土地利用/覆被变化和坡度梯度对埃塞俄比亚西北部 Anjeni 流域土壤有机碳储量的影响。

Impact of land use/cover change and slope gradient on soil organic carbon stock in Anjeni watershed, Northwest Ethiopia.

机构信息

Africa Centre of Excellence for Climate-Smart Agriculture and Biodiversity Conservation, Haramaya University, Haramaya, Ethiopia.

College of Agriculture and Natural Resource Sciences, Debre Birhan University, P.O. Box 445, Debre Birhan, Ethiopia.

出版信息

Environ Monit Assess. 2023 Jul 19;195(8):971. doi: 10.1007/s10661-023-11537-7.

DOI:10.1007/s10661-023-11537-7

PMID:37466748

Abstract

Today's agri-food systems face the triple challenge of addressing food security, adapting to climate change, and reducing the climate footprint by reducing the emission of greenhouse gases (GHG). In agri-food systems, changes in land use and land cover (LULC) could affect soil physicochemical properties, particularly soil organic carbon (SOC) stock. However, the impact varies depending on the physical, social, and economic conditions of a given region or watershed. Given this, a study was conducted to quantify the impact of LULC and slope gradient on SOC stock and C sequestration rate in the Anjeni watershed, which is a highly populated and intensively cultivated area in Northwest Ethiopia. Seventy-two soil samples were collected from 0-15 and 15-30 cm soil depths representing four land use types and three slope gradients. Soil samples were selected systematically to match the historical records (30 years) for SOC stock comparison. Four land use types were quantified using Landsat imagery analysis. As expected, plantation forest had a significantly (p < 0.05) higher SOC (1.94 Mg ha) than cultivated land (1.38 Mg ha), and gentle slopes (1-15%) had the highest SOC (1.77 Mg ha) than steeper slopes (> 30%). However, higher SOC stock (72.03 Mg ha) and SOC sequestration rate (3.00 Mg ha year) were recorded when cultivated land was converted to grassland, while lower SOC stock (8.87 Mg ha) and sequestration rate (0.77 Mg ha year) were recorded when land use changed from cultivation to a plantation forest. The results indicated that LULC changes and slope gradient had a major impact on SOC stock and C sequestration rate over 30 years in a highly populated watershed. It is concluded that in intensively used watersheds, a carefully planned land use that involves the conversion of cultivated land to grassland could lead to an increase in soil C sequestration and contributes to reducing the carbon footprint of agri-food systems.

摘要

今天的农业食品系统面临着三重挑战，即解决粮食安全问题、适应气候变化以及通过减少温室气体（GHG）排放来减少气候足迹。在农业食品系统中，土地利用和土地覆被（LULC）的变化可能会影响土壤物理化学性质，特别是土壤有机碳（SOC）储量。然而，这种影响因特定地区或流域的物理、社会和经济条件而异。鉴于此，进行了一项研究，以量化 LULC 和坡度梯度对埃塞俄比亚西北部人口密集且集约化耕作的 Anjeni 流域 SOC 储量和 C 固存率的影响。从 0-15 和 15-30 cm 土壤深度采集了 72 个土壤样本，代表四种土地利用类型和三个坡度梯度。土壤样本是系统地选择的，以匹配 SOC 储量的历史记录（30 年）进行比较。使用 Landsat 图像分析量化了四种土地利用类型。不出所料，种植园森林的 SOC（1.94 Mg ha）明显高于耕地（1.38 Mg ha），而坡度较缓（1-15%）的 SOC（1.77 Mg ha）高于坡度较陡（> 30%）。然而，当耕地转变为草地时，SOC 储量（72.03 Mg ha）和 SOC 固存率（3.00 Mg ha 年）最高，而当土地利用从耕地变为种植园森林时，SOC 储量（8.87 Mg ha）和固存率（0.77 Mg ha 年）最低。结果表明，在人口密集的流域中，LULC 变化和坡度梯度在 30 多年内对 SOC 储量和 C 固存率产生了重大影响。结论是，在集约化利用的流域中，精心规划的土地利用，包括将耕地转化为草地，可以增加土壤 C 固存，并有助于减少农业食品系统的碳足迹。