Burning and mowing similarly increase prairie plant production in the spring, but not due to increased soil temperatures

Burning and mowing are two of the most common grassland disturbances across millions of hectares worldwide, but uncertainty remains about when and why these disturbances increase plant production. One of the main hypotheses for increased plant production is that disturbances increase soil temperature in the early growing season and thereby increase plant growth. I tested this hypothesis using a multi‐decade study of the frequency (annual or quadrennial) and season (spring, summer, or autumn) of reconstructed tallgrass prairie burning and mowing. To determine plant production, I measured aboveground biomass during three periods of the 2015 growing season: (1) prior to mid‐May; (2) mid‐May to early July; and (3) early July to the end of the growing season in late September. I also measured soil temperatures from May 2014 to January 2016. This unique dataset allows a detailed picture of when burning and mowing are increasing plant production and whether these increases are likely caused by soil temperatures. I found that, compared to other treatments, autumn burning and mowing similarly increased plant production from the beginning of the growing season to mid‐May (autumn disturbances increased production from 37 to 77 g/m2) and, compared to other treatments, both autumn and spring burning and mowing similarly increased plant production from mid‐May to early July (autumn and spring disturbances increased production from 363 to 439 g/m2). Mowing had little effect on soil temperature but burning increased average daily maximum soil temperature at 2.5 cm depth by 6.4°C in the month after burning. Overall, these results suggest that burning did not increase early growing season plant production due to increased soil temperature, given that mowing similarly affected plant production but did not similarly affect soil temperature. I explore alternate explanations for changes in plant production, including increased light and nutrient availability, and decreased detritus

GRASSLAND DIVERSITY AND PRODUCTIVITY: THE INTERPLAY OF RESOURCE AVAILABILITY AND PROPAGULE POOLS

Processes operating at multiple spatial scales govern the structure and functioning of ecological communities. We conducted a resource manipulation and propagule addition experiment in grassland to evaluate the interaction of local resource availability and propagule pools in governing local-scale plant colonization, biodiversity, and above-ground productivity. The availabilities of establishment microsites and water were manipulated in field plots for two years through the application of experimental soil disturbances and irrigation, respectively. Resource manipulations led to increased invasibility of the community, as predicted by the theory of fluctuating resources. Rates of colonization,enhanced by the sowing of 32 grassland species, increased plant diversity and above ground productivity, but to a greater extent under conditions of resource enrichment. Although resource enrichment generally increased diversity and productivity, these responses were contingent upon species availability and tended to be more pronounced in the presence of an expanded propagule pool. These findings suggest that biodiversity at the level of the available propagule pool and fluctuations in resources interact to regulate local resident diversity and productivity by determining opportunities for species sorting, by mediating community assembly, and by governing the potential for functional compensation in the community

Can the Results of Biodiversity-Ecosystem Productivity Studies Be Translated to Bioenergy Production?

Biodiversity experiments show that increases in plant diversity can lead to greater biomass production, and some researchers suggest that high diversity plantings should be used for bioenergy production. However, many methods used in past biodiversity experiments are impractical for bioenergy plantings. For example, biodiversity experiments often use intensive management such as hand weeding to maintain low diversity plantings and exclude unplanted species, but this would not be done for bioenergy plantings. Also, biodiversity experiments generally use high seeding densities that would be too expensive for bioenergy plantings. Here we report the effects of biodiversity on biomass production from two studies of more realistic bioenergy crop plantings in southern Michigan, USA. One study involved comparing production between switchgrass (Panicum virgatum) monocultures and species-rich prairie plantings on private farm fields that were managed similarly to bioenergy plantings. The other study was an experiment where switchgrass was planted in monoculture and in combination with increasingly species-rich native prairie mixtures. Overall, we found that bioenergy plantings with higher species richness did not produce more biomass than switchgrass monocultures. The lack of a positive relationship between planted species richness and production in our studies may be due to several factors. Non-planted species (weeds) were not removed from our studies and these non-planted species may have competed with planted species and also prevented realized species richness from equaling planted species richness. Also, we found that low seeding density of individual species limited the biomass production of these individual species. Production in future bioenergy plantings with high species richness may be increased by using a high density of inexpensive seed from switchgrass and other highly productive species, and future efforts to translate the results of biodiversity experiments to bioenergy plantings should consider the role of seeding density

