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Effect of the extreme summer heat waves on isolated populations of two orophitic plants in the north Apennines (Italy)

One of the lesser known effects of global climate change is the occurrence of heat waves. Climatic models predict that heat waves will become more intense, longer lasting and/or more frequent, as a consequence of the increased inter-annual variability and increased average values of summer temperatures. Plants are damaged by heat waves through direct effects of extreme temperatures influencing plant physiology and through indirect effects, like drought and exposure to high ozone concentration. This study investigates the flowering abundance and biomass production of two orophytic species, Alopecurus alpinus Vill. and Vicia cusnae Foggi et Ricceri following the heat wave that occurred in the summer of 2003 and analyses the effects of summer temperatures during the period 1999–2004 on the species reproductive performance. In 2003, we observed a significant decrease in the number of flowering stems and flowers per flowering stem for both species. Flower production reached its lowest value in correspondence to the heat wave in 2003 and Redundancy Analysis showed that flower production was related to the mean June temperature. Flower production was more sensitive than vegetative growth, which was maintained. This suggests that changes in reproductive strategies, e.g. changes in the ratio between sexual and clonal reproduction, may occur by as an effect of extreme weather events. Such changes may be of great importance when the population consists of a small number of flowering individuals, as is the case for A. alpinus and V. cusnae in the study area. As a consequence, although the plants generally responded positively to gradual warming, we found that, during the monitoring period 1999–2004, extreme temperatures had a negative effect on A. alpinus and V. cusnae.

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Mating dominance amongst male Himalayan tahr: blonds do better

In ungulates, rank order is determined by differences in weight, body size, weapon size and age. In the Caprini tribe (Bovidae: Caprinae), adult male Himalayan tahr are unique to show different coat colours, but no sexual dimorphism in weapons. A highly significant correlation between hair colour and rank order was found during the rut: males with a lighter coloured ruff dominated over darker ruffed ones, in both aggressive interactions and access to oestrus females. We studied colour-based dominance in relation to weight, age and testosterone levels, which establish the social rank in most ungulates. No differences in weight and testosterone concentrations were found between adult male colour classes, but males with paler ruffs were significantly younger than darker adult males. The distribution of physical traumas from fights confirmed that younger, lighter-coloured males had a higher rank than older, darker males, a pattern which is unusual amongst ungulates. Coat colour seems to work as a signal of rank in male-male aggressive interactions and it changes according to age, whereas the relevant physiological determinants deserve further research. Intrasexual male competition has not changed weapon size or shape in the Himalayan tahr, but ruff colours are apparently used to signal rank and dominance. Colour patterns of adult males may then be homologous to ritualised weapons, apparently being a unique feature of male tahr amongst mammals.

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Mating dominance amongst male Himalayan tahr: blonds do better

In ungulates, rank order is determined by differences in weight, body size, weapon size and age. In the Caprini tribe (Bovidae: Caprinae), adult male Himalayan tahr are unique to show different coat colours, but no sexual dimorphism in weapons. A highly significant correlation between hair colour and rank order was found during the rut: males with a lighter coloured ruff dominated over darker ruffed ones, in both aggressive interactions and access to oestrus females. We studied colour-based dominance in relation to weight, age and testosterone levels, which establish the social rank in most ungulates. No differences in weight and testosterone concentrations were found between adult male colour classes, but males with paler ruffs were significantly younger than darker adult males. The distribution of physical traumas from fights confirmed that younger, lighter-coloured males had a higher rank than older, darker males, a pattern which is unusual amongst ungulates. Coat colour seems to work as a signal of rank in male-male aggressive interactions and it changes according to age, whereas the relevant physiological determinants deserve further research. Intrasexual male competition has not changed weapon size or shape in the Himalayan tahr, but ruff colours are apparently used to signal rank and dominance. Colour patterns of adult males may then be homologous to ritualised weapons, apparently being a unique feature of male tahr amongst mammals.

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Response of alpine plant flower production to temperature and snow cover fluctuation at the species range boundary

Surface temperatures have risen globally during the last 30 years, especially in alpine areas. It is recognized that these increases are influencing phenology, physiology and distribution of plants. However, few studies have addressed the effects of climate warming at the species range boundary, where plants are expected to be more stressed. We analysed 11-year data sets of inflorescence production of four alpine plants (Carex foetida, Leucanthemopsis alpina, Senecio incanus, Silene suecica) at the southern boundary of their distribution range in the N-Apennines (N-Italy), in relation to air temperature and snow cover persistence. Inflorescence production of all species fluctuated greatly and was significantly affected by the variation of the mean temperature of June/July. We found significant relationships also between species data series and the snow cover persistence. Moreover, species responded differently to such parameters. One species showed a significant decrease of the reproductive effort, whereas the other three showed a stable trend of inflorescence production. We have shown that some alpine species are favoured by increased temperature and reduced snow cover even at the boundary of their range, where they are thought to be particularly sensitive to warming. However, the aptitude to cope with climate change might be limited by competition against thermophilous species migrating from lower altitude and in some cases by the low altitude of mountain peaks that prevent species upward migration. The individualistic response of species to climate change found here, support the statement that the composition of plant communities might rapidly change in the future.

