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1.
? Context
Maritime pine (Pinus pinaster Aiton) is one of the most important Portuguese species, growing in pure stands ranging from even-aged to multi-aged structures. Current growth and yield models were developed only for even-aged, managed stands and/or for very specific regions of Portugal.? Aims
This paper focuses on the validation of the existing size-class model PBRAVO, adapted to even-aged stands, and on the subsequent development of a single tree distance-dependent growth and yield model (PBIRROL), both in distance-independent and distance-dependent versions, for uneven-aged stands.? Methods
The new model is composed of four modules, each with a set of sub-models for: tree variable prediction, tree volume prediction, future tree list prediction and growth projection.? Results
The evaluation of the PBRAVO and PBIRROL models showed that the new model gives more accurate predictions. Moreover, medium-term simulations provided consistent and logical predictions.? Conclusion
It was verified that individual tree models are more suited to simulate poorly managed uneven-aged stands than diameter distribution models. No clear superiority of distance-dependent models was found over models using just distance-independent measures of inter-tree competition. 相似文献2.
Northern hardwood stands, notably those with American beech (Fagus grandifolia Ehrh), sugar maple (Acer saccharum Marsh.), and yellow birch (Betula alleghaniensis Britton), are abundant across the forested landscapes of northeastern USA and southeastern Canada. Recent studies have reported an increasing dominance of American beech in the understory and midstory of these forests. Beech is a commercially less desirable tree species due to its association with beech-bark disease, and because it commonly interferes with the regeneration of other more desirable tree species. We examined hardwood regeneration characteristics nine years after application of a 3 × 4 factorial combination of glyphosate herbicide (0.56, 1.12, and 1.68 kg ha?1) and surfactant concentrations (0.0, 0.25, 0.5, and 1.0% v v?1) to release sugar maple regeneration from beech-dominated understories using three stands that received shelterwood seed cutting in central Maine. Measurements nine years after treatment showed that glyphosate rate increased both absolute (AD) and relative density (RD) of sugar maple regeneration, but not its height (HT). In contrast, beech AD, RD, and HT were all significantly reduced with increasing glyphosate rate. Post-release browsing by ungulates and a high residual overstory basal area resulted in reduced sugar maple HT. Our results indicated that glyphosate herbicide applied in stands that have been recently shelterwood seed cut can significantly increase the abundance of sugar maple regeneration. However, subsequent browsing damage combined with the negative influence of the residual overstory cover can limit the longer-term benefit of understory herbicide treatments. Subsequent removal of the overstory and browsing-control measures may be needed to promote sugar maple regeneration over beech in similar northern hardwood stands. 相似文献
3.
Annabelle Amm Christian Pichot Philippe Dreyfus Hendrik Davi Bruno Fady 《Annals of Forest Science》2012,69(7):845-856
? Context
Dispersal and recruitment play a critical role in determining the abundance and the spatial structure of regeneration.? Aim
In this study, we estimated landscape scale seed dispersal using the inverse modeling method by fitting seedling counts to seed tree location and fertility in the European silver fir Abies alba Miller.? Methods
Seed trees and seedlings from three age cohorts were counted in 30 plots on Mont Ventoux (southeastern France) at elevations from 995 to 1,605?m, where the following ecological variables were measured: elevation, slope, aspect, light availability, and tree density. We developed and fitted a dispersal model, including a new parameter, recruitment rate, which depended both on the ecological characteristics of the plots and on seed production.? Results
Elevation was the factor that affected seedling recruitment the most, with an optimum value at around 1,200?m. Estimated A. alba seed dispersal distances were short (median values for the three cohorts, respectively, 16.4?C13.2?C19.6?m).? Discussion
We demonstrated that including the ecological characteristics of plots and post-dispersal recruitment processes realistically reduced estimates of seed dispersal distances which are otherwise grossly over-estimated using inverse modeling procedures. 相似文献4.
Giulia Attocchi 《Annals of Forest Science》2013,70(7):663-673
Context
Avoidance or control of epicormic shoots is among the major silvicultural challenges for the production of high-quality oak timber. In northern Europe, contemporary oak silviculture aims to produce valuable timber on a relatively short rotation, applying early, heavy thinning combined with artificial pruning.Aims
The aim of this study was to analyse the effects of pruning and stand density on the production of new epicormic shoots on young trees of pedunculate oak (Quercus robur L.).Methods
The study was based on two field experiments in even-aged stands of pedunculate oak subjected to different thinning practices and early selection of potential future crop trees. From ages 13 to 15 years, stem density was reduced to 300 trees ha?1, 1,000 ha?1 or stands remained unthinned. Pruning was conducted on selected trees at ages 22–24 years. At that age, the stem density in unthinned control plots ranged from 2,500 to 3,100 ha?1. All treatments were replicated twice within each experiment.Results
Pruning led to an overall increase in the total production of new epicormic shoots. More epicormic shoots were produced in the lower part of the stem (0–3 m in height) than in the upper part (3–6 m). The number of new epicormic shoots increased with increasing stand density.Conclusion
Early, heavy thinning combined with high pruning at regular intervals may help shorten the rotation length for pedunculate oak without further reduction in wood quality than that which is caused by wider annual growth rings. 相似文献5.
