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1.
Peter Höller 《Annals of Forest Science》2014,71(1):81-89
? Context
Snow gliding is a downhill motion of snow on the ground; observations have shown gliding to be possible not only on open slopes but also in forest stands. Larch stands, with their low canopy density and open forest structure with clearings and gaps, are particularly prone to high glide rates. Snow gliding may have negative effects on juvenescent trees which can be damaged by extraction from the ground.? Aim
The goal of this study was to determine whether snow gliding depends on forest cover (canopy) and size of clearings.? Methods
Snow gliding was measured during eight winter periods at six measuring positions (ranging from ‘dense forest’ to ‘open slope’) in and beside a larch stand in the Stubai Valley, Tyrol, Austria.? Results
The results showed that gliding is strongly influenced by forest cover. Snow gliding increases with decreasing canopy density. The difference between the six measuring positions was highly significant (p?<?0.005).? Conclusion
The identified glide cracks on at least two measuring positions, indicating extreme glide rates and, therefore, strong negative effects on juvenescent trees. To prevent glide rates of a magnitude such as this requires a mature forest with at least 300 stems/ha. 相似文献2.
? Context
The knowledge of how shrub–seedling interactions vary with summer drought, canopy opening, and tree species is crucial for adapting forest management to climate change.? Aims
The aim of this study was to assess variation in shrub–oak recruitment associations along a south–north drought climate gradient and between two levels of canopy cover in coastal dune forest communities in a climate change-adapted forest management perspective.? Material and methods
Mapped data of associational patterns of seedlings of three oak species with interspecific pooled shrubs were analyzed using a bivariate pair correlation function in 10 (0.315 ha) regeneration plots located in forest and recent gap sites along the climate gradient. An index of association strength was calculated in each plot and plotted against a summer moisture index.? Results
The association strength increased with increasing summer drought from wet south to dry north and from closed forests to gaps.? Conclusion
Consistent with facilitation theory, our results suggest that climate change may shift associational patterns in coastal dune forest communities towards more positive associations, in particular in canopy gaps. In a perspective of climate change, foresters may need to conserve understory shrubs in gaps in order to promote oak species regeneration. 相似文献3.
Context
The dipterocarp forests in the Central Highland of Vietnam are threatened by overharvesting. In addition, wildfires frequently affect their dynamics. Sustainable management of this unique forest type is of important concern.Aims
This study aims at providing a first set of operational information for forest management with a model-based approach. Specifically, we (a) evaluate selected cutting regimes with focus on maximum sustainable yield, (b) explore transformation times from a given to a desired forest state, and (c) preliminarily assess wildfire effects on yield.Methods
A size class model was developed as a tool to address these issues. Various diameter distributions defined by the q factor concept were used as possible desired equilibrium states to be assessed.Results
Maximum yields were estimated between 3.9 and 2.7?m3?ha?1?year?1, depending on site quality. Based on data from overharvested stands, time for reaching desired equilibria ranged between 20 and 60?years. In stands with frequent severe wildfires, the long-term yield may decrease by 40%.Conclusions
Our results suggest the model being an effective tool for simulating effects of treatment alternatives. We conclude that, despite a poor information basis, it is necessary to develop and refine such models for supporting sustainable forest management in Vietnam. 相似文献4.
