Climate change, land use conflicts, predation and ecological degradation as challenges for reindeer husbandry in northern Europe: what do we really know after half a century of research?

Climate change adaptation stories: Co-creating climate services with reindeer herders in Finland

Reindeer husbandry in the Arctic region is strongly affected by the local climate. Reindeer herders are used to coping with adverse weather, climate, and grazing conditions through autonomous adaptation. However, today's rapidly changing Arctic environment poses new challenges to the management of herding activities. Finding means for combining traditional and scientific knowledge without depriving any of the systems of its fundamental strengths is hence deemed necessary. In this work, we apply a transdisciplinary framework for knowledge co-production involving international researchers and reindeer herders from different cooperatives in northern Finland. Through 'climate change adaptation stories', we co-explore how climate predictions can inform herders' decision making during the herding season. Relevant decisions include the anticipation of summer harvest time, the inopportune periods of cold weather in spring, and insect harassment in summer. Despite their potential benefits for climate-sensitive decisions, climate predictions have seen limited uptake, mainly due to their probabilistic nature and lower quality compared with shorter-term weather forecasts. The analysis of two different adaptation stories shows that seasonal predictions of temperature for May and June can successfully advise about the likelihood of having an earlier than normal harvest. This information can be obtained up to three months in advance, helping herders to better arrange their time for other activities. Likewise, sub-seasonal predictions of temperature during April and May can be useful to anticipate the occurrence of backwinter episodes, which can support herders in deciding whether to feed reindeer in pens for longer, avoiding putting the survival of calves at risk. This study, which would benefit from co-evaluation in real world settings and consideration of additional adaptation stories, sets the basis for a successful co-production of climate services with Arctic reindeer herders. This research shows the potential to enhance the resilience of Polar regions, offering opportunities for adaptation while supporting the sustainability and culture of traditional practices of Arctic communities.

Investigating the domestication and early management of reindeer (Rangifer tarandus) in the Sámi archaeological context from teeth geometric morphometrics

For centuries, reindeer herding has been an integral part of the subsistence, lifeways, economy and cosmology of the Sámi of northern Fennoscandia. Despite its importance, the timing and details of early reindeer domestication are still highly debated. Identifying domesticated individuals in the archaeological record remains complicated due to the presence of two interbreeding subspecies in Fennoscandia and a mixed socio-economic organisation by Sámi populations, which was mainly a combination of wild reindeer hunting and small-scale reindeer herding. This study proposes methodological improvement for identifying domestic individuals using 2D landmark and sliding semi-landmark based geometric morphometrics on the isolated lower molars of 389 modern specimens, and 90 teeth from four archaeological sites in Finnish Lapland. Our results indicate that despite the significant impact of wear on overall tooth morphology, our protocol is very useful for identifying subspecies (classification accuracy of the two species is between 78 and 91% depending on the wear class) and understanding the morphological changes induced by the domestication process. We suggest that the morphological variation observable among modern populations has been impacted by recent changes in herding strategies in northern Fennoscandia, and that the archaeological domesticated reindeer populations were relatively different, probably due to selection by the Sámi. This study also highlights the importance of using other direct evidence or contextual archaeological data to better trace the early evidence of a domesticated reindeer economy in northern Fennoscandia, and aid in reconstructing the socio-economic changes in Sámi populations over time.

Winter condition variability decreases the economic sustainability of reindeer husbandry

Wild and semidomesticated reindeer are one of the key species in Arctic and subarctic areas, and their population dynamics are closely tied to winter conditions. Difficult snow conditions have been found to decrease the calving success and survivability of reindeer, but the economic effects of variation in winter conditions on reindeer husbandry have not been studied. In this study, we combine state-of-the-art economic-ecological modeling with the analysis of annual reindeer management reports from Finland. These contain local knowledge of herding communities. We quantify the occurrence probabilities of different types of winters from annual management reports and analyze the effects of this variation in winter conditions on reindeer husbandry using an age- and sex-structured bioeconomic reindeer-lichen model. Our results show that difficult winters decrease the net revenues of reindeer husbandry. However, they also protect lichen pastures from grazing, thereby increasing future net revenues. Nonetheless, our solutions show that the variability of winter conditions overall decrease the net income of herders compared to constant winter conditions. Low lichen biomass appears to make reindeer management more sensitive to the effects of difficult winter conditions. We also found that it is economically sensible to use supplementary feeding during difficult winters, but the net revenues still decrease compared to average winters because of the high feeding costs. Overall, our analysis suggests that the increasing variability of winter conditions due to climate change will decrease net revenues in reindeer husbandry. This decrease will still occur even if the most extreme effects of climate change do not occur. This study shows that combining a state-of-the-art bioeconomic model and practitioner knowledge can bring compatible insights, ideas, results, and a bottom-up perspective to the discussion.

