Recent Submissions

  • Journal Article

    Response of Beech (Fagus sylvatica L.) Trees to Competition—New Insights from Using Fractal Analysis 

    Dorji; Annighöfer; Ammer; Seidel
    Remote Sensing 2019; 11(22)
    Individual tree architecture and the composition of tree species play a vital role for many ecosystem functions and services provided by a forest, such as timber value, habitat diversity, and ecosystem resilience. However, knowledge is limited when it comes to understanding how tree architecture changes in response to competition. Using 3D-laser scanning data from the German Biodiversity Exploratories, we investigated the detailed three-dimensional architecture of 24 beech (Fagus sylvatica L.) trees that grew under different levels of competition pressure. We created detailed quantitative structure models (QSMs) for all study trees to describe their branching architecture. Furthermore, structural complexity and architectural self-similarity were measured using the box-dimension approach from fractal analysis. Relating these measures to the strength of competition, the trees are exposed to reveal strong responses for a wide range of tree architectural measures indicating that competition strongly changes the branching architecture of trees. The strongest response to competition (rho = −0.78) was observed for a new measure introduced here, the intercept of the regression used to determine the box-dimension. This measure was discovered as an integrating descriptor of the size of the complexity-bearing part of the tree, namely the crown, and proven to be even more sensitive to competition than the box-dimension itself. Future studies may use fractal analysis to investigate and quantify the response of tree individuals to competition.
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  • Journal Article

    Response of Four Tree Species to Changing Climate in a Moisture-Limited Area of South Siberia 

    Babushkina, Elena A.; Zhirnova, Dina F.; Belokopytova, Liliana V.; Tychkov, Ivan I.; Vaganov, Eugene A.; Krutovsky, Konstantin V.
    Forests 2019; 10(11): Art. 999
    The response of vegetation to climate change is of special interest in regions where rapid warming is coupled with moisture deficit. This raises the question of the limits in plants’ acclimation ability and the consequent shifts of the vegetation cover. Radial growth dynamics and climatic response were studied in Scots pine (Pinus sylvestris L.), Siberian larch (Larix sibirica Ledeb.), and silver birch (Betula pendula Roth.) in the forest-steppe, and for Siberian elm (Ulmus pumila L.) in the steppe of South Siberia, as indicators of vegetation state and dynamics. Climate–growth relationships were analyzed by the following two approaches: (1) correlations between tree-ring width chronologies and short-term moving climatic series, and (2) optimization of the parameters of the Vaganov–Shashkin tree growth simulation model to assess the ecophysiological characteristics of species. Regional warming was accompanied by a slower increase of the average moisture deficit, but not in the severity of droughts. In the forest-steppe, the trees demonstrated stable growth and responded to the May–July climate. In the steppe, elm was limited by moisture deficit in May–beginning of June, during the peak water deficit. The forest-steppe stands were apparently acclimated successfully to the current climatic trends. It seems that elm was able to counter the water deficit, likely through its capacity to regulate transpiration by the stomatal morphology and xylem structure, using most of the stem as a water reservoir; earlier onset; and high growth rate, and these physiological traits may provide advantages to this species, leading to its expansion in steppes.
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  • Journal Article

    The Forest Policies of ASEAN and Montréal Process: Comparing Highly and Weakly Formalized Regional Regimes 

    Jeon, Sohui; Kumar Sarker, Pradip; Giessen, Lukas
    Forests 2019; 10(10): Art. 929
    Forests are governed by a combination of sub-national and national as well as global and regional regimes. Comparing the institutional variation of regional regimes, including their degrees of formalization, is gaining attention of studies on regionalism in International Relations. This study attempts to analyse the ways in which the selected cases of the forest-related Association of Southeast Asian Nations (ASEAN) and forest-focused Montréal Process (MP) regional regimes may have synergetic overlaps or disparity in their institutional design and forest policy development. For this, we combined IR’s ‘rational institutional design’ theory and a policy analysis approach. Using a qualitative data approach, we analyzed key structure-related historical regime documents (e.g., charters) issued since the inception of both regimes, and their latest forest policy initiatives for the periods 2016–2025 (Strategic Plan of Action for ASEAN Cooperation on Forestry) and 2009–2015 (Conceptual Framework for the Montréal Process Strategic Action Plan) with all relevant policy documents since the adoption of current policies. Based on that, we pose the empirical questions of how both regimes illustrate governance structure (i.e., institutional design), and on the other hand how to explain regime forest policies coherently and consistently in terms of their high versus low degree of formality. The results show that institutional design is highly explanatory based on treaty and non-treaty regime formation as well as forest-related/focused regime formation with the synergistic sustainable forest management (SFM) issue that embraces deforestation and forest degradation, biodiversity, timber certification, and greenhouse gas emission. Additionally, the results suggest that the policy goals adopted by both regimes are coherent and consistent based on the full set of policy elements. Concerning the remedy for fragmented global forest governance arrangements, both regimes would be an example of practicing SFM-focused policies with the incorporation of forest-related policy elements into a larger governance assemblage dealing with issues such as biodiversity conservation or climate change mitigation.
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  • Journal Article

