Roland Pape

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?

Reindeer grazing has been entitled as ecological keystone in arctic–alpine landscapes. In addition, reindeer husbandry is tightly connected to the identity of the indigenous Sámi people in northern Europe. Nowadays, reindeer husbandry is challenged in several ways, of which pasture degradation, climate change, conflicting land uses and predation are the most important. Research on reindeer-related topics has been conducted for more than half a century and this review illuminates whether or not research is capable to match these challenges. Despite its high quality, traditional reindeer-related research is functionally isolated within the various disciplines. The meshwork of ecology, socio-economy, culture and politics, however, in which reindeer husbandry is embedded by various interactions, will remain unclear and difficult to manage, if actors and relationships are kept separate. We propose some targets for new integrative research approaches that incorporate traditional knowledge and focus on the entire human-ecological system ‘reindeer husbandry’ to develop solutions for its challenges.

Alpine Soil Temperature Variability at Multiple Scales

Abstract The functioning of ecosystems is strongly correlated to soil temperature dynamics. Because only a few studies so far have investigated the spatio-temporal variability of alpine soil temperatures, we proceeded to analyze soil temperatures in a heterogeneous alpine landscape by means of a multi-scale approach. We combined vertical soil temperature gradients from surface to 15 cm depth, microspatial variability within small catchments, and altitudinal changes of a continental mountain system. We analyzed differences at single sites and at multiple spatial scales. We found that microtopographic site conditions dominated thermal changes along altitudinal gradients. The adiabatic lapse rate did not show high correlations with local soil temperature gradients. We used isopleth diagrams of soil temperature gradients and corresponding scatterplots of soil temperature gradients between each pair of sites and low alpine–middle alpine mountain couples to quantify these overlying phenomena. This enabled us to quantify the significance of soil temperature gradients across vertical soil profiles, topography, and altitude in order to facilitate future microclimate extrapolation and modeling in high mountain (alpine) landscapes. Such procedures are crucial for describing expected responses of alpine ecosystems to global climatic change.

Diversity Patterns in Relation to the Environment in Alpine Tundra Ecosystems of Northern Norway

ABSTRACT We analyzed diversity patterns of alpine tundra ecosystems along environmental gradients. We hypothesized that alpine diversity is affected by climate at local and regional scales, nutrient availability, soil moisture, and disturbance related to herbivory. In all, 232 samples in 11 study areas in Troms and Finnmark counties were analyzed with regard to α- and β-diversity of vascular plants and lichens. Relationships between α-diversity and environmental variables were analyzed by regression trees. β-diversity defined as species turnover was investigated using indirect ordination methods. Sites with non-acidic soil parent material showed highest species densities. Lowest species numbers were typical for extreme topographic positions. Heavily grazed samples showed less species numbers and coverage percentage of vegetation. The number of graminoid species was found to be highest in areas of high grazing pressure. We concluded that α-diversity was controlled by growing season, snow cover, pH, soil moisture, disturbance, temperature, and precipitation, stressing the importance of multi-factorial approaches in diversity studies. Determinants of β-diversity were predominantly local environmental conditions, whereas regional conditions were less important.

The alpine treeline under changing land use and changing climate: Approach and preliminary results from continental Norway

This study aims at improving the comprehension of the alpine treeline, partly as a means of projecting landscape evolution in an anticipated warmer future. The main problem to be solved is to distinguish effects and responses of climate change and human impact, two driving forces which have both caused an increase in the altitude of the alpine treeline over the past century. Thus, an interdisciplinary approach has been transposed to the Norwegian mountains, combining socio-geographical, landscape ecological and adjusted dendroecological methods. Preliminary results presented for the continental Norwegian mountain region Vågå, Oppland, prove the treeline to be in a regeneration stage after a period of major human forced depression. Climatic conditions at the treeline and growth rates of birches indicate that the treeline is not at its distribution limit. Consistent grazing pressure and dense vegetation cover is the most likely explanation.

Ecological dynamics in habitat selection of reindeer: an interplay of spatial scale, time, and individual animal's choice

While striving for “global” species models of habitat selection, spatiotemporal variation in utilization patterns within a particular habitat and intraspecies variation in space use are still poorly understood. We addressed these challenges by exploring habitat use of domesticated reindeer (Rangifer tarandus tarandus), focusing on factors that underlie ecological dynamics in habitat selection. We analyzed habitat selection of 15 (±2) female reindeer in southern Norway separately for (a) region and home range, (b) seasonality, and (c) each Global Positioning System (GPS)-collared reindeer. We explicitly evaluated spatiotemporal and intraspecies variability in habitat selection by applying multivariate ordination techniques based on the niche concept. In contrast to global assumptions, our results reveal a considerable and partly unpredictable amount of variation in habitat selection resulting from the interplay of spatial scale, time, and individual animal choice. Thus, we conclude that across-scale approaches describing animal space use facilitate better understanding of habitat selection instead of finding a single “best” model that indicates the strongest species–habitat relationships.

