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1.
Lessons Learned on a Wilderness Medicine “Teaching Weekend” 总被引：1，自引：1，他引：0
2.
We investigated the biomass, vertical distribution, and specific root length (SRL) of fine and small roots in a chronosequence
of Japanese cedar (Cryptomeria japonica D. Don) plantations in Nara Prefecture, central Japan. Roots were collected from soil blocks up to 50 cm in depth in five
plantations of differing age: 4, 15, 30, 41, and 88 years old. Fine-root biomass reached a maximum (639 g m−2) in the 15-year-old stand before canopy closure, decreased in the 30-year-old stand (422 g m−2), and thereafter was stable. Except in the 30-year-old stand, fine-root biomass increased in deeper soil layers as stand
age increased, and the depth at which the cumulative biomass of fine roots reached 90% exhibited a good allometric relationship
with mean stem diameter. Both root-length density (root length per unit soil volume) and SRL decreased with soil depth in
all stands, indicating that plants mainly acquire water and nutrients from shallow soils. The highest SRL was observed in
the 4-year-old stand, but the relationship between SRL and stand age was unclear in older stands. The SRL in surface soils
seemed to decrease with increases in root-length density, suggesting that branching of the fine-root system during development
is related to density-dependent processes rather than age. 相似文献
3.
Root biomass and root distribution were studied in Entisols derived from the thick deposition of volcanic pumice on Hokkaido
Island, Japan, to examine the effect of soil conditions on tree root development. The soil had a thin (<10 cm) A horizon and
thick coarse pumiceous gravel layers with low levels of available nutrients and water. Two stands were studied: a Picea glehnii–Abies sachalinensis stand (PA stand) and a Larix kaempferi–Betula platyphylla var. japonica stand (LB stand). The allometric relationships between diameter at breast height (DBH) and aboveground and belowground biomass
of these species were obtained to estimate stand biomass. The belowground biomass was small: 30.6 Mg ha−1 for the PA stand and 24.3 Mg ha−1 for the LB stand. The trunk/root ratios of study stands were 4.8 for the PA stand and 4.3 for the LB stand, which were higher
than those from previous studies in boreal and temperate forests. All species developed shallow root systems, and fine roots
were spread densely in the shallow A horizon, suggesting that physical obstruction by the pumiceous layers and their low levels
of available water and nutrients restricted downward root elongation. The high trunk/root ratios of the trees may also have
resulted from the limited available rooting space in the study sites. 相似文献
4.
Jürgen Gross Nina E. Fatouros Seppo Neuvonen Monika Hilker 《Journal of pest science》2007,80(3):139-143
The Palaearctic leaf beetle Chrysomela lapponica usually feeds upon willows in the northern region of its occurrence. However, in Central Europe, some populations are known
that have specialised on birch. In this study, we investigated the significance of other herbivores occurring together on
the same host plants as possible exploitative competitors of C. lapponica. Two populations were studied: a population from Finland specialised on the willow Salix
borealis, and a population from the Czech Republic, specialised on the birch Betula
pubescens. Abundances of folivorous and suctivorous insects on both host plants were recorded at both population sites. The willow
leaf beetle Phratora vitellinae was the most abundant herbivorous insect at both study sites on willow. A field study was conducted to examine the effects
of P. vitellinae on the performance of C. lapponica. The presence of P. vitellinae larvae on the same twig upon which C. lapponica larvae were feeding did not affect increase of body weight in C. lapponica larvae. Thus, the high resource availability of both willows and birches suggest that interspecific competition is unlikely
to be a selection factor driving the evolution of host shift in C. lapponica. 相似文献
5.
Demand for goat (Capra hircus) meat in the southeastern USA is steadily increasing as a result of preferences exhibited by ethnic communities. Feeding
systems that include fodder trees can be developed to take advantage of the natural preference of goats for browse. Data were
collected for 2 years on a 5-year old stand of Robinia pseudoacacia L. to evaluate growth characteristics for goat browse and to develop allometric relationships in a randomized complete block
design (intra-row spacing 0.5 or 1 m and coppice height 0.25 or 0.50 m) replicated six times. Allometric equations were derived
from destructive harvests of 68 trees. Main branch size was not affected by intra-row spacing when trees were coppiced at
0.25 m; however, when coppiced at 0.5 m, trees spaced at 1 m had more and larger branches (P < 0.05) than trees spaced at 0.5 m. Intra-row spacing did not influence tree herbage biomass when trees were spaced at 0.5 m
whereas trees coppiced at 0.25 m and spaced at 1 m produced less woody and herbaceous biomass than trees spaced at 0.5 m (P < 0.05). A strong relationship (P < 0.0001) was found between tree herbage biomass and the number of main branches greater than 0.01 m (r
2 = 0.80). The results, based on growth characteristics and tree herbage biomass production, suggest that Robinia pseudoacacia L. would be an excellent candidate as a silvopastoral component in the southeastern USA. 相似文献
6.
