Estimating the Benefit of Early Control of All Newly Naturalised Plants

📖 The Scoop

Early eradication of weeds is preferable to attempting to control them when they are well-established, and becoming a problem. But when a plant is newly naturalised, we often do not know if it will eventually become a weed. In this study, we compare the cost effectiveness of removing all newly naturalised plants early or delaying action until they prove to be weeds. We obtained data from 58 Department of Conservation weed control projects around New Zealand and used these data to compare the typical cost for controlling a weed infestation at two stages of invasion: early stage small infestation, and late stage large infestation. We also modelled weed spread using different scenarios of plant growth rate and dispersal plus typical time estimates for weed infestations to spread. We then analysed the control costs at 5, 10, 20 and 40 years from establishment, to predict the cost implications of delaying weed control. Our data suggest that, early on, while an infestation is small (only a few plants or plants covering an area up to 400 m²), all individuals can be easily removed for a minimal cost--an average of $1090. By contrast, if control is postponed until a later stage (when the infestation is widespread or dense) it is, on average, 40 times more expensive than early removal. Furthermore, it is shown that if a plant's weed potential is unknown, its early removal will still be beneficial if removal can be achieved for less than $7000. Once a weed disperses from its initial establishment point, the costs of control increase dramatically, largely because of the burgeoning cost of searching for individual plants.

Genre: No Category (fancy, right?)