Subalpine Habitats Research Articles

A new rare species of Acacia from north-east Victoria

A new, rare wattle, Acacia daviesii sp. nov., known from only 10 populations discovered in mountainous, subalpine habitat in north-eastern Victoria, is described and illustrated. A comparative morphological study was undertaken, based on phyllode characters measured from all 10 known populations and herbarium specimens of the five most similar Acacia species: A. acinacea, A. aspera, A. glandulicarpa, A. gunnii and A. paradoxa. The new species has a pendulous habit and resinous phyllodes covered by stalked multicellular glands. Acacia daviesii forms clones by root suckering and seed set appears to be rare. Isozyme analysis based on nine enzyme systems showed that plants within any single population are genetically identical. Variation was detected between all but two populations with only nine known genotypes in an area of 12 km2.

The adrenocortical responses to stress in breeding male Chaffinches Fringilla coelebs and Bramblings F. montifringilia in Sweden

There is growing evidence that birds, and possibly other vertebrates, modulate the adrenocortical response to acute stress as measured by increases in plasma levels of corticosterone following capture and handling. Field-endocrine investigations of these adrenocortical responses to capture stress have begun to indicate ecological bases for such endocrine phenomena. One hypothesis states that populations of birds breeding under extreme conditions such as in Arctic and subarctic habitats, where the breeding season also is short, should suppress the adrenocortical response to acute stress so as to allow onset of breeding under potentially severe conditions. To test this we measured increases in circulating levels of corticosterone following capture and handling in a population of male Chaffinches Fringilla coelebs breeding in southern Sweden. The dynamics of changes in corticosterone levels during this capture stress protocol were compared with those collected from male Brambling F. montifrigilla breeding in a subalpine habitat in northern Sweden where conditions are more severe and the breeding season short. Contrary to the predictions, male Bramblings showed a greater adrenocortical response to stress as indicated by the pattern of corticosterone levels in blood. Both male Bramblings and Chaffinches show marked individual variations in the pattern of corticosterone changes following capture. In Chaffinches the initial corticosterone were negatively correlated with body mass and body size expressed as ratio of body mass to wing length cubed. The percent increase in corticosterone and maximum levels were also correlated with fat score. Male Bramblings showed no relationship of corticosterone dynamics with body condition. Furthermore, there was no relationship to plumage variability (i.e. from black plumage on the head and upper thorax to grey, streaked, female-like males). Although several avian species have been shown to reduce their adrenocortical responsiveness to acute stress in severe environments, these data suggest that other factors may regulate the hypothalamo-pituitary-adrenal cortex axis as well.

Bird collisions with power lines — an experiment with ptarmigan ( Lagopus spp.)

The number of ptarmigan ( Lagopus lagopus and L. mutus) killed along three power-line sections through colliding with the overhead wires was recorded over a 6-year period in a subalpine habitat in southern Norway. The effect of an experimental removal of the power-line earth wire (common neutral) was evaluated on one of the power-line sections, by comparing the number of mortalities found before removal with the number found afterwards. The two other power-line sections in the same area were used as control sections. The number of collisions was approximately halved after the lower earth wire was removed, thus confirming the expectation that there is a connection between the number of overhead wire levels (vertically) and the collision rate. The results from this and earlier studies indicate that a reduction in overhead wire levels has a general positive effect by reducing the collision rate. The power companies should develop alternative engineering designs and critically assess constructing power lines with continuous earth wires.

