Conference Presentations by Tamara Fetzel
6th symposium on research in protected areas in Salzburg, Austria, 2017
The Greek island of Samothraki has undergone rapid changes in recent decades. The consequences ar... more The Greek island of Samothraki has undergone rapid changes in recent decades. The consequences are a wide variety of environmental but also social problems which the island community is currently facing. One of the major threats is the sharp increase in free roaming small ruminants since the 1960s, which has led to overgrazing, soil erosion and infrastructure destruction (Biel and Tan 2014). This development threatens the conservation goals of the large NATURA 2000 sites and future core area of the planned UNESCO Biosphere Reserve (Fischer-Kowalski et al. 2011), covering more than two thirds of the mountainous island and parts of the adjacent marine area (Fig.1). In this presentation, we focus on our work with the local farming community in order to reduce grazing pressure on the island’s ecosystems and restore areas highly a ected by erosion.
Papers by Tamara Fetzel
Global Change Biology, Jan 10, 2017
Increasing food production is essential to meet the future food demand of a growing world populat... more Increasing food production is essential to meet the future food demand of a growing world population. In the light of pressing sustainability challenges like climate change and the importance of the global livestock system for food security as well as GHG emissions, finding ways to increasing food production sustainably and without increasing competition for food crops is essential. Yet, many unknowns relate to livestock grazing, in particular grazing intensity, an essential variable to assess the sustainability of livestock systems. Here we explore ecological limits to grazing intensity (GI; i.e., the fraction of Net Primary Production consumed by grazing animals) by analysing the role of seasonality in natural grasslands. We estimate seasonal limitations to GI by combining monthly Net Primary Production data and a map of global livestock distribution with assumptions on the length of non-favourable periods that can be bridged by livestock (e.g., by browsing dead standing biomass, storage systems or biomass conservation). This allows us to derive a seasonality-limited potential GI, which we compare with the GI prevailing in 2000. We find that GI in 2000 lies below its potential on 39% of the total global natural grasslands, which has a potential for increasing biomass extraction of up to 181 MtC/yr. In contrast, on 61% of the area GI exceeds the potential, made possible by management. Mobilizing this potential could increase milk production by 5%, meat production by 4%, or contribute to free up to 2.8 Mio km² of grassland area at the global scale if the Accepted Article This article is protected by copyright. All rights reserved. numerous socio-ecological constraints can be overcome. We discuss socio-ecological trade-offs, which may reduce the estimated potential considerably and require the estabilishment of sound monitoring systems and an improved understanding of livestock system's role in the Earth system.
Land Use Policy, Jul 1, 2018
Livestock keeping and food production from grasslands play an important role in the Mediterranean... more Livestock keeping and food production from grasslands play an important role in the Mediterranean region, where grazing has a long tradition and still is a key livelihood strategy. Yet, in many places widespread degradation (caused by overgrazing) severely threatens the natural resource base and prospects for future food security and sustainable development. On Samothraki, a Greek island, several decades of continuous increase of the local livestock population, exceeding not only the local food base by far but also the local farmers' ability to provide supplementary feed, led to a socio-ecological tipping point turning the dynamics downward. Still, in the face of very restricted marketing opportunities, we find local farmers in an economic deadlock of relying on CAP subsidies as a main source of income and on still too high animal numbers for maintaining an ecological balance of their land while lacking the labor power (due to large-scale migration to Germany in the 1950s and 60 s) to apply adequate management practices. In this paper, we present a feed balance (feed-demand and supply) for sheep and goats from 1970 to 2012 and discuss causes and effects of the excessive growth in animal numbers, as well as reasons for their downturn in the last decade. We describe the island's groundcover and symptoms of soil degradation, and underline our findings by reference to a remote sensing approach. Our findings recently gained in prominence as in September 2017, a state of emergency had to be declared on the island when a major weather event triggered a series of landslides that severely damaged the main town, a number of roads and bridges and even the 700 years old Fonias Tower, a marker of Samothraki tourism.
