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Methods for Experiment 015 -

Burning Methods

The burn compartments were first set-up in 1964 with the first burning of burn compartment number 1. The burn compartments are separated from each other by firebreaks which are maintained by discing with a tractor prior to burning. This creates a 6 foot wide firebreak that is free of vegetation and debris, surrounding each burn compartment. A backfire is started, using drip torches, to widen the firebreak. Drip torches are then used to start the burn compartment on fire. The firebreaks are continuously patrolled to check for escaped fires. These are put out immediately with help from the high pressure water hose. Some burn compartments are not burned and are used as control compartments. The other burn compartments are burned according to various schedules which are maintained on a yearly basis.

Field Operations: Burning

The burn compartments were set up in 1964 with the first burn in compartment number 1. Burn compartments 3, 4 and 5 were first burned in 1965. Burn compartment 7 was first burned in 1966 and compartment 8 in 1967. Burn compartment 13 was first burned in 1968 and compartment 11 in 1969. The compartments are usually burned in April or May. The burns of these compartments are maintained on a yearly basis according to the following schedule:

Treatment layout : trmte15

Burn Compartment Treatments: A=control (not burned) B=burned 2/15 years C=burned 3/16 years D=burned 4/9 years E=burned 8/17 years F=burned 9/17 years G=burned 11/19 years H=burned 3/5 years I=burned 17/19 years J=burned every year

In February 1992, the Cedar Creek burn compartments were reassigned numbers to avoid future confusion. The following is a conversion table:

pce015 - Plant species percent cover data

Sampling

In 1984, percent cover estimates of vegetation, litter and bare soil were done on all plots in each of the burn compartments. Soil samples and light meter readings were also taken at each plot in all of the compartments. At the center of each quadrat (plot), a soil core was taken to a depth of 10 cm. Plots were 0.5m x 1m. Three types of vegetation were sampled: forbs, shrubs and trees. Forbs are any vegetation that is non-woody when the plant is in its reproductive stage of life. Shrubs are any species that tends to have multiple stems arising from the base and that has, at most, a maximum height of 5m. Trees were separated into three categories: seedlings, saplings and trees. A seedling is a species designated as a "tree", where the individual observed is less than 30 cm high. A sapling is a species designated as a "tree", where the individual is taller than 30cm but has a diameter at breast height (dbh) of less than 4 inches. A tree is a species designated as a "tree", where the individual has a dbh greater than 4 inches. Along each transect, in each burn compartment, six points were marked. One each at the 0, 10, 20, 30, 40 and 50 meter spot along the transect. At each of these points, a 1 x .5m quadrat was outlined. In each of the quadrats, percent cover of the area for each species was recorded. Percent cover of bare ground was also recorded. If a tree was in the quadrat, the quadrat was shifted along the transect towards the zero meter point. Using the same six points along the transects, the point-quarter method was used for observing shrubs. The point on the transect was divided into four sections. The dividing lines were along the transect line and a line perpendicular to the transect. In each section of the