Abstract: atural ecosystems support life, contribute to human welfare, and provide essential conditions and services for civilization. The contributions and benefits from natural ecological systems to human societies are ecosystem services, which include: production of natural goods, biodiversity maintenance, climate regulation, regulation of hydrological flows and water supply, mitigation of droughts and floods, cycling and moving nutrients, generation and preservation of soils and renewal of their fertility, detoxification and decomposition of wastes, pollination and seed dispersal, pest control, maintenance of conditions for both mental and physical health and healing of human beings, provision of aesthetic, intellectual, and spiritual stimulation. The services flowing from natural ecosystems are enormous and indispensable for economy and welfare, but have been greatly undervalued by society, partly because they are not traded in markets and people are rarely ware of the role and importance of these services. In market-driven societies, the valuation of ecosystem services is useful to support more ecologically conscious decision-making. Identification and monitoring of ecological processes that generate ecosystem services are much needed. Human activities already have altered physical, chemical, biological and geographic attributes of the Earth profoundly and have been impairing the flow of ecosystem services on a large scale. We are facing a great challenge to maintain a sustainable society that is ecologically sound, economically feasible, socially just and peaceful. Ecologists should work closely with public and policy-makers to answer this challenge.

Key words: Ecosystem services, Nature, Human society