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2,586 results for “Gradients”
Canopy gradient frass from the Coweeta Hydrologic Laboratory from 1996 to 1998
Insect frass was collected for more than two years along an elevation gradient at Coweeta Hydrologic Laboratory.
Soil chemistry along the canopy gradient from 1997 to 1999
Resin bags were buried at 10 plots on three canopy gradient sites at Coweeta Hydrologic Laboratory and the resin bag extracts were analyzed for nitrate (NO3), ammonium (NH4) and phosphate (PO4). Values will be compared with throughfall chemistry and frass weights to determine if there are any correlations due to canopy herbivory. For more information see Reynolds and Hunter, 2001 in Publications section below. We tested whether inputs from canopy herbivores would affect soil processes such as respiration, nutrient cycling, and decomposition along an elevation gradient. The five treatments we used were frass additions, throughfall additions, removal of all litter that fell during the study, removal of greenfall that fell during the study, and controls.
Soil respiration in treatment boxes on canopy gradient sites at the Coweeta Hydrologic Laboratory from 1997 to 1998
We tested whether inputs from canopy herbivores would affect soil processes such as respiration, nutrient cycling, and decomposition along an elevation gradient. The five treatments we used were frass additions, throughfall additions, removal of all litter that fell during the study, removal of greenfall that fell during the study, and controls. Soil respiration was significantly reduced on low and mid elevation sites in litter exclusion, greenfall exclusion and throughfall addition treatments (from 0.846 g CO2/m2/h for controls to 0.618, 0.667, and 0.708 g CO2/m2/h, respectively, for the three treatments).
Soil respiration at resin bag sites at canopy gradient sites
We tested whether inputs from canopy herbivores would affect soil processes such as respiration, nutrient cycling, and decomposition along an elevation gradient. The five treatments we used were frass additions, throughfall additions, removal of all litter that fell during the study, removal of greenfall that fell during the study, and controls. Soil respiration was significantly reduced on low and mid elevation sites in litter exclusion, greenfall exclusion and throughfall addition treatments (from 0.846 g CO2/m2/h for controls to 0.618, 0.667, and 0.708 g CO2/m2/h, respectively, for the three treatments).
Soil respiration and precipitation data at resin bag sites on canopy gradient sites at the Coweeta Hydrologic Laboratory in 1998 (dataset 1056)
We tested whether inputs from canopy herbivores would affect soil processes such as respiration, nutrient cycling, and decomposition along an elevation gradient. The five treatments we used were frass additions, throughfall additions, removal of all litter that fell during the study, removal of greenfall that fell during the study, and controls. Soil respiration was significantly reduced on low and mid elevation sites in litter exclusion, greenfall exclusion and throughfall addition treatments (from 0.846 g CO2/m2/h for controls to 0.618, 0.667, and 0.708 g CO2/m2/h, respectively, for the three treatments).
Nematodes in canopy gradient sites at the Coweeta Hydrologic Laboratory from 1997 to 1998
Soil nematodes were extracted from litter bags collected from canopy gradient sites as part of: Reynolds, Barbara F.. 2000. Effects of canopy herbivores on soil systems along an elevational gradient. Ph.D. Dissertation. Athens, GA: University of Georgia. These data represent total numbers of nematodes. Different trophic groups are not distinguished. Litter was a combination of red oak and red maple. Nematode counts are based on calculated dry weight of litter.
Nematode functional groups in quadrat treatments on canopy gradient plots
Previous studies have suggested that herbivory in forest canopies can influence forest floor processes such as nutrient cycling and decomposition. We studied the response of litter decomposition to a moisture/productivity gradient with manipulations of the effects of canopy herbivory at the Coweeta Hydrologic Laboratory, North Carolina. Litterbags containing Quercus rubra L. and Acerrubrum L. litter were placed at three elevations along the gradient and sampled monthly for two years. Microarthropods, nematodes, and litter mass loss responses to the productivity gradient were measured. The relative abundance of Collembola and three suborders of mites (Oribatida, Mesostigmata and Prostigmata) was compared across the gradient. Numbers of nematodes per gram dry weight of litter are reported from litterbags placed in quadrat treatment boxes on canopy gradient sites. Treatments used on quadrat boxes include frass additions (boxes 3,8,13,18,23), thrufall additions (boxes 4,9,14,19,24), controls (boxes 5,10,15,20,25), greenfall exclusion (boxes 2,7,12,17,22) and litterfall exclusion (boxes 1,6,11,16,21). Frass and throughfall treatments were initiated in spring of 1998. See Reynolds 2000.
