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/