Helen C. Wheeler

Background: Land management practices have significant impacts on biodiversity and climate change processes. Conservation and rewilding practitioners are increasingly seeking to enhance ecosystem functions and carbon sequestration simultaneously, encouraged by climate policies such as the European Green Deal. In recent years, ecosystem restoration involving large herbivores (≥ 10 kg) has attracted growing interest. However, the climate impacts of large herbivores are complex, including direct and indirect impacts from greenhouse gas (GHG) emissions, carbon storage, wildfire and albedo. These impacts can have cooling or warming effects and vary with species, herd density, season and habitat. To date, the diverse research on this topic has not been collated and categorised in a systematic map. Here, we present a systematic map of research on the climate effects of large herbivores in European terrestrial habitats, highlighting research distribution, clusters and gaps, and the potential for further quantitative analyses. We address the primary question of what research exists on the climate effects of large herbivores in Europe. Methods: Following our pre-published protocol, we used a pre-defined search string to conduct a search of peer-reviewed and grey literature, using a range of bibliographic databases, search engines and websites. We screened search results for relevance in two stages: by title and abstract, then full text. We excluded articles that failed to meet the eligibility criteria of terrestrial habitats in Europe (Population), large herbivores (Exposure) and climate impacts (Outcome). We coded the included studies by multiple variables, recorded in a spreadsheet alongside the narrative synthesis. Review findings: We identified 316 articles for inclusion, involving a total of 565 studies (different research comparisons within the same article). Most studies were conducted in Northern Europe (63%), with the largest research cluster in the United Kingdom. Eastern Europe had the fewest studies (6%). The most frequently studied large herbivores were cattle (included in 54% of studies), sheep (34%) and reindeer (7%). Other types of large herbivores were included in fewer than 5% of studies (these included goats, equines, various species of wild cervids, European bison, pigs, wild boars, goat-antelopes (chamois), water buffaloes, beavers, and tortoises). The most frequently studied climate-related outcomes were soil carbon (included in 34% of studies), nitrous oxide (N ₂ O) emissions (33%), carbon dioxide (CO ₂ ) flux or emissions (21%) and enteric methane (CH ₄ ) emissions (17%). Few studies combined multiple climate-related effects to estimate net emissions (6%). Conclusions: The systematic map demonstrates substantial research gaps on the climate impacts of large herbivores. Research has predominantly focused on large domestic herbivores in agricultural contexts, particularly cattle and sheep. The research gaps for other large herbivores (and for natural and semi-natural habitats) present difficulties for conservation and rewilding practitioners in assessing the climate implications of their choices regarding large herbivores used in land management. The paucity of studies addressing net GHG emissions (accounting for multiple GHGs and carbon sequestration) also present challenges for determining which choices are likely to have net climate benefits. These research gaps have implications for policy and practice, particularly for nature-based carbon offsetting projects. Research to address these gaps would aid decision-making in both nature recovery and climate change mitigation.

Background: As the global climate rapidly warms, one pervasive impact is the “borealisation” of the Arctic. Borealisation occurs when the species, communities and ecological processes of the Arctic transform to resemble that of more boreal lower latitudes. Such change is likely to have profound impacts on the diverse communities and cultures of the Arctic. Some of these impacts are starting to be documented, however this evidence has not been synthesised systematically. This systematic map protocol will therefore address the research question: “What evidence exists on the interlinkages between ecological and societal impacts of borealisation of the Arctic?” Additionally, this systematic map will support two current assessments of the Arctic Council working groups on the societal and ecological impacts of climate change in the Arctic, thus responding to policy relevant questions posed by Arctic governments. Methods: Following guidelines set out by the Collaboration for Environmental Evidence (CEE), a search of literature, both peer reviewed and grey, will be performed using a range of bibliographic databases, websites and search engines. The search strategy will use a pre-defined search string with Boolean operators. The search results will be screened for relevance according to specific inclusion and exclusion criteria. This will be done in two stages – firstly a screen of titles and abstracts, then a full text screening of eligible articles. At both stages, articles will be excluded if they fail to meet all eligibility criteria or if they meet exclusion criteria. Next, articles that are eligible after full text screening will be coded. At both the screening and coding stages, two reviewers will independently assess a defined number of articles to ensure inter-reviewer reliability and resolve differences. This evidence will then form a searchable database with accompanying visual outputs. A narrative output will outline the range and distribution of evidence, identify potential bias, knowledge clusters and gaps, and will explore areas for further research.

