Items 21-40 of 565

    • Journal Article

      Reconciling Canopy Interception Parameterization and Rainfall Forcing Frequency in the Community Land Model for Simulating Evapotranspiration of Rainforests and Oil Palm Plantations in Indonesia 

      Fan, Yuanchao; Meijide, Ana; Lawrence, David M.; Roupsard, Olivier; Carlson, Kimberly M.; Chen, Hsin‐Yi; Röll, Alexander; Niu, Furong; Knohl, Alexander
      Journal of Advances in Modeling Earth Systems 2019; 11(3) p.732-751
      By mediating evapotranspiration processes, plant canopies play an important role in the terrestrial water cycle and regional climate. Substantial uncertainties exist in modeling canopy water interception and related hydrological processes due to rainfall forcing frequency selection and varying canopy traits. Here we design a new time interpolation method “zero” to better represent convective‐type precipitation in tropical regions. We also implement and recalibrate plant functional type‐specific interception parameters for rainforests and oil palm plantations, where oil palms express higher water interception capacity than forests, using the Community Land Model (CLM) versions 4.5 and 5.0 with CLM‐Palm embedded. Reconciling the interception scheme with realistic precipitation forcing produces more accurate canopy evaporation and transpiration for both plant functional types, which in turn improves simulated evapotranspiration and energy partitioning when benchmarked against observations from our study sites in Indonesia and an extensive literature review. Regional simulations for Sumatra and Kalimantan show that industrial oil palm plantations have 18–27% higher transpiration and 15–20% higher evapotranspiration than forests on an annual regional average basis across different ages or successional stages, even though the forests experience higher average precipitation according to reanalysis data. Our land‐only modeling results indicate that current oil palm plantations in Sumatra and Kalimantan use 15–20% more water (mean 220 mm or 20 Gt) per year compared to lowland rainforests of the same extent. The extra water use by oil palm reduces soil moisture and runoff that could affect ecosystem services such as productivity of staple crops and availability of drinking water in rural areas.
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    • Journal Article

      Agroforestry creates carbon sinks whilst enhancing the environment in agricultural landscapes in Europe 

      Kay, Sonja; Rega, Carlo; Moreno, Gerardo; den Herder, Michael; Palma, João H.N.; Borek, Robert; Crous-Duran, Josep; Freese, Dirk; Giannitsopoulos, Michail; Graves, Anil; et al.
      Jäger, MareikeLamersdorf, NorbertMemedemin, DaniyarMosquera-Losada, RosaPantera, AnastasiaParacchini, Maria LuisaParis, PierluigiRoces-Díaz, José V.Rolo, VictorRosati, AdolfoSandor, MignonSmith, JoSzerencsits, ErichVarga, AnnaViaud, ValérieWawer, RafalBurgess, Paul J.Herzog, Felix
      Land Use Policy 2019; 83 p.581-593
      Agroforestry, relative to conventional agriculture, contributes significantly to carbon sequestration, increases a range of regulating ecosystem services, and enhances biodiversity. Using a transdisciplinary approach, we combined scientific and technical knowledge to evaluate nine environmental pressures in terms of ecosystem services in European farmland and assessed the carbon storage potential of suitable agroforestry systems, proposed by regional experts. First, regions with potential environmental pressures were identified with respect to soil health (soil erosion by water and wind, low soil organic carbon), water quality (water pollution by nitrates, salinization by irrigation), areas affected by climate change (rising temperature), and by underprovision in biodiversity (pollination and pest control pressures, loss of soil biodiversity). The maps were overlaid to identify areas where several pressures accumulate. In total, 94.4% of farmlands suffer from at least one environmental pressure, pastures being less affected than arable lands. Regional hotspots were located in north-western France, Denmark, Central Spain, north and south-western Italy, Greece, and eastern Romania. The 10% of the area with the highest number of accumulated pressures were defined as Priority Areas, where the implementation of agroforestry could be particularly effective. In a second step, European agroforestry experts were asked to propose agroforestry practices suitable for the Priority Areas they were familiar with, and identified 64 different systems covering a wide range of practices. These ranged from hedgerows on field boundaries to fast growing coppices or scattered single tree systems. Third, for each proposed system, the carbon storage potential was assessed based on data from the literature and the results were scaled-up to the Priority Areas. As expected, given the wide range of agroforestry practices identified, the carbon sequestration potentials ranged between 0.09 and 7.29 t C ha−1 a−1. Implementing agroforestry on the Priority Areas could lead to a sequestration of 2.1 to 63.9 million t C a−1 (7.78 and 234.85 million t CO2eq a−1) depending on the type of agroforestry. This corresponds to between 1.4 and 43.4% of European agricultural greenhouse gas (GHG) emissions. Moreover, promoting agroforestry in the Priority Areas would contribute to mitigate the environmental pressures identified there. We conclude that the strategic and spatially targeted establishment of agroforestry systems could provide an effective means of meeting EU policy objectives on GHG emissions whilst providing a range of other important benefits.
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    • Journal Article