    Drivers of the relative richness of naturalized and invasive plant species on Earth 

    Essl, Franz; Dawson, Wayne; Kreft, Holger; Pergl, Jan; Pyšek, Petr; Van Kleunen, Mark; Weigelt, Patrick; Mang, Thomas; Dullinger, Stefan; Lenzner, Bernd; et al.
    Moser, DietmarMaurel, NoëlieSeebens, HannoStein, AnkeWeber, EwaldChatelain, CyrilleInderjitGenovesi, PieroKartesz, JohnMorozova, OlgaNishino, MisakoNowak, Pauline MPagad, ShyamaShu, Wen-ShengWinter, Marten
    AoB PLANTS 2019; 11(5)
    Biological invasions are a defining feature of the Anthropocene, but the factors that determine the spatially uneven distribution of alien plant species are still poorly understood. Here, we present the first global analysis of the effects of biogeographic factors, the physical environment and socio-economy on the richness of naturalized and invasive alien plants. We used generalized linear mixed-effects models and variation partitioning to disentangle the relative importance of individual factors, and, more broadly, of biogeography, physical environment and socio-economy. As measures of the magnitude of permanent anthropogenic additions to the regional species pool and of species with negative environmental impacts, we calculated the relative richness of naturalized (= RRN) and invasive (= RRI) alien plant species numbers adjusted for the number of native species in 838 terrestrial regions. Socio-economic factors (per-capita gross domestic product (GDP), population density, proportion of agricultural land) were more important in explaining RRI (~50 % of the explained variation) than RRN (~40 %). Warm-temperate and (sub)tropical regions have higher RRN than tropical or cooler regions. We found that socio-economic pressures are more relevant for invasive than for naturalized species richness. The expectation that the southern hemisphere is more invaded than the northern hemisphere was confirmed only for RRN on islands, but not for mainland regions nor for RRI. On average, islands have ~6-fold RRN, and >3-fold RRI compared to mainland regions. Eighty-two islands (=26 % of all islands) harbour more naturalized alien than native plants. Our findings challenge the widely held expectation that socio-economic pressures are more relevant for plant naturalization than for invasive plants. To meet international biodiversity targets and halt the detrimental consequences of plant invasions, it is essential to disrupt the connection between socio-economic development and plant invasions by improving pathway management, early detection and rapid response.
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  • Journal Article

    Effects of forest‐use intensity on vascular epiphyte diversity along an elevational gradient 

    Guzmán‐Jacob, Valeria; Zotz, Gerhard; Craven, Dylan; Taylor, Amanda; Krömer, Thorsten; Monge‐González, María Leticia; Kreft, Holger
    Diversity and Distributions
    Aim: Understanding patterns of tropical plant diversity and their vulnerability to anthropogenic disturbance at different spatial scales remains a great challenge in ecology and conservation. Here, we study how the effects of forest‐use intensity on vascular epiphyte diversity vary along a tropical elevational gradient. Location: 3,500‐m elevational gradient along the eastern slopes of Cofre de Perote, Mexico. Methods: We studied the effects of forest‐use intensity on alpha, beta and gamma diversity of vascular epiphyte assemblages in old‐growth, degraded and secondary forests at eight study sites at 500‐m intervals along the elevational gradient. At each elevation and in each of the three forest‐use intensity levels, we established five 400‐m2 plots yielding a total of 120 plots. Results: Interactive effects of elevation and forest‐use intensity strongly impacted local‐scale patterns of vascular epiphyte diversity. Species diversity peaked at 500 as well as 1,500 m above sea level, which deviates from the previously reported humpshaped pattern. In most cases, alpha diversity did not differ significantly among forest‐ use intensity levels. However, gamma diversity was always lower in secondary forests compared to old‐growth forests across the entire elevational gradient. Within each elevational belt, beta diversity was dominated by species turnover along the forest‐use intensity gradient in the lowlands and declined with increasing elevation, where community composition became increasingly nested. Along the elevational gradient, the spatial turnover of vascular epiphyte community composition was similar among forest‐use intensity levels. Main conclusions: Our results reveal a strong interaction between forest‐use intensity and elevation, making it difficult to extrapolate findings from one elevational belt to another. Our findings highlight the value of old‐growth forest for epiphyte diversity, but also show that degraded and secondary forests—depending on the elevational belt—may maintain a high species diversity and thus play an important role in conservation planning.
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  • Journal Article

