Rumen microbes and fermentation of wild sika deer on the Shiretoko peninsula of Hokkaido Island,Japan

A total of 32 wild Hokkaido sika deer (Cervus nippon yesoensis) were shot (13 in summer, nine in autumn and 10 in winter) in the Syari district, Shiretoko Peninsula of Hokkaido Island, Japan. The ingested foods, rumen fermentation parameters and microbes were determined to evaluate digestive strategy and food availability in each season. Ingested foods and ruminal characteristics greatly varied by season. Rumen digesta mainly comprised of graminoids in summer, graminoids and agricultural products in autumn, and bark and twigs in winter. Rumen pH showed seasonal differences (P<0.05) and was lowest in summer, highest in winter, and intermediate in autumn, reflecting the seasonal differences in ruminal concentration of total volatile fatty acids which were significantly lower (P<0.05) in winter than in summer and autumn. Acetate proportions were significantly higher in winter than in other seasons (P<0.05), while the opposite trend was seen in proportions of propionate and butyrate. Rumen ammonia levels showed significant seasonal differences (P<0.05), decreasing from summer to autumn to winter. Rumen protozoa levels in autumn and winter decreased to 28 and 10% of the levels observed in summer, respectively (P<0.05 for both). The rumen bacteria level in winter was lower (P<0.05) than that in autumn, but no difference was seen for the other seasonal comparisons. Gram negative cocci were present in significantly higher proportions in winter than in other seasons (P<0.05), while Gram negative curved rods were less frequently observed in winter (P<0.05). Based on these results, wild sika deer in this area are shown to survive with rumen microbial populations altered with the dietary conditions that vary greatly by season.     

Distribution, Movements and Growth of Young Sandbar Sharks, Carcharhinus Plumbeus, in the Nursery Grounds of Delaware Bay

During the spring and summer months of 1995, 1996 and 1997, gillnet and longline surveys were conducted in conjunction with tag and recapture experiments to outline spatial and seasonal distribution of young sandbar sharks, Carcharhinus plumbeus, in Delaware Bay for essential fish habitat mapping, to assess abundance of young sandbar sharks, and to quantify growth during the summer nursery season. Sandbar sharks (n = 943) ranging from 40 to 120cm fork length (48 to 130cm total length) were captured; yearly totals were 199, 314 and 430 in 1995, 1996 and 1997, respectively. Individuals were captured between June and October in water temperatures ranging from 15.4° to 28.5°C and salinities ranging from 22.8 to 30.3 ppt. Presence of neonates and catch per unit effort data indicate that pupping begins in late June near the southwestern coast of the Bay. Juveniles were present from early June through September and their spatial distribution in the Bay appeared uniform. Of 782 sandbar sharks tagged and released during the three years, 50 were recaptured. Mean distance from tag to recapture location and mean days-at-liberty of sandbar sharks recaptured in Delaware Bay during the year of tagging were 10km and 18 days, respectively. Some sharks were recaptured as far as 957km from the release location. Length distributions show young-of-the-year sandbar sharks grow about 2–3cm in length during the nursery season.     

Diel Movements of Bat Rays, Myliobatis californica, in Tomales Bay, California: Evidence for Behavioral Thermoregulation?

We used ultrasonic telemetry to examine movement patterns of 11 bat rays, Myliobatis californica, in Tomales Bay, California. Tomales Bay is long (20km) and narrow (1.4km), and is hydrographically separated into outer and inner bay regions. The outer bay (the outermost 8km) is characterized by oceanic conditions while the shallow inner bay (the innermost 12km) features wide seasonal temperature shifts. Five rays were tracked monthly from October 1990 to November 1991 and six rays (four of which carried temperature-sensing transmitters) were tracked daily from 30 June to 16 July 1992. Mean bat ray movement rate was 8.84mmin^–1 (range 4.49 to 13.40mmin^–1) and was not significantly affected by size (p=0.592), tidal stage (p=0.610), or time of day (p=0.327). Movement direction was unrelated to tidal stage (p=0.472) but showed a highly significant diel pattern (p<0.001). From 2:50–14:50h, rays moved toward the warmer and shallower inner bay, while from 14:50–2:50h they moved toward the cooler and deeper outer bay. These telemetry data, along with known bat ray foraging patterns and respiratory temperature-sensitivity, argue for behavioral thermoregulation as the primary influence on this movement pattern.     

