Browsing by Subject "Biodiversity"

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Agricultural diversification of biogas crop cultivation
(2018) von Cossel, Moritz; Lewandowski, Iris
For all types of agricultural land-use, more diverse cropping systems are required, with respect to the maintenance of ecosystem values such as biodiversity conservation and climate change adaptation. This need for greater agricultural diversity is clearly illustrated by biogas crop cultivation. In Germany, maize currently dominates biogas crop cultivation due to its outstanding methane yield performance. However, the ecosystem value of maize cultivation decreases if good agricultural practices are ignored. Additionally, the poor aesthetical value of maize has led to biogas production gaining a negative reputation in society. To increase the diversity of biogas crop cultivation, alternative biogas crops such as amaranth and wild plant mixtures need to be investigated with respect to both yield performance and biogas substrate quality. The research objective of this study was the development of strategies for agricultural diversification of biogas crop cultivation. For this purpose, the following research questions were formulated: 1. How does amaranth perform as a biogas crop compared to maize and what are the major opportunities for and obstacles to the large-scale implementation of amaranth cultivation? 2. How does the spatial diversification ‘legume intercropping’ perform in amaranth compared to maize and what are the major opportunities for and obstacles to its practical implementation? 3. How do perennial wild plant mixtures perform in biomass production with respect to yield, quality and species diversity in the long term and what are the relevant agronomic factors? 4. How do available models perform in the prediction of specific methane yield of different crops based on their lignocellulosic biomass composition and how could they be improved? To address research questions 1 and 2, field trials with amaranth and maize were conducted in southwest Germany in the years 2014 and 2015. Amaranth established well in both years. Its dark red inflorescences attracted many insects such as honeybees, wild bees and bumble bees. Therefore, a systematic implementation of amaranth into biogas crop rotations could significantly improve their socio-ecological value in terms of biodiversity conservation and landscape beauty. However, amaranth showed significantly lower dry matter yields (DMY) and specific methane yields (SMY), together resulting in lower methane yields than maize in both years. Therefore, breeding and an optimization of agricultural practices such as sowing density, planting geometry and fertilization management are required to make amaranth more competitive in comparison to maize. To address research question 2, the amaranth field trials mentioned above also included treatments of legume intercropping with runner bean (RB, Phaseolus vulgaris L.) and white clover (WC, Trifolium repens, L.). The RB and WC developed equally well in amaranth and maize each year. For both amaranth and maize, the RB share of total DMY was low (5-10%) and did not significantly affect the total DMY. By contrast, WC had a significant negative effect on the DMY. Overall, the spatial diversification ‘legume intercropping’ could considerably improve the socio-ecological value of amaranth cultivation in terms of biodiversity conservation, greenhouse gas (GHG) mitigation and soil protection. For research question 3, two different wild plant mixtures (WPM) were cultivated on three sites in southwest Germany from the years 2011 to 2015. At each location, the WPM showed great potential for both biodiversity conservation and ecosystem resilience. Numerous insect species were observed in the WPM stands each year, indicating WPM as a relevant cropping system for habitat networking. Furthermore, the aesthetic appearance of the WPM stands over the years demonstrated the potential positive effect WPM cultivation could have on the public perception of biogas production. The DMY of the WPM varied strongly depending on (i) the initial composition of species sown, (ii) the establishment procedure, (iii) the environmental conditions, (iv) the pre-crop, and (v) the number of predominant species. WPM were found to have low demands for fertilization and crop protection. Thus, WPM appear a promising low-input cropping system for the promotion of biodiversity conservation, habitat networking, soil and water protection, GHG mitigation and climate change adaptation. However, high DMY gaps remain a challenge for the practical inclusion of WPM in existing biogas cropping systems. With respect to research question 4, a meta-analysis revealed that available models proved to be much less precise than expected. Although outperforming all available models, the correlation of the new models was still low (up to r = 0.66). It was also found that non-linear terms are of less importance than crop-specific regressors including the intercept. This indicates that across-crop models including crop-specific configurations could help to improve the identification of alternative crops and cropping systems for a more diverse biogas crop cultivation in the future.
