Successional trends 219 years after fire in an old Pinus sylvestris stand in northern Sweden

Abstract. We present results from repeated analyses (1962, 1993) of a permanent plot established in 1947, combined with retrospective stand age structure data, in an old Pinus sylvestris stand in Muddus National Park, northern Sweden. The study points towards a successional pathway governed by concurrent disturbance effects of climate variability, reindeer grazing and fire. This is intermediate to the two often advocated ideas on dynamics in boreal forests, that is, one of disturbance-related tree regeneration/mortality and one of continuous regeneration. When the plot was established in 1947 the tree layer (> 1.3 m) consisted of 300 individuals/ha of P. sylvestris and 62/ha of Betula pubescens. Subsequently the stand has become more dense and the species dominance has shifted. In 1993, 362 P. sylvestris and 62 Picea abies individuals were present per ha, while no Betula individuals were found. The number of dead trees increased from zero in 1947 to 200/ha (Pinus) in 1993. Pinus was also the most common species in the sapling layer (< 1.3 m) throughout the study period, though the number dropped from 8912/ha in 1947 to 51% in 1993. Dead saplings decreased from 2650/ha in 1947 to ca. 50% in 1962, and only 9% in 1993. Temporal variations in mortality and sapling mean height coincided with variations in snow depth, indicating a critical period in sapling development when saplings are exposed at the snow/atmosphere interface. The number of living Picea saplings increased slowly until 1993; no dead saplings were found. Most Pinus recruited shortly after the 1774-fire, and during the second half of the 1900s. The major part of the spruce regeneration took place during the later half of the 1900s. No successful Betula recruitment has occurred after the 1930s, and no live Betula were present in 1993, which might be explained as an effect of increased reindeer browsing – the reindeer stock has grown by 50% since 1961. Although subjected to high mortality, Pinus regenerated and maintained a seedling/sapling bank. In this way Pinus remained dominant in the tree layer after more than 200 post-fire years. The importance of the shade-tolerant Picea has slowly increased, while Betula has died off. Thus, even after 219 yr since fire there is an early successional trend in the stand. This suggests that an increased chronic disturbance (grazing/browsing by reindeer) has partly succeeded earlier discrete fire-disturbance events, and maintained a continuous seedbed favouring the shade-intolerant pine recruitment.     

Elaphostrongylus rangiferi: Influence of temperature,substrate, and larval age on the infection rate in the intermediate snail host, Aarianta arbustorum

The infection rate of the first stage larval nematodes, Elaphostrongylus rangiferi, was studied experimentally, using the juvenile snail Arianta arbustorum as intermediate host. The nematode showed a linear, fivefold increase in infection rate within the temperature range of 4 to 28 C. The snails were exposed to the larval nematodes on three different substrates. The highest infection rate was recorded when snails were exposed in tap water and significantly slower infection rates were obtained when either lettuce or soil was used as the substrate. First stage larvae of E. rangiferi were infective for at least 2 months when stored at 12 C. Throughout this period, the infection rate showed a significant decline, while the motility of the larvae remained unchanged.     

Reindeer Chukchi and Siberian Eskimos: Studies on blood groups,serum proteins,and red cell enzymes with regard to genetic heterogeneity

Phenotype and allelic frequencies for ABO, MNSs, P, Rh, Kell, Duffy, and Diego blood groups, as well as for transferrins (Tf), haptoglobins (Hp), phosphoglucomutase 1 (PGM₁), adenylate kinase (AK), 6-phosphogluconate dehydrogenase (PGD), and acid phosphatase (AcP) are described in 9–10 adjoining populations of Reindeer Chukchi. Additionally, one of three presently existing territorial subgroups of Siberian Eskimos was studied. The total sample size ranges from 931 to 1,066 in Chukchi, and from 99 to 102 in Eskimos, depending on the genetic system studied. Substantially reduced samples for Kidd and ABO secretion were investigated solely in the Reindeer Chukchi. Significant heterogeneity of allelic frequencies has been observed among Chukchi populations (χ = 378.47, P < 0.001). Summed genetic heterogeneity between Reindeer Chukchi and Siberian Eskimos was also found to be highly significant (χ = 186.54, P < 0.001). Both groups can be readily discriminated with only four outliers: NS , P¹, R¹, and P^a. Random genetic drift is suggested to be responsible for a large proportion of heterogeneity of allelic frequencies at the MNSs, P, and Rh blood-group system sites both among the Chukchi and Eskimos. Conversely, stabilizing selection is assumed as the principal agent maintaining homogeneous allelic frequencies at the AcP locus within the Chukchi subdivisions, whereas disruptive selection may be considered as a major factor leading to different p^a frequencies between Chukchi and Eskimos.     

Quand le renne entra au panthéon du Paléolithique supérieur ?

By means of critical analysis of style of reindeers figures calling on graphic detailed conventions and on their associations with a cattle into that species of very rigorous climate prevail over the others, such musk-beef, glutton and saïga, but also plenty of bison's, as well as horses, it appears hardly likely, to do not say impossible, that reindeers of Chauvet's cave can have aurignacian origin. That all the more as they would be all alone in this case among one hundred sixty-six taking the census of representation. Their comparison with the other reindeers of the different sites generally do not distinguish from solutrian or Magdalenian reindeers and bring together particularly with Gabillou by many stylistic concurrents. If A. Leroi-Gourhan has already established that link between horse and reindeer only appears at Magdalenian, it seems now that it is possible to extend to superior Solutrian in support of representations of our inventory, reflecting climate aggravation that takes place at this moment and promotes plenty of two species in the neighbourhood.     

