Interactions between forest stands and microclimate: Ecophysiological aspects and consequences for silviculture

Abstract

-At a local scale, forest trees and stands have a marked influence on climate; thus it is possible to define microclimates. These effects depend on local climatic characteristics and stand type. All climatic parameters should be considered, but particular attention should be paid to temperature, light and water. From a silvicultural point of view knowledge of the interactions existing between microclimatic conditions and stands, in conjunction with information now available concerning tree ecophysiology make it possible to produce viable applications which are useful for silviculture during stand formation, and for applying silvicultural treatments. Whitout a doubt, taking forest cover interactions into account (climate and ecophysiological potential of species) is the basis of sustainable management in forests. Based on the current knowledge about young stands, it is possible to use existing vegetation cover, in a more or less modified form, to improve temperature conditions especially in relation to spring frost damage, and to improve water conditions for both plant uptake and plant growth for a variable period depending on the species, but for a minimum of 4 to 5 years. For clearing and thinning, the effects of microclimatic changes created by this type of forestry management, and consequently the response of trees in terms of photosynthesis and growth, are now well defined.forest stands / microclimate / ecophysiology / silviculture Résumé -Interactions entre peuplements forestiers et microclimat : aspect écophysiologique et conséquences pour la sylviculture. Les arbres et les peuplements forestiers exercent, au niveau local, des influences notables sur le climat ; on peut alors définir des microclimats. Ces influences sont dépendantes des caractéristiques du climat local et des types de peuplement. L'ensemble des paramètres climatiques sont à considérer, mais une attention particulière doit être portée à la température, à la lumière et à l'eau. Au plan sylvicole la connaissance des interactions existant entre conditions microclimatiques et peuplements, couplées aux informations maintenant disponibles concernant l'écophysiologie des arbres permettent de déboucher sur des applications fiables, utilisables par la sylviculture pour la création des peuplements et la mise en oeuvre des traitements sylvicoles. Incontestablement la prise en compte des interactions couvert forestier -climat et potentialités écophysiologiques des essences est à la base d'une gestion durable des forêts. Sur la base des connaissances actuelles et pour ce qui concerne les jeunes peuplements, il est possible d'utiliser le couvert végétal préexistant, plus ou moins modifié, pour améliorer les conditions thermiques notamment au plan des risques de dégâts de gel au printemps et pour améliorer les conditions hydriques tant pour ce qui concerne la reprise que la croissance des plants pendant une période variable selon les espèces, mais d'une durée minimale de 4 à 5 ans. Pour les dégagements et éclaircies l'effet des modifications micr...

The effects of thinning intensity and tree size on the growth response to annual climate in Cedrus atlantica: a linear mixed modeling approach

“…This difference increased with increasing site xericity. The buffer effect on environmental conditions provided by dominant tree canopy (Aussenac 2000) could be more important at water-limited sites, thereby explaining that the suppressed trees at our study site are less sensitive to the inter-annual water balance variability. In another view, the lower growth sensitivity of suppressed trees is due to a loss of plastic capacity in those trees strongly constrained by competition (Linares et al 2010).…”

Influence of light and competition on crown and shoot morphological parameters of Norway spruce and silver fir saplings

“…Firs in general are considered to have a higher ability to maintain a positive carbon balance at low light intensities than spruces [1,18,21,32]. This difference has been primarily attributed to a higher morphological plasticity in relation to light [21].…”

“…Therefore, understanding how these traits vary in relation to interacting factors is important in order to promote and assure effectively natural regeneration [1]. Several studies have shown that the effect of light on crown, shoot and needle morphology differs among tree species, with shade-tolerant species typically showing greater morphological changes along a light gradient than do the more shade-intolerant species [4,7,8,12,33].…”

Untitled

“…Consideraram-se duas categorias distintas para a cobertura florestal nativa e outra para a floresta exótica por terem diferentes características de cobertura do solo ocasionando diferentes taxas de escoamento superficial. Na categoria floresta exótica, considerando-se somente a cobertura do solo, o escoamento é superior à floresta nativa, pois as práticas da silvicultura local utilizam uma maior densidade de árvores que diminuem a luminosidade no sub-bosque, principalmente no primeiro decênio de cultivo (Aussenac, 2000). O maior sombreamento ocasiona uma diminuição na cobertura do solo por plantas, principalmente das espécies de gramíneas que possuem a fotossíntese com o ciclo do ácido dicarboxílico C4, e estas requerem uma maior energia luminosa e temperatura para seu pleno desenvolvimento (Odum, 1988).…”