Christian Kuehne

Research Scientist

(+47) 485 06 725
christian.kuehne@nibio.no

Place
Ås H8

Visiting address
Høgskoleveien 8, 1433 Ås

Biography

Education

  • Dr. forest. Göttingen University, Germany (2004)
  • M.Sc. Göttingen University, Germany (2002)
  • B.Sc. Göttingen University, Germany (2000)

Professional Experience

Prior to NIBIO I worked as Postdoctoral Research Associate at Oregon State University, USA (2005-2006) and Göttingen University, Germany (2007), as Lecturer at Freiburg University, Germany (2007-2013), and as Research Associate at the University of Maine, USA (2013-2020).
 
My research activities have covered the silvicultural manipulation of regeneration and growth dynamics of mixed species forests, limitations of the close-to-nature forest management paradigm in Central Europe, the ecology and silviculture of oak forests, as well as modeling the influence of forest management practices on stand dynamics and forest structure.

Selected publications

Nosko P, Moreau K, Kuehne C, Major KC, Bauhus J. 2021. Does a shift in shade tolerance as suggested by seedling morphology explain differences in regeneration success of northern red oak in native and introduced ranges? J For Res. In press.
 
Kern CC, Kenefic LS, Kuehne C, Weiskittel AR, Kaschmitter SJ, D’Amato AW, Dey DC, Kabrick JM, Palik BJ, Schuler TM. 2021. Relative influence of stand and site factors on aboveground live-tree carbon sequestration and mortality in managed and unmanaged forests. For Ecol Manage 492: 119266.
 
Mäkinen H, Henttonen HM, Kohnle U, Kuehne C, Nöjd P, Yue C, Klädtke J, Siipilehto J. 2021. Site carrying capacity of Norway spruce and Scots pine stands has increased in Germany and northern Europe. For Ecol Manage 492: 119214.
 
Kohler M, Pyttel P, Kuehne C, Modrow T, Bauhus J. 2020. On the knowns and unknowns of natural regeneration of silviculturally managed sessile oak (Quercus petraea (Matt.) Liebl.) forests – a literature review. Ann For Sci. 77: 101.
 
Kuehne C, Pyttel P, Modrow T, Kohnle U, Bauhus J. 2020. Seedling development and regeneration success after ten years following group selection harvesting in a sessile oak (Quercus petraea (Matt.) Liebl.) stand. Ann For Sci 77: 71.
 
Modrow T, Kuehne C, Saha S, Bauhus J, Pyttel PL. 2020. Photosynthetic performance, height growth, and dominance of naturally regenerated sessile oak (Quercus petraea [Mattuschka] Liebl.) seedlings in small-scale canopy openings of varying sizes. Eur J For Res 139: 41–52.
 
Kuehne C, Russell MB, Weiskittel AR, Kershaw Jr. JA. 2020. Comparing strategies for representing individual-tree secondary growth in mixed-species stands in the Acadian Forest region. For Ecol Manage 459: 117823.
 
Weiskittel AR, Kuehne C. 2019. Evaluating and modeling variation in site-level maximum carrying capacity of mixed-species forest stands in the Acadian Region of northeastern North America. For Chron 95(03): 171-182.
 
Kuehne C, Weiskittel AR, Legaard KR, Simons-Legaard EM. 2019. Development and comparison of various stand- and tree-level modeling approaches to predict harvest occurrence and intensity across the mixed forests in Maine, northeastern US. Scan J For Res. 34(8): 739-750.
 
Puhlick JJ, Kuehne C, Kenefic LS. 2019. Crop tree growth response and quality after silvicultural rehabilitation of cutover stands. Can J For Res 49(6): 670-679.
 
Kuehne C, Weiskittel AR, Waskiewicz J. 2019. Comparing performance of contrasting distance-independent and distance-dependent competition metrics in predicting individual tree diameter increment and survival within structurally-heterogeneous, mixed-species forests of Northeastern United States. For Ecol Manage 433: 205–216.
 
Kuehne C, Puhlick J, Weiskittel A, Cutko A, Cameron D, Sferra N, Schlawin J. 2018. Metrics for comparing stand structure and dynamics between Ecological Reserves and managed forest of Maine, USA. Ecology 99: 2876.
 
Kuehne C, Weiskittel AR, Pommerening A, Wagner RG. 2018. Evaluation of 10-year temporal and spatial variability in structure and growth across contrasting commercial thinning treatments in spruce-fir forests of northern Maine, USA. Ann For Sci 75: 20.
 
Bose AK, Weiskittel AR, Kuehne C, Wagner RG, Turnblom E, Burkhart HE. 2018. Tree-level growth and survival following commercial thinning of four major softwood species in North America. For Ecol Manage 427: 355-364.
 