6.
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7.
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8.
Maaike De Ridder Wannes Hubau Jan Van Den Bulcke Joris Van Acker Hans Beeckman 《Annals of Forest Science》2010,67(5):501-501
9.
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10.
Igor Drobyshev Mats Niklasson Hans Linderson Kerstin Sonesson Matts Karlsson Sven G. Nilsson Jan Lanner 《Annals of Forest Science》2008,65(4):401-401
11.
Rafał Ważny 《Annals of Forest Science》2014,71(7):801-810
Context
The requirement for rebuilding forecrop stands besides replacement of meadow vegetation with forest plants and formation of soil humus is the presence of a compatible ectomycorrhizal (ECM) fungal community.Aims
This study aims to assess ectomycorrhizal fungi diversity associated with silver fir (Abies alba Mill.) seedlings regenerating in silver fir stands and Scots pine forecrops.Methods
One-year-old seedlings were sampled in six study sites: three mature fir forests and three pine forests. ECM fungi were identified by polymerase chain reaction amplification and sequencing of the internal transcribed spacer of rDNA.Results
The mean mycorrhizal colonization exceeded 90 %. Thirty-six ectomycorrhizal taxa were identified in fir stands and 23 in pine forecrops; ten out of these species were common to both stands. The fungal communities were different between study sites (R?=?0.1721, p?=?0.0001). Tomentella stuposa was the only species present at all sites.Conclusion
Silver fir seedlings in Scots pine forecrops supported smaller ECM fungal communities than communities identified in mature silver fir stands. Nevertheless, fungal colonization of seedling roots was similar in both cases. This suggests that pine stands afforested on formerly arable land bear enough ECM species to allow survival and growth of silver fir seedlings. 相似文献12.
Jean-Daniel Bontemps Pierre Gelhaye Gérard Nepveu Jean-Christophe Hervé 《Annals of Forest Science》2013,70(4):329-343
? Context
While historical increases in forest growth have been largely documented, investigations on historical wood density changes remain anecdotic. They suggest possible density decreases in softwoods and ring-porous hardwoods, but are lacking for diffuse-porous hardwoods.? Aims
To evaluate the historical change in mean ring density of common beech, in a regional context where a ring-porous hardwood and a softwood have been studied, and assess the additional effect of past historical increases in radial growth (+50 % over 100 years), resulting from the existence of a positive ring size–density relationship in broadleaved species.? Methods
Seventy-four trees in 28 stands were sampled in Northeastern France to accurately separate developmental stage and historical signals in ring attributes. First, the historical change in mean ring density at 1.30 m (X-ray microdensitometry) was estimated statistically, at constant developmental stage and ring width. The effect of past growth increases was then added to assess the net historical change in wood density.? Results
A progressive centennial decrease in mean ring density of ?55 kg?m?3 (?7.5 %) was identified (?10 % following the most recent decline). The centennial growth increase induced a maximum +25 kg?m?3 increase in mean ring density, whose net variation thus remained negative (?30 kg?m?3).? Conclusions
This finding of a moderate but significant decrease in wood density that exceeds the effect of the positive growth change extends earlier reports obtained on other wood patterns in a same regional context and elsewhere. Despite their origin not being understood, such decreases hence form an issue for forest carbon accounting. 相似文献13.
Sergio de-Miguel Timo Pukkala Nabil Assaf José Antonio Bonet 《Annals of Forest Science》2012,69(4):455-465
Context
The past management of Pinus brutia forests in Lebanon has led to diverse stand structures that cannot be easily classified as even-aged (EA) or uneven-aged (UA). Most stands are between these stand types, and they may be called as ??semi-even-aged??. This is a very common characteristic throughout the Mediterranean conifer forests and makes the choice between the EA and UA approaches problematic, in both management and modelling. However, previous research has devoted little attention to the performance of growth and yield models when applied to transitional stand structures.Aims
The aim of this study was to find the best modelling approach and to recommend equations for simulating the dynamics of the semi-even-aged P. brutia stands of Lebanon on an individual-tree basis.Methods
Fifty sample plots were measured in Lebanon. Individual-tree growth models were fitted to the whole dataset using either UA or EA modelling approach. Models were also fitted using two sub-samples containing the most EA and the most UA plots. The performance and accuracy of the two modelling approaches were evaluated in all three datasets.Results
The article provides the first complete growth model for uneven-aged P. brutia stands. The EA sub-models presented better statistical fitting. However, the UA sub-models enabled more accurate predictions of wood production and were almost as good as the EA sub-models when predicting stand dynamics of the EA plots. The EA approach provided poor predictions, and the errors were high when it was applied to UA stands.Conclusions
In structurally complex stands, the UA modelling approach is to be preferred since it predicts the whole stand dynamics more accurately and enables simulations of a broader range of silvicultural treatments. 相似文献14.
