The ongoing biodiversity crisis is a major concern, with future biodiversity losses predicted to reduce ecosystem resilience. Climate change and habitat loss are considered the primary drivers of global biodiversity loss and the reorganization of ecological communities. Since the early 20th century, agricultural and forestry intensification across Europe has been linked to biodiversity decline and homogenization of species assemblages. Simultaneously, global climate warming has caused shifts in species ranges. However, the interaction between climate and land-use change on biodiversity remains largely unknown due to a lack of historical land-use data. This study addresses this gap by investigating the combined effects of climate change and land-use change on biodiversity in Great Britain, considering both short-term (20 years) and long-term (50+ years) changes. The research utilizes a comprehensive national-scale dataset combining historical land-use, climate data (average mean annual temperature and precipitation), and species observation data at a 10 km grid cell resolution for birds, butterflies, and plants. The study aims to identify patterns and causes of biodiversity change, quantify the individual and interacting effects of climate and land-use change, examine the role of baseline environmental conditions, and determine the association between environmental characteristics and local contributions to national-level biodiversity. Understanding these factors is crucial for effective biodiversity management and conservation strategies.

Previous research has extensively documented the negative impacts of agricultural and forestry intensification on biodiversity, resulting in declining species richness and homogenization of species assemblages across various taxonomic groups and spatial scales. Studies have shown a strong correlation between these land-use changes and the loss of biodiversity and the creation of homogenous species assemblages. Similarly, numerous studies have highlighted the effect of climate change on biodiversity, with species’ ranges shifting towards higher latitudes and altitudes in response to warming temperatures. However, most research has focused on either climate change or land-use change in isolation. The interaction between the two drivers, particularly their combined effect on biodiversity, remains less well understood, especially at larger temporal scales. The scarcity of high-quality historical land-use data and the difficulties in conducting long-term studies has hindered research into these complex interactions. This study addresses this knowledge gap by leveraging existing datasets and sophisticated analytical methods to explore these synergistic and antagonistic effects of climate and land-use change.

This study compiled a comprehensive dataset of land use, climate, and species observations at a 10 km grid cell resolution in Great Britain. The data covered three time periods: the 1960s, 1990s, and 2010s, enabling the analysis of both short-term (1990s-2010s) and long-term (1960s-2010s) changes. The species data, sourced from atlases and monitoring programs, were presence-only data with uneven recording effort. The Frescalo approach was used to estimate recorder effort for each taxon and time period to account for spatiotemporal variation in recording intensity. Three biodiversity metrics were calculated for each taxon, time period, and grid cell: species richness, beta diversity (measuring biotic homogenization), and community temperature index (CTI, indicating community adaptation to warmer climates). Land-cover data from the Land Utilisation Survey of Great Britain (1930s-1940s), the 1990 Land Cover Map, and the 2015 Land Cover Map were used to assess land-use changes, categorizing land cover into arable land, semi-natural grasslands, improved grasslands, forest, and urban areas. Climate data (annual mean temperature and total annual precipitation) were obtained from the Met Office, UK. A proxy for microclimatic heterogeneity, based on solar index values from a digital elevation model, was also included. Statistical analyses involved generalized linear mixed-effects models (GLMMs) and linear mixed-effects models (LMMs) to investigate differences in biodiversity between time periods and associations between biodiversity change and environmental changes (climate and land use), their interactions, and baseline environmental conditions. Spatial autocorrelation was accounted for using spatially structured random effects. To address collinearity, sequential regression analysis was employed. Furthermore, a tenfold cross-validation technique was used to evaluate model robustness in estimating fixed effects.

The study found that species richness increased across all three taxa (birds, butterflies, and plants) over both the long and short terms. Biotic homogenization, as indicated by decreased beta diversity, was observed, except for birds which showed increased beta diversity in the long term. All three taxa exhibited a long-term increase in CTI, reflecting a shift towards warmer-adapted communities. Surprisingly, butterflies showed a short-term decrease in CTI despite overall climate warming. Analyses of the drivers of biodiversity change revealed that increases in species richness and biotic homogenization were generally associated with increased temperature, precipitation, and anthropogenic land uses, especially in the long term. The expansion of agriculturally improved grasslands, forests, urban areas, and arable land occurred largely at the expense of semi-natural grasslands. Baseline conditions of land use and climate significantly influenced biodiversity change, particularly in the short term. Grid cells with higher baseline semi-natural grassland cover showed lower rates of species richness increase and biotic homogenization. Wetter and colder baseline conditions promoted stability in some taxa. Baseline biodiversity levels also strongly affected biodiversity change, with higher baseline richness associated with lower richness increases, and higher baseline beta diversity with greater decreases in beta diversity. Microclimatic heterogeneity was associated with larger increases in plant and butterfly richness and a decrease in bird CTI. Analysis of local contributions to national beta diversity showed that semi-natural grasslands had the largest positive effect size, with their contribution to national biodiversity doubling over the long term. The positive association of semi-natural grassland cover with local contribution to beta diversity was notably increasing over time.

The findings confirm the association between climate and land-use change and biodiversity reorganization across multiple taxa over both long and short timescales. The observed increase in species richness, despite overall biodiversity loss, could be attributed to the expansion of species already adapted to human-modified landscapes, along with climate change driving range expansions. The strong influence of baseline environmental conditions on short-term biodiversity changes suggests inertia, where communities continue to reorganize in response to past environmental changes. The importance of semi-natural grasslands in maintaining biodiversity stability is highlighted, with these habitats showing lower rates of biodiversity change and increasing contribution to national beta diversity over time. The interaction between climate change and land-use change has complex effects on biodiversity, with varying synergistic and antagonistic interactions across taxa and metrics. This underscores the need to go beyond simple measures of species richness and consider species-specific responses to environmental change in conservation efforts. The relatively low proportion of biodiversity change explained by climate and land-use change in the models suggests the influence of other factors, such as land-use intensification, topography, species functional traits, and epigenetic mechanisms.

This study demonstrates the significant impact of anthropogenic climate and land-use change on biodiversity in Great Britain. Despite being highly degraded, semi-natural grasslands play a crucial role in maintaining biodiversity stability and should be prioritized for protection, conservation, and restoration. The complex interactions between climate change and land use highlight the need for comprehensive conservation strategies that account for species-specific responses and go beyond simple measures of species richness. Future research should investigate the influence of other factors, such as land-use intensification, topography, species functional traits, and epigenetic mechanisms, on biodiversity change.

The study's use of presence-only data with uneven recording effort, despite efforts to correct for this, could introduce some bias. The 10 km grid cell resolution might not capture fine-scale changes in biodiversity. The historical land-use data predate some of the species data, which could influence the interpretation of baseline conditions. While the study considers the interactions between climate change and land-use change, other factors influencing biodiversity dynamics might not have been fully accounted for.