Lines in the landscape

Ditches (linear constructions which store and/or move water where humans prefer it to go), via irrigation, drainage, and power, have helped drive the development of human societies. Now, ditches and other linear channels, typically carrying water, are numerous and found on every continent. Their form varies widely with use, which includes land drainage, irrigation, transportation, and boundary marking. Ditches support and shape biogeochemical cycles, biotic communities, and human societies, at multiple spatiotemporal scales. However, ditches are frequently overlooked by researchers in many disciplines. Here, we review the largely unrecognized role that ditches play in environmental processes and human societies. The effects of ditches can be both positive (e.g., biodiversity refuges, water for food production, nutrient retention) and negative (e.g., greenhouse gas emissions, dispersal of pollutants). We call for future management to consider and enhance the multifunctional role that ditches can deliver at the landscape-scale.