The presence of native grasses in communities can suppress native forbs through competition and indirectly benefit these forbs by suppressing the invasion of highly competitive exotic species. We conducted a greenhouse experiment to examine the potential of direct and indirect interactions to influence the aboveground biomass of four native forb species in the presence of the native perennial grass Schizachyrium scoparium and exotic invasive Lespedeza cuneata. We examined patterns of growth for the invasive legume, the perennial grass, and four native species in four scenarios: 1) native species grown with the grass, 2) native species grown with the legume, 3) native species grown with both the grass and legume together, and 4) native species grown alone. Schizachyrium scoparium significantly decreased biomass of all forb species (p<0.05). In contrast, L. cuneata alone only significantly affected biomass of Asclepias tuberosa; L. cuneata increased the biomass of A. tuberosa only when the grass was present. When S. scoparium and L. cuneata were grown together, L. cuneata had significantly lower biomass (p = 0.007) and S. scoparium had significantly greater biomass (p = 0.002) than when each grew alone. These reciprocal effects suggest a potential pathway by which L. cuneata could alter forb diversity in grassland communities In this scenario, L. cuneata facilitates grass growth and competition with other natives. Our results emphasize the importance of monitoring interactions between exotic invasive plant species and dominant native species in grassland communities to understand pathways of plant community change.
<p>This poster summarises a range of new findings on monitoring and modelling the effectiveness of Natural Flood Management including from NERC/UKRI NFM programme over the last five years covering a range of nature based solutions designed to slow, store and infiltrate flood water. The updates cover the following areas: Quantitative evidence (monitoring and modelling) of effectiveness of different NFM features or systems of features; Performance failure of NFM measures or systems of measures; Evidence for climate change resilience of measures;&#160; Trade-offs between clusters of NFM features versus large individual NFM features; Evidence for resilience of NFM at high and low flows and; Evidence for integrated benefits including water resources and water quality in combination with flood risk regulation; Advances in distributed modelling of different NFM features and evidence for shifts in effective parameter shifts; Scaling modelled parameter shifts to represent changes at larger scales.</p>
<p>The poster also solicits additional quantitative evidence from international colleagues and will be used to update evidence summaries being used in the UK.</p>
Species‐specific herbivores are hypothesized to maintain plant diversity by preventing the dominance of any one plant species. However, a large proportion of herbivores have wide host ranges, and these generalists could have similar effects on plant community composition if they exhibit differences in their host preference. Here, we coupled laboratory and field experiments to test whether a common forest‐understorey snail (Neohelix alleni), a generalist herbivore, has the potential to influence forest composition through differential preference of their plant hosts.
We first performed a cafeteria‐style experiment to test whether N. alleni showed feeding preferences among leaves of five tree species and one shrub common to temperate forests in Missouri, USA. We then conducted a factorial snail and deer exclusion experiment to decouple the effects of snail herbivory from those of white‐tailed deer on seedling establishment of 1‐month‐old newly germinated seedlings of these six woody species in the field. Finally, we examined whether variation in both snail feeding preference and experimentally measured effects of snails on seedling establishment across plant species were related to their relative abundance measured in a 12‐ha forest plot.
In the laboratory, we found that snails preferred leaves of woody species that were less abundant in the forests relative to those species that were more common. In the forest, we found that experimental exclusion of snails had a stronger positive effect on seedling above‐ground biomass and survival over a 1‐year period than did exclusion of deer. Plant species found to be more preferred in the laboratory were also those that had lower seedling establishment in the forest due to the negative effects of snails.
Synthesis. Collectively, our results suggest that greater susceptibility to snail herbivory limits seedling establishment, perhaps contributing to differences in tree species relative abundance. Although less appreciated than their insect and mammal counterparts, herbivory by snails may be significant drivers to the assembly of forest tree communities.
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