Vertical vegetation zones along 30° N latitude in humid East Asia

Structural changes in altitudinal vegetation zones along a 30° N parallel were studied based on vegetation data from 20 mountains in East Asia, from 85° E to 130° E longitude. The altitude of comparable vegetation zones showed a sharp increase of 1400–1900 m from east to west. Forest limit reached an altitude of 4400–4600 m in the eastern Tibetan Plateau, being the highest forest limit in the world. The limidng factor for the upper limit of a vegetation zone was different in the east and west. Low temperature in winter controlled the upward distribution of the evergreen broadleaf forest in the east, whereas the limiting factor was growing season warmth in the west. A close correlation was found between the climatic indices and annual range of monthly mean temperature (ART) at the upper limit of a vegetation zone.Component genera of each vegetation zone along the 30° N parallel were analyzed, and it was found that the alternation of component genera from east to west was much more apparent in cool-temperate forests, reflecting their response to macrotopography and air masses. The distribution of Fagus extended into winter-cold regions, whilst Tsuga occurred principally in oceanic and warm climates. The northern limit of Tsuga corresponded well to an ART isotherm of 23 °C and its southern limit coincided with that of Fagus. According to the distribution of Fagus and Tsuga, the cool-temperate forests in East Asia along the 30° N belt were divided into three types: deciduous broadleaf forest (represented by Fagus), mixed forest (dominated by Fagus, Tsuga and others), and mixed evergreen forest (consisting mainly of Tsuga and sclerophyll oaks).     

Late-quaternary shift offagus distribution

Based on six resolved maps of its pollen frequency (dating 13,000, 10,000, 8,000, 6,000, 3,000 and 500 yr B.P.) at 33 sites scattered almost throughout the Japanese Archipelago,Fagus shows principally a, unidirectional late-Quaternary shift in distribution from the southwest to the northeast. The maximum areal coverage was from 10,000 to 7,000 years ago, although northeastern populations were not fully developed by this time. The northern limit ofF. crenata, which has virtually not changed in the past 7,000 years, was probably regulated by total precipitation during the growing season from April to October (called the effective precipitation). ForF. crenata to migrate farther north in Hokkaido under the modern temperature regime, a minimum of 800 mm of precipitation, evenly distributed over this period, is required.     

The role of human disturbance in the local Late Holocene establishment of Fagus and Picea forests at Flahult, Western Småland, Southern Sweden

A pollen record from a small alder carr located in the centre of aFagus stand near the hamlet of Flahult in southern Småland has shown thatFagus became established in a semi open cultural landscape about 900 B.P. Human disturbance seems to have controlled the local establishment ofFagus at this site through an expansion of pastoral farming. TheFagus dominance in the present stand seems to be of recent origin, asFagus pollen percentages and influx values have increased considerably only during the last 50 years. The modern composition and structure of theFagus stand are probably an effect of changes in land-use and decreased human activity at the end of the last century. Today, only occasionalPicea individuals occur in the studied stand, andPicea does not appear to have been more abundant in the recent past. The regional expansion ofPicea has probably occurred during this century and has been favoured by modern forestry during the last 50 years.     

Determinants of woody species richness in Scot pine and beech forests: climate, forest patch size and forest structure

We analysed patterns of woody species richness in Pinus sylvestris and Fagus sylvatica forests in Catalonia (NE Spain) from forestry inventory databank in relation to climate and landscape structure. Both types of forests are found within the same climatic range, although they have been managed following somewhat different goals. Overall, woody species richness significantly increased when conditions get closer to the Mediterranean ones, with milder temperatures. Differences between the two types of forests arose when comparing the relationship between richness and forest patch size. Woody species richness increased in pine forests with patch size, while the opposite trend was observed in beech forests. This pattern is explained by the different behaviour of structural canopy properties, since leaf area index and canopy cover showed a steeper increase with increasing forest patch size in Fagus forests than in Pinus ones. Accordingly, richness decreased with canopy cover in Fagus plots, but not in Pinus ones. We suggest that these differences would be related to management history, which may have enhanced the preservation of beech stands in larger forest landscape units.     