Seasonality of habitat selection shown to buffer alpine reindeer pastoralism against climate variability

Climate-driven variability of habitat selection of large herbivores has not yet been explicitly analyzed. To this end, we aimed to better understand the climate-ecological mechanisms behind geographic patterns of reindeer (Rangifer tarandus tarandus) habitat utilization. Our study area comprised of the ranges of Filefjell Reinlag, southern Norway (60°20′–61°20′ N; 8°20′–9°50′ E). We analyzed habitat selection of 20 (± 2) GPS-collared female reindeer over a period of five years. We examined the mechanistic forces of habitat selection variability by applying a novel stepwise factor analysis approach based on the niche concept. We characterized the governing conditions for inductively delineated seasons and extracted in a first step for each year the seasonal scores of the individual animals on the environmental variables to explain their habitat use. For each season, we then conducted principal component analyses (PCA) to analyze the inter-annual variability in habitat preferences using the individual scores for the environmental variables per year. In a third step, we fit our potential drivers as vectors onto each seasonal PCA and retained solely significant drivers. Our results reveal complex spatiotemporal patterns of habitat selection that are driven by seasonality, year-to-year climate variability, and the choice of individual animals. In contrast to expected similarities between conspecifics, our analyses revealed varying degrees of intra-species variability and therefore suggest that responses of individual reindeer to climate variability are inconsistent. Moreover, we found annually reoccurring patterns of habitat selection strength during different seasons that help explain coping capacities of reindeer against climate variability. In contrast with our expectations, we detected a very high inter-annual variability in habitat preferences to be related to governing climatic conditions. Here, we present new evidence for the variability of response mechanisms of reindeers habitat selection shown throughout different seasons and years that buffer alpine pastoralism against climate variability. Our work contributes to a better understanding of alpine ecological response mechanisms as a key for projections of future responses to climate change.

Alpine activity patterns of Mitopus morio (Fabricius, 1779) are induced by variations in temperature and humidity at different scales in central Norway

Our research addresses questions about how micro-climate affects activity abundance of a common and widespread harvestman in an alpine ecosystem. Activity patterns of the Harvestman Mitopus morio (Fabricius, 1779) were studied along different alpine gradients in the central Norwegian Scandes. Within a nested design, we surveyed 18 alpine habitats with pitfall traps and microclimatological equipment along oceanic-continental, two elevational, and (fine-scaled) microtopographic gradients. Sites in the oceanic region of the Scandes showed generally higher abundance of M. morio than sites in the continental region. Furthermore, along the elevational gradient, middle-alpine sites showed higher abundances than low-alpine sites. These general patterns are best explained by higher humidity in the oceanic region and in the middlealpine belt. Focusing at a finer scale, i.e. one elevational level within each region, revealed partly opposing activity patterns within relatively short distances. While in the western middle-alpine belt these patterns were best explained by humidityrelated measures but now with higher activity abundance during drier conditions, in the drier eastern middle-alpine belt heat sums rather than humidity were found to be the best explanatory variables for the observed patterns. Hence, our results imply a pronounced different reaction of the two populations towards climatic variables that partly even contradict the previously described general pattern. Regardless whether these differences in activity abundance in M. morio are a form of phenotypic plasticity or adaptation, our findings stress the importance of detailed autecological knowledge combined with fine-scaled climatic measurements when aiming at predictions about possible future ecosystem structures and spatiotemporal phenomena. M. morio proves to be an ideal biogeographic model organism for understanding spatio-temporal responses of alpine ecosystems under modified climatic conditions.

Determinants of arctic-alpine pasture resources: the need for a spatially and functionally fine-scaled perspective

ABSTRACT The current greening of arctic-alpine landscapes poses the question about its underlying ecological mechanisms. Given its importance across various contexts and scales, it is vital to understand the drivers of contemporary patterns in phytomass and primary productivity to improve predictions under altered environmental conditions. Here, we analysed local patterns in above-ground phytomass, calorific energy contents, and primary productivity as important pasture resources in a complex arctic-alpine landscape along pronounced micro-topographical and elevational gradients. Using data from 110 sampling sites, of which 38 were equipped with on-site recordings of soil moisture and near-surface temperatures, we asked how the observed patterns in pasture resources are related to the environment and whether commonly used structural proxies or physiologically relevant, functional data were better suited for their explanation. Using partial least squares regression based on a set of structural plus functional explanatory variables, the latter revealed to be the best determinants. Our results suggest how the ecological mechanisms behind contemporary pasture resources and, likewise, the arctic-alpine greening are interactively driven by the near-surface thermal regime, associated snow coverage, and soil moisture availability. Moreover, they reveal an obvious decoupling of near-surface processes from the overall atmospheric and topographic constraints which are commonly used as proxies. We conclude that estimates of current and future pasture resources would be significantly improved if fine-scaled, functional data, rather than structural data, could be used. However, this implies further effort in providing such data, since appropriate regionalization techniques are still lacking.

Towards a process-based biogeography of reindeer—scaling space, time, and organizational levels of space use

ABSTRACT Due to increasing anthropogenic habitat alteration, fragmentation, and loss, the analysis of how, when, and why animals select particular habitats has become a central issue in ecology and biogeography. Animals adapt to spatiotemporal variability in resources either by tracking these resources or by plasticity in behavior to cover their needs, leading to three important implications: movement, temporal variation, and individual trade-offs leading to intra-species variability, all of which are directly linked to the use of space by animals. Based on GPS-tracking of domesticated reindeer in southern Norway, the authors addressed these issues by analyzing movement patterns and space use simultaneously across different temporal and organizational scales. Emerging information about the space use by reindeer was found explicitly linked to scaling relations, reflecting the matter of scale as having important functional implications rather than solely being a technical question of extent and resolution. Adding movement into the analysis of space use further advances the necessary functional perspective on space use. The authors conclude that scaling not only space but also time and the organizational level, in combination with accounting for different behavioral states, brings biogeography closer to a process-based view, rather than solely pattern-based view.