Elucidating the megadiversity of Chalcidoidea (Hymenoptera) with a multi-taxonomic approach
(2022) Haas, Michael; Krogmann, Lars
With over 22,500 described and up to 500,000 estimated species, the jewel wasps (Chalcidoidea: Hymenoptera) are among the most species-rich insect lineages. Their evolutionary success is tightly linked to their parasitoid biology, having evolved to utilize a wide array of different arthropod hosts. Additionally, secondary phytophagy evolved several times within this superfamily. Although new approaches are employed in integrative taxonomic research, progress to decipher the megadiversity of this taxon, including their evolution, is still limited. With this work, the diversity of the superfamily is studied at two evolutionary key points in time. The evolutionary origin of Chalcidoidea is investigated in the Cretaceous and the resulting diversity since then is examined in the present. Different systematic levels will be elucidated with the help of integrative taxonomic methods. In the first chapter, the fossil origins of jewel wasps are addressed, around the middle of the Cretaceous period 110 million years ago. The morphology of a putative early chalcidoid specimen is studied, as it is highly informative for chalcidoid evolution due to its age. Based on those results, its phylogenetic placement is critically examined. The specimen is assumed to be one of the oldest described chalcidoid fossils, Parviformosus wohlrabeae Barling et al., 2013. It is a key fossil because of its age and putative assignment to the polyphyletic family Pteromalidae and could therefore be a valuable voucher for dating modern phylogenies. A precise redescription of the fossil was conducted and its morphology and phylogenetic position was discussed. No synapomorphic characters could be identified, warranting an inclusion in an already established chalcidoid family. In fact, none of the autapomorphies for Chalcidoidea could be recognized, necessitating a revised systematic placement in the Proctotrupomorpha. In the second chapter, several fossils in amber are described that grant insights in the early evolution of Chalcidoidea and the morphological diversity of Cretaceous lineages. Morphological characters are studied to answer the question of plesiomorphic character states in Chalcidoidea, aiding to understand their early evolution. The phylogenetic placement of these fossils is discussed, to provide hypotheses on the diversification of the superfamily, which so far has only few fossil representatives described from this time. Four fossils are made scientifically available that were found in 99 million year old Burmese amber. Those specimens are described in a new, extinct family, the Diversinitidae. This family exhibits a unique combination of plesiomorphic characters, not present in any other chalcidoid taxon, but lacks apomorphic characters. In total, three new genera and three new species are delimited and described. Phylogenetically relevant characters like the fully developed funicular segments, possessing multiporous plate sensilla, or the peg like cerci that improve our understanding of the early evolution of Chalcidoidea, are discussed based on the newly established family. A phylogenetic analysis based on morphological characters was performed. This analysis supported the monophyly of Diversinitidae, but left its exact systematic position within Chalcidoidea open. In the third chapter the focus shifts from the early evolution of Chalcidoidea towards the extant fauna, representing the diversity evolved since the Cretaceous. Exemplary, in the speciose family Pteromalidae the unknown diversity is examined to better understand the undiscovered species richness of parasitoid wasps. DNA barcoding is used to record and help identify previously unknown genera and species in Germany. Compared to the already known pteromalid fauna, 17 genera and 41 species are added as new records for Germany and the males of two species are described anew. The identified DNA barcodes were made available to enable the genetic identification of those species that have a high potential as indicators for nature conservation efforts due to their high host specificity. In the fourth chapter, the pertinent problem of cryptic diversity in Chalcidoidea is investigated. Via an extensive integrative taxonomic approach, the morphological species hypothesis is tested for one of the most abundant pteromalid species in Europe, Spintherus dubius. In this example, the benefit of combining different methods for species discovery and delimitation is highlighted. Genetic analyses of S. dubius reveal discrepancies between the morphological species concept and molecular data, indicating two potential species instead of one. The usage of an advanced morphological method, the multivariate ratio analysis, results in a confirmation of the molecular results, also exposing distinctive morphological characters per taxonomic unit. The examination of the host spectrum through rearing experiments further substantiates these findings, by revealing different host parasitoid affiliations. Altogether, this thesis showed that it is necessary to combine methods and examine different evolutionary points in time, to better understand the diversity of parasitoid lineages. Fossil taxa are important study subjects to examine the character evolution of any taxon, laying the base for phylogenetic research. The study of Diversinitidae highlights the plasticity of character states in Chalcidoidea, also providing evidence for plesiomorphic states. Their encompassing description and the redescription of P. wohlrabeae allow their incorporation into phylogenetic studies, to serve as solid anchor points in dating lineages and morphological evolution on the way towards extant diversity. Examining the extant fauna of Pteromalidae revealed the amount of diversity of species, for which the biology is often unknown. It is shown that molecular methods aid in the discovery of this diversity, opening possibilities for further research. It is affirmed that hidden diversity is even pertinent in abundant, well known species, with S. dubius being an example of cryptic diversity unveiled by integrative taxonomy.