quadrat, the distance to the nearest shrub from the center of the quadrat was measured. The species name of the shrub and this distance were recorded. The entire experimental area is 50m x 75m. In this area, all trees were recorded. The species name and dbh for each tree was recorded. In 1989, eleven of the 12 plots set up by Tester et al. in 1984 were resampled in September and October of 1989 for woody vegetation only. The purpose of the study was to assess the rate of mortality caused by the 1987-1989 drought. Trees were defined as mature (>= 10cm dbh) (Tester defined mature as >5 cm dbh), sapling (1-9.9cm dbh), and seedling (<10 cm height-150 cm height, which is approximately = 0.9cm dbh). Shrubs were measured by height of stems (cm). Mature stems were recorded as alive (0), dead standing (1) or dead snapped (2). Note: as part of experiment E094, the herbaceous layer for six of the twelve plots was resampled (plots 1, 3, 4, 5, 7 and 17=compartment 9S and plot 15 in E094). Tester's numbers for the plots in experiment E015 differed from both the compartment number and numbers used by D. Faber-Langendoen in study E094. A chart is shown below indicating the correspondence between the numbers. Plots for the tree mortality study use the DF-L numbers. Compartment Number* Tester(1989)** DF-L 1989*** 1 1 1 3 3 3 4 4 4 5 5 5 7 7 7 8 8 8 9N 16 9 10 10 10 11 11 11 13 13 13 9S 17 15 1A 15 16 *Data sheets for 1984 have these numbers. ** J. Tester. 1989. Effects of fire frequency on oak savanna in east-central Minnesota. Bull. Torrey Bot. Club 116:134-144. [1154] *** D. Faber-Langendoen and J.R. Tester. 1993. Oak mortality in sand savannas following drought at Cedar Creek, Minnesota. Bull. Torrey Bot. Club: 120:248-256. [1043] Overall plot design: A 75m x 50m plot was established. Along the baseline, a permanent stake was placed at the 0, 25, 50 and 75m mark. A similar set of stakes were placed 50m away. Using these stakes, 4 transects can be established, each 50m in length. Six sections (25 x 25m) can also be created by drawing a line across the 25m mark (these are numbered 1-6). At the corner of each section by the stakes, two nested plots are located, first a 10 x 10m (for saplings A-F) then a 3.2 x 3.2m (for shrubs and seedlings a-f). Shrubs were not sampled by point-quarter, as was done in 1984. Rather, a 3.2 x 3.2m (=10 m2) quadrat was established in each of the six corners of the six sections. Shrub and tree seedling density and stem height were recorded. Sapling trees were measured in 10 x 10m plots enlarged over the shrub and seedling plots. Where saplings are very sparse, they are counted in the entire 25 x 25m section. Mature trees were measured in the 25 x 25m section. Tree diameter at breast height (dbh) was measured and canopy height and vigor were estimated. Vigor was measured on a five point scale, from 0=0% live (i.e. dead), 1=1-20%, 2=21-40%, 3=41-60%, 4=61-80%, 5=81=100% live canopy. If dead, the tree was recorded as either dead standing, dead snapped or dead fallen. Stems were subjectively assessed as to whether they were parts of one individual or not. Multiple stems were grouped in the data. A trunk that forked at a height of less than 1.37m was considered a multiple stemmed individual (e.g. even bur oaks that had two large branches diverging at 0.8m above the ground were recorded as two stemmed individuals). All mature stems in a series of plots were also tagged at breast height. If the individual tree had multiple stems only one stem was tagged. This measurement was always recorded first in the data.

