Assessing transformation scenarios from pure Norway spruce to mixed uneven-aged forests in mountain areas

Hilmers, Torben; Biber, Peter; Knoke, Thomas; Pretzsch, Hans

doi:10.1007/s10342-020-01270-y

Cited by 46 publications

(41 citation statements)

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“…Examples are the promotion of sessile oak or Scots pine by removal of competing European beech (Stimm et al 2021;Spellmann 2008), promotion of Pyrenean oak when mixed with Scots pine (González-Molina 1996), and release of slower growing Norway spruce when mixed with naturally regenerated birch, aspen, and grey alder (Kairiūkštis 1973). In all the cases, in order to keep the mixtures the light demanding species (such as Scots pine, sessile oak, or European larch) often need a promotion by schematic release or selective treatment (based on negative selection) of neighboring more shade-tolerant species (Hilmers et al 2020).…”

Section: The Main Criteria Of Thinning Interventionsmentioning

confidence: 99%

Silvicultural prescriptions for mixed-species forest stands. A European review and perspective

et al. 2021

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Compared with far-developed measures and methods for mono-specific forest stands, the silvicultural prescriptions for mixed-species stands are at their early beginning. However, they are essential for the well-conceived establishment, design, and control of mixed-species stands, currently promoted in many countries worldwide. Here, we review the state of the art and we further develop silvicultural prescriptions for mixed-species stands for steering of experiments, stand modeling, and silviculture. We review which aspects of tree species mixing are most relevant for management goal achievement. We found the maintenance of species diversity and structural heterogeneity for ecological purpose, stabilizing productivity, and social-economic performance as main objectives. We give an overview of quantitatively formulated silvicultural prescriptions for steering mixed-species stands for forest practice, long-term experiments, forest stand models. Compared with the sophisticated guidelines for mono-specific stands, prescriptions for mixed stand are often mainly qualitative and vague. Then, we introduce methodological approaches in development for steering mixture: measures for spatial and temporal separation, species-specific growing space requirements for crop trees, coefficients for equivalence and density modification, and basic relationships for steering tree number and area-based mixing proportions. Finally, we draw conclusions for further development of methodological approaches for silvicultural steering of experiments, implementation in stand simulators, and for silvicultural operations. We see the need for improving the quantitative spatially explicit rules based at tree or cohort level, for substantiating the knowledge on species-specific allometry, growing area, tree-to-tree distances, and position-dependent competition indices for steering tree removal. We discuss the prospects and limitations of establishing silvicultural prescriptions for mixed-species stands that inevitably will be more complicated than those for mono-specific stands, and we draw conclusions for next steps in science and practice.

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Section: The Main Criteria Of Thinning Interventionsmentioning

confidence: 99%

Silvicultural prescriptions for mixed-species forest stands. A European review and perspective

et al. 2021

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“…Nevertheless, all three tree species can successfully coexist at elevations between ~ 600 and 1400 m a.s.l. and create complex uneven-aged balanced mountain mixed forests (Hilmers et al 2020).…”

Section: Relevance Of the Results For Forest Management And Silviculturementioning

confidence: 99%

“…For prediction, the mean annual temperature and the de Martonne aridity index were kept constant (mean value of each elevation class) development and uneven age distributions (e.g. Pommerening and Murphy 2004;Hilmers et al 2020). The mixture of fir-spruce-beech with an uneven distribution of stem diameters may provide a resilient reference stand type for many forest regions across Europe (Torresan et al 2020).…”

Section: Relevance Of Beech In Mono-specific and Mixed Mountain Forestsmentioning

confidence: 99%

European beech stem diameter grows better in mixed than in mono-specific stands at the edge of its distribution in mountain forests