Re-assignment of the Affinities of the Fossil Pollen Type Tricolpites trioblatus Mildenhall and Pocknall to Wilsonia (Convolvulaceae) and a reassessment of the ecological interpretations

Tricolpites trioblatus Mildenhall and Pocknall was described from Upper Miocene–Pliocene sediments of New Zealand and attributed to the Hebe complex (Scrophulariaceae), which is common in the New Zealand vegetation, especially in montane and subalpine habitats. Pollen in Miocene–Pliocene sediments in central Australia is identified with T. trioblatus, and the depositional situations included shallow lakes, with fresh or brackish waters, sometimes becoming saline. The affinities of T. trioblatus are re-examined in the light of these disparate environments in Australia and New Zealand. It has been found that all the fossil grains examined are more comparable to pollen of Wilsonia, and perhaps Cressa (Convolvulaceae), than to those of the Hebe complex. Wilsonia and Cressa are found in salt marshes, hence affinities with them are ecologically more credible for central Australia. T. trioblatus is found in late Eocene sediments deposited under episodic marine transgressions; an environment likely to stimulate the evolution of new species tolerant to saline conditions.

Energetics and survival of birds in extreme environments

Andreev, A.V. 1999. Energetics and survival of birds in extreme environments. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 70 (1): 13–22. As northern climates changed towards those existing at present, bird taxa kept evolving forms adapted to the variety of high-latitude habitats—inland, coastal and alpine. These habitats are structurally simple and dominated by dramatic seasonality and permafrost. These adaptations are expressed in several seasonal and regional avifaunas which include the 2G25 resident bird species of the Siberian taiga, and some 15–45 typical summer visitors to hypoarctic, subalpine and tundra habitats. The survival strategies of birds in these extreme habitats are discussed in the light of experimental data and observations gathered during the seemingly most stressful periods of the birds' annual life cycle, namely mid-winter in north-eastern Asia and incubation on permafrost in upland tundra. Of the subarctic residents, only grouse utilise predictable browse foods, but have to cope with its low energy content. Winter survival in other taxa depends on utilising fall harvests and individual energy stores. In all cases, the energy utilisation in wintering birds appears to be minimised. In summer, non-resident birds treat their local resources in quite a different way with no evidence of direct energy limitation on reproduction, including incubation. There is little evidence of individual cost-minimisation strategies. Instead, local population-resource balances are regulated through a variety of social mechanisms.

Are Alpine Bank Voles Larger and More Sexually Dimorphic because Adults Survive Better?

Microtine body weights vary temporally and geographically: they are low before the onset of winter and are highest in northern cyclic populations, particularly at peak densities, as well as in island populations. Adaptive explanations have focused on the relationships between body weight, age-specific reproductive and survival rates as well as on population dynamics. We live-trapped five populations of bank voles for up to five years in the French Alps in subalpine habitats: two spruce forests, a deciduous forest, a hedgerow network, and a boulder field recolonized by birch and spruce. Population dynamics were non-cyclic, characterized by seasonal fluctuations. Densities were generally high, with little variability among years. Survival rates were higher (0.80 to 0.90 per month), both during summer and winter, than reported from other populations of bank voles in Europe, or of microtines in general. Survival rates varied little among years, despite large variation in snow depth and duration of snow cover, and were similar between males and females. Sex ratio was generally biased towards males (average proportion of males: 0.59). Body weights were higher than for lowland or northern European populations, both for adults in the spring and for subadults at the onset of winter. The latter difference was particularly large, autumn body weights being 50% higher than in these other populations. Difference between autumn and spring weights was therefore much reduced compared with northern populations. Moreover, sexual dimorphism was the inverse of what is known for other populations in which males are smaller than females, males being larger than females during the breeding season in all populations studied here. We suggest that the overall larger body weight is a consequence of a higher survival rate selecting for lower reproductive effort and a higher somatic allocation, and that the reversed sexual dimorphism is a consequence of more intense sexual selection among males, deriving from a larger body size, and possibly also from a male-biased sex ratio. We discuss the importance of food, habitat heterogeneity and predation in shaping life histories and population dynamics of microtines. Lower impact of predation, possibly resulting from the absence or scarcity of weasels, is one possible cause for the observed higher survival rates, and consequently larger body size of the alpine bank vole.

Pikas (Ochotona princeps : Lagomorpha) as allogenic engineers in an alpine ecosystem.