Picea mongolica is an endemic but endangered species in China. The spruce forest is only found in sandy forest-steppe ecotones. In this study, we examined the initial response of the quantity and refilling process of fine roots in an artificial canopy gap with a diameter of 36 m in a P. mongolica forest. Under the canopy, the fine root length densities of trees, shrubs and herbs were 2,622, 864 and 3,086 m·m–2, respectively. The fine root biomass of trees, shrubs and herbs were 148, 62 and 65 g·m–2, respect... 相似文献
7.
To find fungi that are potent for degradation of condensed tannin, a two-step screening was used. This involved measurement
of fungal growth rate on Japanese cedar (Cryptomeria japonica) bark, followed by determination of [14C]-labeled CO2 generated from fungal degradation of synthetic [14C]-labeled condensed tannin model. In the first screening, 75 strains of wood rot fungi were tested, and 19 strains effectively
decreased bark weight and/or the weight of the methanol-soluble fraction. For the second screening, [14C]-labeled condensed tannin model compound was synthesized in 11.8% yield based on radioactivity measurements. Over the incubation
period, Coriolus hirsutus K-2671, Lentinus edodes Is, and Lampteromyces japonicus Nn showed higher cumulative [14C]-labeled CO2 emissions than the other strains and mineralized the [14C]-labeled condensed tannin model compound by 3.7%, 3.0%, and 3.0%, respectively. Fractionation of the methanol extracts from
the medium by gel permeation chromatography after fungal treatment suggested that fungi that can induce the emission of significant
levels of [14C]-labeled CO2 can extensively depolymerize condensed tannins. 相似文献
8.
Wang Wei-gang Ma Lei Jiang Jian-xin Jiang Li Zhang Zhi-xiang 《中国林学(英文版)》2007,9(2):132-136
Studies were carried out on the transesterification of the Chinese Spicehush (Lindera communis) seed (LCS) oil with methanol for the production of biodiesel. The methyl esters of LCS oil were compared with soybean esters to determine biodiesel fuel performance and properties. The fatty acids content in the seed kernel oil (LKO) and coat oil (LCO) were quantified by gas chromatography and mass spectrometry method (GC-MS). LKO contains 95.1% saturated acids (capric, lauric, myristic and palmitic) and 2.3% unsaturated acids (oleic). LCO contains 24.6% saturated acids (palmitic and stearic) and 73.6% unsaturated acids (oleic, linoleic and palmitoleic). The kinematic viscosity, cold filter plugging point, cloud point, flash point and cetane index were determined. The methyl esters of LKO had a higher kinematic viscosity and a lower cold filter plugging point value, so it has better per- formance in cold weather. The biodiesel of LCS oil has fuel properties within the limits prescribed by American (ASTM D 6751-02) standards, except for a slightly lower flash point of LKO biodiesel than that prescribed by these standards (130°C). Thus, LKO and LCO biodiesel have great potential to be used on a large scale as fuel for diesel engines. 相似文献
9.
Introduction of Pinus radiata for afforestation： a review with reference to Aba, China 总被引：3，自引：0，他引：3
BIHui-quan JackSimpson LIRong-wei YANHong WUZong-xing CAIShi-min RobertEldridge 《林业研究》2003,14(4):311-322
Pinus radiata D. Don, native to a Californian coastal environment, has been introduced to many parts of the world as an exotic species for afforestation. It is now a major plantation species in the Southern Hemisphere. In 1990, it was introduced to the heavily degraded, dry Min river valley area in Aba prefecture of Sichuan Province, P. R. China. Survival and growth of young trees planted at several sites appear to be reasonable. This review is to serve as an introduction to the large body of literature on P.radiata for forest scientists in China. It covers the following aspects: P. radiata in its native environment and in ex situ plantations,provenance and genetic variations, environmental limitations and climate niche, diseases and pests, lessons from unsuccessful introductions, and the use of P. radiata for ecological restoration. The early growth of P. radiata planted in the dry river valley area is briefly described. Potential problems associated with the introduction of P. radiata in Aba and future research needs are also identified. 相似文献
10.
