ESCI 407/507: Forest Ecology

Spring 2024

Last updated: 5/17/2024

2013 Note: Need to update all datasheets and excel files to include Vine maple as an understory plant; this species occurs in the oldgrowth stand, but not at Blanchard; this needs to be includes in the total shrub tally.  Current shrub tally in all excel files is incomplete and hence results in 2nd growth showing more shrub than OG.

 

 

 

Lab #6: A Comparison of the Structure and Composition of an Old-growth and Second-growth Stand.

Objective: The objective of this lab is to compare the structure and composition of an Old-growth stand to the Second-growth stand you sampled last week. We will be using the same sampling technique that we used last week. I hope that we will be able to collect data from the old-growth stand from a total of two sample plots (one plot each day). I will also provide you with data from last years class for two additional plots from this old-growth stand.  You will compare these data to the data from the four INTERIOR plots from last week (three interior plots from last year and one interior plots from this year at the second-growth site). As with the previous lab report, these plots are the basic unit of observation for our analysis. You will collect data using the same data sheets as last week. Get your data to us in the same format as last week.  Use the “blank.xls” template that we used last week. 

Our analysis will be based on data from 21 interior plots from Blanchard Mt. (1 collected this year,  from 2023 and 19 from previous years) and 21 plots from the old-growth stand (4 from this year and 17 from previous years). 

Methodology: Same as last week. Take a look at the web page for last week's lab to refresh your memory. You have experience now so we should be able to work a little faster this week. This will be essential since our travel time is a bit longer. We will be heading up to milepost 44 on the Mt. Baker Highway.  It is unlikely that we will be able to get back to the Environmental Studies building by 5:00 pm.  Plan accordingly.

Data Analysis: As in your previous report, these data present a very large number of potential comparisons. Take a look at the paper by Franklin et al. (1981. US Forest Service Publication, GTR-PNW-118) and another by Hansen et al. (1991. Bioscience 41:382-392) (See links to online versions of these papers below). These papers will provide some background and a starting point for your analysis. To make your lives simpler, you can limit yourselves to the analyses suggested below. More creative analyses will be rewarded!  I would encourage you to use the spreadsheets I gave you last week as templates for the tables listed below.  The only thing that is new for this week’s analysis is that we will be comparing CWD volumes for the second-growth and old-growth stands.

 

Table 1: For all trees >10cm DBH, calculate the mean and standard deviation (among plots) of tree density (stems/ha) for the following categories:

a. all species
b. Douglas Fir
c. Western Red Cedar
d. Hemlock
e. Pacific Silver Fir
f. any other species encountered

Calculate separate values for the Old-growth and the Second-growth stands. Compare these means using a two-sample t-test or single factor ANOVA in Excel, R or some other software package.

 

Table 2: For all trees >10cm DBH, calculate the mean and standard deviation (among plots) of basal area (m2/ha) for the following categories:

a. all species
b. Douglas Fir
c. Western Red Cedar
d. Hemlock
e. Pacific Silver Fir
f. any other species encountered

Calculate separate values for the Old-growth and the Second-growth stands. Compare these means using a two-sample t-test or single factor ANOVA in Excel, R or some other software package.

 

Figure 1: A histogram showing the tree size class distribution. Calculate the mean stem density (stems/ha) for each size class. You should include a pair of bars for each size class including saplings.  (saplings, 10-20, 20-30, 30-40, 40-50, 50-75, 75-100, 100-150...). One bar in each pair presents mean values for the Old-growth plots and the other presents the mean values for the Second-growth plots. If you want to get fancy, you can try to include the 95% confidence interval for each of these mean values. For this figure, we lump all tree species together. We don't keep track of each species.

 

Table 3: Understory composition. Mean and standard deviation (among plots) for the following categories:

a. Total percent cover of all plants
b. Percent cover for all shrub species
c. Percent cover for all herbaceous species.

Calculate separate values for the Old-growth and Second-growth plots. Compare these means using a two-sample t-test or single factor ANOVA in Excel, R or some other software package.

 

Table 4: Snags. Mean and standard deviation (among plots) of snag density (stems/ha) and snag basal area (m2/ha). Note that this is based on snags with a minimum height of 1.37m. This means that snags had to be at least "breast height" in order to count them. Coarse Woody Debris (CWD) Volume (m3/ha).  Calculate separate values for the Old-growth and Second-growth plots. Compare these means using a two-sample t-test or single factor ANOVA in Excel, R or some other software package.

