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Amalesh Dhar Lael Parrott Scott Heckbert 《Scandinavian Journal of Forest Research》2018,33(8):741-755
Insect outbreaks are natural phenomena that play a critical role in the development, senescence, and rebirth of forests. However, the damage caused by large-scale epidemics can have landscape scale consequences that are often poorly understood. The recent mountain pine beetle (MPB) outbreak in Canada has impacted a record >18.5 million hectares of pine forests, placing forest values at risk and significantly impacting forest-dependent communities within the region. To assess this impact, an ecosystem service-based approach was applied. Based on land cover information and monitoring data, four ecosystem services were assessed and mapped: merchantable timber, water provisioning, aboveground carbon storage, and vegetation diversity (supporting habitat). Timber is the most impacted provisioning ecosystem service followed by water provisioning, with peak stream flow in affected watersheds being positively related to mortality percent. Effects on carbon storage are substantial, with 20% of total timber aboveground carbon in dead pine trees. These effects may be mitigated, however, by the growth response of residual live trees and forest regeneration. The potential vegetation diversity showed a positive response to MPB-caused tree mortality. The results of our study may help with setting management priorities in response to large-scale biotic damage in forests in British Columbia and elsewhere. 相似文献
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Losses through reduced growth or mortality attributable to pests, diseases, and abiotic disturbances are generally less in intensively managed, planted forests than in natural forests. Among plantation forests, the most healthy forests are those of exotic species growing a long way from their native range (e.g., Pinus radiata D. Don in New Zealand) and the least healthy ones are those of indigenous species (e.g., Eucalyptus nitens (Deane & Maiden) Maiden in Tasmania). The better health of plantations is a reflection of the generally good growing conditions, the proper matching of site to species that is possible in artificial culture and in the case of exotic species, the freedom from the many pests and diseases present in the native habitat of exotics. 相似文献
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Relationships between advance regeneration of four tree species (red maple (Acer rubrum L.), white oak (Quercus alba L.), chestnut oak (Q. montana Willd.) and northern red oak (Q. rubra L.)) and biotic (non-tree vegetation and canopy composition) and abiotic (soil series and topographic variables) factors were investigated in 52, mature mixed-oak stands in the central Appalachians. Aggregate height was used as a composite measure of regeneration abundance. Analyses were carried out separately for two physiographic provinces. Associations with tree regeneration were found for all biotic and abiotic factors both in partial models and full models. Red maple was abundant on most of the sites, but high red maple abundance was commonly associated with wet north-facing slopes with little or no cover of mountain-laurel (Kalmia latifolia L.) and hay-scented fern (Dennstaedtia punctilobula (Michx.) Moore). Regeneration of the three oak species was greatly favored by the abundance of overstory trees of their own kind. White oak regeneration was most abundant on south-facing, gentle, lower slopes with soils in the Buchanan series. Chestnut oak regeneration was more common on south-facing, steep upper slopes with stony soils. There was a positive association between chestnut oak and huckleberry (Gaylussacia baccata (Wangh.) Koch) cover classes. Northern red oak was more abundant on north-facing wet sites with Hazleton soil, and was associated with low occurrence of mountain-laurel and hay-scented fern. 相似文献
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Arne Nothdurft Joachim Saborowski Johannes Breidenbach 《European Journal of Forest Research》2009,128(3):241-251
This study aims at the development of a model to predict forest stand variables in management units (stands) from sample plot
inventory data. For this purpose we apply a non-parametric most similar neighbour (MSN) approach. The study area is the municipal
forest of Waldkirch, 13 km north-east of Freiburg, Germany, which comprises 328 forest stands and 834 sample plots. Low-resolution
laser scanning data, classification variables as well rough estimations from the forest management planning serve as auxiliary
variables. In order to avoid common problems of k-NN-approaches caused by asymmetry at the boundaries of the regression spaces and distorted distributions, forest stands are
tessellated into subunits with an area approximately equivalent to an inventory sample plot. For each subunit only the one
nearest neighbour is consulted. Predictions for target variables in stands are obtained by averaging the predictions for all
subunits. After formulating a random parameter model with variance components, we calibrate the prior predictions by means
of sample plot data within the forest stands via BLUPs (best linear unbiased predictors). Based on bootstrap simulations,
prediction errors for most management units finally prove to be smaller than the design-based sampling error of the mean.
The calibration approach shows superiority compared with pure non-parametric MSN predictions. 相似文献
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Evaluation of carbon sequestration and thinning regimes within the optimization framework for forest stand management 总被引:2,自引:0,他引:2
Due to the urgent demand for thinning in planted forests and the tend towards sustainable forest resource management, the
forest stand age class eligible for the thinning subsidy in Japan was expanded during the period from 2000 to 2004. Currently,
further expansion is under consideration in line with meeting the Kyoto Protocol target of carbon sequestration. In this paper,
we conducted evaluation analyses of carbon sequestration and subsidy effects within the optimization framework for the forest
stand management. The optimal forest stand management model called Dynamic Programming model for Kyushu Stand Simulator (DP-KYSS)
was utilized for the analysis of the target sugi (Cryptomeria japonia) forest stand in the Kyushu region, Japan. Our results showed that the thinning subsidy was effective to stimulate thinning
activities at the eligible age class for the subsidy, and that 20% of the current or proposed payment was appropriate to give
an incentive to forest owners for conducting the same optimal thinning regime. The amount of carbon sequestered in remaining
trees at final harvest was not always shown to increase over time. Depending upon the subsidy condition, it could decrease.
