Lab4-FVSIntro

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Dec 6, 2023

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ESPM 185: Applied Forest Ecology Lab 4: Intro to FVS and Stand Density Index Overview In the early 1980s, Dr. Thomas Veblen installed several permanent forest plots in subalpine forests in the Colorado Front Range. The goal was to establish a set of long-term forest plots to monitor tree populations and stand dynamics over time. When the plots were installed, all living and standing dead trees were permanently tagged, and the following was measured for all live and dead trees ≥1.5 inches dbh: (1) species, (2) dbh, and (3) status (live or dead). Additionally, all juvenile trees (< 1.5 inches dbh) within the plots were counted by species. For more details see Veblen (1986). In 2016, a complete re-measurement was performed, including new counts of juvenile trees and tagging of ingrowth. In this lab, you will work with data from the one of the permanent plots (MRS1), a lodgepole pine-dominated stand that established following a stand replacing fire in ca. 1890. The plot is about 0.28 acres and contains more than 800 tagged trees which have been monitored for the past 30+ years. Broadly, this lab is intended to build your understanding of stand development processes in forests characterized by infrequent, high-severity fire regimes and introduce you to the Forest Vegetation Simulator (FVS) and its potential uses in silviculture. Learning objectives Upon successful completion, students will demonstrate the ability to:  Discuss how stand density influences tree growth  Calculate and correctly interpret the stand density index (SDI)  Discuss why SDI is useful metric for silviculture  Predict changes in stand structure  Use Forest Vegetation Simulator to: o complete a basic stand projection o generate figures o interpret basic output Instructions Follow the instructions below to answer the lab questions. Record your answers in the corresponding Canvas quiz assignment. Stand development Stand density is an important driver of tree growth, mortality, and regeneration. The stand density index (SDI) is a relative expression of stand density based on the relationship between average tree size and the number of trees per unit area. SDI a useful measure to assess competitive interactions between individual trees in a stand. 1

For even aged, single species stands, SDI can be quantified as follows: SDI = TPA ( D q 10 ) 1.6 Where:  TPA = trees pre acre  D q = quadratic mean diameter (in inches) The quadratic mean diameter can be quantified as follows: QMD = √ ∑ D i 2 n D i = the diameter of tree I n = the number of trees Part I: Summarizing stand structure data and projecting change Table 1 below displays a subset of the data from the MRS1 plot. This subset corresponds to an area of a ca. 1/100 th of an acre (or about 3.5% of the total plot area). Use this data to characterize stand structure in 1982 and make an educated guess about how stand structure will change over the next 34 years. 2 Question 1 : Based on the data in Table 1, what is the estimated stand density in trees per acre? (3 pts) Question 2 : Based on the data in Table 1, what is the estimated quadratic mean diameter (QMD) in inches? (4 pts) Question 3: Based on the data in Table 1, what is the stand density index? (4 pts) Question 4: Based on the stand density index and Figure 1, what is the approximate volume of this stand? (3 ts) A. 40-400 B. 600-1500 C. 1800-2800 D. 3500-4800 Question 5: Based on the stand density index and Figure 1, how tall on average are the trees in this stand? (3 pts) A. 20 f B. 40 f C. 60 f D. 80 f Question 6 : What do you think the stand structure will look like 34 years later when the remeasurement was performed? (Hint: Fig. 1 may be helpful). Specifically, how do you expect live tree density and QMD of live trees to change? (5 pts)

Table 1: A subset of the tree inventory data collected from MRS1 in 1982. Data represents a subarea of about 1/100 th of an acre nested within the larger plot. For species, PICO is lodgepole pine and PIFL5 is limber pine. Stand ID Tree ID Species DBH (in) MRS1-1982 1 PICO 2.4 MRS1-1982 2 PICO 3.5 MRS1-1982 3 PICO 3.1 MRS1-1982 4 PICO 3.9 MRS1-1982 5 PICO 2.4 MRS1-1982 6 PICO 3.5 MRS1-1982 7 PICO 2 MRS1-1982 8 PICO 2.8 MRS1-1982 9 PICO 2.4 MRS1-1982 10 PICO 2.4 MRS1-1982 11 PICO 4.3 MRS1-1982 12 PICO 2 MRS1-1982 13 PICO 4.3 MRS1-1982 14 PICO 3.1 MRS1-1982 15 PICO 4.7 MRS1-1982 16 PICO 2.4 MRS1-1982 17 PICO 3.1 MRS1-1982 18 PICO 3.1 MRS1-1982 19 PICO 3.1 MRS1-1982 20 PICO 4.7 MRS1-1982 21 PICO 2.4 MRS1-1982 22 PICO 2 MRS1-1982 23 PICO 2 MRS1-1982 24 PICO 3.9 MRS1-1982 25 PICO 3.1 MRS1-1982 26 PICO 2 MRS1-1982 27 PICO 4.3 MRS1-1982 28 PICO 3.9 MRS1-1982 29 PICO 5.1 MRS1-1982 30 PICO 2.8 MRS1-1983 31 PICO 2.4 MRS1-1982 32 PICO 2 MRS1-1982 33 PICO 3.9 MRS1-1982 34 PICO 2.4 MRS1-1982 35 PICO 2.8 MRS1-1982 36 PICO 0.1 3

