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1.
Jorge Olivar Stella Bogino Cyrille Rathgeber Vivien Bonnesoeur Felipe Bravo 《Annals of Forest Science》2014,71(3):395-404
? Context
Modification of stand density by thinning may buffer the response of tree growth and vigor to changes in climate by enhancing soil water availability.? Aims
We tested the impact of thinning intensity on cambial growth of Aleppo pine (Pinus halepensis L.) under semi-arid, Mediterranean conditions.? Methods
A multiple thinning experiment was established on an Aleppo pine plantation in Spain. We analysed the stem growth dynamics of two different crown classes under four different thinning intensities (15 %, 30 %, and 45 % removal of the basal area) for 2 years, based on biweekly band dendrometer recordings. Local relative extractable soil water was derived from the use of a water balance model Biljou© (available at https://appgeodb.nancy.inra.fr/biljou/) and used as an explanatory variable.? Results
Radial growth was mainly controlled by soil water availability during the growing season, and differed by crown class. The growth rates of dominant trees were significantly higher than the growth rates of suppressed trees. Removal of 30 % and 45 % of the initial basal area produced a growth release in both dominant and suppressed trees that did not occur under less intense thinning treatments.? Conclusions
Soil water availability was the main driver of radial growth during the growing season. Forest management confirmed its value for ameliorating the effects of water limitations on individual tree growth. These results may help managers understand how altering stand density will differentially affect diameter growth responses of Aleppo pine to short-term climatic fluctuations, promoting forests that are resilient to future climatic conditions. 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.
4.
Using density management diagrams to assess crown fire potential in Pinus pinaster Ait. stands 总被引:1,自引:0,他引:1
Ibán Gómez-Vázquez Paulo M. Fernandes Manuel Arias-Rodil Marcos Barrio-Anta Fernando Castedo-Dorado 《Annals of Forest Science》2014,71(4):473-484
Context
Density management diagrams (DMDs) are useful for designing, displaying and evaluating alternative density management regimes for a given stand-level management objective. The inclusion of variables related to crown fire potential within DMDs has not previously been considered.Aims
The aim of this study was to include isolines of variables related to crown fire initiation and spread in DMDs to enable identification of stand structures associated with different types of wildfire.Methods
Biometric and fuel data from maritime pine (Pinus pinaster Ait.) stands in NW Spain were used to construct DMDs. Different surface and crown fire behaviour models were used together to estimate crown fire potential.Results
The crown fire potential varied greatly throughout development of the maritime pine stands. Low stands were more prone to crowning. The type of crown fire was mainly determined by stand density.Conclusion
The DMDs developed can be used to identify relationships between stand structure and crown fire potential, thus enabling the design of thinning schedules aimed at reducing the likelihood of crowning. 相似文献5.
Marie Nourtier André Chanzy Maxime Cailleret Xie Yingge Roland Huc Hendrik Davi 《Annals of Forest Science》2014,71(6):683-695
Context
Silver fir is declining and dying at its southern margin on the Mediterranean area, where climate is expected to be warmer and drier. At a regional scale, silver fir seems to be vulnerable to drought, and at a forest stand scale, tree death seems to be distributed according to soil water availability.Aim
To understand the vulnerability of silver fir to drought, factors involved in the regulation of transpiration were assessed with respect to soil properties in order to document the spatial distribution of death rates.Methods
Soil properties were characterized by electric resistivity measurements. Sap flow density and predawn needle water potential were recorded on sampled trees during several years, and crown specific transpiration was estimated. In addition, the vulnerability of coarse roots and branches to cavitation was quantified.Results and conclusion
Trees growing on soils with a large water storage capacity were the most vulnerable to drought induced soil water deficits. Transpiration was down-regulated as soon as predawn water potential decreased. The vulnerability to cavitation was low, which protected the trees from run-away xylem embolism. Severe soil water deficits led to a rapid decrease of transpiration, which was still visible the following year. The drop-off in transpiration was mainly due to inner sap flow that almost ceased after the drought on all monitored trees. Our results suggest that root dynamic and the ability of roots to take up water were modified by soil water deficit over several years. Such a regulation scheme needs to be better documented and included in models to address silver fir forest responses to drought. 相似文献6.