Litter decomposition in canopy gradient plots at the Coweeta Hydrologic Laboratory in 1998
Decomposition is frequently measured using litter bags containing known amounts of litter. A set of litter bags can be sampled over time and the weight loss which is measured serves as an index of decomposition. By measuring litter breakdown rate (decomposition) of the same species of litter along the elevation gradient, we could measure variation among the different elevations due to our treatments and elevation effects. Treatments used on quadrat boxes include frass additions (boxes 3,8,13,18,23), thrufall additions (boxes 4,9,14,19,24), controls (boxes 5,10,15,20,25), greenfall exclusion (boxes 2,7,12,17,22) and litterfall exclusion (boxes 1,6,11,16,21).
Litter decomposition in quadrat treatments along elevation gradient for canopy herbivore input study at the Coweeta Hydrologic Laboratory from 1997 to 1999
Decomposition is frequently measured using litter bags containing known amounts of litter. A set of litter bags can be sampled over time and the weight loss which is measured serves as an index of decomposition. By measuring litter breakdown rate (decomposition) of the same species of litter along the elevation gradient, we could measure variation among the different elevations due to our treatments and elevation effects. Treatments included frass additions, thrufall additions, greenfall exclusion, all litter excluded, and controls.
Measurements of coarse woody debris at the Coweeta LTER Terrestrial Gradient Sites, Coweeta Hydrological Laboratory, Otto, NC from 2003 to 2014
The five Terrestrial Gradient sites were established in the early 1990s as part of the 1990 Coweeta LTER Renewal. The original terrestrial gradient sites were 20 x 40-m. In the late 1990s the plots were expanded to 80 x 80-m and later (around 1998) they were slope-corrected by Clark's lab using survey equipment. In this study, coarse woody debris (CWD) was measured in each of the five terrestrial gradient plots at the Coweeta Hydrologic Lab from 2003 through 2014. The length, diameters, and decay class of coarse wood were measured within each of the plots.
Terrestrial Gradient Litterfall Dry Mass, Coweeta LTER, 1994-2017
This project was started by Haines and Crossley in 1992 to compare leaf litter weights among the five gradient plots (though data from the first collections were not included in this dataset because the original dataset did not represent a complete quarter of collection). Litter is collected from ten 0.92x0.92 m leaf collectors within each of the gradient plots. Litter is collected on a quarterly basis (monthly in the autumn). The litter is then separated by category, dried, weighed, and processed in a Wiley mill for later nutrient analyses. Since the project first started, the collection process has expanded to include non-leaf litter (e.g., lichens, bark, and seeds), fine twigs (0-2.5 cm diameter), and medium twigs (2.5-10 cm diameter).
Measurements of Soil Bulk Density at the Coweeta Terrestrial Gradient Sites
This project is part of a larger examination of site productivity along an elevational gradient. Forest floor weights, %C, and %N were measured at each of the five terrestrial gradient plots located along an elevational gradient at Coweeta Hydrologic Lab, Otto, NC.
Measurements of Soil %C and %N at the Coweeta LTER Terrestrial Gradient Sites, Coweeta Hydrological Laboratory, Otto, NC.
This project is part of a larger examination of site productivity along an elevational gradient. Soil %C and %N were measured at each of the five terrestrial gradient plots located along an elevational gradient at Coweeta Hydrologic Lab, Otto, NC.
Measurements of Soil Water Chemistry at the Coweeta Terrestrial Gradient Sites
This project is part of a larger examination of site productivity along an elevational gradient. Five tension lysimeters were placed at each of two depths, 15 cm and bottom of Bt soil horizon, along two transects running parallel to the contour of each 40 × 20 m terrestrial gradient plot. Soil water was collected weekly and composited at the end of each month. Values are the mean value for each site/month.
Measurements of leaf litter Carbon and Nitrogen from the Coweeta LTER Terrestrial Gradient sites, Coweeta Hydrological Laboratory, Otto, NC
This project was started by Haines and Crossley in 1992 to compare leaf litter weights among the five gradient plots (though data from the first collections were not included in this dataset because the original dataset did not represent a complete quarter of collection). Litter is collected from ten 91.4 x 91.4 cm leaf collectors within each of the gradient plots. Litter is collected on a quarterly basis (monthly in the autumn). The litter is then separated by category, dried, weighed, and processed in a Wiley mill for later carbon and nitrogen analyses. Since the project first started, the collection process has expanded to include non-leaf litter (e.g., lichens, bark, and seeds), fine twigs (0-2.5 cm diameter), and medium twigs (2.5-10 cm diameter).
