Invertebrate biodiversity continues to decline in cropland

Spillovers and legacies of land management on temperate woodland biodiversity

Species distributions are a product of both current spatial configuration of habitats and legacies of historical land use. Here we explore current and historical drivers of species distributions, considering combined effects of spatial spillovers and temporal legacies, both within and between habitat types. We fit Bayesian hierarchical occupancy models to data on 373 species from four taxa (ground beetles, birds, vascular plants and small terrestrial mammals) from a chronosequence of 134 woodlands (10 to >250 years old) in temperate agricultural landscapes in the UK. Both spillovers and legacies affect species richness and community composition and, critically, these effects interact. Real-world combinations of spillovers and legacies result in different biodiversity responses compared with the individual factors in isolation. Woodland patches in landscapes with more old woodland and lower amounts of historical woodland loss tend to host more bird and plant but fewer beetle species. Failing to account for these drivers (in particular, legacy effects) gives a distorted view of habitat suitability. In consequence, the same management actions may result in unexpectedly different outcomes depending on the spatial and historical context within the landscape. A better understanding of spillovers and legacy effects on species distributions is required to design biodiversity-friendly, cost-effective land management.

Disentangling the effects of habitat loss and fragmentation on a highly diverse European wildlife

Habitat loss and fragmentation are among the main threats to global biodiversity and ecosystem services. While the effects of habitat loss on fauna are mostly negative, the responses of animals to fragmentation are varied. The frequency of negative impacts of both processes ultimately depends on taxonomic and functional diversity, the different landscape metrics, and the biological responses considered (e.g. species assemblage, behaviour, genetics). A systematic literature review was conducted to evaluate the impacts of habitat loss, fragmentation and associated landscape metrics on the terrestrial fauna of peninsular Spain, a biodiversity hotspot in Europe. Our database included 107 articles and 1942 cases of the effects (positive, negative or neutral) of habitat loss, fragmentation or a given landscape metric on a biological response in four taxa of vertebrates (amphibians, reptiles, birds and mammals) and six of invertebrates (tardigrades, annelids, springtails, insects, myriapods and arachnids). Habitat loss mostly showed negative impacts, whereas the effects of fragmentation were diverse. Patch size reduction was the most detrimental landscape metric, while matrix contrast and edge effect reduced negative impacts and/or increased positive effects. Relative to the biological responses, richness showed a significantly higher proportion of negative effects, in contrast to positive interactions and behaviour. Vertebrates were more negatively affected than invertebrates by both habitat loss and fragmentation, although matrix contrast caused more negative effects on invertebrates. Behaviour also showed an increase in negative impacts and a decrease in positive impacts in invertebrates compared to vertebrates. The results highlight the dependence on ecological and taxonomic context of the impacts of habitat loss and fragmentation on animal communities. Comparative approaches are required to improve our understanding of the effects of these processes, enabling well-supported conservation actions. Under the challenging scenario of global change and biodiversity crisis, our findings may stimulate similar analyses in different regions of the globe.

Global impacts of exotic eucalypt plantations on wildlife

The establishment of exotic tree plantations poses a pervasive threat to wildlife across the globe. Among the most important tree species used for forestry purposes worldwide are members of the genus Eucalyptus, which have now been established in at least 107 countries outside of their native range. When introduced into non-native areas, eucalypt plantations are associated with myriad novel challenges for native fauna, and have often been associated with reductions in the biodiversity of local communities. However, similar to other anthropogenic habitats, eucalypt plantations can also create novel opportunities for species that can allow them to survive and thrive in these novel environments. In this review, we use eucalypt plantations as a case study for understanding the ecological and evolutionary responses of wildlife to anthropogenic habitat loss and change. We begin by summarising the main avenues of research addressing the study of wildlife responses at the individual, community, and ecosystem levels, and highlight critical research gaps. We also consider the characteristics of different types of eucalypt plantations and how such attributes are linked with the ability of animals to respond appropriately to the establishment of plantations, and summarise important considerations for the conservation of animal communities in these human-altered habitats.

