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openOpenDec 2015View details →

Percent carbon and nitrogen of leaves from shoots harvested at three levels in the canopy from 19 plots dominated by S. pulchra and B. nana shrubs near LTER Shrub plots at Toolik Field Station, AK the summer of 2012.

The percent carbon and nitrogen from leaves of shoots harvested from 1m x 1m point frame plots the summer of 2012 at Toolik Lake, Alaska. were measured on a ThermoScientific 2000. For each point frame plot, six shoots were harvested from upper, middle, and low sections of the canopy. The photosynthetic capacity of each shoot was analyzed with a LiCor 6400 infra-red gas analyzer by being run through a light response and A/Ci curve. The area of the shoot as viewed from the stop of the LiCor opaque, confer chamber ("silhouette area") as well as the area of each shoot organ type was measured. These data are published separately, though methods are described below.

openOpenMar 2009View details →

Nitrogen cycling at treeline. II. Percent Soil Carbon and Nitrogen

We studied spatial and temporal patterns of nitrogen pools and fluxes in soils at treeline and forested sites within three mountain ranges across a 785 km transect in Alaska during 2001- 2002. We measured pools of soil mineral (ammonium and nitrate) and organic (amino acid and microbial biomass) nitrogen, in situ rates of net mineralization, net nitrification, net amino acid production, and decomposition, as well as soil carbon turnover in a laboratory incubation experiment. A complete characterization of the study can be found in Loomis et al. (2006).

openOpenOct 2015View details →

Effects of permafrost thaw on nitrogen availability and plant-soil interactions in a boreal Alaskan lowland: I - Percent Cover Data 2013

This dataset examines shifts in plant community structure along a lowland boreal permafrost thaw chronosequence. Data was collected in 2013 at the APEX Beta and forested study plots, located adjacent to the BNZ experimental forest. Percent cover data was collected for subcanopy vascular and nonvascualr vegetation in July 2013.

openCustomJan 2020View details →

Soil percent carbon and nitrogen from 9 hillslopes sites in Macon County, North Carolina, within the Upper Little Tennessee River Basin

Percent carbon and percent nitrogen of soil were analyzed as part of the hillslope plots in Macon County, North Carolina. There were 9 hillslope sites representing a gradient of development, including forested, valley agriculture, and mountain housing developments. There were 12 10 x 10-m plots at each site. A soil probe was used to collect soils from 3 depths at each plot: 0-10 cm, 10-30 cm, and 30 + cm. Soil was then dried, processed, and analyzed for percent C & N at the Coweeta Analytical Laboratory.

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Percent carbon, percent nitrogen, del13C and del15N of above ground plant and belowground stem biomass samples from experimental plots in moist acidic and moist non-acidic tundra, 2000, Arctic LTER, Toolik Lake, Alaska.

Percent carbon, percent nitrogen, del13C and del15N were measured from above ground plant and belowground stem biomass samples from experimental plots in moist acidic and moist non-acidic tundra. Biomass data are in 2000lgshttbm.dat.

openOpenDec 2015View details →

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Percent carbon and percent nitrogen of above ground plant and belowground stem biomass samples from experimental plots in moist acidic and moist non-acidic tundra, 2001, Arctic LTER, Toolik Lake, Alaska.

Percent carbon and percent nitrogen were measured from above ground plant and belowground stem biomass samples from experimental plots in moist acidic and moist non-acidic tundra. Biomass data are in 2001lgshttbm.dat.

openOpenDec 2015View details →

Percent light penetration: Long-Term Nitrogen Deposition: Population, Community, and Ecosystem Consequences

The purpose of this experiment is to measure how adding nitrogen over a long time will affect the number of species, the type of species present, the amount of annual growth, and the change from year to year in the growth of each species in a plant community which is also relieved of grazing by large and small mammals. The experiment is being conducted within fields (A, B, C, and D) which were initially low in soil nutrients. There are 8 different levels of nitrogen addition with other nutrients added to ensure that nitrogen remains the limiting nutrient, and a control which receives no nutrients. There are 6 replicates of the 9 treatments in fields A, B, and C and 5 replicates in field D. The treatments were randomly assigned to the plots. In fields A, B, and C the plots are in 6 by 9 grids and are 4 by 4 meters in size with 1 meter aisles between plots. In field D the plots are 1.5 by 4 meters and are placed in a 3 by 17 grid. The plots are enclosed by a fence to keep out mammalian herbivores. Gophers are trapped and removed as they appear. Nitrogenfertilizer (NH4NO3) is applied twice per year, once in early May and once in late June. This experiment was begun in 1982 by David Tilman.

