Cascading effects of moose (<Emphasis Type="Italic">Alces alces</Emphasis>) management on birds

Large herbivores often have key functions in their ecosystems, and may affect ecosystem processes with cascading effects on other animals. The mechanisms often involve relocations of resources of various kinds, including reduction in resource availability following foraging and increase in resources from animal excreta. As large herbivore populations in Europe generally are intensely managed, management activities may interact with the activities of the herbivores themselves in the effect on other ecosystem components. We investigated the effects of moose (Alces alces) winter browsing, together with the effect of net nutrient input via supplementary winter feeding of moose on functional composition and species richness of birds in a boreal forest. Supplementary feeding stations for moose had a net zero effect on bird species richness and abundance, because negative effects of moose browsing were balanced by positive effects of nutrient input. Sites with a similar browsing intensity as at feeding stations but without nutrient input had lower abundance and species richness than feeding stations. Functional groups of bird species showed differing responses: birds nesting at or below browsing height were negatively affected by moose browsing, whereas species nesting above the browsing zone were positively affected by moose browsing. Insect-eating species responded negatively to moose browsing on birch but positively to nutrient input at feeding stations, whereas seed-eating species responded positively to birch browsing and negatively to feeding stations. This study showed that both high levels of cervid activity and human management interventions influence bird communities.     

Mineral diversity in wild plants: benefits and bane for moose

We studied the mineral nutrition ecology of moose, Alces alces , by a comprehensive examination of concentration levels of 18 elements in browsing plants, and in rumen and distal colon contents, respectively. The plants, in total 14 species, included deciduous and evergreen trees, shrubs, herbs, grasses and aquatic macrophytes. Our study was done in four sites in southern Norway and the plants were sampled in spring, summer, autumn and winter to document seasonal trends. The plants were generally characterized by low concentrations of major elements, very low phosphorus: calcium ratios, and the willow Salix aurita – a preferred browse – had high cadmium concentrations, up to 9 ppm (dry mass). Sodium concentrations in terrestrial plants were significantly under the dietary requirement, while levels were sufficient in aquatic plants, which, however, had high concentrations of toxic heavy metals. We suggest that the moose experience a nutritional dilemma as a strong physiological need for sodium results in an overintake of heavy metals. A selective intake of plants rich in heavy metals was corroborated by high heavy metal concentrations in rumen and distal colon. Over all, the plants were characterized by a marked mineral diversity due to element concentration levels that were highly variable between species and sites. Thus, there is a strong link between plant species diversity and mineral diversity, which has a pivotal role for herbivores. It is concluded that a diversity of plant species is a prerequisite for the mineral diversity that the moose needs to obtain essential minerals, not only in sufficient amounts, but also in physiologically balanced proportions.     

Contrasting responses of two passerine bird species to moose browsing

Large herbivores may modify the ecosystem in a way that affects habitat quality and resource availability for other fauna. The increase in wild ungulate abundance in many areas may therefore lead to ecosystem changes, affecting distribution and reproduction of other species. Moose (Alces alces) in Scandinavia is a good example of a herbivore that has recently increased in abundance and has the potential to affect the ecosystem. In this study, we investigated how different levels of moose winter activity around supplementary feeding stations for moose affect reproduction in two insectivorous passerines: great tits (Parus major) and pied flycatchers (Ficedula hypoleuca). The two bird species showed contrasting responses to high moose activity at feeding stations. Great tits avoided habitats with high moose activity, where fledging success and feeding frequency was lower than at low moose activity habitats. Flycatchers nested more often at high moose activity habitats where fledging weight and feeding frequency were higher than at low moose activity habitats. Filming of nest boxes with great tits showed an increase in adult Lepidoptera in the diet at supplementary feeding stations for moose, and a smaller size of caterpillar prey at intermediate moose activity. The results support the hypothesis that herbivores may affect insectivorous passerines through changed arthropod food availability.     

