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State of the forest, 2016

General ecology (EES-152) students have finished resurveying a portion of the Lehigh Experimental Forest, with the goal of assessing changes in tree growth, mortality, and recruitment since 2013. A total of 690 trees were measured from across the forest, representing more than a 1/4 of all trees. In the three years since 2013, 70 of these 690 trees have died and only three new trees have established in the study area.  Data for the dominant tree species are shown in the plot below.

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Tree abundance, mortality, recruitment, and growth rates in the Lehigh University Experimental Forest, 2013-2016. Relative frequency data are from 2013 (M. Spicer, MS thesis 2014) and indicate the percent of each species present (based on a total of 690 trees). Total mortality and recruitment across the time period are shown as percentages. The average increase in basal area of individuals of each species is shown, with the mean value for all species indicated with the vertical dashed line. Total change in basal area for each species, incorporating mortality losses and basal-area gains, is also shown.

We will use these data to discuss the processes controlling forest dynamics as the semester progresses.  However, for now, students should answer the following questions:

  1. The dbh measurements were converted into estimates of area, assuming that each tree was a perfect circle in cross-section. Why do you think basal area was used to compare growth rates among the different species? Why was this expressed as the average change in basal area per tree? What factors might have caused the observed differences in radial growth among species?
  2. What does the pattern of mortality and recruitment suggest about the future of the Lehigh Experimental Forest? What factors might have caused the differences in mortality among species during these two years? What factors might be contributing to the lack of new tree recruitment in the forest?
  3. Assuming the rates of total tree recruitment and mortality are representative of future years, when will there be no trees left in this forest?  In 2013, there were ~2000 trees in the forest. Show your work and describe how you arrived at your estimate.  Do you think it is likely that the trees will really be gone by this time?  Why or why not?
  4. Which species had both very high mortality and very low growth during this time period? Do some research on current threats to this particular species, and summarize your research in a short paragraph.

Camera traps in the Lehigh Forest, Fall 2015

General ecology students installed two camera traps in the Lehigh University Experimental Forest.  The image tally after recording for about six weeks: one fox, one raccoon, one chipmunk, 2 domestic cats, 18 squirrels, and 38 deer.  Some highlights…

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Female white-tailed deer searching for vegetation on Halloween.

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A second female white-tailed deer rechecking the area.

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Male white-tailed deer a few days earlier

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“Fox went out on a chilly night…”

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Rocky

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Yes, you can see a black cat at night.

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Must be some native vegetation back here somewhere.

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A deer can’t live on Japanese Barberry alone.

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Wow.

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There has not been any tree recruitment here for decades.

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Out for a noon-time stroll.  Looking for lunch.

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Another picture of the same male.

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An ecosystem modeller with the EES-80 class!

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Still hungry.

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Nope, no native birds here.

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Not a very large forest fragment.

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Time for a selfie.

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Captured on the way to download the camera traps!

First resurvey of the Lehigh Experimental Forest

Growth, mortality, and recruitment (shown in red) of dominant tree species in the Lehigh Experimental Forest from 2013-2015. Average tree size and numbers of indivduals included in the survey shown in blue. We will use these data as a springboard for discussion of processes controlling forest dynamics.

Growth, mortality, and recruitment (shown in red) of dominant tree species in the Lehigh Experimental Forest from 2013-2015. Average tree size and numbers of indivduals included in the survey shown in blue.

Inventory of the forest.

Taking inventory of the forest, 2015.

Students in general ecology (EES-152) resurveyed a portion of the Lehigh Experimental Forest, to assess changes in tree growth, mortality, and recruitment since 2013.  No new trees greater than 1.4 m high were documented, and both growth and mortality varied considerably among species.  Over 500 trees were measured, and the plot above shows data for the dominant trees (those with >15 individuals included in the survey).

We will use these data as a springboard for discussion of processes controlling forest dynamics, and will examine some of these issues in greater depth during our discussions and future lab activities.

 

For now, students should answer the following questions:

1. The dbh measurements were converted into estimates of area, assuming that each tree was a perfect circle in cross-section. Why do you think basal area was used to compare growth among the different species? Why was this expressed as the average change in basal area per tree, as opposed to the total change in basal area for all individuals of the species? What factors might have caused the observed differences in radial growth among species?

2.  What does the pattern of mortality and recruitment suggest about the future of the Lehigh Experimental Forest? What factors might have caused the differences in mortality among species during these two years? What factors might be contributing to the lack of new tree recruitment in the forest?

3.  Which species had both very high mortality and very low growth during this time period? Do some research on current threats to this particular species, and summarize your research in a short paragraph.

150 things that make Lehigh University what it is today

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As part of the Lehigh University sesquicentennial celebration, the University is rolling out a list of some of the things that have helped Lehigh become such an interesting and unique place.

The “lost” forest made the list at #93!

Some of the fun that Lehigh students have in this historically unique forest is highlighted here and here.

Camera traps, June 2014

Velvet-covered antlers in the Lehigh Experimental Forest.

Velvet-covered antlers in the Lehigh Experimental Forest.

More data from the Lehigh Experimental Forest camera traps. Our complete list of “trapped” species since October now includes:

  • Buteo jamaicensis (Red-tailed hawk)
  • Canis lupus familiaris (Domestic dog)
  • Felis catus (Domestic cat)
  • Homo sapiens (Human)
  • Marmota monax (groundhog)
  • Meleagris gallopavo (wild turkey)
  • Odocoileus virginianus (White-tailed deer)
  • Procyon lotor (Raccoon)
  • Sciurus carolinensis (Gray squirrel)
  • Sylvilagus floridanus (Eastern cottontail)
  • Tamias striatus (Eastern chipmunk)
  • Turdus migratorius (American Robin)
  • Vulpes vulpes (Red fox)

A few highlights from the two video cameras (wild turkey at the end!):

 

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