The average annual amount of carbon sequestered under no subsidy showed its maximum at age 35, while under the other subsidy
conditions, it was shortened to age 25. The net present value of cost per unit carbon loss associated with subsidy became
the highest for the rotation age of 35 years for all subsidy policies considered here. 相似文献
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比较分析了22年生杉木集约林及一般林的生长状况及生物量差异,研究结果表明:不同经营模式对杉木林分平均胸径、平均树高、单位面积蓄积量的生长存在着极显著的影响;集约林分的平均树高、平均胸径、单位面积蓄积量及单株总生物量分别高于对比的一般林分35.34%、34.23%、27.26%及27.83%。 相似文献
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《Forest Ecosystems》2015,(3)
Background: Forest management faces a climate induced shift in growth potential and increasing current and emerging new risks. Vulnerability analysis provides decision support based on projections of natural resources taking risks and uncertainties into account. In this paper we(1) characterize differences in forest dynamics under three management scenarios,(2) analyse the effects of the three scenarios on two risk factors, windthrow and drought stress, and(3) quantify the effects and the amount of uncertainty arising from climate projections on height increment and drought stress.Methods: In four regions in northern Germany, we apply three contrasting management scenarios and project forest development under climate change until 2070. Three climate runs(minimum, median, maximum) based on the emission scenario RCP 8.5 control the site-sensitive forest growth functions. The minimum and maximum climate run define the range of prospective climate development.Results: The projections of different management regimes until 2070 show the diverging medium-term effects of thinnings and harvests and long-term effects of species conversion on a regional scale. Examples of windthrow vulnerability and drought stress reveal how adaptation measures depend on the applied management path and the decision-maker's risk attitude. Uncertainty analysis shows the increasing variability of drought risk projections with time. The effect of climate projections on height growth are quantified and uncertainty analysis reveals that height growth of young trees is dominated by the age-trend whereas the climate signal in height increment of older trees is decisive.Conclusions: Drought risk is a serious issue in the eastern regions independent of the applied silvicultural scenario,but adaptation measures are limited as the proportion of the most drought tolerant species Scots pine is already high. Windthrow risk is no serious overall threat in any region, but adequate counter-measures such as species conversion, species mixture or reduction of target diameter can be taken. This simulation study of three silvicultural scenarios and three climate runs spans a decision space of potential forest development to be used for decision making. Which adaptation measures to counteract climate induced risks and uncertainty are to be taken is,however, a matter of individual risk attitude. 相似文献
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M. P. Eichhorn 《Journal of Forest Research》2010,15(6):391-397
Many populations have a bimodal size distribution, even when composed of a single cohort. In developing forest stands, this
pattern is usually attributed to asymmetric competition at canopy closure among trees which have access to the upper canopy
and those which have failed to reach it. Nevertheless, alternative explanations for bimodality exist, and in sessile organisms
spatial pattern analysis can be used to compare their predictions. A 0.25-ha plot was created in a maturing stand of Asiatic
white birch (Betula platyphylla Sukacz.) in Central Kamchatka. All stems >1 cm diameter at breast height (DBH) were fully mapped. Mark correlation analysis
revealed size compensation among stems up to 3.5 m apart, providing evidence that competition affected the distribution of
stem sizes. The spatial pattern of trees was analysed using the pair correlation function g(r). Large trees (>20 cm DBH) had a dispersed distribution to which a Strauss soft-core Gibbs process model was fitted. This
suggested that large trees interacted at scales up to 4.16 m. Small trees (1–20 cm DBH) were distributed randomly, but a cross-pair
correlation analysis revealed a greater likelihood of occurrence beginning at 4.3 m from large trees, closely matching the
modelled interaction distance. These results are consistent with the hypothesis that asymmetric competition is structuring
this bimodal cohort of trees: large stems tend towards a dispersed pattern, exerting competitive effects at scales up to approximately
4 m, whereas smaller stems are more commonly found in the interstices within the pattern of large trees. 相似文献
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林火与森林虫害关系的研究概况 总被引:4,自引:0,他引:4
简要介绍了国内外关于林火与森林虫害关系研究的概况及已取得的一些成果,提出了目前研究所存在的问题,并对未来的研究发展方向作了展望。 相似文献
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伞伐更新法对赫卡尼亚(Hyrcanian)森林系统中森林再生和林分结构的影响 总被引:1,自引:0,他引:1
