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1.
An observational study of early seedling establishment (first 1–2 summers after emergence) was conducted in four ponderosa
pine (Pinus ponderosa var. ponderosa Dougl. ex Laws.) stands east of the Cascade Range crest in central Oregon, USA. Newly emerged ponderosa pine seedlings were
identified at the start of summer and were monitored through their second summer; a subsequent cohort of seedlings was identified
and monitored for one summer. About 3% of the viable seed that was produced resulted in new seedlings. Mortality was substantial
immediately following emergence. Most seedlings emerged without shading from understory vegetation, but few survived. Most
seedlings alive after one year had emerged beneath live cover; by the end of two summers only shaded seedlings were alive.
63–85% of new seedlings initiated in clusters attributed to rodent caching, and seedlings originating in clusters remained
a substantial proportion of the cohort (60%) after two seasons. Results suggest that understory vegetation in these types
of stands facilitates the recruitment of ponderosa pine seedlings, most likely by buffering them against environmental stressors
during the seedling establishment phase. They also reveal that seed caching rodents are highly active in seed redistribution
and can exert a lasting influence on seedling recruitment. 相似文献
2.
Guillermo Trincado Curtis L. VanderSchaaf Harold E. Burkhart 《European Journal of Forest Research》2007,126(2):253-262
A height–diameter mixed-effects model was developed for loblolly pine (Pinus taeda L.) plantations in the southeastern US. Data were obtained from a region-wide thinning study established by the Loblolly
Pine Growth and Yield Research Cooperative at Virginia Tech. The height–diameter model was based on an allometric function,
which was linearized to include both fixed- and random-effects parameters. A test of regional-specific fixed-effects parameters
indicated that separate equations were needed to estimate total tree heights in the Piedmont and Coastal Plain physiographic
regions. The effect of sample size on the ability to estimate random-effects parameters in a new plot was analyzed. For both
regions, an increase in the number of sample trees decreased the bias when the equation was applied to independent data. This
investigation showed that the use of a calibrated response using one sample tree per plot makes the inclusion of additional
predictor variables (e.g., stand density) unnecessary. A numerical example demonstrates the methodology used to predict random
effects parameters, and thus, to estimate plot specific height–diameter relationships. 相似文献
3.
L. G. García-Montero J. L. Manjón S. Martín-Fernández G. Di Massimo 《Agroforestry Systems》2007,70(3):243-249
In Mediterranean pine forests, truffles and mushrooms generate greater profits than any other woodland products. However,
there are no studies on Tuber melanosporum Vittad. associated with pines. For this reason, we have carried out a study of this truffle in mountain woods with Pinus sylvestris L. and P. nigra Arnold subsp. salzmannii (Dunal) Franco, in central Spain. Two hundred and eight Tuber melanosporum burns were monitored for 7 years in five different habitats within the same geographical area. An ANOVA test confirmed significant
differences in carpophore production. In higher producing habitats, pines were less abundant. We also confirmed that in 433
burns, T. melanosporum was always unequivocally associated with the root base of Quercus or Corylus trees. Similarly, 14 truffle collectors confirmed that they had never found a single burn with carpophore production associated
exclusively with pines. Nevertheless, soil analyses indicated that the soil of these pine woods was very favourable to Tuber melanosporum. We therefore conclude that at present Pinus nigra
salzmannii and P. sylvestris are of little interest to Tuber melanosporum culture, as they hinder carpophore production. However, this study has also confirmed that Pinus nigra salzmannii and P. sylvestris mycorrhize easily with Tuber melanosporum, both in the laboratory and in natural environments. On this basis, we propose that pines may act as transmitters of T. melanosporum, although they do not induce fruiting. As a result, the commercial cultivation of Pinus nigra
salzmannii and P. sylvestris seedlings mycorrhized with Tuber melanosporum is not recommended in truffle culture at the present time. 相似文献
4.
The aim of this study was to determine changes in crystallinity and crystalline unit cell type of heat-treated Scots pine
(Pinus sylvestris L.) and Uludağ fir (Abies nordmanniana stev. subsp. bornmuelleriana Mattf.) wood samples by means of FT-IR spectroscopic method. Heat treatment was applied on the test samples in an oven at
three different temperatures (120, 150, and 180°C) and for two different periods of time (6 and 10 h) under atmospheric pressure.
It was designated that crystallinity of both Scots pine and Uludağ fir wood samples increased during heat treatment depending
on the duration. However, monoclinic structure in crystalline unit cells of Scots pine and Uludağ fir wood samples converted
to triclinic structure when heat treated. It was estimated that monoclinic structure was dominant in the crystalline unit
cell. It was established that the crystalline structure of Scots pine wood samples was more affected by heat treatment than
that of Uludağ fir wood samples. 相似文献
5.
