Why is it necessary for ecosystems to be managed by humans? This is a good question because ecosystems have existed naturally, with various living species, and maintained various systems long before human society was built up. Therefore it would be better if humans did not interfere with natural ecosystems at all. 

Here, an explanation will be given about "ecosystem-based management " or "ecosystem management". These expressions make it sound like natural ecosystems are under the control of humans, but is that actually necessary? The word "management" is not "control" but "management". "Ecosystem-based management" is applied science to conserve ecosystems that have a complicated relationship with human society based on the latest knowledge in scientific ecology. 

The most important thing in the past used to be managing natural resources in a way that maximized yields. Eventually, we learned to balance production and consumption, in order to avoid exploiting our resources without any restriction. However ecosystem services and biodiversity were never a primary concern, provision services always took priority. 

The science of "conservation biology" started to gain popularity in the 1980's, when the importance of conserving biodiversity was recognized. With this new view emerging it was remarkably improper to only consider the quantity of resources. Especially from the end of the 20th century to the beginning of the 21st century, there was much more support and clarification of the importance of diversity to maintain ecosystem services that human society receives (Millennium Ecosystem Assessment 2005). This knowledge lead to the realization that perhaps the best way to manage an ecosystem is to respect its inherent natural processes. 

The table below shows the change from the classical views of traditional resource management (so-called "steady-state resource management") to the new views on ecosystem-based management. However, in spite of the development of ecosystem-based management paradigm, many environmental policies still focus only on "balance of nature ", and try to eliminate variability and changes. (Mori 2011a, 2011b). 

An ecosystem is very diverse, so predicting when and where changes will happen is difficult in present science (unpredictability). What makes it even harder is that changes beyond our expectations are happening all the time (uncertainty). Before it was thought that these natural systems called ecosystems had a stable unchanging condition (equilibrium concept), however as ecology progressed it was getting clearer that these natural systems are full of uncertainty and unpredictability (Non-equilibrium concept). 

In addition to adaptive management, there is considerable concentration on co-management when it comes to ecosystem-based management. In co-management, various stakeholders can participate in decision-making equally. It is not a management system based on a top-down system from governments or scientists, or a system where governments make final decisions. 

As it is currently thought impossible to separate humans or society from ecosystems (Chapin et al. 2009), it is necessary to explore sustainability to maintain ecosystem services that human society permanently receive while paying special attention to complex interactions between society and nature. This is "ecosystem-based management".

Table. Ecosystem-based management as a paradigm shift (UNEP/GPA 2006).

References 

Chapin, F.S. III., Kofinas, G.P., Folke, C. (2009) Principles of ecosystem stewardship. Resilience-based natural resource management in a changing world. Springer, New York, USA. 

Millennium Ecosystem Assessment (2005) Ecosystems and human well-being: current state and trends: Findings of the Condition and Trends Working Group. Island Press, Washington D.C., USA. 

Mori, A.S. (2011a) Ecosystem management based on natural disturbances: hierarchical context and non-equilibrium paradigm. Journal of Applied Ecology 48:280-292. 

Mori, A.S. (2011b) Making society more resilient. Nature 484:284.