Ophiostomatoid fungi associated with bark beetles onAbies veitchii in wave-regenerated forests

Relationships between tree mortality and bark beetle infestation onAbies veitchii at the wave-regenerated forest in Mt. Asahi, Okuchichibu area were investigated. Most of the firs with green needles and newly developed current year’s shoots in the dieback zone were heavily infested by bark beetles before the death of the trees. After heavy infestation of beetles, about half of the infested firs died within the year, and the other half died in the next year. When the species composition of bark beetles and associated ophiostomatoid fungi were investigated in Mt. Asahi and also at a typical wave-regenerated forest in Mt. Shimagare, Yatsugatake area,Cryphalus montanus andC. piceae were dominant beetle species for Mt. Asahi and Mt. Shimagare, respectively.Ophiostoma subalpinum andO. europhioides were dominant fungal species at both wave-generated forests. BecauseO. subalpinum was detected more frequently from deeper areas of sapwood thanO. europhioides, it was suggested that the fungal species may accelerate the death of stressed firs in wave-regenerated forests. Contribution No. 169, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Water relations of Yezo spruce and Todo fir in declined stands of boreal Forest in Hokkaido, Japan

Recently, symptoms of decline have been widely observed in Yezo spruce (Picea jezoensis) and Todo fir (Abies sachalinensis) in Hokkaido. In order to clarify the mechanism of decline, the water status of Yezo spruce and Todo fir trees in the Tokyo University Forest in Hokkaido were investigated. The decline is observed mainly in stands damaged by Typhoon XV of 1981 (D-stands), but is not observed in undamaged stands (C-stands). Sampled trees in both types of stands were selected, the severity of their decline estimated, diurnal water potentials measured and water relation parameters such as water potential at turgor-loss point ( ) and osmotic potential at full saturation ( ) were estimated by pressure-volume analysis. The diurnal trends of leaf water potential and midday water potential ( ) of the sample trees were clearly different between the D-stands and the C-stand. Water stress in trees was much more severe in the D-stands than in the C-stand. and of the declining trees were lower in the D-stands than in the C-stand. However, and were not significantly different between declining trees and healthy-looking trees in D-stands. It was concluded that stand-level water stress, induced by the destruction of the canopy by the typhoon, was associated with the decline symptoms. The measurement of water relation parameters proved to be useful for diagnosis and prediction of decline at a stand level in this area.     

Effect of seed source elevation on bud opening of Yezo spruce (<Emphasis Type="Italic">Picea jezoensis</Emphasis>)

Spring frost damage is one of the obstacles to be overcome in establishing a Yezo spruce (Picea jezoensis Carr.) plantation. The timing of bud opening of Yezo spruce seedlings cultured from seeds collected at three different elevations (420, 700, and 1200m) in the Tokyo University Forest in Hokkaido was observed at two planting site elevations (610 and 750m) to investigate whether seed source elevation or planting site elevation affects the bud opening date. At both planting sites the bud opening dates were not significantly different among the seedling groups from different seed source elevations. On the other hand, bud opening dates of seedlings planted at the lower elevation site were significantly earlier than those planted in the higher elevation site. It could be deduced from this study that the environment of the planting site rather than seed source elevation affects the bud opening date of Yezo spruce.     

Pronounced fluctuations of spruce bark beetle (Scolytinae: Ips typographus) populations do not invoke genetic differentiation

The dynamics of a recent outbreak of the spruce bark beetle (Ips typographus) in Switzerland was ruled by a devastating winter storm in 1999 and the drought and heat of the summer 2003. Starting from a similar level of population sizes, estimated as the rate of infested growing stock, beetle populations increased differently in magnitude and time among different regions in Switzerland. Accordingly, we expected local or regional genetic differentiation as a result of such repeated population expansion/breakdown dynamics. We analyzed 5 nuclear microsatellites of spruce bark beetles sampled from pheromone traps at 30 locations distributed over Switzerland. Our genetic results did not indicate any sign of population differentiation, structure, isolation by distance, or recent bottlenecks. This complete lack of genetic structure suggests that spruce bark beetles are highly mobile, precluding the formation of a spatial structure at neutral molecular markers. Thus, this molecular–genetic approach does not allow us to discriminate among regional gene pools and to identify the origin of expanding beetle populations.     

