Exploring Ecosystem Health Beyond Greening Patterns: Insights from Somalia

When we think about environmental challenges in Africa, one might think of an expanding Sahel desert that slowly eats away from pasture and forest lands. However, the reality is more nuanced than this narrative. While desertification is a concern in many parts of the world, recent research paints a different picture across Africa and in the Sahel region.

Contrary to popular belief, the Sahel and West Africa have experienced a general ecosystem greening in the last three decades attributed to increased rainfall levels, elevated levels of atmospheric CO2, and improved fire management practices.¹^,² But as we delve deeper into the complexities of ecosystem dynamics, it becomes clear that the story doesn’t end with just greener landscapes.

Ecosystem health is multifaceted, encompassing a range of factors. While green ecosystems are associated with a high vegetation productivity and carbon update, it can also indicate an ecosystem with a lower livestock grazing capacity than a browning landscape.³ This has to do with the fact that woody vegetation reflect a stronger greening signal than herbasceous vegetation, but it has a lower grazing capacity than herbasceous vegetation. This shows the multi-dimensionality of ecosystem functioning and stresses the need for comprehensive ecosystem monitoring appraoches. In this blog we will look at the case study of Somalia and we will discuss some ecological trends that have occured here in the last two decades.

Somalia has experienced a greening trend (Figure 1), consistent with a broader pattern observed across the African continent. This trend is particularly evident in the northern regions of the country and certain parts of the southwest. Additionally, some areas surrounding river basins, where water availability is relatively abundant, have shown significant greening over the past two decades.

However, not all regions are experiencing this greening surge. Coastal areas, in particular, have witnessed a decline in vegetation density. For instance, around major urban centers like Mogadishu and Kismaayo, there has been a notable decrease in vegetation density between 2000 and 2023. These findings shed light on spatial dynamics of vegetation trends but they do not provide insights in the type of vegetation increases or declines.

Figure 1: Average yearly vegetation (EVI) change in Somalia between 2000-2023.

A more comprehensive picture of the ecoststem health in Somalia is displayed in Figure 2 where we can dissect between tree presence and land health patterns. Interestingly, over the period from 1995 to 2021, Somalia’s tree cover and soil organic carbon (SOC) have remained relatively stable, while soil erosion has increased by 10 percentage points, as highlighted in Figure 3.

There are large differences across the different regions of Somalia. In the arid landscapes of Northern Somalia, tree presence and land health has remained stable at low levels. Moving to the mid-west, we observe a contrasting scenario of increased tree densities and decreased land health during the past two decades. This increase in tree cover might be related to reduced human ecosystem pressure in the region, due to the presence of Al-Shabaab that have displaced communities from the area. This could have allowed trees to thrive while land health deterioated.

While the increase in tree cover may initially seem like a positive development, it’s essential to recognize that this is not always beneficial. In fact, there is mounting evidence suggesting that much of the tree cover expansion in Africa is driven by invasive species encroachment (Venter et al., 2018). Invasive trees and plants can create the illusion of a green, lush and healthy ecosystem while actually causing significant harm by degrading soil quality and depleting water sources. Therefore, invasive specie enchrochent may also be driving the increased tree presence but decreased land health in some areas. More specifically, invasives may have contributed to the high soil erosion levels that Somalia has expierenced between 1995-2021 (Figure 3).

Conversely, in the Southern coastal region, we witness a different pattern. In 1995, this area boasted a distinct belt along the Southern coast of high land health and tree cover. However, by 2021, there has been a noticeable decrease in tree cover, with land health also showing signs of deterioration. This shift may be linked to increased urbanization and settlement activity, potentially driven by conflicts in other parts of the country.

Figure 2: Ecosystem health in Somalia expressed by tree presence and land health (soil organic carbon and erosion).

These findings underscore the complex interplay of environmental factors and human activities shaping Somalia’s ecosystems. By dissecting these trends, we can better understand the challenges facing different regions and develop targeted strategies for sustainable land management and conservation efforts. Yet, we have also seen the tree cover is not always related to a healthy ecosystem. Therefore, it’s crucial that we not only monitor the presence of trees but also pay close attention to the specific species involved. By doing so, we can gain a more nuanced understanding of the ecological changes taking place.

It’s important to note that this blog does not aim to provide definitive conclusions on ecological issues. Rather, its purpose is to highlight the complexities inherent in ecosystems and emphasize the need to consider multiple perspectives when seeking to understand them. By embracing this approach, we can work towards a more holistic understanding of our ecosystems and develop more effective strategies for its conservation and management.

Figure 3: Distribution of Soil Organic Carbon (SOC), soil erosion and tree cover across Somalia in 1995 and 2021.

Footnotes

Zhu, Z., Piao, S., Myneni, R.B., Huang, M., Zeng, Z., Canadell, J.G., Ciais, P., Sitch, S., Friedlingstein, P., Arneth, A., Cao, C., Cheng, L., Kato, E., Koven, C., Li, Y., Lian, X., Liu, Y., Liu, R., Mao, J., Pan, Y., Peng, S., Peuelas, J., Poulter, B., Pugh, T.A.M., Stocker, B.D., Viovy, N., Wang, X., Wang, Y., Xiao, Z., Yang, H., Zaehle, S., Zeng, N., 2016. Greening of the Earth and its drivers. Nature Climate Change 6, 791–795. URL: https://www.nature.com/articles/nclimate3004, doi:10.1038/nclimate3004.↩︎
Venter, Z.S., Cramer, M.D., Hawkins, H.J., 2018. Drivers of woody plant encroachment over Africa. Nature Communications 9, 2272. URL: https://www.nature.com/articles/s41467-018-04616-8, doi:10.1038/s41467-018-04616-8.↩︎
D’Adamo, F., Ogutu, B., Brandt, M., Schurgers, G., Dash, J., 2021. Climatic and non-climatic vegetation cover changes in the rangelands of Africa. Global and Planetary Change 202, 103516. URL: https://linkinghub.elsevier.com/retrieve/pii/S0921818121001016, doi:10.1016/j.gloplacha.2021.103516.↩︎