At Daiganji Temple, which was designated by Chiba Prefecture in 1935 as a natural treasure, there are records of Great Cormorants building colonies from 400 years ago. It is said that the residents carpeted with straw and sand under their nests and they made the fertilizer from the collected excrement until around 1960. The price of the fertilizer reached several thousand yen at that time as important income for the residents. This colony disappeared in 1971 because of development in the surrounding area.

Although the excrement of these birds is no longer used as resource because of the introduction of chemical fertilizers, this can be considered a piece of important wisdom toward coexistence between nature and humans that depend on a nutrient cycle between water and land.

### 2. Loss of interaction between human and ecosystem

All living organisms, including humans, are deeply interacted with each other. In order to keep interactions in good condition, it is necessary for us to maintain the Earth's environment such as land, ocean and biodiversity, which serves healthy cycle systems of water and air. These biotic interactions in ecosystems are referred to as the ecological network, in which the multi-faceted functions of biodiversity are fully performed. The ecological network provides wildlife habitat and human interaction with nature.

However, in recent years urbanization and other various human activities have caused the loss of ecosystems, fragmentation of the network, and trans-boundary environmental problems that spread through global-scale cycle systems of water and air. Photochemical oxidant causes trans-boundary air pollution, coming from the emission sources through the air and cross national borders to affect even regions thousands of kilometers away. Marine litters comes via the ocean, drifts ashore, and disperses. Here we will consider loss of healthy interactions in the earth's environment caused by human activities.

## (1) Loss of interactions in Forest Ecosystems

As seen in Chapter 1, the world’s forests have been decreasing due to human-caused effects such as commercial logging, excessive logging for wood fuel or converting forests to other purposes such as agricultural land, and due to natural causes such as forest fires.

From 2000 to 2010, each year around 13 million hectares of forests were converted to other uses. In this ten-year period, there has been an annual net reduction of 5.2 million hectares of forests, and although the speed of reduction is shifting slower than the annual 8.3 million hectares of the 1990s, it remains at a high level.

Primary forests, which are important for conservation of biological diversity, exist approximately 1.1 billion hectares around the world and are distributed mainly in North America, South America, and Southeast Asia. Primary forests are declining around the world, with approximately 88.6 million hectares of them disappearing between 1990 and 2010.

It is important to evaluate the degree of the size and connection for measuring the biodiversity of forests. In the tropical forests of Southeast Asia, the fragmentation of forests causes major impacts on the biodiversity of the

Figure 2-2-8 Annual change of forest area by country 2005-2010 (Upper Illustration) and Area of primary forest by region (Lower Graph)

Source: FAO FRA2010