Strontium isotope evidence for migration in late Pleistocene Rangifer: implications for Neanderthal hunting strategies at the Middle Palaeolithic site of Jonzac, France

In order to understand the behaviours and subsistence choices of Palaeolithic hunter-gatherers, it is essential to understand the behavioural ecology of their prey. Here, we present strontium isotope data from sequentially-sampled enamel from three reindeer (Rangifer tarandus ssp.) and a single bison (Bison cf. priscus) from the late Middle Palaeolithic site of Jonzac (Chez-Pinaud), France. The results are used to investigate the ranging and migratory behaviours of these important prey species. We found that the bison had isotope values most consistent with a local range, while the three reindeer had values indicating a seasonal migration pattern. Due to the similarity of the patterning of two of the three reindeer and in conjunction with zooarchaeological results, we suggest that they may have been from the same herd, were likely killed around the same point during their seasonal round and may therefore be the product of a single hunting event or a small number of successive hunting events. The isotope analyses complement the zooarchaeological data and have allowed greater insight into the palaeoecology of these species, the palaeoenvironment, and Neanderthal site use and hunting strategies.     

Does climate change influence the availability and quality of reindeer forage plants?

The northward and upward movement of the tree line and gradual replacement of lichens with vascular plants associated with increasing temperatures and nutrient availability may change the reindeer pastures in Northern Fennoscandia. The productivity of reindeer forage will most probably increase, but their protein (nitrogen) concentrations may decrease because of higher temperatures and CO₂ concentration. In the long term, the nutritive value of forage will depend on the mineralization rate and nutrient uptake from the soil. Enhanced UV-B is likely to increase the concentration of phenolics, decreasing forage quality and choice, but reindeer may adapt to increased phenolics. Increased winter precipitation, the occurrence of ice layers, deeper snow cover, and the appearance of molds beneath the snow cover may reduce the availability and/or quality of reindeer forage, but prolongation of snowless periods might have the opposite effect. The net balance of negative and positive effects will vary regionally depending on the climate, bedrock, vegetation, reindeer herding systems and socio-political factors. Multidisciplinary research is needed most importantly on the effects of the changing winter climate on reindeer forage, and the effect of modified forage quality on reindeer physiology.

Antlers and parasites

Development of ornamental characters exposed to directional selection may be particularly sensitive to the effect of parasitic infections. Antlers are ornamental characters of importance in intraspecific interactions, and are in reindeer (Rangifer) developed by both males and females. By antihelmintic treatment of naturally infected female reindeer we show that parasite intensities affect development of antler asymmetry, but not antler length. These results suggest that asymmetry in antlers may reflect parasite intensities and thus be of importance in intraspecific assessment of genetic resistance towards infectious organisms.     

Ecological role of reindeer summer browsing in the mountain birch (<Emphasis Type="Italic">Betula pubescens</Emphasis> ssp. <Emphasis Type="Italic">czerepanovii</Emphasis>) forests: effects on plant defense,litter decomposition,and soil nutrient cycling

Mammalian herbivores commonly alter the concentrations of secondary compounds in plants and, by this mechanism, have indirect effects on litter decomposition and soil carbon and nutrient cycling. In northernmost Fennoscandia, the subarctic mountain birch (Betula pubescens ssp. czerepanovii) forests are important pasture for the semidomestic reindeer (Rangifer tarandus). In the summer ranges, mountain birches are intensively browsed, whereas in the winter ranges, reindeer feed on ground lichens, and the mountain birches remain intact. We analyzed the effect of summer browsing on the concentrations of secondary substances, litter decomposition, and soil nutrient pools in areas that had been separated as summer or winter ranges for at least 20 years, and we predicted that summer browsing may reduce levels of secondary compounds in the mountain birch and, by this mechanism, have an indirect effect on the decomposition of mountain birch leaf litter and soil nutrient cycling. The effect of browsing on the concentration of secondary substances in the mountain birch leaves varied between different years and management districts, but in some cases, the concentration of condensed tannins was lower in the summer than in the winter ranges. In a reciprocal litter decomposition trial, both litter origin and emplacement significantly affected the litter decomposition rate. Decomposition rates were faster for the litter originating from and placed into the summer range. Soil inorganic nitrogen (N) concentrations were higher in the summer than in the winter ranges, which indicates that reindeer summer browsing may enhance the soil nutrient cycling. There was a tight inverse relationship between soil N and foliar tannin concentrations in the winter range but not in the summer range. This suggests that in these strongly nutrient-limited ecosystems, soil N availability regulates the patterns of resource allocation to condensed tannins in the absence but not in the presence of browsing.     

Variation in gestation length among captive reindeer (Rangifer tarandus tarandus)

An estimated 90% of reindeer females are mated in a 10- to 21-d interval and give birth in an equally synchronized manner. Reported gestation length in reindeer is highly variable (range, 203 to 240 d), almost twice the reindeer estrous cycle length. Previously, we identified a significant, negative relationship between gestation length and conception date in a small group of reindeer. In the current study, the negative relationship was investigated in a switchback design, where reindeer were divided into two groups synchronized for early and late mating over a 2-yr trial. Regression analysis of 11 paired observations produced a negative (P < 0.001) association between gestation length and conception date (slope = − 0.31). Dam weight at breeding and prior to parturition, calf birth weight, and calf sex were not significant variables in the regression. Regression analysis of a larger data set from two University of Alaska Fairbanks reindeer herds, where conception date (verified by systemic progesterone) and gestation length were recorded (historical data set), supported previous conclusions (n = 70; slope = −0.37; P < 0.001). Although the calf sex ratio did not differ with gestation length, there was a positive relationship (r² = 0.19; P = 0.014) between male birth weight and gestation length in the larger data set. The negative relationship between conception date and gestation length enhanced calving synchrony, though the limits of gestation plasticity and underlying mechanisms are not clear. The potential role of photoperiod on early embryonic development is discussed.