A Day in the Lab: Plant Data Collection

Jered Korfhage and Katie Sagarin

After harvesting biomass and collecting data last week, the next step was to process the samples. This was also the last step we needed to take before we could analyze our data and draw conclusions about our results. Hopefully we'll see that salt has had a significant detrimental effect on our plants.

Dr. Drenovsky struggles to open
a tin can with a hammer.

The soil collected in tins in last week’s lab had been dried completely. Some lids had even cemented closed, to the point where a hammer was required to dislodge them. After struggling to remove some of the lids, we carefully measured 40 grams of soil from each tin, and placed each sample into a labeled plastic bottle. We added 200 ml of distilled water to each bottle to create a 1:5 mixture. All of the samples were put in a shaker for fifteen minutes to mix the soil and dissolve any salts into the water. These then sat for an hour to make sure everything dissolved, and then were shaken again to make the liquid uniform in composition.

Soil in the shaker

This mixture of soil and water was then vacuum-filtered (Watch how to vacuum filter here). This involved hooking a flask up to a vacuum to separate the soil from the liquid, a small portion of which was poured into a small, labelled vial. Electrical conductivity (EC) was measured for each vial by inserting the probe of an electrical conductivity meter into the liquid (Watch how to use an EC meter here). Electrical conductivity can be used to estimate the amount of dissolved salt in the mixture (more information here).

Vacuum filtration

The EC measures we observed matched our expectations. We saw a trend of increasing EC with increasing salt treatment. In other words, the 0 mM-treated soil had a lower EC than the 50 mM which had a lower EC than the 100 mM-treated soil.

The aboveground plant material and roots collected last week had also been dried. Each sample was weighed to the nearest 0.1 gram, unless it was lighter than 0.1 gram in which case it was measured to the nearest 0.001 gram. All samples were gently brushed to remove soil and sand before weighing. The biomass observed also matched our expectations. The 100 mM-treated plants were either dead or small, whereas the 0 mM-treated plants were alive and sometimes thriving.

Measuring electrical conductivity

At the end of the lab, each group entered their EC, aboveground, and below-ground biomass data into the same Excel spreadsheet, for later analysis. Based on our observations, we feel optimistic that our data will support our hypotheses.

 Results! Effects of Salinity on Stressed Common Roadside Plants

By: Natalie Fry and Meghan Kelley

__________________________________________________

 

 

Eariler this semester of Fall 2013, in the blog entitled "Trade-off of Salting Winter Roads: Human Safety vs. Plant Survival," our Plant Ecology class at John Carroll University set up a laboratory experiment in order to test different concentrations of salt on common roadside plants to determine how tolerant certain species (Purple Coneflowers, Black-Eyed Susans, Shasta Daisies, and Mexican Asters) are to man-made stressors, such as salted winter roads. During this last week of November 4, 2013, we were able to begin assessing the results on our study plants.
 

The first step before harvesting dead and alive plants is to record the observations of how plant individuals of each species look, by examining characteristics such as leaf senescence or dropped leaves, leaf coloration abnormalities like tip yellowing, and morphological drying, wilting, or withered plant leaves and stems, as can be seen in the picture below. For more information about how plants cope with salt, visit the page for the Society of Experimental Biology.

 

Qualitatively, of the four species, it appeared that the Purple Coneflower (ECPU) did not do quite as well with the salt stress as some of the other plant species.  For example, the Shasta Daisy (CHMA) in this photo is clearly green and growing better at the highest salt concentration than the Purple Coneflower grew at the intermediate salt concentration. Observations such as these were recorded in addition to the counting of plants that lived and died for each species, for each salt concentration.  Overall, as stated in the previous blog, five experimental blocks were created with replicates of each species for the salt treatments- however, as an example, only one block will be used to indicate some preliminary observational results.  Of the twelve original plants in this block, only five survived, and three of those five were from controls that were not salt stressed.  Therefore, we can say that these four common roadside plants are not all amenable to winter salinity treatments of roads that can accumulate toxic salt levels over time. However, more tests were also performed in this lab to further strengthen this claim or to add additional information about physiological tolerance in these species.

