This is a classic agroforestry plot in Kilimanjaro Tanzania. A mixture of banana, avocado, some timber trees, and annual crops (at this moment, maize). There's also one sad, spindly looking coffee plant (sort of in the middle of the picture, slightly to the left of centre). The groups with whom we work here have done significant tree planting and recently I was able to do a quantitative analysis of whether all that tree planting has resulted in any measurable change or not. The graph below shows the change in vegetation--measured as an index called NDVI--over a 3 year period. What it shows is at locations where there are groups working to do tree planting, there has been an increase in vegetation over time. As you move away from the centre where the group is located, there is still a positive influence but less so with distance. At about 5 or 6 kilometres away from where these groups are located, the change in vegetation starts to become negative. This is shown in the green line. The yellow line shows what happens around a typical village in the rest of the same watershed. You can see that change at and around these villages is negative over the three years, and gets worse further away from the village.