Jukka Lippu. (1994). Patterns of dry matter partitioning and 14C-photosynthate allocation in 1.5-year-old Scots pine seedlings. Silva Fennica vol. 28 no. 3 article id 5529. https://doi.org/10.14214/sf.a9169

Keywords: Pinus sylvestris; carbon; photosynthesis; root growth; allocation; shoot growth; 14C-incorporation; dry matter partitioning

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Change in dry matter partitioning, ¹⁴C-incorporation, and sink ¹⁴C-activity of 1.5-year-old Scots pine (Pinus sylvestris L.) seedlings grown in growth chamber conditions were studied during a 91-day experiment. On five sampling dates, seedlings were labelled with ¹⁴CO₂ and whole-plant allocation patterns were determined. Intensively growing shoots modified the dry matter partitioning: during shoot growth the proportion of roots decreased but after that it increased. Based on their large proportion of dry matter, the needles (excluding current needles) were the strongest sink of carbon containing 40% of the incorporated ¹⁴C. Despite their small initial sink size, the elongating shoots (current main shoot + current branch) and their needles were the second strongest sink (30–40% of the total ¹⁴C) which reflects their high physiological activity. The proportion of ¹⁴C in the current year’s main shoot increased during shoot growth but decreased as the growth began to decline after 70 days. 10–20% of the total assimilated ¹⁴C was translocated to the roots. Laterals above 2nd order were the strongest sink in the root system, containing twice as much ¹⁴C as the other roots together. Alternation between shoot and root growth can be seen clearly: carbon allocation to roots was relatively high before and after the period of intensive shoot growth. Changes in root sink strength resulted primarily from changes in root sink activity rather than sink size.

Lippu, E-mail: jl@mm.unknown

Category : Research article

article id 243, category Research article

Rupert Seidl, Werner Rammer, Petra Lasch, Franz-Werner Badeck, Manfred J. Lexer. (2008). Does conversion of even-aged, secondary coniferous forests affect carbon sequestration? A simulation study under changing environmental conditions. Silva Fennica vol. 42 no. 3 article id 243. https://doi.org/10.14214/sf.243

Keywords: forest management; Norway spruce; climate change mitigation; PICUS; 4C; model comparison

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To circumvent problems associated with even-aged, pure coniferous stands propagated outside their natural range alternative management strategies and conversion programs are currently discussed in Central Europe. However, a mainstreaming of such adapted silvicultural systems with climate change mitigation objectives is missing to date. In this study the objective was to assess in situ C storage under conditions of climate change in a secondary Norway spruce (Picea abies (L.) Karst.) forest management unit in Austria. Four management strategies (Norway spruce age class forestry, transition to continuous cover forestry with Norway spruce, conversion to mixed conifer/broadleaved stands, no management) were investigated under current climate and two transient climate change scenarios in a simulation study. By comparing the results of two independent forest ecosystem models (PICUS v1.41, 4C) applied under identical forcings and boundary conditions we aimed at addressing uncertainties in model-based projections. A transition to continuous cover forestry increased C storage in all climate scenarios (+45.4 tC·ha^–1 to +74.0 tC·ha^–1 over the 100 year analysis period) compared to the approximately balanced C budget under the age class system. For the mixed conifer/broadleaved management variant predictions of the two models diverged significantly (+29.4 tC·ha^–1 and –10.6 tC·ha^–1 in PICUS and 4C respectively, current climate). With regard to climate change impacts both models agreed on distinct effects on productivity but lower sensitivity of C stocks due to compensation from respiration and adaptive harvest levels. In conclusion, considering the potential effects of silvicultural decisions on C stocks climate change mitigation should be addressed explicitly in programs advocating targeted change in management paradigms.

Seidl, Institute of Silviculture, BOKU, Vienna, Austria E-mail: rupert.seidl@boku.ac.at
Rammer, Institute of Silviculture, BOKU, Vienna, Austria E-mail: wr@nn.at
Lasch, Potsdam Institute for Climate Impact Research e.V., Potsdam, Germany E-mail: pl@nn.de
Badeck, Potsdam Institute for Climate Impact Research e.V., Potsdam, Germany E-mail: fwb@nn.de
Lexer, Institute of Silviculture, BOKU, Vienna, Austria E-mail: mjl@nn.at

article id 696, category Research article

Jukka Lippu. (1998). Redistribution of 14C-labelled reserve carbon in Pinus sylvestris seedlings during shoot elongation. Silva Fennica vol. 32 no. 1 article id 696. https://doi.org/10.14214/sf.696

Keywords: Scots pine; root growth; carbon storage; 14C labelling; photosynthates; shoot growth

Abstract | View details | Full text in PDF | Author Info

This study examined the later use of 14C reserves formed in previous autumn in Scots pine (Pinus sylvestris L.) seedlings. The seedlings were allowed to photosynthesise 14CO2 in early September when shoot and needle growth was over. The following spring the seedlings were harvested in five samplings during the shoot growth period. The distribution and concentration of 14C were determined and the results were compared with the growth data. It was observed that reserves were not used markedly for the new growth. Most of the 14C was found in one-year-old needles (30–40%) and in the root system (40–50%) which was due to both their high activity as a storage sink and their large sink size. The high initial 14C-activity in the finest roots decreased indicating respiration of reserves. Only a small percent of the reserve carbon was found in the new shoots which indicated that reserves are of minor importance in building a new shoot. An allocation of about 15% of the autumn storage to the stem suggested that in seedlings the stem is of minor importance as a storage organ.

Lippu, Department of Forest Ecology, P.O. Box 24 (Unioninkatu 40 B), FIN-00014 University of Helsinki, Finland E-mail: jukka.lippu@helsinki.fi

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