182 research outputs found
Mapping Invasive Giant Goldenrod (Solidago gigantea) with Multispectral Images Acquired by Unmanned Aerial Vehicle
Invasive alien species are one of the main threats to worldwide biodiversity loss. Unmanned aerial vehicles with multispectral sensors offer a cost-effective alternative to monitor invasive plant species at a centimetre scale. Giant Goldenrod (Solidago gigantea) is one of the most problematic invasive alien plant species in Switzerland and controlling this species – especially in nature protection areas – is a priority. In this study, a methodology is developed to detect the Giant Goldenrod coverage via unmanned aerial vehicle (UAV) equipped with multispectral sensors. Very high resolution maps (6.5 cm) are produced and high accuracy is achieved for the classification of the Giant Goldenrod coverage with a kappa coefficient of 0.902 and an overall accuracy of 92.12%. These results indicate that UAV equipped with multispectral sensors is a valuable tool in monitoring and combatting invasive alien species
Small-scale experimental habitat fragmentation reduces colonization rates in species-rich grasslands
Habitat fragmentation is one of the most important threats to biodiversity. Decreasing patch size may lead to a reduction in the size of populations and to an increased extinction risk of remnant populations. Furthermore, colonization rates may be reduced in isolated patches. To investigate the effects of isolation and patch size on extinction and colonization rates of plant species, calcareous grasslands at three sites in the Swiss Jura Mountains were experimentally fragmented into patches of 0.25, 2.25, and 20.25m2 by frequent mowing of the surrounding area from 1993 to 1999. Species richness in the fragment plots and adjacent control plots of the same sizes was recorded during these 7years. In agreement with the theory of island biogeography, colonization rate was reduced by 30% in fragments versus non-isolated controls, and extinction increased in small versus large plots. Habitat specialists, in contrast to generalists, were less likely to invade fragments. In the last 4years of the experiment, extinction rates tended to be higher in fragment than in control plots at two of the three sites. Despite reduced colonization rates and a tendency of increased extinction rates in fragments, fragmented plots had only marginally fewer species than control plots after 7years. Hence, rates were a more sensitive measure for community change than changes in species richness per se. From a conservation point of view, the detected reduced colonization rates are particularly problematic in small fragments, which are more likely to suffer from high extinction rates in the long ru
Nepal earthquake 2015: experience of junior clinical year medical students of Patan Academy of Health Sciences
Dilemmas regarding whether medical students’ participation ‘as doctor’ in disaster response is ethical remains unanswered. Although they prove to be an important addition to the workforce during such settings, their limited competency and likeliness to harm themselves and the patients in the process raises questions. Here we present our views on medical students’ involvement in disaster response based on our experiences at Patan Hospital, Patan Academy of Health Sciences (PAHS) during the Nepal earthquake 2015. Medical students play a crucial role in disaster management; however, they are not proficient in care for mass disasters. Nonetheless, being involved offered students first-hand experience on disaster response and also helped the disaster response by providing extra manpower. With more training, medical students can serve as a skillful workforce during disaster. The impact of regular drills strategically placed during medical school training in the curricula can be of immense help to build capacity for medical disaster response. Keywords: disaster response, mass disasters, medical students, Nepal earthquake 201
Definition of Core Bacterial Taxa in Different Root Compartments of Dactylis glomerata, Grown in Soil under Different Levels of Land Use Intensity
Plant-associated bacterial assemblages are critical for plant fitness. Thus, identifying a consistent plant-associated core microbiome is important for predicting community responses to environmental changes. Our target was to identify the core bacterial microbiome of orchard grass Dactylis glomerata L. and to assess the part that is most sensitive to land management. Dactylis glomerata L. samples were collected from grassland sites with contrasting land use intensities but comparable soil properties at three different timepoints. To assess the plant-associated bacterial community structure in the compartments rhizosphere, bulk soil and endosphere, a molecular barcoding approach based on high throughput 16S rRNA amplicon sequencing was used. A distinct composition of plant-associated core bacterial communities independent of land use intensity was identified. Pseudomonas, Rhizobium and Bradyrhizobium were ubiquitously found in the root bacterial core microbiome. In the rhizosphere, the majority of assigned genera were Rhodoplanes, Methylibium, Kaistobacter and Bradyrhizobium. Due to the frequent occurrence of plant-promoting abilities in the genera found in the plant-associated core bacterial communities, our study helps to identify “healthy” plant-associated bacterial core communities. The variable part of the plant-associated microbiome, represented by the fluctuation of taxa at the different sampling timepoints, was increased under low land use intensity. This higher compositional variation in samples from plots with low land use intensity indicates a more selective recruitment of bacteria with traits required at different timepoints of plant development compared to samples from plots with high land use intensity
Biodiversity maintains soil multifunctionality and soil organic carbon in novel urban ecosystems
1. Biodiversity in urban ecosystems has the potential to increase ecosystem functions and support a suite of services valued by society, including services provided by soils. Specifically, the sequestration of carbon in soils has often been advocated as a solution to mitigate the steady increase in CO2 concentration in the atmosphere as a key driver of climate change. However, urban ecosystems are also characterized by an often high level of ecological novelty due to profound human‐mediated changes, such as the presence of high numbers of non‐native species, impervious surfaces or other disturbances. Yet it is poorly understood whether and how biodiversity affects ecosystem functioning and services of urban soils under these novel conditions.