The ambrosia beetle Platypus quercivorus causes mass mortality of Fagaceae trees in Japan, and tree species differ in their susceptibility to P. quercivorus. We hypothesized that interspecific differences in susceptibility are caused by differences in beetle infestation patterns,
that is, how many beetles fly to a tree and how many of those arriving bore holes. To examine how tree susceptibility is related
to these parameters, two tree species with different degrees of susceptibility were studied (highly susceptible Quercus crispula and less susceptible Q. salicina). Specifically, we measured the number of male beetles per unit area that flew to the host trees (NFM) and the density of
holes bored by male beetles (DH). From these two values, we calculated the proportion of male beetles flying to a host tree
that bored holes (PBM). These parameters were compared for the two Quercus species. Although the two species did not differ in NFM in 2003, PBM was markedly lower for Q. salicina than for Q. crispula and DH was significantly lower for Q. salicina than for Q. crispula. Thus, the lower susceptibility of Q. salicina is partly explained by its low PBM. 相似文献
11.
To clarify the effects of inundation on the establishment of Salix gracilistyla trees, the relationship between total inundation duration and the distribution and size of trees was examined on a gravel
bar along the Miya River in central Japan. The density of S. gracilistyla was low at both low and high elevations on the gravel bar, but high at middle elevations. The density increased with up to
165 days of inundation and declined gradually with more than 165 days of inundation. Density had a negative effect on crown
area, whereas inundation duration had a positive effect. At lower elevations, growth limitation of S. gracilistyla is mainly caused by inundation stress, whereas at higher elevations it seems to be primarily due to drought stress, although
it depends on the total duration of inundation in a year (TDIY). Consequently, the density is highest at middle elevations
where trees do not become too large. These results suggest that inundation duration is one factor determining the density
of S. gracilistyla trees, which in turn affects the size of each tree. 相似文献
12.
Soil respiration and soil carbon dioxide (CO2) concentration were investigated in a tropical monsoon forest in northern Thailand, from 1998 to 2000. Soil respiration was relatively high during the rainy season and low during the dry season, although interannual fluctuations were large. Soil moisture was widely different between the dry and wet seasons, while soil temperature changed little throughout the year. As a result, the rate of soil respiration is determined predominantly by soil moisture, not by soil temperature. The roughly estimated annual soil respiration rate was 2560gCm–2year–1. The soil CO2 concentration also increased in the rainy season and decreased in the dry season, and showed clearer seasonality than soil respiration did. 相似文献
13.
Given the sequence of Chs gene promoter from Arabidopsis thaliana reported in GenBank (AF248988), a pair of specific 相似文献
14.
Spatial distribution of sporocarps of Suillus pictus A.H. Smith and Thiers was studied in a plot of 6 × 12 m in size established in a stand of Pinus koraiensis Sieb. et Zucc. in Kyoto, Japan for 4 years, and the biomass of mycorrhizas was examined in the last year. S. pictus was dominant in both sporocarp and ectomycorrhizal community in the study plot. The number of S. pictus sporocarps ranged from 0.94 to 1.26 m−2 (surface area) in the study plot and did not vary very much during the study period. Sporocarps of S. pictus occurred in clumps and the distributions of clumps were generally random. As the spots of sporocarp occurrence changed gradually
from year to year, the distributions of sporocarps that occurred successively in 2-year periods overlapped, especially when
analyzed in 9-m2 unit size using the m
*
–m method. Mycorrhizas of S. pictus were distributed in more subplots than its sporocarps. Distribution of mycorrhizas and sporocarps of S. pictus generally overlapped well. The biomass of mycorrhizas and mycelia in the mycorrhizas of S. pictus was estimated at 15.5 g DW m−2 and 6.2 g DW m−2 (surface area) in this plot, respectively. The biomass of mycorrhizas and mycelia in the mycorrhizas supporting the production
of one sporocarp (average dry weight was 0.86 g) of S. pictus was evaluated as about 16.4 and 7.3 g DW, respectively, in this plot.
Received: December 20, 2001 / Accepted: August 12, 2002
Acknowledgments We thank Dr. T. Furuno, Mr. N. Kato, and Dr. I. Nakai for their help in preparing the study plot and collecting sporocarps,
and Prof. K. Yokoyama for the identification of sporocarps. Thanks are also due to Dr. E. Kuno for his suggestion about analysis.
Correspondence to:J. Kikuchi 相似文献
15.
An efficient and improved shoot regeneration technique for the micropropagation of Vitex negundo, an aromatic and medicinal shrub through in vitro culture of nodal segments with axillary buds, is described. Thidiazuron
(TDZ) used at 1.0 μM was the most effective in inducing bud break and growth, and also in initiating multiple shoot proliferation
at the rate of 25 microshoots per nodal explant with axillary buds, after 4 weeks of culture. By repeated subculturing of
nodal explants, a high-frequency multiplication rate was established. Optimum shoot multiplication and elongation was achieved
when TDZ exposed explants were subcultured on Murashige and Skoog (MS) media containing a combination of 1.0 μM 6-benzyladenine
(BA) and 0.5 μM α-naphthalene acetic acid (NAA). Efficient rooting was achieved directly in soilrite when basal portion of
the shoots were treated with 500 μM indole-3-butyric acid for 10 min which was the most effective in inducing roots, as 97%
of the microshoots produced roots. Plantlets went through a hardening phase in a controlled plant growth chamber, prior to
ex-vitro transfer. Micropropagated plants grew well, attained maturity and flowered. No phenotypical differences for morphogenesis
were observed among the regenerants. 相似文献
16.