Percent light penetration: The Effect of Nitrogen Addition and Different pH Levels on Microorganism Populations

The purpose of this experiment was to measure the effect of NH4NO3 addition and different levels of pH on microorganism populations. The experiment was located in field B. This experiment was laid out as a full factorial design with 3 nitrogen levels and 4 pH levels. The pH levels strived for are 4.0, 5.5, 6.5, and controls. The nitrogen levels are E, G, and I are defined in fertilization details. The experiment had 4 replicates. The treatments were randomly assigned to the 48 plots. The plots were 4 by 4 meters and were laid out in a 6 by 8 grid. On May 5, 1995, a wildfire burned all of the plots in experiment 24 in field B.

Plant species percent cover data: Traits: Competition and Resource Reduction for Five Grass Species Grown in Monoculture and Competition in Soils with Different Nitrogen Availabilities

This experiment was designed to determine the relationships between plant traits, successional status, and resource reduction for five grass species that were grown for three years in monoculture in replicated field plots on soils prepared to have different availabilities of nitrogen. It also determines the results of competition experiments among various combinations of these species as well as the differing feedback effects of each species on soil nitrogen mineralization rates. All of this work has motivated the desire to more fully understand the mechanisms of interactions among plants and their resources, in the belief that this might eventually allow predictions of the dynamics, diversity, and composition of plant communities.

Percent light penetration and maximum plant height: Traits: Competition and Resource Reduction for Five Grass Species Grown in Monoculture and Competition in Soils with Different Nitrogen Availabilities

Percent light penetration: Components of Plant Competition Along an Experimental Gradient of Nitrogen Availability

This experiment was set up in Field C, on top of the already existing experiment C011. For a description of the plot layout, see E011. For a list of fertilizer treatments for each plot, see file trmte11 and fertilization details. The object of this research was to measure the intensity of above and below-ground competition along a gradient of soil resource availability. Neighbor effects were quantified by measuring the biomass, growth, morphology and survivorship of three species transplanted into vegetation along a gradient of soil nitrogen availability. Transplants were used to test for an inverse relationship between above and below-ground competition, variation in the intensity of competition at different levels of nutrient availability, and reversal of competitive hierarchies. Eight plots of each nitrogen treatment were randomly selected and used for competition experiments. Three competition treatments were used to measure the above and below-ground effects of neighbors on transplanted seedlings at each rate of nitrogen supply. Transplants were grown in subplots with no neighbors, or in subplots with the roots but not shoots of neighbors, or in subplots with all above- and below-ground parts of neighbors present. No neighbor treatments were imposed by driving a ring of galvanized sheet steel (50cm in diameter, 15cm tall) into the ground until the top of it was at the soil surface and then killing all the plants in the enclosed circle with a systemic, rapidly decomposing herbicide (Roundup). Transplants were grown with only the roots of neighbors using white plastic garden net (50x50cm; mesh:1x2cm) to tie back the shoots and leaves of neighbors so that a transplant in the center of the net was not shaded by neighbors but was surrounded by neighbor roots. The all neighbors treatment consisted of a transplant grown in the center of a 50cm x 50cm subplot of undisturbed vegetation. Treatments were replicated five times for each of three transplanted species in each

Percent light penetration: Plant Competition Under Different Nitrogen Levels:A Garden Experiment

This garden plot experiment is located next to the E026 gardens in Field E (Old Field 44). This garden contained monocultures of major grass species from across the grassland biome of North America, and also 3 legume species (E070). The design and purpose were similar to E026, except the plots were larger. The basic experimental design consisted of growing plants in monoculture and in various competitive combinations on each of 14 different soil mixtures. In 1988 a bulldozer was used to remove 30 inches of top soil at the site. To each plot a certain amount of black dirt, ranging from 0.3 inches to 10 inches, was added. Total carbon ranged from 0.1928% to 5.63134% and total nitrogen ranged from 0.0158% to 0.4591%. The exact amounts of black soil added to each plot are described in the field operations. Equal amounts of MgSO4, CaCO3, P2O5 \

Plant species percent cover data: Plant Competition Under Different Nitrogen Levels:A Garden Experiment