Grassland diversity and productivity: the interplay of resource availability and propagule pools

Processes operating at multiple spatial scales govern the structure and functioning of ecological communities. We conducted a resource manipulation and propagule addition experiment in grassland to evaluate the interaction of local resource availability and propagule pools in governing local-scale plant colonization, biodiversity, and aboveground productivity. The availabilities of establishment microsites and water were manipulated in field plots for two years through the application of experimental soil disturbances and irrigation, respectively. Resource manipulations led to increased invasibility of the community, as predicted by the theory of fluctuating resources. Rates of colonization, enhanced by the sowing of 32 grassland species, increased plant diversity and aboveground productivity, but to a greater extent under conditions of resource enrichment. Although resource enrichment generally increased diversity and productivity, these responses were contingent upon species availability and tended to be more pronounced in the presence of an expanded propagule pool. These findings suggest that biodiversity at the level of the available propagule pool and fluctuations in resources interact to regulate local resident diversity and productivity by determining opportunities for species sorting, by mediating community assembly, and by governing the potential for functional compensation in the community

Height and clonality traits determine plant community responses to fertilization

Fertilization via agricultural inputs and nutrient deposition is one of the major threats to global terrestrial plant richness, yet we still do not fully understand the mechanisms by which fertilization decreases plant richness. Tall clonal species have recently been proposed to cause declines in plant species richness by increasing in abundance in response to fertilization and competing strongly with other species. We tested this hypothesis in a fertilization experiment in a low productivity grassland by using a novel experimental manipulation of the presence vs. absence of clonal species and by examining the role of height within these treatments. We found that fertilization decreased species richness more in the presence than absence of clonal species. We also found that only tall species increased in biomass in response to fertilization. In the absence of clonal species, fertilization increased biomass of tall non clonal species. However, in the presence of clonal species, fertilization decreased tall non clonal biomass and only tall clonal biomass increased. Fertilization caused almost all short species to be lost in the presence, but not the absence, of clonal species and caused greater declines in the mean and variance of light levels in the presence of clonal species. These results show that the traits of species in a community can determine the magnitude of species loss due to fertilization. The strongly negative effect of tall clonals on species richness in fertilized plots is likely a result of their capacity to decrease light levels to a greater extent and more uniformly than non clonal species, and thereby drive the exclusion of short species. These results help clarify the mechanisms whereby fertilization decreases grassland plant species richness and suggest that efforts to prevent the loss of species under fertilized conditions may be most effective when they focus on controlling the biomass of tall clonal species

A metatranscriptomic approach to explore longitudinal tissue specimens from non-healing diabetes related foot ulcers

Cellular mechanisms and/or microbiological interactions which contribute to chronic diabetes related foot ulcers (DRFUs) were explored using serially collected tissue specimens from chronic DRFUs and control healthy foot skin. Total RNA was isolated for next-generation sequencing. We found differentially expressed genes (DEGs) and enriched hallmark gene ontology biological processes upregulated in chronic DRFUs which primarily functioned in the host immune response including: (i) Inflammatory response; (ii) TNF signalling via NFKB; (iii) IL6 JAK-STAT3 signalling; (iv) IL2 STAT5 signalling and (v) Reactive oxygen species. A temporal analysis identified RN7SL1 signal recognition protein and IGHG4 immunoglobulin protein coding genes as being the most upregulated genes after the onset of treatment. Testing relative temporal changes between healing and non-healing DRFUs identified progressive upregulation in healed wounds of CXCR5 and MS4A1 (CD20), both canonical markers of lymphocytes (follicular B cells/follicular T helper cells and B cells, respectively). Collectively, our RNA-seq data provides insights into chronic DRFU pathogenesis

Perennial grasslands enhance biodiversity and multiple ecosystem services in bioenergy landscapes

