Alexandra Klein

Alexandra Klein
University of Freiburg | Albert-Ludwigs-Universität Freiburg · Chair of Nature Conservation and Landscape Ecology

Professor

About

538
Publications
231,725
Reads
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37,659
Citations
Citations since 2017
200 Research Items
24160 Citations
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Introduction
Alexandra-Maria Klein is the chair for Nature Conservation and Landscape Ecology at the University of Freiburg in Germany. Her main research focuses on biodiversity and ecosystem functions mediated by macro-organisms e.g. pollination, herbivory, seed dispersal, seed predation and parasitism of insects and started with research on the importance of insect pollination for coffee in Indonesia in 1998. She aims to understand the effects of global environmental changes and uncertainties on the relationship between biodiversity and ecosystem functions.

Publications

Publications (538)
Article
1. The diversity in meadows is affected by numerous aspects, such as the amount and type of fertilisation and the timing and frequency of cutting. The effects of mowing on the diversity of plants and insects have been studied in detail. However, the effect of mulching (vegetation is cut, shredded, and left in place, instead of being removed) on ins...
Preprint
Under the terms of the PoshBee agreement, the members tasked with delivering Work Package 7 carried out semi-field and field studies on honey bees, bumble bees and solitary bees. These studies involved the exposure of the bees to more than one stressor, for example a fungicide and an insecticide or a fungicide and a nutritional deficiency. This is...
Article
Full-text available
Retention forestry promotes certain forest structural elements to enhance biodiversity. It is unclear however to what extent retention measures are suited to enhance the biodiversity of bees and wasps, and how relationships to structural elements promoted by retention may differ when habitat-based classifications are accounted for. Here, we analyze...
Article
Forests in Germany are occupied with roads, paths, and trails with a density of 5.03 km/km². Their construction and maintenance create a network of verges promoting flowering plants. Whether these verges are visited by bees, which factors are determining their abundance, diversity, and composition, and which flowering resources are used is unknown....
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Full-text available
Addressing global biodiversity loss requires an expanded focus on multiple dimensions of biodiversity. While most studies have focused on the consequences of plant interspecific diversity, our mechanistic understanding of how genetic diversity within plant species affects plant productivity remains limited. Here, we use a tree species × genetic div...
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Full-text available
Mulching, cutting of the vegetation without plant biomass removal, is a common alternative to mowing. The aim of our study was to find out if the mulching of forest meadows at different time points affects cavity-nesting bees and wasps. We exposed trap nests for cavity-nesting bees and wasps at 24 forest meadows in south-western Germany over 2 year...
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Recent studies have emphasized forests as crucial habitat for wild bees. In Europe, most forests are managed following the principles of close-to-nature silviculture, which combine timber production and nature conservation. However , open late and early successional stages within these forests are largely missing, which could be important for wild...
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Pesticide exposure and food stress are major threats to bees, but their potential synergistic impacts under field-realistic conditions remain poorly understood and are not considered in current pesticide risk assessments. We conducted a semi-field experiment to examine the single and interactive effects of the novel insecticide flupyradifurone (FPF...
Article
1. Wild bees importantly pollinate both crop and wild plants. Yet, in intensive agricultural landscapes, wild bees are rare due to resource limitations of nectar and pollen. Flower strips and hedges are often used as resource enhancements for wild bees to overcome this shortage, but provide floral resources only during specific time periods. To sus...
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Full-text available
To provide a complete portrayal of the multiple factors negatively impacting insects in agricultural landscapes it is necessary to assess the concurrent incidence, magnitude, and interactions among multiple stressors over substantial biogeographical scales. Trans-national ecological field investigations with wide-ranging stakeholders typically enco...
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During the main COVID-19 global pandemic lockdown period of 2020 an impromptu set of pollination ecologists came together via social media and personal contacts to carry out standardised surveys of the flower visits and plants in gardens. The surveys involved 67 rural, suburban and urban gardens, of various sizes, ranging from 61.18° North in Norwa...
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Background Retention forestry is a management strategy aiming to mitigate biodiversity loss by retaining structural elements such as dead trees that would otherwise be removed. Here we analyze the biomass, diversity and abundance among forest beetles collected using window traps on 128 1-ha forest sites reflecting gradients in the amount of structu...