Daniel Moreno-Fernández Fernando Montes Mariola Sánchez-González Francisco J. Gordo Isabel Cañellas 《European Journal of Forest Research》2018,137(1):17-27
The dynamics of mixed stands are more complex and less studied than those of monospecific stands. The objective of this work was to analyze the variables involved in seedling occurrence and seedling survival in mixed stands of Pinus pinaster and P. pinea in Mediterranean areas. From 2011 to 2016, regeneration of both species was monitored at two sites located in Central Spain. We installed 72 regeneration plots where seedling dynamics were monitored. All the trees in the study areas were measured and mapped. Additionally, we took hemispherical photographs in each regeneration plot. The average density of P. pinea seedlings over the study period was almost 20 times larger than that of P. pinaster. Our results indicate that the seedlings of both species grow under moderate light conditions. In addition, we found that the occurrence of seedlings of both species was related to the structure of the stand. P. pinea seedlings grew where the density and size of P. pinaster trees were low and where P. pinea trees provided moderately sheltered conditions, whereas the number of P. pinaster seedlings was related to under intermediate densities of P. pinaster trees. Furthermore, seedling survival was positively associated with age of the seedlings and negatively with the August average maximum temperature. The temporal continuity of mixed stands of P. pinea and P. pinaster in the study area is compromised by the observed lack of regeneration of P. pinaster. 相似文献
6.
Pinus patula and high-elevation (HE) sources of P. tecunumanii exhibit intermediate levels of resistance to pitch canker (Fusarium circinatum), compared to extremely resistant species such as P. oocarpa, and extremely susceptible species such as P. radiata. Seedlings from 20 P. patula provenances and 15 HE P. tecunumanii provenances were artificially inoculated with the pitch canker fungus at 21 and 12 weeks of age, respectively, and assessed
for resistance 12–20 weeks later. There was important provenance variation in pitch canker resistance for both species. The
20-week LiveStem percentage ranged from 70.3% to 43.6% among the P. patula provenances and 59.6% to 11.7% among HE P. tecunumanii provenances. There was a geographic pattern to the provenance variation, and in both species, low altitude sources demonstrated
more resistance than those from high elevation. Provenance variation in pitch canker resistance could be useful when making
selection and breeding decisions with these species. 相似文献
7.
The aim of the study was to investigate dynamics and pattern of natural regeneration and the influence of seedbed and light
on germination and initial seedling survival of Scots pine (Pinus sylvestris L.) during three growing seasons. Four 5-m2 plots in a natural Scots pine forest in central Spain were randomly established at the beginning of the regeneration process.
Germination and seedling survival were recorded in 100 regeneration sampling subplots (0.25 m2) per plot, while seedbed type and the relative light intensity reaching the forest floor was characterised in 1-m2 subplots. The spatial correlations between survival, light conditions and organic matter depth were analysed through cross-variograms.
Germination and survival were highly variable both within and between plots (ranging from 0 to 89%) and affected by high summer
temperatures (33–35°C) in 2003. The spatial pattern characterisation of survival by Ripley’s K function showed a dominant cluster distribution. Occurrence tended to be clumped when abundance was greater than 15 seedlings,
whereas for lower densities, seedlings were randomly distributed. Seedlings and herbs occupied the same sites where environmental
conditions were appropriate for them to live. Spatial association occurred frequently for light and organic matter depth.
Results suggested that the Scots pine seedlings in our study in central Spain preferred moderate light conditions (Global
Site Factor <0.40). Thus, if this forest is to be naturally regenerated with Scots pine, the shelterwood system (whereby some
mother trees are left to provide shelter for at least 5 years), along with mechanical disturbance of the seedbeds, would promote
seed germination, as long as a seed source is present. However, regeneration success is affected by year-to-year conditions. 相似文献
8.
Bruno Esteves António Velez Marques Idalina Domingos Helena Pereira 《Wood Science and Technology》2007,41(3):193-207
Heat treatment of Pinus pinaster and Eucalyptus globulus woods, two important species in Portugal, was performed in the absence of air by steaming, inside an autoclave, for 2–12 h
at 190–210°C. Mass losses increased with treatment time and temperature reaching 7.3% for pine and 14.5% for eucalypt wood.