Choice of feeding sites by moose during summer, the influence of forest structure and plant phenology

We observed forage and habitat selection in radio-collared moose at feeding sites in southeast Norway. Use of older forest increased from spring to autumn. Birch Betula spp. and bilberry Vaccinium myrtillus accounted for c. 75% of the diet. Occurrence of important forage plants, height of browse, and difference in phenology between plant species all appeared to play a role in moose selection of feeding sites. Shading influences moose forage by delaying plant phenology and possibly through its effect on leaf content of water and secondary compounds. On single birch trees, feeding was concentrated to the top branches at midsummer; during spring and autumn more leaves from side branches were eaten. Greater discrimination as vegetation matured was also evident from the wider variety of forage species used at midsummer. Selection of feeding sites was not related to density of important browse species. We propose that variations in light/shade conditions may play a role in moose choice of feeding sites and that moose on summer range will benefit from a heterogeneous mixture of plantations and older forest stands.     

Impact of simulated moose densities on abundance and richness of vegetation,herbivorous and predatory arthropods along a productivity gradient

Large herbivores can affect vegetation structure and species composition as well as material and energy flows in the ecosystem through their selective feeding, defecation, urination and trampling. These changes have a large potential to indirectly affect other trophic levels, but the mechanisms are poorly known. We studied the impacts of moose Alces alces browsing along a gradient of site productivity by experimentally simulating four different moose densities. Here we show that moose can affect the richness and abundance of three trophic levels in Swedish boreal forests through complex direct and indirect impacts, but in qualitatively different ways depending on how the physical habitat or food resources of a trophic level are affected. Vegetation richness had a hump‐shaped (unimodal) response to increased moose density. Leaf litter production decreased when browsing increased, which in turn depressed the abundance of flying prey for spiders. Consequently, spider abundance and richness declined monotonically. The responses of spider richness to moose density were further conditioned by site productivity: the response was positive at productive and negative at unproductive sites. In contrast, herbivorous Hemiptera were not affected by moose, most likely because the abundance of their food plants was not affected. The highest simulated moose density had an impact on all variables responding to moose even after a few years of treatment and can be considered as overabundance. We also show that the impacts of low or moderate moose density can be positive to some of the organisms negatively affected by high density. The level of herbivore population density that leads to substantial community impacts also depends on site factors, such as productivity.     

Moose and vole browsing patterns in experimentally assembled pure and mixed forest stands

Plants growing in diverse communities are believed to exhibit associational resistance to herbivores, but this hypothesis has seldom been tested experimentally for vertebrate herbivores in forest ecosystems. We examined browsing patterns of the two principal mammalian herbivores of Finnish boreal forests, moose and voles, in young stands where tree species diversity and composition were experimentally manipulated. The stands were composed either of monocultures or different 2–5 species mixtures of Norway spruce, Scots pine, Siberian larch, silver birch, and black alder. Voles and moose showed contrasting responses to stand diversity and species composition. In accordance with the predictions of the associational resistance hypothesis, vole damage was higher in tree monocultures than in mixed stands, although stand diversity effects were statistically significant only at one of the three study areas. Voles also damaged more trees in coniferous than in deciduous stands. In contrast, moose browsing tended to increase with the number of tree species in a stand and with the presence of the preferred tree species, birch, in a mixture. The observed differences in vole and moose responses to stand diversity and species composition are likely to be due to different feeding specialisation, foraging patterns, and movement ability of these herbivores. Voles switched to trees only when the supply of a more preferred food (grasses and forbs) was depleted and restricted their feeding choice only to the most palatable tree species regardless of the number of tree species present per stand. In contrast, tree branches and foliage represented an important part of moose diet throughout the year; moose may be able to tolerate secondary plant metabolites of different tree species better than voles and may thus benefit from diet broadening when more tree species are available. Furthermore, the home range size and foraging ability of these two very differently sized herbivores may partly explain the observed differences in utilisation of different tree species. Finally, both moose and voles showed high spatial and temporal variation in their feeding; in particular, vole damage was more influenced by tree species diversity in areas and years with high vole densities. Thus, diversification of forest stands may have very different effects on mammalian browsing depending on the herbivores present, their densities, and the tree species used in reforestation.     

