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9,671 results for “Leaf”
Photosynthesis Leaf Chemistry:BioCON : Biodiversity, Elevated CO2, and N Enrichment
BioCON (Biodiversity, CO2, and Nitrogen) is an ecological experiment started in 1997 at the University of Minnesota's Cedar Creek Ecosystem Science Reserve. BioCON's goal is to explore the ways in which plant communities will respond to three environmental changes that are known to be occurring on a global scale: increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity. Why Biodiversity, CO2, and Nitrogen? While there are many uncertainties in global change biology, there are also some well documented facts. Some of these are: 1. The amount of carbon dioxide (CO2) in the atmosphere is rising. Since the industrial revolution, the CO2 concentration in the atmosphere has increased from approximately 275 parts per million (ppm) to about 378 ppm today. This has been largely the result of fossil fuel burning. It is expected that CO2 levels will continue to rise, and that by the year 2050 these levels will be approximately 550 ppm. CO2 is the raw material for photosynthesis and is known to affect plant growth and development. 2. The amount of nitrogen moving through terrestrial ecosystems has increased in the recent past. While natural "background" levels of nitrogen fixation have remained constant, human additions to the system through fertilizer production and fossil fuel use have increased dramatically. Nitrogen is a key nutrient for plant growth and plays a critical role in plant community structure and composition in many environments. 3. Biodiversity levels are falling. While the research and data are not as complete as they are for CO2 and nitrogen, data indicate that the number of species globally, is being reduced. Perhaps more important for ecosystem function, diversity levels on local to regional scales have fallen due to land use change, biotic invasion and many other drivers. While much is known about how each of these factors affects ecosystem functioning, many questions remain. There is also little data on how these issues affe
Seasonal leaf litter mass (2000 - 2010) for the Functional Diversity project, Coweeta Hydrologic Laboratory, Otto, North Carolina
The importance of the herbaceous layer in regulating ecosystem processes in deciduous forests is generally unknown. We use a manipulative study in a rich, mesophytic cove forest in the southern Appalachians to test the following hypotheses: (i) the herbaceous functional group (HFG) in mesophytic coves accelerates carbon and nutrient cycling, (ii) high litter quality input and rapid nutrient turnover associated with HFG will have a positive effect on overstory tree growth, and (iii) the HFG regulates tree regeneration with negative effects on seedling establishment due to competition for resources. We established treatment plots in a mesic, cove-hardwoods forest and removed the herbaceous flora (HR, removed twice per year) or added herbaceous organic material (OMA, once per year) for comparison to a no removal (NR) reference for a total of 14 years. The OMA treatment stimulated soil N-mineralization and increased litterfall mass and N content. OMA N-mineralization rates were more than two times greater than both the NR and HR treatments; however, we did not detect significant differences in soil CO2 efflux among treatments. Higher overstory litterfall mass and N in the OMA treatment plots indicated that overstory trees were benefiting from the enhanced soil N-mineralization. Higher overstory leaf mass and N suggests an important linkage between HR and aboveground net primary production even though this did not translate into greater tree basal area increment. We found an increase in regeneration of all tree species with HFG removal, and the response was particularly evident for Acer rubrum seedlings.
The importance of crayfish in the breakdown of rhododendron leaf litter at the Coweeta Hydrologic Laboratory in 1999
Rhododendron (Rhododendron maximum) is a common evergreen shrub in riparian areas of the southern Appalachians, where its leaves can comprise a large proportion of leaf litter in streams. However, they are relatively refractory and generally considered a low quality food resource for detritivores. Our objective was to assess whether macroconsumers (primarily crayfish (Cambarus bartonii)) influence rhododendron leaf breakdown in a forested southern Appalachian stream in both summer (when leaves other than rhododendron are relatively scarce) and autumn (when other leaves are relatively abundant). We conducted two leaf decay experiments, one in summer and one in autumn, using pre-conditioned leaves. Macroconsumers were excluded from the benthos of a fourth-order stream using electric fences; we predicted that excluding macroconsumers would reduce the decay rate of rhododendron leaves in both summer and autumn.