? Context
Models for predictions of soil compaction following forest traffic represent important decision tools for forest managers in order to choose the best management practices for preserving soil physical quality. In agricultural soil compaction research, analytical models are widely used for this purpose.? Aims
Our objective was to assess the ability of an analytical model to predict forest soil compaction under forwarder traffic.? Methods
We used the results from two experimental sites set up in north-eastern France in 2007 and 2008 to compare simulations using the SoilFlex model with observed bulk density following forwarder traffic.? Results
The best model-based predictions were found when considering the mean initial soil conditions and an increased rebound parameter in the upper soil layers (0–10 cm) in comparison to the deeper layers (10–50 cm). The need to increase the rebound parameter in the soil surface layer to improve model accuracy was attributed to a large soil organic matter content in the uppermost layers of forest soils. For the site where initial soil mechanical parameters were measured as a function of soil bulk density and water content, the model performance was good, with a root mean square error (RMSE) of 0.06. The model performed poorer (RMSE of 0.11), especially for the surface soil layer, for the second site that was wetter at the time of traffic and where soil mechanical properties were not measured but estimated by means of pedo-transfer functions.? Conclusions
SoilFlex was found to yield satisfactory predictions and could help forest managers estimate the risk of compaction and to select the most appropriate machinery for given soil conditions in order to preserve the soil from physical degradation during traffic in forest ecosystems. However, our results emphasise the need for research on soil mechanical properties of forest soils, in particular on the role of soil organic matter and roots on soil compressive properties. 相似文献5.
? Context
Two-thirds of Britain’s forest area is privately owned. Thus, understanding private forest owners and managers, and their attitudes to uncertainty and change, is essential for the success of climate change adaptation policies.? Aim
The aims of this study are to (1) assess how beliefs in climate change in the private sector have influenced forest management practices; (2) identify constraints related to changes in species choice and silvicultural systems; (3) analyse the implications for implementing climate change policy in forestry.? Method
Semi-structured interviews with key informants who provide advice to, or manage woodlands in, the private forest sector in north Wales.? Results
Woodland managers and some advisers are not generally convinced of a need to adapt. They feel the future is uncertain, more usually in relation to tree disease than to climate change itself. Species choice is the principle focus of adaptation activities and reveals a deep divide in opinion. Commercial advisors look to new exotics but are inhibited by absence of markets, while small-scale owners rely more on native genetic diversity.? Conclusions
Findings that are likely to apply widely include: the influential role of forest agents in forest management decisions including species choice; lack of confidence in climate change predictions, and in markets; more immediate concerns about tree pests and diseases; demand for leadership from the public sector, and for engagement amongst the private sector. Further research is needed across a wider area to test the variability in relationship between attitudes and behaviours, and local conditions including climate change predictions. 相似文献6.
Lichao Wu Jie Liu Atsushi Takashima Keiichi Ishigaki Shin Watanabe 《Annals of Forest Science》2013,70(5):535-543
?Context
Selective logging followed by natural regeneration is rarely employed for restocking subtropical evergreen broad-leaved forests in East Asia compared with the use of clear-cutting.?Aims
To clarify the succession of these forests, the effects of selective logging on stand structure, species diversity, and community similarity were studied in a mature and regenerating forest in Okinawa, Japan.?Methods
Four study plots were established, and trees ≥1.2 m height were identified by species name, tree height, and diameter at breast height.?Results
The results showed that the species composition of regenerating forest was similar to mature forest; however, the former had a greater species density and Shannon–Wiener index than the latter. Castanopsis sieboldii and Distylium racemosum, the predominant trees in the mature forest, continued to dominate the regenerating forest, with a broad layer distribution. High Sørensen and Jaccard community similarity indices for mature and regenerating forest indicated that the regeneration occurred in a progressive succession.?Conclusion
The similar species composition and stand structure for both mature and regenerating forest, and the higher species diversity for the latter, provided no evidence of forest degeneration and suggested that the regenerating forest may develop into a stand similar to preselective logging forest. 相似文献7.
? Context
The Kyoto Protocol allows the use of domestic forest carbon sequestration to offset emissions to a limited degree, while bioenergy as an unlimited emission reduction option receives substantial financial support in many countries.? Aim
The primary objective of this study was to analyze (1) whether these limits on forest carbon sequestration would be binding, thereby leading to inefficient mitigation, and (2) the total potential effect of the protocol on the greenhouse gas (GHG) fluxes in the forest sector.? Methods
A partial equilibrium model of the Norwegian forest sector was used to quantify the GHG fluxes in a base scenario with no climate policy, a Kyoto Protocol policy (KP policy), and a policy with no cap on forest carbon sequestration (FC policy), assuming that the policies apply the rest of the century.? Results
Carbon offsets are higher under the KP policy than in the base scenario and likewise higher than under the FC policy in the short run, but the KP policy fails to utilize the forest carbon sequestration potential in the long run as it provides considerably less incentives to invest in forestry than the FC policy.? Conclusion
The KP increases the Norwegian forest sector’s climate change mitigation compared to no climate policy but less in the long run than a carbon policy with no cap on forest carbon credits. 相似文献8.
