eLTER PLUS Deliverable D9.1 - eLTER network representativeness towards biodiversity pressures and trends
Creators: name: Musche, Martin
name: Milanovic, Marija
name: Kühn, Ingolf
Publisher: name: Zenodo
Year: 2025
Subjects: subject: Biodiversity
subject: Vegetation
subject: time series
subject: Plants
subject: Forest
subject: eLTER PLUS

description: Global biodiversity has changed tremendously over the past 50 years due to the impact of anthropogenic drivers such as land use change, direct exploitation, pollution, climate change and invasive species. The eLTER network's biodiversity surveys provide a unique opportunity to investigate these changes and to assess their impacts. The present report has two main objectives. First, it will investigate whether eLTER data are suitable for analysing long-term biodiversity change at the European scale and whether these changes can be linked to potential drivers. The second aim is to evaluate eLTER workflows and services that benefit the scientific community and to provide recommendations for the further development of the eLTER Research Infrastructure. To address the first objective, we conducted a case study in which we analysed changes in the species composition of plant communities at eLTER sites. The experiences gained from this work were used to address the second objective.

Changes in species composition within local communities are among the most pronounced components of biodiversity change. Colonisations, extinctions and shifts in abundances can lead to a homogenisation or heterogenisation of communities. By using eLTER vegetation time series covering the period from 1995 to 2018 we investigated the relative importance of these processes by applying two different approaches. First, we partitioned temporal changes in spatial β-diversity into colonisation and extinction events and explored to what extent both processes have contributed to the homogenization or heterogenisation of local plant communities. Second, we analysed temporal β-diversity to identify sites that have extraordinarily changed.

Spatial differentiation among plant communities increased over time. This change was influenced more by extinctions than by colonisations. Extinctions resulting in a heterogenisation of plant communities is an indication of a stronger reduction of widespread species as compared to rare species. The analysis of temporal β-diversity likewise showed that extinctions had a more pronounced effect on community composition than colonisations. Further analysis indicated that species losses and gains over time may be related to changing precipitation patterns at eLTER sites.

The case study showed that eLTER biodiversity data are principally well suited to answer questions concerning biodiversity change at the continental scale. However, the study also points at limitations resulting from restricted spatial representativity, low sampling frequencies and various types of heterogeneity in the data. Recommendations are made to increase representativeness and to specify existing eLTER Standard Observations. Further considerations concern the development of IT services, with a focus on the documentation of metadata, data acquisition, quality control, harmonisation of variables and networking with other initiatives.