بررسی و شبیه‌سازی اثر تغییر اقلیم، چرای دام و مصرف کود دامی بر ذخیره کربن آلی خاک‌های جنگلی ارتفاعات مختلف با مدل سنچری

نوع مقاله : مقاله پژوهشی

نویسندگان

• مهران میثاقی ¹
• احمد گلچین ²
• محمد صادق عسکری ³

¹ گروه مهندسی خاک دانشکده کشاورزی دانشگاه زنجان زنجان ایران

² گروه مهندسی خاک. دانشکده کشاورزی. دانشگاه زنجان. زنجان. ایران

³ گروه علوم خاک دانشکده کشاورزی، دانشگاه زنجان

چکیده

کلیدواژه‌ها

• ذخیره کربن آلی خاک
• تغییر اقلیم
• چرا
• کود دامی
• مدل سنچری

موضوعات

• شیمی خاک

عنوان مقاله [English]

Investigating and simulating the effect of climate change, grazing and manure application on organic carbon storage of forest soils at different altitudes with the Century model

نویسندگان [English]

• Mehran Misaghi ¹
• Ahmad Golchin ²
• Mohammad Sadegh Askari ³

کلیدواژه‌ها [English]

• Soil organic carbon storage
• Climate change
• Grazing
• Manure application
• Century model

EXTENDED ABSTRACT

Introduction

Forests are vital global carbon sinks, orchestrating climate regulation, biodiversity preservation, and human well-being. They excel at storing atmospheric carbon as soil organic matter, but this critical function faces threats from climate change and anthropogenic activities like grazing and manure application. This research delves into the intricate interplay of these factors and their impact on organic carbon content in the temperate forests of Talesh, Iran, paving the way for sustainable forest management strategies.
Materials and MethodsAcross four distinct altitude classes (500-1000, 1000-1500, 1500-2000, and 2000-2500 meters above sea level), capturing a range of climatic and environmental gradients, soil samples were analyzed for organic carbon content, soil texture, pH, and salinity.

Annual mean precipitation and temperature varied significantly with altitude, with precipitation decreasing (1,247.26 to 2,052.02 millimeters) and temperature falling (26.93 to 15.83 degrees Celsius) as elevation increased. Evapotranspiration followed similar patterns, decreasing from 1,238.38 to 740.76 millimeters across the gradient. To explore the potential impacts of climate change, grazing, and manure application under various scenarios, the renowned Century C Model, a tool for simulating soil organic carbon dynamics, was employed.

Results

While soil texture, pH, and salinity showed no significant variation across altitudes, a remarkable positive correlation emerged between altitude and organic carbon content. Higher altitudes, characterized by increased rainfall and lower temperatures, fostered an environment conducive to greater storage, with the highest levels (97.46 tons per hectare) observed at 2,000-2,500 meters and the lowest (44.23 tons per hectare) found at 500-1,000 meters. The Century C Model demonstrated remarkable accuracy in its predictions, boasting a correlation coefficient and coefficient of determination exceeding 0.98. The model paints a concerning picture under the status quo scenario, predicting a gradual decrease in soil organic carbon storage over time. This reduction, ranging from 2.48 to 9.57 tons per hectare across the altitude classes, can be attributed to factors like soil erosion, nutrient leaching, and reduced forest fertility. The cumulative release of carbon dioxide due to soil organic matter decomposition further contributes to rising CO2 levels, with higher emission rates observed at higher elevations due to their greater carbon input and storage.
Climate change simulations reveal a particularly alarming scenario. A projected decrease in rainfall (2.15 millimeters per 10 years) coupled with a temperature increase (0.4 degrees Celsius) is predicted to cause a substantial decrease (28.36-36.35%) in organic carbon storage across all altitude classes, with higher altitudes exhibiting greater vulnerability.

Grazing's negative impact on organic carbon content was undeniable, increasing linearly with intensity and further amplified at higher altitudes. In contrast, manure application at a rate of 40 tons per hectare every four years demonstrably increased organic carbon levels, again with a more pronounced effect at higher elevations. However, combining the simulated climate change scenario with manure application revealed a nuanced picture. While manure use effectively mitigated some of the negative impacts, it could not entirely counteract them, with organic carbon reductions of 1.49 to 5.42% still observed under these combined conditions. The study identified several factors influencing soil carbon dioxide (CO₂) emissions: climate change, grazing, and livestock manure application. Climate change and grazing scenarios both exhibited reduced CO₂ emissions compared to the current state. This likely stems from decreased plant residue production induced by drought (climate change) and excessive grazing pressure.

Combining climate change with livestock manure application also led to lower CO₂ emissions compared to the baseline, but the effect was smaller than observed in both climate change and grazing scenarios. This suggests that, while manure application supplements soil carbon through added organic matter, its potential reduction effect on CO₂ emissions appears limited in these circumstances.

In contrast, the livestock manure application scenario alone generated increased CO₂ emissions. This is directly attributable to the enhanced carbon input into the soil via manure application, ultimately fueling microbial respiration and CO₂ release.

Conclusion

This research emphasizes the critical role of elevation in controlling organic carbon storage within forest soils. Additionally, it reaffirms the remarkable accuracy of the Century C Model in simulating these dynamics. The findings paint a sobering picture of the threats posed by climate change and grazing to carbon storage. However, they also highlight the potential benefits of responsible manure application, albeit with limitations. These insights underscore the importance of preserving diverse forest elevations and implementing sustainable management practices. Minimizing detrimental activities and promoting organic carbon replenishment through responsible manure application and other strategies emerge as crucial steps in combatting climate change and ensuring the long-term health of our vital forest ecosystems.

Authors Contributions

Mehran Misaghi: Methodology, Formal analysis, Investigation, Resources, Writing (Original Draft and Editing); Ahmad Golchin: Methodology, Conceptualization, Supervision, Resources; Mohammadsadegh Askari: Editing, Investigation, Resources.

Data Availability

Data available on request from the authors.

Acknowledgements

The authors would like to thank the University of Zanjan, Zanjan, Iran for the financial and technical support that made this study possible.

Conflict of Interest

The authors declare that they have no conflict of interest.