Previous Autumn Research Articles

Genetic parameters of spontaneous spring ovulatory activity in Mérinos d'Arles sheep

The genetic parameters of spontaneous spring ovulatory activity were investigated in the Merinos d'Arles breed under the usual pastoral and transhumant management conditions of this breed in southeastern France. Ovulatory activity was determined by assaying the plasma progesterone concentration in two blood samples taken 8-10 days apart. The data set consisted of 1 887 ovulatory activity performance measurements in 1995, 1996 and 1997 on 933 ewes, daughters of 176 rams. The effects of the 'physiological status' (hoggets, adult ewes with or without lambing in the previous autumn), age and live weight just before the mating period were found to be highly significant. They were included in the linear animal model and the threshold sire model used to estimate genetic parameters. On average, 27.9 % of ewes exhibited ovulatory activity in April. Age and live weight just before the mating period had a marked positive effect on ovulatory activity. A difference of about 8-9 % was observed between extreme classes for these factors. The heritability and repeatability estimated through the linear model were 0.20 (standard error: 0.04) and 0.30 (0.07), respectively. When using the threshold model, the heritability was 0.37. These values led us to conclude that a genetic approach for improving spontaneous spring ovulatory activity should be further developed. Nevertheless, further studies are necessary to determine all the implications of such selection. © Inra/Elsevier,

Density and mortality of overwintering Oscinella frit and other oscinellids in Swedish grasslands

Aiming to assess the mortality of the overwintering generation of Oscinella frit, populations of oscinellid flies and their parasitoids were sampled during five consecutive years, before and after overwintering. Samples were taken in permanent pastures, leys and ryegrass plots in Sweden. Densities of O. frit were higher in pastures than in leys. The percentage of oscinellids parasitized showed little variation among years, but was higher in ryegrass plots (37%) than in pastures (14%). The parasitoid complex was dominated by one species, Rhoptromeris heptoma. The percentage decline in density of unparasitized O. frit from autumn to spring ranged from 5 to 65% during the five studied winters. This mortality was not related to O. frit density in autumn, nor were any weather effects found. My results suggest that the yearly variation in mortality of overwintering O. frit is moderate and that, consequently, during most years it should be possible to predict spring population size based on population estimates made the previous autumn.

Estimating late-winter heat flow to the atmosphere from the lake-dominated Alaskan North Slope

AbstractThe conductive heat flux through the snow cover (Fa) is used as a proxy to examine the hypothesis that there is a significant heat flow from the Alaskan North Slope to the atmosphere because of the large number of lakes in the region.Fais estimated from measurements of snow depth, temperature and density on tundra, grounded ice and floating ice in mid-April 1997 at six lakes near Barrow, northwestern Alaska. The meanFavalues from tundra, grounded ice and floating ice are 1.5, 5.4 and 18.6 W m2, respectively. A numerical model of the coupled snow/ice/water/soil system is used to simulateFaand there is good agreement between the simulated and measured fluxes. The flux from the tundra is low because the soils have a relatively low thermal conductivity and the active layer cools significantly after freezing completely the previous autumn. The flux from the floating ice is high because the ice has a relatively high thermal conductivity, and a body of relatively warm water remains below the growing ice at the end of winter. The flux from the grounded ice is intermediate between that from the tundra and that from the floating ice, and depends on the timing of the contact between the growing ice and the lake sediments, and whether or not those sediments freeze completely. Using the estimatedFavalues combined with the areal fractions of tundra, grounded ice and floating ice derived from synthetic aperture radar images, area-weightedFavalues are calculated for six areas.Favalues for the ice vary between 9.8 and 13.8 W m−2, and those from the ice plus tundra vary between 3.9 and 5.3 W m−2. TheFavalues are similar to those observed in the sea-ice-covered regions of the south and north polar oceans in winter. The North Slope of Alaska may thus make a significant contribution to the regional energy budget in winter.

