Sauli Härkönen

Moose browsing in young Scots pine stands in relation to forest management

Abstract The effects of moose browsing in young Scots pine stands were studied in southern Finland during 1993–1994. The influence of moose on tree species composition starts during the early development of young plantations. A considerable proportion of small pine seedlings was damaged, and hence the future development of the stand was retarded. The average biomass consumption of pine was relatively low increasing slightly with the density of pine seedlings. Browsing of pine was common in the patches with high density of preferred and highly utilized deciduous tree species, aspen and rowan. As elucidated by means of exclosure studies, the availability of tree species preferred and highly utilized by moose, e.g. rowan, is likely to be reduced also by early silvicultural cleaning. Removing excess birches by cleaning appears to be needed even in high-density moose areas to regulate the competition between tree species, especially the birch/pine height ratio. At the present average moose density of 0.4–0.6 km−2 forest land, considerable depletion of highly palatable tree species occurs locally in high-density moose ranges. When optimizing the development of young stands, silvicultural treatment timing and browsing by moose should be taken into account. It is considered important when combining forest and wildlife management to identify the conditions under which damage, overconsumption and possible long-term effects on forest ecosystems take place.

Use of Pellet Group Counts in Determining Density and Habitat Use of Moose Alces alces in Finland

In Finland, monitoring of the moose Alces alces population has been based on moose sighting cards and on aerial or ground censuses. However, considerable criticism has been levelled at these techniques, and there is an increasing need for alternative census methods in monitoring and managing moose populations. In this study, pellet group counts were carried out to determine the density and habitat use of moose in a wintering area in central Finland. Pellet group counts were made using both strip and plot sampling procedures. Estimates of moose density depended significantly on the sampling procedures and on the parameters used. Moose density estimates based on plots were twice those based on strips. Different plot intervals in plot sampling gave similar results. Both sampling procedures gave similar results concerning the habitat use of moose. The highest pellet group densities were observed in young Scots pine Pinus sylvestris dominated thinning stands where winter food availability is considerably high. Because food is a limiting factor in winter, pellet group numbers should obviously well reflect moose habitat affinity, which can be classified in terms of forest stand characteristics. Pellet group counts could possibly be used to estimate population densities for moose management. However, it would appear that the plot method, which up to now is the widely used method, overestimates moose densities. Because of the great variation in the results, other possible sources of error in the parameters used should also be taken into account in order to improve the accuracy of the method to be applied.

New bedding site examination-based method to analyse deer ked (Lipoptena cervi) infection in cervids

Invasion of the deer ked (Lipoptena cervi), an ectoparasitic fly commonly found in cervids, has been rapid in Finland during the last four decades. As the distribution area of this species has expanded from the south towards the northern latitudes, the associated problems have become more evident. Various animals such as horses, cattle and especially reindeer have been reported to host this parasite. Moreover, in certain areas, the deer ked causes major inconveniences for humans potentially limiting recreational activities in forests. We wanted to study if deer ked parasitism and intensity of the infection in winter time could be detected by using visual examination of the snow on cervid bedding sites and by analysing biotic samples found from the bedding sites. Our results demonstrate that chronic deer ked infection causes reddish-brown snow discolouration (host tissue fluid and deer ked faeces) on the bedding sites to the extent that parasitism can be diagnosed. Hence, we suggest that deer ked infection prevalence and range expansion could be rapidly monitored using our new practical and reliable method. In the future, bedding site analyses will likely be useful in predicting and potentially preventing the negative effects of this ecologically and socio-economically important parasite.

Experiments on the ectoparasitic deer ked that often attacks humans; preferences for body parts, colour and temperature.

The deer ked (Lipoptena cervi) can fail in its host search. Host search fails when an individual deer ked irreversibly accepts a host unsuitable for its reproduction (e.g. a human) and drops its wings. In northern Europe, the main host of the deer ked is the moose (Alces alces). The deer ked is increasingly causing serious problems for humans (for example, causing deer ked dermatitis) and is considered a threat for the recreational use of forests. The adult deer ked flies in early and mid-autumn to search for a host. Our aims were: (i) to study whether there are ways to avoid deer ked attacks by wearing particular clothing, and (ii) to evaluate deer ked host choice. Using human targets, we explored the cues the deer ked uses for host selection. We studied which part of the host body deer keds target and if body colour and temperature affect their choice. In our experiments, deer keds landed more on dark and red clothing than on white clothing. Moreover, deer keds mostly attacked the upper body parts and preferred the back side of the body over the front side. Finally, deer keds preferred the warmest areas of the host.

Selective browsing of moose (alces alces) on birch (betula pendula) clones

The moose choice of birch clones was studied by offering nine clones of European white birch plantlets to free‐ranging moose in a field cafeteria experiment. Twig quality, especially the defensive chemical content, affected moose feeding preference. Moose took a bite of larger diameter but tended to consume less from clones with a high phenol content. Moose preferred clones with small current annual shoots and few resin droplets.

