Coastal forests in Tanzania have a lot of different plant species. Researchers wanted to figure out which factor best shows how diverse the plants are in three specific forests. They looked at the number of species, how evenly they were spread out, and how many there were in each area. They found that evenness of species was the most important factor in determining plant diversity, while the number of species didn't matter as much. This means that having a balanced mix of different plants is key to understanding the value of these forests for conservation.