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Irene Marzolff
Department of Physical Geography Goethe University Frankfurt am Main Frankfurt am Main Germany

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Original research
Published: 07 July 2021 in Remote Sensing in Ecology and Conservation
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Non-forest ecosystems, dominated by shrubs, grasses and herbaceous plants, provide ecosystem services including carbon sequestration and forage for grazing, and are highly sensitive to climatic changes. Yet these ecosystems are poorly represented in remotely sensed biomass products and are undersampled by in situ monitoring. Current global change threats emphasize the need for new tools to capture biomass change in non-forest ecosystems at appropriate scales. Here we developed and deployed a new protocol for photogrammetric height using unoccupied aerial vehicle (UAV) images to test its capability for delivering standardized measurements of biomass across a globally distributed field experiment. We assessed whether canopy height inferred from UAV photogrammetry allows the prediction of aboveground biomass (AGB) across low-stature plant species by conducting 38 photogrammetric surveys over 741 harvested plots to sample 50 species. We found mean canopy height was strongly predictive of AGB across species, with a median adjusted R2 of 0.87 (ranging from 0.46 to 0.99) and median prediction error from leave-one-out cross-validation of 3.9%. Biomass per-unit-of-height was similar within but different among, plant functional types. We found that photogrammetric reconstructions of canopy height were sensitive to wind speed but not sun elevation during surveys. We demonstrated that our photogrammetric approach produced generalizable measurements across growth forms and environmental settings and yielded accuracies as good as those obtained from in situ approaches. We demonstrate that using a standardized approach for UAV photogrammetry can deliver accurate AGB estimates across a wide range of dynamic and heterogeneous ecosystems. Many academic and land management institutions have the technical capacity to deploy these approaches over extents of 1–10 ha−1. Photogrammetric approaches could provide much-needed information required to calibrate and validate the vegetation models and satellite-derived biomass products that are essential to understand vulnerable and understudied non-forested ecosystems around the globe.

ACS Style

Andrew M. Cunliffe; Karen Anderson; Fabio Boschetti; Richard E. Brazier; Hugh A. Graham; Isla H. Myers‐Smith; Thomas Astor; Matthias M. Boer; Leonor G. Calvo; Patrick E. Clark; Michael D. Cramer; Miguel S. Encinas‐Lara; Stephen M. Escarzaga; José M. Fernández‐Guisuraga; Adrian G. Fisher; Kateřina Gdulová; Breahna M. Gillespie; Anne Griebel; Niall P. Hanan; Muhammad S. Hanggito; Stefan Haselberger; Caroline A. Havrilla; Phil Heilman; Wenjie Ji; Jason W. Karl; Mario Kirchhoff; Sabine Kraushaar; Mitchell B. Lyons; Irene Marzolff; Marguerite E. Mauritz; Cameron D. McIntire; Daniel Metzen; Luis A. Méndez‐Barroso; Simon C. Power; Jiří Prošek; Enoc Sanz‐Ablanedo; Katherine J. Sauer; Damian Schulze‐Brüninghoff; Petra Šímová; Stephen Sitch; Julian L. Smit; Caiti M. Steele; Susana Suárez‐Seoane; Sergio A. Vargas; Miguel Villarreal; Fleur Visser; Michael Wachendorf; Hannes Wirnsberger; Robert Wojcikiewicz. Global application of an unoccupied aerial vehicle photogrammetry protocol for predicting aboveground biomass in non‐forest ecosystems. Remote Sensing in Ecology and Conservation 2021, 1 .

AMA Style

Andrew M. Cunliffe, Karen Anderson, Fabio Boschetti, Richard E. Brazier, Hugh A. Graham, Isla H. Myers‐Smith, Thomas Astor, Matthias M. Boer, Leonor G. Calvo, Patrick E. Clark, Michael D. Cramer, Miguel S. Encinas‐Lara, Stephen M. Escarzaga, José M. Fernández‐Guisuraga, Adrian G. Fisher, Kateřina Gdulová, Breahna M. Gillespie, Anne Griebel, Niall P. Hanan, Muhammad S. Hanggito, Stefan Haselberger, Caroline A. Havrilla, Phil Heilman, Wenjie Ji, Jason W. Karl, Mario Kirchhoff, Sabine Kraushaar, Mitchell B. Lyons, Irene Marzolff, Marguerite E. Mauritz, Cameron D. McIntire, Daniel Metzen, Luis A. Méndez‐Barroso, Simon C. Power, Jiří Prošek, Enoc Sanz‐Ablanedo, Katherine J. Sauer, Damian Schulze‐Brüninghoff, Petra Šímová, Stephen Sitch, Julian L. Smit, Caiti M. Steele, Susana Suárez‐Seoane, Sergio A. Vargas, Miguel Villarreal, Fleur Visser, Michael Wachendorf, Hannes Wirnsberger, Robert Wojcikiewicz. Global application of an unoccupied aerial vehicle photogrammetry protocol for predicting aboveground biomass in non‐forest ecosystems. Remote Sensing in Ecology and Conservation. 2021; ():1.

Chicago/Turabian Style

Andrew M. Cunliffe; Karen Anderson; Fabio Boschetti; Richard E. Brazier; Hugh A. Graham; Isla H. Myers‐Smith; Thomas Astor; Matthias M. Boer; Leonor G. Calvo; Patrick E. Clark; Michael D. Cramer; Miguel S. Encinas‐Lara; Stephen M. Escarzaga; José M. Fernández‐Guisuraga; Adrian G. Fisher; Kateřina Gdulová; Breahna M. Gillespie; Anne Griebel; Niall P. Hanan; Muhammad S. Hanggito; Stefan Haselberger; Caroline A. Havrilla; Phil Heilman; Wenjie Ji; Jason W. Karl; Mario Kirchhoff; Sabine Kraushaar; Mitchell B. Lyons; Irene Marzolff; Marguerite E. Mauritz; Cameron D. McIntire; Daniel Metzen; Luis A. Méndez‐Barroso; Simon C. Power; Jiří Prošek; Enoc Sanz‐Ablanedo; Katherine J. Sauer; Damian Schulze‐Brüninghoff; Petra Šímová; Stephen Sitch; Julian L. Smit; Caiti M. Steele; Susana Suárez‐Seoane; Sergio A. Vargas; Miguel Villarreal; Fleur Visser; Michael Wachendorf; Hannes Wirnsberger; Robert Wojcikiewicz. 2021. "Global application of an unoccupied aerial vehicle photogrammetry protocol for predicting aboveground biomass in non‐forest ecosystems." Remote Sensing in Ecology and Conservation , no. : 1.

