ecological restoration (bio 409) dr. mcewan reference conditions

Ecological Restoration (BIO 409)Dr. McEwan

Reference Conditions

Concepts

Reference conditions: Ecological restoration implies activity that intends to drive a

degraded system toward a new, and better condition. But, what is (specifically) the objective? Reference ecosystem conditions are a set of traits that the restoration uses as a target for the restoration activity. Reference conditions can include:

1)Species composition2)Ecosystem structure3)Ecosystem dynamics4)Disturbance regime

Concepts

Reference conditions, Four general conditions:

Same timeSame place

Same timeDifferent place

Different timeDifferent place

Different timeSame place

Restorationists generally would try to get as much information as reasonably possible from all four of these conditions!

Same place – Same time

Drew Woods is a pretty good example of same place- same time. The site itself has many of the species of interest, has relatively good forest structure, and is true old-growth forest in most important ways. It also is being invaded by several plant species and has a big problem with edge effects. We could use the site itself to guide restoration here.

Same time – Different Place

Site for restoration, current condition. Target- condition in some other location, near the restoration site.

Tools: Taxonomy, create a species list. Quadrats to measure abundance patterns . Documentation of flood regime.

Same place – Different time

Site for restoration, current condition. Target- same location, in the past

Tools: Paleoecology…dendro,; pollen analysis; historical documents.

Different place – Different time

Griffith Woods is a pretty good example of different place- different time. There is no good local reference site. I used dendrochronology in an attempt to recreate historical conditions, but that can only provide information related to tree growth and ecosystem dynamics and disturbance. So the folks organizing this restoration were really looking at Midwestern savanna..

Brief introduction to the tree-ring methods for establishing reference conditions.

First- what is a tree ring?

-A record of tree growth, created by a tree’s seasonal access to resources and/or by cold weather.

- In temperate zones, it is warm and wet in the summer, cold in the winter. Trees have to shut down in winter or else they will be killed by freezing temperatures.

Temperature-derived tree rings:-In the summer, it is warm and wet, the trees grow rapidly.-In the autumn, temps drop, trees lose their leaves.-In the winter, freezing temps, the trees are “dormant”.

Summer Winter

Temperature-derived tree rings:- This process is recorded in the wood as an “annual ring”- “Annual”- because it happens every year.- This means we can date the trees with great accuracy

Summer Winter

One year

Winter Winter

Notice: Not all tree rings are the same size. Why?

In forests, tree-growth is growth controlled by:

a)Moisture availability: which is largely determined by precipitation (water) and temperature. This creates interannual variation. (high frequency changes)

b)Long-term climate trends, e.g., increasingly warmer temperatures over centuries. (low frequency patterns)

c)Changes in light availability associated with disturbance. “step-changes”

Tree-ring analysis can also be used to reconstruct fire history:

- When fire passes near a tree the heat kills the cambium.

- The tree closes the wound and therefore, encapsulates that injury in the wood. - The wounds are found in a tree-ring series, so they can be dated.

-Fire scars give information about the frequency of fires in the forest.

-If you collect many samples in a forest you can also reconstruct spatial patterns of fire.

-If have old trees, you can develop long histories.

For restoration

-We can use tree growth as an indirect measure of moisture availability, long-term climate, and forest disturbance.

-We can “monitor” these factors for the length of time the oldest trees in the forest are alive.

- We can reconstruct fires in the forest

-The only requirements: 1)the trees are old2)that the trees make annual rings3)that the authorities allow you to sample the trees.

For restoration

-We can use tree growth as an indirect measure of moisture availability, long-term climate, and forest disturbance.

-We can “monitor” these factors for the length of time the oldest trees in the forest are alive.

- We can reconstruct fires in the forest

-The only requirements: 1)the trees are old2)that the trees make annual rings3)that the authorities allow you to sample the trees.

Survey Notes as a tool in Ecological Restoration

When Anglo settlers were moving through North America they, for the first time, were creating ownership parcels. It was necessary to do this in order to sell property, etc. At that time, there were no GPS units, and very few signs of Anglo occupation (roads, etc). So the survey had to create notes based on distance and direction to landmarks.

Those landmarks were often ecological! Trees, streams, wetlands, etc.

Survey Notes as a tool in Ecological Restoration

Surveyor notes are held by many states. And, in some places you can actually look at images of the notes on microfilm.

The parcels become a vegetation survey. You can pull out the tree data and use it in analyses.

This provides a snap shot of the vegetation at the time of Euro-American settlement, and is a relatively well-respected method for creating a window into “intact” ecosystems.

http://academic.udayton.edu/RyanMcEwan/Pub/2005,McEwan_et_al,Witness,NAJ.pdf

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