکه بخش اعظم استان کردستان در سيطره منطقه نيمهاستپي ميباشد و چراي دام بهعنوان اصليترين نوع کاربري در اين مراتع بهشمار ميآيد، بنابراين در اين پژوهش اثر قرق بلندمدت مراتع مشجر نيمهگرمسيري بر ذخيره کربن آلي خاک پارک ملي کرخه، استان خوزستان مورد بررسي قرار گرفت.
روش پژوهش: جهت انتخاب مکان نمونهبرداري محدوديتي از لحاظ شرايط توپوگرافي وجود ندارد به همين در قالب يک طرح کاملا تصادفي، تعداد 4 مقطع- برش عرضي 100 متري انتخاب شده و در طول هر ترانسکت تعداد 14 نمونه خاک در دو عمق 0 تا 10 و 10 تا 30 سانتيمتر با توجه به بررسيهاي انجام شده و تعيين مرز تفکيک افق سطحي و زيرين برداشت ميشود که جهت مقايسه ميزان کربن تثبيت شده به همين تعداد نمونهگيري از منطقه چراي آزاد نيز صورت گرفت. سپس خصوصيات فيزيکي و شيميايي خاک از جمله کربن، نيتروژن، بافت خاک، وزن مخصوص ظاهري، هدايت الکتريکي ((EC و اسيديته خاک (pH) اندازهگيري شد. نمونه خاکهاي هوا خشک شده و بعد از خرد کردن کلوخهها، جدا کردن ريشهها، سنگ و ديگر ناخالصيها، آسياب شده و از الک 2 ميليمتر (مش20) عبور داده شدند. براي اندازهگيري كربن آلي خاك از روش والكي- بلاك و به منظور محاسبة وزن مخصوص ظاهري از روش كلوخه استفاده شد پس از جمعآوري داده‌ها با استفاده از نرمافزار SPSS ورژن 18 و از طريق مقايسه ميانگين داده‌ها با آزمون t-test مستقل استفاده شد. سطح معنيداري معادل 05/0 و 01/0 در نظر گرفته شد. لازم بذکر است قبل از انجام آناليزها، پيش فرضهاي مورد نياز که نرماليتي و همگني واريانسها بودند، مورد بررسي قرار گرفتند.
يافتهها: نتايج حاصل از تجزيه خصوصيات فيزيکي و شيميايي خاک در دو عمق0 تا 10 (سطحي) و 10 تا 30 سانتيمتر (زيرسطحي) در منطقه قرق و چرا، نشان داد که قرق و چرا بر ذخيره کربن خاک سطحي (عمق10-0 سانتيمتر)، مقدار نيتروژن خاک (عمق10-0 سانتيمتر) و ميزان وزن مخصوص ظاهري تأثيرگذار و با يک اثر افزاينده همراه هستند. به نظر ميرسد خاک اين مناطق به علت داشتن زيتوده هوايي و زير زميني گياه داراي مواد آلي و نيتروژن زيادي هستند. با وجود اين موارد اثر معنيداري بر ميزان اسيديته خاک در دو منطقه قرق و چرا مشاهده نشد که ميتواند بهعلت مواد مادري يکسان خاک دو منطقه باشد. همچنين چرا برخلاف قرق بر ميزان هدايت الکتريکي (EC) در عمق10-0 سانتيمتر اثر معنيداري و کاهشي داشت. همچنين در نسبت C/N موجود در خاک منطقه قرقشده برخلاف منطقه چرا در عمق10-0 سانتيمتر اثر معنيداري مشاهده شد. يافتههاي منطقهاي که قرق و چرا در آن صورت گرفته بود، حاکي از اين بود که در اين منطقه قرق باعث اثر افزايشي و معنيداري در مقدار ذخيره کربن خاک سطحي (عمق10-0 سانتيمتر)، مقدار نيتروژن خاک (عمق10-0 سانتيمتر)، ميزان اسيديته خاک (عمق10-0 سانتيمتر) و ميزان هدايت الکتريکي (EC) (عمق10-0 سانتيمتر) شده است. همچنين چراي انجام شده در اين منطقه حفاظتي بر ميزان وزن مخصوص ظاهري (عمق10-0 سانتيمتر) تأثير افزايشي و معنيداري داشته است. ليکن با اين وجود در قرق و چرا در اين منطقه بر نسبت C/N موجود در خاک اثر معنيداري نداشته است.
