Management of the perennial invasive alien plant Giant goldenrod (Solidago gigantea) in the Greater vienna area
problems and challenges
Due to its fast clonal growth, Solidago gigantea competes successfully with native species. Once established, its dense stands exclude almost all other plant species. The massive distribution of S. gigantea therefore endangers native plant composition and diversity. The distribution of non-native species has consequences for evolutionary processes like hybridization, niche displacement or competitive exclusion of native species.
The, in some areas, massive dominance of invasive species renders removal of these invaders economically unaffordable and in most cases also ineffective, and therefore undesirable. Successful conservation management of invasive species and ecological restoration of riparian vegetation requires participative solutions including human land-use concepts and natural ecosystem services.
Small-scale and long-term restoration efforts are recommended.
scope and size of impact
To assess the quality of plant diversity as well as vegetation coverage and development, a grid of coordinates was placed over the research area and soil samples taken in the years 2010, 2011, 2012 and 2013. Seed bank analysis, phenological observations as well as eradication and germination experiments were performed.
The occurrence of seeds of Solidago gigantea shows a positive but not significant relationship with the total aboveground cover of the herb layer. The Shannon diversity index of aboveground plant species composition, representing the species diversity of each plot, is negatively related to increasing number of coverage of Solidago gigantea. The Pilou´s index of evenness, representing the evenness of the aboveground species composition in the herb layer of analyzed plots, is negatively related to seed density.
The vegetative development of the species Solidago gigantea starts in May very rapidly. There are no significant differences between the four observed populations. Within two weeks the first shoot emerged and the leaves develop up to 25%. The populations of Solidago gigantea are fully developed in June. By the end of August the yellowing starts and lasts until October, when the plants start to die back. The results of the observation of the generative development of Solidago gigantea show no significant differences between the populations of different sites. The first visible flower buds appear in June. In July the flower buds are clearly visible. The blooming starts in the beginning of
June and lasts until October. The maturity of fruits and the distributing of seeds start in the end of October. Analysis of the seed bank and the phenological development of invasive plant species help to specify monitoring measures.
Studies have shown a significant occurrence of invasive alien plant species in the study area. Because of the fast clonal growth,
Solidago gigantea competes successfully with native species. Once Solidago gigantea is established, its dense stands exclude almost all other plant species. Sites with open structures and sites of habitat types like tall oat grass meadows and semi-dry grasslands are mostly invaded by Solidago gigantea.
approach and activities
Active monitoring is performed with the aim of reducing the occurrence of invasive species in protected riparian areas, focused on the protection of endangered native species.
Eradication experiments correlated to phenological data optimize the management of the invasive species Solidago gigantea. The goal of achieving conservation targets requires active monitoring measures to protect hitherto non-invaded areas from biological invasion and maintain the integrity of protected natural areas for the protection of native flora.
constraints and obstacles
Besides the management of Solidago gigantea within the invaded riparian area, early diagnosis and pre-screening are important for successful control.
A further challenge is the required awareness raising and educational work to stop the distribution of invasive plant species popular in urban gardening into rural habitats.
We observe a lack of communication and information channels between the stakeholder groups: nature conservation and garden plant producers and gardeners. A legislative response currently does not exist, meaning that invasive plant species like S.
gigantea, may be legally distributed.
social dimension
The invasion of alien plant species into natural habitats cannot be prevented without an exchange of knowledge and various levels of participation.
The use of invasive species for gardening purposes should be discussed and explained rather than
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simply legally restricted. This is important for the awareness of all stakeholders of the impact of invasive species on natural habitats.
results and lessons learned
Results show an increasing impact on native species composition. When comparing germination performance to that of native plant species in the riparian habitats, Solidago gigantea shows high competitive abilities. The species richness (Shannon index) and evenness (Pilou´s index) are observed to decrease.
The growth abilities of invasive alien plant species can have controversial functions for different interests.
The invasive plant Solidago gigantea is one example of the destruction of natural habitats caused by human horticultural activities. Publicity work, scientific investigation and improvements to monitoring techniques will help to detect plants with invasive abilities earlier than was the case with Solidago gigantea.
additional information
• Richardson, D. M., P. M. Holmes, et al. (2007).
"Riparian vegetation: degradation, alien plant invasions, and restoration prospects."Diversity and Distributions 13(1): 126-139.
• Chittka, L. and S. Schürkens (2001). "Successful invasion of a floral market." Nature 411(6838):
653.
• Jakobs, G., E. Weber, et al. (2004). "Introduced plants of the invasive Solidago gigantea (Asteraceae) are larger and grow denser than conspecifics in the native range." Diversity and Distributions 10(1): 11-19.
• Meyer, G., R. Clare, et al. (2005). "An
experimental test of the evolution of increased competitive ability hypothesis in goldenrod, Solidago gigantea." Oecologia 144(2): 299-307.
• Pysek, P., K. Prach, et al. (1998). "Invasions of alien plants into habitats of Central European landscape: an historical pattern." Plant invasions:
ecological mechanisms and human responses:
23-32.
• Richardson, D. M., P. M. Holmes, et al. (2007).
"Riparian vegetation: degradation, alien plant invasions, and restoration prospects." Diversity and Distributions 13(1): 126-139.
• Gregory, S.V., Swanson, F.J., Mckee, W.A., Cummins, K.W., 1991. An ecosystem
perspective of riparian zones. BioScience 41 (8), 540-551.
• Richardson, D.M., Pyšek, P., 2006. Plant invasions: Merging the concepts of species invasiveness and community invasibility.
Progress in Physical Geography 30 (3), 409-431.