Integrating Network and Meta-Ecosystem Models for Developing a Zoogeochemical Theory

Human activities have caused significant changes in animal abundance, interactions, movement and diversity at multiple scales. Growing empirical evidence reveals the myriad ways that these changes can alter the control that animals exert over biogeochemical cycling. Yet a theoretical framework to coherently integrate animal abundance, interactions, movement and diversity to predict when and how animal controls over biogeochemical cycling (i.e., zoogeochemistry) change is currently lacking. We present such a general framework that provides guidance on linking mathematical models of species interaction and diversity (network theory) and movement of organisms and non-living materials (meta-ecosystem theory) to account for biotic and abiotic feedback by which animals control biogeochemical cycling. We illustrate how to apply the framework to develop predictive models for specific ecosystem contexts using a case study of a primary producer-herbivore bipartite trait network in a boreal forest ecosystem. We further discuss key priorities for enhancing model development, data-model integration and application. The framework offers an important step to enhance empirical research that can better inform and justify broader conservation efforts aimed at conserving and restoring animal populations, their movement and critical functional roles in support of ecosystem services and nature-based climate solutions.

Evidence for bottom-up effects of moth abundance on forest birds in the north-boreal zone alone

Insect declines are raising alarms regarding cascading effects on ecosystems, especially as many insectivorous bird populations are also declining. Here, we leveraged long-term monitoring datasets across Finland to investigate trophic dynamics between functional groups of moths and birds in forested habitats. We reveal a positive association between the biomass of adult- or egg-overwintering moths and the biomasses of resident and long-distance migrant birds reliant on caterpillars as breeding-season food in the north-boreal zone. Contrary to expectations, similar signs of moth bottom-up effects on insectivorous birds were not observed in other Finnish regions or for moths overwintering in other life stages. In fact, some negative associations between moths and birds were even detected, possibly attributable to opposite abundance trends. While supporting the existence of bottom-up effects in the north-boreal zone, our study emphasizes the need for further investigation to elucidate moth-mediated trophic dynamics in areas characterized by the insect decline.

Significant improvement in freshwater invertebrate biodiversity in all types of English rivers over the past 30 years

There remains a persistent concern that freshwater biodiversity is in decline and being threatened by pollution. As the UK, and particularly England, is a densely populated nation with rivers of modest dilution capacity, this location is very suitable to examine how freshwater biodiversity has responded to human pressures over the past 30 years. A long-term dataset of 223,325 freshwater macroinvertebrate records from 1989 to 2018 for England was retrieved and examined. A sub-set of approximately 200 sites per English Region (1515 sites in total with 62,514 samples), with the longest and most consistent records were matched with predicted wastewater exposure, upstream land cover and terrain characteristics (latitude, altitude, slope gradient and flow discharge). To understand changes in macroinvertebrate diversity and sensitivity with respect to these parameters, the biotic indices of (i) overall family richness, (ii) Ephemeroptera, Plecoptera, Trichoptera (EPT) family richness, and (iii) the Biological Monitoring Working Party (BMWP) scores of NTAXA (number of scoring taxa) and (iv) ASPT (average score per taxon) were selected. A review of how close the BMWP scores come to those expected at minimally impacted reference sites was included. For all latitudes, altitudes, channel slope, river size, wastewater exposure levels, and differing proportions of upstream woodland, seminatural, arable and urban land cover, all diversity or sensitivity indices examined improved over this period, although this improvement has slowed in some cases post 2003. Mean overall family richness has increased from 15 to 25 family groups, a 66 % improvement. The improvement in mean EPT family richness (3 to 10 families, >300 % improvement), which are considered to be particularly sensitive to pollution, implies macroinvertebrate diversity has benefited from a national improvement in critical components of water quality.