Deforestation and land use strongly effect soil organic carbon and nitrogen stock in Northwest Ethiopia

Assefa, Dessie; Rewald, Boris; Sandén, Hans; Rosinger, Christoph; Abiyu, Abrham; Yitaferu, Birru; Godbold, Douglas L.

doi:10.1016/j.catena.2017.02.003

Cited by 107 publications

(98 citation statements)

References 66 publications

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“…Each study area covers two different land use forms located next to each other: (i) natural forests and (ii) agricultural land. The agricultural land was established on former natural forest about 40 to 50 years ago [32]. This paired-plot approach enabled us to directly address the impact of land use changes, as climatic and site conditions can be assumed having been similar.…”

Section: Study Areasmentioning

confidence: 99%

“…All soil samples were taken at the same time as the forest soil samples. For further details, we refer to [32].…”

Section: Agricultural Areamentioning

confidence: 99%

“…For all four forest areas, cutting of selected high valuable trees and the removal of suppressed trees for fuelwood was reported (from interviews, documents, [32]). Based on these indications of intensive and uncontrolled extractions, we assumed an annual harvest of 5% of the biomass, as harvest must be assumed to be clearly more than the 3% mortality from the eco-physiological parameter set [66].…”

Section: Current Forestsmentioning

confidence: 99%

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The Carbon Dynamics of Dry Tropical Afromontane Forest Ecosystems in the Amhara Region of Ethiopia

Belay

Pötzelsberger

Sisay

et al. 2018

Forests

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Forest degradation due to land use change is a severe problem in Ethiopian Afromontane Forests. We investigated such degradation effects by comparing degraded agricultural land (previously covered with forest) with neighboring natural forests, 40 to 50 years after conversion. We selected four different study areas to cover the eco-climatic conditions of the Amhara region in Northwestern Ethiopia. For a paired-stand comparison we collected soil data on both land use types. We calculated forest biomass to evaluate the biogeochemical-mechanistic ecosystem model Biome-BGC, which is used as a diagnostic tool to assess the site and management impacts on productivity as well as ecosystem carbon and nitrogen accumulation. We applied Biome-BGC to assess rehabilitation options on such degraded land. Afromontane forests in the highlands of Ethiopia showed high soil C stocks, resulting from long lasting biomass accumulation. Removing the tree cover and converting forest areas to crop-or grassland, has led to a loss of 40-85% of the soil C stocks and thus a loss in soil fertility within only 40 to 50 years. Rehabilitation efforts by replanting trees will improve soil fertility, but may require over a thousand years to achieve a similar level in biomass and soil fertility versus the situation prior to the land use change.

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Section: Study Areasmentioning

confidence: 99%

“…All soil samples were taken at the same time as the forest soil samples. For further details, we refer to [32].…”

Section: Agricultural Areamentioning

confidence: 99%

Section: Current Forestsmentioning

confidence: 99%

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The Carbon Dynamics of Dry Tropical Afromontane Forest Ecosystems in the Amhara Region of Ethiopia

Belay

Pötzelsberger

Sisay

et al. 2018

Forests

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“…Typically, it is impossible to find detailed field inventory data at a larger scale. For our study, only few empirical mineral soil data were available from local inventories, including data collected in one of our previous studies [5,9,[55][56][57][58][59][60][61]. From these published results, we derived mean soil carbon and nitrogen by land use type and a correction factor for soil carbon and nitrogen from a preparatory spin-up simulation to obtain spatially explicit soil carbon and nitrogen stocks across the study area as a starting condition for the reforestation simulations.…”

Section: Initial Soil Conditionsmentioning

confidence: 99%

“…Additionally, we see heavy disturbances in the remaining natural forests, such as cattle grazing or logging that result in severe soil degradation [8][9][10]. A study in the north-western highlands of Ethiopia revealed a decrease in natural forest cover from 27% in 1957 to 2% in 1982 and to 0.3% in 1995 [11].…”

Section: Introductionmentioning

confidence: 98%

The Carbon Sequestration Potential of Degraded Agricultural Land in the Amhara Region of Ethiopia