The wood behaviour with moisture was improved. The equilibrium moisture content decreased by 46% for pine and 61% for eucalypt,
the dimensional stability increased (maximum anti-shrinking efficiency in the radial direction of 57 and 90% for pine and
eucalypt, respectively) and the surface wettability was lowered. In relation to mechanical properties, the modulus of elasticity
was little affected (maximum decrease of 5% for pine and 15% for eucalypt) but the bending strength was reduced (by 40% at
8% mass loss for pine and 50% at 9% mass loss for eucalypt wood). The variation of properties was related to treatment intensity
and mass loss but significant improvements could already be obtained for a 3–4% mass loss without impairing the mechanical
resistance. The response of eucalypt was higher than that of pinewood. Heat treatment of eucalypt wood shows an interesting
potential to improve the wood quality for solid timber products. 相似文献
9.
V. Sivakumar R. Anandalakshmi R. R. Warrier B. G. Singh Mulualem Tigabu P. C. Odén 《New Forests》2007,34(3):281-291
The germination of Casuarina equisetifolia Forst seed lots is low (40–50%) even when freshly collected. This study aimed at upgrading the germination performance by
removing non-germinable seeds using petroleum flotation technique. Seeds collected from 19 individual trees in seedling seed
orchards in India were assessed using X-ray to determine the proportion of different seed lot fractions. The feasibility of
petroleum ether as a separation medium was tested. Morphological characters of floating and sunken seeds were further studied
using image analysis technique to examine their effects on the separation efficiency. The X-ray analysis revealed a large
quantity of shrivelled, empty and insect-damaged seeds, altogether accounting 50%, which were the causes of low percentage
germination of un-graded seed lots (48%). Petroleum flotation resulted in 90% germination in the sunken fraction and 4% in
the floating fraction. The separation was distinct for most seed lots, except few seed lots that had relatively low germination
in the sunken fractions and more than 10% germination in the floating fractions. As a whole, petroleum flotation appears to
be a feasible technique to upgrade the germination of C. equisetifolia seed lots, and its efficacy is influenced by wing surface area, seed density and wing quotient of filled and empty seeds. 相似文献
10.
A. P. Dimitrakopoulos I. D. Mitsopoulos D. I. Raptis 《European Journal of Forest Research》2007,126(4):555-561
Nomographs that calculate the threshold values of surface fire parameters which lead to crown fire initiation were created
by linking two separate fire behavior models: Van Wagner’s crown fire ignition criteria and Byram’s surface fire model. The
nomographs were also based on the existing surface (fuel load, fuel heat content) and canopy (foliar moisture content, live
crown base height) fuel models of Aleppo (Pinus halepensis Mill.) pine forests of Mediterranean Greece. The most important fire parameters for crown fire initiation that are calculated
by the nomographs are the critical flame length and the forward spread rate of the surface fire. These parameters are readily
observable in the field during fires. The nomographs provide a judicious way to assess whether a crown fire is likely to occur
in a conifer forest stand. Although the fire behavior models used had limited testing and are based on certain assumptions,
yet they are widely applied in forestry practice worldwide, as a basis for justified fire prevention and suppression planning. 相似文献
11.
Thomas J. Straka 《New Forests》2010,40(2):165-173
Reestablishment of longleaf pine (Pinus palustris Mill.) in the American South is a priority of conservation groups. Its original Pre-European natural range of 38 million
ha has been reduced by 95% and it is one of the most endangered ecosystems in the US. The species undergoes a grass stage
where no stem development takes place that can last 7 years or longer. Competition control can limit this grass stage and
increase economic returns. The amount of competition control cost that equals the cost of the grass stage delay would be the
most one would want to expend in reducing the grass stage delay. This breakeven amount can be determined using land expectation
value methodology and a simple calculation technique is presented. A case study shows that each additional year of a grass
stage delay decreases the bare land value of a longleaf pine stand by about 6% annually. A longleaf pine stand with no grass
stage delay worth 2,500 per ha would be worth2,500 per ha would be worth 1,768 per ha with a 5-year grass stage delay. One could spend up to $478 per
ha to eliminate this 5-year grass stage delay and still break-even. 相似文献
12.
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
13.
