Weeds and Biodiversity: Some Reflections

Nimal R. Chandrasena

Keywords:

: Biodiversity, colonizing species, beneficial weeds, middle-way path, weed management

Abstract:

With or without humans colonizing species will always be present on earth and continue to play vital roles in stabilizing the earth's ecosystems damaged by the teeming humanity. Therefore, humans need to 'live with weeds' and utilize their colonizing power for beneficial uses. If people well understand the valuable ecological roles and biodiversity values of colonizing species, it will influence the decisionmakers and help them develop better policies towards colonizing taxa. Agro-ecology helps us to appreciate the critical roles of colonizing taxa in Nature. Concepts such as 'beneficial weeds' and "middle-way path" to weed management allow us to re-think how we may engage in agriculture more sustainably. A change in thinking is required in Weed Science to recognize weeds, not as a production constraint in agriculture and a threat to farming, all the time. As colonizing species, they are significant bioresource assets. Where the abundance of weeds, at particular times and locations, present problems for other essential and valued human endeavours (such as food production) or natural ecosystems, they need to be appropriately managed. People have done this for millennia. The tools and techniques to do so, to the extent required, are well developed within Weed Science – a formidable discipline. An improved relationship with weeds will develop if they are understood as nothing but colonizing and pioneering taxa, which are adapted to respond to disturbances. Much like humans, they are just opportunistic species. Weeds are no more villainous than humans. The farmland biodiversity discourses, especially in Europe and the U.K., have awakened research communities to explore a more tolerant attitude towards beneficial weeds. Weedy species contribute pollination benefits for bees and food for other insects. Various fauna use them as food and shelter resources. Colonizing species also play critical roles in mitigating soil erosion, water retention, nutrient cycling and replenishment, improving soil health. Weedy congeners (relatives) also promote the evolutionary diversification and genes for hybridization with their crop relatives. Such positive contributions offset, at least partially, the losses to biodiversity that people allege weedy species cause. Biodiversity is too important for society to misunderstand it. Biodiversity is critically important for a healthy planet. Human survival on Planet Earth depends on properly interacting with biodiversity. This includes appreciating the crucial roles colonizing species play