Preprint content
Published: 19 April 2021
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The endemic argan tree (Argania spinosa) populations in South Morocco are highly degraded due to overbrowsing, illegal firewood extraction and the expansion of intensive agriculture. Bare areas between the isolated trees increase due to limited regrowth, but show lower soil quality than their neighbouring tree areas. Hypothetically, spatial differences of soil quality of the intertree area should result from translocation of litter or soil particles (by runoff and erosion or wind drift) from canopy-covered areas to the intertree areas. 385 soil samples were taken around the tree from the trunk along the tree drip line (within and outside the tree area) as well as the intertree area between two trees in four directions (upslope, downslope and in both directions parallel to the slope) and analysed for soil moisture, pH, electrical conductivity, percolation stability, total nitrogen content, content of soil organic carbon and C / N ratio. 74 tension-disc infiltrometer experiments were performed near the tree drip line, within and outside the tree area, to measure the unsaturated hydraulic conductivity. We found that the tree influence on its surrounding intertree area is limited, with e.g., Corg- & N-content decreasing significantly from tree trunk to tree drip line. However, intertree areas near the tree drip line differed significantly from intertree areas between two trees, yet only with a small effect. Trends for spatial patterns could be found in eastern and downslope directions due to wind drift and slope wash. Soil moisture was highest in the north due to shade from the midday sun, the influence extended to the intertree areas. The unsaturated hydraulic conductivity also showed significant differences between areas within and outside the tree area near the tree drip line. Although only limited influence of the tree on its intertree area was found, the spatial pattern around the tree suggests that reforestation measures should be aimed around tree shelters in northern or eastern directions with higher soil moistures, N- or Corg-content to ensure seedling survival.

ACS Style

Mario Kirchhoff; Tobias Romes; Irene Marzolff; Manuel Seeger; Ali Aït Hssaine; Johannes B. Ries. Spatial patterns of argan-tree influence on soil quality of intertree areas in open woodlands of South Morocco. 2021, 2021, 1 -26.

AMA Style

Mario Kirchhoff, Tobias Romes, Irene Marzolff, Manuel Seeger, Ali Aït Hssaine, Johannes B. Ries. Spatial patterns of argan-tree influence on soil quality of intertree areas in open woodlands of South Morocco. . 2021; 2021 ():1-26.

Chicago/Turabian Style

Mario Kirchhoff; Tobias Romes; Irene Marzolff; Manuel Seeger; Ali Aït Hssaine; Johannes B. Ries. 2021. "Spatial patterns of argan-tree influence on soil quality of intertree areas in open woodlands of South Morocco." 2021, no. : 1-26.

Preprint content
Published: 03 March 2021
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The endemic argan tree (Argania spinosa) in Morocco, which is the source of the valuable argan oil, forms open-canopy forests that are highly degraded due to overgrazing, illegal cutting of firewood and the expanding intensive agriculture. Because of the high grazing pressure young sprouts cannot establish themselves, reforestation measures are often unsuccessful and the bare areas between the isolated trees are expanding. In a previous study, we could already show that these intertree areas are more degraded than the areas under the trees, regarding various soil parameters as well as their erodibility and infiltration capacity.

The spatial extent of argan trees on soil quality from the trunk to the intertree area is so far unknown. Hypothetically, the tree influences the soil of the intertree area by wind drift of tree litter and soil material towards the East, i.e. main wind direction, and downhill by runoff and erosion processes of soil material downslope. Tree shadow in the hot midday and afternoon sun should have positive influences on soil moisture in northern or northeastern directions. To test this hypothesis, we took 424 soil samples around 31 argan trees in four directions, uphill, downhill and in both directions parallel to the slope towards the nearest neighbouring tree in that direction. Samples along these transects were taken near the trunk, just inside and just outside the area covered by the tree crown and in the intertree area in the middle between two trees. The soil samples were analysed for various soil parameters (C/N, percolation stability, electrical conductivity, pH, soil moisture).

The first results show that the influence of the trees is not limited to the crown-covered area but for some trees extends further into the intertree area in specific directions according to the hypothesis (East due to wind drift, North due to shade and downslope due to slope runoff). For other trees the influence of the trees does not even encompass the whole crown-covered area, where we found similarly lower soil quality as for the bare intertree areas. These differences may result from the degradation state of the tree as well as from the different characteristics of the study areas. Understanding the way argan trees influence their surrounding intertree areas would enable structured reforestation measures with a higher chance of successful rejuvenation of the argan forest.

ACS Style

Mario Kirchhoff; Tobias Romes; Irene Marzolff; Manuel Seeger; Ali Aït Hssaine; Johannes B. Ries. Spatial patterns of argan-tree influence on soil quality of intertree areas in open woodlands in South Morocco. 2021, 1 .

AMA Style

Mario Kirchhoff, Tobias Romes, Irene Marzolff, Manuel Seeger, Ali Aït Hssaine, Johannes B. Ries. Spatial patterns of argan-tree influence on soil quality of intertree areas in open woodlands in South Morocco. . 2021; ():1.

Chicago/Turabian Style

Mario Kirchhoff; Tobias Romes; Irene Marzolff; Manuel Seeger; Ali Aït Hssaine; Johannes B. Ries. 2021. "Spatial patterns of argan-tree influence on soil quality of intertree areas in open woodlands in South Morocco." , no. : 1.

