TY - JOUR A1 - Krause, Stuart A1 - Sanders, Tanja G. M. A1 - Mund, Jan-Peter A1 - Greve, Klaus T1 - UAV-Based Photogrammetric Tree Height Measurement for Intensive Forest Monitoring JF - Remote Sensing N2 - The measurement of tree height has long been an important tree attribute for the purpose of calculating tree growth, volume, and biomass, which in turn deliver important ecological and economical information to decision makers. Tree height has traditionally been measured by indirect field-based techniques, however these methods are rarely contested. With recent advances in Unmanned Aerial Vehicle (UAV) remote sensing technologies, the possibility to acquire accurate tree heights semi-automatically has become a reality. In this study, photogrammetric and field-based tree height measurements of a Scots Pine stand were validated using destructive methods. The intensive forest monitoring site implemented for the study was configured with permanent ground control points (GCPs) measured with a Total Station (TS). Field-based tree height measurements resulted in a similar level of error to that of the photogrammetric measurements, with root mean square error (RMSE) values of 0.304 m (1.82%) and 0.34 m (2.07%), respectively (n = 34). A conflicting bias was, however, discovered where field measurements tended to overestimate tree heights and photogrammetric measurements were underestimated. The photogrammetric tree height measurements of all trees (n = 285) were validated against the field-based measurements and resulted in a RMSE of 0.479 m (2.78%). Additionally, two separate photogrammetric tree height datasets were compared (n = 251), and a very low amount of error was observed with a RMSE of 0.138 m (0.79%), suggesting a high potential for repeatability. This study shows that UAV photogrammetric tree height measurements are a viable option for intensive forest monitoring plots and that the possibility to acquire within-season tree growth measurements merits further study. Additionally, it was shown that negative and positive biases evident in field-based and UAV-based photogrammetric tree height measurements could potentially lead to misinterpretation of results when field-based measurements are used as validation. KW - tree height KW - UAV KW - intensive forest monitoring KW - photogrammety KW - precision forestry Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-3240 SN - 2072-4292 IS - 11(7) PB - MDPI ER - TY - JOUR A1 - Ochoa, Jesus A1 - Sanyé-Mengual, Esther A1 - Specht, Kathrin A1 - Fernández, Juan A. A1 - Bañón, Sebastián A1 - Orsini, Francesco A1 - Magrefi, Francesca A1 - Bazzocchi, Giovanni A1 - Halder, Severin A1 - Martens, Dörte A1 - Kappel, Noemi A1 - Gianquinto, Giorgio T1 - Sustainable Community Gardens Require Social Engagement and Training: A Users’ Needs Analysis in Europe JF - Sustainability N2 - Urban gardens are spreading in many cities across Europe, with community gardening being a fundamental form of urban agriculture. While the literature reveals the essential role that community gardens can play in terms of learning and education, no studies have investigated the training needs for participants in community gardens to ensure their successful development. The goal of this article is to evaluate the training requirements of urban community gardens to ensure their successful implementation and their contribution to sustainability in European cities. Two questionnaires of users’ needs analysis were designed and implemented in Berlin, Bologna, Budapest, and Cartagena. The results unveiled the need to re-enforce the training in the formation and community building phases of community gardens towards ensuring the creation of an engaged gardening community to maintain activity, particularly for top-down activities (e.g., research-related gardens). Users claimed their need for being trained on crop management skills (e.g., maintenance, bed preparation, organic practices) and on communication skills to further disseminate their activity, thereby increasing the potential for citizen engagement. Such requirements could be overcome with the creation of urban gardens networks, where experiences and knowledge are shared among practitioners. Policy recommendations are provided based on the outputs of this study. KW - urban agriculture KW - community gardening KW - training KW - community building KW - urban planning KW - knowledge KW - lifelong learning Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-3261 SN - 2071-1050 IS - 11(14) PB - MDPI ER - TY - CHAP A1 - Munk, Christoph A1 - Clauder, Lothar A1 - Pfriem, Alexander T1 - Sound absorption coefficient of thermally modified and unmodified wood species measured in an impedance tube T2 - Northern European Network for Wood Science and Engineering (WSE) - 15th Annual Meeting 2019 N2 - Different parts of the guitar body are made of certain wood species, selected by their specific properties. The sound board, which is mainly made of spruce or cedar, transfers the vibration of the strings to the resonance body by means of the bridge. The sides and the back of the guitar rather reflect the sound of the acoustic vibrations and are predominantly made of tropical hardwoods like palisander, mahogany or ebony species. These species have limited availability and are listed on the CITES