Agriculture is being challenged to provide food, and increasingly fuel, for an expanding global population. Producing bioenergy crops on marginal lands—farmland suboptimal for food crops—could help meet energy goals while minimizing competition with food production. However, the ecological costs and benefits of growing bioenergy feedstocks—primarily annual grain crops—on marginal lands have been questioned. Here we show that perennial bioenergy crops provide an alternative to annual grains that increases biodiversity of multiple taxa and sustain a variety of ecosystem functions, promoting the creation of multifunctional agricultural landscapes. We found that switchgrass and prairie plantings harbored significantly greater plant, methanotrophic bacteria, arthropod, and bird diversity than maize. Although biomass production was greater in maize, all other ecosystem services, including methane consumption, pest suppression, pollination, and conservation of grassland birds, were higher in perennial grasslands. Moreover, we found that the linkage between biodiversity and ecosystem services is dependent not only on the choice of bioenergy crop but also on its location relative to other habitats, with local landscape context as important as crop choice in determining provision of some services. Our study suggests that bioenergy policy that supports coordinated land use can diversify agricultural landscapes and sustain multiple critical ecosystem services

A real-time ppg peak detection method for accurate determination of heart rate during sinus rhythm and cardiac arrhythmia

Objective: We have developed a peak detection algorithm for accurate determination of heart rate, using photoplethysmographic (PPG) signals from a smartwatch, even in the presence of various cardiac rhythms, including normal sinus rhythm (NSR), premature atrial contraction (PAC), premature ventricle contraction (PVC), and atrial fibrillation (AF). Given the clinical need for accurate heart rate estimation in patients with AF, we developed a novel approach that reduces heart rate estimation errors when compared to peak detection algorithms designed for NSR. Methods: Our peak detection method is composed of a sequential series of algorithms that are combined to discriminate the various arrhythmias described above. Moreover, a novel Poincaré plot scheme is used to discriminate between basal heart rate AF and rapid ventricular response (RVR) AF, and to differentiate PAC/PVC from NSR and AF. Training of the algorithm was performed only with Samsung Simband smartwatch data, whereas independent testing data which had more samples than did the training data were obtained from Samsung’s Gear S3 and Galaxy Watch 3. Results: The new PPG peak detection algorithm provides significantly lower average heart rate and interbeat interval beat-to-beat estimation errors—30% and 66% lower—and mean heart rate and mean interbeat interval estimation errors—60% and 77% lower—when compared to the best of the seven other traditional peak detection algorithms that are known to be accurate for NSR. Our new PPG peak detection algorithm was the overall best performers for other arrhythmias. Conclusion: The proposed method for PPG peak detection automatically detects and discriminates between various arrhythmias among different waveforms of PPG data, delivers significantly lower heart rate estimation errors for participants with AF, and reduces the number of false negative peaks. Significance: By enabling accurate determination of heart rate despite the presence of AF with rapid ventricular response or PAC/PVCs, we enable clinicians to make more accurate recommendations for heart rate control from PPG data

Different paths to the modern state in Europe: the interaction between domestic political economy and interstate competition

Theoretical work on state formation and capacity has focused mostly on early modern Europe and on the experience of western European states during this period. While a number of European states monopolized domestic tax collection and achieved gains in state capacity during the early modern era, for others revenues stagnated or even declined, and these variations motivated alternative hypotheses for determinants of fiscal and state capacity. In this study we test the basic hypotheses in the existing literature making use of the large date set we have compiled for all of the leading states across the continent. We find strong empirical support for two prevailing threads in the literature, arguing respectively that interstate wars and changes in economic structure towards an urbanized economy had positive fiscal impact. Regarding the main point of contention in the theoretical literature, whether it was representative or authoritarian political regimes that facilitated the gains in fiscal capacity, we do not find conclusive evidence that one performed better than the other. Instead, the empirical evidence we have gathered lends supports to the hypothesis that when under pressure of war, the fiscal performance of representative regimes was better in the more urbanized-commercial economies and the fiscal performance of authoritarian regimes was better in rural-agrarian economie

Hundreds of variants clustered in genomic loci and biological pathways affect human height

Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P < 0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.