Post-glacial changes in spatial patterns of vegetation across southern New England

Aim We analysed lake‐sediment pollen records from eight sites in southern New England to address: (1) regional variation in ecological responses to post‐glacial climatic changes, (2) landscape‐scale vegetational heterogeneity at different times in the past, and (3) environmental and ecological controls on spatial patterns of vegetation. Location The eight study sites are located in southern New England in the states of Massachusetts and Connecticut. The sites span a climatic and vegetational gradient from the lowland areas of eastern Massachusetts and Connecticut to the uplands of north‐central and western Massachusetts. Tsuga canadensis and Fagus grandifolia are abundant in the upland area, while Quercus, Carya and Pinus species have higher abundances in the lowlands. Methods We collected sediment cores from three lakes in eastern and north‐central Massachusetts (Berry East, Blood and Little Royalston Ponds). Pollen records from those sites were compared with previously published pollen data from five other sites. Multivariate data analysis (non‐metric multi‐dimensional scaling) was used to compare the pollen spectra of these sites through time. Results Our analyses revealed a sequence of vegetational responses to climate changes occurring across southern New England during the past 14,000 calibrated radiocarbon years before present (cal yr bp ). Pollen assemblages at all sites were dominated by Picea and Pinus banksiana between 14,000 and 11,500 cal yr bp ; by Pinus strobus from 11,500 to 10,500 cal yr bp ; and by P. strobus and Tsuga between 10,500 and 9500 cal yr bp . At 9500–8000 cal yr bp , however, vegetation composition began to differentiate between lowland and upland sites. Lowland sites had higher percentages of Quercus pollen, whereas Tsuga abundance was higher at the upland sites. This spatial heterogeneity strengthened between 8000 and 5500 cal yr bp , when Fagus became abundant in the uplands and Quercus pollen percentages increased further in the lowland records. The differentiation of upland and lowland vegetation zones remained strong during the mid‐Holocene Tsuga decline (5500–3500 cal yr bp ), but the pattern weakened during the late‐Holocene (3500–300 cal yr bp ) and European‐settlement intervals. Within‐group similarity declined in response to the uneven late‐Holocene expansion of Castanea, while between‐group similarity increased due to homogenization of the regional vegetation by forest clearance and ongoing disturbances. Main conclusions The regional gradient of vegetation composition across southern New England was first established between 9500 and 8000 cal yr bp . The spatial heterogeneity of the vegetation may have arisen at that time in response to the development or strengthening of the regional climatic gradient. Alternatively, the differentiation of upland and lowland vegetation types may have occurred as the climate ameliorated and an increasing number of species arrived in the region, arranging themselves in progressively more complex vegetation patterns across relatively stationary environmental gradients. The emergence of a regional vegetational gradient in southern New England may be a manifestation of the increasing number of species and more finely divided resource gradient.     

Geographic Distribution of Human Blastomycosis Cases in Milwaukee, Wisconsin, USA: Association with Urban Watersheds

Most studies of endemic blastomycosis and outbreaks have involved rural areas. Case homesites in rural Northern Wisconsin have been associated with waterways and sand soils. ARC-GIS was used to geocode addresses and to observe geographic features of homesites from 45 State-mandated reports of human blastomycosis in urban Milwaukee County, Southeastern Wisconsin 2000–2004. Each case property was directly observed, and houses and duplexes (N = 38) were compared with 151 same-street control homesites. Categorical data was analyzed using a chi-square or Fisher’s exact test; continuous variables by Kruskal–Wallis test. One case cluster was seen on Milwaukee’s North side where the estimated annual incidence was 2.8/100,000 compared to 0.96/100,000 for the entire county. Cases were less common in the most urbanized watersheds (0.49/100,000/yr) versus Lake Michigan shores (0.85) versus remaining three open watersheds (1.4) [P<0.01]. Case homesites averaged 1067 m to waterways and none were on sand soils. (Comparison is made to a Northern Wisconsin community where case homesites averaged 354 m to waterways, 24/25 were on sand soils and annual incidence was 74/100,000.) No unique features of case homesites were identified in Milwaukee County. In this urban area of Wisconsin, relatively low incidence rates may be explained, in part, by lower density of inland waterways and lack of sand soils, however, blastomycosis cases appear to be associated with open watersheds.     