Percent light penetration: Long-Term Nitrogen Deposition During Grassland Succession

The purpose of this experiment is to measure how initially disturbing an area and adding nitrogen over a long time will affect the number of species, the type of species present, the amount of annual growth, and the change from year to year in the growth of each species in a plant community which is also relieved of grazing by large and small mammals. This experiment is conducted within fields (A, B, and C) which were initially low in soil nutrients. The ground was disturbed by thoroughly disking the area prior to establishment of the experiment. There are 8 different levels of nitrogen addition with other nutrients added to ensure that nitrogen remains the limiting nutrient, and a control which receives no nutrients. Nitrogen fertilizer (NH4NO3) is applied twice per year, once in early May and once in late June. There are six replicates of each treatment per field. The treatments were randomly assigned to plots of size 4 by 4 meters. The plots are in 6 plot by 9 plot grids with 1 meter aisles between plots. The plot grids are enclosed by a fence to keep out mammalian herbivores. Gophers are trapped and removed as they appear. In the spring of 1992, subexperiments E097 and E098 were established. E097 is in fields A and C where randomly selected plots within each treatment no longer receive fertilizer. E098 is in field B where randomly selected plots within each treatment are burned. Note that the design of E002 is similar to E001 except E002 was thoroughly disked prior to establishment.

Plant species percent cover data: Interactive Effects of Deer, Fire and Nitrogen

In 2000 we began to examine impacts of three anthropogenic effects on successional grasslands in an area with rapid woody encroachment toward white pine forest. We established a factorial experiment that manipulates N (0 or 3 g m-2 yr-1), fire (none or every 2nd year), and deer (fenced or open to deer), with a total of 32 plots, each 20 x 20 m. We hypothesized that the response of this ecosystem to the combined effects of fire, N, and herbivory would depend on the ability of pine and other species to invade and the magnitude of their response to the different disturbance factors: warm-season grasses increase with and encourage fire, resist herbivores, and inhibit woody plant invasion (Davis et al. 1998, Inouye et al. 1994); cool-season plants are favored by N deposition (Tilman 1987) but are fire-intolerant and palatable to herbivores; legumes tolerate fire but decrease with herbivory and N deposition; and finally, woody plants are fire-intolerant and may be more susceptible to herbivory. We are measuring treatment effects on composition and diversity of plants and consumers (insects, small mammals, lizards) as well as plant and soil C and N.

Percent light penetration: Nitrogen Addition and Dynamics of Recovery from Cessation of N Addition

This experiment was established on top of E002 in fields A and C. In the spring of 1992, 3 randomly chosen replicates of each nutrient treatment of experiment E002 were chosen to receive no more fertilizer. For a description of these plots, see E002. For a description of fertilizer added to E097, see file fertilization details. For a list of treatments, see the treatment layouts in file trmte97.

Percent light penetration: Fire X Nitrogen: Interactive Effects in a Prairie-Like Grassland

This experiment was established on top of E002 in field B. In the spring of 1992, 3 randomly chosen replicates of each nutrient treatment of experiment E002 were chosen to be burned each spring. For a description of these plots, see E002. For a list of treatments, see the treatment layouts in file trmte98.

Percent light penetration: Herbivory by Nitrogen Interactive Effects on Community and Ecosystem Processes and Dynamics

E172 is an herbivory experiment established by Dave Tilman in fall 2004 by enclosing in deer fences three randomly selected plots from the six replicates of each control and each treatment in the N addition E001 experiment in field C. These plots still receive the nutrient treatments prescribed in the Experiment 001 protocols. From 1982-2004 a fence containing all of e001 plots in Field C was designed to exclude deer and all small mammals, including mice, voles and pocket gophers. This fence was removed in Fall of 2004 and individual plots designated for e172 were enclosed in deer fences. The purpose of E001 was to measure how adding nitrogen over a long time would affect the number of species, the type of species present, the amount of annual growth, and the change from year to year in the growth of each species in a plant community which is also relieved of grazing by large and small mammals. There are 8 different levels of nitrogen addition with other nutrients added to ensure that nitrogen remains the limiting nutrient, and a control which receives no nutrients. The plots are in a 6 by 9 grid and are 4 by 4 meters in size with 1 meter aisles between plots. Nitrogen fertilizer (NH4NO3) is applied twice per year, once in early May and once in late June.