Maps and stories in the creation of richer accounts of change in pastoral landscapes in Nordland, northern Norway

The categories and concepts in the existing official land-use maps have been under improvements over recent years; however, this study from Nordland, northern Norway, shows that they continue to pose several dilemmas when aiming to better capture the impacts of multiple land uses on reindeer herding. While these developments have done much to better communicate the presence of reindeer herding to developers and planners, there remain significant challenges to achieve best practices. In particular, the confluence of multiple landscape features, for instance, roads, farmland, ecoregions, tenure, pastures, tourism paths and cabins, may have interactions that create cumulative impacts that do not “add up” neatly across map layers. Migration routes, herding routes, and resting areas have been introduced in these maps. In collaboration with reindeer herders, this article analyses how to enrich mapping practices by for example including bottlenecks, parallel to increased attention to influence zones and avoidance zones, as important emergent impacts of multiple interacting features of the landscape. Our research reveals how local knowledge developed by herders through their “presence in the landscape” is better capable of accounting for interactions and cumulative dimensions of landscape features. Through our participatory mapping approach with Sámi reindeer herders, we focus on ways of combining reindeer herders’ knowledge and GIS maps and demonstrate the potential in collaborative work between herders and policymakers in generating a richer understanding of land-use change. We conclude that the practical knowledge of people inhabiting and living with the landscape and its changing character generates a rich understanding of cumulative impacts and can be harnessed for improved land-use mapping and multi-level governance.

Mapping cumulative pressures on the grazing lands of northern Fennoscandia

Traditional grazing areas in Europe have declined substantially over the last century. Specifically, in northern Fennoscandia, the grazing land is disturbed by cumulative land-use pressures. Here we analysed the configuration of the grazing land for reindeer and sheep in northern Fennoscandia in relation to the concurrent land-use pressures from tourism, road and railway networks, forestry, industrial and wind energy facilities, together with predator presence and climate change. Our results show that 85% of the region is affected by at least one land-use pressure and 60% is affected by multiple land-use pressures, co-occurring with predator presence and rising temperatures. As such, a majority of the grazing land is exposed to cumulative pressures in northern Fennoscandia. We stress that, if the expansion of cumulative pressures leads to grazing abandonment of disturbed areas and grazing intensification in other areas, it could irreversibly change northern vegetation and the Fennoscandian mountain landscape.

Risk-based surveillance of chronic wasting disease in semi-domestic reindeer

Reindeer pastoralism is a widespread practise across Fennoscandia and Russia. An outbreak of chronic wasting disease (CWD) among wild reindeer (Rangifer tarandus) poses a severe threat to the semi-domestic reindeer herding culture. Establishing surveillance is therefore key, but current models for surveillance of CWD are designed for wild cervids and rely on samples obtained from recreational hunters. Targeting animal groups with a higher infection probability is often used for more efficient disease surveillance. CWD has a long incubation period of 2-3 years, and the animals show clinical signs in the later stages of the infection i.e. 1-4 months prior to death. The semi-domestic reindeer are free-ranging most of the year, but during slaughtering in late fall, herders stress the animals in penned areas. This allows removal of animals with deviant behaviour or physical appearance, and such removals are likely to include animals in the clinical stages of CWD if the population is infected. In Norway, the semi-domestic reindeer in Filefjell is adjacent to a previously CWD infected wild population. We developed a risk-based surveillance method for this semi-domestic setting to establish the probability of freedom from infection over time, or enable early disease detection and mitigation. The surveillance scheme with a scenario tree using three risk categories (sample category, demographic group, and deviations in behaviour or physical appearance) was more effective and less invasive as compared to the surveillance method developed for wild reindeer. We also simulated how variation in susceptibility, incubation period and time for onset of clinical signs (linked to variation in the prion protein gene, PRNP) would potentially affect surveillance. Surveillance for CWD was mandatory within EU-member states with reindeer (2018-2020). The diversity of management systems and epidemiological settings will require the development of a set of surveillance systems suitable for each different context. Our surveillance model is designed for a population with a high risk of CWD introduction requiring massive sampling, while at the same time aiming to limit adverse effects to the populations in areas of surveillance.