Attention to epistemological relationships between Indigenous and local knowledges (ILK) and conservation science is increasing. Some approaches for doing so have been developed, but in general, serious engagement between ILK and science still feels experimental and does not have broad uptake. Here we address some of the main issues that arise when considering the epistemological relationships between ILK and conservation or ecological science. A key issue is the relationship between ILK and science that sets the expectations for how they may form dialogues, collaborations, or co-production. After reviewing several perspectives on this relationship, and their limitations, we suggest that a focus on shared meanings within an ‘ethic of equivocation’ is a productive path forward. In an ethic of equivocation, neither ILK nor science validates the other, yet meaning can be created. We explain and develop the concepts of meanings and equivocation in the ILK-science context. We, thus, argue for a broad and rich understanding of the joint roles of ILK and science, which goes beyond treating ILK as a data source. We argue that diverse styles of reasoning exist in science, and scientists may already treat observations, models, and collaborations in the ways that we discuss, providing ready-made analogies for thinking about ILK. We also discuss how to avoid abuses of power while engaging with ILK to co-produce new knowledge.

In the past decades, agricultural land abandonment and declining land-use intensity became common, especially in the Mediterranean countries of Southern Europe. In some areas this development opened up possibilities for rewilding and the recolonization or expansion of large mammal populations. Yet, in some instances, co-occurrence of wild mammals and free-ranging domestic herbivores might lead to potential conflicts. It is therefore necessary to study the ecological interactions between wild and domestic mammal species to understand the effects of land abandonment and rewilding on biodiversity and ecosystem services. Camera traps are an effective tool for studying species interactions and occupancy dynamics as they allow for long-term monitoring with minimal interference. We conducted a long-term monitoring program with camera traps in the Peneda-Gerês National Park in Northern Portugal. The area has undergone large land-use changes following the abandonment of agricultural areas in the past 60 years. While agro-pastoral activities, especially the breeding of free-ranging horses and cattle, are still common in the area, the intensity of these activities has decreased significantly, promoting natural succession and an increase or return of several large mammal species in recent years. Our project aims at (1) assessing the population trends of the medium and large sized mammals in the area over time; (2) analyzing the effects of passive rewilding on occurrence, abundance and behavior; and (3) understanding potential interactions or conflicts between wild and domestic herbivores. Our publication provides a dataset from long-term camera trap monitoring in the Peneda-Gerês National Park between 2015 and 2021. We established a 16 km² grid of 64 cameras deployed yearly during the summer months. In this paper we publish the data and images collected between 2015 and 2021, using both the Camtrap DP standard and the GBIF Darwin Event Core. We obtained a total of 934,810 pictures on 41,234 trap nights. The pictures were automatically grouped into sequences with each sequence representing a distinct occurrence event, resulting in 80,191 occurrences. Out of those, 14,442 contained observations of a species, while the remaining were either blank or the species was not identifiable. We only obtained the information concerning whether a species was present or absent on a picture, disregarding the number of individuals. Most observations were of domestic cattle (Bos taurus) and horses (Equus caballus) followed by European roe deer (Capreolus capreolus) and wild boar (Sus scrofa). Further observations include red fox (Vulpes vulpes), gray wolf (Canis lupus), Eurasian badger (Meles meles), stone marten (Martes foina), common genet (Genetta genetta), Iberian ibex (Capra pyrenaica) and red deer (Cervus elaphus). We estimated occupancy and densities for the most common species. The project is on-going and additional data will be included in the future. The dataset is freely available for ecological analysis but also for training machine learning systems in automated image classification as all pictures have been manually classified.