Fernerkundungsgestützte Analyse und Bewertung ökologischer Auswirkungen des Anbaus von Bioenergiepflanzen auf die Agro-Biodiversität anhand der Modellierung der Habitatansprüche der Feldlerche (Alauda arvensis)
(2017) Schlager, Patric; Schmieder, Klaus
For the first time in 2002, the transformation of the conventional energy system into a system based on renewable energies was politically and legally decided in Germany. On the regional level numerous communities and municipalities followed this decision by voicing their own political resolutions, addressing the coverage of energy consumption with renewable energies. Their implementation is accompanied by a spatial expansion of bioenergy crops which lead to a controversial discussion about food safety, biodiversity and landscape change. Framed by the above mentioned discussion, this study assesses potential changes of skylark (Alauda arvensis) occurrence caused by a spatial expansion of bioenergy crops in the municipality of Schwäbisch Hall, Germany. The skylark was selected due to the comprehensive state of research about skylarks, their endangerment (“Red list of German breeding birds”), and the status as umbrella species for open agricultural landscapes (skylarks typically avoid vertical structures like hedges or edges of forests). The latter emphasizes their role as representatives for other species which are potentially affected by an expansion of bioenergy crops. This study is based on a stratified bird monitoring scheme of Baden-Württemberg, which was developed during a project that aimed to set up an indicator for species richness and was financed by the Bundesministerium für Ernährung, Landwirtschaft und Verbraucherschutz (BMELV). From the bird monitoring scheme, the stratum, which covers the municipality of Schwäbisch Hall, was extracted and served as a base for the development of a Generalized Linear Habitat Model of the skylark. In order to assess potential habitat changes caused by an expansion of bioenergy crops, Schwäbisch Hall was mapped with an airborne remote sensing technology in 2011. The resulting aerial images were transformed into orthophotos and later classified (focusing on agricultural areas) with an object oriented image analysis approach. Based on the outcomes of the habitat association model and the land use classification, skylark territories were predicted for 1 km² plots covering Schwäbisch Hall. For an in-depth understanding of ecological impacts from expanded bioenergy cropping, a bioenergy scenario was developed considering § 17 BBodSchG (national soil protection act) and regional food security. Based on the scenario, skylark territories were predicted for 1 km² plots covering Schwäbisch Hall. The most reasonable habitat association model resulted in a negative binomial Generalized Linear Model with the predictors winter sown crops and mean patch size per plot. Model performance was assessed by Wald z-statistics with p-values, ANOVA, explained variance, theta, residuals, AIC, and independent field data. Field data was only available for one plot. Therefore, the field data only indicate model performance. The comparison of the model predictions with the field data resulted in an accuracy of 92.21%. The land use classification resulted in the following five classes: 1. winter sown crops (33985.78 ha), 2. maize (9621.36 ha), rapeseed (2952.36 ha), unidentified crops (7244.18 ha), and grassland (30720.88 ha). Grasslands were not mapped by remote sensing techniques, but taken from a digital landscape model. Accuracy assessment showed an overall accuracy of 89.16 % and 0.78 kappa statistics. Prediction of skylark territories based on the land use classification of 2011 resulted in 46269 territories, or a mean density of 8.4 territories per 10 ha on agricultural areas and 5.4 territories per 10 ha on agricultural and grassland combined areas. The scenario assumed a three partite crop rotation (maize, rapeseed, winter sown crops) and a mean value of 0.17 ha per inhabitant for food security. Areas for fodder production were considered in course of the calculation of food security because Schwäbisch Hall is characterized by many livestock farms, which made it necessary to avoid conflicts between potential bioenergy sites and areas for fodder production. Considering the above mentioned assumptions, Schwäbisch Hall has a bioenergy potential of 5955 ha for maize and 15033 ha for rapeseed cropping. The results of the bioenergy scenario were randomly distributed to the land use polygons which resulted from the remote sensing analysis. With that, prediction of skylark territories based on the bioenergy scenario was feasible. Skylark territories for the bioenergy scenario resulted in 36472 territories, or a mean value of 6.8 territories per 10 ha on agricultural areas and 4.3 territories per 10 ha on agricultural and grassland combined areas. Considering both land use options, skylark territories declined by 8797 in total numbers or by 19.43 % in relative numbers. In addition to the land use options described above, landscape structure and territory distribution were analyzed based on six landscape units (Naturräumliche Haupteinheiten) covering the municipality of Schwäbisch Hall. The analysis revealed an agriculturally dominated northwestern part, with high numbers and mean values of skylark territories, and a grassland/forest dominated southeastern part, with lower numbers and mean values of skylark territories. The relative decline of these territories between the two land use options within the landscape units resulted approximately in 22 % in the northwestern and approximately 11-15 % in the southeastern part. The results indicate that an expansion of bioenergy crops will have negative effects on breeding birds in open agricultural landscapes which already suffer from degraded habitat conditions. Based on the assumptions of this study, skylark territories will decline by approximately 20 % in comparison to 2011. Yet, considering the results of the indicator report of the German National Strategy on Biodiversity (BMU 2010) and the European Bird Census Council the baseline of 2011 already represents a degraded situation in terms of habitat quality for agricultural breeding birds.