Estimating late-winter heat flow to the atmosphere from the lake-dominated Alaskan North Slope

AbstractThe conductive heat flux through the snow cover (Fa) is used as a proxy to examine the hypothesis that there is a significant heat flow from the Alaskan North Slope to the atmosphere because of the large number of lakes in the region. Fa is estimated from measurements of snow depth, temperature and density on tundra, grounded ice and floating ice in mid-April 1997 at six lakes near Barrow, northwestern Alaska. The mean Fa values from tundra, grounded ice and floating ice are 1.5, 5.4 and 18.6 W m2, respectively. A numerical model of the coupled snow/ice/water/soil system is used to simulate Fa and there is good agreement between the simulated and measured fluxes. The flux from the tundra is low because the soils have a relatively low thermal conductivity and the active layer cools significantly after freezing completely the previous autumn. The flux from the floating ice is high because the ice has a relatively high thermal conductivity, and a body of relatively warm water remains below the growing ice at the end of winter. The flux from the grounded ice is intermediate between that from the tundra and that from the floating ice, and depends on the timing of the contact between the growing ice and the lake sediments, and whether or not those sediments freeze completely. Using the estimated Fa values combined with the areal fractions of tundra, grounded ice and floating ice derived from synthetic aperture radar images, area-weighted Fa values are calculated for six areas. Fa values for the ice vary between 9.8 and 13.8 W m−2, and those from the ice plus tundra vary between 3.9 and 5.3 W m−2. The Fa values are similar to those observed in the sea-ice-covered regions of the south and north polar oceans in winter. The North Slope of Alaska may thus make a significant contribution to the regional energy budget in winter.

Estimating late-winter heat flow to the atmosphere from the lake-dominated Alaskan North Slope

AbstractThe conductive heat flux through the snow cover (Fa) is used as a proxy to examine the hypothesis that there is a significant heat flow from the Alaskan North Slope to the atmosphere because of the large number of lakes in the region. Fa is estimated from measurements of snow depth, temperature and density on tundra, grounded ice and floating ice in mid-April 1997 at six lakes near Barrow, northwestern Alaska. The mean Fa values from tundra, grounded ice and floating ice are 1.5, 5.4 and 18.6 W m2, respectively. A numerical model of the coupled snow/ice/water/soil system is used to simulate Fa and there is good agreement between the simulated and measured fluxes. The flux from the tundra is low because the soils have a relatively low thermal conductivity and the active layer cools significantly after freezing completely the previous autumn. The flux from the floating ice is high because the ice has a relatively high thermal conductivity, and a body of relatively warm water remains below the growing ice at the end of winter. The flux from the grounded ice is intermediate between that from the tundra and that from the floating ice, and depends on the timing of the contact between the growing ice and the lake sediments, and whether or not those sediments freeze completely. Using the estimated Fa values combined with the areal fractions of tundra, grounded ice and floating ice derived from synthetic aperture radar images, area-weighted Fa values are calculated for six areas. Fa values for the ice vary between 9.8 and 13.8 W m−2, and those from the ice plus tundra vary between 3.9 and 5.3 W m−2. The Fa values are similar to those observed in the sea-ice-covered regions of the south and north polar oceans in winter. The North Slope of Alaska may thus make a significant contribution to the regional energy budget in winter.

Involvement of endogenous plant hormones (IAA, ABA, GAs) in leaves and flower bud formation of satsuma mandarin ( Citrus unshiu Marc.)

Plant hormones (IAA, ABA, GA 1/3, GA 4/7) contents in the leaves of satsuma mandarin trees ( Citrus unshiu Marc. `Okitsu') were measured to elucidate the relationship between endogenous plant hormones and flower buds formation. The ringing treatment to lateral branch in October enhanced the percentage of leafless inflorescence and number of flowering shoots in the following spring. While, more vegetative spring shoots were formed on bearing shoots which were left the fruit load in the previous autumn to winter. GA 1/3 were the dominantly detected GAs in the leaves. Their content was higher in the leaves of the bearing shoots than in that of the vegetative shoot but was not affected by the ringing treatment. Ringing increased the percentage of leafless inflorescence and the contents of IAA and ABA in December. These results suggested that flower bud formation was inhibited by GA 1/3 in October, and that high IAA and ABA content in December also promote the percentage of leafless inflorescence and the number of flower buds per node. The relationship between endogenous plant hormones and flower bud formation was discussed.

