Impact of land use on soil organic carbon stocks in the humid tropics of NE Tanzania
Impact of land use on soil organic carbon stocks in the humid tropics of NE Tanzania
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DOI：
10.1002/jpln.201800595
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发表时间：
2019-08
影响因子：
2.5
通讯作者：
M. Kirsten;D. Kimaro;K. Feger;K. Kalbitz
中科院分区：
文献类型：
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作者：
M. Kirsten;D. Kimaro;K. Feger;K. Kalbitz
热带森林向农业用地的转化被认为是土壤有机碳储量下降的主要原因。然而，由于缺乏可靠的数据，不同土地利用方式对土壤有机碳储量发展的程度和影响是高度不确定的，特别是在热带非洲。有机碳与土壤矿化相的相互作用可以改变有机碳矿化的敏感性。成土性铁、铝氧化物和粘土可能会影响潮湿热带地区高度风化土壤的有机碳稳定。本研究的目的是确定不同土地利用方式对土壤有机碳储量的影响。为此，在对比土地利用的乌桑巴拉山脉东部（坦桑尼亚东北部阿曼尼自然保护区），对10个土壤学上相似的深风化酸性土壤（Acrisols, Alisols）进行了100厘米深度的采样。计算出的4个森林、2个茶园、3个农田和1个家庭菜园的平均碳储量分别为17.5 kg cm⁻²、16.8 kg cm⁻²、16.9 kg cm⁻²和20.0 kg cm⁻²。在0-10 cm深度的土地利用中，森林和农田土壤有机碳的平均储量有显著差异（1.3 kg C m⁻²）。未观察到土地利用对土壤有机碳储量的进一步显著影响。所有的土壤都有明显的粘土为主的质地。它们的特点是高含量的成土氧化物，表层土壤为29 ~ 47 g kg⁻¹，下层土壤为36 ~ 65 g kg⁻¹。土壤有机碳与粘土含量无显著正相关。仅在农田土壤中，草酸盐可提取的铁、铝和有机碳含量之间存在统计学上显著的正相关。与文献中发表的数据相比，我们研究中确定的SOC储量总体上与既定土地利用无关。在这些高度风化的热带土壤中，有效的有机碳稳定机制正在抵消农业用地下的高扰动状态。
The conversion of tropical forests to agricultural land use is considered as a major cause for a decline in soil organic carbon (SOC) stocks. However, the extent and impact of different land uses on SOC stock development is highly uncertain, especially for tropical Africa due to a lack of reliable data. Interactions of SOC with the soil mineral phase can modify the susceptibility of SOC to become mineralized. Pedogenic Fe‐, Al‐oxides and clay potentially affect SOC stabilization in highly weathered soils typically found in the humid tropics. The aim of our study was to determine the impact of different land uses on SOC stock on such soils. For that purpose, 10 pedologically similar, deeply weathered acidic soils (Acrisols, Alisols) in the Eastern Usambara Mountains (Amani Nature Reserve, NE Tanzania) under contrasting land use were sampled to a depth of 100 cm. The calculated mean SOC stocks were 17.5 kg C m⁻², 16.8 kg C m⁻², 16.9 kg C m⁻², and 20.0 kg C m⁻² for the four forests, two tea plantations, three croplands, and one homegarden, respectively. A significant difference in mean SOC stock of 1.3 kg C m⁻² was detected between forest and cropland land use for the 0–10 cm depth increment. No further significant impacts of land use on SOC stocks were observed. All soils have a clearly clay‐dominated texture. They are characterized by high content of pedogenic oxides with 29 to 47 g kg⁻¹ measured for the topsoils and 36 to 65 g kg⁻¹ for the subsoils. No positive significant relationship was found between SOC and clay content. Statistically significant positive relationships existed between oxalate‐extractable Fe, Al, and SOC content for cropland soils only. Compared to data published in literature the SOC stocks determined in our study were generally high independent of the established land use. It appears that efficient SOC stabilization mechanisms are counteracting the higher disturbance regime under agricultural land use in these highly weathered tropical soils.