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.
2021
Authors
Volkmar TimmermannAbstract
No abstract has been registered
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, 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 species in two closed-canopy forests in the native range (Ontario, Canada) and introduced range (Baden-Württemburg, Germany). In the native range, Q. rubra allocated a greater proportion of biomass to roots, while in the introduced range, growth and allocation patterns favored the development of leaves. Q. rubra seedlings had greater annual increases in height, diameter and biomass in the introduced range. Q. rubra seedlings in the introduced range were also younger; however, they had a mean area per leaf and a total leaf area per seedling that were five times greater than seedlings in the native range. Such differences in morphological traits and allocation patterns support the hypothesis that Q. rubra expresses greater shade tolerance in the introduced range, and that natural regeneration of Q. rubra is not as limited by shade 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 study over a greater geographical range in native and introduced ecosystems, and examine the genetic and environmental bases of observed differences in plant traits.
Authors
Mélanie Spedener Anders Nielsen Marie Vestergaard Henriksen Gunnar Austrheim Karen Marie Mathisen Barbara ZimmermannAbstract
No abstract has been registered
Abstract
To hundre mjølkebruk i Midt-Norge blei delt i tre nesten like store grupper; 'Låg' (68 gardar), 'Medium' (67 gardar) og 'Høg' (68 garder), etter årleg tildeling av kraftfôr til mjølkekyrne for å teste effekten av kraftfôrnivå på indikatorar for miljøpåverknad og økonomisk lønsemd. Gjennomsnittleg årleg kraftfôrnivå per ku var 15,4, 18,8 og 21,7 GJ nettoenergi laktasjon (NEL) og årleg avdrått i energikorrigert mjølk (EKM) per ku var 7868, 8421 og 8906 kg i høvesvis 'Låg', ‘Medium’og ‘Høg’. Standard livsløpsanalyse og dekningsbidrag blei brukt til å bestemme indikatorar for miljøpåverknad og økonomiske resultat av mjølk- og kjøttproduksjon. Den funksjonelle eininga var mengde 2,78 MJ spiseleg energi, tilsvarande 1,0 kg EKM eller 0,42 kg kjøtt eller en kombinasjon av mjølk og kjøtt som utgjer 2,78 MJ, altså EKM ekvivalent i mjølk og kjøtt levert EKM-eq. Det globale oppvarmingspotensialet, energiintensiteten og nitrogenintensiteten var i gjennomsnitt 1,46 kg CO2- eq./kg EKM-eq., 5,61 MJ energibruk/kg EKM-eq., og 6,83 N input/N-produkt, og var ikkje forskjellig mellom gruppene. Gardar med ‘Låg’ kraftfôrtildeling brukte mindre areal av total arealbruk til dyrking av innkjøpt fôr utanfor garden enn de i ‘Høg’ (0,39 vs. 0,46 daa/daa), men det totale arealet som blei brukt per kg EKM-eq. var større ('Låg' 3,24 vs. 'Høg' 2,84 m2/kg EKM-eq.). Dekningsbidraget per kg EKM-eq. levert var i gjennomsnitt høgare på 'Låg' gardar (6,57 NOK/kg EKM-eq.) enn 'Medium' (6,04 NOK/ kg EKM-eq.) og 'Høg' (5,73 NOK/kg ECM-eq.). Vår analyse viser at høgare kraftfôrnivå ikkje alltid gir mindre global oppvarmingspotensiale og mengd fossil energi per kg mjølk og kjøtt produsert samanlikna med lågare kraftfôrnivå.
Abstract
No abstract has been registered
Abstract
Plant virus eradication is a prerequisite for the use of virus-free propagules for sustainable crop production. In contrast, virus preservation is required for all types of applied and basic research of viruses. Shoot tip cryopreservation can act as a double-edged strategy, facilitating either virus eradication or virus preservation in cryoderived plants. Here, we tested the efficacies of shoot tip cryopreservation for virus eradication and preservation in shallot (Allium cepa var. aggregatum). In vitro stock shallot shoots infected with onion yellow dwarf virus (OYDV) and shallot latent virus were thermotreated for 0, 2, and 4 weeks at a constant temperature of 36℃ before shoot tip cryopreservation. Results showed that viruses were preserved in recovered shoots when thermotherapy was not applied. Although thermotherapy lowered the regrowth levels of cryotreated shoot tips, the efficiency of virus eradication increased from 5% to 54%. Immunolocalization of OYDV and histological observation of cryotreated shoot tips showed the high frequency of virus preservation was due to the viral invasion of cells close to the apical meristem and the high proportion of cells surviving. Four weeks of thermotherapy drastically decreased the distribution of OYDV, as well as the percentage of surviving cells within the shoot tips, thereby promoting virus eradication. Virus-free plants obtained from combining thermotherapy with cryotherapy showed significantly improved vegetative growth and bulb production. The present study reports how thermotherapy can act as a trigger to facilitate either the safe preservation of Allium viruses or the production of virus-free shallot plants.