Ten-year height data from three open-pollinated lodgepole pine progeny test trials were analysed in order to select individuals
for seed orchard establishment in the low and high elevation seed-planning units (TOLO and TOHI) of the new Thompson Okanagan
seed planning-zone in interior British Columbia, Canada. The total test population had about 35,000 individuals from 362 families
of 9 provenances and was divided into two portions, each serving as the base population for its appropriate seed-planning
unit. For each population, various genetic parameters were estimated and individual breeding values were predicted. Combined-site
estimates of individual, family, and within-family heritability ranged from 0.23 to 0.38, 0.77 to 0.84, and 0.17 to 0.29,
respectively. Estimated coefficients of type-b genetic correlation were greater than 0.81, indicating little G × E interaction
in this region. Provenance effects were large. Larch Hills and Inonoaklin River were the two superior provenances with an
expected gain of 13% and 10% in stem volume at rotation age of 60 years in TOLO. Individual breeding values was not uniformly
distributed among provenances and the top 100 individuals originated from 20 families in TOLO and 32 families in TOHI. Co-ancestry
among these individuals should not be a serious concern in seed orchard establishment as the predicted genetic loss due to
excessive inbreeding is only 1.06% in TOLO and 0.6% in TOHI. The status numbers of the two prospective seed orchards are 32
and 44, respectively, and both are well above the required minimum of 10 in British Columbia. Using unrelated clones for seed
orchard establishment may result in reduced optimum genetic gain and thus is not a favourable option. 相似文献
14.
Nabil E. El-Wakeil 《Journal of pest science》2007,80(1):29-34
The release of mass propagated egg parasitoids could be one option to control the lepidopteran pests. The efficiency of the
parasitoid Trichogramma evanescens (Westwood) reared on eggs of three different factitious hosts; Sitotroga cerealella, Ephestia kuehniella and Galleria mellonella was studied for controlling bollworm Helicoverpa armigera. Efficiency of Trichogramma was studied by measuring parasitism rates, emergence rates, longevity and sex ratio. Wasps reared from each source were tested
on the source host and on the target host, H. armigera under laboratory conditions. Rates of parasitism on H. armigera eggs, emergence rates of parasitoids and their longevity were the highest for wasps reared on H. armigera. Wasps reared on S. cerealella gave comparable rates. However, wasps from E. kuehniella gave the lower rates and G. mellonella gave the lowest ones. Parasitized eggs of H. armigera and S. cerealella produced more parasitoid females than eggs of E. kuehniella and G. mellonella. Results are discussed for magnifying efficiency of the parasitoid in controlling H. armigera in the field. 相似文献
15.
WANG Hui-mei ZU Yuan-gang 《林业研究》2007,18(4):316-318
UGPase gene related with wood cellulose synthesis was transferred into C. acuminata using the method of Agrobacte- rium-mediated genetic transformation, and an efficient transformation system was developed for C. acuminata on the basis of evaluations of several factors affecting Agrobacterium-mediated DNA transfer rate. The highest transformation rate was achieved when pre-cultttred leaf explants were infected with an Agrobacterium culture corresponding to OD600 (0.5) for 10 min, and cultured on explant regeneration medium for three days. The results of Southern hybridization showed that genomic DNA of the kanamycin-resistant shoots to an UGPase gene probe substantiated the integration of the transgene. Transformation efficiency (6%) was achieved under the optimized transformation procedure, This system should facilitate the introduction of important useful genes into C, acuminata. 相似文献
16.
Seed was collected from two habitat types (harsh/rocky and favorable/control) within five Balkan provenances. An experiment
was conducted to examine water uptake (grams water per gram of fresh seed) during 48 h after exposure to water. A second experiment
investigated the effect of simulated-drought conditions (4% sucrose solution) compared to non-drought conditions (distilled
water) on subsequent germination percentage. Seed from rocky habitats had less water uptake than those from control habitats
for three of the provenances. However, water uptake was not correlated with subsequent germination. Drought simulation decreased
germination but patterns for seed within each provenance were similar to germination under non-drought conditions. With the
exception of one provenance, seed from the rocky habitats had lower germination than seed from control habitats. The data
suggests some degree of adaptation to environmental conditions although variability was very high within each provenance’s
habitat types. This is of particular importance when considering potential impacts of climate change and the anticipated migration
of species due to changes in habitat. 相似文献
17.
A correlation between heterozygosity of genotypes and survival (fitness) was studied in eight natural populations of Pinus roxburghii through isozyme analysis using horizontal starch gel electrophoresis. Under each population, 20 mother trees of different
ages (30 to more than 100 years) were selected which were at least 50 m apart. From each tree, eight seeds were assayed for
eleven enzyme systems viz., Aconitase, Aspertate aminotransferase, Glutamate dehydrogenase, Isocitrate dehydrogenase, Leucine-amino
peptidase, Malate dehydrogenase, Menadione reductase, Phosphoglucose isomerase, Phosphoglucomutase, 6-Phosphogluconate dehydrogenase
and Shikimic acid dehdrogenase which were found to be encoded by 18 polymorphic loci. Genetic constitution of the mother trees
was determined by analysing endosperms and embryos separately. The number of alleles in the progeny (embryos) and the mother
trees varied from 38 to 42 and 34 to 37, respectively, in all the populations. Distribution of degree of heterozygosity and
fixation index for the progeny and the mother trees were calculated. The mother trees showed a substantial shift towards higher
degree of heterozygosity as compared to the progeny. Fixation index values were significantly higher and negative for the
mother trees as compared to the progeny, which revealed that heterozygosity was positively correlated with survival in P. roxburghii.