For more definitive quantitative measurements, our class used a LICOR machine, which includes a clamp for leaves in a 2x3 centimeter frame in order to measure the amount of light captured for photosynthesis as well as other functions linked to photosynthesis. The LICOR machine used in this study is pictured below, showing its easy to read digital monitor for assessing measurements.

 

Next, a Scholander Pressure Bomb was used to measure the water potential of different leaves of the species that lived, which were only the Shasta Daisy, the Black-Eyed Susan, and the Mexican Aster for one block, not the Purple Coneflower.  The leaf is placed in the pressure bomb upside down and sealed, in order to allow the pressurized nitrogen gas to force water to the center of the leaf petiole. This water movement has to be monitored by someone to determine the correct point of pressure of the plant's water potential, as seen in lower right photo.

Finally, the aboveground (stems and leaves) and the belowground (roots) biomass were harvested along with a soil sample for the purpose of drying the organic materials to weigh for our final results.  Aboveground biomass was clipped with shears at the soil surface, and roots were collected by filtering soil through a metal sieve into a bucket. These will be weighed at a later date. Following the analysis of all data collected in this lab, statistics will be run to make conclusions about this study.  Some discussionary points to help examine the results could include the use of fluorescent lights in the greenhouse in place of sunlight, which was not available during the measurements of this study. Seen in the picture below, plants were harvested under these conditions indoors. Also, possible sources of error along with relevant plant biology could be discussed for drawing further conclusions as to which of the four plant species is the most salt tolerant and would therefore be more likely to survive along midwest and northern roads.

 

 

 

Additional Links:

 

University of California: "Salt Injury in Strawberries" (2012)

 

North Carolina State University: "Got Salt? Winter Weather May Be Toxic to Plants" (2013)

 

 

 

 

 

 

 



Physiological Ecology: An Introduction to Methods

Dr. Drenovsky explaining
components of the LICOR-6400

On the 31^st of October 2013, the BL 435/535 class became acquainted with the LICOR-6400 and the pressure bomb so that for next week’s lab we will be able to harvest and record data of our greenhouse experiment.  The purpose of the LICOR-6400 is to measure gas exchange in plants while the Scholander-type pressure bomb measures leaf water potential. 

Students taking measurements
with the LICOR-6400

In order to collect data using these two machines, learning how to set them up was important.  Our professor gave us a thorough explanation for each machine.  The class was split in two groups to use the two LICOR-6400 machines, affectionately known as LUCY and OSCAR.  We were able to gain hands-on experience as our professor explained how to connect the parts of the instrument.  Although the LICOR-6400 can be easily set up, there is a pre-checklist that must be done before using the machine.  Noting the chamber, the cables, the console, and the chemical tubes were instructions given to us so that we become more aware of the machine before beginning our measurements. We were then able to begin measurements.  Extra samples of the study species for our greenhouse experiment were used.  Due to overcast weather conditions, additional lighting was used to increase photosynthetic rates.  The leaf of a specimen was placed in the chamber, which was held there until the conditions inside the chamber equilibrated.  Upon equilibration, the data was logged in the machine.  We had to repeatedly check during measurements that the Infrared Gas Analyzers (IRGAs) were matching to ensure accuracy.  This simply means to ensure that the carbon dioxide reference and sample are read as equivalent as when a balance is zeroed before weighing something.

Preparing specimens for
 pressure bomb measurements

Before the lab groups were able to use the pressure bombs, samples of our study species in the greenhouse experiment were extracted and placed in a plastic bag inside a cooler until needed.  The cut end of the specimen was placed inside the narrow chamber; this required patience to guarantee that the cut end was exposed on the other side of the chamber.   While one person took charge of the pressure dial for recording the measurements, the other person ensured that the rate valve was never closed completely and controlled the arrow dial while observing the pressurized specimen.  In addition, safety was stressed during this experiment.  When using the pressure bomb, all students had to wear goggles for protection.