Functional larval-parasitoid biodiversity in apple orchards as benchmark for management intensity and potential instrument for ecological amelioration of Iranian apple production
(2019) Lashkari-Bod, Abdullah; Zebitz, Claus P. W.
Although a consensus through the concept of sustainable agricultural production and its indicators to assess its functionality varies, it is expected to be long-term and reliable. The sustainability would change temporarily and spatially. It is influenced by political, social and economical is-sues, which reveals its interdisciplinary essence in concert with farming strategies and practices to produce human food. The management of plant protection is capable to impose unsustainability into farming system. The frequency and intensity of unsustainable practices would result into devastating effects on diversity and abundance of beneficial arthropods. The communities of natural enemy may promote sustainable management, but the anthropogenic interventions such as broad-spectrum pesticide applications would distort the essence of self-monitoring of natural invertebrates as regulators. The conventional agricultural management makes the habitats to be simplified through food webs and ecological complexities, which lead to species loss (extinction or emigration) and consequently to species interactions (connectance). The ecologically based management such as integrated pest management (IPM) would focus to maintain species and increase diversity in natural communities, which contributes to sustainable approach as alternative versus conventional agriculture. The negative effects of chemical pesticides would dramatically decline the ecosystem process and affect the energy flow among different trophic levels, which is manifested as functional rates in local or regional scale of ecosystem. The human-manipulated areas create negative consequences on the ecosystem functionality through vanishing the key natural resources (i.e. shelter, food provision, and alternative host prey), which affect maintaining natural enemy communities. The complementarity effects of antagonist communities can lead a synergetic impact on pest control, when biodiversity is conserved through vegetation, rational bio-pesticide application, and ecological infrastructure, the functional traits (richness and evenness) among interacting species will be improved. Furthermore, the intensified agriculture would arise pest outbreaks or convert a secondary and unimportant pest into a serious one. The antagonistic communities may represent as bio-indicators. The presence or absence of higher trophic levels and their complexes would reflect biotic or abiotic changes in the environment, which would eventually be expressed as parasitism or consumption rate. The scope of current research is limited to indicators of sustainability through pest management and does not comply a holistic approach on ecological, political, social, and economical managements. The preliminary results focus on the status quo of plant protection in Iran and biodiversity indices in Germany used to compare the different farm systems to show how the management can affect the community components and their interactions. The environmental and anthropogenic impacts on biodiversity of beneficial arthropods in different orchard management conducted in Germany, where the accessibility of abandoned apple orchards is more prevalent than Iran. To evaluate the impact of conventional intensive management vs. ecologically based sustainable practices on invertebrate beneficial community, a comparative study was conducted to assess food web pattern of larval-parasitoid communities, biodiversity indices, and parasitism rate in response to apple orchard by four different managements. Field samplings were occurred during 2011-2015 in Baden-Württemberg, Germany. The orchard managements were distinguished based on the frequency and intensity of pesticide applications into the farming system. The categories of orchard management were managed (organic and integrated), and Streuobst (semi-abandoned orchard), which were situated in Denzlingen, Emmendingen, Goldener Grund, Hohenheim research center, Ilsfeld, Lake Constance, Neuhausen, Plieningen, Rommelshausen, and Scharnhausen. The sampling was conducted by installation of corrugated cardboard and random observation to collect larval caterpillars (Tortricidae and Gelechiidae). The collected samples were transferred to lab to rear adult parasitoids and further studies on taxonomic affiliation. Out of 7,923 healthy host larvae collected, totally 324 parasitoid individuals from three sub-families of Braconidae, Ichneumonidae, and Perilampidae were found. Four parasitoid species were found positive host-density dependent, the rest of the parasitoid species showed no densi-ty-dependency or were found in too small numbers. The highest richness, abundance, and evenness of larval-parasitoids were found in Streuobst orchards (i.g. Plieningen), which received no to minimal pesticide inputs. The interaction diversity of food webs (connectance) in Streuobst showed the highest number of trophic links in response to other orchard managements where the commercial (conventional) orchards harbor no to the least biodiversity indices of beneficial arthropods. Percentage similarity also assessed to depict the similarity of larval-parasitoid community structures in different