Widespread decline in Central European plant diversity across six decades

Abstract Based on plant occurrence data covering all parts of Germany, we investigated changes in the distribution of 2136 plant species between 1960 and 2017. We analyzed 29 million occurrence records over an area of ~350,000 km 2 on a 5 × 5 km grid using temporal and spatiotemporal models and accounting for sampling bias. Since the 1960s, more than 70% of investigated plant species showed declines in nationwide occurrence. Archaeophytes (species introduced before 1492) most strongly declined but also native plant species experienced severe declines. In contrast, neophytes (species introduced after 1492) increased in their nationwide occurrence but not homogeneously throughout the country. Our analysis suggests that the strongest declines in native species already happened in the 1960s–1980s, a time frame in which often few data exist. Increases in neophytic species were strongest in the 1990s and 2010s. Overall, the increase in neophytes did not compensate for the loss of other species, resulting in a decrease in mean grid cell species richness of −1.9% per decade. The decline in plant biodiversity is a widespread phenomenon occurring in different habitats and geographic regions. It is likely that this decline has major repercussions on ecosystem functioning and overall biodiversity, potentially with cascading effects across trophic levels. The approach used in this study is transferable to other large‐scale trend analyses using heterogeneous occurrence data

A checklist for using Beals’ index with incomplete floristic monitoring data : reply to Christensen et al. (2021): Problems in using Beals’ index to detect species trends in incomplete floristic monitoring data

Christensen et al. criticized the application of Beals’ index of sociological favourability to adjust for incomplete species lists when comparing repeated surveys. Their main argument was that using Beals’ conditional occurrence probabilities would systematically underestimate biodiversity change compared to using observed frequencies. Although this might be the case for rare species, as we explicitly stated in our original publication, we here use a worked-out example to show that this criticism is unjustified for species that are sufficiently represented in the reference data set. In our opinion, the misconception derives from ignoring one of the key requirements for applying Beal's index, which is the use of a sufficiently large reference data set to derive a reliable co occurrence matrix. We here show how the predicted probability for the occurrence of a species depends on the size of the reference data set and give recommendations on the premises for applying Beals’ approach for monitoring purposes

Potential supply and actual use of cultural ecosystem services in mountain protected areas and their surroundings

The potential supply of ecosystem services is often assessed using land cover data. Assessment of actual use of ecosystem services by beneficiaries remains less covered and is often assumed to be congruent with potential supply. However, we believe that to contribute to the sustainable management of multifunctional landscapes, more insights are needed on the links between landscape characteristics and the various facets of ecosystem services. In this paper, we assess cultural ecosystem services (CES) such as recreation, inspiration or scenic beauty in three European mountain protected areas and their surroundings. We study the alignment between the potential supply and actual use of CES. CES potential supply was modelled using six biophysical indicators derived from earth observation and open geospatial data. For CES actual use, we employed participatory mapping with protected area visitors and local experts. We modelled CES actual use as a function of landscape biophysical indicators, weighted by (i) stated and (ii) revealed visitor preferences, and accessibility in each protected area using generalized additive mixed-effects models. Accessibility alone could explain around 50% of the variability of CES actual use, and with the additional inclusion of the ‘natural and cultural features’ variable, the actual use models reached an explanatory power of around 80% for all three case-studies. Importantly, biophysical information using land cover data alone cannot fully describe CES actual use, and there was little congruency between modelled potential supply and actual use. Additional socio-cultural features are required to explain the patterns of locations where protected area visitors enjoy CES. Our results can inform visitor management by addressing CES actual use and thereby provide evidence for landscape management and conservation planning and management, including offering a rewarding experience of nature for visitors

More losses than gains during one century of plant biodiversity change in Germany

Long-term analyses of biodiversity data highlight a 'biodiversity conservation paradox': biological communities show substantial species turnover over the past century, but changes in species richness are marginal. Most studies, however, have focused only on the incidence of species, and have not considered changes in local abundance. Here we asked whether analysing changes in the cover of plant species could reveal previously unrecognized patterns of biodiversity change and provide insights into the underlying mechanisms. We compiled and analysed a dataset of 7,738 permanent and semi-permanent vegetation plots from Germany that were surveyed between 2 and 54 times from 1927 to 2020, in total comprising 1,794 species of vascular plants. We found that decrements in cover, averaged across all species and plots, occurred more often than increments; that the number of species that decreased in cover was higher than the number of species that increased; and that decrements were more equally distributed among losers than were gains among winners. Null model simulations confirmed that these trends do not emerge by chance, but are the consequence of species-specific negative effects of environmental changes. In the long run, these trends might result in substantial losses of species at both local and regional scales. Summarizing the changes by decade shows that the inequality in the mean change in species cover of losers and winners diverged as early as the 1960s. We conclude that changes in species cover in communities represent an important but understudied dimension of biodiversity change that should more routinely be considered in time-series analyses