Leaf decomposition in relation to resource characteristics and consumer diversity
Resource subsidies and biodiversity are essential for maintaining community structure and ecosystem functioning, but the relative importance of consumer diversity and resource characteristics to decomposition remains unclear. Forested headwater streams are detritus-based systems, dependent on leaf litter inputs from adjacent riparian ecosystems, and decomposition of these resources is an important ecosystem function. Here, we examined the effects of consumer community diversity on leaf decomposition in a reciprocal transplant experiment. We asked: (1) if stream consumer communities are adapted to local resources, and (2) how functional trait diversity among communities affects the leaf decomposition process. We did not find evidence that communities were adapted to locally-derived resource subsidies. Instead, we found that consumer biomass and functional trait diversity as well as resource characteristics were the primary biotic drivers of decomposition. Consumer biomass was stimulated by specific resource subsidies, leading to direct and indirect effects of resource subsidies on ecosystem functioning. Contrary to current theory, we show that decomposition was higher with decreased detritivore functional diversity, suggesting dominant traits encompassing a specific niche increased decomposition. We also show that top-down, consumer diversity effects can be equal in magnitude to the bottom-up effects of resource characteristics during the decomposition process. Our research illustrates the importance of considering multiple biotic and abiotic drivers interacting via multiple pathways to affect a crucial ecosystem function.
Ground observations of spring leaf emergence phenology at eight sites in and near the Coweeta basin (2011-2012).
This study was conducted to evaluate the utility of satellite data from the MODIS sensor to predict the timing of spring leaf emergence in the Southern Appalachians. Eight ground sampling sites were established on square plots (231 x 231 meters) that corresponded to the dimensions of MODIS satellite pixels. Each site was visited approximately every other day and observations on the status of leaf emergence in the canopy and understory were collected at 30 subsampling points within each site. Observations consisted of visual estimates of leaf emergence status on marked trees and shrubs, as well as digital photographs of the canopy and understory taken from consistent locations at each subsampling point.
Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Forest: Leaf Level Photosynthesis
Leaf-level photosynthesis was measured on all Climate Change Across Seasons Experiment (CCASE) plots. Reference (or control) plots are shared with the collaborating Northern Forest DroughtNet experiment. There are six plots total (each 11 x 14m). Two are warmed 5 degrees C throughout the growing season (Plots 3 and 4). Two others are warmed 5 degrees C in the growing season and have snow removed during winter to induce soil freezing and then warming cables turn on to create thaws; each soil freeze/thaw cycle includes 72-hours of soil freezing followed by 72-hours of thaw (Plots 5 and 6). Four kilometers (2.5 mi) of heating cable are buried in the soil to warm these four plots. Two additional plots serve as controls for our experiment (Plots 1 and 2). This data set includes photosynthesis measurements for 2015 and 2017 growing seasons. These photosynthesis data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.
Hubbard Brook Experimental Forest Watershed 1 Temporal Canopy Leaf Chemistry, 1999 - 2002
Overstory foliage is collected in late summer from calcium-treated forest on watershed 1. Nutrient concentrations in foliage are measured. This allows us to estimate the pool of nutrients in foliage in combination with litterfall estimates of foliage biomass. We can compare foliar chemistry in W1 with that in W6 to quantify calcium treatment effects. Long-term measurements continue with the aim of detecting trends in foliage chemistry over long time scales. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.
Leaf area index following the ice storm of January 1998 at the Hubbard Brook Experimental Forest
This dataset includes measurements of changes in Leaf Area Index (LAI) collected as part of a long-term study of the recovery of the forest canopy following the ice storm of January 1998. Measurements were taken in Watershed 1 and Watershed 6 between July 1998 and July 2006. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.
Small Mammal Exclosure Study (SMES) Leaf Litter Study in the Chihuahuan Desert Grassland and Shrubland at the Sevilleta National Wildlife Refuge, New Mexico
The purpose of this study is to determine whether or not the activities of small mammals regulate plant community structure, plant species diversity, and spatial vegetation patterns in Chihuahuan Desert shrublands and grasslands. What role if any do indigenous small mammal consumers have in maintaining desertified landscapes in the Chihuahuan Desert? Additionally, how do the effects of small mammals interact with changing climate to affect vegetation patterns over time? This is data for cover of dead plant leaf litter accumulations on soil surfaces measured on each of the SMES study plots. Leaf litter cover was measured from each of the 36 one-meter2 quadrats twice each year when vegetation was measured.