“Cam Ye O'er Frae France?” Exile and the Mind of Scottish Jacobitism, 1716–1727

On 14 February 1716 at Ruthven in Badenoch, the remaining officers of the Jacobite army in Scotland gathered to decide their next move. They had turned out the previous autumn in high hopes of restoring the Stuart dynasty to the throne it had lost in 1689 and forcing an end to the union with England, but their confidence and enthusiasm had long since evaporated in the face of the defeat of the English rising at Preston and failure on their own part at Sherrifmuir. Their king and his chief minister had fled the country just after the army began its retreat from Perth. Now the weather had deteriorated, and desertion had reduced their once impressive force to a shadow of its former self. Not surprisingly, given the circumstances, the officers drafted a letter to the duke of Argyll, the commander of the British army in Scotland, asking for an indemnity and ordered their men to make their own way home. Then they themselves dispersed. It was the final act in the botched complex of conspiracies and uprisings that has gone down in history as the Jacobite Rising of 1715.Reflecting on the consequences of the Jacobites' failure, the earl of Mar, by then the Old Pretender's secretary of state, sadly remarked: “I much doubt if ever a [rising] can be established there again.” It was a percipient observation. For over a generation, it was to prove extremely difficult to persuade most of the leaders of Scottish Jacobitism even to contemplate another uprising.

Increased abundance of the red admiral butterfly Vanessa atalanta in Britain: the roles of immigration, overwintering and breeding within the country

The migratory butterflyVanessa atalantaincreased in abundance at monitored sites in Britain from 1976 to 1996. Three possible causes of the increase are improved winter survival within Britain, greater breeding success within Britain, and increased immigration. Trends during most of the season were similar to those of immigrant or overwintered individuals in spring; thus the evidence does not support greater breeding success in Britain. As abundance in spring was not correlated with abundance in the previous autumn, when trend was taken into account, it seemed unlikely that overwintering in Britain was important. Thus the increase in abundance was probably due to increased immigration. Incidental to the main study, the mean index per site per year was closely correlated with the collated index, the usual measure of annual fluctuations. This agreement suggests that the mean index may be a useful check for trends in monitoring data for other wide‐ranging organisms.

Storage of foliar-absorbed nitrogen and remobilization for spring growth in young nectarine (Prunus persica var. nectarina) trees.

The effectiveness of spraying foliage with urea to provide nitrogen (N) to augment the seasonal internal cycling of N in young nectarine trees (Prunus persica (L.) Batsch var. nectarina (Ait. f. Maxim.), cv. Stark Red Gold) was studied. One-year-old trees were grown with contrasting N supplies during the summer and foliage was sprayed with a 2% urea solution labeled with (15)N just before leaf senescence started. After leaf abscission had finished, the trees were repotted in sand and given no further N. Remobilization of both labeled and unlabeled N for leaf growth the following spring was quantified. Leaves absorbed between 58 and 69% of the (15)N intercepted by the canopy irrespective of tree N status. During leaf senescence, the majority of (15)N was withdrawn from the leaves into the shoot and roots. Remobilization of (15)N the following spring was also unaffected by tree N status. About 38-46% of (15)N in the trees was recovered in the new growth. More unlabeled N (derived from root uptake) was remobilized for leaf growth in the spring than was withdrawn from leaves during canopy senescence the previous autumn. Therefore, soil-applied N augmented N storage pools directly, and contributed more to N remobilization the following spring than did foliar-absorbed (15)N.

Occurrence and etiology of death of young olive trees in southern Spain

New plantations of olive tree in southern Spain are being severely affected by wilt or dieback and death, which has been locally called ‘Drying Syndrome’. To determine the etiology of this problem, a study was carried out in samples of affected young trees collected during a seven year period (1989‐1995), and in two field surveys in 1994‐95 and 1996. Besides some insect damage and agronomic problems, the ‘Drying Syndrome’ was associated with Verticillium wilt, winter frost and root rot fungi. Although ‘Drying Syndrome’ can be distinguished from Verticillium wilt, the latter was included in this study, since, frequently, Verticillium wilt symptoms were unspecific and Verticillium dahliaecould not be always isolated in the diagnostic work that preceded this study. Early winter frost caused a vascular necrosis and wilt of the young olive trees. This unusual and severe damage was related with the lack of frost hardiness due to warm temperatures during the previous autumn. Root rot fungi were very frequent in the samples of diseased olive trees of field or nursery origin, and they were the main cause of ‘Drying Syndrome’ in the second field survey, when a heavy rainfall level occurred during winter. Pathogenicity tests showed that five fungal species ( Cylindrocarpon destructans, Phytophthora megasperma, P. palmivora, Pythium irregulare and Sclerotium rolfsii) were pathogenic to olive trees and reproduced symptoms of ‘Drying syndrome’ in rooted cuttings of cultivar Picual. Other fungal species associated with root rot of olive trees in the field or in the nurseries, including Fusarium acuminatum, F. eumartii, F. oxysporum, F. solani, Macrophomina phaseolina and Rhizoctonia solani, were weakly or not pathogenic. Pathogenicity of P. megasperma, P. palmivoraand P. irregulare depended on soil water content, since isolates tested caused extensive root rot and sudden plant death only when the soil was continuously waterlogged. The high frequency of P. megasperma in waterlogged field soils and its pathogenicity dependence on soil water content suggest that this pathogen may play an important role in the well known sensitivity of young olive trees to ‘root asphyxiation’. Abbreviations: DS ‐ drying syndrome of young olive trees; PHSC ‐ plant health service in C´ ordoba (Spain).

