Although everything in the Core Methods and design of a monitoring project is kept as simple and straightforward as possible, there are always questions about how things work in reality and cases where applying the method is not straightforward . These questions cover some of the more common questions about the processes and provide answers or resources to help clarify the murkiest parts.
Methods FAQ
Although everything in the Core Methods and design of a monitoring project is kept as simple and straightforward as possible, there are always questions about how things work in reality and cases where applying the method is not straightforward . These questions cover some of the more common questions about the processes and provide answers or resources to help clarify the murkiest parts.
Core and Supplemental Methods
Line-point intercept
Q: If we drop the pin flag on the edge of a rock and it touches another soil surface below, for instance “None-Cobble-Soil” or “Cheatgrass-Gravel-Embedded Litter,” do we record as such or do the rocks have to be listed as the surface level, writing just “None-Cobble” and “Cheatgrass-Gravel”?
A: When you have multiple options for the soil surface, call the first soil surface option and the more stable object as the soil surface. So in your example, I would say “None-Cobble” and “Cheatgrass-Gravel” because you 1) hit the rock fragment first and 2) the rock fragment is in theory more stable than soil or embedded litter. See Table 15 in the Monitoring Manual, 2nd Edition for a list of soil surface options.
Q: Should we be aiming to do the LPI sampling as quickly as the guy in the Jornada LPI demonstration video?
A: Yes. Extra deliberation at a point can lead to bias, as the wind may shift a blade (or several) of grass so that it’s now touching the drop pin or you may second guess yourself into an incorrect call. Be as complete and efficient as possible, but don’t pause for long periods.
Q: If the soil clump falls apart while we’re cutting it down for the soil stability test, we just get another one. Does this bias the sampling effort?
A: Sometimes the soil ped just breaks. If you are concerned about bias, move 30 cm down the transect and try again.
Q: If we hit a dead annual plant on our transect is it recorded as “standing dead” or “alive”?
A: If the annual grew this year then it is counted as a live hit. If it grew last year and it is still rooted, then it would be standing dead.Helpful hint: last year’s growth tends to be greyish material.
Q: We hit a dead yucca stalk lying along our transect. Is it woody litter or herbaceous litter?
A: The woody litter definition has been revised to include both woody and succulent litter > 5 mm in diameter. Herbaceous plants > 5 mm are still considered herbaceous litter.
Gap intercept
Q: Should we count last year’s annuals as a gap or as vegetation cover?
A: All rooted plant material is counted as canopy. The distinction between this year’s growth and last year’s growth only applies to whether or not you check “standing dead” box in the Line-point intercept form in the database.
Q: Why are the gap size classes set at 0-24, 25-50, 51-100, 101-200, and 201+ when the minimum standard gap is 20 cm? Shouldn’t the size classes read 0-19, 20-50, 51-100, 101-200, and 201+?
A: The minimum gap size is set to 20 centimeters in the field because observer error is reduced when you are measuring a 20 centimeter gap rather than trying use the 25 centimeter break as a gap threshold. However, gaps >25 centimeters tend to be more ecologically significant than gaps between 20 and 25 centimeters. Keep in mind that the thresholds used to analyze and interpret gap data are dependent on the question at hand, so more custom thresholds may be necessary in some analyses.
Q: Do large dead centers of grasses count as canopy?
A: Technically dead centers of grasses would be gap, however remember that in the standard method you need > 20 cm without canopy to record as a gap, so the chances of that counting as a recordable gap are slim. In the line-point intercept method, if you hit the dead center it would be recorded as soil rather than a basal hit.
Vegetation height
Q: Are succulents woody or herbaceous for the purposes of measuring vegetation height?
A: Woody.
Soil Stability
Q: During the soil stability test, if a soil floats initially and then sinks before 5 minutes is up but also stays solid, we would consider it a class 6. But is it considered hydrophobic also?
A: If the sample eventually sinks, it is not hydrophobic. Also, you wouldn’t call it a class 6 until you have dipped it five times and still have 75% or more of the sample on the sieve.
Q: What if soil sample area is directly in middle of a spiny shrub (e.g. shortspine horsebrush or cholla) or bunch grass?