نتيجه‌گيري: بهطور کلي نتايج مطالعه حاضر گوياي اين مطلب است که خاک اراضي قرق نسبت به خاک اراضي چرا شده از لحاظ خصوصيات فيزيکي و شيميايي خاک وضعيت مطلوبتر و بهتري را جهت افزايش ترسيب کربن دارد و چون بهرهبرداريهاي بيرويه در اکوسيستمهاي چرا شده باعث کاهش ميزان توليد و ترسيب کربن مراتع گرديده است. پس اجراي برنامههاي اصلاحي و مديريتي متداول مانند قرق جهت افزايش ترسيب کربن و توليد علوفه در اکوسيستمهاي مرتعي متفاوت امري ضروري بنظر ميرسد.
Background and Aim: Rangelands serve as a storage for more than one-third of the Earth’s carbon stocks, absorbing atmospheric carbon dioxide through vegetation and store it in plant tissues and subsequently in the soil. Changes in the quantity and quality of organic matter can be influenced by litter, canopy cover, underground biomass, and soil composition. Generally, the inconsistency of grazing effects on the carbon sequestration potential in rangeland ecosystems across different regions highlights the need for study and examination of grazing management practices in various areas. Considering that most of Kurdistan province lies within the semi-steppe region and livestock grazing is regarded as the primary land use in these rangelands, this research investigates the effect of long-term enclosed of semi-steppe wooded grasslands on soil organic carbon storage in Karkheh National Park, Khuzestan Province.
Methods: To select the sampling locations, there were no restrictions in terms of topographic conditions. Therefore, four 100-meter transects were randomly In completely random design and 14 soil samples were collected along each transect at two depths of 0 to 10 cm and 10 to 30 cm, based on previous studies and the determination of the boundary distinguishing the surface and subsurface soil horizons. To compare the amount of carbon storage, an equal number of samples were also collected from an grazed area. Subsequently, the physical and chemical properties of the soil, including the carbon, nitrogen, texture, bulk density, electrical conductivity (EC), and acidity (pH) were measured. The soil samples were air-dried, and after crushing the aggregates, separating roots, stones, and other impurities, they were ground and passed through a 2 mm sieve (mesh 20). The Walkley-Black method was used to measure soil organic carbon, and the aggregate method was used to calculate bulk density. After collecting the data, SPSS v.18 was used to do independent t-test comparing the average values. Significance levels of 0.05 and 0.01 were considered. Prior to statistical analysis, the necessary assumptions regarding normality and homogeneity of variances were checked.
Results: The results showed the analysis of the physical and chemical properties of the soil at two depths of 0 to 10 cm (surface) and 10 to 30 cm (subsurface) in enclosed and grazing areas indicated that enclosed and grazed treatments significantly affected soil carbon storage at the surface depth (0-10 cm), the amount of soil nitrogen (0-10 cm), and the bulk density showing an increasing effect associated with depth. It appears that the soil in both areas have high organic matter and nitrogen content due to the aboveground and underground plant biomass. However, no significant change was observed on soil acidity between both the enclosed and grazed areas, which could be due to the same soil parent materials in both study sites. Additionally, grazing, in contrast to enclosed, had a significant and decreasing effect on electrical conductivity (EC) at the depth of 0-10 cm. A significant effect was also observed in the C/N ratio in the soil of the enclosed area compared to the grazing area at the depth of 0-10 cm. The findings indicated that in the study area, protection led to a significant increase in the amount of soil carbon storage at the surface depth (0-10 cm), the amount of soil nitrogen (0-10 cm), soil acidity (0-10 cm), and electrical conductivity (EC) (0-10 cm). Furthermore, the grazing had a significant increasing effect on the bulk density (0-10 cm). Nevertheless, neither encosion nor grazing had a significant effect on the C/N ratio in the soil of the study area.
Conclusion: Overall, the results of the present study indicate that the soil of enclosed area has more suitable conditions for increasing soil carbon sequestration compared to the soil of grazed areas in terms of physical and chemical properties. Excessive exploitation in grazing ecosystems has led to a reduction in carbon storage and sequestration in rangelands. Therefore, implementing common remediation and management programs, such as exclusion, seems essential for enhancing carbon sequestration and forage production in various rangeland ecosystems.
Abrigo, M., Lezama, F., Grela, I. & Piñeiro, G. (2024). Grazing exclusion effects on vegetation structure and soil organic matter in savannas of río de la plata grasslands. Journal of Vegetation Science, 35(5).
