共查询到20条相似文献,搜索用时 46 毫秒
1.
? 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2.
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3.
? 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4.
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5.
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6.
? 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7.
Gauthier Ligot Thibaut Gheysen François Lehaire Jacques Hébert Alain Licoppe Philippe Lejeune Yves Brostaux 《Annals of Forest Science》2013,70(3):309-318
? Context
Over the past few decades, the impact of large herbivorous ungulates on forest vegetation has been clearly highlighted. Among those impacts, bark stripping of coniferous trees is one of the most damaging. Bark stripping leads to rot development, inducing serious loss of timber value.? Aims
The present study aimed firstly at evidencing the factors explaining the variations observed in fresh bark peeling rate for spruce and Douglas-fir in southern Belgium and secondly at identifying the key factors to consider when setting up a deer management plan.? Method
Fresh bark peeling rate was recorded with a systematic sampling survey from 2004 to 2007. The covered territory was then divided into 63 distinct hunting zones of area ranging from 1,000 to 25,000 ha. About 5,000 plots were monitored annually. Each zone was characterized with a large number of explanatory variables. The explanatory variables were integrated firstly into fixed linear models using a stepwise procedure, and then into a mixed model.? Results
The significant variables included in the model (R 2?=?44 %) are (by decreasing order of importance) red deer densities, proportion of coniferous stands and agricultural areas, snow cover, distance to urban habitats, and species diversity in the understory.? Conclusion
The models revealed the impacts of several factors on bark peeling: deer density, deer-carrying capacity of the territory, landscape structure, and severity of winter conditions. The adjusted model allowed subtracting the impact of winter conditions in order to produce a relevant indicator for hunting management. In addition, the model was used to assess the sensitivity of a forested area to bark peeling based on its environmental characteristics. 相似文献8.
? 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9.
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10.
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11.
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12.
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13.
? 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14.
Andrea Cutini Francesco Chianucci Roberta Chirichella Emanuela Donaggio Luca Mattioli Marco Apollonio 《Annals of Forest Science》2013,70(5):493-502
Context
Pulsed food resources may strongly affect the population dynamics of several consumer species, with consequences on the ecosystem. One of the most common pulsed resources is forest mast seeding.Aims
We analysed mast seeding in deciduous forests in a mountainous area of northern Apennines and its effect on population dynamics of wild boar (Sus scrofa L.).Methods
We performed a quantitative, 20-year analysis on annual seed production in Turkey oak (Quercus cerris L.), beech (Fagus sylvatica L.) and chestnut (Castanea sativa Mill.) forest stands using litter traps. The wild boar population density was estimated by means of drive censuses and hunting bag records. The role of other biotic (density of predators) and abiotic (climate) factors potentially affecting wild boar mortality was also investigated.Results
Turkey oak and chestnut showed high levels of seed production, whereas lower levels were found in beech. The pulsed resources of chestnut and Turkey oak positively affected piglet density. Analyses also highlighted the influence of snow cover and wolves on wild boar population dynamics.Conclusion
Wild boar can be considered a pulse rate species, the management of which can be improved by annual monitoring of seed production. 相似文献15.
16.
Hydraulic properties and embolism in small-diameter roots of five temperate broad-leaved tree species with contrasting drought tolerance 总被引:1,自引:0,他引:1
Paul K?cher Viviana Horna Ingo Beckmeyer Christoph Leuschner 《Annals of Forest Science》2012,69(6):693-703
? Context
It has been estimated that about half of a plant??s total hydraulic resistance is located belowground, but it is not well known how temperate tree species differ in root hydraulic properties and how these traits vary with the species?? drought tolerance.? Aims
We examined root anatomical and hydraulic traits in five broad-leaved tree species with different drought tolerance, analyzed the relation between root anatomy and hydraulic conductivity and root embolism, and investigated the relation of these traits to the species?? drought tolerance.? Methods
In small-diameter roots (2?C6?mm), we measured vessel diameters and vessel density, specific hydraulic conductivity, and the percental loss of conductivity (??native?? embolism) during summer in a mixed forest.? Results
Specific conductivity was positively related to vessel diameter but not to vessel density. Drought-tolerant Fraxinus showed the smallest mean vessel diameters and drought-sensitive Fagus the largest. Specific conductivity was highly variable among different similar-sized roots of the same species with a few roots apparently functioning as ??high-conductivity roots??.? Conclusion
The results show that coexisting tree species can differ largely in root hydraulic traits with more drought-sensitive trees apparently having larger mean vessel diameters in their roots than tolerant species. However, this difference was not related to the observed root conductivity losses due to embolism. 相似文献17.