EFFECTS OF SILVICULTURAL CLEANING IN MIXED PINE-DECIDUOUS STANDS ON MOOSE DAMAGE TO SCOTS PINE (PINUS SYLVESTRIS)

Silvicultural cleaning is commonly carried out in young stands to control competition between conifers and deciduous tree species. However, it has been questioned whether this practice affects moose (Alces alces L.) browsing on Scots pine (Pinus sylvestris L.) with respect to damage at the stand level. In this study, moose winter browsing was examined in relation to food availability in 19 Scots pine stands divided into silviculturally cleaned and non‐cleaned blocks. Cleaning had a negative effect on moose foraging in terms of reduced density, biomass availability, and height of the deciduous tree species. The total biomass consumed by moose was significantly lower on the cleaned blocks than on the non‐cleaned ones. There were no differences between the treatments in the amounts of pine consumed and in moose damage to pines. The density or biomass available of different deciduous tree species did not explain the variation in moose browsing on pine. In conclusion, timing of silvicultural cleaning with refe...

Threat of An Invasive Parasitic Fly, the Deer Ked (Lipoptena cervi), to the Reindeer (Rangifer Tarandus Tarandus): Experimental Infection and Treatment

Range expansion of ectoparasites can cause parasites to attack new host species. In these cases it is important for the parasite to be able to adapt to the new environment and to reproduce on the host. For the host, it is crucial to hinder successfully the development of long-lasting parasitic relationship. The deer ked (Lipoptena cervi) is a novel ectoparasite for northern cervids. We investigated if the deer ked can use the reindeer (Rangifer tarandus) as a host and, if it can, whether antiparasitic treatment against this parasite would be available. Three groups of reindeer were monitored: two groups of 6 reindeer were infected with 300 flies per each individual; a control group comprised 6 animals. One of the infected groups was treated with subcutaneous ivermectin. At the end of the experiment the infestation rate of the infected animals was low. The reindeer in the non-treated group had both live and dead deer keds and also a single pupa while the ivermectin-treated reindeer had only dead deer keds. As some deer keds survived and reproduced, the deer ked can potentially use the reindeer as a host but antiparasitic treatment may be effective against this parasite.

Molecular detection of Bartonella spp. in deer ked pupae, adult keds and moose blood in Finland

The deer ked (Lipoptena cervi) is a haematophagous ectoparasite of cervids that harbours haemotrophic Bartonella. A prerequisite for the vector competence of the deer ked is the vertical transmission of the pathogen from the mother to its progeny and transstadial transmission from pupa to winged adult. We screened 1154 pupae and 59 pools of winged adult deer keds from different areas in Finland for Bartonella DNA using PCR. Altogether 13 pupa samples and one winged adult deer ked were positive for the presence of Bartonella DNA. The amplified sequences were closely related to either B. schoenbuchensis or B. bovis. The same lineages were identified in eight blood samples collected from free-ranging moose. This is the first demonstration of Bartonella spp. DNA in a winged adult deer ked and, thus, evidence for potential transstadial transmission of Bartonella spp. in the species.

Effect of cleaning methods in mixed pine–deciduous stands on moose damage to Scots pines in southern Finland

Abstract The effect of different cleaning treatments on moose (Alces alces L.) damage to Scots pines (Pinus sylvestris L.) was examined using a generalized linear mixed model (GLMM) with a binomial response (logit-link function). The treatments were the following: no cleaning, point-cleaning of broadleaves (mainly birch, Betula pendula Roth and B. pubescens Ehrh.) within a radius of 1 m from the pine, point-cleaning delayed 2 years, topping of competing broadleaves (main stem cut at a height of 1.3 m) and total cleaning of broadleaves. A randomized complete block design with three replicates was established in three planted pine stands (mean height of pines 1.5 m). Measurements taken four growing seasons later (mean height of pines 3.5 m) showed that all cleaning treatments reduced moose damage, although the difference was not significant (p=0.078) in the case of topping. The proportion of damaged pines was predicted as a function of the characteristics of pines and broadleaves in two untreated, planted pine stands with a height of 3 m. Within these untreated stands the number of damaged pines increased in plots with a higher number of broadleaves and taller broadleaves. In conclusion, the results show that on relatively fertile growing sites of pine cleaning treatments reduced moose damage on pine. It is recommended that cleaning is performed before broadleaved trees occur as overgrowth above pines.

Differential selection of North American and Scandinavian conifer browse by northwestern moose (Alces alces andersoni) in winter

Scandinavian moose (Alces alces) eat Scots pine (Pinus sylvestris) in winter. Although North American moose are known to eat conifers such as true firs (Abies spp.) in winter, substantial consumption of pine by moose in North America has not been documented. Here, we document short-term winter preferences of human-habituated northwestern moose (Alces alces andersoni) for branches of mature North American and European conifer species as determined by a cafeteria-style feeding trial. Moose selected for species such as Douglas fir (Pseudotsuga menziesii; from which they took the smallest bite diameters) while avoiding species such as lodgepole pine (Pinus contorta; from which they took the largest bites) and hybrid white spruce (Picea glauca × engelmanii). The amount of species-specific biomass consumed by moose was negatively correlated with bite diameters taken from branches of those species and did not appear to be significantly influenced by differences in twig morphology between species. Our trial suggests that northwestern moose readily consume conifers in winter and, from the species we tested, prefer Douglas fir. While no clear preference existed between Scots pine and lodgepole pine, moose avoided lodgepole pine, but not Scots pine, relative to Douglas fir. Our trial suggests that northwestern moose are more likely to feed on the branches of Douglas fir than pine, which may be of interest to foresters managing conifers within the North American range of moose, particularly where Scots pine are being considered for planting.