Effects of bark stripping by sika deer, Cervus nippon, on wind damage to coniferous trees in subalpine forest of central Japan

We evaluated the effect of bark stripping by sika deer (Cervus nippon), and subsequent wood decay, on tree fall in a coniferous forest on Mt Ohdaigahara in central Japan from July to September 2006. This valuable primeval coniferous forest is declining because of bark stripping. Broken trunks of Abies homolepis and Picea jezoensis var. hondoensis had more serious decay and larger bark-stripping wounds on the trunk than standing trees, suggesting that bark stripping causes trunk decay and results in broken trunks and uprooting by typhoons.     

<Emphasis Type="Italic">Ophiostoma</Emphasis> species associated with bark beetles infesting three <Emphasis Type="Italic">Abies</Emphasis> species in Nikko,Japan

Ophiostoma species were isolated from bark beetles and Abies mariesii, A. veitchii and A. homolepis attacked by the beetles in Nikko, Tochigi, central Honshu, Japan. One to two Ophiostoma species were frequently isolated from each species of bark beetle. Ophiostoma subalpinum was the most common associate of Cryphalus montanus. Ophiostoma sp. B as well as O. subalpinum was a common fungus associated with Polygraphus proximus. Ophiostoma europhioides was isolated from Dryocoetes hectographus and D. autographus as one of the common associates. Ophiostoma sp. J and Ophiostoma sp. S were frequently isolated from D. autographus and D. striatus, respectively. These fungi seem to have specific relationships with particular bark beetles. Ophiostoma sp. B, Ophiostoma sp. J and Ophiostoma sp. S have unique morphological characteristics and appear to be new species. Five trees of A. veitchii, approximately 43 years old, were inoculated with five Ophiostoma species to assess the relative virulence of the fungi. Ophiostoma subalpinum, Ophiostoma sp. B, and O. europhioides had relatively higher virulence than the other species studied.     

Prevalence and incidence of the root-inhabiting fungi, Fusarium, Cylindrocarpon and Pythium, on container-grown Douglas-fir and spruce seedlings in British Columbia

Surveys were made at the end of the 1990 and 1991 growing seasons for root-inhabiting fungi in the genera Fusarium, Cylindrocarpon and Pythium from the roots of one year-old container-grown Douglas-fir and spruce seedlings grown under greenhouse conditions. In the 1990 survey of four nurseries, it was found that 61–97% of both Douglas-fir and spruce roots were colonized with Fusarium, Cylindrocarpon or Pythium. There were significantly (p0.05) more Douglas-fir roots than spruce roots colonized by Fusarium at all nurseries, however, there were significantly (p0.05) more spruce roots than Douglas-fir roots colonized by Cylindrocarpon and Pythium. Root colonization of Douglas-fir and spruce by the three fungal genera during 1991 varied from 0–82% at three nurseries, however, only at a south coastal nursery was there significantly (p0.05) more spruce than Douglas-fir roots colonized by Cylindrocarpon. Significantly more seedlings were infected in 1990 than in 1991. In 1991, there were few significant differences between Douglas-fir and spruce, in the percentage of seedlings with colonized roots and in the percentage of growth medium colonized by the fungi. However, there were significant differences between nurseries.     

The importance of seedling competition in the segregation of spruce and fir in the southern Appalachians

Fraser fir (Abies fraseri [Pursh] Poir.) and red spruce (Picea rubens Sarg.) are codominants of southern Appalachian spruce-fir forests. Fraser fir generally dominates above 1740 m, while red spruce usually dominates below this elevation. This study was designed to determine whether the present segregation of the two species along elevational gradients is associated with seedling competition or contrasting physiological responses to environmental factors. Seedlings were grown for two years in a replacement series experiment along two elevational transects extending from 1300 m to 1900 m, and harvested for growth analysis.Competition increased with decreasing elevation and Fraser fir was apparently the stronger competitor. Mortality was inversely correlated with elevation and was most evident in red spruce in May, and in fir in late summer. Fir growth increased with elevation and red spruce grew most at the middle elevation (1600 m). Neither competitive interactions nor growth responses completely explained the elevational segregation of red spruce and Fraser fir. We hypothesize that the early-successional Fraser fir quickly dominates at higher elevations following disturbance and that continued disturbance will favor its dominance at higher elevations. However, the late-successional noncompetitive red spruce slowly establishes itself and, while consistently present, may only dominate in the absence of disturbance and where other species are at the margins of their distribution.     