Christopher Reyer Petra Lasch-Born Felicitas Suckow Martin Gutsch Aline Murawski Tobias Pilz 《Annals of Forest Science》2014,71(2):211-225
? Context
Projecting changes in forest productivity in Europe is crucial for adapting forest management to changing environmental conditions.? Aims
The objective of this paper is to project forest productivity changes under different climate change scenarios at a large number of sites in Europe with a stand-scale process-based model.? Methods
We applied the process-based forest growth model 4C at 132 typical forest sites of important European tree species in ten environmental zones using climate change scenarios from three different climate models and two different assumptions about CO2 effects on productivity.? Results
This paper shows that future forest productivity will be affected by climate change and that these effects depend strongly on the climate scenario used and the persistence of CO2 effects. We find that productivity increases in Northern Europe, increases or decreases in Central Europe, and decreases in Southern Europe. This geographical pattern is mirrored by the responses of the individual tree species. The productivity of Scots pine and Norway spruce, mostly located in central and northern Europe, increases while the productivity of Common beech and oak in southern regions decreases. It is important to note that we consider the physiological response to climate change excluding disturbances or management.? Conclusions
Different climate change scenarios and assumptions about the persistence of CO2 effects lead to uncertain projections of future forest productivity. These uncertainties need to be integrated into forest management planning and adaptation of forest management to climate change using adaptive management frameworks. 相似文献9.
Variation in biomass expansion factors for China’s forests in relation to forest type, climate, and stand development 总被引：1，自引：0，他引：1
Yunjian Luo Xiaoke Wang Xiaoquan Zhang Yin Ren Hendrik Poorter 《Annals of Forest Science》2013,70(6):589-599
? Context
Biomass expansion factors (BEFs, defined as the ratios of tree component biomass (branch, leaf, aboveground section, root, and whole) to stem biomass) are important parameters for quantifying forest biomass and carbon stock. However, little information is available about possible causes of the variability in BEFs at large scales.? Aims
We examined whether and how BEFs vary with forest types, climate (mean annual temperature, MAT; mean annual precipitation, MAP), and stand development (stand age and size) at the national scale for China.? Method
Using our compiled biomass dataset, we calculated values for BEFs and explored their relationships to forest types, climate, and stand development.? Results
BEFs varied greatly across forest types and functional groups. They were significantly related to climate and stand development (especially tree height). However, the relationships between BEFs and MAT and MAP were generally different in deciduous forests and evergreen forests, and BEF–climate relationships were weaker in deciduous forests than in evergreen forests and pine forests.? Conclusion
To reduce uncertainties induced by BEFs in estimates of forest biomass and carbon stock, values for BEFs should be applied for a specified forest, and BEF functions with influencing factors (e.g., tree height and climate) should be developed as predictor variables for the specified forest. 相似文献10.
Introduction and statement of the research questions
Gap dynamics have been widely studied in forests of Abies spp. from temperate and boreal regions. The local microclimate and competition for light have been identified as the main factors controlling changes in species composition and canopy structure, however little is known on dynamics of such forests in Mediterranean.Experimental design and aims
We studied forest structure and dynamics of Abies pinsapo stands in southern Spain, in contrasting habitats and successional status. In addition past regeneration patterns and their relationship to canopy structure, disturbances and forest-use history were investigated.Results
Stands structure attributes were within the range described for temperate conifer biomes. The age structure revealed two main cohorts comprised of a few > 100 year-old trees and abundant younger trees established in a single recruitment event after the stands were protected in the 1950s. Initial growth-rate analyses indicated that A. pinsapo regenerated mainly in small canopy gaps, while only 15% recruited from the forest understorey. For the last ten years, basal area increment was lower than 10 cm2 y?1 in 91% of studied trees and growth rate differences between trees narrowed.Conclusion
Stand dynamics in A. pinsapo forests maintain general features of temperate fir forests. Tree establishment over time and current stand structure fit to known changes in forest use. Widespread growth decline trends might be linked to stand stagnation and global warming. 相似文献11.
