Because of its capacity to establish dense monocultures, Solidago gigantea (giant goldenrod) is considered to be one of the most serious invasive plants threatening central European natural areas. Its prolific clonal growth and seed production facilitate rapid populatin growth, particularly in more mesic environments. While the population dynamics of this invasive plant are not well known, recent and ongoing studies are improving our understanding of the impacts of management on populations of S. gigantea. To understand the impacts of management techniques on the population dynamics, we combined data from experiments in Hungary on the demography and spread (via seeds and clonally) with new information on the efficacy of current management practices. A series of stage-based matrix models were developed for small, medium and large vegetative shoots as well as flowering adult shoots. Models were parameterized for both dryer and wetter sites, as S. gigantea survival and reproductive output varies considerably with site characteristics. The population growth rates and elasticities were examined for a variety of different management strategies.
Results/Conclusions
S. gigantea’s rapid growth was only halted if control was highly effective in reducing stem densities. Nearly a 95% reduction in stem density was required to stop population growth using mechanical control, the most common type of management used. In more productive wet environments, there were almost no small vegetative shoots in the stable age distribution, which is consistent with field observations. Population growth rates were most responsive to changes in transition rates between flowering shoots and medium vegetative shoots, and between flowering shoots and large vegetative stems. It appears that very efficient control (high stem density reduction) is required to suppress populations of S. gigantea in the long-term, and related work shows that under certain circumstances, these conditions can be met by either chemical or mechanical control.