The great cormorant Phalacrocorax carbo often have a great influence on the terrestrial ecosystem by transferring nutrients from aquatic ecosystems to land. In some areas in Japan, people used to collect nutrients transferred by the cormorants as a fertilizer and develop the techniques to maintain the colonies. As recent increase of the cormorants causes the damage on the forests of the colonies, we identified the factors affecting forest succession in the traditional guano collection and tried to evaluate their effects on the acceleration of the succession. The memories of the residents and the regional and official documents of ‘Unoyama’ colony in Aichi Prefecture showed that people scattered sand and collected guano with sand. They also mowed grasses and planted the Japanese black pine Pinus thunbergii to prevent the cormorants abandon the colony. The interpretation of the aerial photographs showed the areas of guano collecting and tree planting showed rapid forestation. Thus, collecting guano with sand and planting the pine trees would function as a removal of surplus nutrients and an acceleration of the early succession each other.