Climate change and habitat loss present serious threats to nature. Yet, due to a lack of historical land-use data, the potential for land-use change and baseline land-use conditions to interact with a changing climate to affect biodiversity remains largely unknown. Here, we use historical land use, climate data and species observation data to investigate the patterns and causes of biodiversity change in Great Britain. We show that anthropogenic climate change and land conversion have broadly led to increased richness, biotic homogenization and warmer-adapted communities of British birds, butterflies and plants over the long term (50+ years) and short term (20 years). Biodiversity change was found to be largely determined by baseline environmental conditions of land use and climate, especially over shorter timescales, suggesting that biodiversity change in recent periods could reflect an inertia derived from past environmental changes. Climate–land-use interactions were mostly related to long-term change in species richness and beta diversity across taxa. Semi-natural grasslands (in a broad sense, including meadows, pastures, lowland and upland heathlands and open wetlands) were associated with lower rates of biodiversity change, while their contribution to national-level biodiversity doubled over the long term. Our findings highlight the need to protect and restore natural and semi-natural habitats, alongside a fuller consideration of individual species’ requirements beyond simple measures of species richness in biodiversity management and policy.

At least 10% of the world’s tree species are threatened with extinction and pathogens are increasingly implicated in tree threats. Coextinction and threats to affiliates as a consequence of the loss or decline of their host trees is a poorly understood phenomenon. Ash dieback is an emerging infectious disease causing severe dieback of common ash Fraxinus excelsior throughout Europe. We utilized available empirical data on affiliate epiphytic lichen diversity (174 species and 17,800 observations) among 20 ash dieback infected host tree populations of F. excelsior on the island Gotland in the Baltic Sea, Sweden. From this, we used structured scenario projections scaled with empirical data of ash dieback disease to generate probabilistic models for estimating local and regional lichen coextinction risks. Average coextinction probabilities (Ā) were 0.38 (95% CI ±0.09) for lichens occurring on F. excelsior and 0.14 (95% CI ±0.03) when considering lichen persistence on all tree species. Ā was strongly linked to local disease incidence levels and generally increasing with lichen host specificity to F. excelsior and decreasing population size. Coextinctions reduced affiliate community viability, with significant local reductions in species richness and shifts in lichen species composition. Affiliates were projected to become locally extirpated before their hosts, illuminating the need to also consider host tree declines. Traditionally managed open wooded meadows had the highest incidence of ash dieback disease and significantly higher proportions of affiliate species projected to go extinct, compared with unmanaged closed forests and semi-open grazed sites. Most cothreatened species were not previously red-listed, which suggest that tree epidemics cause many unforeseen threats to species. Our analysis shows that epidemic tree deaths represent an insidious, mostly overlooked, threat to sessile affiliate communities in forested environments. Current conservation and management strategies must account for secondary extinctions associated with epidemic tree death.

Low‐productivity forests are often the last remaining pristine forests in managed forest landscapes and typically overrepresented among protected forests. However, the provisioning of individual and multiple ecosystem services (ES‐multifunctionality) by these forests remains poorly assessed, making it difficult to evaluate their importance in forest conservation and management. Here, using nationwide data on ES from over 2,000 forest plots, we test whether levels of ES‐multifunctionality and individual ES differ between low‐productivity forested mires and rocky outcrops in relation to the levels of productive forests, and as a function of forest age, tree species richness and climate. We defined ES‐multifunctionality using different threshold values of the maximum levels (low, medium and high) and weighted these according to land‐use objectives (equal weight of all services, greater weight to cultural and supporting ES or greater weight to production). We show that the ES‐multifunctionality of forested mires is consistently lower than those of productive forests. However, the ES‐multifunctionality increased with forest age in forested mires but not in productive forests. The ES‐multifunctionality of forested rocky outcrops, on the other hand, was higher or equivalent to that of productive forests under equal weight and supporting land‐use objectives, respectively. Our findings highlight that forested rocky outcrops can supply multiple ES, especially older forested stands with mixtures of coniferous and deciduous trees. Generally, we found no evidence for strong trade‐offs between the ES studied and our results highlight the importance of forest age for increasing the ES‐multifunctionality of low‐productivity forests. Synthesis and applications. Low‐productivity forests should not be exempt of forestry or protected purely based on low productivity or low land‐use conflict if the goal is to conserve multiple ecosystem services (ES). Inclusion grounds for protecting low‐productivity forests should instead carefully consider the site type (dry vs. wet), forest age and tree species richness. To maintain higher ES‐multifunctionality in low‐productivity forests, older or deciduous trees should also not be harvested. This will require changes in current conservation or management policies of low‐productivity forests of some countries.