Jan Knorn
Humboldt University of Berlin
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Environmental Research Letters | 2013
Camilo Alcántara; Tobias Kuemmerle; Matthias Baumann; Eugenia Bragina; Patrick Griffiths; Patrick Hostert; Jan Knorn; Daniel Müller; Alexander V. Prishchepov; Florian Schierhorn; Anika Sieber; Volker C. Radeloff
The demand for agricultural products continues to grow rapidly, but further agricultural expansion entails substantial environmental costs, making recultivating currently unused farmland an interesting alternative. The collapse of the Soviet Union in 1991 led to widespread abandonment of agricultural lands, but the extent and spatial patterns of abandonment are unclear. We quantified the extent of abandoned farmland, both croplands and pastures, across the region using MODIS NDVI satellite image time series from 2004 to 2006 and support vector machine classifications. Abandoned farmland was widespread, totaling 52.5 Mha, particularly in temperate European Russia (32 Mha), northern and western Ukraine, and Belarus. Differences in abandonment rates among countries were striking, suggesting that institutional and socio-economic factors were more important in determining the amount of abandonment than biophysical conditions. Indeed, much abandoned farmland occurred in areas without major constraints for agriculture. Our map provides a basis for assessing the potential of Central and Eastern Europe’s abandoned agricultural lands to contribute to food or bioenergy production, or carbon storage, as well as the environmental trade-offs and social constraints of recultivation.
Environmental Conservation | 2013
Jan Knorn; Tobias Kuemmerle; Volker C. Radeloff; William S. Keeton; Vladimir Gancz; Iovu-Adrian Biriş; Miroslav Svoboda; Patrick Griffiths; Adrian Hagatis; Patrick Hostert
SUMMARY Old-growth forests around the world are vanishing rapidly and have been lost almost completely from the European temperate forest region. Poor management practices, often triggered by socioeconomic and institutional change, are the main causes of loss. Recent trends in old-growth forest cover in Romania, where some of the last remaining tracts of these forests within Europe are located, are revealed by satellite image analysis. Forest cover declined by 1.3 % from 2000 to 2010. Romania’s protected area network has been expanded substantially since the country’s accession to the European Union in 2007, and most of the remaining old-growth forests now are located within protected areas. Surprisingly though, 72% of the old-growth forest disturbances are found within protected areas, highlighting the threats still facing these forests. It appears that logging in old-growth forests is, at least in part, related to institutional reforms, insufficient protection and ownership changes since the collapse of communism in 1989. The majority of harvesting activities in old-growth forest areas are in accordance with the law. Without improvements to their governance, the future of Romania’s old-growth forests and the important ecosystem services they provide remains uncertain.
Remote Sensing | 2014
Jan Stefanski; Tobias Kuemmerle; Oleh Chaskovskyy; Patrick Griffiths; Vassiliy Havryluk; Jan Knorn; Nikolas Korol; Anika Sieber; Björn Waske
The global demand for agricultural products is surging due to population growth, more meat-based diets, and the increasing role of bioenergy. Three strategies can increase agricultural production: (1) expanding agriculture into natural ecosystems; (2) intensifying existing farmland; or (3) recultivating abandoned farmland. Because agricultural expansion entails substantial environmental trade-offs, intensification and recultivation are currently gaining increasing attention. Assessing where these strategies may be pursued, however, requires improved spatial information on land use intensity, including where farmland is active and fallow. We developed a framework to integrate optical and radar data in order to advance the mapping of three farmland management regimes: (1) large-scale, mechanized agriculture; (2) small-scale, subsistence agriculture; and (3) fallow or abandoned farmland. We applied this framework to our study area in western Ukraine, a region characterized by marked spatial heterogeneity in management intensity due to the legacies from Soviet land management, the breakdown of the Soviet Union in 1991, and the recent integration of this region into world markets. We mapped land management regimes using a hierarchical, object-based framework. Image segmentation for delineating objects was performed by using the Superpixel Contour algorithm. We then applied Random Forest classification to map land management regimes and validated our map using randomly sampled in-situ data, obtained during an extensive field campaign. Our results showed that farmland management regimes were mapped reliably, resulting in a final map with an overall accuracy of 83.4%. Comparing our land management regimes map with a soil map revealed that most fallow land occurred on soils marginally suited for agriculture, but some areas within our study region contained considerable potential for recultivation. Overall, our study highlights the potential for an improved, more nuanced mapping of agricultural land use by combining imagery of different sensors.