The Shrinking Resource Base of Pastoralism: Saami Reindeer Husbandry in a Climate of Change

The productive performance of large ungulates in extensive pastoral grazing systems is modulated simultaneously by the effects of climate change and human intervention independent of climate change. The latter includes the expansion of private, civil and military activity and infrastructure and the erosion of land rights. We used Saami reindeer husbandry in Norway as a model in which to examine trends in, and to compare the influence of, both effects on a pastoral grazing system. Downscaled projections of mean annual temperature over the principal winter pasture area (Finnmarksvidda) closely matched empirical observations across 34 years to 2018. The area, therefore, is not only warming but seems likely to continue to do so. Warming notwithstanding, 50-year (1969–2018) records of local weather (temperature, precipitation and characteristics of the snowpack) demonstrate considerable annual and decadal variation which also seems likely to continue and alternately to amplify and to counter net warming. Warming, moreover, has both positive and negative effects on ecosystem services that influence reindeer. The effects of climate change on reindeer pastoralism are evidently neither temporally nor spatially uniform, nor indeed is the role of climate change as a driver of change in pastoralism even clear. The effects of human intervention on the system, by contrast, are clear and largely negative. Gradual liberalization of grazing rights from the 18th Century has been countered by extensive loss of reindeer pasture. Access to ~50% of traditional winter pasture was lost in the 19th Century owing to the closure of international borders to the passage of herders and their reindeer. Subsequent to this the area of undisturbed pasture within Norway has decreased by 71%. Loss of pasture due to piecemeal development of infrastructure and to administrative encroachment that erodes herders' freedom of action on the land that remains to them, are the principal threats to reindeer husbandry in Norway today. These tangible effects far exceed the putative effects of current climate change on the system. The situation confronting Saami reindeer pastoralism is not unique: loss of pasture and administrative, economic, legal and social constraints bedevil extensive pastoral grazing systems across the globe.

Identifying early stages of reindeer domestication in the archaeological record: a 3D morphological investigation on forelimb bones of modern populations from Fennoscandia

Reindeer herding probably developed during the Late Iron Age onwards and is still an important part of the subsistence and culture of many peoples in northern Eurasia. However, despite the importance of this husbandry in the history of these Arctic people, the period and place of the origin as well as the spread of domestic reindeer is still highly debated. Besides the existence of different breeding methods in these territories, identifying domesticated individuals in the archaeological record is complicated because reindeers are considered to still be in the early phases of the domestication process. Indeed, the traditional morphological markers used in zooarchaeology to decipher the domestication syndrome are hardly perceptible in these early stages. In this work, we propose solutions for identifying domestic reindeer bones using 3D geometric morphometrics on isolated elements from the long bones of the forelimb (i.e. humerus, radio-ulna and metacarpal). These bones are important to understand both the feeding behaviour and the mobility of reindeer, and the potential effect of load-carrying or draught in the case of domestic reindeer. We analysed 123 modern specimens from Fennoscandia, including the two interbreeding subspecies currently present in these territories: mountain reindeer (Rangifer tarandus tarandus) and forest reindeer (R.t. fennicus); and where the sex and the lifestyle were known (i.e. free-ranging, racing or draught and captive individuals). A good level of discrimination between the size and shape variables of the bones of the forelimb was found among both subspecies and sexes. Moreover, individuals bred in captivity had smaller bone elements and a thinner and more slender morphology than free-ranging individuals. This demonstrates that the long bones of the forelimb can provide information on changes in feeding and locomotor behaviour prompted by the domestication process, like control and/or reduction of mobility and food of individual reindeer by humans. This also demonstrates that analysis in 3D geometric morphometrics is useful in detecting reindeer incipient domestication markers. Our results can be used by archaeologists to trace the early stages of domestication from fossil reindeer remains, and aid in reconstructing the socio-economic changes of past Arctic populations over time.