Substrate Preferences of Juvenile Hatchery-reared Lake Sturgeon, Acipenser fulvescens

Substrate preferences of juvenile, hatchery-reared lake sturgeon, Acipenser fulvescens, from a Wisconsin population were examined relative to water temperature and velocity, fish size and time of day. Given the choice of a sand, gravel, rock or smooth plastic bottom, all sturgeon were strongly attracted to the sand substrate. Water temperature did not affect substrate preference, however small sturgeon (13.5cm mean FL) acclimated to 19°C were more active than those tested in 6°C water. Small sturgeon, under all conditions, were less sedentary in the early morning and late evening hours than during the daytime. Preference of small sturgeon for sand was slightly stronger when a current of 5cmsec^-1 was present. Substrate preference of larger sturgeon (24.3cm mean FL) was not affected by any of the parameters examined. In general, hatchery-reared lake sturgeon showed similar behaviors (with respect to substrate selection) as those previously described for the same population in the wild, making it possible that substrate preferences have a genetic component and likely that hatchery rearing does not alter instinctive behavior.     

Depth Distribution and Abundance of the Common Bully, Gobiomorphus cotidianus (Eleotridae), in Three Oligotrophic New Zealand Lakes, One of which is Turbid

The depth distribution of the common bully, Gobiomorphus cotidianus, a small benthic forage fish, was measured by trapping at set depths from 0–70m in three large oligotrophic lakes, including one where inorganic sediment from a glacially-fed river produces turbid conditions. Bullies occurred at all depths from 0.5–70m in the clear lakes, but none were present below 25m in the turbid lake. Two groups of bullies were present in the clear lakes; a high-density, littoral stock at depths of 0.5–25m, and a low-density, profundal stock at depths of 30–70m. These groups were further distinguished by differing buoyancy requirements and feeding habits. The swimbladders of littoral bullies contained gas, but those of the profundal bullies, which fed more than littoral bullies by both day and night, did not. The variation in mean CPUE with depth within the littoral zone was not related to water temperature, oxygen concentration, or conductivity. Nor was it related to a reduction in light levels or to reduced water transparency caused by increased turbidity. It may therefore be controlled by biotic factors. The absence of a profundal stock below the littoral zone in the turbid lake indicates that the settlement of fines from turbid inputs may affect bully abundance in deeper waters. As conventional measures of the abundance of benthic fish in lakes are often restricted to littoral habitats, and do not reflect changes in abundance with depth, an index of overall abundance based on depth distribution was developed to allow comparisons between lakes.     

Laboratory culture studies of Trichodesmium isolated from the Great Barrier Reef Lagoon, Australia

Cultures of Trichodesmium from the Northern and Southern Great Barrier Reef Lagoon (GBRL) have been established in enriched seawater and artificial seawater media. Some cultures have been maintained with active growth for over 6years. Actively growing cultures in an artificial seawater medium containing organic phosphorus (glycerophosphate) as the principal source of phosphorus have also been established. Key factors that contributed to the successful establishment of cultures were firstly, the seed samples were collected from depth, secondly, samples were thoroughly washed and thirdly, incubations were conducted under relatively low light intensities (PAR 40–50molquantam^–2s^–1). N₂ fixation rates of the cultured Trichodesmium were found to be similar to those measured in the GBRL. Specific growth rates of the cultures during the exponential growth phase in all enriched media were in the range 0.2–0.3day^–1 and growth during this phase was characterised by individual trichomes (filaments) or small aggregations of two to three trichomes. Characteristic bundle formation tended to occur following the exponential growth phase, which suggests that the bundle formation was induced by a lack of a necessary nutrient e.g. Fe. Results from some exploratory studies showed that filament-dominated cultures of Trichodesmium grew over a range of relatively low irradiances (PAR 5–120molquantam^–2s^–1) with the maximum growth occurring at 40–50molquantam^–2s^–1. These results suggest that filaments of the tested strain are well adapted for growth at depth in marine waters. Other studies showed that growth yields were dependent on salinity, with maximum growth occurring between 30 and 37psu. Also the cell yields decreased by an order of magnitude with the reduction of Fe additions from 450 to 45nM. No active growth was observed with the 4.5nM Fe addition.     