Preprint content
Published: 03 March 2021
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In semi-arid to arid South-west Morocco, the once ubiquitous endemic argan tree (Argania spinosa) forms the basis of a traditional silvo-pastoral agroforestry system with complex usage rights involving pasturing and tree-browsing by goats, sheep and camels, smallholder agriculture and oil production. Widespread clearing of the open-canopy argan forests has been undertaken in the 12th–17th century for sugarcane production, and again in the 20th century for fuelwood extraction and conversion to commercial agriculture. The remaining argan woodlands have continued to decline due to firewood extraction, charcoal-making, overgrazing and overbrowsing. Soil and vegetation are increasingly being degraded; natural rejuvenation is hindered, and soil-erosion rates rise due to reduced infiltration and increased runoff. Numerous studies indicate that tree density and canopy cover have been generally decreasing for the last 200 years. However, there is little quantitative and spatially explicit information about these forest-cover dynamics.

In our study, the tree-cover change between 1967 and 2019 was analysed for 30 test sites of 1 ha each in argan woodlands of different degradation stages in the provinces of Taroudant, Agadir Ida-Outanane and Chtouka-Aït Baha. We used historical black-and-white satellite photography from the American reconnaissance programme CORONA, recent high-resolution multispectral imagery from the commercial WorldView satellites and ultrahigh resolution small-format aerial photography taken with an unmanned aerial system (UAS) to map the presence, absence and comparative crown-size class of 2610 trees in 1967 and 2019. We supplemented the remotely-sensed data with field observations on tree structure and architecture.

Results show that plant densities reach up to 300 argan trees and shrubs per hectare, and the mean tree density has increased from 58 trees/ha in 1967 to 86 trees/ha in 2019. While 7% of the 1967 trees have vanished today, more than one third of today’s trees could not be observed in 1967. This positive change has a high uncertainty, however, as most of the increase concerns small trees (< 3 m diameter) which might have been missed on the lower-resolution CORONA images.

When combined with our field data on tree architecture, tree count – albeit a parameter easily attained by remote sensing – is revealed as too simple an indicator for argan-forest dynamics, and the first impression of a positive development needs to be revised: The new small trees as well as trees with decreased crown sizes clearly show much stronger degradation characteristics than others, indicating increased pressures on the argan ecosystem during recent decades. Structural traits of the smaller trees also suggest that the apparent increase of tree count is not a result of natural rejuvenation, but mostly of stump re-sprouting, often into multi-stemmed trees, after felling of a tree. The density of the argan forest in the 1960s, prior to the general availability of cooking gas in the region and before the stronger enforcement of the argan logging ban following the declaration of the UNESCO biosphere reserve, may have marked a historic low in our study area, making the baseline of our change analysis far removed from the potential natural state of the argan ecosystem.

ACS Style

Irene Marzolff; Mario Kirchhoff; Robin Stephan; Manuel Seeger; Ali Aït Hssaïne; Johannes B. Ries. Degradation or recovery of argan woodlands in South Morocco? Tree count from satellite imagery between 1967–2019 may underestimate pressures on dryland forests status. 2021, 1 .

AMA Style

Irene Marzolff, Mario Kirchhoff, Robin Stephan, Manuel Seeger, Ali Aït Hssaïne, Johannes B. Ries. Degradation or recovery of argan woodlands in South Morocco? Tree count from satellite imagery between 1967–2019 may underestimate pressures on dryland forests status. . 2021; ():1.

Chicago/Turabian Style

Irene Marzolff; Mario Kirchhoff; Robin Stephan; Manuel Seeger; Ali Aït Hssaïne; Johannes B. Ries. 2021. "Degradation or recovery of argan woodlands in South Morocco? Tree count from satellite imagery between 1967–2019 may underestimate pressures on dryland forests status." , no. : 1.

Research article
Published: 13 September 2020 in Earth Surface Processes and Landforms
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The endemic argan woodlands cover large parts of South Morocco and create a characteristic landscape with areas of sparsely vegetated and bare soil surfaces between the single trees. This unique ecosystem has been under extensive agrosilvopastoral management for centuries and is now at risk of degradation caused by overgrazing and increasing scarcity and variability of rainfall. To investigate susceptibility to wind erosion, we conducted an experimental‐empirical study including wind tunnel tests and a drone generated digital elevation model and quantified wind erodible material on five different associated surface types by means of sediment catchers. The highest emission flux was measured on freshly ploughed surfaces (1875 g m‐2 h‐1), while older ploughed areas with a re‐established crust produced a much lower emission flux (795 g m‐2 h‐1). Extensive tillage may have been a sustainable practice for generations, but increasing drought and uncertainty of rainfall now leads to an acute risk of severe soil erosion and dust production. The typical crusted surfaces characterised by residual rock fragment accumulation and wash processes produced the second highest emission flux (1354 g m‐2 h‐1). Collected material from tree‐shaded areas (933 g m‐2 h‐1) was revealed as a considerable source of organic material possibly affecting substrate conditions positively on a larger regional scale. Lowest flux was measured on rock fragment covered surfaces (301 g m‐2 h‐1). The data show that open argan woodland may be a considerable source for wind erosion and dust production, depending on surface characteristics strongly related to management. An adapted management must include the conservation of the argan trees to offer a promising approach to prevent severe wind erosion and dust production and mitigate possible impacts of land‐use change and climate‐change related shifts in wind and rainfall patterns.

ACS Style

Miriam Marzen; Mario Kirchhoff; Irene Marzolff; Ali Aït Hssaine; Johannes B. Ries. Relative quantification of wind erosion in argan woodlands in the Souss Basin, Morocco. Earth Surface Processes and Landforms 2020, 45, 3808 -3823.

AMA Style

Miriam Marzen, Mario Kirchhoff, Irene Marzolff, Ali Aït Hssaine, Johannes B. Ries. Relative quantification of wind erosion in argan woodlands in the Souss Basin, Morocco. Earth Surface Processes and Landforms. 2020; 45 (15):3808-3823.

