Hilde Karine Wam

Moose summer and winter diets along a large scale gradient of forage availability in southern Norway

Studies on dietary functional responses in large herbivores are traditionally conducted by following individual animals. The method is very time-consuming, and hence, typically provides only a narrow array of forage species compositions. Here we use a range level approach to look at moose (Alces alces) selectivity for and utilization of forage species in relation to availability in both summer and winter. We compare 12 Norwegian ranges representing a large scale gradient in plant communities. The most important forage species in the diet were birches (Betula spp., comprising 43% of all trees browsed in summer and 27% in winter), rowan (Sorbus aucuparia, 25% of trees browsed in summer, 37% in winter), and bilberry (Vaccinum myrtillus, 42% of herbaceous epidermal fragments in summer feces). Selectivity for birches was positively related to its availability and negatively related to availability of rowan, Salix spp., and aspen (Populus tremula) together (all more selected for than birches). Multiple regression models including availability of several forage species were thus superior to single-species models in explaining the diet content of main forage plants. Selectivity for birches was also stronger in summer than in winter, while the opposite pattern was found for rowan. The finding is relevant for our evaluation of the quality of summer and winter ranges, and hence, their relative influence on population productivity. Our study underlines the need to incorporate species composition of available forage when quantifying dietary functional responses in selective herbivores such as moose. Furthermore, care should be taken when extrapolating data on moose diet across ranges or seasons.

Differential forage use makes carrying capacity equivocal on ranges of Scandinavian moose (Alces alces)

Availability of preferred forage is hypothesized to be positively related to demographic performance in selective ungulates. Comparing two regions with high density of moose (Alces alces (L., 1758)) having contrasting demographic performance and different composition of available plant species, we show that such a positive relationship may not always apply. The high-performance region (HP) had an estimated 41% higher total availability of browse per capita than the low-performance region (LP), but the availability of preferred species did not differ between the two regions. Although birch (genus Betula L.) was the most abundant browse in both regions (comprising 66% and 50% of the shoot amount available per m2 in HP and LP, respectively), it dominated the diet of moose only in HP (constituting, e.g., 69% of all trees browsed in summer compared with 22% in LP). Further research is needed to identify the cause of the seemingly suboptimal use of birch in LP. We also quantified factors that determine forage a...

Grouse Hunting Regulations and Hunter Typologies in Norway

Sustainable game management relies on satisfied hunters. Satisfaction determinants are seldom uniform across all hunters and may therefore be difficult to accommodate. Latent class analysis (LCA) is a probabilistic model-based approach to categorizing hunter typologies (by, e.g., their attitudes and preferences). We applied LCA to large-scale survey data relating to grouse hunting regulations in Norway (3,293 respondents). We identified three typologies with regard to importance of bag size (“The Experience Seeker” 43%, “The Bag Oriented” 32% and “The Northern Traditionalist” 25%) and crowding tolerance (“The Semi-tolerant Mainstream” 85%, “The Laissez Faire” 11%, and “The Passionate Crowd-avoiding” 4%). We could not find a single set of typologies that conformed to both aspects, which suggests that studies of this kind are more likely to be successful if target-specific. We conclude that knowledge of typologies is valuable for tailoring local hunting regulations, provided their actual distribution is identified at the appropriate scale.

Forest pasturing of livestock in Norway: effects on spruce regeneration

Forest pasturing of free-roaming livestock is a common practice in many parts of the world, but knowledge on how it affects tree regeneration in boreal forests is lacking. We mapped tree density, livestock site use and accumulated damage to young trees of commercial interest (Norway spruce, Picea abies L. Karst.) on 56 clearcuts inside and outside a fenced forest area used for livestock pasturing in Ringsaker, Norway. Inside the fence 56±1.8% of spruce trees were damaged compared to 37±3.4% outside. Proportion of damaged spruce trees was positively related to cattle use of the clearcut, but not so for sheep. On the most intensively used clearcuts, four out of five trees were damaged. The density of deciduous trees was five times lower inside compared to outside of the fence (varying with plant species). While livestock grazing may reduce resource competition in favour of spruce, the current animal density clearly is impeding forest regeneration in the study area.

Moose selecting for specific nutritional composition of birch places limits on food acceptability