Landscape Approaches to Sustainability—Aspects of Conflict, Integration, and Synergy in National Public Land-Use Interests

Strong land-use pressure challenges sustainable development and calls for landscape approaches that balance economic, ecological, and socio-cultural aspects and interests. In the boreal, sub-alpine, and alpine regions in Sweden, encompassing 32 million ha, many and different land-use interests overlap, which causes risks for conflict, but potentially also suggests integration and synergy opportunities. Based on geographic information system (GIS) analyses of geographically delineated national interests regulated in the Swedish Environmental Code, including, amongst others, Natura 2000, contiguous mountains, recreation, reindeer husbandry, and wind power, and based on forestry as a dominating land use, we found extensive overlap among similar but also between dissimilar types of interest. In some mountain municipalities, our results show that the designated national interest area is four times as large as the available terrestrial area. Moreover, the overlap is much higher in the alpine than in the boreal biome, and there is increasing designation for nature conservation and a decreasing designation for national interests for culture, recreation, and tourism from south to north. We interpret the results with reference to multiple-use needs and opportunities for landscape approaches to sustainable planning. Departing from biodiversity conservation values, we also discuss opportunities to focus planning strategies on assessing synergy, integration, and conflict based on nature-based and place-based land-use characteristics.

Assessing the effectiveness of a national protected area network for carnivore conservation

Protected areas (PAs) are essential to prevent further biodiversity loss yet their effectiveness varies largely with governance and external threats. Although methodological advances have permitted assessments of PA effectiveness in mitigating deforestation, we still lack similar studies for the impact of PAs on wildlife populations. Here we use an innovative combination of matching methods and hurdle-mixed models with a large-scale and long-term dataset for Finland’s large carnivore species. We show that the national PA network does not support higher densities than non-protected habitat for 3 of the 4 species investigated. For some species, PA effects interact with region or time, i.e., wolverine densities decreased inside PAs over the study period and lynx densities increased inside eastern PAs. We support the application of matching methods in combination of additional analytical frameworks for deeper understanding of conservation impacts on wildlife populations. These methodological advances are crucial for preparing ambitious PA targets post-2020.

Assessing the effectiveness of protected areas for wildlife conservation is challenging. Here, Terraube et al. combine statistical matching and hurdle mixed-effects models to show that PAs have limited impact on population densities of large carnivores across Finland.

A review of climate change impacts on the ecosystem services in the Saami Homeland in Finland

The aim of this work is (i) to review the recent studies on weather and climate change in Finnish Sápmi and to present the literature review findings alongside our survey on the observations made by local reindeer herders on the same phenomena, and, further, (ii) to review the impacts of climate change on the ecosystem services (ES) in Finnish Sápmi. The focus of the study is on the impacts of climate change on those habitat, provisioning and cultural ecosystem services which are interconnected with the Saami way of life as Indigenous people and thus support the continuity of their culture. In the holistic world view of Arctic Indigenous peoples, material culture and non-material culture are not separated, and there is no boundary between nature and culture. However, cultural and spiritual meanings of ecosystems, species and landscapes are rarely taken into account in scientific research on ecosystems services. Our review indicates that mostly negative impacts of climate warming on ecosystems and traditional livelihoods are to be expected in Sápmi. The most profound negative impacts will be on palsa mire and fell ecosystems, in particular snowbeds, snow patches and mountain birch forests. Consequently, changes in ecosystems may erode cultural meanings, stories, memories and traditional knowledge attached to them and affect the nature-based traditional livelihoods. In a situation where our rapidly changing climate is affecting the foundations of the nature-based cultures, the present review can provide a knowledge base for developing adaptation actions and strategies for local communities and Indigenous peoples to cope with changes caused by climate change and other drivers.

A Hybrid Approach Using Fuzzy AHP-TOPSIS Assessing Environmental Conflicts in the Titan Mining Industry along Central Coast Vietnam

Environmental conflict management gains significance in rational use of natural resources, ecosystem preservation and environmental planning for mineral mines. In Central Coast Vietnam, titan mines are subject to conflicting use and management decisions. The paper deals with an empirical research on applying a combination of the fuzzy Analytic Hierarchy Process (AHP) and the fuzzy Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to measure environmental conflicts emerging as a result of titan mining in Vietnam. The methodology used in the paper combines the fuzzy AHP and the fuzzy TOPSIS to rank environmental conflicts and propose conflict prevention solutions in the titan mining industry of Ky Khang coastal commune (Ky Anh district, Central Coast Vietnam). Data was collected by using a questionnaire with 15 locals, 8 communal authorities, 2 district authorities, and 12 scientific experts on titan mining, environmental geology, and sustainability management. The result shows that, titan mining conflicts with the eight criteria of economic sectors at five alternative sites including beach, protected forest, agricultural area, settlement area, and industrial area. The conflicts between titan mining and forestry, agriculture, settlements, fishing and aquaculture are highly valued. The beach area shows most environmental conflict as a result of titan mining, followed by the agricultural area and settlement area. Based on the empirical findings, legal and procedural tools such as environmental impact assessments, strategic environmental assessments, integrated coastal zone management, marine spatial planning, and multi-planning integration advancing environmental management for titan mines in Vietnam are suggested.