Environmental Research Letters, 2016
Meeting expected surges in global biomass demand while protecting pristine ecosystems likely requ... more Meeting expected surges in global biomass demand while protecting pristine ecosystems likely requires intensification of current croplands. Yet many uncertainties relate to the potentials for cropland intensification, mainly because conceptualizing and measuring land use intensity is intricate, particularly at the global scale. We present a spatially explicit analysis of global cropland use intensity, following an ecological energy flow perspective. We analyze (a) changes of net primary production (NPP) from the potential system (i.e. assuming undisturbed vegetation) to croplands around 2000 and relate these changes to (b) inputs of (N) fertilizer and irrigation and (c) to biomass outputs, allowing for a three dimensional focus on intensification. Globally the actual NPP of croplands, expressed as per cent of their potential NPP (NPPact%), amounts to 77%. A mix of socio-economic and natural factors explains the high spatial variation which ranges from 22.6% to 416.0% within the inner 95 percentiles. NPPact% is well below NPPpot in many developing, (Sub-) Tropical regions, while it massively surpasses NPPpot on irrigated drylands and in many industrialized temperate regions. The interrelations of NPP losses (i.e. the difference between NPPact and NPPpot), agricultural inputs and biomass harvest differ substantially between biogeographical regions. Maintaining NPPpot was particularly N-intensive in forest biomes, as compared to cropland in natural grassland biomes. However, much higher levels of biomass harvest occur in forest biomes. We show that fertilization loads correlate with NPPact% linearly, but the relation gets increasingly blurred beyond a level of 125 kgN ha−1. Thus, large potentials exist to improve N-efficiency at the global scale, as only 10% of global croplands are above this level. Reallocating surplus N could substantially reduce NPP losses by up to 80% below current levels and at the same time increase biomass harvest by almost 30%. However, we also show that eradicating NPP losses globally might not be feasible due to the high input costs and associated sustainability implications. Our analysis emphasizes the necessity to avoid mono-dimensional perspectives with respect to research on sustainable intensification pathways and the potential of integrated socio-ecological approaches for consistently contrasting environmental trade-offs and societal benefits of land use intensification.
Global Change Biology, Sep 22, 2016
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
FACCE MACSUR Reports, Jul 22, 2016
Increasing food production from cropland and grassland is essential to meet the future food deman... more Increasing food production from cropland and grassland is essential to meet the future food demand of a growing world population without further land-use expansion. It is estimated that until 2050, food production has to increase strongly to meet future food demands. Increasing food production from grasslands in a sustainable way (e.g., by not degrading essential ecosystem services) is important, yet requires a good understanding of the major determinants and constraints of the global livestock production systems and the associated socioeconomic and ecological patterns. The spatially explicit analysis of grazing intensity (GI; e.g., the fraction of available Net Primary Production (NPP) that is consumed by grazing animals in a year) using monthly data allow us to analyse the role of seasonality for limits to grazing intensity. Seasonality creates in many regions of the world shortage and surplus periods of NPP, which can (partly) be overcome by social organization, such as the employment of storage technologies or by imports. By comparing the current livestock density to the ecologically maximum density (EMD) determined by biomass availability during shortage periods we show that management has contributed to substantial higher livestock density in many world-regions whereas in others it is still close to the EMD. Our analysis shows to which expense (e.g., length of shortage period to overcome) the increase in livestock-density comes in different world regions and where potential for further biomass extraction exists. This study contributes to an improved understanding of the systemic inter-linkages between GI, seasonal biomass supply, and socioeconomic and ecological trade-offs, and provides essential information for analyzing intensification potentials of grasslands.
Regional Environmental Change, Nov 18, 2015
Abstract African land systems play a decisive role in addressing future sustainability challenges... more Abstract African land systems play a decisive role in addressing future sustainability challenges for food and energy supply—in Africa and potentially elsewhere. Knowledge on the magnitude and efficiency of current land use and its socio-economic frame conditions is scarce but required to provide an appropriate basis for estimating production potentials and efficiency improvements. We apply the human appropriation of net primary production (HANPP) framework to analyze African land systems and their dynamics between 1980 and 2005. HANPP measures human-induced changes in ecological biomass flows and allows analyzing the efficiency with which humans use the natural resource NPP (Net Primary Production). In 2005, African HANPP amounts to 20 %, which is below the global average of 23 %, and has grown significantly (+55 %) since 1980. HANPP efficiency (i.e., the ratio of used biomass extraction to total HANPP) is low (35 %) in contrast to the global average of 48 %. Large regional variations (ranging from 18 % in Central Africa to >100 % in Northern Africa) and only small improvements of +11 % on average have been observed. In the study period, the growth of HANPP has been mostly driven by land-use expansion. We conclude that the observed low HANPP efficiency in Africa suggests that there may be potentials for improving the efficiency of biomass production on existing land-uses rather than increasing output trough further land expansion. We discuss policy implications that could help better utilizing existing potentials to increase land-use efficiency in a sustainable manner.
