(from the Greek biosis:living and sym:together) refers to the myriad ways in which organisms interact within a community, often cooperatively. Ecologists studying these interactions have revealed just how interconnected and interdependent communities are. Soil ecologists have documented within a gram of soil entire ecosystems of interactions amongst flora and fauna, usually too small to the naked eye, contribute significantly to soil fertility. Healthy soils depend on these microscopic ecosystems replete with symbiotic interactions, which in turn contribute to healthier above ground ecosystems, including agricultural crops. Farming practices that support soil symbioses can increase productivity.