Climate Change and Migration for Scandinavian Saami: A Review of Possible Impacts

Migration, especially of indigenous peoples, related to or influenced by climate change continues to gain increasing research and policy attention. Limited material remains for this topic for Scandinavia’s indigenous people, the Saami. This paper contributes to filling this gap by providing a review for the Scandinavian Saami of the possible impacts of climate change on migration. Environmental influences, social influences, and a synthesis through livelihoods impacts, including for reindeer herding, is provided, followed by a discussion of Saami responses to climate change and migration mainly through a governance analysis. Overall, climate change’s impacts on the Saami do not necessarily entail abandoning their traditions, livelihoods, or homes. Instead, the most significant impact is likely to be migrants moving into the Arctic to pursue resource opportunities. Working collaboratively with the Saami, policies and practices are needed to ensure that indigenous interests are respected and that indigenous needs are met.

Evolutionary responses to a changing climate: Implications for reindeer population viability

If we want to understand how climate change affects long-lived organisms, we must know how individuals allocate resources between current reproduction and survival. This trade-off is affected by expected environmental conditions, but the extent to which density independent (DI) and density dependent (DD) processes interact in shaping individual life histories is less clear. Female reindeer (or caribou: Rangifer tarandus) are a monotocous large herbivore with a circumpolar distribution. Individuals that experience unpredictable and potentially harsh winters typically adopt risk averse strategies where they allocate more resources to building own body reserves during summer and less to reproduction. Such a strategy implies that the females do not reproduce or that they produce fewer or smaller offspring. A risk averse strategy thus results in females with large autumn body reserves, which is known to increase their survival probabilities if the coming winter is harsh. In contrast, females experiencing predictable winters may adopt a more risk prone strategy in which they allocate more resources to reproduction as they do not need as many resources to buffer potentially adverse winter conditions. This study uses a seasonal state-dependent model showing that DD and DI processes interact to affect the evolution of reproductive strategies and population dynamics for reindeer. The model was run across a wide range of different winter climatic scenarios: One set of simulations where the average and variability of the environment was manipulated and one set where the frequency of good and poor winters increased. Both reproductive allocation and population dynamics of reindeer were affected by a combination of DI and DD processes even though they were confounded (harsh climates resulted in lowered density). Individual strategies responded, in line with a risk sensitive reproductive allocation, to climatic conditions and in a similar fashion across the two climatic manipulations.

Chronic wasting disease (CWD) in cervids

In April and May of 2016, Norway confirmed two cases of chronic wasting disease (CWD) in a wild reindeer and a wild moose, respectively. In the light of this emerging issue, the European Commission requested EFSA to recommend surveillance activities and, if necessary, additional animal health risk-based measures to prevent the introduction of the disease and the spread into/within the EU, specifically Estonia, Finland, Iceland, Latvia, Lithuania, Norway, Poland and Sweden, and considering seven wild, semidomesticated and farmed cervid species (Eurasian tundra reindeer, Finnish (Eurasian) forest reindeer, moose, roe deer, white-tailed deer, red deer and fallow deer). It was also asked to assess any new evidence on possible public health risks related to CWD. A 3-year surveillance system is proposed, differing for farmed and wild or semidomesticated cervids, with a two-stage sampling programme at the farm/geographically based population unit level (random sampling) and individual level (convenience sampling targeting high-risk animals). The current derogations of Commission Implementing Decision (EU) 2016/1918 present a risk of introduction of CWD into the EU. Measures to prevent the spread of CWD within the EU are dependent upon the assumption that the disease is already present; this is currently unknown. The measures listed are intended to contain (limit the geographic extent of a focus) and/or to control (actively stabilise/reduce infection rates in an affected herd or population) the disease where it occurs. With regard to the zoonotic potential, the human species barrier for CWD prions does not appear to be absolute. These prions are present in the skeletal muscle and other edible tissues, so humans may consume infected material in enzootic areas. Epidemiological investigations carried out to date make no association between the occurrence of sporadic Creutzfeldt-Jakob disease in humans and exposure to CWD prions.