managements. It was revealed the orchards with the same management contain similar parasitoid compositions. To describe and analyze the information on apple growing management, circumstances of plant protection, pest status, and major obstacles to initialize sustainable production in Iran, a questionnaire was designed to survey 39 apple growers from East-Azerbaijan, Fars, Isfahan, Tehran, and W. Azerbaijan in July 2014. It was found that management of the orchards mostly is under the supervision of the apple growers. Farmers in Isfahan suffer a road infrastructure to have an access to the nearest market to sell their product indicating an economic monopoly. The distance to experts affects the intensity of pesticide application by farmers. The conventional agriculture is prevailing in all provinces and access to bio-pesticides highly limited to Tehran. Totally 29 pesticides were used against different fruit pests in Iran. The most damage intensities occurred by pests in province scale and weeds in regional scale. The outbreak of secondary pest Tetranychus urticae as key one indicates human perturbations in Iran’s farming system. Tehran province enjoyed diverse apple cultivars contrary to other provinces, which are poor in diversification. The predominant outlook to choose a cultivar among apple growers was marketing.
Integrative taxonomy of platygastrine wasps of Germany
(2023) Awad, Jessica; Krogmann, Lars
In the context of the sixth mass extinction, our understanding of insect decline is severely limited by a lack of information on biodiversity. Many highly abundant and diverse insect groups remain unidentifiable to species or even to genus. The parasitoid wasp superfamily Platygastroidea is one such “dark taxon”. The taxonomic impediment is especially severe in the Palearctic Platygastrinae due to the proliferation of names with vague concepts. Platygastrine wasps parasitize the hyper-diverse Cecidomyiidae (Diptera), suggesting that their species richness may be correspondingly high. Revisionary work is needed to identify named species and to discover new ones. This work applies integrative taxonomic methods to address the most pressing problems within the subfamily. The research presented in this dissertation focuses on Europe, particularly Germany, which is the current center of insect decline research as well as a historical center of platygastrine taxonomy. As part of this work, historical descriptions and their associated type material were examined and clarified so that further revisionary work can occur. The dissertation is structured in five chapters, of which two are published and three are unpublished. The first chapter reviews 18 genera of Platygastridae described by Arnold Förster (1856), most of which represent distinct and recognizable lineages. The study provides their taxonomic history, diagnostic remarks, English translations, and illustrations of important specimens from the Förster collection in the Natural History Museum Vienna. The collection also includes original exemplar specimens of European species whose types have been lost. Potential neotypes and lectotypes from this material are noted, with the aim of improving nomenclatural stability in the group. Potential neotypes were found for Amblyaspis forticornis (Nees, 1834), Isocybus grandis (Nees, 1834), Platygaster striolata Nees, 1834, and Trichacis tristis (Nees, 1834). Lectotypes will be designated for Platygaster spinigera Nees, 1834, which will be transferred to Leptacis, and for Platygaster corvina Förster, 1861, with Platygaster henkvlugi Buhl, 1996 treated as a junior synonym. Synopeas mutica (Nees, 1834) should be transferred back to Platygaster. The second chapter addresses generic concepts within Platygastrinae sensu Ashmead. Part of Platygastrinae (former Inostemmatinae sensu Ashmead) was reviewed and keyed by Masner & Huggert (1989). However, more than half of the genera in the subfamily, including the vast majority of species, have not been revised. A working key to 14 major world genera, the first of its kind, is provided. An additional six genera and three subgenera of uncertain placement are discussed. The third chapter focuses on nomenclatural problems in the genus Platygaster Latreille, which is the type genus for its subfamily, family, and superfamily. It is also the largest genus in Platygastroidea with nearly 700 species, and recent evidence indicates that it is not monophyletic. It is necessary to establish the identity of the type specimen, as well as the identities of the 13 generic junior synonyms and four subgenera, in order to proceed with taxonomic divisions. The type specimen Scelio ruficornis Latreille, 1805, lost to science for 192 years, was rediscovered. However, it does not belong to the prevailing concept of Platygaster, but to Isocybus Förster, which has extreme taxonomic ramifications. The proposed solution would replace the type species of each genus in order to retain prevailing usage and prevent widespread confusion. A petition is presented to designate Epimeces ensifer Westwood as the type of Platygaster and Scelio ruficornis as the type of Isocybus. In the fourth chapter, the genus Trichacis Förster is revised for Europe. Examination of historical and modern collections combined with DNA barcoding revealed the presence of only a single species in Europe, Trichacis tristis (Nees, 1834), redescribed here. The results