Chicago/Turabian Style

Miriam Marzen; Mario Kirchhoff; Irene Marzolff; Ali Aït Hssaine; Johannes B. Ries. 2020. "Relative quantification of wind erosion in argan woodlands in the Souss Basin, Morocco." Earth Surface Processes and Landforms 45, no. 15: 3808-3823.

Preprint content
Published: 17 July 2020
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Non-forest ecosystems, dominated by shrubs, grasses and herbaceous plants, provide ecosystem services including carbon sequestration and forage for grazing, yet are highly sensitive to climatic changes. Yet these ecosystems are poorly represented in remotely-sensed biomass products and are undersampled by in-situ monitoring. Current global change threats emphasise the need for new tools to capture biomass change in non-forest ecosystems at appropriate scales. Here we assess whether canopy height inferred from drone photogrammetry allows the estimation of aboveground biomass (AGB) across low-stature plant species sampled through a global site network. We found mean canopy height is strongly predictive of AGB across species, demonstrating standardised photogrammetric approaches are generalisable across growth forms and environmental settings. Biomass per-unit-of-height was similar within, but different among, plant functional types. We find drone-based photogrammetry allows for monitoring of AGB across large spatial extents and can advance understanding of understudied and vulnerable non-forested ecosystems across the globe.

ACS Style

Andrew M Cunliffe; Karen Anderson; Fabio Boschetti; Richard E Brazier; Hugh A Graham; Isla H Myers-Smith; Thomas Astor; Matthias M Boer; Leonor Calvo; Patrick E Clark; Michael D Cramer; Miguel S. Encinas-Lara; Stephen M Escarzaga; Jose M Fernandez-Guisuraga; Adrian G Fisher; Katerina Gdulov; Breahna M Gillespie; Anne Griebel; Niall P Hanan; Muhammad S Hanggito; Stefan Haselberger; Caroline A Havrilla; Philip Heilman; Wenjie Ji; Jason W Karl; Mario Kirchhoff; Sabine Kraushaar; Mitchell B Lyons; Irene Marzolff; Marguerite E Mauritz; Cameron D McIntire; Daniel Metzen; Luis A Mendez-Barroso; Simon C Power; Jiri Prosek; Enoc Sanz-Ablanedo; Katherine J Sauer; Damian Schulze-Bruninghoff; Petra Simov; Stephen Sitch; Julian L Smit; Caiti M Steele; Susana Suarez-Seoane; Sergio A Vargas; Miguel L Villarreal; Fleur Visser; Michael Wachendorf; Hannes Wirnsberger; Robert Wojcikiewicz. Drone-derived canopy height predicts biomass across non-forest ecosystems globally. 2020, 1 .

AMA Style

Andrew M Cunliffe, Karen Anderson, Fabio Boschetti, Richard E Brazier, Hugh A Graham, Isla H Myers-Smith, Thomas Astor, Matthias M Boer, Leonor Calvo, Patrick E Clark, Michael D Cramer, Miguel S. Encinas-Lara, Stephen M Escarzaga, Jose M Fernandez-Guisuraga, Adrian G Fisher, Katerina Gdulov, Breahna M Gillespie, Anne Griebel, Niall P Hanan, Muhammad S Hanggito, Stefan Haselberger, Caroline A Havrilla, Philip Heilman, Wenjie Ji, Jason W Karl, Mario Kirchhoff, Sabine Kraushaar, Mitchell B Lyons, Irene Marzolff, Marguerite E Mauritz, Cameron D McIntire, Daniel Metzen, Luis A Mendez-Barroso, Simon C Power, Jiri Prosek, Enoc Sanz-Ablanedo, Katherine J Sauer, Damian Schulze-Bruninghoff, Petra Simov, Stephen Sitch, Julian L Smit, Caiti M Steele, Susana Suarez-Seoane, Sergio A Vargas, Miguel L Villarreal, Fleur Visser, Michael Wachendorf, Hannes Wirnsberger, Robert Wojcikiewicz. Drone-derived canopy height predicts biomass across non-forest ecosystems globally. . 2020; ():1.

Chicago/Turabian Style

Andrew M Cunliffe; Karen Anderson; Fabio Boschetti; Richard E Brazier; Hugh A Graham; Isla H Myers-Smith; Thomas Astor; Matthias M Boer; Leonor Calvo; Patrick E Clark; Michael D Cramer; Miguel S. Encinas-Lara; Stephen M Escarzaga; Jose M Fernandez-Guisuraga; Adrian G Fisher; Katerina Gdulov; Breahna M Gillespie; Anne Griebel; Niall P Hanan; Muhammad S Hanggito; Stefan Haselberger; Caroline A Havrilla; Philip Heilman; Wenjie Ji; Jason W Karl; Mario Kirchhoff; Sabine Kraushaar; Mitchell B Lyons; Irene Marzolff; Marguerite E Mauritz; Cameron D McIntire; Daniel Metzen; Luis A Mendez-Barroso; Simon C Power; Jiri Prosek; Enoc Sanz-Ablanedo; Katherine J Sauer; Damian Schulze-Bruninghoff; Petra Simov; Stephen Sitch; Julian L Smit; Caiti M Steele; Susana Suarez-Seoane; Sergio A Vargas; Miguel L Villarreal; Fleur Visser; Michael Wachendorf; Hannes Wirnsberger; Robert Wojcikiewicz. 2020. "Drone-derived canopy height predicts biomass across non-forest ecosystems globally." , no. : 1.

Preprint content
Published: 23 March 2020
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In semi-arid to arid South-west Morocco, the endemic argan tree (Argania spinosa) forms open woodlands that are the basis of a traditional agroforestry system involving rain-fed agriculture, pasturing of goats, sheep and camels, and oil production. Due to the high grazing pressure, the trees show various morphological traits and growth forms that are strongly related to browsing intensity. The overall appearance of Argania spinosa ranges from trees with a large, round crown and single trunk, over multi-stem, umbrella-shaped and hourglass-shaped trees to heavily condensed cone-shaped cushions.