Proliferation and germination of somatic embryos from embryogenic suspension cultures in <Emphasis Type="Italic">Phœnix dactylifera</Emphasis>

The present study demonstrates a procedure for the rapid development of a high number of somatic embryos from embryogenic suspension culture. This method might be efficient for mass propagation of Phnix dactylifera L. Embryogenic callus placed in liquid medium with 10^–5M ABA yielded an average 72 embryos per 100ml of culture medium within 2months, while those placed on solid medium yielded an average of 33, 20 and 16 embryos per 100ml of culture medium respectively for 10^–7, 10^–6 and 10^–5 M ABA after 4months. The combination of 2,4-DIchlorophenoxyacetic acid (2,4-D) (4.5×10^–7M), glutamine (6.7×10^–4M), and ABA (10^–5M) (L8 liquid medium) showed a beneficial effect on somatic embryos production compared to 2,4-D and glutamine alone, while this combination significantly (p<0.05) increased the accumulation of storage proteins (144 and 138mgg^–1 DW respectively for Jihel and Bousthami noir cultivars) in somatic embryos. The somatic embryos which underwent maturation on medium containing only 4.5×10^–7M 2,4-D and 10^–5M ABA (L6 liquid medium) accumulated more sugars (292 and 265mgg^–1 DW respectively for Jihel and Bousthami noir) than those matured on any other liquid medium. Histological studies revealed that somatic embryos (developed in L6 and L8 liquid media) accumulated less reserve compounds (proteins and sugars) than zygotic embryos. The addition of activated charcoal (0.25 and 0.5gl^–1) and phytagel^® (2.5gl^–1) to the germination medium may be useful for enhancing the germination of Phnix dactyliferasomatic embryos.     

Preliminary Study of Vertebral Growth Rings in the Whale Shark, Rhincodon typus, from the East Coast of South Africa

Growth rings (GR) in vertebral centra of 15 whale sharks, Rhincodon typus, four female (418–750cm precaudal length), 10 male (422–770cm), and one of unknown sex (688cm), were examined using x-radiography. GR counts were made from scanned images and count precision was determined using the average percentage error index (4.19%) and the index of precision D (3.31%). In females, counts ranged from 19 GR (418cm) to 27 GR (750cm); in males from 20 GR (670cm) to 31 GR (770cm). Three mature males had 20 GR (670cm), 24 GR (744cm) and 27 GR (755cm). A female with 22 GR (445cm) was adolescent. There was a linear relationship between centrum dorsal diameter and body length, and back-calculated body lengths at number of GR are presented. A linear relationship between body length and number of GR prevented the calculation of von Bertalanffy parameters from either observed or back-calculated values.     