Pikas (Ochotona princeps: Lagomorpha) build caches of vegetation ("haypiles"), which serve as a food source during winter in alpine and subalpine habitats. Haypiles appear to degrade over time and form patches of nutrient-rich soils in barren talus and scree areas. We sampled soils underneath and next to haypiles, and plants growing on and near haypiles in an alpine cirque in northwestern Wyoming, USA, to determine the effects of pika food caches on N, C, and C/N ratios in soils and plants. We found that (1) haypile soils had significantly higher carbon and nitrogen levels and lower C/N ratios than both adjacent soils and soils in the general study area, (2) two of three plant species tested (Polemonium viscosum and Oxyria digyna) had significantly higher levels of tissue percent N when growing on haypile soils, and (3) total standing plant biomass at the study site increased with soil percent N suggesting that vegetation was nitrogen limited. Pikas may therefore function as allogenic ecosystem engineers by modulating nutrient availability to plants.

Breeding Distribution, Migrations and Conservation Status of the Great Knot Calidris tenuirostris in Russia

SummaryAll known published and unpublished Great Knot Calidris tenuirostris breeding records, and probable breeding indications, have been reviewed. For 15 sites, breeding is confirmed by nests or unfledged chicks. The available information allows a general delineation of the breeding range to be made, although in some cases this is very approximate. The species occupies alpine and subalpine habitats in north-east Siberia and north Far East Russia at, and above, the upper tree line, at altitudes below 1000 m asl in the eastern half and usually above 1000 m asl in the western half of the breeding range. Vegetation mapping is used to assist in defining the probable breeding range. Literature, specimens and unpublished data from several observers are used to characterise the migrations of Great Knot within the Russian part of the East Asian—Australasian Flyway. On northward migration, birds pass nonstop through the region for a few days in late May; a limited number of emergency stop-over sites have been identified. In contrast to previous views, only a few non-breeding Great Knots occur on the Russian Far East coast. Post-breeding migration starts in late June and seems to occur in three waves in the northern Sea of Okhotsk up to early September. There are indications that non-breeders, failed breeders and females migrate southward first, followed by males which have bred successfully. The final wave consists of young birds. In the more southern regions, the first migration wave is not pronounced, and migration of young birds lasts through October. Estuaries and bays in the north-eastern and north-western parts of the Sea of Okhotsk and in northern Sakhalin Island are very important staging areas on southward migration. These are almost certainly being used for refuelling before long non-stop flights further south towards Australia.

Habitat Suitability Study for the Conservation of the Volcano Rabbit (Romerolagus diazi)

The endangered Mexican volcano rabbit (Romerolagus diazi)-habitat relationship was investigated. Data, obtained from 137 sampling units in 14 patches of the geographical distribution areas of the rabbit, included information on floristic composition, vegetation structure, terrain characteristics and human activities. The abundance of the volcano rabbit was measured in 685 subsampling units by pellet-counts and estimations of pellet-coverage. Two questions have been addressed in this paper: what is a good indicator of habitat type and which are the habitat factors that explain best the distribution of the volcano rabbit? Thirteen plant communities were identified. Terrain and landscape units were distinguished through aerial photograph interpretation and were verified in the field. By means of classical (parametric and non-parametric) and multivariate (Canonical Correspondence Analysis) statistical analyses, the most suitable, suitable and unsuitable habitat classes were detected. The results indicated that plant communities (F = 4,14; P < 0.0001) and landscape units (F = 7,29; P < 0.001) were adequate levels to distinguish habitat types for the rabbit. Plant communities of Festuca tolucensis and Trisetum altijugum-Festuca tolucensis attained the largest abundance of rabbits, followed by the communities Muhlenbergia quadridentata-Pinus hartwegii, Festuca tolucensis-Pinus hartwegii and Pinus sp.-Alnus firmifolia. The abundances of the volcano rabbit in the remaining plant communities were significantly less than in the communities mentioned above. These results suggest that the volcano rabbit shows strong preferences for subalpine habitat types. Soil moisture (r = -0.840), altitude (r = -0.756), grazing (r = -0.423) and burning (r = 0.494) correlated significantly with the distribution and abundance of the volcano rabbit. These results are discussed in light of their role in the conservation of the volcano rabbit.

