Expansive shrubs: Expansion factors and ecological impacts in northern Ethiopia

Haile, Mebrahtu; Birhane, Emiru; Rannestad, Meley Mekonen; Adaramola, Muyiwa S.

doi:10.1016/j.jnc.2021.125996

Cited by 12 publications

(12 citation statements)

References 45 publications

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“…e considerable difference in total biomass carbon between the uninvaded and adjacent invaded vegetation conditions could be explained in two ways. First, an increase in abundance and expansion of the expansive species to new areas in Desa'a forest was facilitated by anthropogenic disturbances like burning, overgrazing, and overharvesting of the PNV for fuelwood, fencing, construction materials, agricultural equipment, and charcoal making [23,30]. Expansion of the expansive species in the area could have resulted in lower carbon stocks due to their lower DBH.…”

Section: Biomass Carbon Stocksmentioning

confidence: 99%

“…Furthermore, expansion of expansive species can result in various impacts on nutrient exchanges, as expansive species commonly have stronger growth potentials [1]. However, they could have positive or negative impacts on soil fertility [3,23]. Seitz et al [24] indicated that changes in the composition of plant communities directly influence soil characteristics, with soil processes responding to the composition of the plant community.…”

Section: Introductionmentioning

confidence: 99%

“…e two expansive shrubs in this study, Cadia purpurea (C. purpurea) and Tarchonanthus camphoratus (T. camphoratus), are perennial native shrubs expanded extensively in Desa'a dry Afromontane forest (hereafter Desa'a forest) in northern Ethiopia. e study by Haile et al [23] indicated a shift in woody plant species composition, and the impacts on plant diversity and regeneration status followed the expansion of expansive shrubs in the forest. Population structure indicators like diameter, height, and mean basal area of the plant species were also declined with the expansion of the expansive shrubs [23].…”

Section: Introductionmentioning

confidence: 99%

“…e study by Haile et al [23] indicated a shift in woody plant species composition, and the impacts on plant diversity and regeneration status followed the expansion of expansive shrubs in the forest. Population structure indicators like diameter, height, and mean basal area of the plant species were also declined with the expansion of the expansive shrubs [23]. Besides, despite the species and site-specific nature of the expansive plant species, both negative and positive impacts of expansion on different ecological aspects have been reported [3,5,13,15,19].…”

Section: Introductionmentioning

confidence: 99%

“…Besides, despite the species and site-specific nature of the expansive plant species, both negative and positive impacts of expansion on different ecological aspects have been reported [3,5,13,15,19]. e spatial distribution [26], the expansion factors, and the impacts of both expansive shrubs (C. purpurea and T. camphoratus) on plant diversity, regeneration, and structure [23] were previously evaluated. However, the impacts of the two expansive species on carbon stock and soil characteristics have not been reported yet, while it is important that they are documented.…”

Section: Introductionmentioning

confidence: 99%

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Carbon Stock and Soil Characteristics under Expansive Shrubs in the Dry Afromontane Forest in Northern Ethiopia

Haile

Birhane

Rannestad

et al. 2021

International Journal of Forestry Research

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Increased presence of expansive plant species could bring about various ecological influences on biomass carbon, soil organic carbon, and the physical and chemical properties of the soils. However, their impacts on these ecological parameters could differ due to a wide range of life forms, plant communities of the invaded ecosystems, and abiotic conditions. This work was conducted to examine the impacts of Cadia purpurea and Tarchonanthus camphoratus cover on carbon stock in vegetation and soil and soil physicochemical properties in Desa’a forest, northern Ethiopia. Vegetation and soil data were collected from a total of 150 sampling plots (size 20 m × 20 m) from uninvaded and invaded vegetation conditions. The soil samples were collected from topsoil (0–15 and 15–30 cm) of the uninvaded and invaded vegetation conditions. The statistical difference in carbon stock and soil characteristics P < 0.05 of both invaded and uninvaded vegetation conditions were tested using an independent t-test using an R-software. The mean above- and below-ground biomass carbon stocks of the uninvaded vegetation condition (17.62 Mg·C/ha and 4.14 Mg·C/ha, respectively) were found to be significantly higher than those of the invaded vegetation condition (4.73 Mg·C/ha and 1.11 Mg·C/ha, respectively). The mean soil organic carbons (SOC) were significantly higher P < 0.01 in the uninvaded (122.83 Mg·C/ha) than in the invaded (90.13 Mg·C/ha) vegetation condition. The total carbon stock estimates were significantly higher P < 0.01 in the uninvaded vegetation condition (144.59 Mg·C/ha) than in the invaded vegetation condition (95.97 Mg·C/ha). Furthermore, the result revealed that most of the soil characteristics were significantly lower P < 0.05 under the expansive shrubs invaded vegetation conditions except for significantly high sand content P < 0.05 . Silt, nitrogen, phosphorus, calcium, copper, and zinc did not significantly change with the cover of the expansive shrubs. Our results suggest that increased presence of the expansive species decreased carbon trapping and affected most of the soil nutrients within the forest. Hence, to enhance the carbon storage potential and to maintain the soil nutrient status of the forest, proper conservation, monitoring, and management of the existing PNV and controlling a further expansion of the expansive shrubs are required. Further studies will be required on the factors responsible for the difference in carbon stocks and soil nutrients in each vegetation condition in addition to the impacts of the expansive shrubs expansion.