30 test sites of 1 ha each in argan woodlands of different degradation stages were surveyed with an unmanned aerial vehicle (UAV) and RGB optical camera using a dedicated flight scheme for capturing full 3D tree shape at approx. 1 cm resolution. Structure-from-Motion (SfM)-photogrammetric processing yielded dense 3D point clouds as well as ultra-high resolution (1.5 cm) digital surface models (DSMs), terrain models (DTMs), crown-height models (CHMs) and orthophoto mosaics. Tree height and crown size were extracted from the CHMs, and 3D point-cloud characteristics (point density, profile shape/layer structure) and canopy structures were analysed within a geographical information system (GIS). Using field-based reference data on tree architecture and browsing features of 2494 trees, we were able to assign characteristic combinations of the GIS-derived structural parameters to three browsing-intensity classes and thus classify each argan tree via the architectural shape captured in its UAV-based 3D point cloud. We found that the majority of argan trees at the study sites are characterised by high browsing intensities. The small percentage of trees in the minimum browsing class are mostly inaccessible to grazing livestock. We conclude that UAV-based remote sensing has a high potential for mapping structural indicators of tree degradation by herbivore browsing in open woodland environments.

ACS Style

Irene Marzolff; Robin Stephan; Mario Kirchhoff; Manuel Seeger; Ali Aït Hssaïne; Johannes B. Ries. UAV-based classification of tree-browsing intensity in open woodlands. 2020, 1 .

AMA Style

Irene Marzolff, Robin Stephan, Mario Kirchhoff, Manuel Seeger, Ali Aït Hssaïne, Johannes B. Ries. UAV-based classification of tree-browsing intensity in open woodlands. . 2020; ():1.

Chicago/Turabian Style

Irene Marzolff; Robin Stephan; Mario Kirchhoff; Manuel Seeger; Ali Aït Hssaïne; Johannes B. Ries. 2020. "UAV-based classification of tree-browsing intensity in open woodlands." , no. : 1.

Preprint content
Published: 23 March 2020
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The argan tree (Argania spinosa) populations, endemic to South Morocco, have been highly degraded. Although the argan tree is the source of the valuable argan oil and is protected by law, overbrowsing and -grazing as well as the intensification and expansion of agricultural land lead to tree and soil degradation. Young stands cannot establish themselves; undergrowth is scarce due to the semiarid/arid climate and thus, goats, sheep and dromedaries continually browse the trees. Canopy-covered areas decrease and are degraded while areas without vegetation cover between the argan trees increase.

On 30 test sites, 60 soil samples of tree and intertree areas were studied on their soil physical and chemical properties. 36 rainfall simulations and 60 single-ring infiltration measurements were conducted to measure potential differences between tree/intertree areas in their runoff/erosion and infiltration properties. Significant differences using a t-test were found for the studied parameters saturated hydraulic conductivity, pH, electric conductivity, percolation stability, total C-content, total N-content, K-content, Na-content and Mg-content. Surface runoff and soil erosion were not statistically significant, but showed similar trends due to the higher complexity of runoff formation. The soil covered by argan trees generally showed less signs of degradation than intertree areas. With ever-expanding intertree areas due to the lack of rejuvenation of argan trees a further degradation of the soil can be assumed.

ACS Style

Mario Kirchhoff; Lars Engelmann; Lutz Leroy Zimmermann; Irene Marzolff; Manuel Seeger; Ali Aït Hssaine; Johannes B. Ries. Soil Degradation in Argan Woodlands, South Morocco. 2020, 1 .

AMA Style

Mario Kirchhoff, Lars Engelmann, Lutz Leroy Zimmermann, Irene Marzolff, Manuel Seeger, Ali Aït Hssaine, Johannes B. Ries. Soil Degradation in Argan Woodlands, South Morocco. . 2020; ():1.

Chicago/Turabian Style

Mario Kirchhoff; Lars Engelmann; Lutz Leroy Zimmermann; Irene Marzolff; Manuel Seeger; Ali Aït Hssaine; Johannes B. Ries. 2020. "Soil Degradation in Argan Woodlands, South Morocco." , no. : 1.

Journal article
Published: 22 October 2019 in Water
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The endemic argan tree (Argania spinosa) populations in South Morocco are highly degraded due to their use as a biomass resource in dry years and illegal firewood extraction. The intensification and expansion of agricultural land lead to a retreat of the wooded area, while the remaining argan open woodlands are often overgrazed. Thus, canopy-covered areas decrease while areas without vegetation cover between the argan trees increase. In total, 36 rainfall simulation experiments as well as 60 infiltration measurements were conducted to investigate the potential difference between tree-covered areas and bare intertree areas. In addition, 60 soil samples were taken under the trees and in the intertree areas parallel to the contour lines. Significant differences using a t-test were found between tree and intertree areas for the studied parameters Ksat, Kh, pH, electric conductivity, percolation stability, total C-content, total N-content, K-content, Na-content, and Mg-content. Surface runoff and soil losses were not as conclusive but showed similar trends. The results showed that argan trees influence the soil underneath significantly, while the soil in intertree areas is less protected and more degraded. It is therefore reasonable to assume further degradation of the soil when intertree areas extend further due to lack of rejuvenation of argan trees.

ACS Style

Mario Kirchhoff; Lars Engelmann; Lutz Leroy Zimmermann; Manuel Seeger; Irene Marzolff; Ali Aït Hssaine; Johannes B. Ries. Geomorphodynamics in Argan Woodlands, South Morocco. Water 2019, 11, 2193 .

AMA Style

Mario Kirchhoff, Lars Engelmann, Lutz Leroy Zimmermann, Manuel Seeger, Irene Marzolff, Ali Aït Hssaine, Johannes B. Ries. Geomorphodynamics in Argan Woodlands, South Morocco. Water. 2019; 11 (10):2193.

Chicago/Turabian Style

Mario Kirchhoff; Lars Engelmann; Lutz Leroy Zimmermann; Manuel Seeger; Irene Marzolff; Ali Aït Hssaine; Johannes B. Ries. 2019. "Geomorphodynamics in Argan Woodlands, South Morocco." Water 11, no. 10: 2193.

