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 km2 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.

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Lines 376-378: I don't see the direct link between homogenization and equality of change among losers and winners. Either prove/show the link mathematically, or drop the statement.Probably, this disagreement is based on how we define homogeneity. In our opinion, homogenization is the direct consequence of redistribution of the species' cover. If decreases are distributed more equally (that is also more homogeneously) across many species and increases in cover are concentrated in few species, the latter (that is the winners) will be increasing in many communities. In consequence, the dissimilarity in species composition between these communities has to decrease (given that a quantitative dissimilarity measure is used). Mathematically, this would have to be shown by a decrease in dissimilarity, which however, is difficult to demonstrate across all plot records in our data set as many communities have no species in common. In our opinion, homogenization probably occurs within habitat types, but opening this discussion and carrying out the analysis would open a can of worms. Thus, we have decided to down-tune this statement to: "Homogenisation occurs because, across all time series, few species consistently increase in their cover, meaning that the same species are winning in many communities." (new l 372-374)Referee #3 (Remarks to the Author):As before, I commend the authors on their analyses and believe this paper makes a novel and important contribution by documenting long-term plant biodiversity changes in terms of cover that would have been missed by simply focusing on species richness, as most previous work has done. But while the authors have produced a strong revision of their paper, in my opinion several outstanding issues remain, and some important comments have only been partially addressed. I appreciate the new analyses that the authors have performed, and overall the analyses are appropriate and justified, and data are presented correctly, as far as I can judge. The framing of the study is also now more compelling, and I think the unique value of the dataset and insights arising from it are now harnessed more effectively. That said, I still have some concerns about the framing of the study, explained in my comments below. The Results section has also been improved, but remains difficult to read in places -again, I make specific suggestions below. Overall, while the length appears to have been reduced, the text still seems unnecessarily wordy in places (e.g. in the Results and figure captions).Thank you for this positive assessment.Another aspect I raised previously and has still not been resolved, in my opinion, is when results are considered to be ecologically relevant or not, and I think there could be greater transparency in the paper about this. This relates to the way the story is set-up, as mentioned in my previous review. Specifically, the authors note that due to the large sample sizes, changes in species richness can be statistically significant even if effect sizes are small, and therefore conc...

Aim:The loss of biodiversity has raised serious concerns about the entailing losses of ecosystem services. Here, we explore the potential of repeated habitat mapping data to identify floristic changes over time. Using one German federal state as a case study, we assessed floristic changes between the 1980s and 2010s. These habitat data have great potential for analysis because of their high spatial coverage while also posing methodological challenges such as incomplete observation data. We developed a modelling approach that accounts for incomplete observations and explored the ability to detect temporal trends. Location:The Federal State of Schleswig-Holstein (Germany) Methods: We compiled plant species lists from the earliest (1980s) and most recent (2010s) habitat mapping survey and aligned differing habitat definitions across mapping campaigns. A total of 5,503 mapped polygons, each with a list of species records, intersected the two surveys. We accounted for underrecorded species by assigning occurrence probabilities, based on species co-occurrence information across all surveys, using Beals' index and tested the robustness of this approach by simulation experiments. For those species with significant increases and decreases in occurrence probability, we linked these trends to the species' functional characteristics. Results:We found a systematic loss of species that are moderately threatened.Species that indicate low nitrogen supply and high soil moisture declined, suggesting a shift towards a more eutrophic and drier landscape. Importantly, assessing specific plant traits associated with losses, we also detected a decrease in species with reddish and blueish flowers and species providing nectar, pointing to a decrease of insect-pollinated taxa. Main conclusions:The identified changes raise concerns that plant biodiversity has fundamentally changed over the last three decades, with concomitant consequences for ecosystem services, especially pollination. Given the general lack of historical | 783 BRUELHEIDE Et aL.

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Recent studies report declines in biomass, abundance and diversity of terrestrial insect groups. While anthropogenic land use is one likely contributor to this decline, studies assessing land cover as a driver of insect dynamics are rare and mostly restricted in spatial scale and types of land cover. In this study, we used rooftop-mounted car nets in a citizen science project (‘InsectMobile’) to allow for large-scale geographic sampling of flying insects across Denmark and parts of Germany. Citizen scientists sampled insects along 278 10 km routes in urban, farmland and semi-natural (grassland, wetland and forest) landscapes in the summer of 2018. We assessed the importance of local to landscape-scale effects and land use intensity by relating insect biomass to land cover in buffers of 50, 250, 500 and 1000 m along the routes. We found a negative association of urban cover and a positive association of farmland on insect biomass at a landscape-scale (1000 m buffer) in both countries. In Denmark, we also found positive effects of all semi-natural land covers, i.e. grassland (largest at the landscape-scale, 1000 m), forests (largest at intermediate scales, 250 m), and wetlands (largest at the local-scale, 50 m). The negative association of insect biomass with urban land cover and positive association with farmland were not clearly modified by any variable associated with land use intensity. Our results show that land cover has an impact on flying insect biomass with the magnitude of this effect varying across spatial scales. Since we consistently found negative effects of urban land cover, our findings highlight the need for the conservation of semi-natural areas, such as wetlands, grasslands and forests, in Europe.