Factors influencing choice of balsam fir twigs from thinned and unthinned stands by moose

Summary Moose were observed to browse preferentially on balsam fir (Abies balsamea) trees in stands where the stem density had been mechanically reduced to about 2000 stems/ha from over 30,000 stems/ha. Twigs from trees in thinned and unthinned stands were analyzed to test the hypotheses that moose were choosing thinned stands to maximize intake of a nutrient, or avoiding plant secondary compounds deliterious to digestion. Analyses included: twig length, weight, diameter, acid detergent fiber, neutral detergent fiber, dry matter digestibility, macroelements, crude fat (resins), crude protein, ash, and volatile secondary metabolites. Significantly higher concentrations of crude protein, P, Ca, Na, and crude fats occurred in trees from thinned compared to unthinned stands. Twigs from thinned stands were more digestible, longer, heavier, and had a greater diameter than those from unthinned stands. Several secondary metabolites were found in highest concentration in thinned stands. We suggest that moose chose thinned stands over unthinned stands for feeding because of high protein levels and large twigs. Trees in unthinned stands had protein levels below reported maintenance levels required by moose. Secondary metabolite concentrations were opposite to the direction predicted and the data do not support plant defence hypotheses for the chemicals analyzed.     

The vegetation of Nyumba ya Mungu reservoir, Tanzania

A study was made of the aquatic macrophyte ecology of Nyumba ya Mungu; a nine year old man-made lake in northern Tanzania. The vegetation is described with the aid of percentage cover histograms and standing crop estimates. Concurrent physical, chemical and biological studies helped in ecological interpretations. Distinct vegetation communities were found in the deltaic swamps of the two major inflow rivers and it is concluded that this was due to water chemical differences. The water of the more alkaline River Kikuletwa appeared to influence the greater part of the perimeter swamps as the species composition largely coincided with that reported for higher pH, higher conductivity African lakes. Typha domingensis swamp was predominant and extensive, whilst Cyperus alopecuroides and Paspalidium geminatum were also common emergent species. Floating and submerged plants were relatively unimportant in the lake with respect to cover. The major zonations of species appeared to be a function of water depth, while chemistry seemed the main factor controlling vegetation pattern. In conclusion the significance of interrelationships between the macrophytes and other aquatic organisms is discussed.     

The impact of simulated moose densities on conifer aphids along a productivity gradient

Large herbivores have a significant impact on boreal forest ecosystems. The modification of resources through their feeding induces changes in trophic dynamics and affects the direction of interactions in a community. Moose Alces alces may decrease the available plant biomass for herbivorous insects on one of their main winter forage species in Fennoscandia, Scots pine Pinus sylvestris, and indirectly alter the abundance of invertebrates through exploitative competition. Moose browsing can also induce chemical, morphological, and phenological changes in plants, changing their nutritive value to insect herbivores such as aphids. Habitat productivity may further modify the responses of aphids to moose browsing. We studied the responses of the gray pine aphid Schizolachnus pineti to different moose densities, and their relations to habitat productivity by sampling pine branches and measuring the number of aphids on pine needles. The experimental setup consisted of 8 exclosures along a productivity gradient, where the feeding, defecation, and urination of 4 densities of moose had been simulated for 7 yr. We here show that high levels of simulated browsing decrease the amount of gray pine aphids in areas with high productivity. In areas with low productivity, however, simulated browsing had no such effect. Habitat productivity should therefore be considered as an important factor that may determine the strength of an areas buffering capacity to high moose densities. Low resource environments appear to be favourable to specialist conifer aphids on pines under high browsing pressure, but the performance of generalist insect herbivores might be lowered.     

Mineral licks as a sodium source for Isle Royale moose

Summary Natural mineral licks and their use by moose (Alces alces) on Isle Royale National Park, Michigan, were studied during 1982–85. The distribution of known licks suggested that they occurred in association with glacial debris, primarily in the western portions of the island. Moose utilized mineral springs extensively during the spring-summer period, and at least 5 licks were used year-round. During summer, a pronounced diel pattern of moose visitation was apparent, with peak use occurring between 0400–0800 h. Although daytime lick use declined by late June, morning and evening use continued to be relatively high throughout the study period. Peak lick use coincided with leaf-emergence in spring. Moose continued to utilize mineral licks despite the availability of ponds containing aquatic plants. Sodium appeared to be the element attracting moose to licks where they ingest copious amounts of water. Observed sodium ingestion rates (0.35 g/min) at licks indicate that licks provide a more concentrated source of sodium compared to aquatic plants (0.023 g/min). Based on the data presented, we reject the conclusions of earlier workers that aquatic plants constitute the only significant source of sodium for Isle Royale moose.     