Book
Published: 01 January 2019 in Small-Format Aerial Photography and UAS Imagery
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ACS Style

James S. Aber; Irene Marzolff; Johannes B. Ries; Susan E.W. Aber. Small-Format Aerial Photography and UAS Imagery. Small-Format Aerial Photography and UAS Imagery 2019, 1 .

AMA Style

James S. Aber, Irene Marzolff, Johannes B. Ries, Susan E.W. Aber. Small-Format Aerial Photography and UAS Imagery. Small-Format Aerial Photography and UAS Imagery. 2019; ():1.

Chicago/Turabian Style

James S. Aber; Irene Marzolff; Johannes B. Ries; Susan E.W. Aber. 2019. "Small-Format Aerial Photography and UAS Imagery." Small-Format Aerial Photography and UAS Imagery , no. : 1.

Article
Published: 17 November 2017 in Earth Surface Processes and Landforms
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Gully and badland erosion constitute important land-degradation processes with severe on-site and off-site effects above all in sedimentary deposits and alluvial soils of the arid and semi-arid regions. Agricultural use of the affected land is impeded both by the irreversible loss of topsoil and the morphological dissection of the terrain. In various badland regions around the world, a solution to the latter problem is attempted by infilling of gullies and levelling of badland topography in order restore a morphology suitable for agricultural cultivation. Gully and badland levelling for agricultural reclamation has been conducted for decades in the large ravine lands of India. This study aims at analysing the distribution and dynamics of land levelling within the Chambal badlands in Morena district, Madhya Pradesh, between 1971 and 2015. Using high to medium resolution satellite images from the Corona, Landsat, Aster and RapidEye missions and a multi-temporal classification approach, we have mapped and quantified areas that were newly levelled within eight observation periods. We analysed the spatial relation of levelled land to several physical and socio-economic factors that potentially influence the choice of reclamation site by employing geographic information system (GIS) analysis methods and results from focus-group discussions in selected villages. Results show that nearly 38 km2 or 23% of the badlands in the study area have been levelled within 45 years. The levelling rate generally increases during the observation period, but the annual variability is high. We have found spatial relationships to badland morphology, vicinity of existing cropland and proximity to villages and drainage lines. From a socio-economic point of view, availability of financial and technical means, access rights to the badland and ownership issues play an important role. Considering studies on soil degradation caused by levelling of badlands in other regions, the sustainability of the newly reclaimed fields in the Chambal badlands is questionable. Copyright © 2017 John Wiley & Sons, Ltd.

ACS Style

Irene Marzolff; Padmini Pani. Dynamics and patterns of land levelling for agricultural reclamation of erosional badlands in Chambal Valley (Madhya Pradesh, India). Earth Surface Processes and Landforms 2017, 43, 524 -542.

AMA Style

Irene Marzolff, Padmini Pani. Dynamics and patterns of land levelling for agricultural reclamation of erosional badlands in Chambal Valley (Madhya Pradesh, India). Earth Surface Processes and Landforms. 2017; 43 (2):524-542.

Chicago/Turabian Style

Irene Marzolff; Padmini Pani. 2017. "Dynamics and patterns of land levelling for agricultural reclamation of erosional badlands in Chambal Valley (Madhya Pradesh, India)." Earth Surface Processes and Landforms 43, no. 2: 524-542.

Journal article
Published: 30 June 2017 in Cuadernos de Investigación Geográfica
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Geomorphological relief units are related to certain processes and the history of their development. They are well defined by form and material. This study investigates erosion processes on different relief units. Rainfall simulations, rill experiments and monitoring by aerial photography were performed on dunes, glacis, Holocene fillings, talus material and Quaternary loam terraces in order to analyse the varying process intensities. Splash, interrill erosion and runoff generation were quantified by rainfall simulation experiments, rill erosion by rill experiments and gully growth by monitoring over several years. The test sites are situated in NE- and SE-Spain, S-Morocco and N-Burkina Faso. The results clearly show that the measured processes are very different from those supposed to be relevant for the formation of relief units. Dunes and Holocene fillings are highly erodible by splash and interrill erosion. In contrast, Quaternary loam terraces show a low susceptibility to erosion processes. We conclude that the relief units show very different dominances of erosion processes and process intensities. The differentiation is more significant with increasing scale and complexity of the erosion process: The extent of gully growth varies much more between the different units than those of splash and interrill erosion do.

ACS Style

T. Iserloh; S. Wirtz; M. Seeger; I. Marzolff; J.B. Ries. Erosion processes on different relief units: the relationship of form and process. Cuadernos de Investigación Geográfica 2017, 43, 171 .

AMA Style

T. Iserloh, S. Wirtz, M. Seeger, I. Marzolff, J.B. Ries. Erosion processes on different relief units: the relationship of form and process. Cuadernos de Investigación Geográfica. 2017; 43 (1):171.

Chicago/Turabian Style

T. Iserloh; S. Wirtz; M. Seeger; I. Marzolff; J.B. Ries. 2017. "Erosion processes on different relief units: the relationship of form and process." Cuadernos de Investigación Geográfica 43, no. 1: 171.

Journal article
Published: 06 June 2016 in Geographicalia
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El pastoreo extensivo de campos en barbecho o abandonados entre la Depresión Central del Ebro y el Pirineo Central impide la regeneración de la cubierta vegetal. Se desarrolla un patrón típico de areas con geomorfodinárnica muy activa en los senderos del ganado, junto a otras extensas superficies estables. En el Prepirineo y el Pirineo Central, se puede incluso observar la reducción de la cubierta de matorral ya existente, de forma simultánea al incremento de la geomorfodinámica. Las zonas afectadas por fuerte erosión lineal aumentan a lo largo de los senderos, ya que éstos muestran tasas de escorrentia superficial y de erosión muy altas. A causa de estos efectos, los incentivos comunitarios a la ganadería ovina han de ser revisados de forma crítica.