Selection of efficient VA mycorrhizal fungi for Casuarina equisetifolia—second screening

An investigation was carried out to screen and select efficient vesicular arbuscular mycorrhizal (VAM) fungi for inoculating the forest tree species, Casuarina equisetifolia. The seedlings were inoculated with 10 different VAM fungi, obtained from various sources. Inoculated seedlings generally had greater plant height, stem girth, biomass and P content than uninoculated plants. They also had more mycorrhizal root colonization and spore numbers in root zone soil. C. equisetifolia seedlings responded best (in biomass) to inoculation with Glomus mosseae (Nicolson and Gerdemann) Gerdemann and Trappe, closely followed by Acaulospora laevis Gerdemann and Trappe and G. fasciculatum (Thaxter Sensu Gerdemann) Gerdemann and Trappe; all the three being statistically on par with each other.     

Comparison of growth response ofAbies andPicea species to climate in Mt. Norikura, Central Japan

Tree-ring chronologies were developed fromAbies mariesii Masters andPicea jezoensis ssp.hondoensis (Mayr) P. Schmidt collected at different altitudes of Mt. Norikura, central Japan. The tree-ring parameters of ring width and maximum density were measured by soft X-ray densitometry. The measurement series were detrended by fitting a 33-year cubic smoothing spline and autoregressive model. The correlation between species and between sites showed different responses of the species to climate in terms of ring width and maximum density. The correlation coefficient between sites within a species was higher than that between species for a site in the ring width, and the coefficient between species for a site was higher in maximum density. The correlation coefficient between tree-ring chronology and monthly climate data set showed different responses of radial growth to climate. The different response was probably explained by the difference in the length of the growing season. High summer temperature increased the maximum density of the two species and the radial growth inAbies mariesii. Summer precipitation correlated negatively to maximum density, but it did not affect the ring width of either species. The climatic signals could be extracted from ring-width and maximum-density chronologies of both species.     

Effects of seed size on seedling attributes in Sitka spruce

No statistically-significant effects of size (small and large) of wind-pollinated seeds from 18 seed-orchard clones could be found in the attributes of 8-month-old seedlings of Sitka spruce (Picea sitchensis (Bong.) Carr.). Clonal variations in seedling attributes was highly significant (P < 0.01), but these variations were within regional specifications for operationally-produced nursery stock.     

Resistance of larches to bark stripping by sika deer in Hokkaido,northern Japan

Resistance of the Japanese larch (Larix kaempferi) (Lk), the Kurile larch (L. gmelinii var. japonica) (Lg), and their F₁ hybrid (Lg × Lk) to bark stripping by sika deer (Cervus nippon yesoensis) were studied in a forest in Hokkaido by cafeteria tests. Several sets of logs prepared from Lk, Lg, and Lg × Lk were fed to the deer. The stripped areas of logs significantly differed between the Lk/Lg set and the Lk/Lg × Lk set (P 0.05). The resistances of Lg and Lg × Lk to bark stripping was stronger than Lk. This result was similar to those of previous studies on gray-sided voles and mountain hares in Hokkaido.     

Blue stain fungi associated withIps cembrae (Coleoptera: Scolytidae) in Japanese larch in connection with their brood development

The association between blue stain fungi andIps cembrae Heer (Coleoptera: Scolytidae) was investigated in the Japanese larch,Larix leptolepis Gordon, in the Nagoya University Forest, Aichi Prefecture, central Japan.I. cembrae had one or two generation(s) in a year in this study area. Two blue stain fungi,Ophiostoma piceae andLeptographium sp., were isolated from the body surface of both male adults in mating chambers and female adults in parent galleries, suggesting that this beetle species was a vector of these fungi. Although no blue stain fungi were isolated from non-stained wood, both fungi were isolated from the mating chambers, the center and the uppermost end of the galleries throughout the season. The fact thatO. piceae was consistently isolated with high frequency from adults and from their galleries strongly suggested that this species would be the principal blue stain fungus infecting the beetle-attacked larch trees.     