Annex I and II. To substitute tropical wood species, thermally modified European wood species with improved acoustic properties and dimensional stability may be used. Although the acoustic reflection of the sides and the back parts of a guitar body is an important property, there is not much knowledge about this reflection behaviour of wood. A few studies like the work of Hong (1989), Kang (2010) or Smardzewski et al. (2013) investigated the sound absorption properties of unmodified wood. Subsequently this study considers the sound absorption coefficients of unmodified and thermally modified European wood species in comparison to an unmodified tropical wood species. KW - TMT KW - sound absorption coefficient KW - impedance tube Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-2890 ER - TY - JOUR A1 - Vogel, Sebastian A1 - Gebbers, Robin A1 - Oertel, Marcel A1 - Kramer, Eckart T1 - Evaluating Soil-Borne Causes of Biomass Variability in Grassland by Remote and Proximal Sensing JF - Sensors N2 - On a grassland field with sandy soils in Northeast Germany (Brandenburg), vegetation indices from multi-spectral UAV-based remote sensing were used to predict grassland biomass productivity. These data were combined with soil pH value and apparent electrical conductivity (ECa) from on-the-go proximal sensing serving as indicators for soil-borne causes of grassland biomass variation. The field internal magnitude of spatial variability and hidden correlations between the variables of investigation were analyzed by means of geostatistics and boundary-line analysis to elucidate the influence of soil pH and ECa on the spatial distribution of biomass. Biomass and pH showed high spatial variability, which necessitates high resolution data acquisition of soil and plant properties. Moreover, boundary-line analysis showed grassland biomass maxima at pH values between 5.3 and 7.2 and ECa values between 3.5 and 17.5 mS m−1. After calibrating ECa to soil moisture, the ECa optimum was translated to a range of optimum soil moisture from 7% to 13%. This matches well with to the plant-available water content of the predominantly sandy soil as derived from its water retention curve. These results can be used in site-specific management decisions to improve grassland biomass productivity in low-yield regions of the field due to soil acidity or texture-related water scarcity. KW - apparent electrical conductivity (ECa) KW - pH KW - UAV KW - boundary-line KW - quantile regression KW - law of minimum Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-3294 SN - 1424-8220 VL - 19 IS - 20 PB - MDPI ER - TY - JOUR A1 - Halwani, Mosab A1 - Reckling, Moritz A1 - Schuler, Johannes A1 - Bloch, Ralf A1 - Bachinger, Johann T1 - Soybean in No-Till Cover-Crop Systems JF - Agronomy N2 - Introducing agro-ecological techniques such as no-tillage systems with cover crops in rotations with soybean (Glycine max (L.) Merr.) could provide more resilience to changing climatic conditions and, at the same time, reduce soil erosion, nitrate leaching, and weed density in the main crop. However, there are challenges in introducing no-tillage techniques in crop systems in Europe as there is little quantitative knowledge about the agro-economic impact. The objectives of this study were to evaluate the agronomic and economic impacts of three soybean cropping systems involving a rye (Secale cereal L.) cover crop prior to soybean, i.e., two no-tillage systems; either herbicide-free with crimping the rye or herbicide-based without rye crimping and one plough-based in which rye was cut as green silage. The impacts of these cropping strategies were compared in a three-year cropping system experiment at a research station in north-eastern Germany with and without irrigation. The following parameters were measured: (1) cover crop biomass; (2) weed biomass; (3) soybean plant density; (4) soybean grain yield; and (5) gross margin of the cropping system. The results showed that all three soybean cropping systems can effectively suppress weeds. System (C), the no-tillage herbicide-based system, produced the lowest rye biomass and highest soybean yield; system (B), the no-tillage herbicide-free/crimped rye system, produced the highest rye biomass and lowest soybean yield compared to system (A), the standard cutting/plough-based system. The differences in rye biomass and soybean yield observed between the three systems could be mainly attributed to the timing of the cover crop termination and the soybean sowing date. The gross margin was highest in system (C), due to the high soybean grain yield. The low soybean grain yield in system (B) resulted in lower revenues and gross margins compared to systems (A) and (C), although system (B) could be economically attractive in organic farming with higher prices for organic soybean. In the particularly dry year 2016, gross margins were higher when soybean was irrigated compared to the rainfed cultivation, due to significantly higher grain yields. Before recommending the application of the no-tillage with cover crop technique for the conditions tested in north-eastern Germany, more investigations on the benefits and risks of this technique are needed. Further research needs to focus on maintaining a high rye biomass as well as on ensuring an early soybean planting