A study in New Zealand looked at a raised bog and found that it is likely ombrotrophic, meaning it gets its water and nutrients mainly from rain. The plants in the bog are similar to those in other ombrotrophic bogs in the country. By looking at the pH levels and the ratio of calcium to magnesium, researchers could tell the difference between the bog and a nearby fen. The change in pH and calcium/magnesium ratio seems to trigger a shift in the types of plants that grow in the bog.