Since the term is defined from a strictly anthropocentric point of view, depending on the type of human activity it refers to, the same species can be weedy in one environment and desirable in another. For example, grasses that make up the lawn on a golf course are hot, but a spontaneously growing mint plant would be considered a weed. And on the contrary, in a mint crop for pharmacological use, lawn grasses would be weeds.
The study of weeds
Due to their importance in agriculture and horticulture, weeds or weeds have been the subject of study, primarily aimed at discovering methods for their eradication. However, their ecological characteristics also make them excellent for studying adaptation and evolution.
Weeds have a ruderal behaviour; that is, they can develop in habitats altered and disturbed by human activity. In addition to crop fields, parks, and gardens, they colonize roadsides and paths, burned areas, abandoned fields, and even the streets and houses of uninhabited towns.
They tolerate high concentrations of nutrients in the soil and grow and reproduce rapidly. Its seeds are readily dispersed, can take root in cracks with a small substrate volume, and are resistant to adverse conditions. They can remain dormant in the soil for months or years until the environment is correct and germinate.
About their advantages as an object of study, it is possible to document their history in a specific geographical area and to have evidence of their recent evolution under human influences that can be identified.
Weed or invasive grass?
Confusion between an invasive weed and a weed is not uncommon. Many invasive species behave like weeds, and many of the weeds are indeed invasive. However, the differences between the two, although they may seem subtle, are not trivial matters.
An invasive species, by definition, is an exotic species transported by the human hand to a new ecosystem, where it has been released, survived, formed reproductive populations, and expanded, colonizing new environments different from those it introduced.
Invasive plants have many traits of weeds and very often behave like weeds. But other invasive species do not have that weedy behaviour of colonizing land for human use but prefer to colonize natural environments.
On the other hand, some weeds are neither invasive nor exotic. Native wild species only try to recover the environment taken from them by eliminating a natural ecosystem to turn it into a wheat field, a pasture area or a golf course.
The ‘good herbs’
‘weed’ implies negative connotations that respond only to a very restricted socioeconomic aspect. Weed plants indeed have a particular impact on agriculture; they are unpleasant in parks and gardens and uncomfortable in recreational areas.
But those negative aspects do not justify his lousy name or fame. Weed plants, from an ecological point of view, are of great importance. Their presence and dynamics positively impact the functioning of ecosystems and the services they provide.
On the one hand, their high tolerance to soils highly managed by man makes them essential for recovering the natural environment in the process of ecological succession. In addition to acting as primocolonizing species of the disturbed environment, they also decontaminate it and optimize it for the subsequent colonization of larger and longer-lasting species. Furthermore, weed communities are usually made up of multiple species that coexist and compete, enriching the environment’s biodiversity.
Their rapid growth and reproduction added to the fact that most of these plants form communities renewed yearly, making them a suitable mechanism for capturing carbon that is later stored in the soil.
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