Nutrient release from moose bioturbation in aquatic ecosystems

While the ecological importance of bioturbation is well recognized and the prevalence of aquatic foraging by terrestrial ungulates is increasingly appreciated, research linking how terrestrial ungulates function as disturbance mechanisms via bioturbation in freshwater systems is lacking. The purpose of this study was to quantify potential nutrient pulses released from benthic sediments into the water column when moose Alces alces feed on aquatic plants. We also determined if we could experimentally mimic the benthic disturbance and the expected nutrient pulse created when moose feed aquatically. When moose foraged aquatically, significant releases of both total and dissolved phosphorus (P) and nitrogen (N) resulted in the waters that were disturbed in foraging areas compared to adjacent undisturbed waters. Nutrient concentrations for total P and N ranged from 42.5 × and 2.7 × greater in disturbed than undisturbed, respectively. Dissolved P and N were 26.8 × and 1.5 × greater, respectively, in disturbed versus undisturbed waters. Our experimental mimic created increases of total and dissolved P and N that were equivalent to pulses created by moose. This indicates that it is possible to experimentally test by proxy the potential impact of moose bioturbation on other ecosystem processes. This study is the first quantification of moose foraging as a consumer mechanism that influences the release of limiting nutrients in aquatic systems, thereby emphasizing the potential cascading importance for nutrient uptake and productivity of plants and microbes.     

Small mammal responses to moose supplementary winter feeding

Supplementary feeding of wild large herbivores is a widespread practice in North America and Europe. The presence of feeding stations may have ecological consequences through changes to animal distributions, patterns of herbivory and a net nutrient input into the ecosystem. In Fennoscandia, supplementary feeding of moose in winter (Alces alces) is increasing. Although it has been shown to affect bird communities, its effects on small mammal communities were unknown. Here, we studied the effects of moose supplementary feeding stations on plants and on abundance, reproduction, and biomass of small mammals in years with low and high vole abundance. We sampled small mammals with snap traps and conducted surveys of the field layer vegetation, at varying distances from moose supplemental feeding stations. Due to the vegetation changes induced by feeding stations, abundance of common shrews (Sorex araneus) and Microtus voles were positively affected by long-term moose winter feeding, while bank voles (Myodes glareolus) were not affected. Moose feeding stations did not affect reproduction, individual body mass, or the total biomass of small mammals. Moose winter-feeding stations have impacts on nontarget species, providing islands of preferred grass and forb habitat for Microtus spp. and common shrews, allowing them to penetrate into a matrix of less preferred forest habitat.     

Multi-Scale Foraging Habitat Use and Interactions by Sympatric Cervids in Northeastern China

Abstract: Moose (Alces alces) and roe deer (Capreolus pygargus) are sympatric in the forest region of northeastern China. Using univariate analyses of feeding sign data, we found the 2 species were positively associated, but there were distinctions between their use of forage resources across landscape, patch, and microhabitat scales. We used resource selection function models to predict the influence of environmental covariates on moose and roe deer foraging; we detected covariate effects at the landscape and microhabitat scales but not at the patch scale. Forage resources used by the 2 species were similar, but moose used wetter areas and more low-visibility habitats than did roe deer, which strongly avoided areas with sparse vegetation. Both species were influenced by forage abundance and distribution at the microhabitat scale but exhibited differences in intensity of use of plant species and microhabitats. Moose used areas with deeper snow and avoided hiding cover; roe deer avoided areas with higher total basal areas of tree stems and preferred areas with high plant species richness. For moose, there was a trade-off in the use of concealment cover between the landscape and microhabitat scales. We detected avoidance by moose of roads where roe deer occurred. Roe deer exhibited more capacity for coping with human disturbance and interspecific interaction. In areas similar to our study area, road closures and suppression of roe deer near roads within 3–5 years postlogging may benefit moose. Furthermore, a mosaic of areas with different logging intervals may contribute to spatial separation of moose and roe deer and promote their coexistence.     