      Seeking consensus in German forest conservation: An analysis of contemporary concepts 

      Demant, Laura; Meyer, Peter; Sennhenn-Reulen, Holger; Walentowski, Helge; Bergmeier, Erwin; Demant, Laura; Meyer, Peter; Sennhenn-Reulen, Holger; Walentowski, Helge; Bergmeier, Erwin
      Nature Conservation 2019; 35 p.1-23
      Setting operational conservation objectives is a major challenge for effective biodiversity conservation worldwide. To analyse forest conservation objectives in Germany in a transparent manner and to achieve a consistent and consensual framework, we systematically classified conservation objectives suggested in concepts by different stakeholders. We analysed 79 biodiversity and forest conservation concepts of different stakeholder groups at various scales and applied textual content analysis and Dirichlet regression to reach a high degree of transferability and applicability. Our analysis revealed a broad consensus concerning forest conservation across stakeholders and scales, albeit with slight differences in focus, but we detected a scale-related mismatch. A wide array of conservation objectives covered social, biotic and abiotic natural resources. Conservation of species, ecosystems and structural elements in forests were found to be of primary importance across stakeholders and scale levels. Shortcomings in the conservation concepts were found in addressing genetic diversity, abiotic resources and socio-cultural objectives. Our results show that problems in forest conservation may be rooted in trade-offs between aims, targeting mismatch across scale levels and insufficient implementation of objectives.
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    • Journal Article

      Mobile genetic elements explain size variation in the mitochondrial genomes of four closely-related Armillaria species 

      Kolesnikova, Anna I.; Putintseva, Yuliya A.; Simonov, Evgeniy P.; Biriukov, Vladislav V.; Oreshkova, Natalya V.; Pavlov, Igor N.; Sharov, Vadim V.; Kuzmin, Dmitry A.; Anderson, James B.; Krutovsky, Konstantin V.
      BMC Genomics. 2019 May 08;20(1):351
      Background Species in the genus Armillaria (fungi, basidiomycota) are well-known as saprophytes and pathogens on plants. Many of them cause white-rot root disease in diverse woody plants worldwide. Mitochondrial genomes (mitogenomes) are widely used in evolutionary and population studies, but despite the importance and wide distribution of Armillaria, the complete mitogenomes have not previously been reported for this genus. Meanwhile, the well-supported phylogeny of Armillaria species provides an excellent framework in which to study variation in mitogenomes and how they have evolved over time. Results Here we completely sequenced, assembled, and annotated the circular mitogenomes of four species: A. borealis, A. gallica, A. sinapina, and A. solidipes (116,443, 98,896, 103,563, and 122,167 bp, respectively). The variation in mitogenome size can be explained by variable numbers of mobile genetic elements, introns, and plasmid-related sequences. Most Armillaria introns contained open reading frames (ORFs) that are related to homing endonucleases of the LAGLIDADG and GIY-YIG families. Insertions of mobile elements were also evident as fragments of plasmid-related sequences in Armillaria mitogenomes. We also found several truncated gene duplications in all four mitogenomes. Conclusions Our study showed that fungal mitogenomes have a high degree of variation in size, gene content, and genomic organization even among closely related species of Armillara. We suggest that mobile genetic elements invading introns and intergenic sequences in the Armillaria mitogenomes have played a significant role in shaping their genome structure. The mitogenome changes we describe here are consistent with widely accepted phylogenetic relationships among the four species.
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    • Journal Article