Attaeian, B., Karami, F., Akhzari, D. & Kiani, G. A. (2023). Comparative Study of Vegetation Parameters, Soil Elements, and Organic Carbon Storage in Mountain Rangelands under Exclosure and Grazing Management: A Case Study in Asadabad, Hamadan. Journal of Rangeland, 17(2), 247-262. [in Persian]
Atsbha, T., Desta, A. B. & Zewdu, T. (2019). Carbon sequestration potential of natural vegetation under grazing influence in Southern Tigray, Ethiopia: implication for climate change mitigation. Heliyon, 5(8).
Bremner, J.M. & Mulvaney, C.S. (1982). Nitrogen-total. In: page, AL, Miller, RH, Keeney, RR, (Eds), Methods of soil analysis, and Part 2. Second ed. American society of agronomy, Madison, WI, 624 p.
Blake, G.R. & Hartge, K.H.¬ (1995). Bulk density. In: Klute, A. (Ed.), Methods of Soil Analysis. Part I. Physical and Mineralogical Methods. Soil Sci. Soc. Am. Pub, 9(1), 363-376.
Burke, I.C., Laurenroth, W.K. & Milchunas, D.G. (1997). Biogeochemistry of Managed Grasslands in Central North America. In: Paul, E.A., K. Paustian, E.T. Elliott & C.V. Cole (Eds.), Soil Organic Matter in Temperate Agroecosystems: Long-term Experiments in North America. CRC Press, Boca Raton, FL, 85–102.
Cannell, G.R. (2003). Carbon sequestration and biomass energy offset theoretical, potential and achievable capacities globally in Europe and UK. Biomass and Bioenergy, 24, 97-116.
Chen, L. & Baoyin, T. (2024). Effects of plant productivity and species on soil carbon and nitrogen sequestration under seasonal grazing in a semi‐arid grassland of north china. Land Degradation and Development, 35(5), 1960-1970.
Fenetahun, Y., Yuan, Y., Xu, X., Fentahun, T., Nzabarinda, V., & Wang, Y. (2021). Impact of grazing intensity on soil properties in teltele rangeland, ethiopia. Frontiers in Environmental Science, 9, 664104.
Gee, G.W. & Bauder, J.W. (1986). Particle-size analysis, in A, Klute, ed. Methods of soil analysis, soil science society of America, Madison, Wiscon, pp.383–411.
Gebregergs, T., Tessema, Z., Solomon, N. & Birhane, E. (2019). Carbon sequestration and soil restoration potential of grazing lands under exclosure management in a semi‐arid environment of northern ethiopia. Ecology and Evolution, 9(11), 6468-6479.
Ghorbani, N., Raiesi, F. & Ghorbani, Sh. (2012). Influence of Livestock Grazing on the Distribution of Organic Carbon, Total Nitrogen and Carbon Mineralization within Primary Particle-Size Fractions in Shayda Rangelands with Cropping History. Iranian Journal of Soil and Water, 23(1), 209-222¬. [in Persian]
Hashimoto. M., Nose, T. & Muriguchi, Y. (2002). Wood products: ia carbon sequestration and impact on net carbon emissions of i cruntries. Environmental Science & Policy, 5, 183-193.
He, N.P., Zhang, Y.H., Yu, Q., Chen, Q.S., Pan, Q.M., Zhang, G.M. & Han, X.G. (2011). Grazing intensity impacts soil carbon and nitrogen storage of continental steppe. Ecosphere, 2(1), 1-10.
Hui, D., Deng, Q., Tian, H. & Luo, Y. (2017). Climate change and carbon sequestration in forest ecosystems. Handbook of climate change mitigation and adaptation, 594p.
Hu, Z., Li, S., Guo, Q., Niu, S., He, N., Li, L. & Yu, G. (2016). A synthesis of the effect of grazing exclusion on carbon dynamics in grasslands in china. Global Change Biology, 22(4), 1385-1393.
