A juice company dumped orange peels in a national park. This is what it looks like today.

In the mid-1990s, 1,000 truckloads of orange peels and pulp were unloaded onto a barren pasture in Costa Rica's Área de Conservación Guanacaste. Sixteen years later, a Princeton-led survey found a 176 percent increase in aboveground biomass within the 3-hectare studied area, with the barren land now covered in lush, vine-laden forest.

The area was barren pasture, not previously thriving forest; the study documents this one 7-acre plot over 16 years and does not assess longer-term stability or ecosystem complexity.