Insects make up the majority of all animal species, with 70% occurring in the tropics ¹ , yet the impacts of warming on tropical insects remain highly uncertain ² . This stems from sparse, taxonomically biased data on thermal tolerance of tropical insects and an incomplete understanding of the underlying physiological mechanisms ³ . Here we compared environmental temperatures with field-measured upper and lower thermal tolerance limits of around 2,300 insect species along Afrotropical and Neotropical elevational gradients and identified genomic signatures of thermal tolerance across the insect tree of life. We show that thermal tolerances do not proportionally track environmental temperatures but approach an asymptote in tropical lowlands. Insects at high elevations utilize plasticity to cope with rising temperatures, whereas lowland species have limited plastic abilities. Heat tolerance showed strong differences among insect orders and families, reflected in the thermal stability of proteins, suggesting that variation in thermal tolerance is founded in the fundamental protein architecture. Up to 52% of future surface temperatures and 38% of air temperatures in the Amazonian lowlands can cause heat mortality in half of the studied community. Our data suggest a limited capacity of insects in the Earth’s most biodiverse regions to buffer future warming.

Natural disturbances are increasing around the globe, also impacting protected areas. Although previous studies have indicated that natural disturbances result in mainly positive effects on biodiversity, these analyses mostly focused on a few well established taxonomic groups, and thus uncertainty remains regarding the comprehensive impact of natural disturbances on biodiversity. Using Malaise traps and meta‐barcoding, we studied a broad range of arthropod taxa, including dark and cryptic taxa, along a gradient of bark beetle disturbance severities in five European national parks. We identified order‐level community thresholds of disturbance severity and classified barcode index numbers (BINs; a cluster system for DNA sequences, where each cluster corresponds to a species) as negative or positive disturbance indicators. Negative indicator BINs decreased above thresholds of low to medium disturbance severity (20%–30% of trees killed), whereas positive indicator BINs benefited from high disturbance severity (76%–98%). BINs allocated to a species name contained nearly as many positive as negative disturbance indicators, but dark and cryptic taxa, particularly Diptera and Hymenoptera in our data, contained higher numbers of negative disturbance indicator BINs. Analyses of changes in the richness of BINs showed variable responses of arthropods to disturbance severity at lower taxonomic levels, whereas no significant signal was detected at the order level due to the compensatory responses of the underlying taxa. We conclude that the analyses of dark taxa can offer new insights into biodiversity responses to disturbances. Our results suggest considerable potential for forest management to foster arthropod diversity, for example by maintaining both closed‐canopy forests (>70% cover) and open forests (<30% cover) on the landscape.

Tropical old‐growth forests continue to decline worldwide, resulting in a huge loss of biodiversity. The extent to which the expansion of second‐growth forests can counteract biodiversity loss is context‐dependent and controversial. To test the recovery of bird communities along a gradient from active pastures and cacao plantations, through regenerating forest on land last used for agriculture between 1 and 38 years ago, to old‐growth forest, we sampled simultaneous audio recordings from 66 plots, from which an expert identified all bird species detected at fixed time points throughout the day. The study area is characterized by typical small‐scale agriculture with remnant trees in the Ecuadorian Chocó Forest. To quantify different aspects of biodiversity, we used incidence‐based Hill numbers focusing on infrequent, frequent and highly frequent species in taxonomic, functional and phylogenetic diversity, considering sample coverage (an objective measure of sample completeness). Bird community composition changed with the regrowth gradient represented on the first axis of the ordination. Differences in bird communities were also very robust to changes in sample coverage. The sample coverage decreased significantly along the recovery gradient and affected the different measures of alpha diversity. Although the results controlled by sample coverage showed no change in taxonomic and phylogenetic diversity, the functional diversity of infrequent, frequent and highly frequent species decreased along the recovery gradient. Cacao plantations exhibited particularly high diversity values, highlighting the potential of these patches to support woodland and shrubland species in agriculture. Furthermore, several forest species regularly used the agricultural areas, attracted by remnant trees characteristic of the small‐scale agricultural landscape in our study region. Synthesis and applications. Our results highlight the importance of standardizing biodiversity measures and incorporating beta diversity in biodiversity monitoring. We demonstrate that taxonomic, phylogenetic and functional bird diversity can be high in secondary forests within smallholder agricultural landscapes. This underscores the potential for natural forest recovery, particularly when recovery patches are embedded within a forest matrix that includes old‐growth stands.

In recent years, climate change has caused an unprecedented wave of tree mortality across Europe, reshaping forest canopy cover and deadwood structures. Nevertheless, the effects of tree mortality on species‐rich groups, such as insects are still unclear, mainly because few replicated disturbance experiments exist and most studies focus on small taxonomic subsets of the species‐rich class of insects, both of which prevent generalization. To disentangle the effects of canopy cover and deadwood on total above‐ground insect diversity collected with Malaise traps, we experimentally applied different disturbance treatments in 11 commercial forests throughout Germany. We quantified taxonomic (TD) and phylogenetic diversity (PD) among 22,889 operational taxonomic units from 362 insect families along Hill numbers (q = 0, 1, 2) using metabarcoding, and standardized diversities by sample coverage as an objective measure of sample completeness. Our results showed a systematically lower sample coverage in canopy gaps compared with closed canopy forests, highlighting that the true diversity in open forest habitats is underestimated in bulk samples if sample coverage is not considered. Controlled for sample coverage, TD increased by up to 47% in canopy gaps with deadwood, compared with controls under closed canopy and without deadwood. The increase in TD was accompanied by a similar increase in PD only in rare species (q = 0), underlining the gain in evolutionary diverse communities of rare species, but redundancy in dominant species (q = 2). Synthesis and applications. Our experiment provides strong evidence for the importance of clustered tree mortality for comprehensive insect diversity in temperate forests and highlights the potential of forest management to enhance insect diversity in homogeneous commercial forests, particularly through the creation of canopy gaps and the retention of deadwood. Both mimic natural dynamics and can support rare species along with the ecosystem functions they may provide.