    Analyzing the relationship between historic canopy dynamics and current plant species diversity in the herb layer of temperate forests using long-term Landsat time series 

    Graf, Wanda; Kleinn, Christoph; Schall, Peter; Nauss, Thomas; Detsch, Florian; Magdon, Paul
    Remote Sensing of Environment 2019; 232: Art. 111305
    Current plant species diversity of the forest herb layer is influenced by site conditions, seed banks, stand age and historic canopy dynamics, induced for example by natural and anthropogenic disturbances. Long-term Landsat time series allow for analyzing forest canopy dynamics over several decades at a spatial resolution of 30 m. These dynamics have not been related to plant diversity in the herb layer of forests yet. Here, we related canopy layer dynamics of 132 one hectare temperate forest plots derived from Landsat time series (1985–2015) to herb layer plant species diversity observed in 2015. To quantitatively characterize the dynamics in the canopy over this period, we applied Symbolic Aggregate ApproXimation representation (SAX) to yearly NDVI time series of the plots and calculated the frequency of the representations of similar time series patterns, hereafter called SAX-metrics. We used the SAX-metrics as predictors to estimate with beta regression models the Simpson's diversity index of the herb layer of our forest plots subdivided into six forest types. Models including SAX-metrics, describing abrupt decreases in NDVI, and high, medium, or low NDVI values had pseudo R2 between 0.13 and 0.63. We conclude that disturbances, canopy closure, as well as stand age, as represented in NDVI time series, influence the diversity in the herb layer in five of the six examined forest types. Our study shows that information on historic canopy dynamics, detected from Landsat time series, can contribute to a better understanding of current herb layer diversity in some forest types. This study gives first indications on the potential of temporal metrics of Landsat time series in biodiversity research.
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  • Journal Article

    Integrating DNA Barcoding and Traditional Taxonomy for the Identification of Dipterocarps in Remnant Lowland Forests of Sumatra 

    Carneiro de Melo Moura, Carina; Brambach, Fabian; Jair Hernandez Bado, Kevin; Krutovsky, Konstantin V.; Kreft, Holger; Tjitrosoedirdjo, Sri Sudarmiyati; Siregar, Iskandar Z.; Gailing, Oliver
    Plants 2019; 8(11): Art. 461
    DNA barcoding has been used as a universal tool for phylogenetic inferences and diversity assessments, especially in poorly studied species and regions. The aim of this study was to contrast morphological taxonomy and DNA barcoding, using the three frequently used markers matK, rbcL, and trnL-F, to assess the efficiency of DNA barcoding in the identification of dipterocarps in Sumatra, Indonesia. The chloroplast gene matK was the most polymorphic among these three markers with an average interspecific genetic distance of 0.020. The results of the molecular data were mostly in agreement with the morphological identification for the clades of Anthoshorea, Hopea, Richetia, Parashorea, and Anisoptera, nonetheless these markers were inefficient to resolve the relationships within the Rubroshorea group. The maximum likelihood and Bayesian inference phylogenies identified Shorea as a paraphyletic genus, Anthoshorea appeared as sister to Hopea, and Richetia was sister to Parashorea. A better discriminatory power among dipterocarp species provided by matK and observed in our study suggests that this marker has a higher evolutionary rate than the other two markers tested. However, a combination of several different barcoding markers is essential for reliable identification of the species at a lower taxonomic lev
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  • Journal Article

    How a measure of tree structural complexity relates to architectural benefit‐to‐cost ratio, light availability, and growth of trees 

