Agroecological Benefits from Weeds

Abstract

We begin by stating a basic premise: that weed science must be fundamentally concerned, like all of agricultural science, with the imperative of sustainability. This concern underlies the mounting questions about the profitability, long-term efficacy, and environmental safety of the discipline’s historical focus: herbicidal management of weeds (i.e., “plants out of place”). Herbicide-based approaches are currently relied upon in managed ecosystems of many sorts: e.g., farms, forests, and waterways (Cousens and Mortimer, 1995; Sheley et al., 1997). Our own assessment is that economically, ecologically, and agronomically sustainable weed management systems cannot be attained by current concepts and means of weed management. In addition to concerns for agricultural sustainability, there is rapidly-growing recognition that biological invasions by plants are a troublesome component of global change (i.e., large-scale detrimental changes in ecological systems that provide “life-support” functions to humanity; Daily, 1997; Mack et al., 2000). Weed scientists are actively considering how they can contribute to the scientific and social response to this problem. The challenge is to expand the scope of weed science from current emphases on herbicides and field-crop agroecosystems to the larger work of coping with invasive plants in ecosystems of all kinds, including areas that are managed to preserve their “natural” qualities. Below, we argue that progress towards more expansive and sustainable notions of weed management will require new theories of weeds and weed management that are based on a broader view of the agroecological roles of weeds.