17.
Dutch elm disease (DED) has spread through Europe and North America since the beginning of the twentieth century. In response, several independent genetic improvement programmes for breeding DED‐resistant elms have been established on both sides of the Atlantic. Assimilating a wide range of resistant clones of different parentage should help ensure survival of the elm in the event of mutation of the pathogen. The Italian elm breeding programme began in the late 1970s and has recently raised a new variety by crossing a specimen of U. chenmoui with the Dutch hybrid clone ‘405’. This new release, named ‘Morfeo’, is extremely resistant to DED and has an attractive form and foliage. It is also fast‐growing, tolerant of drought and soils waterlogged in winter, therefore proving well adapted to the climates of both north‐western Europe and the Mediterranean. Following trials in England, ‘Morfeo’ is considered of potential importance in the conservation of several invertebrates endangered by the consequences of DED. 相似文献
18.
Susumu Kurinobu Daryono Prehatin Naiem Mohanmad Kenji Matsune Osamu Chigira 《Journal of Forest Research》2007,12(3):230-236
A growth model for a plantation of Paraserianthes falcataria was provisionally derived from measurements of 32 permanent plots taken over a period of 2 years in Pare, Indonesia. This
model first predicts height growth with the polymorphic site index equation. Then density-related growth and mortality, that
is, diameter and stand density, are calculated to satisfy the mathematical relationship for the reciprocal and self-thinning
equations, both of which were based on the maximum size–density line with the slope of −1.759 identified in this study. Cumulative
predictions on diameter and stand density, starting with each of three age classes, 3, 4, and 5 years after planting, and
continuing for the next 2 years, agreed well with the observations of age-class mean. An exception was for stands that were
7 years old, which were marginal, but closest to the rotation age of 8 years. Contrasting height/diameter relationships among
the three age classes were described reasonably well with this model, and the predicted basal growth area was found to agree
fairly well with observations. These results suggest that the growth model presented here has good potential for applying
size–density control for plantations of P. falcataria. However, measurements for an additional few years might be necessary to derive a model that will more accurately predict
diameter size at the rotation age. 相似文献
19.
We have developed a 247-year ring-width chronology of Betura ermanii Cham. growing in an open canopy forest close to the tree line at a coastal site in southern Kamchatka. Climatic response
analyses revealed that the ring width was primarily controlled by July–August temperature. The regression models that we used
for statistical reconstruction passed the stringent calibration–verification tests used in dendroclimatology, resulting in
the first quality-controlled tree-ring reconstruction for southern Kamchatka. The reconstructed temperature shows a cool period
from the 1830s to the 1880s, followed by gradual warming until ca. 1940, then a cooling trend extending to the 1970s, and
finally a warming trend continuing to the present. Spatial correlation analyses with sea surface temperature in the North
Pacific indicated that the seas surrounding the Kamchatka peninsula play a role in modulating temperature variations in the
study area whereas the effects of the Pacific Decadal Oscillation are relatively weak. 相似文献
20.
H.‐Q. Mou X. Xu R.‐R. Wang Q. Tian Y. Wei S.‐F. Zhu X.‐L. Liao W.‐J. Zhao 《Forest Pathology》2014,44(1):56-61
This article reports Salix tetradenia Hand.‐Mazz as a new host of Candidatus phytoplasma and demonstrates its association with witches' broom disease on S. tetradenia plants. Plants exhibited typical visual symptoms of phytoplasma with virescence, abnormality of flowers and witches' broom, and phytoplasma bodies were observed by transmission electron microscopy. Products of 1.2 kb were amplified by nested PCR using phytoplasma universal primer pairs R16F2n/R16R2, but no amplification products were obtained from symptomless plants. The sequence analysis of three 16S rDNA isolates showed 99.84%, 99.68% and 99.76% identify, respectively, with the homologous gene (nc_005303) of member of ‘Candidatus phytoplasma asteris’ (16SrI) group. Phylogenetic and virtual computer‐simulated restriction fragment length polymorphism analysis of the 16S rRNA, tuf and rp gene sequences confirmed that this phytoplasma clustered in the 16SrI‐B subgroup. These results indicated that the diseased S. tetradenia plants were infected by a phytoplasma of the 16SrI group. This is the first report on the occurrence of phytoplasma disease on S. tetradenia worldwide. 相似文献