      The Role of Low Soil Temperature for Photosynthesis and Stomatal Conductance of Three Graminoids From Different Elevations 

      Göbel, Leonie; Coners, Heinz; Hertel, Dietrich; Willinghöfer, Sandra; Leuschner, Christoph
      Frontiers in Plant Science 2019; 10: Art. 330
      In high-elevation grasslands, plants can encounter periods with high air temperature while the soil remains cold, which may lead to a temporary mismatch in the physiological activity of leaves and roots. In a climate chamber experiment with graminoid species from three elevations (4400, 2400, and 250 m a.s.l.), we tested the hypothesis that soil temperature can influence photosynthesis and stomatal conductance independently of air temperature. Soil monoliths with swards of Kobresia pygmaea (high alpine), Nardus stricta (lower alpine), and Deschampsia flexuosa (upper lowland) were exposed to soil temperatures of 25, 15, 5, and -2°C and air temperatures of 20 and 10°C for examining the effect of independent soil and air temperature variation on photosynthesis, leaf dark respiration, and stomatal conductance and transpiration. Soil frost (-2°C) had a strong negative effect on gas exchange and stomatal conductance in all three species, independent of the elevation of origin. Leaf dark respiration was stimulated by soil frost in D. flexuosa, but not in K. pygmaea, which also had a lower temperature optimum of photosynthesis. Soil cooling from 15 to 5°C did not significantly reduce stomatal conductance and gas exchange in any of the species. We conclude that all three graminoids are able to maintain a relatively high root water uptake in cold, non-frozen soil, but the high-alpine K. pygmaea seems to be especially well adapted to warm shoot - cold root episodes, as it has a higher photosynthetic activity at 10 than 20°C air temperature and does not up-regulate leaf dark respiration upon soil freezing, as was observed in the grasses from warmer climates.
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    • Journal Article

      Drone-Based Assessment of Canopy Cover for Analyzing Tree Mortality in an Oil Palm Agroforest 

      Khokthong, Watit; Zemp, Delphine Clara; Irawan, Bambang; Sundawati, Leti; Kreft, Holger; Hölscher, Dirk
      Frontiers in Forests and Global Change 2019; 2: Art. 12
      Oil palm monocultures are highly productive, but there are widespread negative impacts on biodiversity and ecosystem functions. Some of these negative impacts might be mitigated by mixed-species tree interplanting to create agroforestry systems, but there is little experience with the performance of trees planted in oil palm plantations. We studied a biodiversity enrichment experiment in the lowlands of Sumatra that was established in a 6- to 12-year-old oil palm plantation by planting six tree species in different mixtures on 48 plots. Three years after tree planting, canopy cover was assessed by drone-based photogrammetry using the structure-from-motion technique. Drone-derived canopy cover estimates were highly correlated with traditional ground-based hemispherical photography along the equality line, indicating the usefulness and comparability of the approach. Canopy cover was further partitioned between oil palm and tree canopies. Thinning of oil palms before tree planting created a more open and heterogeneous canopy cover. Oil palm canopy cover was then extracted at the level of oil palms and individual trees and combined with ground-based mortality assessment for all 3,819 planted trees. For three tree species (Archidendron pauciflorum, Durio zibethinus, and Shorea leprosula), the probability of mortality during the year of the study was dependent on the amount of oil palm canopy cover. We regard the drone-based method for deriving and partitioning spatially explicit information as a promising way for many questions addressing canopy cover in ecological applications and the management of agroforestry systems.
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    • Journal Article

      Can Traditional Authority Improve the Governance of Forestland and Sustainability? Case Study from the Congo (DRC) 