An ecological study of the macrophytic vegetation of the Doodhadhari Lake,Raipur, M. P., India 1. Distribution and seasonal change in aquatic plants

Summary The distribution of aquatic plants in Doodhadhari lake, Raipur, M.P., India was studied by establishing eight stations. Permanent belt transects were run from all these eight stations every month for a year to assess the seasonal change in vegetational composition. Each transect was taken from the shore to the maximum depth. A contour survey was made and the total area during different seasons were determined. The fluctuation of water level was marked almost every fortnight for a year. The percentage frequency and percentage cover of different species were found to exhibit significant changes during different seasons. Except a few submerged aquatic plant species which are perennial all other species appear and disappear as the seasons progress. The perennial species which are not much affected by the seasonal change are heavily eaten by cattles. The pattern of succession has been outlined after evaluating the changes.     

小兴凯湖的水生植被及其生态作用

本文论述了小兴凯湖水生植物的种类组成、植被类型、生物量及其在湖泊淤积和渔业中的作用。该湖属老年期湖泊,水生维管束植物共有25科56种,优势种为竹叶眼子菜、荇菜、芦、菰等。植被类型可划分为沉水植被、浮叶植被和挺水植被等三个亚型,包括12个主要植物群丛。全湖水生植物总生物量(湿重)为196380吨;以植物现存量计算,草食性鱼类的年生产力应为78.75吨。由于水生植物大量繁殖,为减缓湖泊的垫平作用,可适量放养草食性鱼类,控制住水生植物的过量繁殖;同时引种一些经济水生植物,压住水中杂草的生长。     

四川邛海湖湿地水生维管植物的现状调查

本研究对邛海湖湿地水生维管植物种类及分布状况进行了调查.结果表明,邛海湖湿地现有水生维管束植物77种,隶属于25科50属.其中,蕨类植物5种,隶属2科3属;被子植物72种,隶属23科47属.从植物生态类型和生活型方面来划分,邛海水生维管束植物可分为湖区水生维管植物、河口滩涂植物和湿生植物三种类型.它们主要分布在湖泊的北面、西面和南面.区系分析结果表明,邛海水生维管束植物共有7种分布类型,其中以世界性分布型植物种最多.邛海湿地自然着生的水生植物群落破坏严重,挺水植物以上群落基本消失,浮水植物和沉水植物分布区锐减,分布深度退缩,分布密度减小.针对邛海湿地水生维管束植物存在问题,笔者提出了相应的解决方法和建议.该研究为邛海湿地的恢复和重建提供了理论依据.     

Comparative Space Use and Habitat Selection of Moose Around Feeding Stations

ABSTRACT The practice of feeding cervids in winter, either as a supplement to enhance nutritional status or to divert animals away from roads, railways, or vulnerable habitats, is rising noticeably. Moose (Alces alces) densities in Scandinavia are currently at historically high levels, resulting in amplified damage to economically important young Scots pine (Pinus sylvestris) forest stands. Nevertheless, there is limited information as to how diversionary feeding affects herbivore space use and habitat selection. We followed 32 female moose marked with Global Positioning System collars to evaluate 1) if feeding stations serve as attraction points to the extent that habitat-selection patterns resemble those of central-place foragers (i.e., high usage and more uniform selection close to the attraction point), and 2) if moose using feeding sites select young pine stands less than those not using feeding sites. Moose that used diversionary forage concentrated their space use around feeding stations and selected habitats as predicted for a central-place forager with a decreasing probability of using areas away from feeding sites and a low degree of habitat selectivity close to feeding sites. However, moose that used feeding sites continued to select young pine stands to the same extent as moose that did not use feeding sites. Feeding sites were, therefore, not successful in diverting moose away from valuable natural browse, so we recommend wildlife managers establish feeding sites in sacrifice areas where moose browsing is permissible and, if possible, >1 km from young pine plantations.     