Redistribution of 14C-labelled reserve carbon in Pinus sylvestris seedlings during shoot elongation

This study examined the later use of 14C reserves formed in previous autumn in Scots pine (Pinus sylvestris L.) seedlings. The seedlings were allowed to photosynthesise 14CO2 in early September when shoot and needle growth was over. The following spring the seedlings were harvested in five samplings during the shoot growth period. The distribution and concentration of 14C were determined and the results were compared with the growth data. It was observed that reserves were not used markedly for the new growth. Most of the 14C was found in one-year-old needles (30–40%) and in the root system (40–50%) which was due to both their high activity as a storage sink and their large sink size. The high initial 14C-activity in the finest roots decreased indicating respiration of reserves. Only a small percent of the reserve carbon was found in the new shoots which indicated that reserves are of minor importance in building a new shoot. An allocation of about 15% of the autumn storage to the stem suggested that in seedlings the stem is of minor importance as a storage organ.

Timing and Synchrony of Parturition in Alaskan Caribou

Timing of parturition of caribou ( Rangifer tarandus ) varies within populations, but the relative influences of nutritional condition of females during the autumn breeding season and during gestation on that variation is not known. We determined timing of parturition of caribou in Denali National Park, Alaska, during 1984–1995, which had wide variation in snowfall that influenced nutritional condition and productivity of females. The first young were observed each year between 4 and 15 May. Annual median dates of parturition for radiocollared females during 1987–1995 varied from 13 to 21 May. Synchrony of births (i.e., proportion of births during 7 days centered on the median date) did not vary significantly among years ( P > 0.05). Females ≤4 years old were more likely to give birth after the annual median date than older females ( P = 0.005). Dates of parturition were significantly correlated with masses of females in the previous autumn ( P = 0.034) but not in late winter ( P = 0.155). Births tended to be earlier for parous females that were not lactating during the previous breeding season compared to those that were lactating ( P = 0.030). Annual onsets of parturition varied significantly with snowfall in late winter prior to conception ( P = 0.012) but not with snowfall during gestation. Timing of parturition in our study appeared to be a function of physical condition of breeding females in autumn.

Comparison of the marine survival of atlantic salmon, Salmo solar L. smolts vaccinated and nonvaccinated against vibriosis

The effect of vaccination against vibriosis on the marine survival of one-year-old smolts and two size-classes of two-year-old smolts of the short-migrating River Neva stock of Atlantic salmon ( Salmo salar L.) was studied through paired releases of Carlin-tagged fish in the Bothnian Sea (Baltic Sea) in 1991 and 1992. Vibriosis was supposed to contribute to the poor survival of post-smolts in the Bothnian Sea compared to the Gulf of Finland. Vaccinated groups were immunized with a single intraperitoneal injection the previous autumn with a commercial vaccine containing formalin-killed Vibrio anguillarum and V. ordalii bacteria incorporating aluminium sulphate as adjuvant. The experiment was designed in advance to detect a departure of 20–25% from the initial 50:50 stocking ratio of vaccinated and nonvaccinated fish at a 5% risk level and 90% power. The difference was substantial and could thus explain a significant proportion of the differences in stocking results between the Gulf of Finland and the Bothnian Sea. Tag recoveries were collected from the date of release until the end of 1995. In 1991, a total of 4000 two-year-old smolts were released, half of them vaccinated, with 588 (29.6%) tags returned from the vaccinated and 551 (27.6%) from the nonvaccinated groups. For two-year-old smolts in the 1992 year class, the corresponding numbers were 4200 released, with 347 (16.6%) and 327 (16.4%) recaptured, respectively. For one-year-old smolts in 1992, only 10 recoveries (0.5%) were obtained from both the vaccinated and nonvaccinated groups from the 4000 released, excluding the statistical analysis. For both year classes of two-year-olds, the distribution of recaptures over the years was homogeneous between vaccinated and nonvaccinated groups at a 5% risk level. The observed recapture ratios from the total number of recoveries did not differ statistically significantly ( G-test for goodness of fit) from the original stocking ratio of vaccinated and nonvaccinated fish at a 5% risk level. This indicates that vaccination did not affect survival statistically significantly.