      Majambu, Eliezer; Mampeta Wabasa, Salomon; Welepele Elatre, Camille; Boutinot, Laurence; Ongolo, Symphorien
      Land 2019; 8(5): Art. 74
      With about 107 million hectares of moist forest, the Democratic Republic of Congo (DRC) is a perfect paradox of a natural resources endowed country caught in repeated economic and socio-political crises. Democratic Republic of Congo possesses about 60% of the Congo basin’s forest on which the majority of its people rely for their survival. Even if the national forest land in the countryside is mainly exploited by local populations based on customary rights, they usually do not have land titles due to the fact that the state claims an exclusive ownership of all forest lands in the Congo basin including in DRC. The tragedy of “bad governance” of natural resources is often highlighted in the literature as one of the major drivers of poverty and conflicts in DRC. In the forest domain, several studies have demonstrated that state bureaucracies cannot convincingly improve the governance of forestland because of cronyism, institutional weaknesses, corruption and other vested interests that govern forest and land tenure systems in the country. There are however very few rigorous studies on the role of traditional leaders or chiefdoms in the governance of forests and land issues in the Congo basin. This research aimed at addressing this lack of knowledge by providing empirical evidence through the case study of Yawalo village, located around the Yangambi Biosphere Reserve in the Democratic Republic of Congo. From a methodological perspective, it used a mixed approach combining both qualitative (field observations, participatory mapping, interviews, focal group discussions, and desk research,) and quantitative (remote sensing and statistics) methods. The main findings of our research reveal that: (i) vested interests of traditional rulers in the DRC countryside are not always compatible with a sustainable management of forestland; and (ii) influential users of forestland resources at the local level take advantage of traditional leaders’ weaknesses—lack of autonomy and coercive means, erratic recognition of customary rights, and poor legitimacy—to impose illegal hunting and uncontrolled forest exploitation.
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    • Journal Article

      …Fell Upas Sits, the Hydra-Tree of Death †, or the Phytotoxicity of Trees 

      Lebedev, Vadim G.; Krutovsky, Konstantin V.; Shestibratov, Konstantin A.
      Molecules 2019; 24(8): Art. 1636
      The use of natural products that can serve as natural herbicides and insecticides is a promising direction because of their greater safety for humans and environment. Secondary metabolites of plants that are toxic to plants and insects-allelochemicals-can be used as such products. Woody plants can produce allelochemicals, but they are studied much less than herbaceous species. Meanwhile, there is a problem of interaction of woody species with neighboring plants in the process of introduction or invasion, co-cultivation with agricultural crops (agroforestry) or in plantation forestry (multiclonal or multispecies plantations). This review describes woody plants with the greatest allelopathic potential, allelochemicals derived from them, and the prospects for their use as biopesticides. In addition, the achievement of and the prospects for the use of biotechnology methods in relation to the allelopathy of woody plants are presented and discussed.
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    • Journal Article

      Multiple plant diversity components drive consumer communities across ecosystems 

      Schuldt, Andreas; Ebeling, Anne; Kunz, Matthias; Staab, Michael; Guimarães-Steinicke, Claudia; Bachmann, Dörte; Buchmann, Nina; Durka, Walter; Fichtner, Andreas; Fornoff, Felix; et al.
      Härdtle, WernerHertzog, Lionel R.Klein, Alexandra-MariaRoscher, ChristianeSchaller, Jörgvon Oheimb, GoddertWeigelt, AlexandraWeisser, WolfgangWirth, ChristianZhang, JiayongBruelheide, HelgeEisenhauer, Nico
      Nature Communications 2019; 10(1): Art. 1460
      Humans modify ecosystems and biodiversity worldwide, with negative consequences for ecosystem functioning. Promoting plant diversity is increasingly suggested as a mitigation strategy. However, our mechanistic understanding of how plant diversity affects the diversity of heterotrophic consumer communities remains limited. Here, we disentangle the relative importance of key components of plant diversity as drivers of herbivore, predator, and parasitoid species richness in experimental forests and grasslands. We find that plant species richness effects on consumer species richness are consistently positive and mediated by elevated structural and functional diversity of the plant communities. The importance of these diversity components differs across trophic levels and ecosystems, cautioning against ignoring the fundamental ecological complexity of biodiversity effects. Importantly, plant diversity effects on higher trophic-level species richness are in many cases mediated by modifications of consumer abundances. In light of recently reported drastic declines in insect abundances, our study identifies important pathways connecting plant diversity and consumer diversity across ecosystems.
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    • Journal Article

      New R-Based Methodology to Optimize the Identification of Root Endophytes against Heterobasidion parviporum. 