    Seidel, Dominik; Annighöfer, Peter; Stiers, Melissa; Zemp, Clara Delphine; Burkardt, Katharina; Ehbrecht, Martin; Willim, Katharina; Kreft, Holger; Hölscher, Dirk; Ammer, Christian
    Ecology and Evolution 2019; 9(12) p.7134-7142
    Aboveground tree architecture is neither fully deterministic nor random. It is likely the result of mechanisms that balance static requirements and light-capturing efficiency. Here, we used terrestrial laser scanning data to investigate the relationship between tree architecture, here addressed using the box-dimension (D b), and the architectural benefit-to-cost ratio, the light availability, and the growth of trees. We detected a clear relationship between D b and the benefit-to-cost ratio for the tested three temperate forest tree species (Fagus sylvatica L., Fraxinus excelsior L., and Acer pseudoplatanus L.). In addition, we could also show that D b is positively related to the growth performance of several tropical tree species. Finally, we observed a negative relationship between the strength of competition enforced on red oak (Quercus rubra L.) trees and their D b. We therefore argue that D b is a meaningful and integrative measure that describes the structural complexity of the aboveground compartments of a plant as well as its relation to structural efficiency (benefit-to-cost ratio), productivity, and growing conditions (competition or availability of light).
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  • Journal Article

    Evolution of interdisciplinarity in biodiversity science 

    Craven, Dylan; Winter, Marten; Hotzel, Konstantin; Gaikwad, Jitendra; Eisenhauer, Nico; Hohmuth, Martin; König‐Ries, Birgitta; Wirth, Christian
    Ecology and Evolution 2019; 9(12) p.6744-6755
    The study of biodiversity has grown exponentially in the last thirty years in response to demands for greater understanding of the function and importance of Earth's biodiversity and finding solutions to conserve it. Here, we test the hypothesis that biodiversity science has become more interdisciplinary over time. To do so, we analyze 97,945 peer‐reviewed articles over a twenty‐two‐year time period (1990–2012) with a continuous time dynamic model, which classifies articles into concepts (i.e., topics and ideas) based on word co‐occurrences. Using the model output, we then quantify different aspects of interdisciplinarity: concept diversity, that is, the diversity of topics and ideas across subdisciplines in biodiversity science, subdiscipline diversity, that is, the diversity of subdisciplines across concepts, and network structure, which captures interactions between concepts and subdisciplines. We found that, on average, concept and subdiscipline diversity in biodiversity science were either stable or declining, patterns which were driven by the persistence of rare concepts and subdisciplines and a decline in the diversity of common concepts and subdisciplines, respectively. Moreover, our results provide evidence that conceptual homogenization, that is, decreases in temporal β concept diversity, underlies the observed trends in interdisciplinarity. Together, our results reveal that biodiversity science is undergoing a dynamic phase as a scientific discipline that is consolidating around a core set of concepts. Our results suggest that progress toward addressing the biodiversity crisis via greater interdisciplinarity during the study period may have been slowed by extrinsic factors, such as the failure to invest in research spanning across concepts and disciplines. However, recent initiatives such as the Intergovernmental Science‐Policy Platform on Biodiversity and Ecosystem Services (IPBES) may attract broader support for biodiversity‐related issues and hence interdisciplinary approaches to address scientific, political, and societal challenges in the coming years.
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  • Journal Article

    Detecting the genetic basis of local adaptation in loblolly pine ( Pinus taeda L.) using whole exome‐wide genotyping and an integrative landscape genomics analysis approach 

    Lu, Mengmeng; Loopstra, Carol A.; Krutovsky, Konstantin V.
    Ecology and Evolution 2019; 9(12) p.6798-6809
    In the Southern United States, the widely distributed loblolly pine contributes greatly to lumber and pulp production, as well as providing many important ecosystem services. Climate change may affect the productivity and range of loblolly pine. Nevertheless, we have insufficient knowledge of the adaptive potential and the genetics underlying the adaptability of loblolly pine. To address this, we tested the association of 2.8 million whole exome‐based single nucleotide polymorphisms (SNPs) with climate and geographic variables, including temperature, precipitation, latitude, longitude, and elevation data. Using an integrative landscape genomics approach by combining multiple environmental association and outlier detection analyses, we identified 611 SNPs associated with 56 climate and geographic variables. Longitude, maximum temperature of the warm months and monthly precipitation associated with most SNPs, indicating their importance and complexity in shaping the genetic variation in loblolly pine. Functions of candidate genes related to terpenoid synthesis, pathogen defense, transcription factors, and abiotic stress response. We provided evidence that environment‐associated SNPs also composed the genetic structure of adaptive phenotypic traits including height, diameter, metabolite levels, and gene transcript abundance. Our study promotes understanding of the genetic basis of local adaptation in loblolly pine and provides promising tools for selecting genotypes adapted to local environments in a changing climate.
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  • Journal Article

