Comparison between the productivity of pure and mixed stands of Norway spruce and European beech along an ecological gradient

Abstract

Abstract• Existing growth and yield plots of pure and mixed stands of Norway spruce (Picea abies (L.) H. Karst.) and European beech (Fagus sylvatica L.) were aggregated in order to unify the somewhat scattered sources of information currently available, as well as to develop a sound working hypothesis about mixing effects. The database contains information from 23 long-term plots, covering an ecological gradient from nutrient poor and dry to nutrient rich and moist sites throughout Central Europe.• An empirically formed interaction model showed, that depending on the site conditions, dry mass growth in mixed stands can range from −46% to +138 % of the growth yielded by a scaled combination of pure stands at equal mixing proportions.• Drawing from the interaction model, overyielding of the mixed stands appears to be triggered by two separate mechanisms. On poor sites, where significant overyielding is commonly found, facilitation by beech offsets nutrient-related growth limitations in spruce. In contrast, overyielding of mixed stands occurs less frequently on rich sites, and appears to be based on an admixture effect, with spruce reducing the severe intra-specific competition common in pure beech stands.• It was concluded that silviculture can accelerate growth of spruce by beech admixtures on poor sites, while growth of beech can be promoted by admixture of spruce, particularly on excellent sites.

Influence of thinning intensity and canopy type on Scots pine stand and growth dynamics in a mixed managed forest

“…Several studies on the effects of mixture on the forest yield have been carried out (e.g. Kelty, 1992;Pretzsch, 2005;Pretzsch & Schütze, 2009;Pretzsch et al, 2010), but little is known about inter-specific processes in mixed Scots pine (Pinus sylvestris L.)-beech (Fagus sylvatica L.) forests, and particularly in Mediterranean areas (but see Primicia et al, 2013;Río et al, 2014). Spiecker (2003) suggested that the structure of mixed stands may be maintained and improved by management practices like thinning, which has been also recommended as a necessary first step in the conversion process from pure Scots pine plantation to mixed broadleaved forests (Crecente-Campo et al, 2009).…”

Red Alder-Conifer Stands in Alaska: An Example of Mixed Species Management to Enhance Structural and Biological Complexity

“…Developing or maintaining alder beyond the young regenerating forested ecosystems as demonstrated here will likely affect associated plant and animal species, populations and communities, and ecosystem structure and function. Previous studies in Britain and Ireland indicated that mixed tree species plantation forests can support higher biodiversity and greater structural diversity than simple single-species forests [25][26][27]30,150]. Humphrey [6] provides a comprehensive review dealing with the possibility and consequences of creating older forests and mixed species stands in Sitka spruce plantations in Britain, and he concluded that spruce plantations are an excellent candidate for such conversions and they develop old-growth conditions faster than many native tree species forests.…”

“…However, the specific benefits are still being investigated and while uncertainty regarding the benefits of these admixtures may persist, there is good evidence for the short-term potential value in these stands. Spruce growth can be improved in mixed stands with beech compared to pure stands on similar substrates [29], and Pretzsch et al [30] reported an accelerated growth of spruce by beech admixtures on poor sites. These results agree with a meta-analysis of boreal and northern temperate forests, which found that mixed tree species were as productive as monoculture forests, while having increased resistance to pest damage over monoculture forests [31].…”

Response of Fagus sylvatica and Picea abies to the interactive effect of neighbor identity and enhanced CO2 levels

“…The awareness of developing adaptive forest management strategies is mainstream in Europe and worldwide (Bolte et al 2009). However, contrasting results exist regarding whether mixed plantations can achieve greater productivity than monocultures (Pretzsch and Schütze 2009;Pretzsch et al 2010). And the consideration of a lower profitability of mixed-forest than monocultures is widespread among stakeholders and forest economists (Knoke et al 2008).…”

“…However, the long term sustainability of mixed stands depends on factors such as species identity or site conditions that can define the net outcome of mixing different species (Pretzsch et al 2010). In addition, available information on how different species in mixed-forest responds to concurrent biotic interaction under predicted scenarios of climate change, such as the increase of atmospheric CO 2 , is much more limited (Geßler et al 2007;IPCC 2007;Smith et al 2013b).…”