Cristina Pascual Luis G. Garc��a-Montero Lara A. Arroyo Antonio Garc��a-Abril 《Annals of Forest Science》2013,70(1):87-99
Context
Forest structure characterisation approaches using LiDAR data and object-based image analysis remain scarce to forestry agencies as these automated procedures usually require the use of expensive software and highly skilled analysts. The integration of forest expert opinion into semi-automated approaches would simplify the access of forest managers to new technologies and would allow the incorporation of personal experience and the introduction of specific forest management criteria.Aim
The aim of this study is to explore new alternatives to a previously published automated approach based on LiDAR data and object-based image analysis.Methods
We compare four approaches, ranging from null to high incorporation of expert opinion and from fully automated to fully manual. These four approaches consist of three stages: (1) forest stand identification from LiDAR models, (2) forest stand classification into forest structure classes (manual and based on cluster analysis), and (3) validation.Results
Quantitative attributes for validation (i.e. hypsographs and percentiles) provided slightly lower degree of separability for forest structure classes, in the mixed procedures with increasing incorporation of expert opinion than for the fully automated approach.Conclusions
The new mixed approaches proposed are comparable to the automated procedures for the characterisation of forest structure in heterogeneous pine forest stands. They also offer additional advantages: (1) they make it possible to give a specific management focus and (2) they provide accessibility by the forest managers to the source of LiDAR information. 相似文献12.
13.
Miloš Ivković Washington Gapare Harry Wu Sergio Espinoza Philippe Rozenberg 《Annals of Forest Science》2013,70(5):525-534
? Context
The correlation between tree ring width and density and short-term climate fluctuations may be a useful tool for predicting response of wood formation process to long-term climate change.? Aims
This study examined these correlations for different radiata pine genotypes and aimed at detecting potential genotype by climate interactions.? Methods
Four data sets comprising ring width and density of half- and full-sib radiata pine families were used. Correlations with climate variables were examined, after the extraction of the effect of cambial age.? Results
Cambial age explained the highest proportion of the ring to ring variation in all variables. Calendar year and year by family interaction explained a smaller but significant proportion of the variation. Rainfall had a positive correlation with ring width and, depending on test site, either a negative or positive correlation with ring density. Correlations between temperature during growing season and ring density were generally negative.? Conclusion
Climate variables that influence ring width and wood density can be identified from ring profiles, after removing the cambial age effect. Families can be selected that consistently show desirable response to climate features expected to become prevalent as a result of climate change. 相似文献14.
Variation of wood color parameters of Tectona grandis and its relationship with physical environmental factors 总被引：1，自引：0，他引：1
? Context
Teak??s wood color is considered an important attribute in the marketing phase and it has been influenced by environmental setting, stand conditions and management, plant genetic source, and age. However, there is a lack of understanding about how the environmental factors might affect the teak??s wood color planted in short-rotation forest plantations.? Aims
The aim of this study is to understand the relationship, gathered from generated information, between edaphic and climatic variables and their effects in the wood color variation of Tectona grandis from trees in forest plantations.? Methods
Twenty-two plots were grouped in five cluster sites that shared similar climatic and soil conditions. Data about soil??s physical?Cchemical properties and climatic variables were collected and analyzed. Representative trees were harvested next to each plot in order to obtain a wood sample per tree at a diameter breast height. Wood color was measured using standardized CIELab??s chromaticity system.? Results
After comparing the wood change color index (?E*) in the five studied clusters, it was found that heartwood produced from drier and fertile sites had more yellowish-brown color. The heartwood b* color index resulted with significant correlations (R?>?0.5, P?<?0.05) among nine climatic and eight edaphic variables.? Conclusion
It was concluded that climatic variables should be considered as the first-order causal variables to explain wood color variation. Hence, darker b* wood color was associated with dry climates; also, with deeper and fertile sites. 相似文献15.