    A Reference Genome Sequence for the European Silver Fir ( Abies alba Mill.): A Community-Generated Genomic Resource 

    Mosca, Elena; Cruz, Fernando; Gómez-Garrido, Jèssica; Bianco, Luca; Rellstab, Christian; Brodbeck, Sabine; Csilléry, Katalin; Fady, Bruno; Fladung, Matthias; Fussi, Barbara; et al.
    Gömöry, DušanGonzález-Martínez, Santiago C.Grivet, DelphineGut, MartaHansen, Ole KimHeer, KatrinKaya, ZekiKrutovsky, Konstantin V.Kersten, BirgitLiepelt, SaschaOpgenoorth, LarsSperisen, ChristophUllrich, Kristian K.Vendramin, Giovanni G.Westergren, MarjanaZiegenhagen, BirgitAlioto, TylerGugerli, FelixHeinze, BertholdHöhn, MariaTroggio, MichelaNeale, David B.
    G3: Genes, Genomes, Genetics 2019; 9(7) p.2039-2049
    Silver fir (Abies alba Mill.) is a keystone conifer of European montane forest ecosystems that has experienced large fluctuations in population size during during the Quaternary and, more recently, due to land-use change. To forecast the species' future distribution and survival, it is important to investigate the genetic basis of adaptation to environmental change, notably to extreme events. For this purpose, we here provide a first draft genome assembly and annotation of the silver fir genome, established through a community-based initiative. DNA obtained from haploid megagametophyte and diploid needle tissue was used to construct and sequence Illumina paired-end and mate-pair libraries, respectively, to high depth. The assembled A. alba genome sequence accounted for over 37 million scaffolds corresponding to 18.16 Gb, with a scaffold N50 of 14,051 bp. Despite the fragmented nature of the assembly, a total of 50,757 full-length genes were functionally annotated in the nuclear genome. The chloroplast genome was also assembled into a single scaffold (120,908 bp) that shows a high collinearity with both the A. koreana and A. sibirica complete chloroplast genomes. This first genome assembly of silver fir is an important genomic resource that is now publicly available in support of a new generation of research. By genome-enabling this important conifer, this resource will open the gate for new research and more precise genetic monitoring of European silver fir forests.
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  • Journal Article

    Genetic diversity of common guava in Kenya: an underutilized naturalized fruit species 

    Chiveu, J.C.; Mueller, M.; Krutovsky, K.V.; Kehlenbeck, K.; Pawelzik, E.; Naumann, M.
    Fruits 2019; 74(5) p.236-248
    Introduction – Common guava (Psidium guajava L.) fruit has a significant nutritional and medicinal potential besides its economic importance. Currently, the world guava fruit production is based only on a few cultivars. It is not clear when guava was introduced in Kenya, but the species is currently naturalized. There is no detailed study on guava diversity in Kenya to enable a comparison with other guava-producing countries for purposes of characterization and improvement. Objectives – The main objective of the study was to analyse the genetic diversity and differentiation of guava accessions from four geographically diverse regions of Kenya. Materials and methods – The genetic diversity of 177 guava accessions collected from four regions of Kenya (Coast, Eastern, Rift Valley, and Western) was assessed using 13 simple sequence repeat (SSR) markers. Results and discussion – The neighbour-joining (NJ) phylogenetic tree revealed most accessions generally clustering into multiple weakly supported groups. Only 46 out of 177 accessions were supported by bootstrap values above 50% and clustered in twenty-two groups, each comprising two or three individual accessions only. The principle coordinates analysis (PCoA) did not reveal clear-cut clusters along geographic origins or fruit flesh colour of the samples. The fixation index (FIS) was very high (FIS=0.511), which could be due to a high level of either inbreeding and/or differentiation. The white-fleshed accessions were clustered together with the red-fleshed types, indicative of some degree of genetic similarity, but also pointing to a possibility of shared ancestry between them. Conclusion – For guava conservation and selection for breeding and utilization purposes in Kenya, sampling of many individual accessions covering the geographical range of the species is recommended.
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  • Journal Article