ACS Style

J. B. Ries; M. Seeger; I. Marzolff. Influencia del pastoreo en la cubierta vegetal y la geomorfodinámica en el transecto Depresión del Ebro-Pirineos. Geographicalia 2016, 5 .

AMA Style

J. B. Ries, M. Seeger, I. Marzolff. Influencia del pastoreo en la cubierta vegetal y la geomorfodinámica en el transecto Depresión del Ebro-Pirineos. Geographicalia. 2016; (45):5.

Chicago/Turabian Style

J. B. Ries; M. Seeger; I. Marzolff. 2016. "Influencia del pastoreo en la cubierta vegetal y la geomorfodinámica en el transecto Depresión del Ebro-Pirineos." Geographicalia , no. 45: 5.

Journal article
Published: 02 September 2014 in Remote Sensing
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This study aims at the detection of gully-affected areas by applying object-based image analysis in the region of Taroudannt, Morocco, which is highly affected by gully erosion while simultaneously representing a major region of agro-industry with a high demand of arable land. As high-resolution optical satellite data are readily available from various sensors and with a much better temporal resolution than 3D terrain data, an area-wide mapping approach to extract gully-affected areas using only optical satellite imagery was developed. The methodology additionally incorporates expert knowledge and freely-available vector data in a cyclic object-based image analysis approach. This connects the two fields of geomorphology and remote sensing. The classification results show the successful implementation of the developed approach and allow conclusions on the current distribution of gullies. The results of the classification were checked against manually delineated reference data incorporating expert knowledge based on several field campaigns in the area, resulting in an overall classification accuracy of 62%. The error of omission accounts for 38% and the error of commission for 16%, respectively. Additionally, a manual assessment was carried out to assess the quality of the applied classification algorithm. The limited error of omission contributes with 23% to the overall error of omission and the limited error of commission contributes with 98% to the overall error of commission. This assessment improves the results and confirms the high quality of the developed approach for area-wide mapping of gully-affected areas in larger regions. In the field of landform mapping, the overall quality of the classification results is often assessed with more than one method to incorporate all aspects adequately.

ACS Style

Sebastian D'Oleire-Oltmanns; Irene Marzolff; Dirk Tiede; Thomas Blaschke. Detection of Gully-Affected Areas by Applying Object-Based Image Analysis (OBIA) in the Region of Taroudannt, Morocco. Remote Sensing 2014, 6, 8287 -8309.

AMA Style

Sebastian D'Oleire-Oltmanns, Irene Marzolff, Dirk Tiede, Thomas Blaschke. Detection of Gully-Affected Areas by Applying Object-Based Image Analysis (OBIA) in the Region of Taroudannt, Morocco. Remote Sensing. 2014; 6 (9):8287-8309.

Chicago/Turabian Style

Sebastian D'Oleire-Oltmanns; Irene Marzolff; Dirk Tiede; Thomas Blaschke. 2014. "Detection of Gully-Affected Areas by Applying Object-Based Image Analysis (OBIA) in the Region of Taroudannt, Morocco." Remote Sensing 6, no. 9: 8287-8309.

Journal article
Published: 01 February 2014 in CATENA
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Klaus Daniel Peter; Sebastian D'Oleire-Oltmanns; Johannes B. Ries; Irene Marzolff; Ali Ait Hssaine. Soil erosion in gully catchments affected by land-levelling measures in the Souss Basin, Morocco, analysed by rainfall simulation and UAV remote sensing data. CATENA 2014, 113, 24 -40.

AMA Style

Klaus Daniel Peter, Sebastian D'Oleire-Oltmanns, Johannes B. Ries, Irene Marzolff, Ali Ait Hssaine. Soil erosion in gully catchments affected by land-levelling measures in the Souss Basin, Morocco, analysed by rainfall simulation and UAV remote sensing data. CATENA. 2014; 113 ():24-40.

Chicago/Turabian Style

Klaus Daniel Peter; Sebastian D'Oleire-Oltmanns; Johannes B. Ries; Irene Marzolff; Ali Ait Hssaine. 2014. "Soil erosion in gully catchments affected by land-levelling measures in the Souss Basin, Morocco, analysed by rainfall simulation and UAV remote sensing data." CATENA 113, no. : 24-40.

Research article
Published: 21 November 2012 in Evidence-Based Complementary and Alternative Medicine
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The study of acupuncture-related sensations, likedeqiand propagated sensations along channels (PSCs), has a long tradition in acupuncture basic research. The phenomenon itself, however, remains poorly understood. To study the connection between PSC and classical meridians, we applied a geographic information system (GIS) to analyze sketches of acupuncture sensations from healthy volunteers after laser acupuncture. As PSC can be subtle, we aimed at reducing the confounding impact of external stimuli by carrying out the experiment in a floatation tank under restricted environmental stimulation. 82.4% of the subjects experienced PSC, that is, they had line-like or 2-dimensional sensations, although there were some doubts that these were related to the laser stimulation. Line-like sensations on the same limb were averaged to calculate sensation mean courses, which were then compared to classical meridians by measuring the mean distance between the two. Distances ranged from 0.83 cm in the case of the heart (HT) and spleen (SP) meridian to 6.27 cm in the case of the kidney (KI) meridian. Furthermore, PSC was observed to “jump” between adjacent meridians. In summary, GIS has proven to be a valuable tool to study PSC, and our results suggest a close connection between PSC and classical meridians.

ACS Style

Florian Beissner; Irene Marzolff. Investigation of Acupuncture Sensation Patterns under Sensory Deprivation Using a Geographic Information System. Evidence-Based Complementary and Alternative Medicine 2012, 2012, 1 -10.

AMA Style

Florian Beissner, Irene Marzolff. Investigation of Acupuncture Sensation Patterns under Sensory Deprivation Using a Geographic Information System. Evidence-Based Complementary and Alternative Medicine. 2012; 2012 ():1-10.

Chicago/Turabian Style

Florian Beissner; Irene Marzolff. 2012. "Investigation of Acupuncture Sensation Patterns under Sensory Deprivation Using a Geographic Information System." Evidence-Based Complementary and Alternative Medicine 2012, no. : 1-10.