Dendroclimatological analysis of major forest species of the central Appalachians

A dendroclimatological study was carried out in the 80-year-old Fernow Experimental Forest of the U.S. Forest Service near Parsons, West Virginia (39°20′N, 79°40′W). The relationship between radial and basal area increments and corresponding monthly, seasonal, and yearly mean air temperature and precipitation were obtained over 53 years for four species: black cherry ( Prunus serotina Ehrh.), northern red oak ( Quercus rubra L.), white ash ( Fraxinus americana L.), and yellow poplar ( Liriodendron tulipifera L.). These species show positive growth responses to rainfall of previous summer, autumn, and current summer. They show significantly inverse correlation to air temperature of the current growing season. The indices of radial increment show a close correlation to those of basal area increment. However, in our analyses, basal area increment indices are more sensitive to climatic variations than radial growth indices.

Experimental evaluation of rodent exclusion methods to reduce hantavirus transmission to humans in rural housing.

An experimental assessment of methods to reduce rodent infestations in rural housing was conducted in Yosemite National Park, California, Sequoia/Kings Canyon National Parks, California, and Shenandoah National Park, Virginia. During pretreatment surveys, nearly all (63 of 68) selected units had past or ongoing rodent activity inside. Active infestations were found in 58.8% of the units. Peromyscus spp. represented 91.2% of all animals caught inside housing units. Despite little harborage, rodent activity was common near housing (290 animals/2,254 trap nights). The most common species present was Peromyscus maniculatus (43-50% of all captures). This species was especially frequent (49-87% of Peromyscus captures) around the foundations of housing units. Habitat had little effect on captures. There were 1.8 Peromyscus caught per unit along the foundations of housing in modified rural settings with grass lawns compared with 1.2 Peromyscus caught per unit in sites located in mature woodlands. During autumn of 1994, randomly selected housing units were rodent proofed by sealing openings associated with chases, roof eaves, and attics with insulation and wire mesh. Housing was examined and the fauna was resampled in the spring-summer of 1995. Rodent-proofed houses were infested significantly less often (3 of 28) than control houses (13 of 36) (P = 0.02) and the intensity of infestation was lower in experimental houses (6 versus 23 mice/treatment). More than 25% of the mice trapped inside the houses had been marked outside the houses during the three-day surveys, demonstrating movement of mice adjacent to the buildings into not rodent-proofed housing. As in the previous autumn, most of the animals captured in (98.9%) and along the foundations of the houses (77.5%) were Peromyscus spp. These results demonstrate that Peromyscus frequently invade rural housing but rodent-proofing effectively eliminates or substantially reduces rodent activity.

Storage and remobilisation of sulphur in beech trees (Fagus sylvatica)

