The Purpose of the Following Protocol Is to Provide Information About Soil Movement And

USDA Forest Service Page 2 1/20/03

Erosion Pin Protocol, post-Biscuit Fire

Siskiyou IRS, LTEP

C. Edgar, Oct. 2002

Updated 1/20/2003

The purpose of the following protocol is to provide information about soil movement and erosion in the aftermath of the Biscuit fire and the prescribed fires associated with it. The measurements utilize the existing grid of rebar installed to guide sampling of the LTEP plots. The rebar, driven vertically into the ground, provide ready-made erosion pins with which to assess fire-related soil movement on the burned Siskiyou LTEP sites. The rebar are on 25 m grid spacing following one of three spatial configurations (see other LTEP protocols for details).

In each mensuration plot burned during the Biscuit fire or during the following prescribed burns, locate all gridpoints using plot maps. The affected mensuration plots are as follows: block I (all), block B (T-N and C), block III (E-1, E-3 and C). Accuracy is essential, as the grid is being partially reconstructed because many of the identifying tags were melted.

First, assess the damage to the aluminum ID tag. Tags with melted portions are “melted”, tags with some heat damage, blackening, etc are “lightly damaged” and undamaged tags are “intact”. Remove all tags or tag remnants and place in a labeled plastic bag for later analysis. If no tag or remnants can be found, note on datasheet. In all cases, replace the tag, ensuring accurate numbering. Flag each completed gridpoint with a pinflag.

Then, measure the distance from the wire which held, or is holding, the tag to the uphill side of the groundline. Record to the nearest 0.1 cm as “wire to ground”.

Measure and record the predominant slope (%) around the gridpoint using a 2m length of PVC pipe and a clinometer. By resting the PVC pipe, the clinometer and your head on the ground, you can see into the clinometer and obtain a very accurate measure of slope. Be sure to estimate the slope directly downhill from the rebar, at the aspect predominant in a 5 m radius around the gridpoint. Adjust for abnormalities by estimation or moving the slope measurement slightly off to the side. Record in comments any feature that would alter potential erosion around the rebar (e.g. trees, logs, stumps, holes, etc).

Measure and record the predominant aspect (degrees) around the gridpoint using a compass. Estimate aspect from about a 2m span around the gridpoint, similarly to the slope measurment.

Last, slip a metal washer over the rebar and guide it to rest on the ground. This will require removal of the wire holding the ID tag in place. Move aside any large objects (logs, big rocks, etc) that would prevent the washer from resting on the soil. Make certain that the rebar is firmly driven into the ground and cannot be easily moved about. Reinstall within 30cm of original location if necessary (make a note of this!). Measure and record the distance from the top of the rebar to the washer/groundline on the uphill side to the nearest 0.1 cm as “rebar to ground”. Do not replace plastic caps on rebar, as this tends to drive rebar further into ground and/or loosen it.

Take a photograph of each gridpoint from approx. 2m downslope. Center the rebar in the frame and place a dry erase board off to the side with the following information: date, plot/site, gridpoint x,y.

Erosion pin re-measurements

To make subsequent measurements of erosion pins, simply measure from the new soil line to the top of the rebar (on the uphill side). Place the end of the tape on the washer, or directly on the soil if it has been covered, and measure to the nearest 0.1cm to rebar top. If a large rock, log, etc. has rolled against the rebar, make note and attempt to measure down to the soil line. If not possible, then measure from the top of the object. If the washer has become stuck above the present soil line, push it down against the soil and then measure. If the rebar is missing, attempt to find it and determine the cause. Reinstall according to intial instructions. If the rebar has become buried, use a metal detector to locate, then measure down from soil line to rebar top.

Try and complete each remeasurment during a drier period between significant precipitation events. Additional photos should be taken annually.