    Physiological Responses to Abiotic and Biotic Stress in Forest Trees 

    Polle, Andrea; Rennenberg, Heinz
    Forests 2019; 10(9): Art. 711
    Forests fulfill important ecological functions by sustaining nutrient cycles and providing habitats for a multitude of organisms. They further deliver ecosystem services such as carbon storage, protection from erosion, and wood as an important commodity. Trees have to cope in their environment with a multitude of natural and anthropogenic forms of stress. Resilience and resistance mechanisms to biotic and abiotic stresses are of special importance for long-lived tree species. Since trees exist for many decades or even centuries on the same spot, they have to acclimate their growth and reproduction to constantly changing atmospheric and pedospheric conditions. In this special issue, we invited contributions addressing the physiological responses of forest trees to a wide array of different stress factors. Among the eighteen papers published, seventeen covered drought or salt stress as major environmental cues, highlighting the relevance of this topic in times of climate change. Only one paper studied cold stress [1]. The dominance of drought and salt stress studies underpins the need to understand tree responses to these environmental threats from the molecular to the ecophysiological level. The papers contributing to this Special Issue cover these scientific aspects in different areas of the globe and encompass conifers as well as broadleaf tree species. In addition, two studies deal with bamboo (Phyllostachys sp., [1,2]). Bamboo, although botanically belonging to grasses, was included because its ecological functions and applications are similar to those of trees.
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  • Journal Article

    The NLRX R package: A next‐generation framework for reproducible NetLogo model analyses 

    Salecker, Jan; Sciaini, Marco; Meyer, Katrin M.; Wiegand, Kerstin
    Methods in Ecology and Evolution
    1. Agent‐based models find wide application in all fields of science where large‐scale patterns emerge from properties of individuals. Due to increasing capacities of computing resources it was possible to improve the level of detail and structural realism of nextgeneration models in recent years. However, this is at the expense of increased model complexity, which requires more efficient tools for model exploration, analysis and documentation that enable reproducibility, repeatability and parallelization. NetLogo is a widely used environment for agent‐based model development, but it does not provide sufficient built‐in tools for extensive model exploration, such as sensitivity analyses. One tool for controlling NetLogo externally is the r‐package RNetLogo. However, this package is not suited for efficient, reproducible research as it has stability and resource allocation issues, is not straightforward to be setup and used on high performance computing clusters and does not provide utilities, such as storing and exchanging metadata, in an easy way. 2. We present the r‐package nlrx, which overcomes stability and resource allocation issues by running NetLogo simulations via dynamically created XML experiment files. Class objects make setting up experiments more convenient and helper functions provide many parameter exploration approaches, such as Latin Hypercube designs, Sobol sensitivity analyses or optimization approaches. Output is automatically collected in user‐friendly formats and can be post‐processed with provided utility functions. nlrx enables reproducibility by storing all relevant information and simulation output of experiments in one r object which can conveniently be archived and shared. 3. We provide a detailed description of the nlrx package functions and the overall workflow. We also present a use case scenario using a NetLogo model, for which we performed a sensitivity analysis and a genetic algorithm optimization. 4. The nlrx package is the first framework for documentation and application of reproducible NetLogo simulation model analysis.
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  • Journal Article

    Low-cost eddy covariance: a case study of evapotranspiration over agroforestry in Germany 

    Markwitz, Christian; Siebicke, Lukas
    Atmospheric Measurement Techniques 2019; 12(9) p.4677-4696
    Heterogeneous land surfaces require multiple measurement units for spatially adequate sampling and representative fluxes. The complexity and cost of traditional eddy covariance (EC) set-ups typically limits the feasible number of sampling units. Therefore, new low-cost eddy covariance systems provide ideal opportunities for spatially replicated sampling. The aim of this study was to test the performance of a compact, low-cost pressure, temperature and relative humidity sensor for the application of evapotranspiration measurements by eddy covariance over agroforestry and conventional agriculture in Germany. We performed continuous low-cost eddy covariance measurements over agroforestry and conventional agriculture for reference at five sites across northern Germany over a period of 2 years from 2016 to 2017. We conducted side-by-side measurements using a roving enclosed-path eddy covariance set-up to assess the performance of the low-cost eddy covariance set-up. Evapotranspiration measured with low-cost eddy covariance compared well with fluxes from conventional eddy covariance. The slopes of linear regressions for evapotranspiration comparing low-cost and conventional eddy covariance set-ups ranged from 0.86 to 1.08 for 5 out of 10 sites, indicating a 14 % flux underestimation and a 8 % flux overestimation relative to the conventional eddy covariance set-up, respectively. Corresponding coefficients of determination, R2, ranged from 0.71 to 0.94 across sites. The root-mean-square error for differences between latent heat fluxes obtained by both set-ups were small compared to the overall flux magnitude, with a mean and standard deviation of 34.23±3.2 W m−2, respectively, across sites. The spectral response characteristics of the low-cost eddy covariance set-up were inferior to the eddy covariance set-up in the inertial sub-range of the turbulent spectrum. The water vapour flux co-spectrum of the low-cost eddy covariance set-up underestimated the theoretical slope of −4/3 , stronger than the conventional eddy covariance set-up. This underestimation was mainly caused by the limited response time of the low-cost thermohygrometer being longer than 1 s. We conclude that low-cost eddy covariance sensors are an alternative to conventional eddy covariance sensors when, first, replicates are required and, second, the spatial variability of fluxes of the ecosystems of interest is larger than above-reported set-up-specific differences in fluxes.
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  • Journal Article

