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.
2004
Authors
Paivi Liisa Rinne Carl Gunnar Fossdal Sissel Torre Heather Danforth Aksel Granhus Gunnhild Søgaard John Einset Harald Kvaalen Øystein Johnsen Christiaan van der SchootAbstract
No abstract has been registered
Authors
Lars Sandved Dalen Heather Danforth John Einset Carl Gunnar Fossdal Aksel Granhus Harald Kvaalen Nina Elisabeth Nagy Paivi Liisa Rinne Linda Ripel Sissel Torre Gunnhild Søgaard Christiaan van der SchootAbstract
No abstract has been registered
2003
Abstract
Establishment, survival and height growth of sown and naturally regenerated Picea abies (L.) Karst. seedlings were examined in a 6 yr period in eight stands on bilberry woodland in south- east Norway. Five harvesting treatments (shelterwoods of high, medium and low density, 253/25 m patch-cut, 503/50 m clear-cut) and three scarification alternatives (unscarified, patch scarification, inverting) were combined in a split-plot design. Establishment, survival and plant height after 6 yrs were positively affected by scarification. Significant differences between patch scarification and inverting were not observed, although mortality tended to be lower, and seedlings slightly taller, after patch scarification. Establishment after natural seedfall was least successful on the clear-cut, but more or less equal at the other stand treatments. Height growth increased with decreasing overstorey retention, while there was a tendency towards lower survival on the clear-cuts and patch-cuts. Natural regeneration in the unscarified plots was unsuccessful after 6 yrs, while the different combinations of harvesting and scarification treatments usually gave sufficient regeneration.
Authors
Yi He Jixi Gao Haiying Liu Zhengtao Liu Feng Liu Xiaoshan Zhang Jingheng Guo Yanhui Wang He Shang Pengtao Yu Jianhua Zhu Jingjun Han Bin Yao Xiyon Hu Xiaoquan Zhang Min Shao Limin Zeng Lei Jin Lei Duan Quanru Liu Dawei Zhao Dongbao Zhang Shengliang Chen Renjun Xiang Yi Chang Jinhong Zhang Jiahai Luo Zhanyi Zhang Jinsong Xiao Xiaoyu Peng Rolf David Vogt Hans Martin Seip Wenche Aas Kjetil Tørseth Jan Mulder Trine Sogn Odd Eilertsen Tonje Økland Harald Bratli Valter Angell Svein Solberg Tor Myking Espen Lydersen Thorjørn Larssen Dagang TangAbstract
Sulphur deposition is high at all IMPACTS sites and exceed maximum levels observed in Europe and North-America. Dry deposition equals or exceeds wet deposition. The IMPACTS data, in particular those from the remote Lei Gong Shan site clearly document long-range transport of air pollutants. Due to the actual and future energy combustion and emission strategy in China, the long-range transport of air pollutants may significantly increase with subsequent increased environmental damage in rural and remote areas in China. In addition to sulphur deposition, depositions of reactive nitrogen (nitric acid and ammonia) and calcium are also important and clearly demonstrate that pH alone is not a good indicator for acid deposition. High concentrations of ground level ozone, above critical levels for vegetation and forest, are observed at the Liu Xi He site in Guangdong province. Soil acidification gives rise to high concentrations of toxic aluminium in soil water at several sites. At the Tie Shan Ping site in Chongqing aluminium occurs at a level where long-term harmful effects on trees might be expected. Defoliation and mortality have been severe, however, fairly stable. Insect attacks are apparently a major cause, but enhanced insect attacks might be an indirect effect of health weakening due to acidification. Defoliation has been considerable also in Liu Chong Guan in Guiyang, while the three other catchments had minor defoliation only. High foliar nitrogen concentrations are seen in Lei Gong Shan in Guizhou and Cai Jia Tang in Hunan, accompanied by low P/N-ratios. Statistical tests of vegetation change, so far only implemented in Liu Chong Guan, revealed minor changes in number and abundances of vascular plants, but a significant decline in number of bryophytes. This decline is probably related to climatic year-to-year variations. Data from other catchments and longer time periods are needed to identify vegetation changes related to soil acidification or direct effects of air pollutants. Modelling results from Tie Shan Ping suggest that the currently planned 20% reduction in sulphur emissions is far from sufficient to avoid further acidification. As more data are generated, dose-response relationships, critical load estimates and model predictions will obviously be improved.
Abstract
Mortality, injury and height growth of planted Picea abies (L.) Karst. were examined in a six-year period in eight stands in southeast Norway. There were four residual stand densities (shelterwoods of high, medium and low density, 25 x 25 m patch cut) combined with three scarification treatments (unscarified, patch scarification, inverting) in a split-plot design. Mortality was generally low during the experimental period, and did not differ significantly between the residual density treatments (mean=11.1%). Both survival and plant height after 6 years were improved by inverting, while patch scarification was intermediate but not significantly different from the unscarified alternative. The patch-cutting resulted in the tallest plants, while only minor differences in height growth were found between the shelterwood treatments. The frequency of injured plants after six years was not significantly affected by the treatments (mean=10.6%). The improved plant establishment with inverting in this study is in agreement with previous studies on clear-cuts.
Abstract
The rationale for stand growth modelling is often either grounded in a search for improved scientific understanding or in support for management decisions. The ultimate goal under the first task is seen in mechanistic models, i.e. models that represent the stand structure realistically and predict future growth as a function of the current status of the stand. Such mechanistic models tend to be over-parameterized with respect to the data actually available for a given stand. Calibration of these models may lead to non-unique representations and unreliable predictions. Empirical models, the second major line of growth modelling, typically match available data sets as well as do process-based models. They have less degrees of freedom, hence mitigate the problem of non-unique calibration results, but they employ often parameters without physiological or physical meaning. That is why empirical models cannot be extrapolated beyond the existing conditions of observations. Here we argue that this widespread dilemma can be overcome by using interactive models as an alternative approach to mechanistic (algorithmic) models. Interactive models can be used at two levels: a) the interactions among trees of a species or ecosystem and b) the interactions between forest management and a stand structure, e.g. in thinning trials. In such a model data from a range of sources (scientific, administrative, empirical) can be incorporated into consistent growth reconstructions. Interactive selection among such growth reconstructions may be theoretically more powerful than algorithmic automatic selection. We suggest a modelling approach in which this theoretical conjecture can be put to a practical test. To this end growth models need to be equipped with interactive visualization interfaces in order to be utilized as input devices for silvicultural expertise. Interactive models will not affect the difficulties of predicting forest growth, but may be at their best in documenting and disseminating silvicultural competence in forestry.
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No abstract has been registered
Authors
Holger LangeAbstract
No abstract has been registered
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