Plumatella nitens, a new species of freshwater bryozoan from North America (Ectoprocta: Phylactolaemata), previously misidentified

Plumatella nitens is a newly recognized species of phylactolaemate bryozoan in North America. It has previously been combined with either P. repens or P. fungosa, from which it differs primarily by the floatoblast. In P. nitens the ventral floatoblast annulus is uniformly narrow with no significant widening at the poles. The dorsal floatoblast fenestra is conspicuously larger than in either P. repens or P. fungosa. Reticulated ridges on the dorsal fenestra are weak along the margins, becoming unusually prominent in the center. The sessoblast is densely covered with uneven papillae. Spotty sampling so far shows a distribution only in the northern half of North America, including Massachusetts, Michigan, Minnesota, Wisconsin, Ontario, and the northern regions of Illinois, Indiana, and Ohio.     

Some problems of forest transformation at the transition to the oligocratic/<Emphasis Type="Italic">Homo sapiens</Emphasis> phase of the Holocene interglacial in northern lowlands of central Europe

The paper discusses the main changes in the composition of mixed deciduous forests which occurred mostly between 5,000 and 2,000 b.p., based on selected pollen diagrams from the lowlands of Germany, Denmark and Poland, and including two pollen diagrams from varved sediments, used as reference sites, and on isopollen maps for Poland. The Ulmus retreat is shown on maps, and additional data for its pathogenic origin are presented. Corylus declines at ca. 3,500 b.p. at both reference sites, and its connection with Fagus expansion in the west and Carpinus expansion in the east is discussed. The nature of post-Atlantic transitory shrub–forest communities with dominant Corylus and Quercus is presented. Relationships between the history of Fagus and Carpinus and the development of human settlements are shown. Human impact has been admitted as one of the most important driving forces determining vegetational development since the time of fully developed Neolithic cultures. Other very important abiotic factors were the climate (particularly after 2,500 b.p.), and soil degradation.     

The relationship between fecundity and adult body weight in Homeotherms

Summary Bythotrephes cederstroemii Schoedler, a predatory freshwater zooplankter (Crustacea: Cladocera), was first found in the Laurentian Great Lakes in December 1984. The first individuals were from Lake Huron, followed in 1985 with records from Lakes Erie and Ontario. By late August, 1986 the species had spread to southern Lake Michigan (43°N). Bythotrephes has not previously been reported from North America, but has been restricted to a northern and central Palearctic distribution. Its dramatic and widespread rise in abundance in Lake Michigan was greatest in offshore regions. Bythotrephes appears to be invading aggressively, but avoiding habitats presently occupied by glacio-marine relict species that became established in deep oligotrophic North American lakes after the Wisconsin glaciation. Because it is a voracious predator its invasion may lead to alterations in the native zooplankton fauna of the Great Lakes. It offers the chance to study how invading plankton species join an existing community. Judging from its persistence and success in deep European lakes, Bythotrephes may now become a permanent member of zooplankton communities in the Nearctic.     

Spread of the pinewood nematode vectored by the Japanese pine sawyer: modeling and analytical approaches

The pinewood nematode, Bursaphelenchus xylophilus, is the causative agent of pine wilt of Pinus thunbergii and P. densiflora in Japan. The nematode is vectored by cerambycid beetles of the genus Monochamus. It is inferred to have been introduced from North America early in the 1900s and then to have distributed in China, Korea, and Taiwan. Intensive and/or long-term studies of pine wilt systems have elucidated the pattern and mechanism of the nematode’s spread within a pine stand, dispersal of vector beetles, and spread pattern of pine wilt within a prefecture. The modeling of nematode spread over pine stands, which involves beetle reproduction within a pine stand, has been developing and should elucidate the factors influencing the rate at which the nematode range expands. In this review, we summarize the biologies of the nematode, beetle, and tree, and then characterize the spread of the nematode within a pine stand, locally over pine stands, and regionally over unit administrative districts. Local and regional spreading of the nematode is related primarily to long-distance dispersal by insect vectors and to the artificial transportation of pine logs infested with the nematode and its vector, respectively.     

