In general, as the demand for landscape services increases in response to increasing population pressure, there is a decline in many of the regulating and supporting ecosystem services. Degraded ecosystems generally do not produce the necessary goods and services to support human populations. In classic Bosrupian theory people will eventually invest in their land to rehabilitate its productive capacity. While there is considerable knowledge about rehabilitating the productive capacity of degraded lands, far less known about rehabilitating the regulating and supporting ecosystem services.
Large areas of SubSaharan Africa are currently degraded, yet its people are often too poor to purchase the necessary inputs needed for rehabilitation, resulting in a positive feedback loop that creates resilient poverty traps. Here we explore the role of trees in rehabilitating ecosystem services in landscapes. Among the questions that are addressed are: what proportion of the landscape needs to be covered with trees to provide different ecosystem services? Where on the landscape and in what configuration do the trees need to be situated? What investments are needed to do so? And, how to pay for these investments.