A: Move to the edge of the base of the bunch grass or shrub and take your sample from the edge of the base.
Q: If we are surveying in a rocky area and our soil sampling points along the transect mostly fall on rock but there’s soil near the sample points, do we just sample that soil?
A: Try to sample the soil that is on the plot. If no soil is at your sample point, move a standard distance (e.g., 15 cm) down the transect and attempt a sample. Continue to move down the transect until a sample is obtained. If no soil is captured by the transect, move off the transect to the little pockets of soil wherever they may be within the plot boundary. If there is absolutely no soil on the plot, do not test soil stability. See rule 3.4 of the Soil stability method in the Monitoring Manual for more information.
Q: How do we sample soils when there’s continuous embedded litter?
A: Rule 3.4 in the soil stability section of the Monitoring Manual states that you treat embedded litter similar to rocks. So move down the transect a standard distance until you are able to collect a soil ped.
Q: Does a dead shrub count as canopy for the soil stability sampling form?
A: Yes.
Q: How do we sample properly in the rain or when the soil is wet?
A: Collect the samples as best you can without disturbing the surface structure. Allow the samples to dry in your vehicle or another protected area before running the soil stability test.
Species Inventory
Q: Are there particular genera in which it’s okay to only identify plants to the genus level?
A: To the extent possible, identify plants to species. Especially if the plant species composes >3% cover on the plot (i.e. you hit it more than five times during your line-point intercept recording). Also keep in mind that, if you have more than one plant species in that genus on the plot and you only identify to genus, then you’re not capturing the species diversity of the plot. That being said, there are some plants (e.g. Astragalus) where you need a seed pod and a flower and a significant chunk of time with a dissecting scope to identify to species. That just isn’t practical. We don’t have a set list of those genera because it depends on the local situation. Instead, we recommend you consult with the project coordinator and local botanists to identify the common, difficult to identify genera in your study area.
Q: Do we need to fill out the species inventory data sheet in DIMA if the plot species list already includes all the plants we find during the inventory?
A: Yes. The plot species list in DIMA is considered a draft working list and is not a final dataset. DIMA and other reporting databases will not run analyses on the plot species list. The species inventory data must be contained within the Species Richness form (see the Entering Field Data tutorial for tips on setting up the data form on the DIMA tutorials page).
Plant Density
Q: I read in the methods that we are supposed to count the number of individual plants for each target species, but for some reason I remember hearing during training that we are supposed to be estimating percent cover for each target species. Which is correct?
A: Count the number of plants. This is a density method and doesn’t capture cover. Other methods (e.g. Line-point intercept) do, however.
Sampling Plots
Q: Is it okay to visit all points within a stratum, and then visit all plots in another stratum? For example, could we do all the Alkaline sites first and then all the Piñon-Juniper sites next?
A: Yes. As long as you visit plots in order within a group or stratum, you can complete a stratum in any order. Keep in mind that if you do not anticipate sampling all of plots you should attempt an even distribution among strata each season.
Q: After rejecting a point, what is the next step in terms of choosing a backup? For example, while in the field today we rejected CL-12 because a new road has been constructed through the plot. Do we wait to get through all of the other accepted CL points before starting on the backups?
A: Yes. Continue through the primary points. Once you get through CL-13, CL-14, CL-15, for example, then you would visit CL-16 to replace CL-12.
Q: If a plot was previously established using a 50 m transect length but current protocols call for a 25 m transect, which length do we use when revisiting plots?
A: Use the plots’ original transect layout at repeat plots. This includes maintaining consistent transect lengths, transect azimuths, photographs, and methods. Maintaining consistency over time enables you to detect actual ecosystem changes—if any—rather than wondering if the differences over time are due to changed protocols.
Q: During a repeat visit to a plot, how do we know if we should dig a new soil pit?
A: You only need to do a new plot characterization if the data from the previous visit are incomplete or incorrect. This might include improving driving directions, filling in soil series and soil map unit information, the describing landform, etc. If you arrive at the plot and there are several red flags in the previously recorded information, you should do a new plot characterization or at least dig a soil pit to confirm those original data. To review previous plot characterization information in DIMA go to “Edit Plot” and click through the Plot Description tabs to see what was recorded.