Anne-Sophie Sergent Nathalie Bréda Léopoldo Sanchez Jean-Charles Bastein Philippe Rozenberg 《Annals of Forest Science》2014,71(6):709-720
Context
Since the 2003 drought and heat wave, Douglas-fir dieback has been reported in France in trees older than 30 years. Consequently, it is questioned whether selected Douglas-fir provenances are suited to the frequent and severe drought events which are forecast due to climate change.Aims
Our objective was to contribute to the screening of variability in productivity and growth response to soil-water deficit of mature trees from provenances not currently used for plantation in France.Methods
We sampled 22 provenances, including coastal and interior Douglas-fir, covering a wide part of its natural distribution, from Oregon to California for coastal provenances and from British Columbia to New Mexico for interior provenances. These provenances were planted at the mid 1970s in two provenance trials located in the south-west area of France. Variability of productivity, of wood density, and of radial growth in response to drought episodes among provenances was quantified and related to soil-water deficit computed by daily water balance calculations.Results
Whatever the provenance, annual radial growth is highly dependent on local soil-water deficit (Felines R 2 = 0.57, Le Treps R2 = 0.49). Radial growth and wood properties exhibit large differences between provenances at 30 years old. Variability between provenances for all wood characteristics studied is mainly structured geographically. Coastal provenances perform best for productivity at 30 years old (619 cm2?±?59), and exhibit a small growth reduction in 2004, the second successive year of drought (?10.7 %?±?3.8). Surprisingly, the southern interior provenances from the driest environments in the natural range show a large growth reduction in 2004 (?30.5 %?±?5.2).Conclusions
The provenances tested exhibited significant differences in growth performance and growth reduction induced by the soil-water deficit. The approach coupling retrospective analysis of radial growth on mature trees and water balance modelling is relevant for evaluating provenance adaptation to more frequent or severe drought episodes. 相似文献7.
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8.
9.
Models of the longitudinal distribution of ring area as a function of tree and stand attributes for four major Canadian conifers 总被引:1,自引:0,他引:1
Context
It is widely accepted that ring area increment generally increases from the tree apex to the crown base and is more-or-less constant below the crown base (Pressler’s law), but few quantitative models of this distribution have been developed.Aims
The aim of this study was to develop a model of ring area increment using easily obtained crown features and other tree or stand characteristics in order to further the understanding and prediction of tree growth, form, and wood quality.Methods
The models were fit to stem analysis observations from white spruce, black spruce, balsam fir, and lodgepole pine.Results
In the final model, which includes tree crown and stand variables, ring area increment within the crown region was slightly curvilinear, the slope of ring area increment below the crown was non-zero, and the effect of butt swell was appreciable up-to a relative height of 0.10.Conclusions
The high accuracy of the mixed effects model suggests that the three-component model form is appropriate for describing ring area profiles, whereas some tree-to-tree variation remains unexplained. The tree and stand variables used in these models can be easily measured in the field or obtained from remote sensing techniques. 相似文献10.
Paul Köcher Tobias Gebauer Viviana Horna Christoph Leuschner 《Annals of Forest Science》2009,66(1):101-101
11.
