Iron Canyon Soil Monitoring Site I - Post Harvest Site II - Pre Harvest Site II - Post Harvest Cumulative Effects Now we will get into post-harvest effects, and different ways of analyzing the data

Iron Canyon II Feller-Buncher Harvesting August 2003, 23% Soil H20 at 0-60 cm Whole tree yarding - reduces fuels in the unit, creates larger landings. Harvested in August at the driest time of year, so impacts should be as minimal as possible, best case scenario.

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Pre-Harvest Undist 675 Dist 216 Skid 109 Review pre-harvest “legacy” disturbance Units- Feet (1,000 ft total in transects)

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Disturbance Class Matrix Post-Harvest Undist Dist Skid Pre-Harvest 675 216 109 We can now build a disturbance class matrix, essential to understanding cumulative effects. Each foot of transect goes into a new post-harvest category, INDEPENDENT of what it was pre-harvest Units- Feet (1,000 ft total in transects)

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Disturbance Class Matrix Post-Harvest Undist Dist Skid Pre-Harvest 675 157 216 109 Only ¼ of the 675 feet remained undisturbed Units- Feet (1,000 ft total in transects)

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Disturbance Class Matrix Post-Harvest Undist Dist Skid Pre-Harvest 675 157 411 107 216 109 The remainder was subsequently disturbed Units- Feet (1,000 ft total in transects)

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Disturbance Class Matrix Post-Harvest Undist Dist Skid Pre-Harvest 675 157 411 107 216 46 147 23 109 Only 1/5th of this was not subsequently impacted in the second entry Units- Feet (1,000 ft total in transects)

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Disturbance Class Matrix Post-Harvest Undist Dist Skid Pre-Harvest 675 157 411 107 216 46 147 23 109 12 49 48 We have more additional area in skid trails than we had in total after the previous entry Units- Feet (1,000 ft total in transects)

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Disturbance Class Matrix 2003-Harvest Undist Dist Skid 1960’s-Harvest 215 607 178 Cumulative 675 157 411 107 216 46 147 23 604 109 12 49 48 239 Only now can we address cumulative impacts, lumping old and new disturbance in the same categories. Whether or not this is appropriate? We will see in a few minutes. Units- Feet (1,000 ft total in transects)

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Disturbance Class Matrix PRE Harvest POST % Change Undist 67% 16% -77 Dist 22% 60% +180 Skid 11% 24% +119 NET EFFECT Percent Change in Pre-Harvest Classes

Iron Canyon II Soil Monitoring Post-Harvest Disturbance Extent POST PRE This is a result of FAILURE TO UTILIZE LEGACY & DESIG SKID TRAILS. However, depending on the SEVERITY of the disturbance, this may or may not be significant.

Iron Canyon II Soil Monitoring Post-Harvest Disturbance Strength profiles in March, very moist time of year so numbers don’t get any lower than now. Note the landing for relative impact.

Iron Canyon II Soil Monitoring Post-Harvest Disturbance Strength measurements as affected by moisture, pre and post harvest. Note the relationships stay the same between classes, despite large absolute changes as soils wet and dry through the growing season.

Iron Canyon II Soil Monitoring Soil Strength Before & After Harvest 10 Month Averages at 10-20 cm This is ONE way to look at the data- looking at only PRE harvest categories and seeing how they change.

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Disturbance Class Matrix Post-Harvest Undist Dist Skid Pre-Harvest 675 157 411 107 216 109 Remember most of the UNDIST class was subsequently disturbed. Units- Feet (1,000 ft total in transects)

Iron Canyon II Soil Monitoring Soil Strength Before & After Harvest 10 Month Averages at 10-20 cm Since most of the UNDIST was subsequently disturbed, we have increases in strength; same in all classes. This is a very objective way to analyze the data.

Iron Canyon II Soil Monitoring Bulk Density Before & After Harvest Averages at 10-20 cm We see the exact same patterns with bulk density. Additional disturbance in each class.

Iron Canyon II Soil Monitoring Bulk Density Before & After Harvest Averages at 10-20 cm 24% of Harvest Area Putting in our bulk density threshold, we’ve added enough new disturbance to put the skid trails over, which represent ¼ of the unit. We could stop right there and give the area a failing report card, but there’s more to it. Each one of these POST bars is now a mix of categories, so that may not be the most appropriate way to analyze & report the data.

Iron Canyon II Soil Monitoring Pre- vs. Post-Harvest Disturbance Disturbance Class Matrix Post-Harvest Undist Dist Skid Pre-Harvest 215 607 178 Cumulative 675 157 411 107 216 46 147 23 604 109 12 49 48 239 Remember the matrix- we can look for interactions between pre & post categories to see more specifically where the serious impacts are found. If we plot each of these 9 categories separately…. Units- Feet (1000 ft total in transects)

Iron Canyon II Soil Monitoring Post-Harvest Disturbance Bulk Density, Post-Harvest (10-20cm) 0.00 0.20 0.40 0.60 0.80 1.00 1.20 undist dist skid UNDISTURBED DISTURBED SKID BULK DENSITY (g/cm3) POST PRE We get a complicated graph, but well worth taking the time to digest. All of the darker bars are skid trails, old or new. NOW we can start to answer questions about cumulative impacts: Are new skid trails worse than old? Does skidding on old trails make them worse? These and other questions can now be answered.

