Preserving mobile insects in semi-natural grasslands : Minding the matrix
Weber, Julia LU
(2026)
- Abstract
- Declines of insect pollinator diversity in farmlands have neither been halted nor reversed despite large efforts to change the negative trend. One driver of this is agricultural intensification, which has resulted in landscape simplification by loss of non-crop habitats, and increased use of inorganic fertilizers and synthetic pesticides. Consequently, the presence of grazing animals in agricultural landscapes have decreased, leading to loss of semi-natural grasslands which are of great value for pollinating insects. Remaining grasslands may be under heavy grazing pressure, resulting in a rapid seasonal depletion of floral resources. Given that increasing the quality and quantity of grasslands is often costly and slow to yield results,... (More)
- Declines of insect pollinator diversity in farmlands have neither been halted nor reversed despite large efforts to change the negative trend. One driver of this is agricultural intensification, which has resulted in landscape simplification by loss of non-crop habitats, and increased use of inorganic fertilizers and synthetic pesticides. Consequently, the presence of grazing animals in agricultural landscapes have decreased, leading to loss of semi-natural grasslands which are of great value for pollinating insects. Remaining grasslands may be under heavy grazing pressure, resulting in a rapid seasonal depletion of floral resources. Given that increasing the quality and quantity of grasslands is often costly and slow to yield results, there is a growing need to expand conservation efforts beyond grasslands to include the surrounding agricultural landscape – the matrix – to gain a more effective conservation strategy for grassland pollinators. The matrix can provide complementary or supplementary floral resources for pollinating insects through for example mass-flowering crops. However, they often fail to sustain pollinators throughout the season, leading to hunger gaps during critical life stages. Leys, which are perennial grasslands grown for fodder production and increased soil quality, often include legumes which could offer floral resources for grassland pollinators. However, flower availability in leys may be depleted due to frequent harvesting or intensive grazing. This thesis aims to investigate if flower-rich leys in the matrix is an efficient measure of improving the conservation value of grasslands for pollinators. Using field data and satellite-based predictive modelling to map legume availability across landscapes, I investigate how resources from leys support bumblebee and butterfly populations in grasslands and in smaller habitats in the matrix, and experimentally test how mowing regimes affect bumblebee populations. From the four chapters of this thesis, three main findings can be highlighted: i) while legume-rich conventional leys provide floral resources despite being regularly mowed and grazed, organic leys provide a more consistent flower resource, ii) variation in the extent of flower-rich leys and the area of semi-natural grasslands in the surrounding landscape, when combined with measures increasing the value of smaller habitats such as field borders, influence species richness and abundance of both bumblebees and butterflies in agricultural landscapes, and iii) legume flower cover in leys can be reliably predicted from remotely sensed phenology and productivity data combined with management and soil variables. The results and conclusions of this thesis fill a knowledge gap of which holds potential in increasing the conservation value of grasslands for farmland pollinator populations. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/acac88d1-d3f3-40ad-84cd-4551fd217c6d
- author
- Weber, Julia
LU
- supervisor
-
- Henrik Smith LU
- Johan Ekroos LU
- Anna Persson LU
- Ola Olsson LU
- opponent
-
- Professor van Dyck, Hans, University Louvain-la-Neuve
- organization
- alternative title
- Bevarandet av mobila insekter i naturbetesmarker : Vikten av det omkringliggande jordbrukslandskapet
- publishing date
- 2026-04-28
- type
- Thesis
- publication status
- published
- subject
- keywords
- landscape complementation, farmland biodiversity, conservation, leys, bumblebees, butterflies, legumes, clover, semi-natural grasslands, remote sensing, machine learning, PPI
- pages
- 57 pages
- publisher
- Lund University
- defense location
- Blue Hall, Ecology building
- defense date
- 2026-05-22 13:00:00
- ISBN
- 978-91-8104-918-3
- 978-91-8104-917-6
- project
- Preserving mobile insects in semi-natural grasslands – Minding the matrix
- language
- English
- LU publication?
- yes
- id
- acac88d1-d3f3-40ad-84cd-4551fd217c6d
- date added to LUP
- 2026-04-28 16:18:33
- date last changed
- 2026-04-29 11:36:53
@phdthesis{acac88d1-d3f3-40ad-84cd-4551fd217c6d,
abstract = {{Declines of insect pollinator diversity in farmlands have neither been halted nor reversed despite large efforts to change the negative trend. One driver of this is agricultural intensification, which has resulted in landscape simplification by loss of non-crop habitats, and increased use of inorganic fertilizers and synthetic pesticides. Consequently, the presence of grazing animals in agricultural landscapes have decreased, leading to loss of semi-natural grasslands which are of great value for pollinating insects. Remaining grasslands may be under heavy grazing pressure, resulting in a rapid seasonal depletion of floral resources. Given that increasing the quality and quantity of grasslands is often costly and slow to yield results, there is a growing need to expand conservation efforts beyond grasslands to include the surrounding agricultural landscape – the matrix – to gain a more effective conservation strategy for grassland pollinators. The matrix can provide complementary or supplementary floral resources for pollinating insects through for example mass-flowering crops. However, they often fail to sustain pollinators throughout the season, leading to hunger gaps during critical life stages. Leys, which are perennial grasslands grown for fodder production and increased soil quality, often include legumes which could offer floral resources for grassland pollinators. However, flower availability in leys may be depleted due to frequent harvesting or intensive grazing. This thesis aims to investigate if flower-rich leys in the matrix is an efficient measure of improving the conservation value of grasslands for pollinators. Using field data and satellite-based predictive modelling to map legume availability across landscapes, I investigate how resources from leys support bumblebee and butterfly populations in grasslands and in smaller habitats in the matrix, and experimentally test how mowing regimes affect bumblebee populations. From the four chapters of this thesis, three main findings can be highlighted: i) while legume-rich conventional leys provide floral resources despite being regularly mowed and grazed, organic leys provide a more consistent flower resource, ii) variation in the extent of flower-rich leys and the area of semi-natural grasslands in the surrounding landscape, when combined with measures increasing the value of smaller habitats such as field borders, influence species richness and abundance of both bumblebees and butterflies in agricultural landscapes, and iii) legume flower cover in leys can be reliably predicted from remotely sensed phenology and productivity data combined with management and soil variables. The results and conclusions of this thesis fill a knowledge gap of which holds potential in increasing the conservation value of grasslands for farmland pollinator populations.}},
author = {{Weber, Julia}},
isbn = {{978-91-8104-918-3}},
keywords = {{landscape complementation; farmland biodiversity; conservation; leys; bumblebees; butterflies; legumes; clover; semi-natural grasslands; remote sensing; machine learning; PPI}},
language = {{eng}},
month = {{04}},
publisher = {{Lund University}},
school = {{Lund University}},
title = {{Preserving mobile insects in semi-natural grasslands : Minding the matrix}},
url = {{https://lup.lub.lu.se/search/files/248686053/Thesis_Julia_Weber_electronic.pdf}},
year = {{2026}},
}