Jon Moen

Higher levels of multiple ecosystem services are found in forests with more tree species

Forests are of major importance to human society, contributing several crucial ecosystem services. Biodiversity is suggested to positively influence multiple services but evidence from natural systems at scales relevant to management is scarce. Here, across a scale of 400,000 km2, we report that tree species richness in production forests shows positive to positively hump-shaped relationships with multiple ecosystem services. These include production of tree biomass, soil carbon storage, berry production and game production potential. For example, biomass production was approximately 50% greater with five than with one tree species. In addition, we show positive relationships between tree species richness and proxies for other biodiversity components. Importantly, no single tree species was able to promote all services, and some services were negatively correlated to each other. Management of production forests will therefore benefit from considering multiple tree species to sustain the full range of benefits that the society obtains from forests.

Effects of altitude and topography on species richness of vascular plants, bryophytes and lichens in alpine communities

Abstract Question: What is the relationship between species richness of vascular plants, bryophytes and macrolichens, and two important gradients in the alpine environment, altitude and local topography? Location: Northernmost Fennoscandia, 250–1525 m a.s.l. corresponding to the range between timberline and mountain top. Methods: The vegetation was sampled in six mountain areas. For each 25 vertical metres, the local topographic gradient from wind-blown ridge to snowbed was sampled in quadrats of 0.8 m × 0.8 m. Patterns in species richness were explored using Poisson regression (Generalized Linear Models). Functional groups of species, i.e. evergreen and deciduous dwarf-shrubs, forbs, graminoids, mosses, hepatics and lichens were investigated separately. Results: Functional groups showed markedly different patterns with respect to both altitude and topography. Species richness of all vascular plants showed a unimodal relationship with altitude. The same was true for graminoids, forbs and lichens analysed separately, but forb richness peaked at much higher altitudes than total richness. The richness of dwarf-shrubs decreased monotonically with altitude, whereas richness of mosses and liverworts showed an increasing trend. Significant interactions between altitude and local topography were present for several groups. The unimodal pattern for total plant species richness was interpreted in terms of local productivity, physical disturbance, trophic interactions, and in terms of species pool effects. Conclusions: Patterns in local species richness result from the action of two opposing forces: declining species pool and decreasing intensity of competition with altitude. Nomenclature: Nilsson (1986) and Hallingbäck (1995, 1996) for vascular plants, lichens and bryophytes, respectively.

Effects of Climate Change on Alpine Skiing in Sweden

Climate change has already affected and will continue to affect physical and biological systems in many parts of the world. For example, annual snow cover extent in the northern hemisphere has decreased by about 10% since 1966, and in Sweden, the last decade was wetter and warmer than the preceding 30-year period. These changes will affect many aspects of utilisation patterns that are dependent on the physical environment, such as alpine winter tourism. In this paper, we discuss the future development of the downhill skiing industry in Sweden. We first review trends in alpine winter tourism in relation to climate change together with regional projections of climate change. Secondly, we examine trends in climate parameters relevant to alpine winter tourism in Sweden during the last 30 years. Thirdly, we take these parameters, together with regional projections of climate change, and predict effects on the number of skiing days in order to estimate the monetary loss for the skiing industry in Sweden. The analyses show predicted losses that are larger than current ski-ticket sales. Adaptation strategies such as the development of year-round tourist activities should be developed as soon as possible.

Potential Effects of Climate Change on Treeline Position in the Swedish Mountains

Climate change may strongly influence species distribution and, thus, the structure and function of ecosystems. This paper describes simulated changes in the position of the upper treeline in the Swedish mountains in response to predicted climate change. Data on predicted summer temperature changes, the current position of the treeline, and a digital elevation model were used to predict the position of the treeline over a 100-year timeframe. The results show the treeline advancing upward by 233-667 m, depending on the climate scenario used and location within the mountain chain. Such changes hypothetically caused a 75-85% reduction in treeless alpine heaths, with 60-93% of the remaining areas being scree slopes and boulder fields. For this change to occur, the migration rate of the trees would be in the order of 23-221 m yr -1 , which is well within published migration rates for wind-dispersed deciduous trees. The remaining alpine areas would be strongly fragmented. These drastic changes would influence all aspects of mountain ecosystems, including biodiversity conservation and human land-use patterns.

Reindeer in the Swedish Mountains: An Assessment of Grazing Impacts

Abstract During the last decade, several well-publicized grazing-related incidents of vegetation degradation have helped to form an official opinion of overutilization of some mountain areas and a concern that Swedish reindeer husbandry may not be ecologically sustainable. We examine these examples in a temporal and management perspective to assess the scale of impact on summer grazing grounds in the Swedish mountains. Long-term data on population dynamics of reindeer show no trend with fluctuations around 225 000 animals for the last century. Data on grazing effects from Långfjället (Dalarna) and Mittåkläppen (Härjedalen) are discussed in detail. We compare these data to the situation in Finnmark, Norway, and in northern Finland where reindeer husbandry in recent decades does not seem to have been ecologically sustainable. We conclude that large-scale overexploitation by reindeer in the Swedish mountains is not evident. However, strong grazing and trampling effects may be found around enclosures and fences.