Patterns of litterfall and nutrient return at different altitudes in evergreen hardwood forests of Central Taiwan 总被引:1,自引:0,他引:1
Background
This study was designed to evaluate the internal nutrient cycling of litterfall in different elevation subtropical forests of Central Taiwan.Methods
The litterfall of evergreen hardwoods at three elevations, specifically Mt. Peitungyen (2,078?m), Hui-Sun experimental forest (HSEF) (1,066?m), and Lienhauchi (782?m) in central Taiwan, was collected monthly using traps and sorted into leaves, twigs, reproductive litter, and miscellaneous material. In addition, the litter on the forest floor was collected trimonthly. All the samples were weighed and measured for C, N, P, K, Ca, and Mg concentrations and fluxes from March 2009 to February 2010.Results
The annual litterfall productions were 6.58, 8.24, and 9.17?Mg?ha?1?year?1 at Mt. Peitungyen, HSEF, and Lienhauchi, respectively. At more than 60?%, leaves were the main component of the total litterfall. There was smallest decomposition constant (0.487) at Mt. Peitungyen. The nutrient fluxes increased as elevation decreased. The litterfall correlated positively with rainfall at Lienhauchi, with temperature at HSEF, and with temperature and rainfall at Mt. Peitungyen.Conclusion
The annual litterfall decreased with an increase in elevation. The turnover rate was faster at HSEF than at Mt. Peitungyen. Thus, the forest managers should pay more attention to understand and monitor plant community responses to global warming and nutrient loss. 相似文献15.
Productivity of temperate broad-leaved forest stands differing in tree species diversity 总被引:1,自引:0,他引:1
16.
Modelling site quality and individual-tree growth in pure and mixed Pinus brutia stands in north-east Greece 总被引:1,自引:0,他引:1
Marc Palahí Timo Pukkala Dimitrios Kasimiadis Konstantinos Poirazidis Aristotelis C. Papageorgiou 《Annals of Forest Science》2008,65(5):501-501
17.
D. Hessenmöller O. Bouriaud D. Fritzlar A.S. Elsenhans 《Scandinavian Journal of Forest Research》2018,33(7):668-680
Maintaining a permanent forest canopy cover and eventually harvesting wood in a final harvest according to predefined dimensions is often considered as prototype for future management of deciduous forests. An uneven-aged structure is considered by the public to resemble “natural” conditions, and by forest engineers it is considered as being more resilient to disturbances. In the Hainich-Dün region of Thuringia, Germany, beech-dominated selection forests covering about 10,000?ha have been managed for almost 1000 years, initially by irregular use, but as regular selection system since about 200 years. Managing these stands remains difficult, due to the lack of yield tables and a quantification of harvest of uneven-aged stands considering differences in site conditions and handling of over-sized trees. It is the objective of the present study to develop tables of target stand volumes, increments, and harvest for different diameter ranges of uneven-aged stands according to site conditions. The present study is based on repeated grid-based inventories of about 2150 plots, which were partly re-inventoried 3 times over the past 20 years. The recommended target wood volumes vary between 296 and 388 m3 ha?1. Stand growth rates of different yield classes were estimated to range between 6.7 and 7.7 m3 ha?1 yr?1 which is 30% lower than for age class forest. Nevertheless, the economic returns are higher. Thus, selective cutting with single tree selection remains a viable silvicultural system, but it may change over time into small-scale shelter-woods for improving growth of regeneration. 相似文献
18.
Context
Fine scale regeneration patterns of coexistent species are influenced by regeneration mechanisms and microsite requirements. Spatial patterns may be either disjunct or overlapping, which will determine competitive effects and microsite dominance, and future forest composition.Aims
Using American beech (Fagus grandifolia Ehrh.) and sugar maple (Acer saccharum Marshall) as an example, three hypotheses were tested: (1) random beech spatial patterns, (2) clumped spatial patterns of small sugar maple seedlings, and (3) disjunct beech and sugar maple patterns.Methods
Individual stems were sampled in a contiguous grid of 1-m2 quadrats across a 576-m2 area at three sites. Densities were separated into three height classes (≤30 cm, 30–90 cm, and?>?90 cm, ≤4 cm diameter at breast height). Spatial statistics and regression were used to analyze spatial patterns and correlations.Results
Beech and seedling sugar maple patterns were patchy, rejecting the first and not rejecting the second hypotheses. Hypothesis three was rejected because patches of the two species overlapped with advance regeneration beech overtopping sugar maple.Conclusion
Patchy patterns of advance regeneration beech and post-harvest sugar maple establishment suggest spatiotemporal niche partitioning. Beech had a competitive height advantage following harvest, but sugar maple still occurred in beech-free patches and beneath overtopping beech at a fine scale. Self-replacing beech patterns will ensure the species will continue dominance unless a selective chemical or manual treatment is applied that removes beech and releases sugar maple. 相似文献19.
20.