European bison as a refugee species? Evidence from isotopic data on Early Holocene bison and other large herbivores in northern Europe

According to the refugee species concept, increasing replacement of open steppe by forest cover after the last glacial period and human pressure had together forced European bison (Bison bonasus)--the largest extant terrestrial mammal of Europe--into forests as a refuge habitat. The consequent decreased fitness and population density led to the gradual extinction of the species. Understanding the pre-refugee ecology of the species may help its conservation management and ensure its long time survival. In view of this, we investigated the abundance of stable isotopes (δ13C and δ15N) in radiocarbon dated skeletal remains of European bison and other large herbivores--aurochs (Bos primigenius), moose (Alces alces), and reindeer (Rangifer tarandus)--from the Early Holocene of northern Europe to reconstruct their dietary habits and pattern of habitat use in conditions of low human influence. Carbon and nitrogen isotopic compositions in collagen of the ungulate species in northern central Europe during the Early Holocene showed significant differences in the habitat use and the diet of these herbivores. The values of the δ13C and δ15N isotopes reflected the use of open habitats by bison, with their diet intermediate between that of aurochs (grazer) and of moose (browser). Our results show that, despite the partial overlap in carbon and nitrogen isotopic values of some species, Early Holocene large ungulates avoided competition by selection of different habitats or different food sources within similar environments. Although Early Holocene bison and Late Pleistocene steppe bison utilized open habitats, their diets were significantly different, as reflected by their δ15N values. Additional isotopic analyses show that modern populations of European bison utilize much more forested habitats than Early Holocene bison, which supports the refugee status of the species.

High female mortality resulting in herd collapse in free-ranging domesticated reindeer (Rangifer tarandus tarandus) in Sweden

Reindeer herding in Sweden is a form of pastoralism practised by the indigenous Sámi population. The economy is mainly based on meat production. Herd size is generally regulated by harvest in order not to overuse grazing ranges and keep a productive herd. Nonetheless, herd growth and room for harvest is currently small in many areas. Negative herd growth and low harvest rate were observed in one of two herds in a reindeer herding community in Central Sweden. The herds (A and B) used the same ranges from April until the autumn gathering in October–December, but were separated on different ranges over winter. Analyses of capture-recapture for 723 adult female reindeer over five years (2007–2012) revealed high annual losses (7.1% and 18.4%, for herd A and B respectively). A continuing decline in the total reindeer number in herd B demonstrated an inability to maintain the herd size in spite of a very small harvest. An estimated breakpoint for when herd size cannot be kept stable confirmed that the observed female mortality rate in herd B represented a state of herd collapse. Lower calving success in herd B compared to A indicated differences in winter foraging conditions. However, we found only minor differences in animal body condition between the herds in autumn. We found no evidence that a lower autumn body mass generally increased the risk for a female of dying from one autumn to the next. We conclude that the prime driver of the on-going collapse of herd B is not high animal density or poor body condition. Accidents or disease seem unlikely as major causes of mortality. Predation, primarily by lynx and wolverine, appears to be the most plausible reason for the high female mortality and state of collapse in the studied reindeer herding community.

Community-based management: under what conditions do Sámi pastoralists manage pastures sustainably?

Community-based management (CBM) has been implemented in socio-ecological systems (SES) worldwide. CBM has also been the prevailing policy in Sámi pastoral SES in Norway, but the outcomes tend to vary extensively among resource groups (“siidas”). We asked why do some siidas self-organize to manage common pool resources sustainably and others do not? To answer this question we used a mixed methods approach. First, in the statistical analyses we analyzed the relationship between sustainability indicators and structural variables. We found that small winter pastures that are shared by few siidas were managed more sustainably than larger pastures. Seasonal siida stability, i.e., a low turnover of pastoralists working together throughout the year, and equality among herders, also contributed to more sustainable outcomes. Second, interviews were conducted in the five largest pastures to explain the relationships between the structural variables and sustainability. The pastoralists expressed a high level of agreement with respect to sustainable policies, but reported a low level of trust and cooperation among the siidas. The pastoralists requested siida tenures or clear rules and sanctioning mechanisms by an impartial authority rather than flexible organization or more autonomy for the siidas. The lack of nestedness in self-organization for managing pastures on larger scales, combined with the past economic policies, could explain why CBM is less sustainable on the largest winter pastures. We conclude that the scale mis-match between self-organization and the formal governance is a key condition for sustainability.