      Rigerte, Linda; Blumenstein, Kathrin; Terhonen, Eeva
      Microorganisms 2019; 7(4): Art. 102
      Many root fungal endophytes inhabiting forest trees have potential impact on the health and disease progression of certain tree species. Hence, the screening of root endophytes for their biocontrol abilities is relevant for their potential to protect their hosts against invaders. The aim of this research is to screen for the potential inhibitory effects of selected conifer root endophytes during interaction, in vitro, with the root rot pathogen, Heterobasidion parviporum. Here, we introduce a guideline that facilitates the use of root fungal endophytes as biocontrol agents. We isolated fungal root endophytes from eight different conifers. These root fungal endophytes were evaluated for their antagonism against the root rot pathogen, H. parviporum, by means of paired-culture antagonism assays. We determined the antagonism of the isolated root fungal endophytes to elucidate potential biocontrol applications. For the analysis, a software package in R was developed. Endophyte candidates with antagonistic potential were identified.
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    • Journal Article

      Optimizing State Forest Institutions for Forest People: A Case Study on Social Sustainability from Tunisia 

      Hasnaoui, Ameni; Krott, Max
      Sustainability 2019; 11(7): Art. 1954
      In Tunisia the livelihoods of nearly 750,000 “forest people” strongly depend on state forests. State forest institutions that manage more than 90% of forests have a special responsibility for the social sustainability of these people’s situation. Thus, it is important to evaluate the performance of these institutions, as such evaluations represent an option to help formulate sustainable development strategies for forest people. This study evaluates the performance of state forest institutions in regard to forest people based on a comprehensive three-layer model. The data were collected in 2016 and 2017 from documents, observations and interviews. The results partly supported the first hypothesis that “state forest institutions employ different market, non-market and political instruments to influence the use and the protection of forests”, with an exception for market instruments. The second hypothesis stating that “the outcomes of these instruments for forest people differ from those for the general forest sector” was supported by empirical evidence. The evaluation revealed practices in Tunisia that provide a basis for organizational reforms supporting forest people. Adapted technologies that fit the traditional know-how of forest people and a better representation are required. Furthermore, the strengthening of state forest institutions against the influence of foreign donors would contribute to elaborating a development strategy for forest people.
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    • Journal Article

      Landscape-Scale Mixtures of Tree Species are More Effective than Stand-Scale Mixtures for Biodiversity of Vascular Plants, Bryophytes and Lichens 

      Heinrichs, Steffi; Ammer, Christian; Mund, Martina; Boch, Steffen; Budde, Sabine; Fischer, Markus; Müller, Jörg; Schöning, Ingo; Schulze, Ernst-Detlef; Schmidt, Wolfgang; et al.
      Weckesser, MartinSchall, Peter
      Forests 2019; 10(1): Art. 73
      Tree species diversity can positively affect the multifunctionality of forests. This is why conifer monocultures of Scots pine and Norway spruce, widely promoted in Central Europe since the 18th and 19th century, are currently converted into mixed stands with naturally dominant European beech. Biodiversity is expected to benefit from these mixtures compared to pure conifer stands due to increased abiotic and biotic resource heterogeneity. Evidence for this assumption is, however, largely lacking. Here, we investigated the diversity of vascular plants, bryophytes and lichens at the plot (alpha diversity) and at the landscape (gamma diversity) level in pure and mixed stands of European beech and conifer species (Scots pine, Norway spruce, Douglas fir) in four regions in Germany. We aimed to identify compositions of pure and mixed stands in a hypothetical forest landscape that can optimize gamma diversity of vascular plants, bryophytes and lichens within regions. Results show that gamma diversity of the investigated groups is highest when a landscape comprises different pure stands rather than tree species mixtures at the stand scale. Species mainly associated with conifers rely on light regimes that are only provided in pure conifer forests, whereas mixtures of beech and conifers are more similar to beech stands. Combining pure beech and pure conifer stands at the landscape scale can increase landscape level biodiversity and conserve species assemblages of both stand types, while landscapes solely composed of stand scale tree species mixtures could lead to a biodiversity reduction of a combination of investigated groups of 7 up to 20%.
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    • Journal Article