Authors
Wenjun Zhou Jing Zhu Hongli Ji John Grace Liqing Sha Qinghai Song Yuntong Liu Xiaolong Bai Youxing Lin Jinbo Gao Xuehai Fei Ruiwu Zhou Jianwei Tang Xiaobao Deng Guirui Yu Junhui Zhang Xunhua Zheng Junbin Zhao Yiping ZhangAbstract
With large area of primary tropical rainforest converted into rubber (Hevea brasiliensis) plantation in Southeast Asia, it is necessary to examine the change in soil CO2 and CH4 emissions, and their underlying drivers in tropical rainforest (TRF) and rubber plantation. In TRF and RP in Xishuangbanna Southwest China, we measured the soil CO2 , CH4 , temperature, and water content once each week from 2003 to 2008, and twice weeks in 2013 and 2014. Additionally, the concentrations of soil carbon (C) and nitrogen (N) fractions from 2013 to 2014 were observed. Inputs of litter and live, dead, decomposed fine roots dynamics were also included. TRF transplanted to RP did not change significantly the annual soil CO2 emissions (TRF, 359 ± 91 and RP 352 ± 41 mg CO2 m−2 h−1) but decreased soil CH4 uptake significantly (TRF, −0.11 ± 0.18 mg CH4 m−2 h−1) RP, −0.020 ± 0.087 mg CH4 m−2 h−1). The most important influence on soil CO2 and CH4 emissions in the RP was the leaf area index and soil water content, respectively, whereas the soil water content, soil temperature, and dead fine roots were the most important factors in the TRF. Variations in the soil CO2 and CH4 caused by land-use transition were individually explained by soil temperature and fine root growth and decomposition, respectively. The results show that land-use change varied the soil CH4 and CO2 emission dynamics and drivers by the variation of soil environmental and plant's factors.
Authors
Björn Ringselle Benedikte Watne Oliver Therese With Berge Inger Sundheim Fløistad Liv Berge Lars Olav BrandsæterAbstract
Many herbaceous perennial plant species gain significant competitive advantages from their underground creeping storage and proliferation organs (CR), making them more likely to become successful weeds or invasive plants. To develop efficient control methods against such invasive or weedy creeping perennial plants, it is necessary to identify when the dry weight minimum of their CR (CR DWmin) occurs. Moreover, it is of interest to determine how the timing of CR DWmin differs in species with different light requirements at different light levels. The CR DWmin of Aegopodium podagraria, Elymus repens and Sonchus arvensis were studied in climate chambers under two light levels (100 and 250 μmol m−2 s−1), and Reynoutria japonica, R. sachaliensis and R. × bohemica under one light level (250 μmol m−2 s−1). Under 250 μmol m−2 s−1, the CR DWmin occurred before one fully developed leaf in R. sachaliensis, around 1–2 leaves in A. podagraria and E. repens and around four leaves in S. arvensis, R. japonica and R. × bohemica. In addition to reducing growth in all species, less light resulted in a higher shoot mass fraction in E. repens and S. arvensis, but not A. podagraria; and it delayed the CR DWmin in E. repens, but not S. arvensis. Only 65% of planted A. podagragra rhizomes produced shoots. Beyond the CR DWmin, Reynoutria spp. reinvested in their old CR, while the other species primarily produced new CR. We conclude that A. podagraria, R. sachaliensis and E. repens are vulnerable to control efforts at an earlier developmental stage than S. arvensis, R. japonica and R. × bohemica.
Authors
Habtamu AlemAbstract
No abstract has been registered
Abstract
No abstract has been registered