The Greek island of Samothraki has undergone rapid changes in recent decades. The consequences ar... more The Greek island of Samothraki has undergone rapid changes in recent decades. The consequences are a wide variety of environmental but also social problems which the island community is currently facing. One of the major threats is the sharp increase in free roaming small ruminants since the 1960s, which has led to overgrazing, soil erosion and infrastructure destruction (Biel and Tan 2014). This development threatens the conservation goals of the large NATURA 2000 sites and future core area of the planned UNESCO Biosphere Reserve (Fischer-Kowalski et al. 2011), covering more than two thirds of the mountainous island and parts of the adjacent marine area (Fig.1). In this presentation, we focus on our work with the local farming community in order to reduce grazing pressure on the island’s ecosystems and restore areas highly a ected by erosion.
Global Change Biology, 2016
Table S1. Selected management activities. The review focusses on the individual management activi... more Table S1. Selected management activities. The review focusses on the individual management activities in the flagged ecosystem types. Management activity Definition Closed forest Open woodlands Grazing land Cropland Wetlands Forestry harvest Extraction of woody biomass (mainly boles, but also bark and branches), by means of clear cutting or selective cutting x x Tree species selection Selection of tree species by means of planting of tree seedlings x Grazing and mowing harvest Herbaceous biomass extraction, mainly by roaming ruminant livestock, or by mowing appliances x x Crop harvest and crop residue management
Environmental Research Letters, 2016
Meeting expected surges in global biomass demand while protecting pristine ecosystems likely requ... more Meeting expected surges in global biomass demand while protecting pristine ecosystems likely requires intensification of current croplands. Yet many uncertainties relate to the potentials for cropland intensification, mainly because conceptualizing and measuring land use intensity is intricate, particularly at the global scale. We present a spatially explicit analysis of global cropland use intensity, following an ecological energy flow perspective. We analyze (a) changes of net primary production (NPP) from the potential system (i.e. assuming undisturbed vegetation) to croplands around 2000 and relate these changes to (b) inputs of (N) fertilizer and irrigation and (c) to biomass outputs, allowing for a three dimensional focus on intensification. Globally the actual NPP of croplands, expressed as per cent of their potential NPP (NPPact%), amounts to 77%. A mix of socio-economic and natural factors explains the high spatial variation which ranges from 22.6% to 416.0% within the inner 95 percentiles. NPPact% is well below NPPpot in many developing, (Sub-) Tropical regions, while it massively surpasses NPPpot on irrigated drylands and in many industrialized temperate regions. The interrelations of NPP losses (i.e. the difference between NPPact and NPPpot), agricultural inputs and biomass harvest differ substantially between biogeographical regions. Maintaining NPPpot was particularly N-intensive in forest biomes, as compared to cropland in natural grassland biomes. However, much higher levels of biomass harvest occur in forest biomes. We show that fertilization loads correlate with NPPact% linearly, but the relation gets increasingly blurred beyond a level of 125 kgN ha−1. Thus, large potentials exist to improve N-efficiency at the global scale, as only 10% of global croplands are above this level. Reallocating surplus N could substantially reduce NPP losses by up to 80% below current levels and at the same time increase biomass harvest by almost 30%. However, we also show that eradicating NPP losses globally might not be feasible due to the high input costs and associated sustainability implications. Our analysis emphasizes the necessity to avoid mono-dimensional perspectives with respect to research on sustainable intensification pathways and the potential of integrated socio-ecological approaches for consistently contrasting environmental trade-offs and societal benefits of land use intensification.