      Multiple forest attributes underpin the supply of multiple ecosystem services 

      Felipe-Lucia, María R.; Soliveres, Santiago; Penone, Caterina; Manning, Peter; van der Plas, Fons; Boch, Steffen; Prati, Daniel; Ammer, Christian; Schall, Peter; Gossner, Martin M.; et al.
      Bauhus, JürgenBuscot, FrancoisBlaser, StefanBlüthgen, Nicode Frutos, AngelEhbrecht, MartinFrank, KevinGoldmann, KeziaHänsel, FalkJung, KirstenKahl, TiemoNauss, ThomasOelmann, YvonnePena, RodicaPolle, AndreaRenner, SwenSchloter, MichaelSchöning, IngoSchrumpf, MarionSchulze, Ernst-DetlefSolly, EmilySorkau, ElisabethStempfhuber, BarbaraTschapka, MarcoWeisser, Wolfgang W.Wubet, TesfayeFischer, MarkusAllan, Eric
      Nature Communications 2018; 9(1): Art. 4839
      Trade-offs and synergies in the supply of forest ecosystem services are common but the drivers of these relationships are poorly understood. To guide management that seeks to promote multiple services, we investigated the relationships between 12 stand-level forest attributes, including structure, composition, heterogeneity and plant diversity, plus 4 environmental factors, and proxies for 14 ecosystem services in 150 temperate forest plots. Our results show that forest attributes are the best predictors of most ecosystem services and are also good predictors of several synergies and trade-offs between services. Environmental factors also play an important role, mostly in combination with forest attributes. Our study suggests that managing forests to increase structural heterogeneity, maintain large trees, and canopy gaps would promote the supply of multiple ecosystem services. These results highlight the potential for forest management to encourage multifunctional forests and suggest that a coordinated landscape-scale strategy could help to mitigate trade-offs in human-dominated landscapes.
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    • Journal Article

      Rocks rock: the importance of rock formations as resting sites of the Eurasian lynx Lynx lynx 

      Signer, Johannes; Filla, Marc; Schoneberg, Sebastian; Kneib, Thomas; Bufka, Ludek; Belotti, Elisa; Heurich, Marco
      Wildlife Biology 2019; 2019(1)
      Eurasian lynx Lynx lynx L. are recolonizing parts of their former range in Europe. Not only are lynx strictly protected as a species, but also their habitat and in particular their resting sites are protected. As the known characteristics of lynx resting sites are restricted to vegetation structure, it is difficult to take resting sites into account in planning processes. Here, we show the importance of rock formations for potential resting sites selection and analyzed the frequencies at which GPS-collared lynx returned to potential resting sites in the Bohemian Forest Ecosystem at the border between the Czech Republic and Germany. Lynx showed a strong selection for proximity of rocks for resting site selection, and the distance of potential resting sites to rocks was an important predictor for determining whether lynx return to the resting site or not. Furthermore, the frequency of returns to the resting site was positively influenced by the distance to roads and geomorphology. Our findings highlight the importance of rock formations as resting sites for lynx, which can help with the implementation of concrete protection measures.
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    • Journal Article

      Decrease of the surface pH of maple and the production of nitrate by three pulsed dielectric barrier discharges 