Context
Implementing nature-based silviculture requires understanding the structural and compositional changes that occur in forested stands under known disturbance types and intensities.Aims
The objectives were to assess the (a) resistance of hardwood forests to change, (b) their trajectory of recovery following disturbance, and (c) how closely resulting forests resemble original forests.Methods
We characterized tree structure and composition at three points in time (pre-disturbance, 1-year post-disturbance, and ～15 years following disturbance) along a harvesting disturbance gradient created by removing trees in different forest canopy strata.Results
Significant differences to pre-disturbance conditions were noted immediately post-harvest for tree basal area, density, species richness, and tree species composition; treatment differences were observed for all parameters except diversity. Plots exposed to the least extreme harvesting disturbances (cutting small and intermediate trees) had returned to pre-disturbance conditions for most parameters after 15 years, while the most extreme harvesting disturbance (cutting large trees) had not yet recovered.Conclusions
Although not initially resistant, Central Appalachian eastern hardwoods are fairly resilient to the removal of trees in the subcanopy or a mixture of the subcanopy and canopy; only the removal of solely canopy trees (i.e., high grading) and complete removal (i.e., clearcutting) appear to impose harvesting disturbances to which these forests may not be resilient. 相似文献16.
Sergio de-Miguel Timo Pukkala Nabil Assaf Zuheir Shater 《Annals of Forest Science》2014,71(1):101-112
? Context
Biomass prediction is important when dealing for instance with carbon sequestration, wildfire modeling, or bioenergy supply. Although allometric models based on destructive sampling provide accurate estimates, alternative species-specific equations often yield considerably different biomass predictions. An important source of intra-specific variability remains unexplained.? Aims
The aims of the study were to inspect and assess intra-specific differences in aboveground biomass of Pinus brutia Ten. and to fill the gap in knowledge on biomass prediction for this species.? Methods
Two hundred one trees between 2.3 and 55.8 cm in diameter at breast height were sampled throughout the eastern- and southernmost natural distribution area of P. brutia, in Middle East, where it forms different stand structures. Allometric equations were fitted separately for two countries. The differences in biomass prediction at tree, stand, and forest level were analyzed. The effect of stand structure and past forest management was discussed.? Results
Between-country differences in total aboveground biomass were not large. However, differences in biomass stock were large when tree components were analyzed separately. Trees had higher stem biomass and lower crown biomass in dense even-aged stands than in more uneven-aged and sparse stands.? Conclusion
Biomass and carbon predictions could be improved by taking into account stand structure in biomass models. 相似文献17.
Andreas Rais Werner Poschenrieder Hans Pretzsch Jan-Willem G. van de Kuilen 《Annals of Forest Science》2014,71(5):617-626
? Context
Mechanical wood properties are increasingly relevant for structural applications and are influenced by growing space availability. Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) has an increasing market share in Europe and is mainly processed to sawn timber.? Aim
A sample of 164 thinning trees was taken from two Douglas-fir long-term forestry research plots in Germany. The end-use quality of about 2,000 side and center boards was analyzed as a function of initial plant density (1,000, 2,000, and 4,000 trees per hectare) and log position within the stem.? Methods
Sawn timber quality was described by knottiness, density, modulus of elasticity, and strength. Explanatory parameters were radial position, longitudinal position, and initial plant density. All boards were strength graded visually and by the grading machine GoldenEye-706 using both X-rays for detecting densities and size as well as position of knots and laser interferometry for detecting eigenfrequency (DIN 4074, DIN 2012; EN 14081-2, CEN 2010).? Results
High plant density led to better mechanical sawn timber quality. Significant differences were especially observed between 1,000 and 2,000 trees per hectare. The yield of machine strength-graded center boards of strength class C24 increased from 50 to 89 % at low and high initial plant density, respectively.? Conclusion
Foresters are able to improve end-product quality by controlling planting density in particular. The roundwood price that foresters get should be based on the proportion of higher strength classes within logs to give incentives for a more quality-oriented forest management. 相似文献18.