Preprint
Flower-visiting insects in agroecosystems forage on field-edge weeds often exposed to agrochemicals that may compromise the quality of their floral resources. We conducted complementary field and greenhouse experiments to evaluate the: 1) effect of low concentrations of agrochemical exposure on nectar and pollen quality and 2) relationship between...
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Wild bee populations are declining due to human activities, such as land use, which strongly affect the composition and diversity of available plants and food sources. The chemical composition of food (i.e. nutrition), in turn, determines health, resilience and fitness of bees. However, for pollinators, the term health is recent and subject to deba...
Article
Most forests in Europe are managed but differ in their management intensity. This has different implications for structural- and environmental conditions and subsequently for the conservation of ecological communities, their interactions and functional consequences. Differences in silvicultural treatments, especially those promoting rare habitat st...
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Pesticide exposure is considered a major driver of pollinator decline and the use of neonicotinoid insecticides has been restricted by regulatory authorities due to their risks for pollinators. Impacts of new alternative sulfoxamine-based compounds on solitary bees and their potential interactive effects with other commonly applied pesticides in ag...
Preprint
Full-text available
Addressing global biodiversity loss requires an expanded focus on multiple dimensions of biodiversity. While most studies have focused on the consequences of plant interspecific diversity, our mechanistic understanding of how the diversity within a given plant species (genetic diversity) affects plant productivity remains limited. Here, we use a tr...
Article
Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop y...
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Full-text available
Bees are exposed to various stressors, including pesticides and lack of flowering resources. Despite potential interactions between these stressors, the impacts of pesticides on bees are generally assumed to be consistent across bee-attractive crops, and regulatory risk assessments of pesticides neglect interactions with flowering resources. Furthe...
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In intensive agricultural landscapes semi-natural habitats for pollinators are often limited, although willingness to establish pollinator habitat is increasing among farmers. A common pollinator enhancement measure is to provide flower strips, but existent or improved hedgerows might be more effective. In this study, we compare the effectiveness o...
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The quality of wintering habitats, such as depth of snow cover, plays a key role in sustaining population dynamics of Arctic lemmings. However, few studies so far investigated habitat use during the Arctic winter. Here, we used a unique long-term time series to test whether lemmings are associated with topographical and vegetational habitat feature...
Article
Animal pollinators are globally threatened by anthropogenic land use change and agricultural intensification. The yield of many food crops is therefore negatively impacted because they benefit from biotic pollination. This is especially the case in the tropics. For instance, fruit set of Coffea arabica has been shown to increase by 10–30% in planta...
Article
Habitat disturbance can have negative impacts on biodiversity, such as reducing species richness. The effects of habitat disturbances on parasite infections of host species, potentially altering their survival rate and thus abundance, are less well known. We examined the influence of forest logging in combination with seasonality, host abundance, h...
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Sulfoximines, the next generation systemic insecticides developed to replace neonicotinoids, have been shown to negatively impact pollinator development and reproduction. However, field-realistic studies on sulfoximines are few and consequences on pollination services unexplored. Moreover, the impacts of other agrochemicals such as fungicides, and...
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• Floral nectar is considered the most important floral reward for attracting pollinators. It contains large amounts of carbohydrates besides variable concentrations of amino acids and thus represents an important food source for many pollinators. Its nutrient content and composition can, however, strongly vary within and between plant species. The...
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Functional traits mediate the response of communities to disturbances (response traits) and their contribution to ecosystem functions (effect traits). To predict how anthropogenic disturbances influence ecosystem services requires a dual approach including both trait concepts. Here, we use a response‐effect trait conceptual framework to understand...
Article
Flower strips are a frequently adopted measure to conserve insects, especially pollinators, and are subsidized as Agri-Environmental Scheme in many regions. They provide a high quantity of flowers, but their flower species composition and phenological development is mostly uniform. This may result in only a fraction of pollinator species being enha...
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From regional to global scales, anthropogenic environmental change is causing biodiversity loss and reducing ecosystem functionality. Previous studies have investigated the relationship between plant diversity and functional insect communities in temperate and also in tropical grasslands and forests. However, few studies have explored these dynamic...