suggest that T. tristis has 14 junior synonyms: T. abdominalis (Thomson, 1859); T. bidentiscutum Szabó, 1981; T. didas (Walker, 1835); T. fusciala Szabó, 1981; T. hajduica Szabó, 1981; T. illusor Kieffer, 1916; T. nosferatus Buhl, 1997; T. pisis (Walker, 1835); T. persicus Asadi & Buhl, 2021; T. pulchricornis Szelényi, 1953; T. quadriclava Szabó, 1981; T. remulus (Walker, 1835); T. vitreus Buhl, 1997; and T. weiperti Buhl, 2019. Four species should be transferred to Amblyaspis Förster: T. afurcata Szabó, 1977, T. hungarica Szabó, 1977, T. pannonica Szabó, 1977, and T. tatika Szabó, 1977. Intraspecific variation, biological associations, and taxonomic history are discussed. DNA barcodes are provided and analyzed in the context of worldwide Trichacis and its sister genus Isocybus Förster. The fifth chapter examines platygastrid diversity in Germany in the context of insect decline. DNA barcodes indicate the presence of 178 observed species, with an estimated total of 290. GBOL sampling captured an estimated 93.7% of total species richness, but only 45.8% of rare species. A case study from Isocybus compares historical specimens, DNA barcode vouchers, and ecological data to illustrate the possible decline of a wetland parasitoid species. Altogether, the research demonstrates the importance of historical material, especially type specimens, in understanding biodiversity through time, and provides an essential taxonomic foundation for much-needed modern identification resources for Platygastrinae in the western Palearctic and beyond.
Interactions of farming and plant biodiversity in weed control related ecosystem service provision and weed conservation
(2020) Schumacher, Matthias; Gerhards, Roland
There is evidence that diverse plant communities in terrestrial ecosystems are either more stable or more productive in terms of food web support and ecosystem service provision. In agro-ecosystems, characterized by high disturbance and external inputs, plant diversity and their services can only be provided by weeds. In the first study, vegetation recordings and farmer surveys were conducted in on-farm experiments in two regions of Southwestern Germany. The aim was to examine the effects of agricultural management on weed community composition, weed biodiversity and occurrence of rare arable weed species in cereal fields. Weed biodiversity was influenced mainly by crop species, herbicide use and farming system as well as nitrogen and light availability. Weed communities were quite similar in both study regions and dominated by Alopecurus myosuroides, Galium aparine, Viola arvensis, Polygonum convolvulus and Veronica persica. A redundancy analysis revealed that the weed community was mainly shaped by crop species, tillage, location in the field and timing of herbicide application. The results highlight the erosion of weed communities due to intensive agricultural practices and emphasize the conservation of weed biodiversity per se and rare arable weed species in particular. The next aim was to examine if this biodiversity is able to support weed control related ecosystem services, like the predation of weed seeds. The objectives of this study were to investigate the connection between weed biodiversity, Carabid beetle diversity and weed seed predation as well to evaluate the role of farming intensity in this sequence. For this purpose, on-farm experiments were performed on the Eastern Swabian Alb. A positive correlation between weed biodiversity and Carabid beetle diversity was identified as well as a pattern of medium Carabid beetle diversity providing the highest weed seed predation. There was no consistent influence of farming intensity on weed seed predation. The revealed connection between weed diversity, Carabid beetle diversity and weed seed predation highlights the role of plants in food web support and subsequent ecosystem service provision. The utilization of these services depends on the promotion of biodiversity by designing appropriate management strategies. In the next step, the general principles underlying ecosystem service provision by biodiversity, were conveyed to a cover cropping system. The aim was to test single sown cover crops and species mixtures in terms of weed suppression efficacy and reliability. For this purpose, cover crop species were sown singly and as mixtures in a field experiment. Lower weed dry matter and weed densities were found predominantly in treatments with favorable establishment and above-average biomass production. Mixtures performed much more homogeneous in regard to the measured parameters compared to single sown cover crops. The results suggest that, although particular single sown cover crops are more effective to control weeds than mixtures, mixtures are more reliable under changing conditions. Altering the species composition of cover crop mixtures according to more complementary traits might further improve their weed control efficacy. The results of this dissertation demonstrate the importance of plant biodiversity in the provision and reliability of weed control related ecosystem services, either by weeds themselves or by specifically designed cover crop mixtures. Furthermore, management factors influencing weed biodiversity were determined, which can aid in the creation of more sustainable management strategies for a diverse agroecosystem and the conservation of rare arable weed species.