Bose AK Weiskittel AR, Kuehne C, Wagner RG, Turnblom E, Burkhart HE. 2018. Does commercial thinning improve stand-level growth of the three most commercially important softwood forest types of North America? For Ecol Manage 409: 683-693.
 
Drössler L, Fahlvik N,  Wysocka NK, Hjelm K, Kuehne C. 2017. Natural regeneration in a multi-layered Pinus sylvestris-Picea abies forest after target diameter harvest and soil scarification. Forests 8: 35.
 
Saha S, Kuehne C, Bauhus J. 2017. Lessons learned from oak cluster planting trials in central Europe. Can J For Res 47: 139-148.
 
Bose A, Weiskittel AR, Wagner RG, Kuehne C. 2016. Assessing the factors influencing natural regeneration patterns in the diverse, multi-cohort, and managed forests of Maine, USA. J Veg Sci 27: 1040-1050.
 
Weiskittel A, Kuehne C, McTague JP, Oppenheimer M. 2016. Development and evaluation of an individual tree growth and yield model for the mixed species forest of the Adirondacks Region of New York, USA. For Ecosyst 3: 26.
 
Kuehne C, Weiskittel AR, Wagner RG, Roth BE. 2016. Development and evaluation of individual tree- and stand-level approaches for predicting spruce-fir response to commercial thinning in Maine, USA. For Ecol Manage 376: 84-95.
 
Annighöfer P, Ameztegui A, Ammer C, Balandier P, Bartsch N, Bolte A, Coll L, Collet C, Ewald J, Frischbier N, Gebereyesus T, Haase J, Hamm T, Hirschfelder B, Huth F, Kändler G, Kahl A, Kawaletz H, Kuehne C, Lacointe A, Lin N, Löf M, Malagoli P, Marquier A, Müller S., Promberger S, Provendier D, Röhle H, Sathornkich J, Schall P, Scherer-Lorenzen M, Schröder J, Seele C, Weidig J, Wirth C, Wolf H, Wollmerstädt J, Mund M. 2016. Species-specific and generic biomass equations for seedlings and saplings of European tree species. Eur J For Res 135: 313-329.
 
Kuehne C, Karrie C, Forrester DI, Kohnle U, Bauhus J. 2015. Root system development in naturally regenerated Douglas-fir saplings as influenced by canopy closure and crowding. J For Sci 61: 406-415.
 
Kuehne C, Weiskittel AR, Fraver S, Puettman KJ. 2015. Effects of thinning induced changes in structural heterogeneity on growth, ingrowth, and mortality in secondary coastal Douglas-fir forests. Can J For Res 45: 1448-1461.
 
Kühne C, Jacob A, Gräf M. 2014. The practice of establishing and tending oak (Qercus petraea [Matt.] Liebl., Q. robur L.) stands – An interview-based study in the eastern Upper Rhine Plain, Germany. Forstarchiv 85: 179-187. In German
 
Saha S, Kuehne C, Bauhus J. 2014. Intra- and interspecific competition differently influence growth and stem quality of young oaks (Quercus robur L. and Q. petraea (Mattuschka) Liebl.). Ann For Sci 71: 381-393
 
Kuehne C, Nosko P, Horwath T, Bauhus J. 2014. A comparative study of physiological and morphological seedling traits associated with shade tolerance in introduced red oak (Quercus rubra L.) and native hardwood tree species in southwestern Germany. Tree Physiol 34: 184-193
 
Saha S, Kuehne C, Bauhus J. 2013. Tree species richness and stand productivity in low-density cluster plantings with oaks (Quercus robur and Q. petraea). Forests 4: 650-655
 
Kuehne C, Kublin E, Pyttel P, Bauhus J. 2013. Growth and form of Quercus robur and Fraxinus excelsior respond distinctly different to initial growing space: results from 24-year-old Nelder experiments. J For Res 24: 1-14
 
Major KC, Nosko P, Kuehne C, Campbell D, Bauhus J. 2013. Regeneration dynamics of non-native northern red oak (Quercus rubra L.) populations as influenced by environmental factors: a case study in managed hardwood forests of south-western Germany. For Ecol Manage 291: 144-153
 
Bauhus J, Puettmann KJ, Kühne C. 2013. Is close-to-nature forest management in Europe compatible with managing forests as complex ecosystems? In Messier C., Puettmann K., and Coates K.D. (eds.) Managing forests as complex adaptive systems. Building resilience to the challenge of global change. Routledge Abingdon, pp. 187-213
 
Briggs N, Kuehne C, Kohnle U, Bauhus J. 2012. Root system response of naturally regenerated Douglas-fir (Pseudotsuga menziesii) after complete overstory removal. Can J For Res 42: 1858-1864
 
Saha S, Kuehne C, Kohnle U, Brang P, Ehring A, Geisel J, Leder B, Muth M, Petersen R, Peter J, Ruhm W, Bauhus J. 2012. Growth and quality of young oaks (Quercus robur and Q. petraea) grown in cluster plantings in Central Europe: a weighted meta-analysis. For Ecol Manage 283: 106-118
 