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Figure 1: Density management diagram for lodgepole pine, modified from McCarter and Long (1986). Reminder, the x and y axes are plotted along the log scale (which is why 50 to 1000 (950 TPA difference) are are farther apart then 1000 to 5000 (4000 TPA difference). If you would like to see use the tickmarks shown below to better plot TPA, you can see the table at the bottom of this assignment. 4

Part II: Using FVS to characterize stand structure In Part II, of this lab you will perform a basic FVS simulation using data from MRS1. You will compare data collected in the 1982 inventory (Stand ID MRS1-1982) with data collected during the 2016 inventory (Stand ID MRS1-2016). You will also compare what FVS-simulated stand structure and composition in 2016 based on the data collected in 1982. Directions 1. Open FVS 2. Set up a new FVS project o From the main menu, navigate to the Manage Projects tab.  From the secondary menu, navigate to the Manage project subtab. o In the New project title text box enter “Lab4-[LastName]-[FirstName]” o In the Select project pull down window, select your new project and click the Open selected project button. 3. Set up a new FVS project o Download the file FVS_MRS1.xlsx file from the Canvas Lab 4 assignment page o From the main menu, navigate to the Manage Projects tab.  From the secondary menu, navigate to the Import input Data tab.  From the tertiary menu, navigate to the Upload inventory database subtab. o Under the Step 1: Upload FVS-Ready database (.accdb, .mdb, .db (SQLite3), .sqlite, .xlsx, or .zip that contains one of these) prompt and click the Browse... button and select the FVS_MRS1.xlsx file you have just downloaded o Under the Step 2: Following upload, you must do one of the following click the Install uploaded database button. Note you see the following message: 2. Set up the simulation o From the main menu, navigate to the Simulate tab.  From the secondary menu, navigate to the Stands subtab. o Change the Run title to No Action. o In the Groups selection box on the right, highlight All_Stands o In the stand selection box on the right, highlight both MRS1-1982 and MRS1-2016 then click the Add selected stands button. 5

 From the secondary menu, navigate to the Time subtab o Set the common starting year to 2016 and the common ending year to 2100 3. Select desired model outputs o From the main menu, navigate to the Simulate tab.  From the secondary menu, click the Select Outputs subtab o Check the box next Tree lists to request the information needed to make stand and stock tables 4. Run the simulation o From the main menu, navigate to the Simulate tab.  From the secondary menu, click the *Run* subtab o Enter Base into the MgmtID (4 chars) text box o Click the Save and Run button o Check to see if there were any errors in simulation.  After running the simulation scroll to the bottom of the page, and locate the text that says “FVS error scan:”. Any errors will print bellow this text. Part III: Interpreting tabular outputs from FVS 1. Characterize the stand structure in 1982 o From the main menu, navigate to the View Outputs tab  From the secondary menu on the left, click the Load subtab  In the Runs to consider selection box, select the No Action option  In the Database tables to consider box, select the FVS_Summary2 option (located under the header ---Stand-level tables----). This will open a table containing stand level summary statistics, including the year, stand density, QMD, SDI, removals, and many other useful measures. 6 Question 7 : True or False – The following graph appears after running your simulation. (2 pts) . Question 8 : What error message (if any) do you get after running your simulation? (2 pts) . S