Mohammad Reza Pourmajidian Hamid Jalilvand Asghar Fallah Seyed Ataollah Hosseini Aidin Parsakhoo Amin Vosoughian Ali Rahmani 《林业研究》2010,21(3):265-272
研究伞伐更新法对赫卡尼亚森林系统中森林再生和林分结构的影响。在伊朗北部优势种为山毛榉(Fagus orientalisLipsky)的硬木林,采取伞伐更新法和非伞伐更新法方法设计实验区。结果表明,在山毛榉(F orientalis Lipsky)林中采用伞伐更新法处理,明显影响林下草本植物种的频度和密度。伞伐更新法处理后,林堇菜(Viola silvestris Lam.)、车叶草(Asperula odorata L.)、苔草(Carex spp.)和悬钩子(Rubushyrcanus Juz)的种频度明显增加。在对照区,树种的胸高直径(57.50±2.15cm)大于被处理区(50.67±1.88cm)的树种的胸高直径(50.67±1.88 cm),但对照区和处理区的树种的高度值相似。在1995-2005年间,波斯铁木(Parrotia persica)苗木数量增加到13.2%,而山毛榉(F orientalis)和欧洲鹅耳枥(Carpinus betulus)的苗木数量却明显减少。总之,应该利用其它育林方法,如,带状择伐作业,而不是伞伐更新法培育赫卡尼亚森林中山毛榉林。 相似文献
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Snow/wind damage is one of the important natural disturbances in forest ecosystems, especially in a montane secondary forest. However, the effects of snow/wind damage remain unclear which affects the management of these forests. Therefore, we investigated the responses of species, individual tree traits and stand structure to snow/wind damage in a montane secondary forest. Results show that, amongst the canopy trees, Betula costata exhibited the most uprooting, bending and overall damage ratio (the number of damaged stems to the total number of stems in a plot); Quercus mongolica showed the highest breakage ratio and Fraxinus mandshurica and Juglans mandshurica the least overall damage ratios. Among the subcanopy trees, Carpinus cordata, Acer mono, Acer tegmentosum and Acer pseudo-sieboldianum showed the least uprooting and breakage, and the most bending damage. A. pseudo-sieboldianum demonstrated the lowest breakage and highest bending damage ratios. These findings indicate that different species have various sensitivities to snow/wind damage. Larger trees (taller, wider crowns) tend to break and become uprooted, while smaller trees are bent or remain undamaged, suggesting that tree characteristics significantly influence the types of damage from snow and wind. Stands of Q. mongolica and B. costata had the highest damage ratios, whereas A. pseudo-sieboldianum had the lowest snapping ratio. In summary, the severity and type of snow/wind damage are related to individual tree attributes and stand-level characteristics. Therefore, selection of suitable species (e.g., shorter, smaller with deep root systems, hard wood, bending resistance and compression resistance) and appropriate thinning are recommended for planting in the montane secondary forests. 相似文献
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《Forest Ecology and Management》1997,95(1):35-43
We investigated stand dynamics of a mixed coppice forest of shade-tolerant and intermediate species, Fagus crenata Bl. and Quercus crispula Bl., in five stands with canopy-stem densities from 420 to 1320 ha−1 (estimated stand age: 37–62 years). The mean basal area (BA), exposed-crown area (ECA) and crown depth (CD) per stem were significantly larger in F. crenata in the three lower density plots. Also Q. crispula had considerably less overtopped stems in the two lower density plots. The mean annual BA increments of the two species were similar in the earlier 20 years; however, in the most recent 5 years, F. crenata had a higher relative growth rate for basal area (RGRBA) than Q. crispula. The most critical variable of the RGRBA was the ECA for F. crenata and the relative height (RH) for Q. crispula. We predict that dominance of F. crenata will gradually increase over that of Q. crispula as stands mature. This seems to be caused by lower shade-tolerance despite the similar initial growth rates of Q. crispula compared with F. crenata. 相似文献
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Atsushi Yoshimoto 《Journal of Forest Research》2002,7(2):81-90
In this paper, a stochastic control model is constructed by incorporating geometric Brownian motion to capture uncertain price
dynamics into a one-stage and two-state stochastic dynamic programming model. The proposed model is designed to search for
optimal harvest timing under price uncertainty without considering other forestry operations,e.g., thinning. We consider the option of abandoning forest management for an alternative use of forest land besides replantation.
Our experimental analysis shows that the optimal harvest timing under stochastic log prices is delayed when a price level
is crucially low for maintaining the management. It is also shown that when the current log price is sufficiently high, the
optimal harvest timing derived from both the stochastic and deterministic approach becomes the same. With a downward trend
of stochastic price dynamics, the optimal harvest timing tends to be hastened overall. This is because of the depreciation
effect on the future return, which stimulates harvesting in an earlier period.
This research was supported by a Grant-in-Aid for Scientific Research (No.11660155) from the Ministry of Education, Culture,
Sports, Science and Technology of Japan. 相似文献