95/05383 Practical management of chemicals and hazardous wastes. An environmental and safety professional's guide

We present a rule-based, event-driven model of foraging behavior, and use it to demonstrate the influence of structure and variability of habitats in determining the foraging efficiency of an individual herbivore. The structural and distributional properties of resources were assigned based on vegetation measurements in subalpine habitats in Denali National Park and Preserve, Alaska. The forager was characterized in terms of the physical, physiological, and cognitive attributes of a moose (Alces alces). We modelled movement as a sequence of steps in response to perceived resources. Simulation of foraging behavior in the model was event-driven. Artificial habitats were simulated to evaluate the influence of biomass per plant and mean bite size of plants on the foraging efficiency of the simulated animal. The mean rate of dry matter intake, and the 24-h activity budgets simulated by the model were similar to those reported for moose by Risenhoover. Foraging efficiency varied with changes in the size and variability of plants and individual bites available in the habitat. We discuss the results of our simulations in terms of modelling at the individual level.

Coincidences between different landscape ecological zones and growth forms of Cembran pine (Pinus cembra L.) in subalpine habitats of the Central Alps

The ‘forgotten’ depots of the European Nutcracker (Nucifraga c. caryocatactes) often ‘lead’ to the development of tufts of Pinus cembra. In many cases the other individuals of such tufts are not suppressed by the fittest one, rather there is an intraspecific coexistence up to the senescent stage of the trees. There are fusions of separate trunks, and so frequently the individual history of older trees can only be reconstructed by studying sutures, crown structures or trunk cross sections. Different types of trunk fusions are worked out. By means of transect counting the occurrence of these ‘multiple trunk trees’ is documented quantitatively in different landscape ecological zones of the Engadin region (the Grisons, Switzerland). The data base is 3024 counted microsites of Pinus cembra individuals arising from seeds, including 5272 living individuals. These ‘multiple trunk trees’ significantly play an important role in the landscape ecological zones of recent glacier recession and at the alpine timberline. Their growth forms have a higher biomechanical stability.

Climatic Influences on the Growth of Subalpine Trees in the Colorado Front Range

We examined variations in tree growth responses to climatic variations among different tree species and habitat types in the subalpine zone of the Colorado Front Range. We constructed 25 tree ring site chronologies (11 of Picea engelmannii, 9 of Abies lasiocarpa, 4 of Pinus contorta var. latifolia, and 1 of Pinus flexilis) from a series of subalpine habitats ranging from xeric to wet. To establish tree growth responses to climatic variation, we used correlation and response function analyses to compare variations in ring widths with monthly temperature and precipitation records. At the driest sites, growth of Picea and Abies tracked climatic variation similarly. At mesic and wet sites, however, these species differed in their responses to climatic variation. The responses of Pinus contorta, sampled over a narrower range of habitat types, differed from those of Picea and Abies but did not differ among sites. Steep environmental gradients in the subalpine zone of the Front Range accounted for most of the observed differences in growth responses to climatic variation. Even at adjacent sites that differ only slightly in topographic position, tree growth responses to climatic variation were distinct. Interspecific differences in response to climatic variations generally were less important than site differences. Intersite differences in tree growth responses to climatic variation can be used as indicators of environmental differences among subalpine habitats.