 

Figure 2 and 3: Decay Class of Snags and CWD:  I’d like you to prepare figures that illustrate the frequency distribution of Snags and CWD by decay class.  The X-axis for both of these graphs will be decay stage/class and the X-axis Y-axis (typo corrected 5/18; 10:00AM) will be the percentage of pieces in each decay class.  Each decay class will have two bars; one showing the % of pieces in that decay class for the Second-growth stand and the other bar showing the % of pieces in that decay class for the Old-growth stand.  Figure 2 will present the data for Snags and Figure 3 will present the data for CWD.  Note that for CWD the Decay Classes go from I to V; for snags, the Decay Stages go from I to IX.  Note that I have not included a template for producing these figures.  By this point in the quarter, I feel that you should have enough experience to figure this out for yourselves.

Worksheet Templates:

forest_data_anal_template.xls

 These files have been updated for 2024 (5/13/24)!!
og_table1.xls  add note to all figure/table legends RE the number of plots used in the analysis
og_table2.xls
og_table3.xls
og_table4.xls 

og_figure1.xls

All datasets (completed version of the “forest data anal template.xls” file) must be turned in by NOON on the day after your lab. If datasets are incomplete or late, EVERY MEMBER OF THE GROUP WILL RECEIVE A 5% PENALTY ON THEIR LAB REPORT. No exceptions. No excuses.

2011 Data: All datasets must be received by me in complete form by noon on the day following your lab.  Failure to turn your data in on time will result in a penalty of one full letter grade on your lab report for EVERYONE in your group.  There are no exceptions and no excuses.  I don’t care whose “fault” it is.  It is the collective responsibility of each member of each group to see to it that this gets done.  This is a simple task.  See to it that it gets done!

2024 Data: I’ll post these below as soon as I receive them. Please contact me ASAP if you see any problems with these datasets. I took a quick look and I did not see any obvious issues.

og_wed_plot1_2024.xlsx (Data looks good, posted 5/16)

og_wed_plot2_2024.xlsx (Data looks good, posted 5/16)

og_fri_plot1_2024.xlsx (Data looks good, posted 5/17)

og_fri_plot2_2024.xlsx (We were short-handed on Friday so only got one plot done. I’m substituting data from a plot collected in 2023 here, posted 5/17)

 

OG_tues_2016_alexis.xlsx  (all looks OK)

OG_tues_2016_Clay.xls  (all looks OK)

OG_wed_2016_Brett.xls  (all OK)

OG_wed_2016_Alyssa.xls   (all looks OK)

…..

OG_wed_RL_2015.xls

OG_Wed_MM_2015.xls

OG_thurs_EP_2015.xls

OG_thurs_JB_2015.xls

2013 Data:  Please contact me ASAP if you see any problems with these datasets other than those noted below.

og_wed_lauren2013.xls

og_wed_travis2013.xls

og_Thurs_jamie_2013.xls

og_thurs_haley_2013.xls

OG_Mon_group1_2012.xlsx (Note: See my note on the raw tree page.  I feel that the species ID on two trees was incorrect so I made a change)

OG_Mon_group2_2012.xlsx (Note: See my note on the raw snags page.  We need clarification of this ASAP)

OG_Tues_group1_2012.xlsx (Note: See my note on the raw tree page.  I feel that the species ID on one tree was incorrect so I made a change)

OG_Tues_Group2_2012.xlsx

Due Date for Lab Reports: Lab reports are due by 5PM on May 22 (for the Wednesday lab section) or 5PM on May 24 (for the Friday lab section). As on all lab reports, there is a 5% per day penalty for turning in your report late. Be sure to check the Lab Index page for information on the proper format, organization and grading criteria for your lab reports.

 

Literature Cited on this web page:

Franklin, J.F. et al. 1981. Ecological characteristics of old-growth Douglas-fir forests. USDA Forest Service, Pacific Northwest Forest and Range Experiment Station Publication, GTR-PNW-118, 48 pages. (This paper is available online in two .pdf files:
http://www.fs.fed.us/pnw/pubs/gtr118part1.pdf 
http://www.fs.fed.us/pnw/pubs/118part2.pdf

Hansen, A.J., T.A. Spies, F.J. Swanson and J.L. Ohmann 1991. Conserving biodiversity in managed forests. Bioscience 41:382-392.  . (Click here to view and print this document through JSTORS) 

And just for fun:

Jones, I.R. and E. Allen.  2002. Detection of large woody debris accumulations in old-growth forests using sonic wave collection.  Transactions of the Important Tree Scientists 120(2):201-209.  Tree in the woods.pdf

 

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