Plot Characterization
Q: We noticed that the DIMA form and the paper data sheets for plot characterization are pretty different. For example, the paper data sheet asks for class ranking of rills and gullies while DIMA just asks whether wind and water erosion are occurring. Is it okay to not use the paper data sheets for the plot observation?
A: Yes, the DIMA form is rather different right now. You may also notice that it’s similar to the form for Interpreting Indicators of Rangeland Health (IIRH), however. The preference would be that if you are doing IIRH just use the DIMA observation form. If you aren’t, use the BLM’s AIM paper data form and then fill out as much of the DIMA form as you can. Any information captured by the paper form that DIMA doesn’t have a specific field for, put into DIMA’s notes fields.
Q: What is our objective in digging soil pits at each plot?
A: At the generic BLM field office scale, the AIM Strategy supports “improvement and stewardship of geospatial data layers, including land cover, soils, ecological sites, and riparian and aquatic resources” to address the question, “What is the location and abundance of priority renewable resources (both terrestrial and aquatic) within the field office?” (p. 13). At the regional scale, the strategy supports “complete soil and ecological site mapping” to address the question, “What is the extent and trend of vegetation communities relative to potential in the ecoregion?” (p. 15). Broadly speaking, the reasoning behind this is that soil properties like texture and color give BLM key contextual information for interpreting monitoring data and answering our management questions (see detailed discussion in this Duniway et al. paper, esp. pages 11-15).
For example, let’s say that half of the seedlings in a post-fire area meet plant cover and density objectives according to monitoring data and half do not. Without additional contextual information, it’s tough to interpret why that might have happened. However, when you look at how soil properties relate to the seedings, it may turn out that the seedings that succeeded were on soils with a loamy surface texture whereas the seedings that failed are on soils with a clayey surface texture. Thus soil properties could enable you to learn from your monitoring data and improve effectiveness of seedings in the future by focusing resources on loamy soils and/or altering seeding methods on clayey soils to improve success.
Here is a great reference video for identifying soil horizons. This video is a little more in depth than most AIM plot characterizations require, however the principles (first observe morphology-structure, color, coarse fragments, rooting characteristics, calcium carbonates–then identify horizons using texture etc.) apply to all soil pit characterizations.
Q: Should we be using decimal degrees or UTM when entering spatial data into DIMA?
A: Decimal degrees are preferred. Additionally, all shapefiles should be recorded in the NAD83 datum.
DIMA
Q: I need to import data from one database into another. How do I do that?A: Under the administrative functions, you can choose to do a data import under the data management options. Detailed instructions on how to import data can be found on the DIMA tutorial page.
Q: How do I export transect GPS waypoints to a shapefile?
A: The DIMA tutorial page has a walkthrough that explains how to export shapefiles from DIMA. Use the qrySitePlotLine table to gather your line GPS waypoints.
Q: When I select a site, I get a dialog box that says something about “Runtime Error 94”. What does this mean?
A: The reason you were having issues accessing the site is that one of the plots in that site didn’t have a PlotID field filled out. This is an artifact from DIMA v2.5; the random PlotID deletion bug has been fixed in later versions. So, when this error occurs:
- 1) Go to Support Tables–>Show Access “Database” Window2) Open the tblPlots table3) Use the filter function to identify “Blanks” in the PlotID field. 4) Enter the appropriate PlotID.
Q: I accidentally put a plot in the wrong site. How do I move it to the correct site?
A: In DIMA go to Administrative Functions–>Data Management–>Associate a Plot with a Different Site.
Q: We get an error dialog box about an “invalid name for a sheet or chart” when we run a species richness report. What does this mean?
A: One or more of your plots contains an illegal character: /, \, ?, *, [, or ]. If you change the offending plot name[s] to not use any illegal characters, the report function should work without throwing an error.
Do you have questions that weren’t answered here? Contact Aleta Nafus (anafus@blm.gov) to ask them and suggest additions to this FAQ.