First investigation of ultraoligotrophic alpine Lake Puma Yumco in the pre-Himalayas,China

Lake Puma Yumco is a typical alpine lake (altitude 5030m) located in the pre-Himalayas of Tibet, China, and this study was the first limnological investigation ever conducted on it. Lake Puma Yumco (28°34N, 90°24E) has the following morphometric properties: maximum length 31km, maximum width 14km, mean width 9km, shoreline 90km, surface area 280km², and shoreline development 1.5. Transparency was approximately 10m, even in the thawing season. The extinction coefficient of the lake water was calculated as 0.15m^–1. Annual maximum transparency was estimated from the depth of the Chara zone to be 30m. Dissolved oxygen was 7mg O₂ l^–1 and showed saturated values, and salinity was 360mgl^–1. The chemical type of the lake water was Mg-Ca-HCO₃-SO₄, and it was slightly alkaline in character. Total nitrogenous nutrients (sum of ammonia, nitrite, nitrate, and urea nitrogen), phosphate, and silicate were extremely low at 1, 0.02, and 9µM, respectively. Dissolved organic carbon, nitrogen, and phosphorus concentrations were 160, 11, and 0.08µM and the molar ratio was calculated as 2100:140:1. Chlorophyll a concentration was 0.2mgm^–3. Phytoplankton and zooplankton were dominated by Aphanocapsa sp. and Diaptomidae. Both nitrogen and phosphorus appear to be the limiting parameters for phytoplankton growth. Organic carbon and nitrogen contents in lake sediments were low and the sediments contained a large amount of CaCO₃. The grain size of sediment was that of silt-sand in most cases. The present results indicate that the pre-Himalayan alpine freshwater Lake Puma Yumco is an ultraoligotrophic lake.     

Vertical planktonic structure in the central basin of Lake Baikal in summer 1999, with special reference to the microbial food web

Planktonic microbial interactions in the central basin of Lake Baikal were examined on a summer day in 1999. The subsurface maxima of bacterial abundance and chlorophyll concentration were recorded at the same depth, whereas the vertical distribution of heterotrophic nanoflagellates was the inverse of those of bacteria and picophytoplankton. Release of extracellular organic car-bon (EOC) from phytoplankton was estimated by the NaH¹⁴CO₃ method as 2.4µgCl^–1day^–1. Bacterial production (4.3µgCl^–1day^–1), estimated in a bottle incubation experiment using size-fractionated water samples, exceeded the EOC released. Thus, other supplying sources of organic matter are needed for the bacterial production. Grazing (2.6µgCl^–1day^–1) was also estimated in the experiment and accounted for 60% of the bacterial production. This is the first report on the microbial food web in the central basin of Lake Baikal.     

Fine root biomass,production and turnover in a fertilized <Emphasis Type="Italic">Larix leptolepis</Emphasis> plantation in central Korea

The effects of fertilization [control (C), 200kgNha^–1+25kgP ha^–1 (LNP) and 400kgNha^–1+ 50kgP ha^–1 (HNP)] on fine root dynamics were examined in a 40-year-old Larix leptolepis plantation in central Korea. The average fine root biomass during the growing season for C, LNP and HNP was 957, 934 and 814kgha^–1, respectively, whereas the fine root production for C, LNP and HNP was 2103, 2131 and 2066kgha^–1, respectively. Nitrogen and P inputs into the soil via fine root turnover for C, LNP and HNP were 23.0 and 1.2, 23.3 and 1.2 and 22.6 and 1.2kgha^–1, respectively. There were no significant differences in fine root biomass, production and N and P inputs through fine root turnover between the fertilization treatments during the first growing season after fertilization.     

Reproduction of the Endangered Killifish Aphanius iberus at Different Salinities

Adult fish of a freshwater population of the Iberian endangered cyprinodontid Aphanius iberus, were induced to reproduce at salinities of 5, 15, 30, 45 and 60ppt. For each salinity five 30l aquaria were used, each one including a male and two females. Maturity and spawning outside the natural season, were obtained at conditions of 22 to 28°C and a photoperiod of 14L:10D. The larvae were fed with rotifers Brachionus plicatilis and Synchaeta cecilia valentina. Experiment lasted 40 days. The first spawning occurred on the 17th day at 45ppt of salinity and the first embryos hatched on the 34th day at 5 and 15ppt salinity. The final average number of larvae per aquarium ranged from 5.2 (45ppt salinity) to 10.8 (15ppt salinity). No significant differences were found between the average values at different salinities (p<0.01).     