      Peters, F.; Gelker, M.; Fleckenstein, M.; Militz, H.; Ohms, G.; Viöl, W.
      Wood Science and Technology 2018; 52(6) p.1495-1510
      In this study, the influence of dielectric barrier discharges at atmospheric pressure on maple sapwood was analyzed. Three common discharge types, a coplanar surface barrier discharge (CSBD), a direct dielectric barrier discharge and a jet discharge/ remote plasma, were realized by the same electrodes and power supply. In general, plasma treatments are known to modify various surface properties leading to improved adhesion. For resins such as urea formaldehyde, the curing behavior is dependent on the pH. Therefore, the change of the surface pH value of maple is measured. As the main product of plasma-generated nitrogen oxides, the nitrate concentrations and consequently the nitric acid concentrations of the surfaces were determined. A significant pH reduction from about pH 5.6 to pH 4.6 was reached after a 30 s plasma treatment. An increase in the nitrate concentration over the plasma treatment duration was measured for all three discharges with a maximum of 6.6 mg/L for the CSBD, which corresponds to a concentration of 8.25 mg per m2 wooden surface.
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    • Journal Article

      Moisture behavior of weathered wood surfaces during cyclic wetting: measurements and modeling 

      Niklewski, J.; Brischke, C.; Frühwald Hansson, E.; Meyer-Veltrup, L.
      Wood Science and Technology 2018; 52(6) p.1431-1450
      The effects of weathering on the in-service moisture behavior of wood have received only limited attention so far, with much focus being on the effect of photodegradation on the hydrophobicity of the wood surface. The objective of the present study was to examine the effect of weathering surfaces on the overall moisture behavior of wood specimens exposed to short-term cyclic spraying, with special emphasis on the surface conditions involved. Specimens cut from eight different species including hardwoods and softwoods were weathered for 8 years and continuously monitored during a single-sided cyclic spraying together with a set of axially matched controls. After each spray cycle, the duration of surface wetness was evaluated by resistance moisture sensors as well as an optical approach (colorimetric) based on time-lapse images. The moisture content in the core was monitored simultaneously by use of resistance moisture sensors. The optical method correlated well with the electrical resistance measurements and provided a simple and practical measure of the areal distribution of the surface wetness. The results showed specimens with a weathered surface to sustain a wet surface for about twice the duration of their axially matched control. A considerable, albeit smaller, effect was also observed deeper in the core. By adapting the length of the wet period on the exposed boundary, the corresponding response at the core of the Norway spruce specimens was reproduced numerically.
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    • Journal Article

      Modeling Forest Woody Biomass Availability for Energy Use Based on Short-Term Forecasting Scenarios 

      Flores Hernández, Ulises; Jaeger, Dirk; Samperio, Jorge Islas
      Waste and Biomass Valorization
      Bioenergy in Mexico offers a great potential as a transition strategy for introducing new energy supply chains. However, studies which focus on wood supply chains for bioenergy generation at a national level are scarce. Hence, this paper presents a model for predicting short-term availability of woody biomass for energetic use according to two scenarios. Scenario A exhibits business as usual conditions. In scenario B, the availability of forest woody biomass is improved by an increment in the areas of sustainably managed forest. The theoretical, technical and economic potentials of forest woody biomass availability for energetic use were assessed using (a) numerical modeling, (b) Holt-Winters exponential smoothing and (c) regression analyses Sustainability constraints and challenges such as soil degradation, terrain slope and mechanization level were considered. A regional case study was carried out, focusing on three species with the highest utilization rates (Pinus, Quercus and Abies). Setting the base at the year 2013, a forecast analysis for the year 2023 was performed. Under scenario B, for year 2023 a technical potential of 60.22 PJ was calculated, meaning an achievement of the goals set by the National Forestry Council regarding hectares under sustainable utilization. Furthermore, a net future value analysis was carried out to account the economic output during the forecasted period. Where comprehensive data was not available, the developed model was especially useful for predicting potentially available woody biomass for energy use.
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    • Journal Article

      Measuring Livelihood Diversification and Forest Conservation Choices: Insights from Rural Cameroon 

