Thunen Institute for World Forestry

Hamburg, Germany

Thunen Institute for World Forestry

Hamburg, Germany

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Giordani P.,University of Genoa | Stofer S.,Swiss Federal Institute of forest | Seidling W.,Thunen Institute of Forest Ecosystems | Granke O.,Institute For Digitale Systemanalyse And Landschaftsdiagnose | Fischer R.,Thunen Institute for World Forestry
Forest Ecology and Management | Year: 2014

Lichens are considered to be among the most sensitive organisms for several types of pollutants. In this work, we analyzed a dataset of 286 epiphytic lichen species observed on 1155 trees at 83 ForestBIOTA plots, which is a subsample of approx. 500 plots of the European ICP Forests Level II network. We aimed at examining the amount of nitrogen deposition for which a significant variation of the relative diversity of morpho-functional groups of epiphytic lichens in the sampled plots is expected. Moreover, the study aimed at determining how much variance of these diversity variables could be explained by nitrogen depositions only. We used correlation and multiple regression models as well as hierarchical partitioning to evaluate the relative importance of environmental predictors in explaining variation in lichen diversity descriptors. The analysis splits the variation explained by each variable into a joint effect together with the other explanatory variables, and into an independent effect not shared with any other variable. The percentage of macrolichens in the plots was shown to be the most important indicator, since 56.7% of its variation could be explained by deposition, particularly by nitrogen compounds. It was shown that approx. 75% of the ForestBIOTA plots are affected by an unsustainably high throughfall nitrogen deposition. Based on these outcomes, it was possible to determine a nitrogen critical load of 2.4kgha-1yr-1. © 2013 Elsevier B.V.


Veresoglou S.D.,Free University of Berlin | Veresoglou S.D.,Berlin Brandenburg Institute of Advanced Biodiversity Research BBIB | Penuelas J.,CSIC | Fischer R.,Thunen Institute for World Forestry | And 6 more authors.
New Phytologist | Year: 2014

Understanding the relationship between nitrogen (N) availability and stand health in forest ecosystems is crucial, because a large proportion of European forests is subjected to N-deposition levels beyond their retention capacity. We used data from a long-term forest monitoring programme (ICP Forests) to test the relationship between an index of N availability, foliar nitrogen : phosphorus (N : P) ratios, tree defoliation and discoloration. We hypothesized a segmented response of stand health to N : P ratios and an improved model-fit after correcting for climatic covariates. In accordance with the hypothesis, we found a segmented response with a breakpoint for conifer defoliation at N : P ratios as low as 7.3. Inclusion of climatic variables improved the fit of the models, but there was significant collinearity with N : P. Increases in N availability appear, at least for conifers, to have a negative effect on tree health even under N-limiting conditions. Regulation of N-deposition levels is consequently as timely as ever. We propose that increases in tree defoliation, other than resulting in serious plant fitness issues, may represent early diagnostic symptoms of N-addition related imbalances. © 2014 New Phytologist Trust.


Mikkelsen T.N.,Technical University of Denmark | Clarke N.,Norwegian Forest And Landscape Institute | Danielewska A.,University of Life Sciences in Poznań | Fischer R.,Thunen Institute for World Forestry
Developments in Environmental Science | Year: 2013

Consequences of climate change in combination with air pollution for ecosystem services are multiple but hard to predict. To meet future challenges, a way forward is development of supersites in forest research. This chapter will elucidate the development of existing European forest monitoring and research infrastructures, describe harmonisation of databases and knowledge about climate change and air pollution impact on forest ecosystems and present knowledge gap statements from fifty experts affiliated with the COST FP0903 Action. The statements are structured within the following subjects: The carbon cycle in forests (LULUCF accounting), forest health and vitality, forest biodiversity, extent of forest resources, availability of wood and forest biomass, protective functions of forests and socio-economic information about the forest sector. This will provide a base of knowledge with regard to supersites in forest ecosystem monitoring and research. © 2013 Elsevier Ltd.


Vitale M.,University of Rome La Sapienza | Proietti C.,University of Rome La Sapienza | Cionni I.,ENEA | Fischer R.,Thunen Institute for World Forestry | De Marco A.,ENEA
Water, Air, and Soil Pollution | Year: 2014

Defoliation is one of the most important parameters monitored in the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests). Defoliation is an indicator for forest health and vitality. Conventional statistical analysis shows weak or not significant correlations between tree crown defoliation and climatic conditions or air pollution parameters, because of its high variability. The study aims to evaluate the most important factors among climatic, pollutants (Nox and NHy) and stand parameters affecting crown defoliation of the main European tree species (Fagus sylvatica, Picea abies, Quercus ilex, Pinus sylvestris and Quercus petraea) through application of a new and powerful statistical classifier, the random forests analysis (RFA). RFA highlighted that tree crown defoliation was mainly related to age in P. abies, to geographic location in F. sylvatica and to air pollution predictors in Q. ilex, while it was similarly linked to meteorological and air pollution predictors in P. sylvestris and Q. petraea. In this study, RFA has proven to be, for the first time, a useful tool to discern the most important predictors affecting tree crown defoliation, and consequently, it can be used for an appropriate forest management. © Springer International Publishing 2014.


Danielewska A.,University of Life Sciences in Poznań | Paoletti E.,CNR Plant Protection Institute | Clarke N.,Norwegian Forest And Landscape Institute | Olejnik J.,University of Life Sciences in Poznań | And 10 more authors.
Forest Systems | Year: 2013

Aim of study: The main aim of the work was to summarize availability, quality and comparability of on-going European Research and Monitoring Networks (ERMN), based on the results of a COST FP0903 Action questionnaire carried out in September 2010 and May 2012. Area of study: The COST Action FP0903 involves 29 European countries and 4 non-COST institutions from USA, Morocco and Tunisia. In this study, the total of 22 replies to the questionnaire from 18 countries were included. Materials and methods: Based on the feedback from the Action FP0903 countries, the most popular European Networks were identified. Thereafter, the access to the network database, available quality assurance/quality control procedures and publication were described. Finally, the so-called "Supersites" concept, defined as a "highly instrumented research infrastructure, for both research and monitoring of soil-plant-atmosphere interactions" was discussed. Main results: The result of the survey indicate that the vast majority of the Action FP0903 countries participate in the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forest (ICP Forest). The multi-disciplinary International Cooperative Programme on Integrated Monitoring of Air Pollution Effects on Ecosystems (ICPIM) is the second most widespread forest programme. Research highlights: To fully understand biochemical cycles in forest ecosystems, long-term monitoring is needed. Hence, a network of "Supersites", is proposed. The application of the above infrastructure can be an effective way to attain a better integration of research and monitoring networks at forest sites in Europe.

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