    Intraspecific Competition Affects Crown and Stem Characteristics of Non-Native Quercus rubra L. Stands in Germany 

    Burkardt, Katharina; Annighöfer, Peter; Seidel, Dominik; Ammer, Christian; Vor, Torsten
    Forests 2019; 10(10): Art. 846
    Accurate guidelines for silvicultural management of exotic tree species in Germany are sparse. For example, northern red oak (Quercus rubra L.) is the most commonly planted exotic deciduous tree species in Germany, but its response to varying levels of competition intensity has not yet been adequately explored. Here, we used terrestrial laser scanning to non-destructively examine the responses of stem and crown characteristics of Quercus rubra to intraspecific competition. A total of 100 dominant red oak trees were investigated in ten pure red oak stands, located in five federal states of Germany. The external stem quality characteristics namely stem non-circularity and bark anomalies decreased with increasing tree competition. Also, the crown characteristics crown volume, crown surface area, maximum crown area, crown length, and branch length declined by the degree of individual tree competition. We conclude that individual tree properties can be controlled by competition intensity, resulting in improved timber quality as shown for other tree species.
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  • Journal Article

    Land Use Change and Water Quality Use for Irrigation Alters Drylands Soil Fungal Community in the Mezquital Valley, Mexico. 

    Lüneberg, Kathia; Schneider, Dominik; Brinkmann, Nicole; Siebe, Christina; Daniel, Rolf
    Frontiers in Microbiology 2019; 10: Art. 1220
    Soil fungal communities provide important ecosystem services, however, some soil borne representatives damage agricultural productivity. Composition under land-use change scenarios, especially in drylands, is rarely studied. Here, the soil fungal community composition and diversity of natural shrubland was analyzed and compared with agricultural systems irrigated with different water quality, namely rain, fresh water, dam-stored, and untreated wastewater. Superficial soil samples were collected during the dry and rainy seasons. Amplicon-based sequencing of the ITS2 region was performed on total DNA extractions and used the amplicon sequence variants to predict specific fungal trophic modes with FUNGuild. Additionally, we screened for potential pathogens of crops and humans and assessed potential risks. Fungal diversity and richness were highest in shrubland and least in the wastewater-irrigated soil. Soil moisture together with soil pH and exchangeable sodium were the strongest drivers of the fungal community. The abundance of saprophytic fungi remained constant among the land use systems, while symbiotic and pathogenic fungi of plants and animals had the lowest abundance in soil irrigated with untreated wastewater. We found lineage-specific adaptations to each land use system: fungal families associated to shrubland, rainfed and part of the freshwater were adapted to drought, hence sensitive to exchangeable sodium content and most of them to N and P content. Taxa associated to freshwater, dam wastewater and untreated wastewater irrigated systems show the opposite trend. Additionally, we identified potentially harmful human pathogens that might be a health risk for the population.
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  • Journal Article

    Towards Conservation of Genetic Variation of Tropical Tree Species With Differing Successional Status: The Case of Mansonia altissima A. Chev and Triplochiton scleroxylon K. Schum 

