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Invasiveness does not predict impact: response of native land snail communities to plant invasions in riparian habitats.

ABSTRACT: Studies of plant invasions rarely address impacts on molluscs. By comparing pairs of invaded and corresponding uninvaded plots in 96 sites in floodplain forests, we examined effects of four invasive alien plants (Impatiens glandulifera, Fallopia japonica, F. sachalinensis, and F.× bohemica) in the Czech Republic on communities of land snails. The richness and abundance of living land snail species were recorded separately for all species, rare species listed on the national Red List, and small species with shell size below 5 mm. The significant impacts ranged from 16-48% reduction in snail species numbers, and 29-90% reduction in abundance. Small species were especially prone to reduction in species richness by all four invasive plant taxa. Rare snails were also negatively impacted by all plant invaders, both in terms of species richness or abundance. Overall, the impacts on snails were invader-specific, differing among plant taxa. The strong effect of I. glandulifera could be related to the post-invasion decrease in abundance of tall nitrophilous native plant species that are a nutrient-rich food source for snails in riparian habitats. Fallopia sachalinensis had the strongest negative impact of the three knotweeds, which reflects differences in their canopy structure, microhabitat humidity and litter decomposition. The ranking of Fallopia taxa according to the strength of impacts on snail communities differs from ranking by their invasiveness, known from previous studies. This indicates that invasiveness does not simply translate to impacts of invasion and needs to be borne in mind by conservation and management authorities.

SUBMITTER: Horackova J

PROVIDER: S-EPMC4169606 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Invasiveness does not predict impact: response of native land snail communities to plant invasions in riparian habitats.

Horáčková Jitka J Juřičková Lucie L Šizling Arnošt L AL Jarošík Vojtěch V Pyšek Petr P

PloS one 20140919 9

Studies of plant invasions rarely address impacts on molluscs. By comparing pairs of invaded and corresponding uninvaded plots in 96 sites in floodplain forests, we examined effects of four invasive alien plants (Impatiens glandulifera, Fallopia japonica, F. sachalinensis, and F.× bohemica) in the Czech Republic on communities of land snails. The richness and abundance of living land snail species were recorded separately for all species, rare species listed on the national Red List, and small s ...[more]

PMID: 25238059

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Project description:Reynoutria japonica is one of the most harmful invasive species in the world, dramatically reducing the diversity of resident vegetation. To mitigate the impact of R. japonica on ecosystems and properly manage affected areas, understanding the mechanisms behind this plant's invasive success is imperative. This study aimed to comprehensively analyse plant communities invaded by R. japonica, taking into account species traits, habitat conditions and seasonal variability, and to determine the ecological profile of species that withstand the invader's pressure. The study was performed in fallow and riparian areas in southern Poland. Pairs of adjacent plots were established at 25 sites with no obvious signs of recent human disturbance. One plot contained R. japonica, and the other contained only resident vegetation. For each plot, botanical data were collected and soil physicochemical properties were determined. Twelve sites were surveyed four times, in two springs and two summers, to capture seasonal variability. The presence of R. japonica was strongly associated with reduced resident plant species diversity and/or abundance. In addition to the ability to quickly grow and form a dense canopy that shades the ground, the success of the invader likely resulted from the production of large amounts of hard-to-decompose litter. The indirect impact of R. japonica by controlling the availability of nutrients in the soil might also play a role. A few species coexisted with R. japonica. They can be classified into three groups: (i) spring ephemerals - geophytic forbs with a mixed life history strategy, (ii) lianas with a competitive strategy and (iii) hemicryptophytic forbs with a competitive strategy. Species from the first two groups likely avoided competition for light by temporal or spatial niche separation (they grew earlier than or above the invasive plant), whereas the high competitive abilities of species from the third group likely enabled them to survive in R. japonica patches.

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Dataset Information

Invasiveness does not predict impact: response of native land snail communities to plant invasions in riparian habitats.

Publications

Invasiveness does not predict impact: response of native land snail communities to plant invasions in riparian habitats.

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