Jafari, M., Azarnivand, H. Sadeghipour, A., Kamali, N., Heydari, A. & Madah Arefi, H. (2015). The effects of different intensities of livestock grazing on carbon sequestration and soil nitrogen storage (case study: Chahar Shahriar plot). Pasture and watershed management. Journal of natural resources of Iran, 69(2), 353-366¬. [in Persian]
Jahantab, E., Mirzaee, M. & Gholami, P. (2019). The effect of Drill seeded exclosures on vegetation changes using multivariate analysis in Tang-e-Sorkh rangelands in Boyerahmad province, Iran. Rangeland, 13(2), 274-284¬. [in Persian]
Jalilund, H., Mortash, R. & Vahidpour, H. (¬2006). The effect of plant cover and some chemical properties of soil in Kajor pastures of Nowshahr. Pasture Journal, 66, 1-53¬. [in Persian]
Joneidi, H., Amani, S. & Kerami, P. (2015). The effect of livestock grazing intensity on sedimentation and carbon storage in Bijar protected pastures. Marta Research Journal, 10(1), 53-67¬. [in Persian]
Kamali, N., Eftekhari, A., Soori, M., Nateghi, S. & Bayat, M. (2020). Grazing impact on vegetation cover and some soil factors (Case study: Houz-e-Soltan Lake, Qom). Journal of Rangeland, 14(1), 85-94¬. [in Persian]
Khanizadeh, A.R., Erfanzadeh, R. & Siah Mansour, R. (2014). Investigating the effect of livestock grazing on the underground organs of Festuca ovina species in the semi-arid pastures of Lorestan. Second International Conference on Sustainable Development and Solutions and Challenges, pp. 24-26¬. [in Persian]
Khodadost, M., Saberi, M. & Tarnian, F. (2022). The carbon and nitrogen storage capacity of soil in two enclosure and grazed sites (Case study: Kote rangelands of Khash City). Rangeland, 16(3), 441-453¬. [in Persian]
Lal, R. (2004). Soil carbon sequestration impact on global climate change andfood security. Science, 304: 1623-1627.
Li, G., Zhang, Z., Shi, L., Zhou, Y., Yang, M., Cao, J. & Lei, G. (2018). Effects of different grazing intensities on soil c, n, and p in an alpine meadow on the Qinghai-tibetan plateau, china. International Journal of Environmental Research and Public.
Liang, M., Smith, N., Chen, J., Wu, Y., Guo, Z., Gornish, E., & Liang, C. (2021). Shifts in plant composition mediate grazing effects on carbon cycling in grasslands. Journal of Applied Ecology, 58(3), 518-527.
Moradi Shahghariyeh, M. and Tahmasbi, P., 2016. The effect of enclosure on carbon sequestration and soil physical and chemical properties in semi steppe rangelands of Chaharmahal and Bakhtiari Province. Natural ecosystem of Iran, 6(4): 97-109¬. [in Persian]
Ntalo, M., Ravhuhali, K., Moyo, B., Mmbi, N. & Mokoboki, H. (2022). Physical and chemical properties of the soils in selected communal properties associations of south africa. Peerj, 10, e13960.
Riahi Samani, M. & Raisi, F. (2013). Carbon dynamics in natural pastures under grazing and flooding in three grassland ecosystems of the Central Zagros Mountains, Water and Soil Journal (Agricultural Sciences and Industries), 28(4), 753-742¬. [in Persian]
Schuman, G.E., Janzen, H.H. & Herrick, J.E. (2002). Soil carbon dynamics and potential carbon sequestration by rangelands. Environmental Pollution, 116, 391- 396.
Shariff, A.R, Biondini, M.E. & Grtgiel, C.E. (1994). Grazing intensity effects on litter decomposition and soil nitrogen mineralization. Journal of Range Management, 47, 444- 449.
Sun, J., Wang, X., Cheng, G., Wu, J., Hong, J., & Niu, S. (2014). Effects of grazing regimes on plant traits and soil nutrients in an alpine steppe, northern tibetan plateau. Plos One, 9(9), e108821.
Sun, D.S., Wesche, K., Chen, D.D., Zhang, S.H., Wu, G.L., Du, G.Z. & Comerford, N.B. (2011). Grazing depresses soil carbon storage through changing plant biomass and composition in a Tibetan alpine meadow. Plant soil environment, 57 (6), 271–278.
Thomson, A. (2008). Integrated estimates of global terrestrial carbon sequestration. Global Environmental Change, 18, 192–203.
Wang, L., Gan, Y., Wiesmeier, M., Zhao, G., Zhang, R., Han, G. & Hou, F. (2018). Grazing exclusion—an effective approach for naturally restoring degraded grasslands in northern china. Land Degradation and Development, 29(12), 4439-4456.
Zhu, G., Yuan, C., Gong, H., Peng, Y., Huang, C., Wu, C. & Duan, H. (2021). Effects of short-term grazing prohibition on soil physical and chemical properties of meadows in southwest china. Peerj, 9, e11598.