Habitat heterogeneity and foraging efficiency: an individual-based model

We present a rule-based, event-driven model of foraging behavior, and use it to demonstrate the influence of structure and variability of habitats in determining the foraging efficiency of an individual herbivore. The structural and distributional properties of resources were assigned based on vegetation measurements in subalpine habitats in Denali National Park and Preserve, Alaska. The forager was characterized in terms of the physical, physiological, and cognitive attributes of a moose ( Alces alces). We modelled movement as a sequence of steps in response to perceived resources. Simulation of foraging behavior in the model was event-driven. Artificial habitats were simulated to evaluate the influence of biomass per plant and mean bite size of plants on the foraging efficiency of the simulated animal. The mean rate of dry matter intake, and the 24-h activity budgets simulated by the model were similar to those reported for moose by Risenhoover. Foraging efficiency varied with changes in the size and variability of plants and individual bites available in the habitat. We discuss the results of our simulations in terms of modelling at the individual level.

The Effect of Predispersal Seed Predators on Colonization of Aster ledophyllus on Mount St. Helens, Washington

-Aster ledophyllus, a wind-dispersed herbaceous perennial of western Cascade subalpine zones, is slowly reinvading subalpine habitats devastated by the 1980 eruption of Mount St. Helens. This aster is subject to heavy predispersal seed losses due to grazing by elk (Cervus canadensis) and to seed predation by a variety of insect larvae. Because reinvasion is slow, we hypothesized that these herbivores may be limiting the colonization rate of this species. We tested this hypothesis with a two-way factorial experiment in which the two classes of seed predators (elk or insects) were either excluded from or allowed access to Aster individuals. We quantified treatment effects using two response variables: (1) seed production during the year of the manipulations and (2) seedling recruitment in the following year. Elk browsing significantly reduced both seed production and seedling recruitment, with larger plants being most affected by the elk. No significant effects, however, were detected for insect seed predators.

Revision of the New Guinean genus Mallomys (Muridae: Rodentia), with descriptions of two new species from subalpine habitats

Revision of the New Guinean genus Mallomys (Muridae: Rodentia), with descriptions of two new species from subalpine habitats

Validation ofPachyornis australisOliver (Aves; Dinornithiformes), a medium sized moa from the South Island, New Zealand

Abstract On the basis of new material, the crested moa, Pachyornis australis, which was synonymised with the heavy footed moa, P. elephantopus (Owen), by Cracraft in 1976, is re-established as a valid species and redescribed. From its distribution data I conclude that this bird primarily occurred in subalpine habitats; its remains are rare because subfossil deposits. in the subalpine zone are rare and restricted to karst regions. Extensive comparisons of bones of P. australis with those of P. elephantopus and Euryapteryx geranoides (Owen) are giyen to facilitate their correct identification. With the reinstatement of P. australis as a valid species, the number of moa taxa recognised in New Zealand is 11.

EFFECT OF WATER STRESS ON STOMATAL AND PHOTOSYNTHETIC RESPONSES IN SUBALPINE PLANTS TO CLOUD PATTERNS

Daily cloudcover is a frequent and persistent environmental feature of subalpine habitats. Response patterns in net photosynthesis (A), stomatal conductance to water vapor diffusion (g), transpiration (E), and water use efficiency (WUE = A/E) to intermittent cloudcover were evaluated for two subalpine species to determine if their responses supported the hypothesis that species that undergo water stress during sunlit intervals may have more rapid and greater stomatal responses to irradiance fluctuations than species under little apparent water stress. In Helianthella quinquenervis, a herbaceous perennial with midday xylem pressure potential &lt; –2.0 MPa, responses in both A and g to simulated changes in natural irradiance occurred almost simultaneously and were relatively rapid. Although A was reduced by 22% during periods of shade compared with full sunlight periods, E was similarly reduced, and thus, no reduction in WUE occurred. In contrast, the riparian herb Senecio triangularis was under little apparent water stress and g was relatively insensitive to fluctuations in irradiance. As a result, periods of cloudcover led to a smaller reduction in A of only 15% relative to full sunlight with little concurrent reduction in E, leading to a corresponding 12% decrease in WUE compared with steady state values under full sunlight. These data suggest that species that experience apparent water stress during sunlit intervals may maintain higher WUE during intermittent cloudcover through water conservation at the expense of carbon gain. In contrast, species in which water stress does not occur during sunlit intervals can maximize carbon gain at the expense of reduced WUE. The degree of competition for water and sunlight in a habitat may determine the particular physiological response pattern expressed during natural cloudcover regimes.