Article
Reversing the decline of biodiver-sity in European agricultural land-scapes is urgent. We suggest eightmeasures addressing politics, eco-nomics, and civil society to instigatetransformative changes in agricul-tural landscapes. We emphasizethe need for a well-informed societyand political measures promotingsustainable farming by combiningfood produc...
Article
The importance of wild bees for crop pollination is well established, but less is known about which species contribute to service delivery to inform agricultural management, monitoring and conservation. Using sites in Great Britain as a case study, we use a novel qualitative approach combining ecological information and field survey data to establi...
Preprint
Full-text available
PoshBee is a 5-year funded project (2018-2023) that aims to support healthy bee populations, sustainable beekeeping, and consequently pollination for crops and wildflowers across Europe. To do this we take a range of approaches, from the laboratory to the field, from molecules to ecosystems, and from fundamental science to risk assessment. This doc...
Article
Structural complexity enhancement (SCE) is a forest restoration approach aiming to maintain or increase biodiversity in managed, secondary forests. Whether the diversity of wild bees also benefits from such restoration measures in temperate forests is not well studied. We conducted a restoration experiment in secondary spruce forests on twelve 50 ×...
Data
Single page summary of Vanderplank et al (2021) - contains a QR code for accessing the paper
Data
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Article
Full-text available
Current global change substantially threatens pollinators, which directly impacts the pollination services underpinning the stability, structure and functioning of ecosystems. Among these threats, many synergistic drivers such as habitat destruction and fragmentation, increasing use of agrochemicals, decreasing resource diversity as well as climate...
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Full-text available
Plant diversity affects multi-trophic communities, but in young regrowth forests, where forest insects are in the process of re-establishment, other biotic and also abiotic factors might be more important. We studied cavity-nesting bees, wasps and their natural enemies along an experimental tree diversity gradient in subtropical South-East China. W...
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While an increasing number of studies indicate that the range, diversity and abundance of many wild pollinators has declined, the global area of pollinator-dependent crops has significantly increased over the last few decades. Crop pollination studies to date have mainly focused on either identifying different guilds pollinating various crops, or o...
Article
While an increasing number of studies indicate that the range, diversity and abundance of many wild pollinators has declined, the global area of pollinator-dependent crops has significantly increased over the last few decades. Crop pollination studies to date have mainly focused on either identifying different guilds pollinating various crops, or o...
Article
Full-text available
Exposure to pesticides is considered a major threat to bees and several neonicotinoid insecticides were recently banned in cropland within the European Union in light of evidence of their potential detrimental effects. Nonetheless, bees remain exposed to many pesticides whose effects are poorly understood. Recent evidence suggests that one of the m...
Article
Full-text available
From regional to global scales, anthropogenic environmental change is causing biodiversity loss and reducing ecosystem functionality. Previous studies have investigated the relationship between plant diversity and functional insect communities in temperate and also in tropical grasslands and forests. However, few studies have explored these dynamic...
Article
Plant and pollinator diversity have declined concurrently in Europe in the last half century. We studied plant–bumblebee food webs to understand the effects of two agri-environmental schemes (AES, organic farming and environmentally-friendly management practice) vs. conventional farming as control group, landscape structure (heterogeneous vs. homog...
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1. Plant diversity begets diversity at other trophic levels. While species richness is the most commonly used measure for plant diversity, the number of evolutionary lineages (i.e. phylogenetic diversity) could theoretically have a stronger influence on the community structure of co-occurring organisms. However, this prediction has only rarely been...
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Full-text available
Logging and mining are widespread in most West African countries and considering their socio-economic importance, little is known about their ecological impacts. In this study, we investigated the effects of chainsaw milling (logging) and artisanal mining on terrestrial small mammal communities in a tropical forest in Ghana. For this, we compared a...
Preprint
Collapsing lemming cycles have been observed across the Arctic, presumably due to global warming creating less favorable winter conditions. The quality of wintering habitats, such as depth of snow cover, plays a key role in sustaining population dynamics of arctic lemmings. However, few studies so far investigated habitat use during the arctic wint...