The spring development of phytoplankton in Lake Erken: species composition,biomass, primary production and nutrient conditions — a review

Relative abundance and within-lake distributions of three fishes, northern redbelly dace (Phoxinus eos), finescale dace (Phoxinus neogaeus), and central mudminnow (Umbra limi), were examined using minnow traps in Tuesday Lake, a small bog lake in the Upper Peninsula, Michigan. For these species, catches in minnow traps placed at the perimeter of the lake were 21 to 52 times higher than catches in midlake traps. Variance: mean ratios of perimeter trap catches indicated that both dace species were highly aggregated while the distribution of mudminnows was less aggregated or random. Over an 11 day period during which all fish caught were removed from the lake, catch per unit effort (CPUE) of both dace species declined in response to fish removal. In contrast, CPUE for mudminnows was low initially, increased to an asymptote and then declined only in the last 5 days of the fish removal. The patterns of CPUE for mudminnows indicated that mudminnow trapability and/or activity was reduced in the presence of high densities of dace. The low abundance of dace in traps with many mudminnows suggested mudminnows avoided traps already containing dace. Throughout the removal period, CPUE provided an accurate index of dace abundance, whereas this was true for mudmnnows only after dace populations had been reduced drastically. Therefore, in any use of minnow traps to estimate populations, both spatial distributions and relative species abundance of small fishes must be taken into account.     

The dynamics of old-growth Pseudotsuga forests in the western Cascade Range,Oregon, USA

Size and age structure, spatial analysis, and disturbance history were used to analyse the population structures and regeneration patterns of 8 conifer stands in the central western Cascade Range, Oregon, USA. Variation in forest structure reflected the effects of frequent (20–50 yr) low-intensity fires and treefalls, infrequent (100–200 yr) localised, intense fires, and extensive fires that resulted in stand replacement (every ca 400 yr?).The amount of canopy removed and the size of openings formed by fires and treefalls were important determinants of subsequent forest establishment. Single or several species stands of Pseudotsuga and/or Abies procera, or mixed species stands of Pseudotsuga, Abies procera, Tsuga heterophylla and Abies amabilis established in openings where intense fires had removed most of the canopy trees over several ha. Multi-tiered and multi-aged stands, often containing 400–500 yr-old Pseudotsuga and variously-sized more or less even-aged patches of younger shade tolerant Tsuga heterophylla and/or Abies amabilis, occurred where lower-intensity fires did not kill all overstorey trees or where treefalls occurred after the initial fire.Current regeneration processes are influenced by overstorey composition, the availability and size of canopy openings, and the availability of substrates suitable for regeneration. Tsuga heterophylla and Abies amabilis established under Pseudotsuga menziesii and Abies procera canopies and in small canopy openings (<400 m²) created by windfalls, but rarely under Tsuga. Down logs and stumps were favoured establishment sites for Tsuga.The disturbance regime of fires of low-to moderate-intensity, windfalls, and occasional fires that result in extensive stand replacement contrasts with the pattern of infrequent, catastrophic disturbances proposed for other areas of the Pacific Northwest. Although fires at stand establishment commonly determine much of the composition, structure, and subsequent stand development, canopy replacement by shade tolerant species occurs as the different life histories of the species are expressed in response to various disturbances differing in intensity and frequency. Such a non-equilibrium view of vegetation change is consistent with many other fire-dominated forests of the western United States.     

Tsuga shimokawaensis,a new species of permineralized conifer leaves from the Middle Miocene Shimokawa Group,Hokkaido, Japan

Silicified pinaceous leaves from the late Middle Miocene bed of Shimokawa Town, central Hokkaido, Japan are described asTsuga shimokawaensis sp. nov. Comparisons with leaves of extant species ofTsuga show that the new species is assigned to sect.Tsuga, resembling the extant speciesT. heterophylla in having usually one-cell-layered hypodermis, andT. sieboldii in having mesophyll cells between the resin canal and the hypodermis. From cladistic analyses we infer thatTsuga shimokawaensis is positioned the basal in sect.Tsuga and that sect.Tsuga comprises four species groups.     