Kühne C, Bauhus J, Hörnig T, Oh S. 2011. Effects of canopy closure, crowding and plant size on root system development in Douglas-fir saplings. Forstarchiv 82: 184-194. In German
 
Kuehne C, Donath C, Müller-Using SI, Bartsch N. 2008. Nutrient fluxes via leaching from coarse woody debris in a Fagus sylvatica forest in the Solling Mts., Germany. Can J For Res 38: 2405-2413
 
Kuehne C, Puettmann KJ. 2008. Natural regeneration in thinned Douglas-fir stands in western Oregon. J Sust For 27: 246-274
 
Kühne C, Bartsch N. 2007. Germination of acorns and development of oak seedlings (Quercus robur L.) following flooding. J For Sci 53: 391-399
 
Kühne C, Puettmann KJ. 2006. Large scale management experiments – new approaches to silvicultural research. Forstarchiv 77: 102-109. In German
 
Kühne C, Bartsch N, Röhrig E. 2005. Silvicultural management of floodplain forests of the Upper Rhine Valley in special consideration of Quercus robur L. Schriften aus der Forstlichen Fakultät der Universität Göttingen und der Niedersächsichen Forstlichen Versuchsanstalt 140. J.D. Sauerländer’s Verlag Frankfurt am Main. 139 p. In German
 
Kühne C, Bartsch N. 2005. Fructification and seedling development of pedunculate oak (Quercus robur) in floodplain forests of the Upper Rhine Valley. Forstarchiv 76: 16-23. In German
 
Kühne C, Bartsch N. 2004. On the natural regeneration of mixed stands of European beech (Fagus sylvatica) and Norway spruce (Picea abies) in the Solling Mts., Germany. Forst u. Holz 58: 3-7. In German
 
 

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Abstract

Across North America, forests dominated by Quercus rubra L. (northern red oak), a moderately shade-tolerant tree species, are undergoing successional replacement by shade-tolerant competitors. Under closed canopies, Q. rubra seedlings are unable to compete with these shade-tolerant species and do not recruit to upper forest strata. In Europe, natural regeneration of introduced Q. rubra is often successful despite the absence of fire disturbances, which promotes regeneration in the native range. Considering that understorey light availability is a major factor affecting recruitment of seedlings, we hypothesized that Q. rubra seedlings are more shade tolerant in the introduced range than in the native range. Morphological traits and biomass allocation patterns of seedlings indicative of shade tolerance were compared for Q. rubra and three co-occurring native tree species in two closed-canopy forests in each of native range (Ontario, Canada) and introduced range (Baden-Württemburg, Germany). In the native range, Q. rubra allocated a greater proportion of total biomass to roots, while in the introduced range, growth and allocation patterns favored the development of leaves to a greater extent. Under closed canopies, Q. rubra seedlings exhibited greater annual increases in height, diameter and biomass in the introduced range. Here, Q. rubra seedlings were younger; however, had a mean area per leaf and a total leaf area per seedling that were both five times greater than seedlings in the native range. Such differences in morphological traits and allocation patterns support the hypothesis that Q. rubra is expressing greater shade tolerance in the introduced range and that natural regeneration of Q. rubra is not as limited by shade here as in the native range. The ability of Q. rubra seedlings to grow faster under closed canopies in Europe may explain the discrepancy in regeneration success of this species in native and introduced ranges. Future research should confirm findings of this case study over a greater geographical range in native and introduced ecosystems and examine the genetic and environmental bases of observed differences in plant traits.

To document

Abstract

We compiled data from several independent, long-term silvicultural studies on USDA Forest Service experimental forests across a latitudinal gradient in the northeastern and north-central U.S.A. to evaluate factors influencing aboveground live-tree carbon sequestration and mortality. Data represent five sites with more than 70,000 repeated tree records spanning eight decades, five ecoregions, and a range of stand conditions. We used these data to test the relative influence of factors such as climate, treatment history (uneven-aged or no management), species composition, and stand structural conditions on aboveground live-tree carbon sequestration and mortality in repeatedly measured trees. Relative to no management, we found that uneven-aged management tended to have a positive effect on carbon sequestration at low stocking levels and in areas of favorable climate (expressed as a combination of growing season precipitation and annual growing degree days > 5 ◦C). In addition, losses of carbon from the aboveground live-tree pool due to tree mortality were lower in managed than unmanaged stands. These findings suggest that there may be conditions at which rate of sequestration in living trees is higher in stands managed with uneven-aged silviculture than in unmanaged stands, and that this benefit is greatest where climate is favorable.

