The dependency of the size-growth relationship of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica [L.]) in forest stands on long-term site conditions, drought events, and ozone stress

Trees (Impact Factor: 1.65). 06/2010; 25(3):355-369. DOI: 10.1007/s00468-010-0510-1


Against a backdrop of increasing climate change, the effects of site conditions, drought events and ozone stress on the size-growth
relationship in Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica [L.]) stands are analyzed. The size-growth relationship is represented by a straight line defined by intercept and slope
of a simple linear equation with stem diameter at height 1.30m as independent variable and annual stem diameter increment
at height 1.30 as dependent variable. On the basis of 64 long-term experimental plots dating back to 1871 and representing
an ecological gradient from fertile to poor sites, it is shown that poorer sites exhibit shallower slopes of the linear size-growth
relationships than fertile sites. Annual measurements of the size-growth relationship, including the extremely dry years of
1976 and 2003, also showed that lower stand growth rates result in shallower size-growth relationship slopes. By comparing
stands with and without experimental twice-ambient ozone exposure between 2000 and 2007, it was found that ozone stress can
significantly reduce the slope of the size-growth relationship. This indicates that limiting site condition, whether acute
or chronic in nature, distinctly reduces the superiority of tall trees, and that a lower degree of resource limitation increases
the steepness of the size-growth relationship. The causes for this behavior and the consequences for stand dynamics, silvicultural
treatment and prognostication by models are discussed.

KeywordsSize-asymmetric growth–Diameter increment–Competition–Resource partitioning–Limitation–Allocation principle–Stand structure

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Available from: Jochen Dieler, Apr 03, 2015
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    • "Typically, site and tree selection are intended to enhance the climate signal (Cook and Kairiukstis, 1990; Schweingruber, 1996). However, trees show divergent climate–growth associations from their neighbours within a stand, because growth responsiveness to climate depends on site and tree characteristics like forest composition (Pretzsch and Dieler, 2011), tree-to-tree competition intensity (Linares et al., 2010) or tree age and size (Carrer and Urbinati, 2004; Martín-Benito et al., 2008; Szeicz and MacDonald, 1994). "
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    ABSTRACT: Stands and trees may exhibit different climate–growth responses compared to neighbouring forests and individuals. The study of these differences is crucial to understanding the effects of climate change on the growth and vulnerability of forests and trees. In this research we analyse the growth responsiveness of primary Norway spruce forests to climate as a function of different stand (elevation, aspect, slope, crowding, historic disturbance regime) and tree (age, tree-to-tree competition) features in the Romanian Carpathians. Climate–growth relationships were analysed using Pearson correlation coefficients between ring-width indices (RWIs) and climate variables. The influence of stand and tree characteristics on the RWI responses to climate were investigated using linear mixed-effects models. Elevation greatly modulated the climate–growth associations and it frequently interacted with competition intensity or tree age to differentially influence growth responsiveness to climate. Old trees were more sensitive to climate than young trees, but while old tree’s response to climate highly depended on elevation (e.g. positive influence of summer temperature on old trees’ RWIs at high elevations, but negative effect at low elevations), differences of the young trees’ response across the elevation gradient were less evident. The severity of the past disturbance also modified the climate–growth associations because of contrasting canopy structures. Our results suggest that although an increase in temperature might enhance growth at high elevations, it may also induce growth declines due to drought stress at lower elevations, particularly for old trees or trees growing under high levels of competition, which may increase their vulnerability to disturbances.
    Full-text · Article · Oct 2015
    • "In young and dense stands, competition causes a concentration of growth on the dominant trees, while the canopy gaps in mature and old stands can favour the growth of smaller trees (Binkley, 2004; Binkley et al., 2006). The growth distribution between small and tall trees in forest stands can also vary spatially (Pretzsch and Dieler, 2011) and temporally (Wichmann, 2002) with site conditions. On fertile sites and in years with optimum conditions, growth concentrates strongly on the tall trees as they can better intercept light and suppress smaller neighbours . "
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    ABSTRACT: With a total area of several million hectares, mountain forests of Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.) and European beech (Fagus sylvatica L.) connect the beech-covered lowlands and spruce-dominated alpine regions and still represent the most natural though managed forests in Europe. For sustaining their unique functions and services, their natural gap dynamics are emulated by the combined shelterwood-femel-coupe system. In the 1970s, 22 long-term experimental plots were established in the Bavarian Alps in order to substantiate the formerly mainly experience-based silvicultural prescriptions. After more than 40 years of successive surveys including the integrated evaluation of the old stands and the measurement of natural regeneration, analyses reveal: (1) The reduction of overstorey density is generally associated with a proportional reduction of the overstorey stand growth. So, the recommended 20-40 per cent density reduction of a combined shelterwood-femel coupe may reduce the mean annual increment also by ∼20-40 per cent, but part of this loss is compensated by the additional growth of the regeneration. (2) Over time, the natural regeneration is continuously augmented by new recruitment of seedlings and saplings. (3) However, even 40 years after initiating regeneration, spruce is rare in the regeneration compared with fir, beech and other broadleaved species. Further observation will show whether spruce will catch up with the other species or whether it requires either larger disturbances than gap and femel coupes, or possibly planting. Based on these findings, a refined shelterwood-femel-coupe system is proposed and its advantages and disadvantages are discussed.
    No preview · Article · May 2015 · Forestry
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    • "Modification of stress response by site, thinning, tree, and stand characteristics Site, stand density, thinning, individual crown volume, and social class can affect growth response under drought stress (Pretzsch and Dieler 2011). Site played a crucial role in our investigation. "
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    ABSTRACT: Climate change in Central Europe may come along with acute drought stress, which can severely reduce growth and vitality of forest trees and whole stands. For a tree species such as Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) which is cultivated far beyond its natural range in Europe, knowledge of its behaviour under stress is crucial for the cultivation of Douglas-fir in view of a changing climate. Because of its easy accessibility, growth response to stress was mainly studied based on diameter growth at breast height. In long-term experiments on one dry and one moist site in Southern Germany, stem analyses of 133 mature and even-aged Douglas-firs were performed. The short-term growth reaction pattern under acute drought stress of 2003 had not only consequences on diameter but more pronounced effects can be observed when studying tree height: Respecting the different age trends by previous detrending, height increment only reacted more sensitive on the dry site. We also showed that extrapolating a particular decline in basal area increment to the whole stem can result in misunderstandings. However, results were less biased, when original data were smoothed or short-term assessment of volume growth was based on basal area measurements. By means of a linear mixed model approach, the influence of site, tree, and stand characteristics on Lloret’s indices of resistance and resilience (Lloret et al. in Oikos 120:1909–1920. doi:10.1111/j.1600-0706.2011.19372.x, 2011) were analysed. For Douglas-fir, site played a crucial role and became more important considering the age trend. On the contrary, the positive influence of site quality on drought tolerance decreased with data processing. However, more growing space by thinning can advance tree resistance and resilience regarding height, diameter, and volume growth. Large individual crown volume improved the growth pattern under drought, and large stand density impaired it. Douglas-fir is obviously equipped with a morphological variability, which fosters lateral rather than vertical growth allocation under severe stress. Silviculture can mitigate stress through the choice of the site and through lower stand densities by thinning. Our refined stress response analysis confirmed a favourable growth and resilience of Douglas-fir even under extreme drought events.
    Full-text · Article · Jun 2014 · European Journal of Forest Research
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