? Context
There are many stand property–density relationships in ecology which represent emergent properties of plant populations. Examples include self-thinning, competition–density effect, constant final yield, and age-related decline in stand growth. We suggest that these relationships are different aspects of a general framework of stand property–density relationships.? Aims
We aim to illustrate the generalities and ecological implications of stand property–density relationships, and organize them in a comprehensive framework.? Methods
We illustrate relationships between stand property and density (1) at one point in time, (2) over time, and (3) independent of time. We review the consequences of considering different variables to characterize stand property (mean tree size, mean tree growth, stand growth, stand yield, stand leaf area).? Results
We provide a framework that integrates the broad categories of stand property–density relationships and individual expressions of these relationships. For example, we conclude that constant final yield is a special case of the growth–growing stock relationship for life forms were yield is a reasonable approximation of growth (non-woody plants).? Conclusion
There is support in the literature for leaf area being broadly integrative with respect to various expressions of stand property–density relationships. We show how this is and suggest implications for plant population ecology and forest management. 相似文献18.
Shrub biomass estimation in the semiarid Chaco forest: a contribution to the quantification of an underrated carbon stock 总被引:1,自引:0,他引:1
Georgina Conti Lucas Enrico Fernando Casanoves Sandra Díaz 《Annals of Forest Science》2013,70(5):515-524
Context
The quantification of biomass of woody plants is at the basis of calculations of forest biomass and carbon stocks. Although there are well-developed allometric models for trees, they do not apply well to shrubs, and shrub-specific allometric models are scarce. There is therefore a need for a standardized methodology to quantify biomass and carbon stocks in open forests and woodlands.Aims
To develop species-specific biomass estimation models for common shrubs, as well as a multispecies shrub model, for the subtropical semiarid Chaco forest of central Argentina.Methods
Eight shrub species (Acacia aroma, Acacia gilliesii, Aloysia gratissima, Capparis atamisquea, Celtis ehrenbergiana, Larrea divaricata, Mimozyganthus carinatus, and Moya spinosa) were selected, and, on average, 30 individuals per species were harvested. Their total individual dry biomass was related with morphometric variables using regression analysis.Results
Crown area as well as crown-shaped variables proved to be the variables with the best performance for both species-specific and multispecies shrub models. These allometric variables are thus recommended for standardized shrub biomass assessments.Conclusion
By accounting for the shrub component of the vegetation, our models provide a way to improve the quantification of biomass and carbon in semiarid open forest and woodlands. 相似文献19.
Laura Hernández Isabel Cañellas Iciar Alberdi Iván Torres Fernando Montes 《Annals of Forest Science》2014,71(2):161-171
? Context
It is assumed that global change is already affecting the composition, structure and distribution of forest ecosystems; however, detailed evidences of altitudinal and latitudinal shifts are still scarce.? Aims
To develop a method based on National Forest Inventory (NFI) to assess spatio-temporal changes in species distributions.? Methods
We develop an approach based on universal kriging to compare species distribution models from the different NFI cycles and regardless of the differences in the sampling schemes used. Furthermore, a confidence interval approach is used to assess significant changes in species distribution. The approach is applied to some of the southernmost populations of Pinus sylvestris and Fagus sylvatica in the Western Pyrenees over the last 40 years.? Results
An increase of the presence of the two species in the region was observed. Scots pine distribution has shifted about 1.5 km northwards over recent decades, whereas the European beech has extended its distribution southwards by about 2 km. Furthermore, the optimum altitude for both species has risen by about 200 m. As a result, the zone in which the two species coexist has been enlarged.? Conclusions
This approach provides a useful tool to compare NFI data from different sampling schemes, quantifying and testing significant shifts in tree species distribution over recent decades across geographical gradients. 相似文献20.
Jean-Daniel Bontemps Pierre Gelhaye Gérard Nepveu Jean-Christophe Hervé 《Annals of Forest Science》2013,70(4):329-343