Hubbard Brook Deforestation Experiment

In 1965–66, Watershed 2 at Hubbard Brook Experimental Forest was completely clear-cut and treated with herbicide to prevent regrowth. Watershed 6 was left undisturbed as a control. What happened to nutrient export in stream water?

Nitrate Concentration in Stream Water (mg/L NO₃⁻)
Watershed 6 (Control — forested)
Watershed 2 (Deforested)
Key Takeaways
🌲 Living vegetation regulates nutrient cycling — plant roots continuously absorb nitrogen and other nutrients from soil, preventing them from leaching into streams. Forests act as nutrient sponges.
📊 Removing vegetation causes a nutrient hemorrhage — after clear-cutting, nitrate export surged ~60× because decomposition continued releasing nutrients but no living roots were there to reabsorb them.
💡 Ecosystems perform critical functions beyond biodiversity — this experiment demonstrated that forests aren't just collections of species. They are biogeochemical machines that regulate water quality, nutrient retention, and soil stability.
🔬 Watershed experiments are powerful natural laboratories — by comparing a treated watershed to an undisturbed control, Likens et al. isolated the effect of vegetation removal on nutrient cycling — a foundational study in ecosystem ecology.
Developed by Dutton Lab @ University of Florida