Iron Canyon II Soil Monitoring Post-Harvest Disturbance Adding our threshold, we see the only categories over threshold are where we skidded on previously disturbed ground, representing 7% of the unit. That could lead to some perverse conclusions, such as never reuse skid trails, but if we at least concentrate impacts we can mitigate them.

Disturbance Category: Region 5 Standard: 10% Porosity Reduction Iron Canyon I Soil Monitoring Looking Back…. 2001 UNIT - HARVESTED IN MAY Averages by Disturbance Category (10-20 cm depth) Disturbance Category: Low Mod High units bulk density 0.89 0.94 1.01 g/cm3 Now that we have a reliable estimate of undisturbed bulk density, we can look back at the first unit, harvested in may. Skid trails are over threshold, moderate class is at threshold. We would now conclude that half to 2/3 of the unit has detrimental disturbance. This is a consequence of soil moisture alone; harvest timing can be critically important, especially on sensitive soils. Region 5 Standard: 10% Porosity Reduction Initial Db: 0.76 Threshold Db: 0.95

Disturbance Basics EXTENT % area, depth SEVERITY undisturbed extreme DISTRIBUTION dispersed concentrated DURATION short term long term mitigation? natural recovery? We’ve spent our time talking about the former two; what about the latter two?? These things are NOT easy to measure, but they are important considerations, especially when looking at mitigation or cumulative impacts.

I used GPS to map the pre-harvest skid trails and landings I used GPS to map the pre-harvest skid trails and landings. Incidentally, the transects estimated 10.9% of the unit in skid trails, GPS showed the real number was 10.7%.

I’ve added the post-harvest landings and service roads; post-harvest skid trails were much too extensive to map feasibly.

These are the areas where we have room for improvement when soil impacts and cumulative effects are a concern. It absolutely would have been “practicable” to reuse the old truck road and many skid trails. In many cases the new trails parallel the old ones 10-30 ft away.

PRE POST UNDIST DIST SKID These are the 5 permanent measurement transects laid side by side, the top half pre harvest category and the bottom half post harvest category. We see patterns of wider skid trails, and new skid trails right next to old ones. Transect 4 has no undisturbed ground post harvest.

Conclusions from Iron Canyon II Soil Monitoring Results Meaningful disturbance classes can be established easily and objectively The ocular disturbance classes were quite pragmatic on the ground; they were validated well by quantitative measures.

Conclusions from Iron Canyon II Soil Monitoring Results Meaningful disturbance classes can be established easily and objectively Pre-harvest stands came with legacy impacts that remained significant after decades

Conclusions from Iron Canyon II Soil Monitoring Results Meaningful disturbance classes can be established easily and objectively Pre-harvest stands came with legacy impacts that remained significant after decades Legacy impacts were compounded by recent thinning, creating cumulative impacts

Conclusions from Iron Canyon II Soil Monitoring Results Meaningful disturbance classes can be established easily and objectively Pre-harvest stands came with legacy impacts that remained significant after decades Legacy impacts were compounded by recent thinning, creating cumulative impacts Assessing cumulative impacts requires pre-harvest monitoring If you only take a post-harvest look, legacy impacts go largely unnoticed. What we measure for baseline may be compromised, and cumulative impacts will be consistently underestimated.

Conclusions from Iron Canyon II Soil Monitoring Results Cumulative impacts exceed thresholds on some skid trails About 1/3 of the skid trails were over threshold, comprising 7% of the unit as a whole.

Conclusions from Iron Canyon II Soil Monitoring Results Cumulative impacts exceed thresholds on some skid trails Old and new skid trails were coincidental at best. There was little to no effort to reuse old skid trails, and designated skid trails were largely ignored. This is an issue with sale layout and contract administration, which is fairly easy to improve upon.

Conclusions from Iron Canyon II Soil Monitoring Results Cumulative impacts exceed thresholds on some skid trails Old and new skid trails were coincidental at best Mechanical operations on these soils will produce detrimental impacts We still have not addressed the duration aspect, or “natural recovery” on skid trails. I plan to monitor the transects in that unit every few years to look at that, and also look at infiltration changes after the soils have settled a couple years.

Conclusions from Iron Canyon II Soil Monitoring Results Cumulative impacts exceed thresholds on some skid trails Old and new skid trails were coincidental at best Mechanical operations on these soils will produce detrimental impacts The result is more areal impacts, adding to legacy disturbance for next harvest.

National Forest Soil Scientists are Charged with Monitoring Many Forest personnel are discouraged by today’s requirements of planning and implementing projects. If, through systematic monitoring, less defense of “professional judgment” and “credibility” are necessary, more funds are available for project planning & implementation. Monitoring need not be difficult or expensive. It’s less expensive than planning & lawsuits!

THANKS TO: Dr. Robert Powers - PSW Brad Rust – Shasta-Trinity NF Scott Miles – R-5