Alberto Vázquez de Castro Juan A. Oliet Jaime Puértolas Douglass F. Jacobs 《Annals of Forest Science》2014,71(1):91-99
Context
Tube shelters have been shown to enhance field performance of several Mediterranean species, but responses of newly planted seedlings to the microenvironment induced by shelter walls with different light transmissivity are still poorly documented.Aims
We studied effects of a range of shelters with varying light transmissivity on post-planting seedling responses during the wet season establishment phase for two Mediterranean trees of contrasting functional ecology.Methods
Root growth, biomass allocation, water potential, and chlorophyll fluorescence of Quercus ilex and Pinus halepensis seedlings were evaluated across shelters varying in light transmissivity (80, 40, 20, and 10 % plus a mesh shelter) with irrigation.Results
Plants in dark tubes (20 and 10 % light transmissivity) had less above- and belowground growth and more than two times greater leaf to protruding roots mass ratio, with shoot growth response of Q. ilex being less plastic. Ratio of leaf area/protruding roots area decreased when light transmissivity increased, although no differences were found at ≥40 % transmissivity. Xylem water potential indicated lack of water stress, and high maximum photosynthetic efficiency (F v/F m) values show no photoinhibition symptoms irrespective of light transmissivity.Conclusion
Shelter transmissivity ≥40 % promotes rapid and vigorous root growth immediately after planting for these species. This minimum transmissivity should be considered as a target when designing shelters to help root development and improve water balance of Mediterranean seedlings. 相似文献12.
? 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13.
? Context
Soil temperature can limit tree growth and function, but it is often unaddressed in understanding the successional status of trees.? Aims
We tested how soil temperature affected carbon allocation strategies of two dominant co-occurring boreal conifer species, Pinus contorta and Picea mariana.? Methods
We measured nonstructural carbon (NSC) concentrations, biomass, and photosynthesis of dormant and actively growing 2-year-old seedlings in response to three soil temperatures (5, 10, and 20 °C) under a common ambient air temperature.? Results
For both species, variation in carbon reserves with soil temperature was more pronounced following seedling growth than during dormancy. For both species and all organ types (roots, needles, and stems), NSC concentrations were highest when seedlings were grown at 5 than 20 °C. Mass adjusted for NSC content was negatively correlated with NSC concentration for all organ types of both species. Soil temperature had a marginally significant effect on photosynthesis of pine; seedlings grown at 10 or 20 °C acquired more carbon than seedlings grown at 5 °C. Spruce seedlings photosynthesized more when grown at 20 °C than at 5 or 10 °C.? Conclusion
Interspecific differences in allocation of carbon may underlie the responses of P. mariana and P. contorta to cold soils and consequently their successional status. 相似文献14.
J. Julio Camarero Rubén D. Manzanedo Raúl Sanchez-Salguero Rafael M. Navarro-Cerrillo 《Annals of Forest Science》2013,70(8):769-780
Context
Tree populations at the rear edge of species distribution are sensitive to climate stress and drought. However, growth responses of these tree populations to those stressors may vary along climatic gradients.Aims
To analyze growth responses to climate and drought using dendrochronology in rear-edge Pinus nigra populations located along an aridity gradient.Methods
Tree-ring width chronologies were built for the twentieth century and related to monthly climatic variables, a drought index (Standardized Precipitation–Evapotranspiration Index), and two atmospheric circulation patterns (North Atlantic and Western Mediterranean Oscillations).Results
Growth was enhanced by wet and cold previous autumns and warm late winters before tree-ring formation. The influence of the previous year conditions on growth increased during the past century. Growth was significantly related to North Atlantic and Western Mediterranean Oscillations in two out of five sites. The strongest responses of growth to the drought index were observed in the most xeric sites.Conclusion
Dry conditions before tree-ring formation constrain growth in rear-edge P. nigra populations. The comparisons of climate-growth responses along aridity gradients allow characterizing the sensitivity of relict stands to climate warming. 相似文献15.