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 Use the Describe tables pull down menu to familiarize yourself with the table variables and their definitions. These definitions will provide most of the information you need to select the appropriate variables to describe your stand,  From the secondary menu on the left, click the Explore subtab  From the tertiary menu on the right, click the Tables subtab o In the Stands box, select MRS1-1982 and MRS1-2016 o In the Year box, select 1982 and 2016 Part IV: Creating basic figures with FVS FVS generates a stand and stock table (StdStk), which reports trees per acre, basal area, and volumes by species and diameter class. We will use this table to create a simple diameter distribution graph. 1. Create a diameter distribution that displays the density of trees in 1-inch DBH classes o From the main menu, navigate to the View Outputs tab  From the secondary menu on the left, click the Load subtab  In the Runs to consider selection box, select the No Action run  Set the DBH class size box to 1, then click the Rebuild StdStk button rebuild the stand and stock table using 1” class sizes  In the Database tables to consider box, select the StdStk option (located under the header ---Diameter-class tables----) to obtain the stand and stock table  From the secondary menu on the left, click the Explore subtab o In the left pane, Select run titles box, select the name of your run ( i.e., No Action ) o In the Stands box, select both MRS1-1982 and MRS1-2016 o In the MgmtID box, select the Base o In the Year box, select only 2016 7 Question 9: In the FVS Summary 2 table, what does the SDI variable describe? In other words, what does SDI stand for and provide a brief (1-2 sentence) description of what SDI means. (2 pts) Question 10: In the FVS Summary 2 table, what does the CCF variable describe? In other words, what does CCF stand for and provide a brief (1-2 sentence) description of what CCF means. (2 pts) Question 11 : In 1982, what was the stand's basal area? Enter your answer in square feet per acre (the default values output by FVS). (3 pts) Question 12 : Based on the 1982 inventory data, what did FVS simulate that the basal area of the stand would be in 2016? Enter your answer in square feet per acre. (3 pts) Question 13 : What was the live basal area measured during the 2016 inventory? Was it greater than, less than, or similar to the live basal area FVS simulated to be present in 2016, based on the 1982 inventory. (4 pts)

o In the Species box, select ABLA (subalpine fir – Ab ies la siocarpa) PICO (lodgepole – Pi nus co ntorta, PIFL2 (limber pine – Pi nus f exilis) and POTR5 (aspen – Po pulus tr emuloides) o In the DBHClasses box, select all values BUT All (i.e., 1 , 2 , 3 … 14 ) o From the tertiary menu on the right, click the Graphs subtab  Make the following changes to the graphing options:  Type : bar  Y-axis : LiveTpa  X-axis : DBHclass  Horizonal facet : RunTitle  Vertical facet : StandID  Plot-by code : Species  X-label : DBH class (in)  Y-label : Live trees per acre  Now slightly modify your graph by selecting both 1982 and 2016 as years and instead of having the horizontal facet be RunTitle, change it to Year References McCarter, J. B., and J. N. Long. 1986. A Lodgepole Pine Density Management Diagram. Western Journal of Applied Forestry 1:6–11. Veblen, T. T. 1986. Age and size structure of subalpine forests in the Colorado Front Range. Bulletin of the Torrey Botanical Club:225–240 Interpreting log-scale Axes The SDI curves are plotted along a log-scale, which can sometimes makes it harder to quickly interpret. Here is a table that shows for a given TPA, the point along the x-axis the log of TPA would fall between 0 and 100 (if the tickmarks are evenly spaced, such as the very bottom and top ruler in Figure 1). Since figure 1 starts at 50 8 Question 14 : Upload your diameter distribution graphs. Make sure that your axes are labeled correctly! (6 pts) Question 15 : Based on the diameter distribution graphs from the 1982 and 2016 inventories (not FVS simulations), which of the following statements is true? (2 pts) a) The most frequently occurring species in 1982 was lodgepole pine, but by 2016 the stand composition had shifted so that limber pine was more common than lodgepole pine. b) The density of trees 3.5 – 4.5” increased from to 1982 to 2016. c) The density of aspen trees increased from to 1982 to 2016. d) The density of trees 1.5 - 2.5” decreased from to 1982 to 2016. Question 16: Were the actual changes in stand structure consistent or inconsistent with what you predicted in Question 6? (2 pts) Question 17: After exploring the FVS simulation outputs from the 1982 data for 2016 and comparing those outputs with the actual forest structure for 2016, how well do you think FVS performed? (1 pt)

TPA, then a TPA of 50 would be at 0 (i.e. the very start) and since the TPA ends at 5000, then the TPA would be at the 100 tick mark (the point at the very end). TPA log(TPA) Point Along Axis (if points were evenly spaced from 0-100) 50 1.699 0 65 1.813 5.7 80 1.903 10.2 100 2 15.1 200 2.301 30.1 300 2.477 38.9 400 2.602 45.2 500 2.699 50 750 2.875 58.8 1000 3 65.1 1500 3.176 73.9 2000 3.301 80.1 2500 3.398 85 3000 3.477 88.9 3500 3.544 92.3 4000 3.602 95.2 4500 3.653 97.7 5000 3.699 100 9

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