The Effect of Deforestation on Watershed Ecosystems

By: Danwoo Kim

April 7, 2025

Introduction

Deforestation is a widely known crisis resulting from human need for raw materials for industrialization. This has led to a steady increase cutting of trees to keep up with growing industrialization and production. While significant efforts have been made to “save the trees” through planting trees, limiting deforestation from companies, and fighting wildfires, it remains a prominent issue that is linked to water scarcity. The natural flow of water is continually disrupted through deforestation in multiple aspects, particularly in watershed environments.

Tractor deforestation.

The Problem with Deforestation

According to a study conducted in 2022, when deforestation is widespread and it affects precipitation, it is found that “deforestation causes reduction of river flow.” [2] A reduction in the flow of the river due to deforestation leads to several detrimental effects. Pollutants in the water system are not cleared quickly and begin to build up, obstructing the flow of the water and changing its path in watershed ecosystems as more and more water is polluted. It can also increase the content of certain nutrients, such as nitrogen in the water, along with a reduced content of dissolved oxygen, leading to algae blooms and reducing biodiversity. Water temperature is also increased due to a slowing down of the speed of the flow of the water, leading to more exposure to heat (sunlight) and less capability to cool. The unclean and now potentially pathogen thriving atmosphere of the water due to higher temperatures can lead straight to human civilizations and thus lead to the spread of viruses. 

Deforestation of natural ecosystems turning into managed civilizations also “threatens global soil biodiversity and its capacity to provide ecosystem services” [3], which then affects the soil’s ability to regulate water quality. As tree systems and forest roots bind soil and land mass together, they maintain the proper regulation of water flow and nutrient allocation. Deforestation disrupts this process, and it can also disrupt habitats for microbial water-based organisms that aid in the regulation of water to prevent pathogen growth. With 10 million hectares of land experiencing deforestation annually in 2024 [1], this number will only continue to steadily increase, and solutions must be found to prevent the negative impacts that deforestation is having on water quality and regulation in watershed ecosystems. 

Potential Solutions

Some potential solutions have already been taken to address deforestation and its effects on watershed ecosystems. Of course, reforestation through local nonprofits or national/international organizations is influential in the gradual replanting of lost trees due to deforestation. Afforestation also plants trees in places previously lacking such plants, allowing for the regulation of the water cycle and preventing soil erosion, which leads to cleaner water in general. 

Legal policies concerning the deforestation of trees should also be made stronger and perhaps even stricter, as such problems are still occurring even with current laws. As for people living their daily lives, even expanding green space, whether that be through joining a team planting trees or planting your own botanical garden, can aid in the healthy regulation of water, allowing clean and sustainable resources for the future. Together, these solutions can significantly mitigate the influence of deforestation.

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References:

1. Denchak, M., & Mackenzie, J. (2024, November 25). Deforestation and Forest Degradation: The Causes, Effects, and Solutions. Nrdc.org. https://www.nrdc.org/stories/deforestation-forest-degradation-causes-effects-solutions

2. Posada-Marín, J. A., & Salazar, J. F. (2022). River flow response to deforestation: Contrasting results from different models. Water Security, 15, 100115. https://doi.org/10.1016/j.wasec.2022.100115

3. Qu, X., Li, X., Bardgett, R. D., Yakov Kuzyakov, Revillini, D., Sonne, C., Xia, C., Ruan, H., Liu, Y., Cao, F., Reich, P. B., & Delgado-Baquerizo, M. (2024). Deforestation impacts soil biodiversity and ecosystem services worldwide. Proceedings of the National Academy of Sciences of the United States of America, 121(13). https://doi.org/10.1073/pnas.2318475121