Biotic resistance to plant invasion in grassland: Does seed predation increase with resident plant diversity?

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• 作者：Juliane Preukschas^a ; ^b ; ^{julianepreukschas@gmail.com" class="auth_mail} ; Michaela Zeiter^a ; ^b ; Markus Fischer^b ; ^c ; Andreas Stampfli^a ; ^b
• 关键词：Biotic filter ; Community invasibility ; Native non-native comparison ; Propagule pressure ; Seed availability ; Seed provenance ; Seed removal ; Seed size ; Semi-natural grassland ; Species richness
• 刊名：Basic and Applied Ecology
• 出版年：March, 2014
• 年：2014
• 卷：15
• 期：2
• 页码：133-141
• 全文大小：440 K

文摘

Seed predation impacts heavily on plant populations and community composition in grasslands. In particular, generalist seed predators may contribute to biotic resistance, i.e. the ability of resident species in a community to reduce the success of non-indigenous plant invaders. However, little is known of predators鈥?preferences for seeds of indigenous or non-indigenous plant species or how seed predation varies across communities. We hypothesize that seed predation does not differ between indigenous and non-indigenous plant species and that seed predation is positively related to plant species diversity in the resident community. The seed removal of 36 indigenous and non-indigenous grassland species in seven extensively or intensively managed hay meadows across Switzerland covering a species-richness gradient of 18-50 plant species per unit area (c. 2 m²) was studied. In mid-summer 2011, c. 24,000 seeds were exposed to predators in Petri dishes filled with sterilized soil, and the proportions of seeds removed were determined after three days鈥?exposure. These proportions varied among species (9.2-62.5%) and hay meadows (17.8-48.6%). Seed removal was not related to seed size. Moreover, it did not differ between indigenous and non-indigenous species, suggesting that mainly generalist seed predators were active. However, seed predation was positively related to plant species richness across a gradient in the range of 18-38 species per unit area, representing common hay meadows in Switzerland. Our results suggest that generalist post-dispersal seed predation contributes to biotic resistance and may act as a filter to plant invasion by reducing the propagule pressure of non-local plant species.