Evidence of downstream migration of Sakhalin taimen, <Emphasis Type="Italic">Hucho perryi</Emphasis>, as revealed by Sr : Ca ratios of otolith

The migratory history of Sakhalin taimen, Hucho perryi, was examined in terms of strontium (Sr) and calcium (Ca) uptake in the otolith by using wavelength dispersive X-ray spectrometry on an electron microprobe. Otolioth Sr:Ca ratios of freshwater-reared samples remained consistently at low levels throughout the otolith. The Sr:Ca ratios of samples from Lake Aynskoye of Sakhalin Island showed a low value from the core up to a point of 700–2140µm. Thereafter, the ratios increased sharply and remained at higher levels up to the outermost regions. The difference in Sr:Ca ratio might be the result of the presence of individuals that underwent seawater and freshwater life history phases, probably reflecting the ambient salinity or the seawater–freshwater gradient in Sr concentration. Otolith Sr:Ca ratio analysis revealed downstream migration history in H. perryi.     

Plant regeneration via somatic embryogenesis in Styrian pumpkin: cytological and biochemical investigations

Somatic embryo formation was induced from cotyledon explants of Styrian pumpkin (Cucurbita pepo L. subsp. pepo var. styriaca Greb.) by using a solid MS medium supplemented with 16.11M NAA and 4.44M BA or 26.85M NAA and 13.32M BA. The callus proliferation was more efficient on medium supplemented with 26.85M NAA and 13.32M BA. In contrast, the embryogenic response was higher on medium with lower concentrations of growth regulators (16.11M NAA and 4.44M BA). The time needed for embryo induction did not depend on medium composition. Embryos in globular stage were transferred to three different maturation media, containing 2.89M GA₃ in combination with 0.54M NAA, 11.42M IAA and growth regulator-free medium. The germination rate was the highest when embryos were cultured on medium with 11.42M IAA. Plantlets grown on this medium achieved maturity suitable for transplantation into soil within 9 to 10weeks. The regenerated plants were successfully transferred into field and developed fertile flowers and set fruits. Biochemical analysis showed significant lower total glutathione levels among in vitro grown plantlets compared to seedlings grown in soil. When the plantlets were transferred into soil, they reached a normal size within a month and the glutathione concentration was comparable to seed-derived plants at the same developmental stage. Transmission electron microscopy was used to investigate possible differences in the ultrastructure of cells from callus cultures, and leaf cells of regenerated and seed-derived plants. Differences in the ultrastructure were found within chloroplasts which contained only single thylakoids, large starch grains and small plastoglobuli in callus cells in comparison to leaf cells, which possessed a well developed thylakoid system, small starch grains and large plastoglobuli.     

Flexibility on the karyotype evolution in bitterlings (Pisces, Cyprinidae)

In bitterlings (Acheilognathinae) C- and Ag-banding karyotypes of 6 species-subspecies collected in China and South Korea were analyzed. The chromosomal constitution of 2n=46 (4SM+42ST) in Rhodeus atremius fangi was quite different from that of 2n=48 (8M+20SM+20ST) in other species-subspecies in Rhodeus. It was concluded from the analysis of banded chromosomes that the increase in number of ST during the karyotype change from 2n=48 to 2n=46 was achieved by a series of pericentric inversions from 24 M-SM to 24 ST, and the decrease in the diploid number was caused by an additional tandem fusion of 4 ST chromosomes, forming a new ST pair in the 2n=46 karyotype. The karyotype of Tanakia koreensis, T. signifer, and Acheilognathus macropterus is 2n=48 (8M+20SM+20ST), 2n=48 (8M+20SM+14–16ST+4–6 A), 2n=44 (14M+16SM+14ST), respectively. In R. ocellatus ocellatus, T. koreensis, T. signifer and A. macropterus, karyotype changes from 2n=48 to 2n=44 due to centric fusion and inversion have also been estimated. It was suggested that C-banding heterochromatin was greatly concerned with the karyotype evolution in bitterlings.     