Peru Botanische Exkursion 2008
(2010) Dinter, Ina; Zimmermann, Reiner
The botanical excursion to Peru, a global hotspot of biodiversity, provides an overview of the climatic, regional and plant ecological situation of the equatorial neotropics. The areas visited cover the hyper arid coastal deserts, the dry and cold andine Puna, the Amazon lowland rainforests and the seasonal dry forests of North Peru. The excursion report presented was compiled from presentations and protocols of the participants and contains the list of plants found at each site visited.
Untersuchungen zur räumlichen Heterogenität von Kronenstruktur und Bestandesniederschlag in einem tropischen Bergregenwald
(2008) Oesker, Mathias; Küppers, Manfred
The objective of this study was to investigate the distribution and heterogeneity of canopy structure and precipitation throughfall and related with this the factors light, water, and nutrient input. Further to appraise the consequences of this heterogeneity as a factor, which forms ecological niches. The study took place in a tropical mountain rain forest in southern Ecuador, specifically in the Reserva San Francisco located north of the Podocarpus National Park. The area of research covered the altitudinal range from 1950 m a.s.l. to 2275 m a.s.l. Nine plots of 400 m2 (20 m by 20 m) were set up in three forest types, which differed in tree species composition (HOMEIER 2004). Two forest types were located on a ridge and one was in a gorge at the same elevation as the lower ridge forest type. In each forest type three representative plots were chosen and a total of 31 study points were defined. At each point throughfall was collected during a one-year period. In all throughfall samples the following parameters were determined: Volume, pH, electrical conductivity, concentration of K, Mg and Ca, nitrate, ammonium, organic nitrogen, phosphate, P, Mn, Cu, Rb, Sr and Pb. The canopy structure was determined at all points with both structural measurements and hemispherical photography over a period of three years. Lab experiments with a representative selection of tree species were performed in order to determine leaf surface water storage capacity and nutrient leaching out of leaves. For determination of canopy structure hemispherical photography turned out to be a particularly efficient method. The software HemiView (DeltaT) was used to calculate important information such as canopy openness, light environment and LAI. A high spatial heterogeneity with a coefficient of variation (CV) of 59 % was found for all parameters. It was higher than the temporal variability over three years (CV 12 %). The throughfall was most heterogeneous within the investigated parameter with a CV of 64 %. In total close to 82 % (between 0.5 % and 492 % and a CV 29 %) of the volume of the incident precipitation could be collected as throughfall in the forest. With this throughfall 49.1 kg ha-1 a-1 K, 3.7 kg ha-1 a-1 Mg and 8.7 kg ha-1 a-1 Ca (mean values) were transported. During low intensity rain events the proportion of throughfall, expressed as percentage of incident throughfall was significantly lower than the annual mean of the incident precipitation. For high rain intensities no differences were found. With a geostatistical approach to investigate the spatial distribution of the throughfall no clear results could be calculated because the three replicates diverged strongly from each other. Canopy structure and its species composition was influenced by the distribution of throughfall. Related to the amount of throughfall it could be shown that with an open canopy up to 100 % of the incident precipitation could be collected. Underneath a closed canopy, in average less throughfall was collected. However, the volume of throughfall showed high spatial distribution and heterogeneity with even more than 100 % of incident precipitation. Nevertheless, throughfall volume can be predicted using the parameters radiation and canopy openness at a zenith angle of 36°. Average water storage capacity of leaf surfaces from eleven most common tree species resulted in 74.74 ml m-2 leaf area. In a dry canopy with a theoretical equal distribution of precipitation and a given LAI this value equals 0.38 mm of rain. The nutrient leaching out of leaves is species dependent and differs statistically. Those lab results can be extrapolated to the entire forest: Including the water storage capacity and the number of rain events, a maximum leaching capacity of 220 kg ha-1 a-1 K, 14 kg ha-1 a-1 Mg and 67 kg ha-1 a-1 Ca can be calculated. The main focus of this study was to investigate heterogeneity of abiotic factors and its ecological consequences. In the forest type with the most heterogeneous canopy structure and the most heterogeneous distribution of throughfall amounts were found. Lowest heterogeneity of spatial distribution of throughfall element contents was found in forest type with the lowest tree species diversity. The higher the tree species diversity the more heterogeneously scattered is the element content in the throughfall.