The final part of collecting sample data on both machines was practice for our next lab, where we will be using the plants that we have been growing throughout the semester.  Prior knowledge of using these machines in this lab session increases the accuracy of data collection for our greenhouse experiment next week.

For more information on the LICOR-6400:  http://hydrology1.nmsu.edu/teaching/soil698/student_material/photosynthesis/6400.html

For more information on the Scholander pressure bomb:  http://www.pmsinstrument.com/resources/making-the-measurement-of-the-plant-sample

Written by:  Danny Dlugos

                    Jaylan Craig

Herbarium voucher specimens

Today the JCU Plant Ecology class prepared voucher specimens collected on 5 September 2013 at the Blanche Novak Sanctuary in Portage County, OH.  The specimens were pressed on 5 September and we mounted them on 24 October.  Typically voucher specimens provide presence/absence data which is collected to measure plant community richness, diversity and evenness.  These voucher specimens are intended to identify species and provide locality information for specimens.  Ideally plant voucher specimens are posed to show distinguishing features like leaves, flowers, fruits, stems and roots for ease of identification.  As wise person once said, “Mounting and pressing plant specimens is an art form.”

Proper plant mounting techniques.

The plant specimens were previously pressed to eliminate moisture and pose them for mounting.  To mount the specimens we glued them to acid free archival paper.  Gummed linen mounting strips were also used to secure larger plants with woody stems.  This acid-free paper will help to preserve the specimens as it will prevent the plants from becoming discolored.  Finally we labeled each specimen with the scientific name (Family, Genus species), collection information (like locality data – both geographic and plant community information) and the collectors.

Some common species found by the class were: Horsetail (Equisetum arvense), bird’s foot trefoil (Lotus corniculatus), various goldenrods (Solidago sp.), Queen Anne’s Lace (Daucus carota), narrowleaf plantain (Plantago lanceolata), and the New England Aster (which has had a recent change in classification from Aster novae-angliae to Symphyotrichum novae-angliae).  We also had 3 unknown grass and 9 unknown plants and 3 unknown goldenrod species.  These species may be able to be identified in the future and others may undergo changes in classification.

L: Horsetail (Equisetum arvense).  R: Queen Anne's Lace (Daucus carota).

Three unknown Solidago sp.

This is an important exercise because there are often changes in the taxonomic nomenclature of plants.  Voucher specimens can provide a sort of history of scientific names.  As such, having a record of past and present scientific names of a plant can be important in linking these changes to previous research.  Species can be compared, potentially split or reverted to a previous taxonomic classification.   

New England Aster (recent change in classification from Aster novae-angliae to Symphyotrichum novae-angliae).

If a location is sampled repeatedly over time, some questions can be answered about the richness, evenness and diversity of the plant community like:

1      Which plants make up the community?  (presence/absence data)

2      In what abundance?  (plant species richness)

3      Which plants are dominant in the area?  (plant species evenness and diversity)

New invasions of native or invasive plants or disappearances of rare species can also be observed.  This data can then be useful to land managers to create a management strategy tailored to the changing plant community to protect the rare species or defend against the invasive species.

For more information on plants native to Ohio and voucher specimens:

USDA plant database:

http://plants.usda.gov/java/

More information on plant voucher specimens:

http://www.ipaw.org/mapping/voucherhandout.pdf

http://www.flmnh.ufl.edu/herbarium/voucher.htm

Authored by:

Josh Traub

Angelica Bradac

Alex Cameron

Measuring Forest Community Composition

View of Aurora Sanctuary Forest

Birds play a crucial role in the life cycle of many plants and animals. Birds often are involved in the distribution of plant seeds to distant lands. Anyone who has had bird feces on their car can give evidence that their diet is chiefly composed of seeds. Also necessary in the bird’s lifecycle is a place to live and rest. The Cleveland Audubon Aurora Sanctuary is an ideal area for this and as such is home to thousands of trees in which the birds may roost. This forest is mostly comprised of mature hardwood trees but evidence of prior farming lives on in the form of mature pines which were planted by farmers as wind breaks.