Three‐year‐old beech trees were fed 35S‐sulphate in August 1993 via a flap in a mature leaf of an upper branch. Harvest of beech trees was performed 24 h after feeding 35S‐sulphate, before leaf senescence, after leaf abscission, in early winter (January 1994). in late winter (March 1994). before bud break and after bud break. Twenty‐four h after feeding 35S‐sulphate, 0.7 ± 0.5% of the 35S‐radioactivity taken up was exported out of the fed leaf. When trees were analysed 2 months later, i.e., before leaf senescence, this value had increased to 22 ± 7%. The exported 35S‐radioactivity was located in the branch containing the fed leaf (2.8 ± 13%). in basipetal parts of the trunk (41 ± 77%) and in the main rool (21 ± 6%). Leaves and apical parts of the trunk were no sink organs for the exported sulphur. Along the tree axis the main proportion of the radiolabel was located in the wood, predominantly in the acid soluble fraction. In the bark the greater portion of the radiolabel was found in the acid insoluble fraction. In both tissues the bulk of the 35S of the soluble fraction was sulphate together with small amounts of glutathione. This pattern did not change until bud break. After bud break, basipetal parts of the trunk lost part of its 35S‐radioactivity. Of the 35S‐radioactivity which had been exported out of the fed leaf during the previous autumn, 16 ± 2% remained in the trunk, whereas 47 ± 7% of the 35S was found in branches, mainly in the newly developed leaves. The present results show that sulphur, mainly in the form of sulphate, is stored along the tree axis in both bark and wood of beech trees and is re‐mobilised during leaf development in spring.

Frost in Northeast Australia: Trends and Influences of Phases of the Southern Oscillation

Abstract A forecast method capable of estimating date of last frost and number of frosts per season in northeastern Australia some months in advance is described. Forecast “skill” is achieved using either Southern Oscillation index (SOI) patterns (phases) during the previous austral autumn or a linear discriminant approach and the SOI. When applying these systems, it is possible to provide significantly different probability distributions of day of last frost and number of frosts, depending on the SOI patterns observed during the previous season. An analysis of the time series of frost frequency and date of last frost suggests an apparent warming trend in the data, resulting in a trend toward earlier dates of last frost and fewer numbers of frosts at many of the locations analyzed. The beneficial implications of the proposed frost forecasting system for enterprises such as winter agriculture in the region are believed to be significant.

Population Fluctuations of Mast-Eating Rodents Are Correlated with Production of Acorns

I used a 14-year dataset on dynamics of mast-consuming rodents from an eastern deciduous forest to determine the relationship between population fluctuations of white-footed mice ( Peromyscus leucopus ), deer mice ( P. maniculatus ), and eastern chipmunks ( Tamias stria-tus ) and production of acorn mast. Mast (acorn) production was episodic with four excellent crops produced in 14 years. Densities of rodents in summer ranged from 3 to 103 animals/ha and correlated positively with production of mast the previous autumn (all r 2 > 0.56). During years of high production of mast, stores of acorn lasted throughout winter, whereas in most years, acorns were gone by January. During years of high production of mast, mice bred all winter, which resulted in high densities the following summer. Episodic production of mast and resulting fluctuations in consumers of mast have implications for the predator-satiation hypothesis and other community processes.

Factors Affecting the Relationship between Body Mass and Age in the Izard

We investigated the influence of gender, capture period, and between-year variation on the relationship between body mass and age in the izard ( Rupicapra pyrenaica ) using data obtained on 201 individuals captured in a Pyrenean reserve, France. Body mass was measured in spring or autumn 1984–1993. Absence of sexual dimorphism in body mass probably resulted from the high density of this protected population. Strong quadratic relationships between age and body mass were observed for spring and autumn ( r 2 = 0.79 and 0.76, respectively). Izards exhibit lower body mass in spring than in the previous autumn irrespective of age class. No significant between-year variation occurred in body mass in autumn. There were marked differences between years in spring that may be related to previous climatic conditions in winter, particularly daily temperature in December and total snowfall from November to April.

Dominance and survival of dippers Cinclus cinclus

Survival of dippers Cinclus cinclus in the wild was studied in relation to their dominance. Dominance was assessed amongst groups of temporary captives in a laboratory arena. Adults tended to be more dominant than juveniles, and within age classes males generally dominated females. Dominant individuals also sang more. Logistic regression was used to examine survival in the wild in relation to dominance and other factors. Annual survival of juvenile males was negatively related to dominance during the previous autumn. No significant effects of dominance on winter or annual survival were found amongst females or adult males. Dominance effects on overwinter survival approached significance for adult females, however, and were significant for both winter and annual survival when the data from adult females and juvenile males were combined. None of the other factors considered, which included body size, song frequency and year, had a significant effect on overwinter or annual survival. We concluded that dominance either had no influence on survival, or had a negative effect particularly on dippers of intermediate status. We were unable to show if dominance had a direct effect, however, or acted indirectly on survival via an unidentified factor we did not examine.