Biodiversity, Community and Ecosystems In terrestrial ecosystems, soil is the rooting matrix in which plants grow. But, what makes for a good soil and what challenges are there for sustaining a soil for optimal plant growth? It is from this viewpoint that we have assembled the chapters in this book to describe the functional interactions of the organisms in soil that lead to soil quality. For most horticulturalists and agriculturalists, soil is a black box – the medium which supplies the plant with nutrients and water, to which fertilizers need to be added, on occasion, to maintain plant growth. However to the soil ecologist, soil is a living entity comprising of the mineral and organic matrix in which a myriad of life interacts with each other and with the plants growing there.