date. Optimizing the crimping and drilling equipment is still required in order to develop good management practices for no-tillage herbicide-free systems in European conditions. KW - no-tillage KW - cover crop KW - irrigation KW - weed suppression KW - gross margin Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-3314 SN - 2073-4395 VL - 9 IS - 12 PB - MDPI ER - TY - JOUR A1 - Jha, Srijna A1 - Kächele, Harald A1 - Sieber, Stefan T1 - Factors Influencing the Adoption of Water Conservation Technologies by Smallholder Farmer Households in Tanzania JF - Water N2 - In Tanzania, the increasing population coupled with climate change amplifies issues of food insecurity and negatively impacts the livelihoods of smallholder farmer households. To address these issues a range of water conservation techniques (WCTs) have been useful. However, the adoption of these WCTs in Tanzania has been limited due to many reasons. With the objective to better understand and identify the factors that significantly influence the adoption of WCTs in Tanzania, the study uses survey data from 701 smallholder farmer households and a bivariate logistic regression, to provide, for the first time, a comprehensive model for the adoption of WCTs in Tanzania that includes a range of individual, household, socio-economic, and farmer perception related variables (factors). The evaluation shows that 120 farmers (17.12%) adopted WCTs and finds the farmer perceptions of rainfall instability, household wealth, and food security to be crucial. The results suggest that policy interventions should encourage conservation behavior (especially when the rainfall is perceived to be uncertain), emphasize the economic and food security-related benefits of adopting WCTs, include strategies that make adoption of WCTs attractive to female-led households, attempt to reach greater number of farmers via social networks and provide better access to public funds for farmers. KW - decision-making KW - logit regression KW - farmer perceptions KW - social networks KW - public funds KW - water conservation adoption Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-3320 SN - 2073-4441 VL - 11 IS - 12 PB - MDPI ER - TY - CHAP A1 - Schweiger, Julienne A1 - Schmidt, Henriette A1 - Aas, Gregor A1 - Gebauer, Gerhard A1 - Götz, Bernhard A1 - Hartmann, Holger A1 - Lenz, Claudia A1 - Pflugmacher, Candy A1 - Schmidt, Markus A1 - Schill, Harald T1 - Carbon isotopes elucidate drought stress in rare native tree species in NE-Germany Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-7627 N1 - Session 2: Stable isotopes in environmental research - bridging disciplines, organisms and processes, Poster 2.2, BayCEER Workshop 2019, October 10, 2019 - Campus University of Bayreuth, Germany ER - TY - CHAP A1 - Lenz, Claudia A1 - Lautner, Silke T1 - Trockenheitsgefährdung und Anpassung unterschiedlicher Fichtenpopulationen (Fichte-Trockenheit) Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-7641 N1 - Erste HNEE Nachhaltigkeitstage vom 20. bis 24. Mai 2019, Poster Präsentation von HNEE-Forschungsprojekten ER - TY - JOUR A1 - Thevs, Niels A1 - Gombert, Alina Joana A1 - Strenge, Eva A1 - Lleshi, Roland A1 - Aliev, Kumar A1 - Emileva, Begaiym T1 - Tree Wind Breaks in Central Asia and Their Effects on Agricultural Water Consumption JF - Land N2 - Across Central Asia, agriculture largely depends on irrigation due to arid and semi-arid climatic conditions. Water is abstracted from rivers, which are largely fed by glacier melt. In the course of climate change, glaciers melt down so that a reduced glacier volume and reduced water runoffs are expected to be available for irrigation. Tree wind breaks are one option to reduce water consumption in irrigated agriculture and build resilience against climate change. This paper therefore assesses the water consumption of major crops in Kyrgyzstan and adjacent areas, i.e., cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.), corn (Zea mays L.), rice (Oryza sativa L.), potato (Solanum tuberosum L.), and barley (Hordeum vulgare L.) in combination with tree wind breaks. Crop water consumption was assessed through the Penman Monteith approach. Tree wind break types investigated were single rows from poplars (Populus spec.) and multiple rows with understory vegetation by elm (Ulmus minor L.) and poplar, respectively. Tree water consumption was determined through sapflow measurements. The seasonal reference evapotranspiration (ETo) for field crops was 876–995 mm without wind breaks and dropped to less than half through multiple row wind breaks with understory vegetation (50 m spacing). Tree water consumption was 1125–1558 mm for poplar and 435 mm for elm. Among the wind break crop systems, elm wind breaks resulted in the highest reductions of water consumption, followed by single row poplars, at spacing of 50 and 100 m, respectively. However, elm grows much slower than poplar, so poplars might be more attractive for farmers. Furthermore, single row wind breaks might by much easier to be integrated into the agrarian landscape as they consume less space. KW - agroforestry KW - Populus KW - Ulmus KW - cotton KW - corn KW - microclimate KW - evapotranspiration KW - irrigation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-3306 SN - 2073-445X VL - 8 IS - 11 PB - MDPI ER -