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Restoring a keystone predator may endanger a prey species in a human-altered ecosystem: the return of the snow leopard to Sagarmatha National Park

Twenty-five years ago, the snow leopard Uncia uncia, an endangered large cat, was eliminated from what is now Sagarmatha National Park (SNP). Heavy hunting pressure depleted that area of most medium–large mammals, before it became a park. After three decades of protection, the cessation of hunting and the recovery of wild ungulate populations, snow leopards have recently returned (four individuals). We have documented the effects of the return of the snow leopard on the population of its main wild prey, the Himalayan tahr Hemitragus jemlahicus, a ‘near-threatened’ caprin. Signs of snow leopard presence were recorded and scats were collected along a fixed trail (130 km) to assess the presence and food habits of the snow leopard in the Park, from 2004 to 2006. Himalayan tahr, the staple of the diet, had a relative occurrence of 48% in summer and 37% in autumn, compared with the next most frequent prey, musk deer Moschus chrysogaster (summer: 20%; autumn: 15%) and cattle (summer: 15%; autumn: 27%). In early summer, the birth rate of tahr (young-to-female ratio: 0.8–0.9) was high. The decrease of this ratio to 0.1–0.2 in autumn implied that summer predation concentrated on young tahr, eventually altering the population by removing the kid cohort. Small populations of wild Caprinae, for example the Himalayan tahr population in SNP, are sensitive to stochastic predation events and may be led to almost local extinction. If predation on livestock keeps growing, together with the decrease of Himalayan tahr, retaliatory killing of snow leopards by local people may be expected, and the snow leopard could again be at risk of local extinction. Restoration of biodiversity through the return of a large predator has to be monitored carefully, especially in areas affected by humans, where the lack of important environmental components, for example key prey species, may make the return of a predator a challenging event.

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Seeds of alpine plants are short-lived: implications for long-term conservation

Background and Aims Alpine plants are considered one of the groups of species most sensitive to the direct and indirect threats to ecosystems caused by land use and climate change. Collecting and banking seeds of plant species is recognized as an effective tool for providing propagating material to re-establish wild plant populations and for habitat repair. However, seeds from cold wet environments have been shown to be relatively short lived in storage, and therefore successful long-term seed conservation for alpine plants may be difficult. Here, the life spans of 69 seed lots representing 63 related species from alpine and lowland locations from northern Italy are compared. Methods Seeds were placed into experimental storage at 45 °C and 60 % relative humidity (RH) and regularly sampled for germination. The time taken in storage for viability to fall to 50 % (p50) was determined using probit analysis and used as a measure of relative seed longevity between seed lots. Key Results Across species, p50 at 45 °C and 60 % RH varied from 4•7 to 95•5 d. Seed lots from alpine populations/species had significantly lower p50 values compared with those from lowland populations/species; the lowland seed lots showed a slower rate of loss of germinability, higher initial seed viability, or both. Seeds were progressively longer lived with increased temperature and decreased rainfall at the collecting site. Conclusions Seeds of alpine plants are short lived in storage compared with those from lowland populations/related taxa. The lower resistance to ageing in seeds of alpine plants may arise from low selection pressure for seed resistance to ageing and/or damage incurred during seed development due to the cool wet conditions of the alpine climate. Long-term seed conservation of several alpine species using conventional seed banking methods will be problematic.

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Habitat preferences of high-altitude Galliformes in Sagarmatha National Park, Nepal

In the Sagarmatha National Park, Nepal, Himalayan species of Galliformes are poorly studied and their present status is unknown. We studied the distribution of three high-altitude species: Himalayan monal, blood pheasant, and Tibetan snowcock, comparing birds' distribution in relation to altitude and habitat in spring and autumn 2007. Our study area was at 3300–5000 m a.s.l., characterized by subalpine vegetation. A structural description of vegetation types was made on the basis of main habitat features. We observed two different patterns across the year. Group size differences are common during spring and autumn. Variation in habitat use and altitudinal ranges are evident in the snowcock and blood pheasant. The Himalayan monal distribution was influenced by anthropogenic resources.

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Restoring a keystone predator may endanger a prey species in a human-altered ecosystem: the return of the snow leopard to Sagarmatha National Park

Twenty-five years ago, the snow leopard Uncia uncia, an endangered large cat, was eliminated from what is now Sagarmatha National Park (SNP). Heavy hunting pressure depleted that area of most medium–large mammals, before it became a park. After three decades of protection, the cessation of hunting and the recovery of wild ungulate populations, snow leopards have recently returned (four individuals). We have documented the effects of the return of the snow leopard on the population of its main wild prey, the Himalayan tahr Hemitragus jemlahicus, a ‘near-threatened’ caprin. Signs of snow leopard presence were recorded and scats were collected along a fixed trail (130 km) to assess the presence and food habits of the snow leopard in the Park, from 2004 to 2006. Himalayan tahr, the staple of the diet, had a relative occurrence of 48% in summer and 37% in autumn, compared with the next most frequent prey, musk deer Moschus chrysogaster (summer: 20%; autumn: 15%) and cattle (summer: 15%; autumn: 27%). In early summer, the birth rate of tahr (young-to-female ratio: 0.8–0.9) was high. The decrease of this ratio to 0.1–0.2 in autumn implied that summer predation concentrated on young tahr, eventually altering the population by removing the kid cohort. Small populations of wild Caprinae, for example the Himalayan tahr population in SNP, are sensitive to stochastic predation events and may be led to almost local extinction. If predation on livestock keeps growing, together with the decrease of Himalayan tahr, retaliatory killing of snow leopards by local people may be expected, and the snow leopard could again be at risk of local extinction. Restoration of biodiversity through the return of a large predator has to be monitored carefully, especially in areas affected by humans, where the lack of important environmental components, for example key prey species, may make the return of a predator a challenging event.

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