Deer-proof fence prevents regeneration of Picea jezoensis var. hondoensis through seed predation by increased woodmouse populations

The indirect consequence of sika deer (Cervus nippon) grazing on the regeneration of Picea jezoensis var. hondoensis through its effect on the small rodent population was assessed by evaluating seed predation by mice inside and outside the deer-proof fence on Mt Ohdaigahara, central Japan. Following construction of the deer-proof fence, Sasa nipponica, which covers the forest floor and is the main forage of deer, grew thicker inside the fence due to the absence of deer grazing than outside of the fence. Higher numbers of two species of woodmice (Apodemus speciosus and A. argenteus) were found inside the fence, possibly because the thick S. nipponica growth provides better cover. Inside the fence, more seeds of P. jezoensis var. hondoensis were eaten by the mice than outside the fence. These results suggest that the mouse populations inside the fence increased due to changes in S. nipponica cover, which subsequently increased seed predation by the mice, possibly preventing regeneration of P. jezoensis var. hondoensis.     

Generalized allometric volume and biomass equations for some tree species in Europe

Since biomass is one of the key variables in ecosystem studies, widespread effort has aimed to facilitating its estimation. Numerous stand-specific volume and biomass equations are available, but these cannot be used for scaling up biomass to the regional level where several age-classes and structural types of stands coexist. Therefore simplified generalized volume and biomass equations are needed. In the present study, generalized biomass and volume regression equations were developed for the main tree species in Europe. These equations were based on data compiled from several published studies and are syntheses of the published equations. The results show that these generalized equations explain 64–99% of the variation in values predicted by the original published equations, with higher values for stem than for crown components.

Reduction of frost heaving of Norway spruce and Scots pine seedlings by planting in mounds or in humus

This study was carried out in northern Sweden to determine the effects of frost heaving on the establishment of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings in relation to planting methods. For this purpose, one year old containerised seedlings were planted on two sites and on two dates: during the spring (early planting) and during the fall (late planting). In each case, two planting depths (normal and deep planting) and four planting sites (in mineral soil in the depressions, in the scalp/trench area, on the top of the mound and in the untreated humus layer) were used. On each site, 50 seedlings were planted for each treatment. Frost heaving was observed and measured during two years. The amount of heaving was highest in the hole and almost insignificant on the top of the mound and in the humus layer. Planting depth influenced the degree of heaving only for Scots pine planted in the hole and was not related to the planting time.     

Effects of surface and light conditions of fallen logs on the emergence and survival of coniferous seedlings and saplings

We surveyed the germination number (N _cs) of 2-year and a 1-year survival of Abies sachalinensis and Picea jezoensis seedlings and saplings on 29 fallen logs from 2004 to 2005 in a natural coniferous forest in Hokkaido, northern Japan, in relation to the surface and light conditions of fallen logs. Moss height (H _moss), log hardness (Hardness), and the area of fallen log (Area) were measured as the surface conditions by each 1-m block from bottom to top of all fallen logs. The relative photosynthetic photon flux density (rPPFD) 10 cm above the tallest seedling in each block was measured as the light condition. In addition, the height of the tallest seedling or sapling in each block (H _max), the difference between a height of each seedling and sapling and the H _max (Shading), and a height of seedlings and saplings in 2004 (H _ini) were considered. N _cs of A. sachalinensis was affected by Hardness and Area, whereas N _cs of P. jezoensis was affected by H _moss, Hardness, Area, H _max, and rPPFD. The survival of seedlings (height < 5 cm) and saplings (5 cm ≤ height < 50 cm) were affected by H _ini, rPPFD, and shading for both species. However, the survival of P. jezoensis saplings was more sensitive to decrease in rPPFD and increase of shading than that of A. sachalinensis. Therefore, seedling emergence was influenced by surface conditions, whereas survival was affected by light conditions. Furthermore, P. jezoensis emergence and survival were more sensitive to surface and light conditions than that of A. sachalinensis.     