2. In this study, we assessed the influence of above‐ and below‐ground diversity, as well as urbanization and plant invasions, on multifunctionality and organic carbon stocks of soils in non‐manipulated grasslands along an urbanization gradient in Berlin, Germany. We focused on plant diversity (measured as species richness and functional trait diversity) and, in addition, on soil organism diversity as a potential mediator for the relationship of plant species diversity and ecosystem functioning.
3. Our results showed positive effects of plant diversity on soil multifunctionality and soil organic carbon stocks along the entire gradient. Structural equation models revealed that plant diversity enhanced soil multifunctionality and soil organic carbon by increasing the diversity of below‐ground organisms. These positive effects of plant diversity on soil multifunctionality and soil fauna were not restricted to native plant species only, but were also exerted by non‐native species, although to a lesser degree.
4. Synthesis. We conclude that enhancing diversity in plants and soil fauna of urban grasslands can increase the multifunctionality of urban soils and also add to their often underestimated but very valuable role in mitigating effects of climate change
The Influence of Land Use Intensity on the Plant-Associated Microbiome of Dactylis glomerata L.
In this study, we investigated the impact of different land use intensities
(LUI) on the root-associated microbiome of Dactylis glomerata (orchardgrass).
For this purpose, eight sampling sites with different land use intensity
levels but comparable soil properties were selected in the southwest of
Germany. Experimental plots covered land use levels from natural grassland up
to intensively managed meadows. We used 16S rRNA gene based barcoding to
assess the plant-associated community structure in the endosphere, rhizosphere
and bulk soil of D. glomerata. Samples were taken at the reproductive stage of
the plant in early summer. Our data indicated that roots harbor a distinct
bacterial community, which clearly differed from the microbiome of the
rhizosphere and bulk soil. Our results revealed Pseudomonadaceae,
Enterobacteriaceae and Comamonadaceae as the most abundant endophytes
independently of land use intensity. Rhizosphere and bulk soil were dominated
also by Proteobacteria, but the most abundant families differed from those
obtained from root samples. In the soil, the effect of land use intensity was
more pronounced compared to root endophytes leading to a clearly distinct
pattern of bacterial communities under different LUI from rhizosphere and bulk
soil vs. endophytes. Overall, a change of community structure on the
plant–soil interface was observed, as the number of shared OTUs between all
three compartments investigated increased with decreasing land use intensity.
Thus, our findings suggest a stronger interaction of the plant with its
surrounding soil under low land use intensity. Furthermore, the amount and
quality of available nitrogen was identified as a major driver for shifts in
the microbiome structure in all compartments
A multidimensional framework for measuring biotic novelty: How novel is a community?
Anthropogenic changes in climate, land use, and disturbance regimes, as well as introductions of non‐native species can lead to the transformation of many ecosystems. The resulting novel ecosystems are usually characterized by species assemblages that have not occurred previously in a given area. Quantifying the ecological novelty of communities (i.e., biotic novelty) would enhance the understanding of environmental change. However, quantification remains challenging since current novelty metrics, such as the number and/or proportion of non‐native species in a community, fall short of considering both functional and evolutionary aspects of biotic novelty. Here, we propose the Biotic Novelty Index (BNI), an intuitive and flexible multidimensional measure that combines (a) functional differences between native and non‐native introduced species with (b) temporal dynamics of species introductions. We show that the BNI is an additive partition of Rao's quadratic entropy, capturing the novel interaction component of the community's functional diversity. Simulations show that the index varies predictably with the relative amount of functional novelty added by recently arrived species, and they illustrate the need to provide an additional standardized version of the index. We present a detailed R code and two applications of the BNI by (a) measuring changes of biotic novelty of dry grassland plant communities along an urbanization gradient in a metropolitan region and (b) determining the biotic novelty of plant species assemblages at a national scale. The results illustrate the applicability of the index across scales and its flexibility in the use of data of different quality. Both case studies revealed strong connections between biotic novelty and increasing urbanization, a measure of abiotic novelty. We conclude that the BNI framework may help building a basis for better understanding the ecological and evolutionary consequences of global change
Biodiversity research: data without theory—theory without data
Meet two famous researchers from the early days of biodiversity research: Charles Darwin and Alexander von Humboldt. Darwin developed a powerful theory, using a limited amount of data by modern standards. Humboldt, in contrast, compiled a “Cosmos” of data without developing a major theory, although some of Humboldt's observations on latitudinal biodiversity gradients (von Humboldt, 1808) were later used to develop theory. This tension between data and theory still persists today and is perhaps becoming more acute
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Biodiversity research: Data without theory-theory without data
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