Aerobiology of Fagaceae pollen in Trieste (NE Italy)

The aerobiological behaviour of Fagaceae in Trieste and the correlations with the meteorological parameters were examined. Airborne pollen grains of Castanea, Fagus and Quercus were collected from 1990 to 2003 using a Hirst type spore trap. The main pollen season (MPS) takes place in April and May for Quercus and Fagus, in June and July for Castanea. The highest values occur in year 1993 for Quercus, in 1998 for Castanea and in 1992 for Fagus. The Fagaceae content of the air is mainly due to Quercus and Castanea pollen, Fagus usually having a scarce pollen shedding in Trieste. The highest counts of Fagaceae pollen grains are found from late April to mid May and are mainly due to the pollen shedding of oaks. The cumulative counts vary over the years, with a mean value of 2.719 pollen grains, a lowest total of 1.341 in 2002 and a highest total of 4.704 in 1993. No positive nor negative long-term trends in pollen shedding are found. No cyclic variations were observed. Spearman’s correlation was used to establish the relationship between the daily pollen counts and the daily meteorological data. Daily pollen concentrations present sometimes positive correlation with temperature, negative with rainfall and wind speed, and no correlation with humidity. Fagus and Quercus start dates result positively correlated between themselves. Significant correlations are found between the start of MPS and the mean and maximum temperature in March for Fagus and Quercus, and May for Castanea.     

The rapid spread of rusty crayfish (Orconectes rusticus) with observations on native crayfish declines in Wisconsin (U.S.A.) over the past 130 years

The rusty crayfish, Orconectes rusticus, is one of America’s best-known non-indigenous crayfishes, having been identified as extirpating native crayfishes and disrupting local aquatic ecosystems. Over the past 40–50 years, rusty crayfish have spread from its historical range in the Ohio River drainage (U.S.A.), to waters throughout much of Illinois, Michigan, Wisconsin, and Minnesota and parts of 11 other states, Ontario (Canada) and the Laurentian Great Lakes. Using a comprehensive dataset based on all known historical records and extensive present-day surveys (n = 2775) this study reports on the invasion history of rusty crayfish, with observations on concomitant declines of native crayfishes in Wisconsin over the past 130 years (1870–2004). We found that rusty crayfish occurrences have increased from 7% of all crayfish records collected during the first 20 years of their invasion (1965–1984) to 36% of all records during the last 20 years, and that rusty crayfish have replaced the northern clearwater crayfish (O. propinquus) and virile crayfish (O. virilis) as the most dominant member of the contemporary crayfish fauna. In light of our results we discuss the introduction, establishment and integration phases of the rusty crayfish invasion and provide preliminary predictions of the potential distribution of rusty crayfish in Wisconsin lakes based on critical environmental requirements.     

Effect of bryophytes on survival of conifer seedlings in subalpine forests of central Japan

Bryophytes form the major seedbed for coniferous trees in the subalpine forests of central Japan. Field experiments were conducted on the floor of a closed stand dominated byTsuga on Mt Fuji to examine the seedling survival ofAbies veitchii andTsuga diversifolia in seven substrate types in relation to the morphological characteristics of the seeds and seedlings. NeitherAbies norTsuga seedlings could survive on dwarf-bamboo litter beyond 2 years after the seed rain.Abies seedlings survived not only in all types of bryophyte communities but also in larch litter. In contrast, the survival ofTsuga seedlings was restricted to communities of smaller-statured bryophytes found on logs. The seeds and 1st year seedlings ofA. veitchii were larger than those ofT. diversifolia. Abies seedlings produced hypocotyls taller than any bryophyte community and radicles which were long enough to penetrate into the moist humus layer, whereasTsuga seedling radicles presumably penetrate into humus only in bryophyte communities forming a thin mat on logs. The effect of bryophytes on survival of tree seedlings therefore depends on the relationships between the morphology of seeds and seedlings and the structure of bryophyte communities.     

Spatial genetic structure and restricted gene flow in a functionally dioecious fig, <Emphasis Type="Italic">Ficus pumila</Emphasis> L. var. <Emphasis Type="Italic">pumila</Emphasis> (Moraceae)