SGS-LTER CO2 Elevation Study: Leaf carbon isotope, nitrogen, carbon and Ci/Ca means from the SGS Open Top Chamber experiment on the Central Plains Experimental Range, Nunn, Colorado, USA 1997 - 2001
This data package was produced by researchers working on the Shortgrass Steppe Long Term Ecological Research (SGS-LTER) Project, administered at Colorado State University. Long-term datasets and background information (proposals, reports, photographs, etc.) on the SGS-LTER project are contained in a comprehensive project collection within the Digital Collections of Colorado (http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429). The data table and associated metadata document, which is generated in Ecological Metadata Language, may be available through other repositories serving the ecological research community and represent components of the larger SGS-LTER project collection. Additional information and referenced materials can be found: http://hdl.handle.net/10217/82454. Carbon isotopes of elevated and ambient OTC plants were measured for use in isotope labeling and plant water-use-efficiency measures. Leaf N and C are associated parameters were also measured. This research was conducted at the Central Plains Experimental Range, near Nunn, CO; lat.40degrees 40 minutes N; long. 104 degrees 45 minutes W in the shortgrass steppe region of NE Colorado, USA and as a collaboration between SGS-LTER and USDA-ARS researchers.
Leaf area index (LAI), leaf traps and allometric data for Morella cerifera on Hog Island, VA 2004 and 2007
Leaf-area index (LAI) and understory light levels of Morella cerifera shrub thickets were assessed on Hog Island, Virginia, USA, at four sites along a soil chronosequence. LAI was estimated from annual leaf litter, with allometric models relating stem diameter to leaf area, with a portable integrating radiometer (LI-COR LAI-2000), and from photosynthetically active radiation (PAR) using the Beer-Lambert law. Read More: http://www.esajournals.org/doi/full/10.1890/06-0913
Data supporting "Leaf carbon and water status control stomatal and non-stomatal limitations of photosynthesis in trees."
<p>Data supporting our New Phytologist publication: "Leaf carbon and water status control stomatal and non-stomatal limitations of photosynthesis in trees"</p> <p> </p>
Data from: Heterosis of leaf and rhizosphere microbiomes in field-grown maize
<p>Data and code associated with the submitted manuscript "<strong>Heterosis of leaf and rhizosphere microbiomes in field-grown maize</strong>". Detailed descriptions of each file can be found in the README.txt . The raw sequence data associated with this work can be downloaded from the NCBI Sequence Read Archive, listed under BioProject #PRJNA597058.</p>
The transcription regulatory code of a plant leaf
<p>The transcription regulatory network underlying essential and complex functionalities inside a eukaryotic cell is defined by the combinatorial actions of transcription factors (TFs). However, TF binding studies in plants are too few in number to produce a general and comparative picture of this complex regulatory network. Here, we used ChIP-seq to determine the binding profiles of 104 TF expressed in the maize leaf (Data can be downloaded from NCBI SRA under accession number PRJNA518749) </p> <p>With this large dataset, we trained machine-learning models to identify TF sequence preferences. A contrast between Maize and Arabidopsis TF sequence preferences revealed that DNA binding follows the conservation of TF protein families. Finally, the trained models were used to predict and compare the regulatory networks in other grasses species (Sorghum and Rice), which revealed that the edges between TF and TF coding genes are more likely to be maintained (<em>i.e., </em>evolutionarily conserved). </p> <p>On a practical level, we expect the presented TF binding models to be integrated into pipelines to predict effects of non-coding variants, both common and rare, on TF binding, to pinpoint causal sites. As the possibility of being able to predict and generate novel variation not seen in nature could fundamentally change future plant breeding.</p> <p>Detail: Each *tar.gz file is a <strong><a href="https://bmcplantbiol.biomedcentral.com/articles/10.1186/s12870-019-1693-2">bag-of-k-mer model</a></strong> fitted for a single ZmTF, which can be used for predictions. Information about each ZmTF is included in the table tfids.tsv</p> <p>For more information about the project: <br> <a href="https://www.biorxiv.org/content/10.1101/2020.01.07.898056v3"><strong>The transcription regulatory code of a plant leaf</strong></a></p>
