Soil Erosion and Deforestation in Ecuador

Firstly I thought I’d share some short summaries of projects I’ve worked on in the past. They are quite basic in their techniques used – I was just starting out! – but I think they could be useful as a case study nonetheless.

Deforestation is a growing issue in developing countries as the demand for agricultural commodities rises. In Ecuador, the government’s subsidy based approach to agriculture and the discovery of oil has led to the country having the highest rate of deforestation in South America. Furthermore, the removal of vegetation has been identified as the leading cause of soil erosion. I chose to look at two sites in contrasting regions of the country to see how the soil has been impacted as a result of deforestation. An overview of the two sites characteristics can be seen in the table below:

napo
The Napo Region
guayas
The Guayas Region
  1: Napo 2: Guayas
Location North East of Ecuador. In the Andean and Amazon Regions. South West of Ecuador. In the Coastal region.
Soil Type Andosols Gleysols (Anthraquic) & Cambisol
Formation of soil Volcanic conditions Alluvial deposits
Characteristics of Soil type Low level of development.

High in Mercury

Cambisols: Ideal for intensive farming. Contain high levels of CEC’s.

Gleysols: ideal for rice farming,

Saturated in water.

Moderately developed

Deforestation Methods Slash and Burn Slash and Mulch
Use of land post deforestation Pasture Rice Farming

The Napo is home to one of the world’s largest deforestation fronts, the extent of which can be seen in the Landsat Images below:

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The andosols in the Napo region are vulnerable to deforestation due to the irreversible damage they obtain through desiccation and compacting. It is possible to cultivate the land for a few years before nutrients are leached and farming becomes economically unfeasible. By Wilsonbiggs - derived work from File:SOIL PROFILE.png by Hridith Sudev Nambiar at English Wikipedia., CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=46207693The quick decline can be attributed to a severe drop in organic matter entering the top layer of soil (O horizon). Furthermore, there was a 77 % reduction in CECs, which are key for nutrition, when comparing deforested areas to primary land. As a result over 60% of farmland in the region has been abandoned to pasture.

Analysis of GIS Data provided by Ecuador’s Ministry of Agriculture classifies 84% of the soils in the Napo region as not suitable for farming.  However, Article 48 of the countries land reform law allows vulnerable lands such as tropical forest to be utilised for agriculture. This intergovernmental conflict identifies a need to review land policies, particularly about protection on land with limited potential.

The Guayas has also experienced widespread deforestation, in 1963 forest cover stood at 86% however by 2000 it had deteriorated to 53%.  Yet, unlike the Napo, the Guayas has been showing resilience to deforestation.  Nutrient retention in the soil post deforestation was satisfactory, and it was possible to maintain intensive farming. The Cambisols clay structure allows for good water retention and an abundance of CECs.

Furthermore, more sustainable deforestation practices are used in the Guayas. The slash and mulch technique practised allows for much better recycling of nutrients. Whereas the slash and burn technique used in the Napo removes the mineral horizon, exposing the more developed layers to erosion.

Nevertheless, some soils in the mountainous zones of the Guayas are suffering from erosion in the form structural instability. Highlighting the importance of other factors such as topology and climatic conditions in the process of soil erosion. This loss in structure is due to lack of tree roots to hold the shallow Cambisols together and increased runoff due to vegetation loss.

As Kiage discusses deforestation ‘enhances’ soil degradation. The two sites in Ecuador show that deforestation does not always lead to soil erosion but can be a contributing factor in certain conditions. It could be argued soil degradation in Ecuador is attributed to shortfalls by the government to protect the land and invest in a national scientific base. Though this could be attributed to insufficient funds rather than lack of political will. More sustainable practices can be explored, and successful methods found in the Guayas can be applied to other suitable areas.

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