Mechanisms of Early Primary Succession in Subalpine Habitats on Mount St. Helens

In the 6 yr following the 1980 eruption of Mount St. Helens in Washington state, vascular plant invasion of barren substrates in subalpine habitats has been limited despite the proximity of seed sources from resprouted vegetation. From 1983—1985 we counted 1st—yr seedlings and estimated percent cover of adults in grids of permanent plots located across the ecotone between residual vegetation and barren substrate created in 1980. We found that (1) seedling recruitment declined from 1983 to 1985, apparently in response to drought; (2) most seedlings occurred within 3 m of a conspecific adult; and (3) plots with an intermediate vegetation cover (5—72%) contained a significantly higher fraction of seedlings than did unvegetated plots. Thus, dispersal is limited in many species and nurse plants may play a key role in trapping seeds and promoting seedling establishment. We sowed 16 000 viable seeds from 22 subalpine species into 264 plots in barren substrates at two sites on the volcano. The design was a complete factorial, with species, site, and fertilizer as treatments. Survivorship through 1985 varied from 0 to 12%, with Sitanion jubatum, Stipa occidentalis, Polygonum newberryi, Eriogonum pyrolifolium, and Spraguea umbellata attaining the highest values. Survivorship was correlated with seed mass, and was higher at the site where the pre—eruption surface was exposed. Fertilizer increased the size of most seedlings but had only a marginal effect on survivorship. Species with high environmental tolerance generally dispersed short distances, whereas species that dispersed farther generally had low tolerances and apparently require site amelioration prior to establishment. The path of early succession depends upon the spatial position and dispersal abilities of species in the seed pool, and may not reflect environmental gradients.

The life cycles and growth of Carabus glabratus and C. violaceus in Budalen, central Norway

Abstract. 1. The seasonal activity patterns of adults and larvae, and the seasonal development of female gonads showed that Curubus glabrafus Payk. and Curubus violaceus L. living in a subalpine habitat are spring (summer) breeders with biennial life cycles.2. As a rule, the adults and third stage larvae hibernate, but C.glubrutus at least can hibernate also at the second larval stage, particularly in years in which unfavourable climatic conditions in the spring delay breeding.3. The adaptive strategies underlying these life history patterns and their possible significance for species diversification and coexistence are discussed.

Dispersal of Whitebark Pine Seeds by Clark's Nutcracker: A Mutualism Hypothesis

(1) Clark's nutcrackers (Nucifraga columbiana) store a mean of only 3.7 whitebark pine (Pinus albicaulis) seeds per cache, which reduces competition for moisture and space. The mean depth at which seeds are stored, 2.0 cm, is compatible with germination requirements, and many sites selected appear suitable for seed germination. (2) One nutcracker stores about 32 000 whitebark pine seeds at subalpine elevations each year, which represent 3-5 times its energetic requirements. Although parent nutcrackers feed stored seeds to juveniles, in some years there is probably an excess of seeds stored by the population as a whole. (3) Experimental results suggest that seeds retrieved from nutcracker caches are as viable as seeds extracted by hand from cones and that seedlings originating in nutcracker caches have a good survival rate: 56% over the first year and 25% by the fourth year. (4) In comparison with Clark's nutcracker, alternative disperal agents, i.e. rodents and cone disintegration, disperse fewer seeds, disperse seeds shorter distances from parent trees, place seeds in sites less suitable for germination, and/or make large seed caches which lower reproductive potential. Nutcrackers disseminate seeds throughout the subalpine habitat and are, in part, responsible for the 'pioneering' status of whitebark pine. (5) The evolution of wingless seeds and indehiscent cones in the Cembra pine group was probably a consequence of seed dispersal by an ancestral nutcracker form. It appears that the Clark's nutcracker-whitebark pine interaction is both coevolved and mutualistic.