Application: Heterozygous geneotypes in tree species are shown to have better survival over homozygotes under diverse environmental
conditions. Every year, millions of Pinus roxburghii saplings are planted in India. However, the fact that survival is very low might possibly be due to inbred/homozygous plants
that suffer from fitness disadvantage. Our study indicates that heterozygotes have a better chance of survival under environmental
conditions. The use of heterozygotes should lead to effective establishments of Pinus roxburghii plantations. 相似文献
18.
Takeshi Taniguchi Shigenobu Tamai Norikazu Yamanaka Kazuyoshi Futai 《Journal of Forest Research》2007,12(5):350-357
Pine forests are declining because of pine wilt disease and Robinia pseudoacacia, a nitrogen-fixing species, is dominating coastal forests along the Sea of Japan. We examined the effects of R. pseudoacacia on the regeneration of a native pine species, Pinus thunbergii. Two 200 m2 plots were set up at the border of a P. thunbergii and R. pseudoacacia-dominated area in a coastal forest. We conducted monthly censuses of emergence, distribution and survival of pine seedlings
in the plots from May 2003 to December 2004. Light intensity and soil properties were also measured to analyze the relationships
between the survival of pine seedlings and environmental conditions using the Mantel test and the structural equation model.
Pinus thunbergii seedlings emerged in spring–early summer and in late autumn. Survival of pine seedlings in the R. pseudoacacia-dominated subplots was less than half that in the pine-dominated subplots. Survival of pine seedlings emerging in May 2003
was significantly reduced by the lower light intensity and higher soil nitrogen in R. pseudoacacia-dominated subplots. The tendency was the same for seedlings emerging from April to May 2004. We concluded that R. pseudoacacia reduced the intensity of light during the growing season and increased the nitrogen content of soil, which resulted in inhibition
of the natural regeneration of P. thunbergii. 相似文献
19.
To determine the effect of shade on morphology, growth and biomass allocation in Picea sitchensis, Larix × eurolepis and Thuja plicata, seedlings were grown in the open or under shadehouses providing 25%, 50% and 75% reductions of full-light for two growing
seasons. For most of the characteristics assessed there was no significant interaction between species and shade indicating
that the morphological responses to changing shade treatments were not species-dependent. After two growing seasons the mean
height increment for the three species was significantly greater in 25% (76.1 cm) and 50% shade (74.9 cm) than in the open
(69.5 cm). Root collar diameter increment, shoot, root and total biomass declined significantly with increasing shade while
the opposite was true for the height:diameter ratio. In both western red cedar and hybrid larch the shoot:root ratio was significantly
greater in the shade while in Sitka spruce this characteristic was not influenced by shade. While all species had significantly
greater specific shoot areas in 75% shade than in 0% shade, this trend was particularly pronounced in hybrid larch. In hybrid
larch and western red cedar, the normalised specific projected shoot area increased significantly with increasing shade. The
opposite trend was observed for Sitka spruce. We conclude that in the main the species studied demonstrated similar shade
acclimation responses despite their reported differences in shade tolerance. 相似文献
20.
Ana Cristina Gonçalves Anabela Afonso Dulce G. Pereira Anacleto Pinheiro 《Agroforestry Systems》2017,91(6):1019-1030
Most umbrella pine (Pinus pinea L.) stands are managed as agroforestry systems, whose main production is fruit, due to the edible and highly nutritious kernels, and are frequently associated to natural or seeded pastures and grazing. The stands have low density, in order to enhance crown growth and fruit production. Nevertheless, cone production, both with regard to number and weight, varies greatly between stands, trees and years. In this study were selected three agroforestry systems, representative of umbrella pine stands whose main production is fruit, and one stand representative of the timber production system, where fruit is the secondary production. It was evaluated the variability in cone production as a function of the tree’s diameter at breast height and crown diameter and the individual tree’s competition status. The results indicate that stands managed in agroforestry systems with lower competition and individuals with larger diameter at breast height and crown diameter tend to produce more and heavier cones per tree. The first two principal components of the principal component analysis explain 84 % of the variance in cone production, trees’ dimensions and competition index. Tree competition status has a negative impact on production per tree. 相似文献