The mutualism between fig plants and fig wasps has been recognized as one of the most specialized systems of symbiosis. Figs are pollinated by their highly specific pollinating fig wasps, and the pollinating fig wasps are raised within the syconia of figs. Recent studies indicated a difference between monoecious and dioecious figs in the dispersal range of pollinating wasps, which has potential consequences for gene flow. In this study, we detected the gene-flow pattern of the dioecious climbing fig, Ficus pumila L. var. pumila, at both local and regional scales. At the local scale, spatial autocorrelation analysis indicated strong genetic structure at short distances, a pattern of limited gene flow. This result was also supported by a high inbreeding coefficient (F _IS = 0.287) and significant substructuring (F _ST = 0.060; P < 0.001). Further analysis indicated that the effective gene dispersal range was 1,211 m, and the relative contribution of seed dispersal was smaller than that of pollen dispersal. The inferred effective range of pollen dispersal ranged from 989 to 1,712 m, while the effective seed dispersal range was less than 989 m. Lack of long-distance dispersal agents may explain the limited seed dispersal. The high density of receptive fig trees was the most likely explanation for limited pollen dispersal, and the position of syconia and relatively low wind speed beneath the canopy may contribute to this phenomenon. At the regional scale, significant negative correlations (kinship coefficient F _ij ranging from −0.038 to −0.071) existed in all comparisons between the studied population and other populations, and the assignment test grouped almost all individuals of the studied population into a distinct cluster. Asynchronous flowering on the regional scale, which provides a barrier for the pollinating wasps to fly from the studied population to the other populations, is probably responsible for the limited gene flow on the regional scale.     

Intercontinental dispersal: The origin of the widespread South American plant speciesGilia laciniata (Polemoniaceae) from a rare California and Oregon coastal endemic

Although separated by 7000-km,Gilia millefoliata, a rare annual plant from California and Oregon coastal dunes andG. valdiviensis, a rare Chilean coastal endemic are morphologically and ecologically quite similar. Their disjunct distribution was proposed to result from recent, birdmediated, intercontinental long-distance dispersal. Both species are morphologically similar to the abundant and ecologically diverse South American taxonG. laciniata. The relationship among these three taxa was investigated using DNA sequence from the nuclear ribosomal (ITS) and chloroplasttrnL regions, as well as isozyme and morphological variation to determine the roles of long-distance dispersal and ecological adaptation in the evolution of the group. These data suggest that aG. millefoliata-like ancestor underwent long-distance dispersal to South America, and there gave rise to the narrow endemicG. valdiviensis and the widespreadG. laciniata.     

Decline of a sylvatic focus of Schistosoma mansoni in Guadeloupe (French West Indies) following the competitive displacement of the snail host Biomphalaria glabrata by Ampullaria glauca

Summary Grand Etang lake in Guadeloupe is a focus of intestinal schistosomiasis characterized by the virtual absence of human contact and the presence of a heavily infested rat population. The lake, with a surface area of 0.03 km², is situated in rain forest at an altitude of 450 m. Originally it contained an extensive belt of the floating plant Pistia stratiotes which provided a favourable habitat for Biomphalaria glabrata, the intermediate host snail of Schistosoma mansoni. In 1974 and 1975, a low prevalence (about 3%) of S. mansoni was observed in B. glabrata while a high prevalence (about 60%) was recorded in rats. The rat population was infected with another trematode, Ribeiroia guadeloupensis, which requires two intermediate hosts, B. glabrata and the fish Tilapia mossambica. In 1976, the prosobranch snail, Ampullaria glauca, was accidentally introduced into the lake. By 1980, this snail had spread over half of the lake and had caused marked regression of the P. stratiotes layer. Concomitantly, the population of B. glabrata declined to such a point that in 1985 only a small colony remained in the northern section of the lake. The consequences of these changes are reflected in a rapid decline of S. mansoni in the rat population from 61.3% in 1980 to 34.8% in 1981, 6.5% in 1982, 2.8% in 1983, 11.6% in 1984, and 0% in 1985 and 1986.     

Effects of red pine (Pinus resinosa Ait.) mycorrhizoplane-associated actinomycetes onin vitro growth of ectomycorrhizal fungi

Mycorrhizoplane-associated actinomycetes were isolated using an enrichment technique from red pine (Pinus resinosa Ait.) roots of seedlings recently outplanted onto cleared northern hardwood sites in the Upper Peninsula of Michigan, USA. Interactions were assessedin vitro between actinomycete isolates and three commonly occurring ectomycorrhizal fungi (Laccaria bicolor (Maire) Orton,L. laccata (Scop.: Fr.) Berk. and Br., andThelephora terrestris Fr.). Most actinomycete isolates exerted a range of effects on the growth of the three fungus isolates during the four week test period, inhibiting some while stimulating others; several inhibited growth of all three fungus isolates. Mycorrhizoplane-associated actinomycetes show potential for use as coinoculants with selected ectomycorrhizal fungi to optimize the soil microflora for developing seedlings.