Abstract
The rapid pace of human development has put great pressure on the natural world. The impact of global change drivers such as land-use change, climate change, pollution, and over-harvesting is so great that scientists have declared a new geological epoch, the ‘Anthropocene’. Current research shows that biodiversity is declining globally; however, reaching a consensus on how biodiversity is changing at the local scale and the role of global change drivers can be difficult. Key challenges include biases and gaps in our knowledge, a scarcity of temporal analyses, and an anthropocentric approach to measuring
the environment. Biodiversity is also a multifaceted concept; the number of species at a site, their total abundance, or the distribution of their traits, may each respond uniquely to human disturbance. This thesis attempts to identify and address some of the knowledge gaps regarding humanity’s impact on biodiversity. I use complementary research approaches to achieve this goal, resulting in a literature review and two analytical papers.
In the first chapter I review the overall state of the biodiversity literature dealing with landuse change – the leading cause of declines in nature. The results indicate that the current literature is heavily biased towards vertebrates and towards North America and Europe.
Therefore, we may be overlooking important differences in the sensitivity of different species groups or in regional land-use pressures. Geographic biases also limited the range of climates and land use histories that were covered – both of which may modify the effect of land-use change. In the second chapter I examine the species-environment relationship by combining extensive citizen science data on bird observations across Denmark with remotely sensed three-dimensional vegetation structure. Vertical complexity proved to be an important determinant of richness patterns across different ecological guilds, although traditional land cover maps helped explain community composition. The results illustrate how three-dimensional structure can improve biodiversity predictions by capturing proximate habitat features within coarse land-cover classes.
While the second chapter considers spatial comparisons, the third focusses on temporal trends by addressing how local biodiversity is changing through time. For this I use volunteer bird observations spanning more than four decades of change in Denmark (1976-2020). Bird communities showed sharp declines in abundance and accelerated, directional change in community composition. However, these changes could not be explained by trends of local climate or land-cover change, highlighting the complex relationship between local biodiversity change and the role of anthropogenic drivers. In conclusion, studying the impact of multiple global change drivers on multiple dimensions of biodiversity –across both time and space– is a challenging endeavour, but it is imperative for the preservation of nature and its contributions to our survival and wellbeing. I hope that this thesis adds insight into the debates surrounding this topic.
the environment. Biodiversity is also a multifaceted concept; the number of species at a site, their total abundance, or the distribution of their traits, may each respond uniquely to human disturbance. This thesis attempts to identify and address some of the knowledge gaps regarding humanity’s impact on biodiversity. I use complementary research approaches to achieve this goal, resulting in a literature review and two analytical papers.
In the first chapter I review the overall state of the biodiversity literature dealing with landuse change – the leading cause of declines in nature. The results indicate that the current literature is heavily biased towards vertebrates and towards North America and Europe.
Therefore, we may be overlooking important differences in the sensitivity of different species groups or in regional land-use pressures. Geographic biases also limited the range of climates and land use histories that were covered – both of which may modify the effect of land-use change. In the second chapter I examine the species-environment relationship by combining extensive citizen science data on bird observations across Denmark with remotely sensed three-dimensional vegetation structure. Vertical complexity proved to be an important determinant of richness patterns across different ecological guilds, although traditional land cover maps helped explain community composition. The results illustrate how three-dimensional structure can improve biodiversity predictions by capturing proximate habitat features within coarse land-cover classes.
While the second chapter considers spatial comparisons, the third focusses on temporal trends by addressing how local biodiversity is changing through time. For this I use volunteer bird observations spanning more than four decades of change in Denmark (1976-2020). Bird communities showed sharp declines in abundance and accelerated, directional change in community composition. However, these changes could not be explained by trends of local climate or land-cover change, highlighting the complex relationship between local biodiversity change and the role of anthropogenic drivers. In conclusion, studying the impact of multiple global change drivers on multiple dimensions of biodiversity –across both time and space– is a challenging endeavour, but it is imperative for the preservation of nature and its contributions to our survival and wellbeing. I hope that this thesis adds insight into the debates surrounding this topic.
Originalsprog | Engelsk |
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Forlag | GLOBE Institute, Faculty of Health and Medical Sciences, University of Copenhagen |
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Antal sider | 142 |
Status | Udgivet - 2022 |