Larssoniella duplicati n.sp. (Microsporidia, Unikaryonidae), a newly described pathogen infecting the double-spined spruce bark beetle, Ips duplicatus (Coleoptera, Scolytidae) in the Czech Republic

Larssoniella duplicati n.sp. infects the midgut muscularis, the Malpighian tubules, and the ovaries of adult Ips duplicatus (Sahlb.) in the Czech Republic. The microsporidian attacks up to 50% of the population. Oval spores of two sizes, 3–3.5×1.5–2 and 2–2.5×1.5 μm have the polar filament coiled in 6/7 coils, representing primary and environmental spores, respectively. In early sporogony the young spores produce long electron dense threads and tubules of secretions, which remain fixed around the spore and avoid their free release during dissection of infected hosts. The microsporidian was not found in associated bark beetles such as Ips typographus (L.), or I. amitinus (Eichh.) and others.     

Temporal variation and efficiency of leaf area index in young mountain Norway spruce stand

Temporal variation of leaf area index (LAI) in two young Norway spruce stands with different densities was monitored during eight consecutive growing seasons (1998–2005). We focused on: (1) LAI dynamics and above-ground mass production of both spruce stands and their comparison, (2) leaf area duration (LADU), crop production index (CPI) and leaf area efficiency (LAE) evaluation, and (3) thinning impact on the above-mentioned parameters. Also, we tried to deduce the most effective LAI value for the Norway spruce forest investigated. The LAI values of both spruce stands showed a typical seasonal course. To describe the LAI dynamics of the stand, we recommend taking LAI measurements within short time intervals at the time of budding and needle expansion growth (i.e., in early spring) and close to the LAI peak, when the twig growth has been completed. The reason was that after reaching the seasonal maximum, no significant differences between subsequently obtained values were found in the following 2 months. Therefore, we recommend this period for the estimation of seasonally representative LAI values, enabling the comparison of various spruce stands. The maximum hemi-surface LAI value reached 12.4. Based on our results, the most effective LAI values for maximum above-ground biomass production were within the range of 10–11. We found an LAI over these values to be less effective for additional production of above-ground biomass. In forest practice, thinning intensity is mostly described by percentage of stocking reduction. We want to show that not only thinning intensity, but also the type of thinning is important information. The type of thinning significantly affected the stand above-ground biomass increment, canopy openness, stand LAI and LAI efficiency. The stimulating effect of high-type thinning was observed; the LAE as well as the CPI increased. Low-type thinning had no such effects on LAE increments compared to the high-type thinning with similar intensity.

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The effects of Douglas-fir on tree-specific arthropod communities in mixed species stands with European beech and Norway spruce

The ecological effects of planting exotic Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] in Central Europe are still poorly understood. The aim of this study was to answer the question of whether Douglas-fir affects tree specific arthropod communities in different mature forest types (Douglas-fir, spruce and beech dominated) in Southern Germany. Therefore, arthropod communities of stem and tree crown strata of Douglas-fir and spruce (Picea abies L.) were sampled in the years 1999–2001 using arboreal photo-eclectors and flight interception traps. Statistical analysis was conducted for all species and focused on conifer specialists at three levels: (1) species diversity, (2) guild structure and (3) community structure. Within the stem stratum, species diversity was significantly higher on spruce than on Douglas-fir independent of year and stand composition. This could not be explained by a single feeding guild, rather by species changing strata during the vegetation period. In contrast, species diversity in tree crowns was approximately the same for both conifer species. However, communities in Douglas-fir crowns were conspicuously different from those in spruce crowns, especially in the Douglas-fir dominated stand type. While zoophagous insects exhibited higher activity on Douglas-fir in 2000, xylophagous beetles were more abundant on spruce in 2001. In European beech stands with widely spaced Douglas-fir trees, the site specific and broad-leaved tree related fauna might be maintained. In addition, Douglas-fir with its resource of Adelges cooleyi and crowns that overtop the broad-leaved tree canopy, offer additional resources for several aphidophagous and thermophile species.