Mode of uptake of sterol by Arthrobacter simplex

The mechanism of uptake of water-insoluble -sitosterol by a newly isolated strain of Arthrobacter simplex SS-7 was studied. The production of an extracellular sterol-pseudosolubilizing protein during growth of A. simplex on -sitosterol was demonstrated by isolating the factor from the cell-free supernatant and its subsequent purification by Sephadex G-150 column chromatography. The M _r of the purified sterol-pseudosolubilizing protein determined by SDS–PAGE was 19kDa. The rate of sterol pseudosolubilization (5.2×10^–3g l^–1h^–1) could not adequately account for the rate of sterol uptake (72×10^–3g l^–1h^–1) and the specific growth rate (56×10^–3 h^–1). However in the unfavourable growth condition, when the cells were treated with sodium azide at the level of 30–60% of MIC, the sterol pseudosolubilization accounted for nearly 74% of the total growth containing 96% free cells. Cellular adherence to substrate particles was found to play an active role in the normal growth of the strain on -sitosterol. Unlike sodium acetate-grown cells, whose surface activity was negligible (60mNm^–1), the sterol-grown cells had strong surface activity (40mNm^–1). The high lipid content and long chain fatty acids in the cell-wall of -sitosterol-grown cells probably contribute to the high sterol adherence activity of the cells.     

(T2AG3)n Telomeric Sequence Hybridization Indicating Centric Fusion Rearrangements in the Karyotype of the Rodent Oryzomys Subflavus

Chromosome preparations of 30 specimens of Oryzomys subflavus trapped in eight Brazilian localities were C-, and G-banded and analyzed by fluorescence in situ hybridization (FISH). Two karyotypes were found, 2n=50/FN=64, at three coastal localities of the Atlantic Forest domain, and 2n=58/FN=70 at two sites located in the Cerrado biome, Brazil Central. Two fluorescence in situ hybridization (FISH) patterns of the telomeric sequence (T₂AG₃)_n were observed: in both karyotypes the probes hybridized to the telomeres of all chromosomes and also a hybridization signal in the centromeric regions of two autosome pairs was seen in the 2n=50 karyotype. These results, together with the occurrence of other diploid numbers described in the literature, suggest that O. subflavus is a complex species, bearing fusion/fission rearrangements proper to the different biomes which it inhabits.     

Macronutrient input from pollen in two regenerating pine stands in southeast Korea

This study examined macronutrient input from pollen in two naturally regenerating pine stands in southeast Korea. Durham gravity pollen collectors were used to measure pine pollen deposition and the macronutrients in the collected pine pollen were analyzed. In 1998, pine pollen deposition began just before 18 April and lasted for approximately 2weeks. Total pine pollen deposition differed between the two sampling sites; 27.5kgha^–1 was collected from the mature stand and 17.7kgha^–1 was collected from the young stand. The values for nutrient deposition from pine pollen are 549gha^–1 N, 78gha^–1 P, 240gha^–1 K, 45gha^–1 S and 22gha^–1 Mg at the mature stand and 353gha^–1 N, 51gha^–1 P, 151gha^–1 K, 27gha^–1 S and 14gha^–1 Mg at the young stand, suggesting that nutrients from pine pollen contribute to forest nutrient cycling. The pine pollen deposition values obtained from our study (17.7–27.5kg^–1ha^–1year^–1) are approximately 1/115–180-fold that of pine litterfall in Korea. If we take pollen nutrients into account, the contribution rate of pollen to the annual nutrient input is very high in our study (N 1/30, P 1/5, K 1/9 that of litterfall). Macronutrient deposition from pine pollen is concentrated temporally in spring. Although the annual contribution of nutrient mass by pollen is small compared to that of litterfall, the rapid turnover rate of pollen nutrients combined with episodic deposition suggests that pollen may play a disproportionate role in temperate pine forest nutrient cycling.     

