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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2020

Abstract

Identification of stocktype attributes that speed up field establishment has potential to reduce rotation time of Christmas tree productions. Such morphological and physiological attributes can be targeted in the nursery production. This study tested the effects of container type and nursery seedling density on stocktype attributes at planting and the effects of these on field performance over two years in Abies lasiocarpa and A. nordmanniana Christmas tree stock. Nursery conditions had a considerable impact on seedling attributes at planting. Although sets of these correlated stocktype attributes contributed to forecast field performance, the predictive power was low. No simple relationships were found between plant biomass, stem diameter or height at planting and biomass at final harvest in either of the two species under the range of stocktype variation and field conditions tested. Contrary, stem diameter and stem height at planting explained some of the responses in stem diameter and height after two years in the field. Thus, any target seedling approach would have to be based on a combined set of stocktype attributes exploring more productive stocktypes. The differences observed between stocktypes were largely due to size differences and ontogenetic drift, and stocktypes converged towards a similar field phenotype over time.

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Abstract

Growth of CO2 concentration level has strong interactions with forests. Forests are able to sequester carbon (C) through photosynthesis and can help to mitigate the effects of climate warming, as well as to reduce the CO2 concentration in the atmosphere. Drought and other extreme weather conditions play a key role in ecosystem functioning and the C-cycle. The eddy covariance (EC) method can be used to better understand forest ecosystems CO2 exchange by directly measuring net carbon and water fluxes. In our study, EC results for measurement of fluxes between the atmosphere and forest canopy are reported for the study period from May to August 2018 in Järvselja, Estonia. Stand-replacing disturbance (clear-cutting) took place in April 2013. The young forest stand is dominated by Norway spruce (Picea abies) and birch (Betula spp.). Findings so far include (1) a C-budget for the study period that showed a slight C-sink status; (2) net ecosystem exchange (NEE) was −0.0084 µmol m−2 s−1 indicating C-uptake during the measurement period; (3) in May, June, July and August, NEE was −0.027, −0.015, 0.001 and 0.006 µmol m−2 s−1, respectively; (4) NEE fluxes are lower in drought conditions and are affected by temperature that averaged 15 °C.

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Abstract

Controlled crosses were made on clones in a seed orchard and the pollination bags were kept on the branches until the cones were harvested. Cones after open pollination were collected at the same time. Seedlings from the controlled pollinations, from open pollination of the same maternal parent and from commercial provenances were grown in growth chambers and terminal bud set was recorded after short day treatments. The seedlings from the seeds of cones that were kept in the pollination bags had a significantly later bud set then expected based on comparisons with their half-sibs from open pollination. The difference corresponds to a decrease in altitude of 100 m at provenance level. It can be caused by epigenetic effects due to temperature differences inside and outside the bags during seed maturation.