What are environmental impacts of primitive subsistence farming?

Primitive subsistence farming, including practices like shifting cultivation (slash‑and‑burn) and primitive tillage, has several environmental impacts due to its heavy reliance on natural ecosystems and absence of scientific soil and forest management. While it traditionally sustains rural communities, increasing population pressure and shorter fallow cycles have intensified its negative effects.

Major Environmental Impacts

1. Deforestation and Habitat Loss

• Farmers clear large forest areas by cutting and burning trees to create temporary agricultural fields.
• Continuous clearing reduces forest cover and destroys wildlife habitats, particularly in biodiversity‑rich regions such as Northeast India and the Western Ghats.
• Loss of forest vegetation disrupts the carbon cycle and contributes to climate change through increased carbon dioxide emissions.

2. Soil Erosion and Nutrient Depletion

• Burning removes vegetation cover, exposing topsoil to rain and wind erosion.
• The ash initially increases fertility, but nutrients are quickly leached out or eroded, making the soil infertile after a few seasons.
• Repeated clearing accelerates land degradation and desertification, especially on hilly slopes.

3. Loss of Biodiversity

• Replacement of diverse forest ecosystems with single‑crop fields leads to declining plant and animal diversity.
• Soil microbial biodiversity also reduces, affecting processes like nutrient cycling, pest control, and water purification.

4. Decline in Water Quality and Catchment Function

• Removal of vegetation reduces groundwater recharge and increases runoff, decreasing river flow during dry seasons and increasing flooding risks during monsoons.
• Erosion and ash runoff cause siltation in rivers and reservoirs, harming aquatic ecosystems.

5. Greenhouse Gas Emissions

• Burning of vegetation releases carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), contributing to global warming.
• Even though individual fires are small, cumulative emissions across shifting cultivation zones are significant.

Secondary Impacts

• Reduced soil organic matter weakens long‑term agricultural productivity.
• Invasive weeds often colonize fallow land, altering the natural regeneration process.
• Shorter fallow cycles—driven by population pressure—prevent full forest recovery, making ecosystems increasingly fragile.

Balanced Perspective

When practiced traditionally with long fallow periods (10–20 years), primitive subsistence farming was ecologically sustainable.
However, modern demographic and economic pressures have shortened fallow cycles (to 2–5 years), turning the system into one that degrades rather than renews the environment.