Biological productivity of Lake Towada,a north temperate,oligotrophic, kokanee fishery lake

During the Lake Towada survey from April through October 1998, we measured primary production at shore and offshore stations, and calculated crustacean zooplankton production from samples collected at the offshore station. We then analyzed these data and compared them with commercial fishery data in order to discuss the energy flow in this lake where kokanee (Oncorhynchus nerka) fisheries are one of the main businesses. At all stations, primary production was relatively high: 150–300mgCm^–2day^–1 in April–mid-June and lower at ca. 100mgCm^–2day^–1 thereafter. The variation in primary productivity could largely be explained by multiple regression models that included phytoplankton biomass and ambient nutrient conditions as independent variables. Among zooplankton, rotifers had their peak abundance in May, before the crustacean zooplankton (Daphnia longispina, Bosmina longirostris, and Acanthodiaptomus pacificus) population was well established. D. longispina dominated the crustacean zooplankton community in terms of biomass and production; their production during the study period made up 80% of crustacean community production (19.6gdry-wtm^–2), which was 40% of primary production during the survey. In July, when the abundance of D. longispina was particularly high, their daily production slightly exceeded daily primary production, which resulted in ca. 30% and 75% reduction in the amount of particulate organic carbon and chlorophyll a, respectively, during this period. The community ingestion rate of crustacean zooplankton, calculated from their daily production (D. longispina accounted for 90%) and the assumption that their gross production efficiency (K₁) was 60%, could roughly explain this reduction of particulate matter, corroborating previous studies that the grazing of D. longispina can significantly improve the water transparency of this lake. The catch of kokanee and pond smelt (Hypomesus transpacificus nipponensis, another important fish in the lake) during the survey corresponded to 1.1% of crustacean community production, and corresponded to 0.45% of the primary production, which is one of the highest recorded values. Bearing in mind that D. longispina was the major food item of planktivorous fish such as kokanee and pond smelt, the present study suggests that the energy transfer from phytoplankton to zooplankton to fish is outstandingly efficient, compared with other aquatic ecosystems, when D. longispina dominates in the lake.     

Effects of climate on the radial growth of tree species in the upper and lower distribution limits of an altitudinal ecotone on Mount Norikura,central Japan

Tree-ring width chronologies were developed for Abies veitchii, Betula ermanii and Betula platyphylla var. japonica in their altitudinal ecotone (approximately 1600m a.s.l.) on Mount Norikura, central Japan, to determine what climatic conditions affect the growth of tree species in the upper and lower distribution limits of an altitudinal ecotone. This altitude was the lower distribution limit for A.veitchii and B.ermanii in the subalpine zone, and was the upper distribution limit for B.platyphylla var. japonica in the montane zone on Mount Norikura. Tree-ring widths of the two Betula species and A.veitchii were positively correlated with the August precipitation of the current and previous years, respectively. Precipitation in August (the hottest month) was reduced compared with other months during summer. Tree-ring width of B.platyphylla var. japonica showed no correlation with temperatures in any month in its upper distribution limit. In contrast, tree-ring widths of B.ermanii and A.veitchii were negatively correlated with the August temperatures of the current and previous years, respectively, at the lower distribution limit of these species. Therefore, the two Betula species and A.veitchii responded to climatic conditions of the current and previous years, respectively. The present study also suggests that a water deficit in August reduces growth of these three species in this altitudinal ecotone, irrespective of the upper or lower distribution limits, and that a high August temperature is more detrimental to the growth of A.veitchii and B.ermanii in their lower distribution limits. Thus, the three species with different altitudinal distributions examined in the present study responded differently to climatic conditions in this altitudinal ecotone on Mount Norikura.