? Context
The rising demand of energy wood for heating purposes in Germany leads to concerns regarding the overexploitation of forests. A major aspect is the impact of whole-tree harvesting on long-term productivity of forest soils.? Aims
This study aimed to analyze the effects of nutrient removal on productivity using the historically prevalent practice of litter raking. Since there is a lack of controlled whole-tree harvesting experiments in Germany, we used litter raking as a surrogate management practice entailing the removal of nutrients from forest stands.? Methods
We used three sites with documented litter raking to analyze the effects of nutrient removal on productivity using dendroecological methods: two recent litter removal experiments in two Scots pine stands (Siegenburg and Burglengenfeld) and one oak stand (Eichhall) with documented historic litter raking. Basal area increment (BAI) and tree-ring characteristics were compared between periods with litter raking and the preceding periods for both treatment and control plots.? Results
For the two Scots pine sites with a relatively short litter raking period, no effects of litter raking on BAI could be ascribed to nutrient removal. On the oak site with a longer history of litter utilization, the loss in BAI due to litter raking amounts to 22 % during the period with active raking and to still 17 % in the recovery period.? Conclusions
These results contribute to the still very limited understanding about the impact of whole-tree harvesting on forest productivity in Germany by laying down an upper limit of possible effects due to nutrient removal, as nutrient loss by litter raking tends to be higher than nutrient loss by whole-tree harvesting. 相似文献19.
Holger Wernsd?rfer Antoine Colin Jean-Daniel Bontemps Hélène Chevalier Gér?me Pignard Sylvain Caurla Jean-Michel Leban Jean-Christophe Hervé Meriem Fournier 《Annals of Forest Science》2012,69(7):829-844
? Context
Forest resource projections are required as part of an appropriate framework for sustainable forest management. Suitable large-scale projection models are usually based on national forest inventory (NFI) data. However, sound projections are difficult to make for heterogeneous resources as they vary greatly with respect to the factors that are assumed to drive forest dynamics on a large spatial scale, e.g. geographically varying growth conditions (here represented by NFI regions), tree species composition (here broadleaf-dominated, conifer-dominated and broadleaf-conifer mixed stands) and stand structure (here high forest, coppice forest and high-coppice forest mixture).? Question and objective
Our question was how does the variance of forest dynamics parameters (i.e. growth, felling and mortality, and recruitment processes) and that of 20-year forest resource projections partition between these factors (NFI region, tree species composition and stand structure), including their interactions. Our objective was to capitalise on the suitability of an existing multi-strata, diameter class matrix model for the purposes of making projections for the highly heterogeneous French forest resource.? Methods
The model was newly calibrated for the entire territory of metropolitan France based on most recent NFI data, i.e. for years 2006?C2008. The forest resource was divided into strata by crossing the factors NFI region, tree species composition and stand structure. The variance partitioning of the parameters and projections was assessed based on a model sensitivity analysis.? Results
Growth, felling and mortality varied mainly with NFI region and species composition. Recruitment varied mainly with NFI region and stand structure. All three factors caused variations in resource projections, but with unequal intensities. Factor impacts included first order and interaction effects.? Conclusions
We found, by considering both first order and interaction effects, that NFI region, species composition and stand structure are ecologically relevant factors that jointly drive the dynamics of a heterogeneous forest resource. Their impacts, in our study, varied depending on the forest dynamics process under consideration. Recruitment would appear to have a particularly great impact on resource changes over time. 相似文献20.