Conservation Biology | 2017
Van Butsic; Catalina Munteanu; Patrick Griffiths; Jan Knorn; Volker C. Radeloff; Juraj Lieskovský; Daniel Mueller; Tobias Kuemmerle
Protected areas are a cornerstone for forest protection, but they are not always effective during times of socioeconomic and institutional crises. The Carpathian Mountains in Eastern Europe are an ecologically outstanding region, with widespread seminatural and old-growth forest. Since 1990, Carpathian countries (Czech Republic, Hungary, Poland, Romania, Slovakia, and Ukraine) have experienced economic hardship and institutional changes, including the breakdown of socialism, European Union accession, and a rapid expansion of protected areas. The question is how protected-area effectiveness has varied during these times across the Carpathians given these changes. We analyzed a satellite-based data set of forest disturbance (i.e., forest loss due to harvesting or natural disturbances) from 1985 to 2010 and used matching statistics and a fixed-effects estimator to quantify the effect of protection on forest disturbance. Protected areas in the Czech Republic, Slovakia, and the Ukraine had significantly less deforestation inside protected areas than outside in some periods; the likelihood of disturbance was reduced by 1-5%. The effectiveness of protection increased over time in these countries, whereas the opposite was true in Romania. Older protected areas were most effective in Romania and Hungary, but newer protected areas were more effective in Czech Republic, and Poland. Strict protection (International Union for Conservation of Nature [IUCN] protection category Ia-II) was not more effective than landscape-level protection (IUCN III-VI). We suggest that the strength of institutions, the differences in forest privatization, forest management, prior distribution of protected areas, and when countries joined the European Union may provide explanations for the strikingly heterogeneous effectiveness patterns among countries. Our results highlight how different the effects of protected areas can be at broad scales, indicating that the effectiveness of protected areas is transitory over time and space and suggesting that generalizations about the effectiveness of protected areas can be misleading.
Archive | 2017
Catalina Munteanu; Volker C. Radeloff; Patrick Griffiths; Lubos Halada; Dominik Kaim; Jan Knorn; Jacek Kozak; Tobias Kuemmerle; Juraj Lieskovsky; Daniel Müller; Katarzyna Ostapowicz; Oleksandra Shandra; Premysl Stych
The Carpathian region represents an ideal showcase of several land change theories and their implications for conservation because this region shares the long geo-political and socio-economic history of Eastern Europe while also being a biodiversity hotspot. With a long history of abrupt socio-economic and institutional shifts, the Carpathians exemplify how ecosystems may or may not be pushed into an alternative stable state following shocks such as the collapse of empires, world wars or the collapse of socialism. Furthermore, ecosystem changes may or may not experience time-lags in response to shocks, and over long time periods, historic land-use practices may produce land-use legacies that persist on the landscapes for decades or centuries. Here, we analyze the long-term drivers of land change and their land-use outcomes in the Carpathian region, with a particular focus on forests, agriculture and grasslands, and provide examples of how ecosystems respond to shocks using examples of alternative stable states, time-lags and land-use legacies. Understanding how and why land change patterns vary over time and space is important for balancing land-use decisions, especially in biodiverse regions with a high conservation value.
Remote Sensing of Environment | 2009
Jan Knorn; Andreas Rabe; Volker C. Radeloff; Tobias Kuemmerle; Jacek Kozak; Patrick Hostert
Remote Sensing of Environment | 2009
Tobias Kuemmerle; Oleh Chaskovskyy; Jan Knorn; Volker C. Radeloff; Ivan Kruhlov; William S. Keeton; Patrick Hostert
Biological Conservation | 2012
Jan Knorn; Tobias Kuemmerle; Volker C. Radeloff; Alina Szabo; Marcel Mindrescu; William S. Keeton; Ioan Vasile Abrudan; Patrick Griffiths; Vladimir Gancz; Patrick Hostert
Remote Sensing of Environment | 2012
Patrick Griffiths; Tobias Kuemmerle; Robert E. Kennedy; Ioan Vasile Abrudan; Jan Knorn; Patrick Hostert
Web Ecology | 2014
M. Mikoláö; Miroslav Svoboda; Václav Pouska; Robert C. Morrissey; Daniel C. Donato; William S. Keeton; Thomas A. Nagel; Jörg Müller; Jan Knorn; Laurentiu Rozylowicz; C. M. Enescu; Volodymyr Trotsiuk; Pavel Janda; Hana Mrhalová; Zuzana Michalová; Frank Krumm; D. Kraus; N. Balcescu