Data from: Genome assembly of the ragweed leaf beetle, a step forward to better predict rapid evolution of a weed biocontrol agent to environmental novelties
<p><span>Rapid evolution of weed biological control agents (BCAs) to new biotic and abiotic conditions is poorly understood and so far, only little considered both in pre-release and post-release studies, despite potential major negative or positive implications for risks of non-targeted attacks or for colonizing yet unsuitable habitats, respectively. Provision of genetic resources, such as assembled and annotated genomes, is essential to assess potential adaptive processes by identifying underlying genetic mechanisms. Here, we provide the first sequenced genome of a phytophagous insect used as a BCA, <i>i.e.</i> the leaf beetle <i>Ophraella communa</i>, a promising BCA of common ragweed, recently and accidentally introduced into Europe. A total 33.98 Gb of raw DNA sequences, representing c. 43-fold coverage, were obtained using the PacBio SMRT-Cell sequencing approach. Among the five different assemblers tested, the SMARTdenovo assembly displaying the best scores was then corrected with Illumina short reads. A final genome of 774 Mb containing 7,003 scaffolds was obtained. The reliability of the final assembly was then assessed by benchmarking universal single-copy orthologous genes (> 96.0% of the 1,658 expected insect genes) and by remapping tests of Illumina short reads (average of 98.6% ± 0.7% without filtering). The number of protein-coding genes of 75,642, representing 82% of the published antennal transcriptome, and the phylogenetic analyses based on 825 orthologous genes placing <i>O. communa </i>in the monophyletic group of Chrysomelidae, confirm the relevance of our genome assembly. Overall, the genome provides a valuable resource for studying potential risks and benefits of this BCA facing environmental novelties.</span></p>
Monthly GPP datasets for 2000-2017 in China from the big-leaf TEC model and the two-leaf DTEC model
<p>The monthly GPP datasets were calculated from MODIS LAI/FPAR products (MOD15A2, Version 6) and meteorological data for 2000-2017 in China at a resolution of 0.05 degree ×0.05 degree. The TwoLeaf-DTEC-GPP-5km data was derived from the Two-leaf-based DTEC GPP model. The BigLeaf-TEC-GPP-5km data was calculated from the Big-leaf-based TEC GPP model. The BigLeaf-TEC-GPP-5km-2000-2017.zip includes 19 separate GPP data files and each represents one year data including 12 monthly data.</p>
Data from: Leaf nutrients, not specific leaf area, are consistent indicators of elevated nutrient inputs
Leaf traits are frequently measured in ecology to provide a 'common currency' for predicting how anthropogenic pressures impact ecosystem function. Here, we test whether leaf traits consistently respond to experimental treatments across 27 globally distributed grassland sites across 4 continents. We find that specific leaf area (leaf area per unit mass)—a commonly measured morphological trait inferring shifts between plant growth strategies—did not respond to up to four years of soil nutrient additions. Leaf nitrogen, phosphorus and potassium concentrations increased in response to the addition of each respective soil nutrient. We found few significant changes in leaf traits when vertebrate herbivores were excluded in the short-term. Leaf nitrogen and potassium concentrations were positively correlated with species turnover, suggesting that interspecific trait variation was a significant predictor of leaf nitrogen and potassium, but not of leaf phosphorus concentration. Climatic conditions and pretreatment soil nutrient levels also accounted for significant amounts of variation in the leaf traits measured. Overall, we find that leaf morphological traits, such as specific leaf area, are not appropriate indicators of plant response to anthropogenic perturbations in grasslands.