Regional Environmental Change, 2015
Abstract African land systems play a decisive role in addressing future sustainability challenges... more Abstract African land systems play a decisive role in addressing future sustainability challenges for food and energy supply—in Africa and potentially elsewhere. Knowledge on the magnitude and efficiency of current land use and its socio-economic frame conditions is scarce but required to provide an appropriate basis for estimating production potentials and efficiency improvements. We apply the human appropriation of net primary production (HANPP) framework to analyze African land systems and their dynamics between 1980 and 2005. HANPP measures human-induced changes in ecological biomass flows and allows analyzing the efficiency with which humans use the natural resource NPP (Net Primary Production). In 2005, African HANPP amounts to 20 %, which is below the global average of 23 %, and has grown significantly (+55 %) since 1980. HANPP efficiency (i.e., the ratio of used biomass extraction to total HANPP) is low (35 %) in contrast to the global average of 48 %. Large regional variations (ranging from 18 % in Central Africa to >100 % in Northern Africa) and only small improvements of +11 % on average have been observed. In the study period, the growth of HANPP has been mostly driven by land-use expansion. We conclude that the observed low HANPP efficiency in Africa suggests that there may be potentials for improving the efficiency of biomass production on existing land-uses rather than increasing output trough further land expansion. We discuss policy implications that could help better utilizing existing potentials to increase land-use efficiency in a sustainable manner.
Regional Environmental Change, 2015
Understanding patterns, dynamics, and drivers of land use is crucial for improving our ability to... more Understanding patterns, dynamics, and drivers of land use is crucial for improving our ability to cope with sustainability challenges. The human appropriation of net primary production (HANPP) framework provides a set of integrated socio-ecological indicators that quantify how land use alters energy flows in ecosystems via land conversions and biomass harvest. Thus, HANPP enables researchers to systematically and consistently assess the outcome of changes in land cover and land-use intensity across spatio-temporal scales. Yet, fine-scale HANPP assessments are so far missing, an information important to address site-specific ecological implications of land use. Here, we provide such an assessment for Europe at a 1-km scale for the years 1990, 2000, and 2006. The assessment was based on a consistent land-use/biomass flow dataset derived from statistical data, remote sensing maps, and a dynamic global vegetation model. We find that HANPP in Europe amounted to *43 % of potential productivity, well above the global average of *25 %, with little variation in the European average since 1990. HANPP was highest in Central Europe and lower in Northern and Southern Europe. At the regional level, distinct changes in land-use intensity were observed, most importantly the decline of cropland areas and yields following the breakdown of socialism in Eastern Europe and the subsequent recovery after 2000, or strong dynamics related to storm events that resulted in massive salvage loggings. In sum, however, these local dynamics cancelled each other out at the aggregate level. We conclude that this finding warrants further research into aspects of the scale-dependency of dynamics and stability of land use.
Ecological Economics, 2014
This study presents a national level analysis of changes in land use and land cover in New Zealan... more This study presents a national level analysis of changes in land use and land cover in New Zealand from 1860 to 2005. We employ the Human Appropriation of Net Primary Production (HANPP) framework to assess land use induced impacts on ecological energy flows by accounting for socioeconomic harvest and productivity losses through land use change. By analyzing the interplay of socioeconomic dynamics, changes in land use, land use efficiency, and ecosystems we distinguish four stages of land use dynamics: 1) between 1860 and 1920 HANPP increased from 34% to 53% of the potential Net Primary Production, accompanied by low HANPP efficiency. 2) After 1920, driven by legislation that ended deforestation, HANPP declined to 32.7%, and then stagnated until 1950. 3) This was followed by a new period of growth which ended in 1980, when HANPP had reached 41%. Increased agricultural inputs resulted in increasing HANPP efficiency between 1920 and 1965, when high subsidization and land expansion caused stagnation in this trend. 4) After 1980, HANPP declined and reached 32% by 2005, reflecting efficiency improvements. We discuss these observed trajectories in the context of socioeconomic dynamics such as land use policies and trade.
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Conference Presentations by Tamara Fetzel
Papers by Tamara Fetzel