Vegetation Sampling

This experiment is sampled approximately every 5 years, starting in 1984. The set up of the transects and plots in the burn compartments is the same as for those in E014. Sampling (percent cover estimates) in E015 is also the same as in E014. However, in addition to E014 sampling, E015 considers there to be a second (shrub) layer. Similar estimations of percent cover by species for the shrub layer are also done. The shrub layer does not always sum to 100%. Tree seedlings or shrubs that are the same height as plants in the herbaceous layer are counted as part of the herbaceous layer, and not as part of the shrub layer. E015 was sampled differently in 1989.

she015 - Shrub data

Sampling

In 1984, percent cover estimates of vegetation, litter and bare soil were done on all plots in each of the burn compartments. Soil samples and light meter readings were also taken at each plot in all of the compartments. At the center of each quadrat (plot), a soil core was taken to a depth of 10 cm. Plots were 0.5m x 1m. Three types of vegetation were sampled: forbs, shrubs and trees. Forbs are any vegetation that is non-woody when the plant is in its reproductive stage of life. Shrubs are any species that tends to have multiple stems arising from the base and that has, at most, a maximum height of 5m. Trees were separated into three categories: seedlings, saplings and trees. A seedling is a species designated as a "tree", where the individual observed is less than 30 cm high. A sapling is a species designated as a "tree", where the individual is taller than 30cm but has a diameter at breast height (dbh) of less than 4 inches. A tree is a species designated as a "tree", where the individual has a dbh greater than 4 inches. Along each transect, in each burn compartment, six points were marked. One each at the 0, 10, 20, 30, 40 and 50 meter spot along the transect. At each of these points, a 1 x .5m quadrat was outlined. In each of the quadrats, percent cover of the area for each species was recorded. Percent cover of bare ground was also recorded. If a tree was in the quadrat, the quadrat was shifted along the transect towards the zero meter point. Using the same six points along the transects, the point-quarter method was used for observing shrubs. The point on the transect was divided into four sections. The dividing lines were along the transect line and a line perpendicular to the transect. In each section of the quadrat, the distance to the nearest shrub from the center of the quadrat was measured. The species name of the shrub and this distance were recorded. The entire experimental area is 50m x 75m. In this area, all trees were recorded. The species name and dbh for each tree was recorded. In 1989, eleven of the 12 plots set up by Tester et al. in 1984 were resampled in September and October of 1989 for woody vegetation only. The purpose of the study was to assess the rate of mortality caused by the 1987-1989 drought. Trees were defined as mature (>= 10cm dbh) (Tester defined mature as >5 cm dbh), sapling (1-9.9cm dbh), and seedling (<10 cm height-150 cm height, which is approximately = 0.9cm dbh). Shrubs were measured by height of stems (cm). Mature stems were recorded as alive (0), dead standing (1) or dead snapped (2). Note: as part of experiment E094, the herbaceous layer for six of the twelve plots was resampled (plots 1, 3, 4, 5, 7 and 17=compartment 9S and plot 15 in E094). Tester's numbers for the plots in experiment E015 differed from both the compartment number and numbers used by D. Faber-Langendoen in study E094. A chart is shown below indicating the correspondence between the numbers. Plots for the tree mortality study use the DF-L numbers. Compartment Number* Tester(1989)** DF-L 1989*** 1 1 1 3 3 3 4 4 4 5 5 5 7 7 7 8 8 8 9N 16 9 10 10 10 11 11 11 13 13 13 9S 17 15 1A 15 16 *Data sheets for 1984 have these numbers. ** J. Tester. 1989. Effects of fire frequency on oak savanna in east-central Minnesota. Bull. Torrey Bot. Club 116:134-144. [1154] *** D. Faber-Langendoen and J.R. Tester. 1993. Oak mortality in sand savannas following drought at Cedar Creek, Minnesota. Bull. Torrey Bot. Club: 120:248-256. [1043] Overall plot design: A 75m x 50m plot was established. Along the baseline, a permanent stake was placed at the 0, 25, 50 and 75m mark. A similar set of stakes were placed 50m away. Using these stakes, 4 transects can be established, each 50m in length. Six sections (25 x 25m) can also be created by drawing a line across the 25m mark (these are numbered 1-6). At the corner of each section by the stakes, two nested plots are located, first a 10 x 10m (for saplings A-F) then a 3.2 x 3.2m (for shrubs and seedlings a-f). Shrubs were not sampled by point-quarter, as was done in 1984. Rather, a 3.2 x 3.2m (=10 m2) quadrat was established in each of the six corners of the six sections. Shrub and tree seedling density and stem height were recorded. Sapling trees were measured in 10 x 10m plots enlarged over the shrub and seedling plots. Where saplings are very sparse, they are counted in the entire 25 x 25m section. Mature trees were measured in the 25 x 25m section. Tree diameter at breast height (dbh) was measured and canopy height and vigor were estimated. Vigor was measured on a five point scale, from 0=0% live (i.e. dead), 1=1-20%, 2=21-40%, 3=41-60%, 4=61-80%, 5=81=100% live canopy. If dead, the tree was recorded as either dead standing, dead snapped or dead fallen. Stems were subjectively assessed as to whether they were parts of one individual or not. Multiple stems were grouped in the data. A trunk that forked at a height of less than 1.37m was considered a multiple stemmed individual (e.g. even bur oaks that had two large branches diverging at 0.8m above the ground were recorded as two stemmed individuals). All mature stems in a series of plots were also tagged at breast height. If the individual tree had multiple stems only one stem was tagged. This measurement was always recorded first in the data.

Vegetation Sampling

This experiment is sampled approximately every 5 years, starting in 1984. The set up of the transects and plots in the burn compartments is the same as for those in E014. Sampling (percent cover estimates) in E015 is also the same as in E014. However, in addition to E014 sampling, E015 considers there to be a second (shrub) layer. Similar estimations of percent cover by species for the shrub layer are also done. The shrub layer does not always sum to 100%. Tree seedlings or shrubs that are the same height as plants in the herbaceous layer are counted as part of the herbaceous layer, and not as part of the shrub layer. E015 was sampled differently in 1989.