Journal article
Published: 07 November 2012 in Remote Sensing
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This article presents an environmental remote sensing application using a UAV that is specifically aimed at reducing the data gap between field scale and satellite scale in soil erosion monitoring in Morocco. A fixed-wing aircraft type Sirius I (MAVinci, Germany) equipped with a digital system camera (Panasonic) is employed. UAV surveys are conducted over different study sites with varying extents and flying heights in order to provide both very high resolution site-specific data and lower-resolution overviews, thus fully exploiting the large potential of the chosen UAV for multi-scale mapping purposes. Depending on the scale and area coverage, two different approaches for georeferencing are used, based on high-precision GCPs or the UAV’s log file with exterior orientation values respectively. The photogrammetric image processing enables the creation of Digital Terrain Models (DTMs) and ortho-image mosaics with very high resolution on a sub-decimetre level. The created data products were used for quantifying gully and badland erosion in 2D and 3D as well as for the analysis of the surrounding areas and landscape development for larger extents.

ACS Style

Sebastian D'Oleire-Oltmanns; Irene Marzolff; Klaus Daniel Peter; Johannes B. Ries. Unmanned Aerial Vehicle (UAV) for Monitoring Soil Erosion in Morocco. Remote Sensing 2012, 4, 3390 -3416.

AMA Style

Sebastian D'Oleire-Oltmanns, Irene Marzolff, Klaus Daniel Peter, Johannes B. Ries. Unmanned Aerial Vehicle (UAV) for Monitoring Soil Erosion in Morocco. Remote Sensing. 2012; 4 (11):3390-3416.

Chicago/Turabian Style

Sebastian D'Oleire-Oltmanns; Irene Marzolff; Klaus Daniel Peter; Johannes B. Ries. 2012. "Unmanned Aerial Vehicle (UAV) for Monitoring Soil Erosion in Morocco." Remote Sensing 4, no. 11: 3390-3416.

Journal article
Published: 18 July 2011 in Earth Surface Processes and Landforms
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This study investigates how medium‐term gully‐development data differ from short‐term data, and which factors influence their spatial and temporal variability at nine selected actively retreating bank gullies situated in four Spanish basin landscapes. Small‐format aerial photographs using unmanned, remote‐controlled platforms were taken at the gully sites in short‐term intervals of one to two years over medium‐term periods of seven to 13 years and gully change during each period was determined using stereophotogrammetry and a geographic information system. Results show a high variability of annual gully retreat rates both between gullies and between observation periods. The mean linear headcut retreat rates range between 0·02 and 0·26 m a–1. Gully area loss was between 0·8 and 22 m² a–1 and gully volume loss between 0·5 to 100 m³ a–1, of which sidewall erosion may play a considerable part. A non‐linear relationship between catchment area and medium‐term gully headcut volume change was found for these gullies. The short‐term changes observed at the individual gullies show very high variability: on average, the maximum headcut volume change observed in 7–13 years was 14·3 times larger than the minimum change. Dependency on precipitation varies but is clearly higher for headcuts than sidewalls, especially in smaller and less disturbed catchments. The varying influences of land use and human activities with their positive or negative effects on runoff production and connectivity play a dominant role in these study areas, both for short‐term variability and medium‐term difference in gully development. The study proves the value of capturing spatially continuous, high‐resolution three‐dimensional data using small‐format aerial photography for detailed gully monitoring. Results confirm that short‐term data are not representative of longer‐term gully development and demonstrate the necessity for medium‐ to long‐term monitoring. However, short‐term data are still required to understand the processes – particularly human activity at varying time scales – causing fluctuations in gully erosion rates. Copyright © 2011 John Wiley & Sons, Ltd.

ACS Style

Irene Marzolff; Johannes B. Ries; Jean Poesen. Short-term versus medium-term monitoring for detecting gully-erosion variability in a Mediterranean environment. Earth Surface Processes and Landforms 2011, 36, 1604 -1623.

AMA Style

Irene Marzolff, Johannes B. Ries, Jean Poesen. Short-term versus medium-term monitoring for detecting gully-erosion variability in a Mediterranean environment. Earth Surface Processes and Landforms. 2011; 36 (12):1604-1623.

Chicago/Turabian Style

Irene Marzolff; Johannes B. Ries; Jean Poesen. 2011. "Short-term versus medium-term monitoring for detecting gully-erosion variability in a Mediterranean environment." Earth Surface Processes and Landforms 36, no. 12: 1604-1623.

Journal article
Published: 30 April 2011 in Cuadernos de Investigación Geográfica
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ACS Style

I. Marzolff; J. B. Ries. Piping as a process of gully erosion in small-format aerial pothography : A short note. Cuadernos de Investigación Geográfica 2011, 37, 115 .

AMA Style

I. Marzolff, J. B. Ries. Piping as a process of gully erosion in small-format aerial pothography : A short note. Cuadernos de Investigación Geográfica. 2011; 37 (1):115.

Chicago/Turabian Style

I. Marzolff; J. B. Ries. 2011. "Piping as a process of gully erosion in small-format aerial pothography : A short note." Cuadernos de Investigación Geográfica 37, no. 1: 115.

Journal article
Published: 01 December 2009 in Zeitschrift für Geomorphologie
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ACS Style

Manuel Seeger; Irene Marzolff; Johannes B. Ries. Identification of gully-development processes in semi-arid NE-Spain. Zeitschrift für Geomorphologie 2009, 53, 417 -431.

AMA Style

Manuel Seeger, Irene Marzolff, Johannes B. Ries. Identification of gully-development processes in semi-arid NE-Spain. Zeitschrift für Geomorphologie. 2009; 53 (4):417-431.

Chicago/Turabian Style

Manuel Seeger; Irene Marzolff; Johannes B. Ries. 2009. "Identification of gully-development processes in semi-arid NE-Spain." Zeitschrift für Geomorphologie 53, no. 4: 417-431.