Belay

Pötzelsberger

Hasenauer

2018

Forests

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Forests are a key player within the global carbon cycle and reforestation is an important climate change mitigation mechanism. In this study, we identify potentially suitable areas for reforestation to assess the carbon sequestration potential in the highly deforested and degraded Amhara region of Ethiopia. We apply biogeochemical mechanistic ecosystem modelling to predict the amount of carbon that can be potentially sequestered within different time horizons. Since human intervention plays a key role within the Amhara region, three different forest management scenarios and five different rotation periods following reforestation are tested: (i) unthinned; (ii) removal of 5% of the stem carbon every 20 years (thinning 1); and (iii) removal of 10% stem carbon every 20 years (thinning 2), as well as a rotation period of 10, 30, 50, 100, and 150 years. Sustainable management of reforested land is addressed by implementing the so called 'Normal-forest' system (equal representation of every age class). This ensures the long term sequestration effect of reforested areas. The study shows that 3.4 Mha (Mha = Million hectare) of land, including bare land (0.7 Mha), grass land (1.2 Mha), and shrub land (1.5 Mha) can be considered as ecologically potentially suitable for reforestation. Assuming a 100 year rotation period in a 'Normal-forest' system, this shows that a total net carbon sequestration potential of 177 Tg C (10.8 Tg C in the soil and 165.9 Tg C aboveground; Teragram = 10 12 g) is possible, if all 3.4 Mha are replanted. The highest total net carbon sequestration (soil and aboveground) was evident for the Highland-wet agro-ecological zone, whereas the lowest values are typically in the Midland-dry zone. The highest net aboveground carbon sequestration was predicted for reforestations on current grass land and shrub land versus bare land, whereas the highest net soil carbon sequestration was predicted on current bare land, followed by grass land and shrub land.

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Post‐farmland conversion spatio‐temporal dynamics of net soil nitrogen mineralization and availability in a chronosequence of Zanthoxylum bungeanum plantations

Saba

Wang

et al. 2022

Land Degrad Dev

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Afforestation on cultivated farmlands causes major shifts in the nitrogen (N) cycle. The consequences of large‐scale Zanthoxylum bungeanum afforestation on spatio‐temporal patterns of soil N mineralization and inorganic N (ION) availability have not been reported. Moreover, the regulatory roles of microbial biomass and soluble organic N (MBN and SON) in the N cycle are poorly characterized in soils below 20 cm. To investigate the long‐term effects of afforestation on the governing mechanism of vertical N dynamics, a 0–100 cm soil profile was collected from a chronosequence of Z. bungeanum plantations aged 8‐year (H8), 15‐year (H15), 20‐year (H20) and 28‐year (H28), as well as adjacent farmland and abandoned‐land (28‐year) as controls in an arid valley in Southwest China. With increasing stand age, conversion of farmland to Z. bungeanum plantations significantly improved soil organic carbon, available nutrients, and all N forms. These impacts were more evident in the topsoil (0–20 cm) than in the subsoil layers. MBN and SON contents improved by 1.42‐fold and 1.34‐fold in H28, respectively, compared to H8. Net N mineralization (1.31‐fold), net nitrification rates (1.30‐fold), and total ION (1.31‐fold) content followed similar trends of increase along with the stand age. Correlation and redundancy analysis also established a positive relationship and demonstrated that increased ION availability is due to improved MBN, SON, and urease activity with the plantations age. Although the nitrate‐N content was highest in abandoned‐land, its content also increased steadily in Z. bungeanum plantations with the stand age. A relatively low ammonium/nitrate ratio (0.331) in H28 advocated improved N supply via nitrification as well as low N leaching risks from plantations. The spatial investigation provided novel insights into controls of N cycle and suggested converting farmland to Z. bungeanum plantations is a suitable approach for restoring soil N.

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Deforestation and land use strongly effect soil organic carbon and nitrogen stock in Northwest Ethiopia

Cited by 107 publications

References 66 publications

The Carbon Dynamics of Dry Tropical Afromontane Forest Ecosystems in the Amhara Region of Ethiopia

The Carbon Dynamics of Dry Tropical Afromontane Forest Ecosystems in the Amhara Region of Ethiopia

The Carbon Sequestration Potential of Degraded Agricultural Land in the Amhara Region of Ethiopia

Post‐farmland conversion spatio‐temporal dynamics of net soil nitrogen mineralization and availability in a chronosequence of Zanthoxylum bungeanum plantations

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