Trees come in lots of shapes and sizes

When looking at a forest from a scientist perspective, it is important to assess the plant community composition. This is helpful in understanding how diverse or even a forest is and also how species rich it is. Data can be compiled through many methods such as the Point Centered Quarter (PCQ) Method. It involves compiling tree data (diameter and species) of certain trees that fall into a particular point along a quartered transect. This method is relatively fast and easy to conduct due to the fact that not all trees are measured in the plot. Also, since only certain trees are measured, randomization can be accounted for. Large trees, which were specified by having a diameter greater than 20 centimeters at breast height (dbh = diameter at breast height) and small trees, less than 20 cm dbh yet bigger than 2.0 cm dbh, were located and measured. It is important to measure both large and small trees in a forest in order to be able to determine how plant community composition changes over time.

Measuring distance from the point to the tree

The tools needs for the PCQ Method are a specific type of measuring tape called a DBH tape. This tape is dual sided, while one side is used to measure distance in meters, the reverse side measures circumference and converts the diameter in centimeters. The distance taken between quarters was  determined using a random numbers table. The random numbers table gave a number of paces taken in between each quarter. Once the appropriate amount of paces were taken, a plot was divided into four transects.

The DBH tape converts circumference into diameter in cm.

From this point, the closest small and large trees in each of the four transects were measured. Both the distance from the origin of the quarter to the tree, as well as the diameter of the tree was recorded. After measuring the closest small and large tree in each quarter, the species was identified and recorded. Most species were able to be identified by their leaves using field guides. Some species were identified with a dichotomous key in the lab afterwards.

All data is carefully recorded

Red Maple: leaves have finely serrated leaf edges
In the fall, they turn bright red

Sugar Maple: leaves have 5-points with coarse serration
In the fall, they turn yellow

PawPaw Leaf

Tuliptree Leaf

Hawthorn Leaf

For more information on the species found, click on their name below:

Acer rubrum (Red Maple)

Acer saccharum (Sugar Maple)

Asimina triloba (PawPaw)

Carya ovata (Shagbark Hickory)

Carya cordiformis (Bitternut Hickory)

Crataegus sp. (Hawthorn)
Fagus grandifolia (American Beech)
Fraxinus americana (White Ash)

Lindera benzoin (Northern Spicebush)

Liriodendron tulipifera (Tuliptree)

Pinus strobus (White Pine)

Prunus serotina (Black Cherry)
Quercus alba (White Oak)
Quercus rubra (Red Oak)

Ulmus americana (American Elm)

For More Information on the Aurora Sanctuary:

Cleveland Audubon Aurora Sanctuary
  - Be careful hiking in this area after it has rained, the wooden bridges and stairs can be slippery -
  - Also be aware that a permit is needed for work / hiking off of the trail-


 
By: Lindsay, Jay, and Maria

Mentor Headlands State Nature Preserve

On Thursday October 3, 2013, John Carroll Plant Ecology Class BL 435/535 went to Mentor Headlands. There were two types of parks present there, The State Nature Preserve and the State Park. State nature preserves are a type of preserve that is used for conservatory purposes. In this section there were more grasses present and a small sandy area. The state parks are used more for recreation use and are not as strict as preserves. There was a much larger sandy area compared to the preserve and not much grass area present. The State Nature Preserve is a part of the buckeye trail which is about 1,444 miles long that loops around Ohio. There is a light blue rectangle on a tree at the beginning of the trail to indicate it is a part of the Buckeye Trail. 