Zur Diversität von Galium aparine L.-Herkünften
(2003) Ernst, Vera; Hurle, Karl
G. aparine is known as a very adaptable and worldwide distributed plant species. It is one of the worst weed species in numerous crops causing severe problems. Occasionally, a high degree of variability of G. aparine regarding to morphological and phenological characteristics was reported as well as to its herbicide susceptibility. Because of these observations and the necessity to gain more information about the biology and ecology of this species to perform a successful control of this weed in the field the variability of G. aparine was investigated. In comparative studies 24 field populations of different origins within Europe were used. For some of these populations the history of field management for the last few years was known. Additionally to the field populations one population from a hedgerow and one population of G. spurium has been further characterized. One central aim of these studies was the determination of the susceptibility of the populations against different herbicides. Furthermore the morphology and phenology of the different populations were also characterized. The variability of selected populations was examined by RAPD-PCR, too. The results of herbicide susceptibility tests showed that field populations of G. aparine reacted differently to the various herbicides. The largest differences in susceptibility were observed for the test herbicide, where one population showed a 6,8-fold higher tolerance than the most susceptible population (ED90). Low variability was detected for Mecoprop-P and Cinidon-ethyl, where populations differed at a factor of at most 1,5 and 1,7, respectively. Nearly all populations could be controlled with reduced herbicide concentrations compared to the recommended dosages. No resistant population was observed. Further, no significant differences between field populations and the hedgerow population could be detected. In several experiments the population of G. spurium tended to react slightly more susceptible towards the herbicides than G. aparine. A correlation between herbicide susceptibility and chemical control measures as described in the field history of the few past years could not be observed. The results with the test herbicide and Cinidon-ethyl might be interpreted as natural variability, because the active agents have not been on the market before sampling of the plants. Populations from adjacent fields showed as different susceptibilities as populations from distant fields, so that no regions with populations predominantly expressing significant levels of susceptibility or tolerance could be identified. The morphological and phenological tests showed that all populations differed regarding to many parameters. For most parameters the differences between the populations were in an identical range and persistently the populations differed at a maximum factor of 1,2-1,5. Higher differences than at this scale could be observed for the size of cotyledons, the number of seeds and the seminal yield. For the last parameter the largest differences could be observed with a maximum factor of 2,4 between the population with the smallest and highest seminal yield. Further, some populations showed a stronger habit than others. In a cluster analysis the G. aparine populations were divided into four groups. There was no difference between the field populations and the hedgerow population, but the population of G. spurium was, as expected, clearly different from G. aparine. An analysis of correlation revealed correlations for several parameters. For example, an early beginning of flowering was accompanied by a higher seminal yield. Some characteristics could furthermore be correlated with the geographic origin of the populations. Populations from northern and western locations often tended to have a less stronger habit than populations from the southern regions. Furthermore the onset of flowering was delayed compared to the populations from the more southern regions. The different characteristics could not been explained with the field history of the populations. Certainly the field history as well as climatic and geographic factors may have influenced the different morphology and phenology of the populations. In summary no morphological and phenological differences were detected between more sensitive or less sensitive populations. The results of the RAPD-PCR showed that 17 out of 40 tested primers were suitable to indicate polymorphisms between the different populations. They have been used to calculate the genetic similarity of the populations. The resulting genetic similarity of the G. aparine populations including the hedgerow population was between 93 and 97 %. G. spurium differed clearly from Galium aparine. No correlations could be detected between the results of the molecular and the morphological, phenological and herbicide susceptibility tests.