Article
PoshBee is a 5-year funded project (2018-2023) that aims to support healthy bee populations, sustainable beekeeping, and consequently pollination for crops and wildflowers across Europe. To do this we take a range of approaches, from the laboratory to the field, from molecules to ecosystems, and from fundamental science to risk assessment. This doc...
Preprint
Full-text available
The European Union’s (EU) Common Agricultural Policy (CAP) still fails to address the environmental and socioeconomic challenges of EU’s agriculture. Agricultural ecosystems are further degrading, biodiversity is declining and agricultural Greenhouse Gas (GHG) emissions remain high. At the same time, farms are facing unresolved socio-economic chall...
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Urban green spaces such as gardens often consist of native and exotic plant species, which provide pollen and nectar for flower-visiting insects. Although some exotic plants are readily visited by pollinators, it is unknown if and at which time of the season exotic garden plants may supplement or substitute for flower resources provided by native p...
Article
Retention forestry intends to promote biodiversity by retaining deadwood and tree-related microhabitats. Simultaneously, production forests undergo major structural changes by conversion into near-natural forests. As insect biomass is declining, it is important to understand how insect communities respond to management-related changes in forest str...
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Full-text available
Abstract Hairiness is a salient trait of insect pollinators that has been linked to thermoregulation, pollen uptake and transportation, and pollination success. Despite its potential importance in pollination ecology, hairiness is rarely included in pollinator trait analyses. This is likely due to the lack of standardized and efficient methods to m...
Book
Full-text available
Farmers, gardeners and agronomists have detailed knowledge on how to maximise high quality crop production, especially in the context of external inputs including fertilization and pest management. However, detailed information on pollination is mainly available in the international scientific literature and often not accessible for local farmers o...
Book
Full-text available
Fazendeiros, agricultores e agrônomos têm conhecimentos detalhados de como maximizar a produção e qualidade de seus cultivos agrícolas, especialmente no contexto de insumos externos como os fertilizantes e o manejo de pragas. Contudo, informações sobre polinização geralmente estão disponíveis apenas na literatura científica internacional e quase s...
Article
Full-text available
Biological corridors are an important conservation strategy to increase connectivity between populations—mainly vertebrates—in fragmented landscapes, which often require habitat restoration to achieve physical connections. Non-target groups such as bees could benefit from corridors while contributing to the restoration process given their role as p...
Article
Full-text available
Nectar is crucial to maintain plant-pollinator mutualism. Nectar quality (nutritional composition) can vary strongly between individuals of the same plant species. The factors driving such inter-individual variation have however not been investigated closer. We investigated nectar quality of field scabious, Knautia arvensis in different grassland p...
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Retention forestry, which retains a portion of the original stand at the time of harvesting to maintain continuity of structural and compositional diversity, has been originally developed to mitigate the impacts of clear‐cutting. Retention of habitat trees and deadwood has since become common practice also in continuous‐cover forests of Central Eur...
Chapter
Verschwände die Vielfalt der Insekten, ginge uns Existenzielles verloren. Die Natur und unsere Ernährung würden sich ändern, doch Bestäubungsroboter könnten diesen Verlust nicht kompensieren.
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Insect populations decline, particularly in intensively managed agricultural landscapes. Insect communities are influenced by current agricultural practices, which are themselves determined by the economic, political and social frameworks. We highlight these direct and indirect drivers affecting insect communities, raise key research questions and...
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In urban areas, the diversity and abundance of cavity-nesting Hymenoptera may be restricted due to scarce nesting resources. Artificial nesting sites (nesting aids) are being installed to compensate for this shortage in a growing number of private gardens and public greenspaces to support Hymenoptera (especially bee) diversity. Various nesting aids...
Article
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1. Ecologists have long suspected that species are more likely to interact if their traits match in a particular way. For example, a pollination interaction may be more likely if the proportions of a bee's tongue fit a plant's flower shape. Empirical estimates of the importance of trait-matching for determining species interactions, however, vary s...
Article
Full-text available
Pollination by insects is a key input into many crops, with managed honeybees often being hired to support pollination services. Despite substantial research into pollination management, no European studies have yet explored how and why farmers managed pollination services and few have explored why beekeepers use certain crops. Using paired surveys...