Ecosystem diversity encompasses the broad differences between ecosystem types, and the diversity of habitats and ecological processes occurring within each ecosystem type. It is harder to define ecosystem diversity than species or genetic diversity because the 'boundaries' of communities (associations of species) and ecosystems are more fluid. Since the ecosystem concept is dynamic and variable, it can be applied at different scales, though for management purposes it is generally used to group broadly similar assemblages of communities, such as temperate rainforests or coral reefs. A key element in the consideration of ecosystems is that in the natural state, ecological processes such as energy flows and water cycles are conserved.
The classification of the Earth's immense variety of ecosystems into a manageable system is a major scientific challenge important for management and conservation of the biosphere. At the global level, most classification systems work between the complexities of community ecology and the simplified terms of a general habitat classification. These systems use a habitat type definition with a climatic descriptor; for example, tropical moist forest, or temperate grassland. Some systems incorporate global biogeography to account for differences in biota between regions of the world which may have very similar climate and physical characteristics. The measurement of ecosystem diversity is still in its infancy. Nevertheless, ecosystem diversity is an essential element of total biodiversity and should be reflected in any biodiversity assessment.
Farmers on the island of Leyte are utilizing a range of ecosystems along a catena that can reach from primary mountain forest to the adjacent deep sea. Being a farmer during daytime and a fisherman at night requires a wide range of skills but has historically not brought about a need for the development of a sustainable land use management. This situation has drastically changed within this century of increasing human population and led to severe degradation of most accessible ecosystems. Research has been undertaken to generate new and compact widely scattered indigenous knowledge on the highly diverse flora and fauna of all major ecosystems. The results are translated into environmental awareness and pilot projects. Protected reproduction zones are recommended for the aquatic systems; efforts to sustain human food production and simultaneously preserve the biodiversity of terrestrial ecosystems and their vital functions for mankind, led to the development of a 'Closed Canopy and High Diversity Forest Farming System.' The system is aiming to replace the more destructive forms of kaingin practices, form a buffer zone around the primary forests, help maintain the water cycle of the island, and provide farmers with a stable and higher income.