Leaf decomposition along the Ball Creek / Coweeta Creek elevational gradient at the Coweeta Hydrologic Laboratory from 1991 to 1992
This work was conducted in the southern Appalachian Mountains at Coweeta Hydrologic Laboratory, North Carolina, USA from 1991 to 1992. We investigated in-stream leaf decomposition in different habitat patches using leaf species that varied in their speed of processing along a first fourth-order stream gradient. Most studies of stream disturbance have been from the perspective of point or non-point discharges that impinge directly on stream communities. Streams may also receive indirect impacts when the catchments they drain are disturbed by such activities as logging. Logging has been extensive in areas drained by small to intermediate streams throughout the United States, and few streams in the Eastern United States drain forests that have escaped logging. The present study was undertaken to investigate the impact of clear-cutting on the rates at which riparian tree leaves are comminuted by first-order stream communities in the southern Appalachian Mountains.
Stem temperature at watershed 18, cove 218 gradient plot at the Coweeta Hydrologic Laboratory from 1996 to 1999
Tree stem temperature is currently being collected to determine both diurnal and seasonal variation in tree stem temperatures for all species and sizes present at the Coweeta Watershed 18 Cove 218 Gradient Plot. The purpose of the data is to characterize the tree stem temperature regimes as they relate to tree stem respiration. Data will continue to be collected until approximately December 1997. Data will then be subsequently summarized and published.
Patch occupancy of stream fauna across a land cover gradient in the southern Appalachians, USA
Field sampling of four functionally important focal stream consumers within the Little Tennessee River Basin took place in thirty-seven stream reaches between May - July 2009. Sampled reaches all drained an area less than 17 km2, and land cover varied among these reaches. This data was used to model patch occupancy to examine factors that best predicted the prevalence of the four groups.
Decomposition rates of four litter types along coastal gradients in Everglades National Park (FCE LTER), Florida, USA: 2020-2021
Leaf litter, of variable quality, was deployed along freshwater-to-marine gradients to investigate the drivers of litter breakdown in the Florida Coastal Everglades. Sea-level rise provides both stressors and subsidies to microbial communities that break down litter, and is also causing shifts in the vegetation producing litter, changing the initial quality of litter being deposited in coastal wetlands. The goal of this project was to understand the complex relationship between marine stressors and subsidies, by performing a reciprocal transplant of litter. Litter from each major vegetation species along the freshwater to marine gradient were deployed at sites in freshwater, the ecotone, mangrove forest, and in Florida Bay. This reciprocal transplant of different qualities of leaf litter into novel environments across a gradient of salinity and phosphorus will give insights into the effects of litter carbon quality, littery chemistry, microbial productivity of decomposers, and environmental chemistry as drivers of the breakdown of leaf litter.
Leaf litter, soil, and periphyton gene expression along freshwater to marine gradients in Everglades National Park (FCE LTER), Florida, USA, January 2021 and April 2021
We collected leaf litter, periphyton, and soil along freshwater to marine gradients at SRS-2, SRS-4, SRS-6, TS/PH-2, TS/Ph-3, TS/Ph-7a, and TS/Ph-10. Samples were collected in January and April of 2021 to understand how microbial communities respond to and influence the breakdown of organic matter along freshwater to marine transects. Data collection for this project is complete. For each site and litter pair we collected a subset of 2-3 g wet mass of litter, a grab sample of soil, and a grab sample of periphyton for each site. All subsamples were preserved at -20°C until extraction, which took place up to a year after initial collection. Samples were sent to Novogene (Novogene Co. Ltd., Beijing, China) for the total RNA extraction followed by metatranscriptome sequencing. We selected n = 12 genes/gene families encoding for focal enzymes to investigate which are important to the breakdown of organic matter: Dioxygenases (associated with aerobic respiration), Sulfatases (associated with the release of sulfates from complex molecules), sulfite reductases (associated with sulfite reduction), methyl coenzyme M reductase and formylmethanofuran (associated with methanogenesis), nitrite reductases (associated with nitrite reduction), cellobiosidase, glucosidase, and xylosidase (associated with cellulose breakdown), phenol oxidase (associated with lignin breakdown), acid phosphatase (associated with phosphate acquisition in acidic environments), and alkaline phosphatase (associated with phosphate acquisition in basic environments). For each gene/family of interest, we searched all annotated transcripts for all entries corresponding to that gene/family and combined all values for a total expression. We selected n = 6 monophyletic microbial functional groups, representing sulfate reducers, sulfate oxidizers, methane oxidizers, methanogens, nitrite oxidizers, and ammonia oxidizers associated with sulfate and methane cycling. We filtered all annotated transcripts for all specie
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