Abstract Despite decades of intense research, it remains largely unsolved which nutritional factors underpin food selection by large herbivores in the wild. We measured nutritional composition of birch foliage (Betula pubescens) available to, and used by, moose (Alces alces) in natural settings in two neighboring regions with contrasting animal body mass. This readily available food source is a staple food item in the diet of moose in the high‐fitness region, but apparently underutilized by moose in the low‐fitness region. Available birch foliage in the two regions had similar concentrations of macronutrients (crude protein [CP], fiber fractions, and water‐soluble carbohydrates [WSC]), although a notably lower variation of WSC in the low‐fitness region. For minerals, there were several area differences: available birch foliage in the low‐fitness region had less Mg (depending on year) and P, but more Ca, Zn, Cu, and Mn. It also had higher concentrations of some plant secondary metabolites: chlorogenic acids, quercetins, and especially MeOH‐soluble condensed tannins. Despite the area differences in available foliage, we found the same nutritional composition of birch foliage used in the two regions. Compared to available birch foliage, moose consistently used birch foliage with more CP, more structural fiber (mainly hemicellulose), less WSC, higher concentrations of several minerals (Ca, Zn, K, Mn, Cu), and lower concentrations of some secondary metabolites (most importantly, MeOH‐soluble condensed tannins). Our study conceptually supports the nutrient‐balancing hypothesis for a large herbivore: within a given temporal frame, moose select for plant material that matches a specific nutritional composition. As our data illustrate, different moose populations may select for the same composition even when the nutritional composition available in a given food source varies between their living areas. Such fastidiousness limits the proportion of available food that is acceptable to the animal and has bearings on our understanding and application of the concept of carrying capacity.

Interactions between ungulates, forests, and supplementary feeding: the role of nutritional balancing in determining outcomes

People provide wild ungulates with large quantities of supplementary feed to improve their health and survival and reduce forest damage. Whereas supplementary feeding can positively affect the winter survival of ungulates and short-term hunting success, some of the feeds provided may actually reduce ungulate health and increase forest damage. Here, we highlight how recent advances in ungulate nutritional ecology can help explain why supplementary feeding can lead to undesirable outcomes. Using Europe’s largest cervid, the moose (Alces alces), as a model species, and Sweden, as the socio-ecological context, we explain the concept of nutritional balancing and its relevance to supplementary feeding. Nutritional balancing refers to how animals alter their food intake to achieve a specific nutritional target balance in their diet, by selecting balanced food items or by combining items with nutritional compositions that are complimentary. As the most common supplementary feeds used contain higher concentrations of non-structural carbohydrates than the ungulates’ normal winter diet, the consumption of such feeds may cause animals to increase their intake of woody browse, and thereby exacerbate forest damage. We also explain how animal health may be negatively affected by large intakes of such feed if complementary browse items are not available. We therefore suggest that the use of inappropriate feed is an additional means by which supplementary feeding may result in negative outcomes for hunters, forest owners, and wild animals.

Contrasting impact of whole-tree-harvesting on chemical quality of plant foliage in coastal versus inland forest

ABSTRACT Whole-tree-harvesting (WTH) is gaining support as a means to obtain more bioenergy from forests. One aspect that is scarcely addressed is its impact on the chemical quality of post-harvest plant growth, which may initiate ecological cascade effects through, for example, altered patterns of herbivory and decomposition. We measured C:N ratios and phenolic compounds in foliage from birch Betula spp. that had grown naturally after WTH and conventional harvest (CH) on two boreal sites in inland and more coastal Norway, three or five years after harvest. We found that carbon concentrations were higher after WTH compared to CH on the near-coastal site in spring and summer, but not on the inland site. The only observed change in nitrogen concentration after WTH was that it was lower compared to CH on the near-coastal site in autumn. In line with these changes, the C:N ratio was higher with WTH throughout the season on the near-coastal site, ostensibly favouring production or accumulation of plant defence metabolites. Expectedly, we observed altered concentrations of several phenolic compounds with WTH, particularly at the near-coastal site. Further studies are needed to clarify patterns, but our data strongly suggest that sustainability assessments of WTH should not ignore impact on plant chemical quality, and its potential consequences for trophic interactions.

Wild boar rooting in a northern coniferous forest – minor silviculture impact

European wild boar (Sus scrofa) is expanding northwards beyond its preferred habitat of broadleaved forests. We studied wild boar habitat use in a northern coniferous forest, and noted whether their rooting damaged roots, thereby influencing timber quality and forest regeneration (n = 562 rootings). Overall, the animals selected older spruce (Picea abies L.) forest of higher soil fertility with sparse field vegetation for rooting. During winter, they rooted more in pine (Pinus sylvestris L.) forest on lower soil fertility, possibly because the lichen cover can easily be removed even on frozen ground. Average size and depth of rootings were 6 ± 0.6 m2 and 10 ± 0.2 cm, respectively. Rooting occurred on <1% of the area and caused negligible damage to roots of trees with commercial value. Because the wild boar mainly rooted in older forest, rootings will do little to improve germination of seeds by scarification of the top soil layer.

Correction to: Forest pasturing of livestock in Norway: effects on spruce regeneration

The article “Forest pasturing of livestock in Norway: effects on spruce regeneration” written by Olav Hjeljord, Trond Histøl and Hilde Karine Wam was originally published Online First without open access.

Correction to: Compositional Changes in Foliage Phenolics with Plant Age, a Natural Experiment in Boreal Forests

The article Compositional Changes in Foliage Phenolics with Plant Age, a Natural Experiment in Boreal Forests, written by Hilde Karine Wam, Caroline Stolter and Line Nybakken, was originally published electronically on the publisher’s internet portal (currently SpringerLink) on August 29, 2017 without open access.