This park is the longest stretch of undeveloped land on the shore of Lake Erie at one mile long in Ohio. The rest of the land is development of houses and industries. The largest area along Lake Erie of undeveloped land is in Pennsylvania which is 1.5 miles long at Erie Bluffs Park. Lake Erie is the shallowest of all the Great lakes with all of it above sea level. There are many large industrial cities and suburban areas along the shoreline which create many pollutants. Since Lake Erie is so shallow these pollutants from the cities create run off to the lake which can have harmful effects. Before the Clean Water Act of 1972, most of the pollutants were from industries, now pollutants are coming from agriculture especially from fertilizers. Fertilizers create a lot of nutrients to become available in the lake and this generates the problem of cyanobacteria blooms.
 

Have you ever wondered why certain plants are found where they are in the environment and why? If you have, you are not alone. The understanding of the dynamics of plant community composition has puzzled ecologists. Plant communities are driven by succession which is a directional change in species composition.  Succession starts with a disturbance: anything that leads to the destruction of biomass. Wind, fire, water, wave action and human disturbance are a few examples of disturbance. The scale of the disturbance is important because it can impact the degree of succession that follows. Large-scale disturbances lead to primary succession, meaning there is no seed bank and the plant community starts from ground zero. When disturbance happens on a smaller scale, secondary succession follows. For example, when an agricultural field is no longer planted it will begin to return to its original plant composition.

Henry Gleason revolutionized the understanding of dynamics of plant communities. The species found in an area are determined by species characteristics that match well with abiotic factors of the environment. For example, pioneer species that are adapted to high disturbance environments will be found in areas of primary succession.

                      

Area under constant disturbance.

The edge of succession is where there is constant disturbance.  At the Headlands Dunes State Nature Preserve (HDSNP), the edge of succession is the beach where the constant wave action and the advancement of ice when the lake freezes which prevent any vegetation from establishing near the water’s edge.  This prevents most species from colonizing and as such disturbance tolerant species are common.  These pioneer species are typically small, annual plants with fine root systems to hold soil.  Some plants have developed distinct strategies for seed dispersal.  For example, the cocklebur, Xanthium strumarium, has hooked fruits to attach to animal fur and the sea rocket, Cakile edentula, loses its seeds when lightly touched.

Left: cocklebur. Right: searocket.

Further from the beach, there is less disturbance and grasses are common like beach grass, Ammophila breviligulata, switch grass, Panicum virgatum, and sand dropseed, Sporobolus cryptandrus.  Grasses have long root systems to hold sand together to absorb water deeper into the ground.  These grasses also generally have a high salt tolerance.  Eventually plants begin to change the environment.  As distance from the disturbance increases, the thickness of plants also increases.  These thicker grasses bring an increase in organic matter to the environment which increases nutrient availability so other species are able to establish like mosses.  The grasses are a natural control for erosion and if there is no disturbance for long enough, trees will begin to colonize the area.  In an area of less disturbance, trees begin to take root like: the wafer ash, Ptelea trifoliata, and the black oak, Quercus velutina.

Left: sand dropseed.  Center: switchgrass.  Right: black oak

                

Environments like the Mentor Headlands can provide valuable data to form a chronosequence. Looking at the edge of the lake and moving back, one can see the different levels of succession. One can begin to understand which plants facilitate the succession of more emergent vegetation by how they change certain aspects of the environment, i.e. soil nutrient availability.  However, when this is done, the assumption is being made that environmental conditions have not changed which might not be the case. Regardless, Mentor Headlands provides us with a valuable picture of the process of succession occurring along the coastline of Lake Erie.

Related links:

Headlands Beach State Park:

http://parks.ohiodnr.gov/headlandsbeach

Headlands Dunes State Nature Preserve:

http://ohiodnr.com/location/dnap/headlands/tabid/892/Default.aspx

More information on dune plant succession:

http://www.landforms.eu/Lothian/dune%20succession.htm

More information on the Buckeye Trail:

http://www.buckeyetrail.org/