Long-Term Exclusion of Folivorous Mammals in Two Arctic-Alpine Plant Communities: A Test of the Hypothesis of Exploitation Ecosystems

During 1987-1994 we monitored changes in vegetation in exposures and permanent open plots established in two contrasting habitats: a productive hemiarctie tall herb meadow and a less productive alpine snow-bed. In addition. we studied the survival and growth of transplanted tall herbs. woody plants and arctie-alpine plants together with their seed germination and seedling survival in the same habitats. The primary objective of the study was to test the following prediction of the hypothesis of exploitation ecosystems: exclusion of herbivorous vertebrates from the snow-bed initiates radical changes in the vegetation of the snow-bed, whereas in the tall herb meadow, the impact of grazer exclusion on the vegetation is modest. The vegetation within the snow-bed exclosures changed from a grassland to a herbfield during the experimental period. Transplanted tall herbs and seedlings of erect woody plants had high rates of survival and growth in snow-bed exclosures. No such changes were seen in the open snow-bed plots. Survival rates of transplanted woody plans and tall herbs in open snow-bed plots were low and the net growth rates of the survivors were close to zero, In the productive tall herb meadow, vegetational changes were modest on open plots and within exclosures. No clear treatment effects on survival or growth of transplanted woody plants and tall herbs were observed. The results of the experiment thus conformed to the predictions of the hypothesis of exploitation ccosystems.

Species-specific plant responses to exclusion of grazers in three Fennoscandian tundra habitats

AbstractAn exclosure experiment performed in 1977-1985 in three tundra habitats was re-analyzed to examine species-specific plant responses for dominating species. In the lichen heath, four woody species showed the strongest increases as a response to the grazer exclosure. In the meadow, a tall grass showed the strongest increase in the exclosures, while a creeping woody plant increased in the snowbed exclosures. The species that increased in the exclosures were consistently those which were capable of elevating their foliage above the prevailing foliage height, while semiprostrate and prostrate plants (most notably bryophytes and lichens) suffered heavily from the exclusion of grazers.

On the balance between positive and negative plant interactions in harsh environments

Positive interactions between plants typically occur where the presence of a species ameliorates the abiotic environment for another. However, there is also a potential for resource competition to act at the same time, which creates a situation where the net outcome is a balance between positive and negative interactions. We present data from a nine-year study in two extreme high alpine habitats that was designed to test whether the effects of established Ranunculus glacialis individuals on germination and growth of Oxyria, digyna are primarily positive or negative at the altitudinal limit of vascular plants. We show net effects ranging from neutral to negative, but no positive effects were detected. We also argue that close associations between plants in these harsh environments may both ameliorate and deteriorate the abiotic environment, and that experimental manipulations are necessary to tell the difference.

Predicting lichen hydration using biophysical models.

Two models for predicting the hydration status of lichens were developed as a first step towards a mechanistic lichen productivity model. A biophysical model included the water potential of the air, derived from measurements of air temperature, relative humidity and species-specific rate constants for desiccation and rehydration. A reduced physical model, included only environmental parameters, assuming instantaneous equilibration between the lichen and the air. These models were developed using field and laboratory data for three green algal lichens: the foliose epiphytic Platismatia glauca (L.) W. Culb., the fruticose epiphytic Alectoria sarmentosa (Ach.) Ach. and the fruticose, terricolous and mat-forming Cladina rangiferina (L.) Weber ex Wigg. The models were compared and validated for the same three species using data from a habitat with a different microclimate. Both models predicted the length and timing of lichen hydration periods, with those for A. sarmentosa and P. glauca being highly accurate—nearly 100% of the total wet time was predicted by both the biophysical and physical models. These models also predicted an accurate timing of the total realized wet time for A. sarmentosa and P. glauca when the lichens were wet. The model accuracy was lower for C. rangiferina compared to the epiphytes, both for the total realized wet time and for the accuracy of the timing for the hydration period. These results demonstrate that the stochastic and continually varying hydration status of lichens can be simulated from biophysical data. Further development of these models to also include water-related activity, light and temperature conditions during the hydration events will then be a potent tool to assess potential lichen productivity in landscapes and habitats of various microclimatic conditions.

Improper excess light energy dissipation in Arabidopsis results in a metabolic reprogramming

BackgroundPlant performance is affected by the level of expression of PsbS, a key photoprotective protein involved in the process of feedback de-excitation (FDE), or the qE component of non-photochemical quenching, NPQ.ResultsIn studies presented here, under constant laboratory conditions the metabolite profiles of leaves of wild-type Arabidopsis thaliana and plants lacking or overexpressing PsbS were very similar, but under natural conditions their differences in levels of PsbS expression were associated with major changes in metabolite profiles. Some carbohydrates and amino acids differed ten-fold in abundance between PsbS-lacking mutants and over-expressers, with wild-type plants having intermediate amounts, showing that a metabolic shift had occurred. The transcriptomes of the genotypes also varied under field conditions, and the genes induced in plants lacking PsbS were similar to those reportedly induced in plants exposed to ozone stress or treated with methyl jasmonate (MeJA). Genes involved in the biosynthesis of JA were up-regulated, and enzymes involved in this pathway accumulated. JA levels in the undamaged leaves of field-grown plants did not differ between wild-type and PsbS-lacking mutants, but they were higher in the mutants when they were exposed to herbivory.ConclusionThese findings suggest that lack of FDE results in increased photooxidative stress in the chloroplasts of Arabidopsis plants grown in the field, which elicits a response at the transcriptome level, causing a redirection of metabolism from growth towards defence that resembles a MeJA/JA response.