To document

Abstract

The maximum size-density relationship describes site carrying capacity, i.e., the maximum number of trees of a given size that can be stocked per unit area (self-thinning line). We analysed whether the self-thinning lines of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) have remained unchanged over time in South Germany, Norway and Finland, i.e., over a wide climatic gradient from Central Europe up to the Arctic circle. The analyses are based on long-term growth and yield experiments measured on individual tree basis over several decades, the oldest experiments established during the early 20th century. The stochastic frontier analysis was used to analyse changes in the species-specific self-thinning lines. The results show that the self-thinning lines have shifted upwards over time in all the regions. Thus, currently stands sustain higher stand densities than in the past. The increase of the maximum density for a given average stem size was more pronounced for pine than for spruce, but similar in all studied geographical regions. In addition, increasing site index was associated with increasing site carrying capacity for spruce and pine in all regions. The results imply that environmental changes have altered site properties in similar fashion across the whole study region. In practical forestry, increased site carrying capacity will reduce mortality and loss of growing stock.

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Abstract

Key message This literature review identified the main factors for the success of different silvicultural approaches to regenerate sessile oak naturally and unveiled at the same time important knowledge gaps. Most previous studies were only short-term and restricted to a few factors and single locations. Hence, the findings of these studies are of limited explanatory power and do not allow to develop general, widely applicable management recommendations. Context Successful natural regeneration of sessile oak (Quercus petraea (Matt.) Liebl.) through silvicultural actions depends on a number of biotic, abiotic and management factors and their interactions. However, owing to a limited understanding about the influence of these critical factors, there is great uncertainty about suitable silvicultural approaches for natural oak regeneration, in particular regarding the size of canopy openings and speed of canopy removal. Aims This study aimed at critically evaluating documented information on natural regeneration of sessile oak. Specifically, we identified (i) the factors that determine the success of approaches for natural regeneration and (ii) evaluated the evidence base associated with different silvicultural approaches. Methods A comprehensive literature search was done considering relevant peer-reviewed publications of ISI-listed journals as well as non-ISI listed published papers and reports by practitioners. Out of more than 260 collected references, a set of 53 silvicultural ‘core publications’ was identified and analyzed using a catalogue of numeric and categorical evaluation criteria. Results The most important factors determining regeneration success extracted from the literature were light availability, presence of competing vegetation, initial oak seedling density, browsing of seedlings and intensity of stand tending measures. However, the review revealed also great uncertainty regarding the interactions between these factors and the magnitude of their influence. Most studies were of short duration and restricted to single locations. In only 20% of the experimental studies, the observation period exceeded five years. Total costs of regeneration efforts were quantified and reported in only two studies. This lack of data on the expenses of different approaches to natural oak regeneration appears to be one of the most crucial knowledge deficits revealed in this literature review. Conclusion Natural regeneration of sessile oak may be achieved under a wide range of canopy openings, if competing vegetation and browsing is negligible, seedling density is high and tending to remove competing vegetation is carried out consistently. However, since the silvicultural regeneration success depends on the interactions among these factors, which have often not been adequately considered, we caution against general recommendations for silvicultural systems developed from case studies and call for new long-term studies with comprehensive experimental designs.

To document

Abstract

Key message This study showed that regeneration success (presence of oaks ≥ 150 cm in total height) in artificial canopy openings of a mature mixed sessile oak stand was mainly driven by initial oak seedling density. Context Small-scale harvesting methods as practiced in close-to-nature forestry may disadvantage the regeneration of more light-demanding tree species including sessile oak (Quercus petraea [Mattuschka] Liebl.) and thus cause regeneration failure. However, owing to the short-term nature of many previous studies, regeneration success of sessile oak could not be properly ascertained. Aims This study examined oak seedling development over a time period of ten growing seasons in canopy openings of 0.05 to 0.2 ha in size created through group selection harvesting in a mature mixed sessile oak forest in southwestern Germany. We tried to answer the following research questions: (i) how do initial stand conditions relate to and interact with oak seedling density and seedling height growth, and (ii) what are the driving factors of regeneration success under the encountered site conditions. Methods We evaluated the influence of solar radiation, Rubus spp. cover, initial oak seedling density, and competition from other tree species on change in density and height of oak seedlings, as well as overall regeneration success (oak seedlings ≥ 150 cm in height). Results Regeneration success increased with initial oak seedling density and solar radiation levels and decreased with early Rubus spp. cover. Density and maximum height of oak seedlings was negatively related with competition of other woody species. Conclusion Results of our longer-term study demonstrate that forest management activities to regenerate sessile oak naturally are only successful in stands (i) without advance regeneration of other woody species and without established, recalcitrant ground vegetation, (ii) with a sufficiently high initial oak seedling density in larger patches following mast years, and (iii) where periodic monitoring and control of competing woody individuals can be ensured. Our findings further corroborate the view that natural regeneration of sessile oak in small-scale canopy openings is possible in principle.