      Kimengsi, Jude; Pretzsch, Jürgen; Kechia, Mukong; Ongolo, Symphorien
      Forests 2019; 10(2): Art. 81
      While forests’ contribution to rural livelihoods has been unearthed scientifically, the patterns, determinants and forest conservation policy implications of livelihood diversification still beg for more scientific and policy edification. This paper makes a contribution in this regard, using household data (N = 200) from eight villages around the Kilum-Ijim Forest Landscape of Cameroon. The ordinary least square and the logit model are used to explore the determinants of livelihood diversification and the likelihood of forest dependence, respectively. The diversification patterns were analysed using a simple t-test, and the multinomial logit for conservation choices. We find that forest-related activities are a source of livelihood diversification for 63% of households, with non-timber forest products (NTFP) domestication (31%) and medicinal plant extraction (30%) being the most preferred. For non-forest activities, migration is the most preferred diversification strategy. Generally, households with favourable socio-economic status prefer non-forest to forest activities for livelihood diversification. The regression estimates indicate that older respondents are more likely to depend on the forest than the young, whereas males and individuals with at least some secondary education are less likely than their respective counterparts to rely on the forest. The results also suggest those who participated in training, educated household heads and older individuals are significantly more likely to choose high-valued diversification strategies. Concerning conservation activities, households with favourable socio-economic status are on average less likely to adopt NTFP domestication and more likely to adopt bee-keeping as a conservation choice. The results suggest the need for policy considerations to: (i) effectively integrate women in forest management processes, (ii) intensify trainings for conservation-friendly diversification approaches, (iii) regulate unclean energy use and (iv) encourage value chain improvement for conservation-friendly products.
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    • Journal Article

      Optimal leaf water status regulation of plants in drylands 

      Ratzmann, Gregor; Zakharova, Liubov; Tietjen, Britta
      Scientific Reports 2019; 9(1): Art. 3768
      Leaf water potential regulation is a key process in whole plant and ecosystem functioning. While low water potentials induced by open stomata may initially be associated with greater CO2 supply and a higher water flux from the rhizosphere to the canopy, they also inhibit cell growth, photosynthesis and ultimately water supply. Here, we show that plants regulate their leaf water potential in an optimal manner under given constraints using a simple leaf water status regulation model and data from a global dryland leaf water potential database. Model predictions agree strongly with observations across locations and species and are further supported by experimental data. Leaf water potentials non-linearly decline with soil water potential, underlining the shift from maximizing water supply to avoiding stress with declining water availability. Our results suggest that optimal regulation of the leaf water status under varying water supply and stress tolerance is a ubiquitous property of plants in drylands. The proposed model moreover provides a novel quantitative framework describing how plants respond to short- and long-term changes in water availability and may help elaborating models of plant and ecosystem functioning.
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    • Journal Article

      Intensive tropical land use massively shifts soil fungal communities 

      Brinkmann, Nicole; Schneider, Dominik; Sahner, Josephine; Ballauff, Johannes; Edy, Nur; Barus, Henry; Irawan, Bambang; Budi, Sri Wilarso; Qaim, Matin; Daniel, Rolf; et al.
      Polle, Andrea
      Scientific Reports 2019; 9(1) p.3403-3403
      Soil fungi are key players in nutrient cycles as decomposers, mutualists and pathogens, but the impact of tropical rain forest transformation into rubber or oil palm plantations on fungal community structures and their ecological functions are unknown. We hypothesized that increasing land use intensity and habitat loss due to the replacement of the hyperdiverse forest flora by nonendemic cash crops drives a drastic loss of diversity of soil fungal taxa and impairs the ecological soil functions. Unexpectedly, rain forest conversion was not associated with strong diversity loss but with massive shifts in soil fungal community composition. Fungal communities clustered according to land use system and loss of plant species. Network analysis revealed characteristic fungal genera significantly associated with different land use systems. Shifts in soil fungal community structure were particularly distinct among different trophic groups, with substantial decreases in symbiotrophic fungi and increases in saprotrophic and pathotrophic fungi in oil palm and rubber plantations in comparison with rain forests. In conclusion, conversion of rain forests and current land use systems restructure soil fungal communities towards enhanced pathogen pressure and, thus, threaten ecosystem health functions.
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