Effects of removing Cynodon dactylon from a recently abandoned agricultural field

An understanding of ecosystem response to the removal of a dominant non-native species is critical for planning control or eradication efforts. The objective of this study was to evaluate the response of recently abandoned agricultural fields in south-eastern Arizona, USA to the removal of Cynodon dactylon, a dominant perennial rhizomatous grass. C. dactylon was removed from treatment plots using glyphosate herbicide. Repeated application of glyphosate to C. dactylon did have a significant impact on the cover of C. dactylon and in the community composition of the treated plots. However, patterns observed in this study were similar in both control and treated plots, suggesting that the response of the system to the removal of C. dactylon was nested within larger changes the entire system was experiencing during the time of the study. The short-term, dynamic response to herbicide treatment seemed to be mediated by the amount and timing of precipitation. Additionally, though C. dactylon removal via herbicide treatment was effective, undesired effects including increases in other non-native, noxious species were observed. The results demonstrate that control of C. dactylon would likely be possible and cost-effective for this site. However, removing C. dactylon apparently created conditions conducive for other opportunistic species to increase. The decision to undertake a large-scale eradication effort should weigh the benefits of C. dactylon removal against the potential increase in other undesirable species.