A model of even-aged beech stands productivity with process-based interpretations

-The past history of a 300-year-old Quercus petraea stand (the "Futaie des Clos", 8 ha) located 20 km from the town of Le Mans in the Forest of Bercé in the western part of France (Sarthe) was analysed by a dendroecological approach. According to the number of healthy trees alive (> 400), the stand age (> 300 years), and the dimensions of the trees (dia: 92 cm; height: 45.2 m), this plot constitutes one of the most remarkable oak grove in France. High competition pressure between trees appeared to be the most important factor to explain the high-quality timber (high straight stems without wood defaults, narrow regular rings). After an initial 90-year period of decrease, this stand shows a 1 mm·year -1 growth increment from the 1810s to the present. The growth increase of 40-50% occurring for over than 20 years can be interpreted as a response to the increase of harvesting intensity. The influence of climate was evaluated by comparing earlywood, latewood and total ring indices with monthly climatic data collected at Le Mans over the period . Extreme growth years coincided with wet or dry springs (May-June) (± 40% of rainfall in relation to normal conditions) often associated with warm or fresh July. The climatic models accounted for between 18 and 26% of the variability of ring widths, and suggested that earlywood formation depended mainly on previous autumn hydric balance and winter temperature whereas the growth of the latewood band was maximum in early spring (positive effect of May hydric balance). The ecophysiological interpretations of the climatic correlations are discussed. dendroclimatology / tree ring / radial growth / climate / response function / Quercus petraea / long term chronology / pointer years Résumé -Dendroclimatologie du chêne sessile (Quercus petraea Mill.) en forêt de Bercé ("Futais des Clos", Sarthe, France). Une étude dendroécologique a été entreprise afin d'analyser l'évolution de la croissance radiale d'un peuplement âgé de chêne sessile (Quercus petraea Mill.) (la Futaie des Clos) localisé dans la forêt de Bercé à 20 km du Mans (Sarthe -France). En raison du nombre d'arbres présents (plus de 400 sur les 8 ha), de leur âge (> 300 ans en 2001) et de leur dimension (diamètre et hauteur moyens : 92 cm et 45,2 m), ce peuplement constitue une des plus remarquables chênaie sessiliflore de France. La sylviculture peu intensive pratiquée dans le peuplement explique en grande partie la très grande qualité des arbres (tronc très droit sans défaut, cernes fins réguliers). Après une période de décroissance de 90 ans, la largeur moyenne des cernes est d'environ 1 mm par an depuis 1810. L'augmentation de croissance observée depuis une vingtaine d'années peut être interprétée comme l'expression de l'augmentation de l'intensité des éclaircies (diminution de la compétition entre les arbres). L'effet du climat a été analysé en comparant les variations du bois initial, du bois final et du cerne complet aux données climatiques du Mans sur la période 1921-2001. Les années de croissance extrêmes (a...

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“…The value leads to zero when the competition pressure between trees is low. Values around 1 correspond to maximal competition pressure [15,16].…”

Section: Study Sitementioning

confidence: 99%

Climate-tree-growth relationships ofQuercus petraeaMill. stand in the Forest of Bercé (“Futaie des Clos”, Sarthe, France)

Lebourgeois¹,

2004

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“…Because empirical growth models are principally well suited for the investigation of a wide range of management alternatives, their coupling with productivity-environment models based on large-scale ecological gradients (Dhôte, 1996;Seynave et al, 2008) provides a cost-effective and accurate alternative approach for the prediction of timber production in the context of environmental change.…”

Section: Productivity-environment Relationships For Growth and Yield mentioning

confidence: 99%

“…It is a key input to most growth and yield simulators that are applied in forest management (Dhôte, 1996;García and Ruiz, 2003). Environmental change, however, challenges the assumption of constant site quality (Bontemps et al, 2009), which underlies the use of the site index concept, and thus the use of these traditional models.…”

Section: Productivity-environment Relationships For Growth and Yield mentioning

confidence: 99%

Models for supporting forest management in a changing environment

Fontes¹,

Bontemps²,

Bugmann³

et al. 2010

For. syst.

163

131

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Forests are experiencing an environment that changes much faster than during the past several hundred years. In addition, the abiotic factors determining forest dynamics vary depending on its location. Forest modeling thus faces the new challenge of supporting forest management in the context of environmental change. This review focuses on three types of models that are used in forest management: empirical (EM), process-based (PBM) and hybrid models. Recent approaches may lead to the applicability of empirical models under changing environmental conditions, such as (i) the dynamic state-space approach, or (ii) the development of productivity-environment relationships. Twenty-five process-based models in use in Europe were analyzed in terms of their structure, inputs and outputs having in mind a forest management perspective. Two paths for hybrid modeling were distinguished: (i) coupling of EMs and PBMs by developing signal-transfer environment-productivity functions; (ii) hybrid models with causal structure including both empirical and mechanistic components. Several gaps of knowledge were identified for the three types of models reviewed.The strengths and weaknesses of the three model types differ and all are likely to remain in use. There is a trade-off between how little data the models need for calibration and simulation purposes, and the variety of input-output relationships that they can quantify. PBMs are the most versatile, with a wide range of environmental conditions and output variables they can account for. However, PBMs require more data making them less applicable whenever data for calibration are scarce. EMs, on the other hand, are easier to run as they require much less prior information, but the aggregated representation of environmental effects makes them less reliable in the context of environmental changes. The different disadvantages of PBMs and EMs suggest that hybrid models may be a good compromise, but a more extensive testing of these models in practice is required.

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“…They are consistent with differential equations that are classically used in process-based models. These equations also have a process-based interpretation whereas the individual height and the stem profile equations are purely descriptive relations (Dhôte 1996).…”

Section: Discussionmentioning

confidence: 99%

Fagacées: a tree-centered growth and yield model for sessile oak (Quercus petraea L.) and common beech (Fagus sylvatica L.)

Moguédec¹,

Dhôte²

2011

Annals of Forest Science

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A model of even-aged beech stands productivity with process-based interpretations

Abstract: Summary — In order to describe the productivity of pure even-aged stands of common beech, a system of three differential equations is proposed for dominant height, basal area and total volume growth. The

Cited by 14 publications

References 17 publications

Climate-tree-growth relationships ofQuercus petraeaMill. stand in the Forest of Bercé (“Futaie des Clos”, Sarthe, France)

Climate-tree-growth relationships ofQuercus petraeaMill. stand in the Forest of Bercé (“Futaie des Clos”, Sarthe, France)

Models for supporting forest management in a changing environment

Fagacées: a tree-centered growth and yield model for sessile oak (Quercus petraea L.) and common beech (Fagus sylvatica L.)

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