    Akinnagbe, Akin; Gailing, Oliver; Finkeldey, Reiner; Lawal, Amadu
    Tropical Conservation Science 2019; 12 p.1-9
    Two important West African timber tree species with differing successional status, Mansonia altissima A. Chev and Triplochiton scleroxylon K. Schum were investigated in this study. Triplochiton scleroxylon is a pioneer species found in open forests, whereas Mansonia altissima is a nonpioneer light-demanding tree species occurring in closed forests. Amplified fragment length polymorphism markers were used to compare the genetic diversities of these two timber species in stands with different degrees of human impact (isolated forest patch, logged forest, farmland, plantation, and primary forest). Contrasting effects of human impact on genetic diversity were detected for these two timber species. The results suggested severe effects of human impact on the genetic diversity of Mansonia altissima, a nonpioneer species. However, no adverse effect was recorded in Triplochiton scleroxylon, a pioneer species. These findings indicate that nonpioneer tree species could be more prone to genetic erosion than pioneer tree species as a result of adverse human impacts. Therefore, conservation of genetic diversity in both pioneer and nonpioneer tree species populations would likely necessitate different measures.
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  • Journal Article

    Assessment of Genetic Diversity in Differently Colored Raspberry Cultivars Using SSR Markers Located in Flavonoid Biosynthesis Genes 

    Lebedev, Vadim G.; Subbotina, Natalya M.; Maluchenko, Oleg P.; Krutovsky, Konstantin V.; Shestibratov, Konstantin A.
    Agronomy 2019; 9(9): Art. 518
    Raspberry is a valuable berry crop containing a large amount of antioxidants that correlates with the color of the berries. We evaluated the genetic diversity of di erently colored raspberry cultivars by the microsatellite markers developed using the flavonoid biosynthesis structural and regulatory genes. Among nine tested markers, seven were polymorphic. In total, 26 alleles were found at seven loci in 19 red (Rubus idaeus L.) and two black (R. occidentalis L.) raspberry cultivars. The most polymorphic marker was RiMY01 located in the MYB10 transcription factor intron region. Its polymorphic information content (PIC) equalled 0.82. The RiG001 marker that previously failed to amplify in blackberry also failed in black raspberry. The raspberry cultivar clustering in the UPGMA dendrogram was unrelated to geographical and genetic origin, but significantly correlated with the color of berries. The black raspberry cultivars had a higher homozygosity and clustered separately from other cultivars, while at the same time they di ered from each other. In addition, some of the raspberry cultivars with a yellow-orange color of berries formed a separate cluster. This suggests that there may be not a single genetic mechanism for the formation of yellow-orange berries. The data obtained can be used prospectively in future breeding programs to improve the nutritional qualities of raspberry fruits.
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  • Journal Article

    Soil phosphorus supply controls P nutrition strategies of beech forest ecosystems in Central Europe 

    Lang, F.; Krüger, J.; Amelung, W.; Willbold, S.; Frossard, E.; Bünemann, E. K.; Bauhus, J.; Nitschke, R.; Kandeler, E.; Marhan, S.; et al.
    Schulz, S.Bergkemper, F.Schloter, M.Luster, J.Guggisberg, F.Kaiser, K.Mikutta, R.Guggenberger, G.Polle, A.Pena, R.Prietzel, J.Rodionov, A.Talkner, U.Meesenburg, H.von Wilpert, K.Hölscher, A.Dietrich, H. P.Chmara, I.
    Biogeochemistry 2017; 136(1) p.5-29
    Phosphorus availability may shape plant–microorganism–soil interactions in forest ecosystems. Our aim was to quantify the interactions between soil P availability and P nutrition strategies of European beech (Fagus sylvatica) forests. We assumed that plants and microorganisms of P-rich forests carry over mineral-bound P into the biogeochemical P cycle (acquiring strategy). In contrast, P-poor ecosystems establish tight P cycles to sustain their P demand (recycling strategy). We tested if this conceptual model on supply-controlled P nutrition strategies was consistent with data from five European beech forest ecosystems with different parent materials (geosequence), covering a wide range of total soil P stocks (160–900 g P m−2; <1 m depth). We analyzed numerous soil chemical and biological properties. Especially P-rich beech ecosystems accumulated P in topsoil horizons in moderately labile forms. Forest floor turnover rates decreased with decreasing total P stocks (from 1/5 to 1/40 per year) while ratios between organic carbon and organic phosphorus (C:Porg) increased from 110 to 984 (A horizons). High proportions of fine-root biomass in forest floors seemed to favor tight P recycling. Phosphorus in fine-root biomass increased relative to microbial P with decreasing P stocks. Concomitantly, phosphodiesterase activity decreased, which might explain increasing proportions of diester-P remaining in the soil organic matter. With decreasing P supply indicator values for P acquisition decreased and those for recycling increased, implying adjustment of plant–microorganism–soil feedbacks to soil P availability. Intense recycling improves the P use efficiency of beech forests.
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