Marc Soler Martin José Antonio Bonet Juan Martínez De Aragón Jordi Voltas Lluís Coll Víctor Resco De Dios 《Annals of Forest Science》2017,74(3):51
Key message
No temporal change was recorded during summer in fuel availability in Pinus pinaster stands, contrary to predictions from the Forest Fire Weather Index. Also, thinning had no mid-term effect on fuel moisture or canopy structure.Context
Forest fires are a major problem in Mediterranean countries. Management actions, such as fuel reductions, are one of the main tools to diminish fire risk, but the midterm efficacy of such tools remains largely untested with empirical data.Aims
Here, we test for midterm effects of thinning on fuel moisture and crown bulk density in P. pinaster stands and whether temporal variations in fuel moisture correlated with predictions from the Fire Weather Index, a commonly used index on fire risk, and its components.Methods
We compared fuel moisture over a fire season and crown bulk density in nine pairs of thinned/unthinned plots 7 years after treatments were applied.Results
We observed that fuel moisture remained stable during a fire season, as a likely result of drought-induced physiological adjustments, including stomatal regulation and others, which allow leaves to maintain a large humidity even during drought, and that thinning had no midterm effect on fuel moisture or crown bulk density. Moreover, the Fire Weather Index and its components displayed different temporal dynamics than those observed in fuel moisture.Conclusion
These results are important as they indicate that thinning may only have a limited, short-term impact towards diminishing the potential for crown fire spread in these stands and that current indices to evaluate fire risk may require a re-evaluation.16.
Context
Warmer temperatures and anthropogenic N depositions are altering soil nutrient cycles and plant nutrition worldwide and are projected to rise dramatically in the future, particularly at the high latitudes. How much will such alterations affect symbiotic organisms such as ectomycorrhizae (ECM)?Aims
The aim was to investigate the short-term effects of warmer soil temperatures and N-enriched precipitations on roots and ECM.Methods
A field experiment was established during 2008–2010 in two black spruce (Picea mariana) stands of the boreal forest of Quebec, Canada. The ECM of 12 trees per site were counted and identified by morphotyping.Results
After 3 years, soil heating markedly modified the proportions of vital root tips and ECM in the colder stand, while no effect of the N-enriched rain was observed on soil chemistry and consequently on roots and ECM. Density and ramification of root tips were not affected by the treatments.Conclusion
The hypothesis that the treatments would alter the ECM was confirmed only partially in the colder stand. The type of application and amount of N supplied were unable to substantially modify in the short-term growth conditions of roots and ECM, explaining the observed results. 相似文献17.
Ervin Rasztovits Imre Berki Csaba Mátyás Kornél Czimber Elisabeth Pötzelsberger Norbert Móricz 《Annals of Forest Science》2014,71(2):201-210
Context
Projections of species distribution models under future climate are usually based on long-term averages. However, singular extreme drought events presumably contribute to the shaping of distribution limits at the retreating low-elevation xeric limits.Methods
The objectives of this study were to set up a distribution model based on extreme drought events (EDM), which uses sanitary logging information as a proxy of vitality response of beech, and compare it with the results of classical species distribution models (SDMs).Results
Predictions of the EDM for 2025 were in agreement with those of the SDM, but EDM predicted a more serious decline in all regions of Hungary towards the end of the century.Conclusion
These results suggest that the predicted increase in frequency and severity of drought events may further limit the distribution of beech in the future. 相似文献18.
Context
Although adventitious shoots are produced in many tree species in response to injury, little is known about the effects of salinity on sprouting.Aims
The main objective was to examine the sprouting capacity of Pinus leiophylla seedlings in relation to injury and physiological changes induced by NaCl.Methods
Seedlings were grown in controlled-environment growth rooms and treated with 0, 100, 150, and 200 mM NaCl. Numbers of adventitious shoots were recorded and growth and physiological parameters measured after 64 days of treatments and following a 30-day recovery period.Results
NaCl treatments triggered sprouting of adventitious shoots, mainly in the lower parts of the stems. However, fewer sprouts were induced by 200 mM NaCl compared with the lower concentration treatments. These changes were accompanied by needle necrosis, decreased chlorophyll concentrations, seedling dry mass, and stem diameter. Stomatal conductance, net photosynthesis, and root hydraulic conductance decreased with increasing NaCl concentrations and did not return to the control levels after 30 days of stress relief.Conclusions
Pinus leiophylla has the regeneration potential when exposed to salinity. However, very high salt concentrations induce severe physiological impairments and, consequently, a decrease of this regeneration potential. 相似文献19.
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20.
Responses of labile soil organic carbon and enzyme activity in mineral soils to forest conversion in the subtropics 总被引:1,自引:0,他引:1