et al. 2020

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Recent studies show that several tree species are spreading to higher latitudes and elevations due to climate change. European beech, presently dominating from the colline to the subalpine vegetation belt, is already present in upper montane subalpine forests and has a high potential to further advance to higher elevations in European mountain forests, where the temperature is predicted to further increase in the near future. Although essential for adaptive silviculture, it remains unknown whether the upward shift of beech could be assisted when it is mixed with Norway spruce or silver fir compared with mono-specific stands, as the species interactions under such conditions are hardly known. In this study, we posed the general hypotheses that the growth depending on age of European beech in mountain forests was similar in mono-specific and mixed-species stands and remained stable over time and space in the last two centuries. The scrutiny of these hypotheses was based on increment coring of 1240 dominant beech trees in 45 plots in mono-specific stands of beech and in 46 mixed mountain forests. We found that (i) on average, mean tree diameter increased linearly with age. The age trend was linear in both forest types, but the slope of the age–growth relationship was higher in mono-specific than in mixed mountain forests. (ii) Beech growth in mono-specific stands was stronger reduced with increasing elevation than that in mixed-species stands. (iii) Beech growth in mono-specific stands was on average higher than beech growth in mixed stands. However, at elevations > 1200 m, growth of beech in mixed stands was higher than that in mono-specific stands. Differences in the growth patterns among elevation zones are less pronounced now than in the past, in both mono-specific and mixed stands. As the higher and longer persisting growth rates extend the flexibility of suitable ages or size for tree harvest and removal, the longer-lasting growth may be of special relevance for multi-aged silviculture concepts. On top of their function for structure and habitat improvement, the remaining old trees may grow more in mass and value than assumed so far.

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“…Minor thinning not only allows for early timber harvest, but also promotes the growth of retention trees, prevents invasion by alien species and the development of extreme environmental conditions, ensures the structural stability of stands, and maintains ecological services ( Otto et al, 2012 ; Lu et al, 2018 ; Hilmers et al, 2020 ). It is widely used in Chinese fir plantations.…”

Section: Discussionmentioning

confidence: 99%

“…Mixed stands may also be planted from scratch (e.g., Piotto et al, 2004 ; Li et al, 2020 ). Additional measures, such as extending rotation times or closing hillsides to facilitate afforestation, are sometimes used in conjunction with natural processes to promote stand succession ( Li, 2004 ; Cai et al, 2007 ; Hilmers et al, 2020 ). Competition between trees and consequent mortality are inevitable in stand cultivation and natural conditions ( Girona et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

The Abundance and Structure of Deadwood: A Comparison of Mixed and Thinned Chinese Fir Plantations

et al. 2021

Front. Plant Sci.

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The sustainability of coniferous monoculture plantations is facing challenges with respect to yields, ecology, and biodiversity. Conversion of monocultural coniferous plantations into mixed stands using thinning or direct mixed planting is widely considered to be a key strategy for overcoming these challenges and transforming the characteristics of plantations on a regional scale. Substantial amounts of deadwood may be produced in mixed forests (MFs); this material is important for evaluating and modifying forest management methods, understanding the dynamics of forest stands, and achieving biodiversity conservation. We assessed the quantitative characters and diameter distributions of deadwood in mixed and thinned Chinese fir [Cunninghamia lanceolata (Lamb.) Hook.] forests over one rotation. We used the g(r) function and spatial parameters to analyze the spatial structure of deadwood, and used logistic regression and Hegyi’s competition index (HCI) to explore competition and mortality. Our results indicate that: (1) Chinese fir dominated in all groups of deadwood (snags, broken wood, and fallen wood), and the abundance, volume, and mortality rates of deadwood were much lower in the thinning forest compared to the MF. (2) Later coming populations (LCPs) comprised the majority of the small diameter classes in the thinning forest, but only accounted for a small proportion of the MF. (3) Broken wood in the thinning forest was randomly distributed, while the other types of deadwood were clustered at most spatial scales. In contrast, the spatial patterns in the MF were random at most spatial scales. (4) Total deadwood in both stands was in a status of intermediate and was randomly surrounded by its four nearest neighbors. All types of deadwood were highly mixed in the thinning forest and moderately mixed in the MF. Our case study suggests that thinning and mixing result in different stand development processes and thus influence the type, amount, and structure of deadwood. Thinning significantly reduces competition, which is the main driver of tree mortality. Converting pure Chinese fir plantations into mixed stands by thinning should be taken in future. Understanding tree mortality after conversion is essential to select appropriate silvicultural treatments and achieve ultimately sustainable forest management.

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Assessing transformation scenarios from pure Norway spruce to mixed uneven-aged forests in mountain areas

Cited by 46 publications

References 100 publications

Silvicultural prescriptions for mixed-species forest stands. A European review and perspective

Silvicultural prescriptions for mixed-species forest stands. A European review and perspective

European beech stem diameter grows better in mixed than in mono-specific stands at the edge of its distribution in mountain forests

The Abundance and Structure of Deadwood: A Comparison of Mixed and Thinned Chinese Fir Plantations

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