Land use-land cover gradient demonstrates the importance of perennial grasslands with intact soils for building soil carbon in the fertile Mollisols of the North Central US
Land use-land cover gradient demonstrates the importance of perennial grasslands with intact soils for building soil carbon in the fertile Mollisols of the North Central US
复制标题
DOI：
10.1016/j.geoderma.2022.115854
复制
发表时间：
2022-07
期刊：
影响因子：
6.1
通讯作者：
G. Sanford;R. Jackson;Y. Rui;C. Kucharik
中科院分区：
文献类型：
--
作者：
G. Sanford;R. Jackson;Y. Rui;C. Kucharik
土地利用变化和农业管理对土壤有机碳循环的影响尚不清楚，这限制了我们在局部和区域尺度上对土壤碳变化进行管理和准确建模的能力。为了解决这一问题，我们将长期土壤培养与酸水解和干燃烧相结合，将总有机碳（Ct）解析为3个可操作定义的有机碳池（活性、缓慢和顽固），这些有机碳池来自9个长期场地，在现有和以前的高草草原土壤中具有不同的土地利用方式。土地利用表现为残余草原、恢复草原、放牧草地、轮作和连续种植玉米等土壤扰动历史的梯度。干燃烧用于估计总碳（Ct，物理），而酸水解活性（Ca）和慢化（Cs）池用于估计顽固性碳池（Cr，化学）。然后使用长期孵育的co2流出数据的非线性建模来估计eca，以及ca和cs的分解率（kaandkr，生物）。然后用数学方法将慢池sc的大小定义为ct -(Ca+Cr)。剩余草原的碳排放系数最高，而冷季牧场和35年的恢复草原的碳排放系数高于其他农业系统。包括牧场在内的所有农业系统中，ctascr的比例最高（~ 50%），其在这些土壤中的平均停留时间(MRT)≥500年（Paul等人，2001a），表明这一比例持续存在，而更不稳定的部分则在几个月（Ca）到几十年（Cs）的过程中损失，这是耕作集约化农业的结果。二至四十年的捷运时间表明，池可能对某些地点20至40年的土地使用实践更敏感。与农业生态系统相比，残余和35年龄草原的碳池最大，表明碳积累和稳定显著。有趣的是，残余草原也保持了最高的capool，这表明新鲜碳输入的数量与长期碳稳定和积累的潜力之间存在很强的联系。活跃（≈不稳定）碳池中碳的积累是迈向长期稳定的第一步，这凸显了早期碳收益的脆弱性质，这些收益可能会因气候变化或管理不善而迅速损失。
The impact of land use change and agricultural management on the cycling of soil organic carbon (SOC) is not well understood, limiting our ability to manage for, and accurately model, soil carbon changes at both local and regional scales. To address this issue, we combined long-term soil incubations with acid-hydrolysis and dry combustion to parse total SOC (Ct) into three operationally defined SOC pools (active, slow, and recalcitrant) from 9 long-term sites with varying land uses on current and former tallgrass prairie soil. Land uses represented a gradient of soil disturbance histories including remnant prairie, restored prairie, grazed pasture, annual crop rotations, and continuous maize. Dry combustion was used to estimate total carbon (Ct, physical), while acid hydrolysis of both the active (Ca) and slow (Cs) pools was used to estimate a recalcitrant carbon pool (Cr, chemical). Non-linear modeling of CO2efflux data from the long-term incubations was then used to estimateCa, and the decomposition rates of bothCaandCs(kaandkr, biological). The size of the slow poolsCswas then defined mathematically asCt-(Ca+Cr). Remnant prairie had the highestCt, while cool-season pasture and a 35-y-old restored prairie had higherCtthan the other agricultural systems. All agricultural systems, including pasture, had the highest fraction ofCtasCr(∼50%), whose mean residence time (MRT) in these soils is ≥500 years (Paul et al., 2001a) demonstrating that this fraction persists, while the more labile fractions were lost over the course of a few months (Ca) to a few decades (Cs) as a result of tillage-intensive agriculture. The two- to four-decade MRT time ofCsindicated a pool likely to be more responsive to the 20 to 40 years of land-use practices used at some of the sites. TheCspool was largest in the remnant- and 35-y-old prairies indicating significant C accrual and stabilization compared to the agricultural ecosystems. Interestingly, the remnant prairie maintained the highestCapool as well, demonstrating the strong connection between the quantity of fresh C inputs and the potential for long-term C stabilization and accrual. The accumulation of C in active (≈labile) pools as a first step toward long-term stabilization highlights the tenuous nature of early carbon gains, which can be quickly lost in response to climate change or poor management.