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Plant-insect interactions in grassland ecosystems : Assessing consequences of landscape change and environmental stressors

In English

Författare

Summary, in English

Plant-insect interactions are crucial for sustaining biodiversity and ecosystem functioning in grassland ecosystems. Mutualistic pollination and antagonistic herbivory drive ecological processes such as nutrient cycling, community assembly, and food web stability. However, anthropogenic pressures, including land-use change, agricultural intensification, and environmental stressors like drought and nutrient deposition, are disrupting these interactions, impacting ecosystem resilience and productivity. This thesis explores how landscape composition and local environmental factors influence plant-pollinator and plant-herbivore interactions across spatial scales, integrating field surveys and experimental approaches to uncover biodiversity patterns and ecosystem stability mechanisms in semi-natural grasslands. Field surveys across 18 semi-natural grasslands in southern Sweden reveal that landscape composition profoundly shapes herbivore communities and interaction networks. Arable fields increased beetle abundance but reduced leafhopper diversity, while forested areas and permanent grasslands enhanced species richness and stabilized interaction networks. Permanent grasslands promoted greater leaf and stem herbivory, whereas arable crop cover suppressed herbivory intensity. Despite changes in network structure, plant-herbivore networks exhibited resilience, driven by generalist herbivores buffering against specialist declines. Structural equation modeling highlighted indirect landscape effects on herbivory via shifts in plant community composition and functional traits, with taller plants and those with higher specific leaf area being disproportionately targeted. A mesocosm experiment complemented these findings, assessing the interactive effects of drought, nutrient availability, and herbivory on plant reproductive performance and pollinator visitation. Drought increased pollinator visitation, likely due to floral enhancement under water stress, while nutrient enrichment boosted flower production. However, herbivory reduced viable flowers, limiting the reproductive benefits of nutrient addition. Seed production was highly sensitive to drought-nutrient interactions, with drought suppressing seed pod formation under low nutrients but exerting negligible effects under high nutrient availability. This thesis underscores the intricate and context-dependent nature of plant-insect interactions, highlighting the joint roles of landscape composition and local stressors in shaping herbivory, pollination, and plant reproduction. By demonstrating the importance of preserving semi-natural grasslands and promoting habitat heterogeneity, this work offers valuable insights for mitigating the adverse effects of land-use change and ensuring the stability of plant-insect networks amidst global change.

Publiceringsår

2025-01-10

Språk

Engelska

Dokumenttyp

Doktorsavhandling

Förlag

Lund University

Ämne

  • Environmental Sciences related to Agriculture and Land-use
  • Ecology

Nyckelord

  • plant-insect interactions
  • semi-natural grasslands
  • landscape composition
  • herbivory
  • functional traits
  • herbivore-host plant interactions,
  • network analysis,
  • nutrient availability
  • drought stress,

Aktiv

Published

Handledare

ISBN/ISSN/Övrigt

  • ISBN: 978-91-8104-358-7
  • ISBN: 978-91-8104-359-4

Försvarsdatum

7 februari 2025

Försvarstid

09:00

Försvarsplats

Blå hallen, Ekologihuset

Opponent

  • Martin Gossner (Professor)