Data from: Optimisation of biogenic synthesis of silver nanoparticles from flavonoid-rich Clinacanthus nutans leaf and stem aqueous extracts
<p>BACKGROUND: Silver nanoparticles (AgNPs) are widely used in food industries, biomedical, dentistry, catalysis, diagnostic biological probes, and sensors. The use of plant extract for AgNPs synthesis eliminates the process of maintaining cell culture and the process could be scaled up under a non-aseptic environment. The purpose of this study is to determine the classes of phytochemicals, to biosynthesise and characterise the AgNPs using Clinacanthus nutans leaf and stem extracts. In this study, AgNPs was synthesised from the aqueous extracts of C. nutans leaves and stems through a non-toxic, cost effective and eco-friendly method.</p> <p>RESULTS: The formation of AgNPs was confirmed by UV-Vis spectroscopy, and the size of AgNP-L (leaf) and AgNP-S (stem) were 114 and 129 nm, respectively. Transmission electron microscopy (TEM) analysis showed spherical nanoparticles with AgNP-L and AgNP-S ranging from 10-300 nm and 10-180 nm; with zeta potentials of AgNP-L and AgNP-S at -42.8 and -43.9 mV, respectively. XRD analysis matched the face-centred cubic structure of silver and was capped with bioactive compounds. FTIR analysis revealed the presence of few functional groups of phenolic and flavonoid compounds. These functional groups act as reducing agents in AgNPs synthesis.</p> <p>CONCLUSION: This result showed that the biogenically synthesised nanoparticles reduced silver ions to silver nanoparticles in aqueous condition and the AgNPs formed were stable and less toxic.</p>
Data from: Invertebrate phenology modulates the effect of the leaf economics spectrum on litter decomposition rate across 41 subtropical woody plant species
<ol> <li>Litter quality and decomposers are critical to carbon and nutrient cycling through litter decomposition. However, how relationships between litter quality and invertebrate detritivores change litter mass loss through time is poorly known. Species' initial leaf litter quality, as a legacy of their position on the "leaf economics spectrum" (LES), may determine the invertebrate contribution to litter mass loss. This contribution may change through time, as both population peaks of invertebrate detritivores and litter quality of given species will change through time.</li> <li>Here we introduce invertebrate phenology into a conceptual model of drivers of litter mass loss. We hypothesized that in the early decomposition period, LES can predict litter decomposability with or without a strong invertebrate contribution, i.e., litter with higher nutrient content would decompose faster. But in the later decomposition period, when higher quality litter will already have decomposed too much and lower quality litters have still been less degraded, a strong invertebrate peak would coincide with relatively more consumption of initially lower quality litters; this would lead to a hump-back relationship between leaf litter mass loss and initial LES position in this period.</li> <li>We tested our hypothesis through a one-year field decomposition experiment using leaf litter of 41 woody species in each of two sites in subtropical forest in China; only one of these sites had a strong late peak of leaf litter-feeding moth larvae in the litter layer.</li> <li>LES score of litter species had a positive linear relationship with litter mass loss before the key invertebrate consumer peaks in the litter layer. However, with the invertebrates peaking later into the decomposition process, the invertebrate consumption peaked at initially lower quality litters, which altered the species' decomposability trajectory on the LES, consistent with the hypothesized hump-back relationship between leaf litter mass loss and LES. This phenomenon resulted in a strongly reduced slope of cumulative mass loss on initial LES score across species.</li> <li>Our finding highlights the importance of considering interactions between the timing of detritivore activities and the timing of litter quality for better understanding the relationships between soil animals and ecosystem carbon and nutrient cycling.</li> </ol>
Estimating leaf nitrogen concentration based on the combination with fluorescence spectrum and first-derivative
Leaf nitrogen concentration (LNC) is a major indicator in the estimation of the crop growth status which has been diffusely applied in remote sensing. Thus, it is important to accurately obtain LNC by using passive or active technology. Laser-induced fluorescence (LIF) can be applied to monitor LNC in crops through analyzing the changing of fluorescence spectral information. Thus, the performance of fluorescence spectrum (FS) and first-derivative fluorescence spectrum (FDFS) for paddy rice (Yangliangyou 6 and Manly Indica) LNC estimation was discussed, and then the proposed FS+FDFS was used to monitor LNC by multivariate analysis. The results showed that the difference between FS (R2=0.781, SD=0.078) and FDFS R2=0.779, SD=0.097) for LNC estimation by using the artificial neural network (ANN) is not obvious. The proposed FS+FDFS can improved the accuracy of LNC estimation to some extent (R2=0.813, SD=0.051). Then, principal component analysis was used in FS and FDFS, and extracted the main fluorescence characteristics. The results indicated that the proposed FS+FDFS exhibited higher robustness and stability for LNC estimation (R2=0.851, SD=0.032) than that only using FS (R2=0.815, SD=0.059) or FDFS (R2=0.801, SD=0.065).
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OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.