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Section: Biomass Carbon Stocksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Carbon Stock and Soil Characteristics under Expansive Shrubs in the Dry Afromontane Forest in Northern Ethiopia

Haile

Birhane

Rannestad

et al. 2021

International Journal of Forestry Research

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Anthropogenic Impact on Plant Biodiversity

Yaynemsa

2022

Plant Biodiversity Conservation in Ethiopia

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Slope aspect of a mountainous grassland landscape shapes the structure of an encroaching shrub (Euryops floribundus N.E. Br): insights from communal grazing sites located at varying distances from rural homesteads

Gxasheka,

Dlamini

2024

COMMUNITY ECOLOGY

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Mountainous grassland landscapes are severely threatened by the proliferation of shrub encroachment. So far, it remains unclear though how slope aspect coupled with land disturbances linked to the proximity of homesteads to communal grazing sites affects the distribution, density and structure of the encroaching shrubs in these grassland ecosystems. In this study, we investigated the role that slope aspect plays in determining the density and structure of an encroaching shrub species Euryops floribundus N.E. Br in three communal grazing sites located at varying distances from rural homesteads in a semi-arid mountainous grassland in the Eastern Cape Province of South Africa. Three sites were strategically chosen in Cala communal grazing lands in an encroached mountainous grassland landscape that depicted north and south-facing slope aspects. The selected sites were Tsengiwe; a site located in close proximity to homesteads at a distance of less than 100 m, Upper Mnxe situated at an intermediate distance ranging from 200 to 800 m away from homesteads and Manzimdaka, which was located furthest from homesteads at a distance greater than 1600 m. In each site and corresponding slope aspect, the density and structure of the shrub E. floribundus were evaluated on 36 randomly distributed plots, yielding a total of 108 plots across all sites. We found that shrub density was significantly higher (50%) on the north-facing slope compared to the south-facing slope in Tsengiwe, the site located near homesteads. Shrub height was significantly higher (53 and 17%) on the north-facing slope compared to the south-facing slope at Upper Mnxe and Manzimdaka, which were located at intermediate and furthest distances from the homesteads. Notably, shrub height was significantly lower (37%) in the north-facing slope compared to the south-facing slope in Tsengiwe. Following a similar pattern to shrub height, total stem number was significantly higher (20 and 85%) in the north-facing slope compared to the south-facing slope at Upper Mnxe and Tsengiwe, respectively. Shrub crown area was higher (33 and 11%) in the north-facing slope compared to the south-facing slope at Upper Mnxe and Manzimdaka, respectively. A strong positive relationship was established between the height of shrubs and their longest crown diameter, shortest crown diameter and shrub crown area across all sites, suggesting that the investigated shrub species E. floribundus employs its structural characteristics to survive, and thrive and this was more evident in the north-facing slope. The results highlight the importance of considering the proximity of homesteads into account in ecological studies, and puts emphasis on improved understanding of the vegetation patterns shaped by shrub encroachment in mountainous grasslands, which is crucial in the development of effective land management strategies.

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Expansive shrubs: Expansion factors and ecological impacts in northern Ethiopia

Cited by 12 publications

References 45 publications

Carbon Stock and Soil Characteristics under Expansive Shrubs in the Dry Afromontane Forest in Northern Ethiopia

Carbon Stock and Soil Characteristics under Expansive Shrubs in the Dry Afromontane Forest in Northern Ethiopia

Anthropogenic Impact on Plant Biodiversity

Slope aspect of a mountainous grassland landscape shapes the structure of an encroaching shrub (Euryops floribundus N.E. Br): insights from communal grazing sites located at varying distances from rural homesteads

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