Selectivity by moose vs the spatial distribution of aspen: a natural experiment

Patch use theory predicts that herbivores perceive food as patches and spend more time in high quality patches, i.e. feeding sites providing a high net rate of intake of energy and/or limiting nutrients. The herbivores should accordingly not discriminate among food items in such high quality patches, and food items should thus be eaten in proportion to availability. In contrast, classical diet theory assumes food selection to take place at the level of individual plants, and predicts that the forager should concentrate on the most profitable item until availability drops below some critical threshold.
Here we address how the spatial distribution of European aspen Populus tremula , a highly preferred browse species, affects the selectivity by moose Alces alces at the patch and the tree level. The study was performed in a managed boreal forest landscape in coastal northern Sweden, where aspen occurs highly aggregated almost exclusively in discrete patches. We compared moose' selectivity for aspen and browsing intensity on aspen ramets and other browse species in aspen patches versus at randomly located sites.
Random sites and aspen stands were utilised equally by moose in terms of overall use of forage. There was no difference in total coverage of forage species and relative moose density. Selectivity for aspen was stronger at random sites than at aspen sites, and the browsing intensity on aspen was similar. We conclude that moose did not perceive aspen stands as discrete patches, and used aspen ramets more in accordance with diet theory. These findings agree with the idea that large generalist herbivores strive to maintain a mixed and balanced diet, causing rare species to be over-utilised (negative frequency-dependent food selection). By such selective feeding, moose may reinforce the aggregated distribution of aspen in the managed boreal forest landscape.     

The role of moose <Emphasis Type="Italic">Alces alces</Emphasis> L. in boreal forest – the effect on ground beetles (Coleoptera,Carabidae) abundance and diversity

The indirect effect of moose Alces alces browsing on ground beetle's abundance and diversity was investigated by pitfall trapping in a mixed coniferous forest in Vestfold County (59°19′ N, 9°50′ E, Norway), during the summer of 2002. Three areas with different browsing pressures, ranging from non- to medium- and heavily browsed were chosen and dry weight of bilberry Vaccinium myrtillus and humidity at ground level were measured in the three locations. As predicted, the gradient analyses showed that browsing by moose influenced the composition of carabid fauna, and that browsing intensity and humidity covaried with the most important gradient in carabid species composition found across the three locations. Species that live in light stands with rather dry soil, were more often captured in the browsed areas, whereas shade tolerant and hygrophilous species were more abundant in the non-browsed area. The carabid abundance increased significantly with increasing browsing pressure. According to our predictions, the diversity at trap level (α-diversity) was higher in the highly browsed area. Conversely, species turnover (β-diversity) decreased with browsing intensity. On the other hand, the rarefaction analysis showed that the regional species richness (γ-diversity) was considerably higher in the medium browsed area than in the heavily browsed one, which is consistent with the intermediate disturbance hypothesis. This study indicates that moose, by reducing the bilberry that constitutes the field layer in summer, affect carabid species composition and might be capable to reshape the whole ecosystem in our study area by a cascade effect.     

The influence of flood duration on the surface soil properties and grazing management of karst wetlands (turloughs) in Ireland

This study tested the hypothesis that lake augmentation with well water impacts the distribution and abundance of aquatic plants in lakes. Water chemistry was measured from 14 wells, 14 augmented lakes, and 14 lakes without augmentation. Nine in-lake aquatic macrophyte abundance and species distribution metrics were measured in all lakes. Net photosynthetic rate (NPR) of nine submersed species was also measured in well and lake water. Augmentation increased alkalinity in receiving lakes, but total phosphorus was significantly lower, which resulted in lower chlorophyll and greater Secchi depths. Although measured NPR was higher for all plants incubated in well water, only one (emergent species richness) in-lake aquatic macrophyte metric was different in lakes with and without augmentation. Lake augmentation significantly changed water chemistry of receiving waters, but effects on aquatic macrophytes were minimal, suggesting that other environmental factors are limiting the distribution and abundance of macrophytes in the study lakes. The lower phosphorus levels in augmented lakes were unexpected because phosphorus concentrations in well water were significantly greater than in lakes with or without augmentation. Precipitation of calcium phosphate likely accounts for the reduced phosphorus levels in augmented lakes.