tre015 - Tree data

Sampling

In 1984, percent cover estimates of vegetation, litter and bare soil were done on all plots in each of the burn compartments. Soil samples and light meter readings were also taken at each plot in all of the compartments. At the center of each quadrat (plot), a soil core was taken to a depth of 10 cm. Plots were 0.5m x 1m. Three types of vegetation were sampled: forbs, shrubs and trees. Forbs are any vegetation that is non-woody when the plant is in its reproductive stage of life. Shrubs are any species that tends to have multiple stems arising from the base and that has, at most, a maximum height of 5m. Trees were separated into three categories: seedlings, saplings and trees. A seedling is a species designated as a "tree", where the individual observed is less than 30 cm high. A sapling is a species designated as a "tree", where the individual is taller than 30cm but has a diameter at breast height (dbh) of less than 4 inches. A tree is a species designated as a "tree", where the individual has a dbh greater than 4 inches. Along each transect, in each burn compartment, six points were marked. One each at the 0, 10, 20, 30, 40 and 50 meter spot along the transect. At each of these points, a 1 x .5m quadrat was outlined. In each of the quadrats, percent cover of the area for each species was recorded. Percent cover of bare ground was also recorded. If a tree was in the quadrat, the quadrat was shifted along the transect towards the zero meter point. Using the same six points along the transects, the point-quarter method was used for observing shrubs. The point on the transect was divided into four sections. The dividing lines were along the transect line and a line perpendicular to the transect. In each section of the quadrat, the distance to the nearest shrub from the center of the quadrat was measured. The species name of the shrub and this distance were recorded. The entire experimental area is 50m x 75m. In this area, all trees were recorded. The species name and dbh for each tree was recorded. In 1989, eleven of the 12 plots set up by Tester et al. in 1984 were resampled in September and October of 1989 for woody vegetation only. The purpose of the study was to assess the rate of mortality caused by the 1987-1989 drought. Trees were defined as mature (>= 10cm dbh) (Tester defined mature as >5 cm dbh), sapling (1-9.9cm dbh), and seedling (<10 cm height-150 cm height, which is approximately = 0.9cm dbh). Shrubs were measured by height of stems (cm). Mature stems were recorded as alive (0), dead standing (1) or dead snapped (2). Note: as part of experiment E094, the herbaceous layer for six of the twelve plots was resampled (plots 1, 3, 4, 5, 7 and 17=compartment 9S and plot 15 in E094). Tester's numbers for the plots in experiment E015 differed from both the compartment number and numbers used by D. Faber-Langendoen in study E094. A chart is shown below indicating the correspondence between the numbers. Plots for the tree mortality study use the DF-L numbers. Compartment Number* Tester(1989)** DF-L 1989*** 1 1 1 3 3 3 4 4 4 5 5 5 7 7 7 8 8 8 9N 16 9 10 10 10 11 11 11 13 13 13 9S 17 15 1A 15 16 *Data sheets for 1984 have these numbers. ** J. Tester. 1989. Effects of fire frequency on oak savanna in east-central Minnesota. Bull. Torrey Bot. Club 116:134-144. [1154] *** D. Faber-Langendoen and J.R. Tester. 1993. Oak mortality in sand savannas following drought at Cedar Creek, Minnesota. Bull. Torrey Bot. Club: 120:248-256. [1043] Overall plot design: A 75m x 50m plot was established. Along the baseline, a permanent stake was placed at the 0, 25, 50 and 75m mark. A similar set of stakes were placed 50m away. Using these stakes, 4 transects can be established, each 50m in length. Six sections (25 x 25m) can also be created by drawing a line across the 25m mark (these are numbered 1-6). At the corner of each section by the stakes, two nested plots are located, first a 10 x 10m (for saplings A-F) then a 3.2 x 3.2m (for shrubs and seedlings a-f). Shrubs were not sampled by point-quarter, as was done in 1984. Rather, a 3.2 x 3.2m (=10 m2) quadrat was established in each of the six corners of the six sections. Shrub and tree seedling density and stem height were recorded. Sapling trees were measured in 10 x 10m plots enlarged over the shrub and seedling plots. Where saplings are very sparse, they are counted in the entire 25 x 25m section. Mature trees were measured in the 25 x 25m section. Tree diameter at breast height (dbh) was measured and canopy height and vigor were estimated. Vigor was measured on a five point scale, from 0=0% live (i.e. dead), 1=1-20%, 2=21-40%, 3=41-60%, 4=61-80%, 5=81=100% live canopy. If dead, the tree was recorded as either dead standing, dead snapped or dead fallen. Stems were subjectively assessed as to whether they were parts of one individual or not. Multiple stems were grouped in the data. A trunk that forked at a height of less than 1.37m was considered a multiple stemmed individual (e.g. even bur oaks that had two large branches diverging at 0.8m above the ground were recorded as two stemmed individuals). All mature stems in a series of plots were also tagged at breast height. If the individual tree had multiple stems only one stem was tagged. This measurement was always recorded first in the data.