Managing the Effects of Forest Harvesting on Soil Quality in B.C.

1. Managing the Effects of Forest Harvesting on Soil Quality in B.C. • M.Curran, Ph.D,P.Ag. • BCFS, Research

2. Outline • Tutorial case description • “Sustainability” as context for guidelines • Soil information for planning • Soil disturbance processes (hazards) • Soil disturbance standards • Practical Application • Questions/Discussion • Tutorial Assignment

3. Case specific learning outcome: • Understand the common characteristics of forest soils • with an emphasis on soil physical attributes and management tools to prevent compaction.

4. Accomplish the following tasks: • Interpret the results of a harvesting experiment and apply this knowledge to a new harvest site. • Describe your learning in written format (as individual students) and orally (as a working team). • Post on the course web site responses to the guiding questions.

5. References for tutorial: • Biophysical Resources of the East Kootenay Area: Soils by L.E. Lacelle. 1990. • Hazard Assessment Key Guidebook • Soil Conservation Guidebook • Soil Conservation Surveys Guidebook

6. Outline • Tutorial case description • “Sustainability” as context for guidelines • Soil information for planning • Soil disturbance processes (hazards) • Soil disturbance standards • Practical Application • Questions/Discussion • Tutorial Assignment

7. “Sustainable Forest Soils” • “Ensuring that the biological, chemical and physical integrity of the soil remains for future generations of ___(people, trees, etc.) • Addressed at many levels, through operations, standards, and now protocols • Often tracked in terms of Criteria and Indicators… • BUT the adaptive management process is likely just as important as the indicators

8. Adaptive Mgt. Process Strategic Direction Data/results Guidelines R & D Monitoring (C&E) Training OPERATIONS Best Mgt.Practices

9. “Sustainability Protocols” • Set Criteria and specific Indicators of sustainable forestry • Encourage countries to report on the status of these Indicators • However, protocols like the Montreal Process have a number of “b-type” indicators that require field validation (eg, compaction) • Therefore, compliance with standards is often used as a proxy (eg, CCFM C&I)

10. Soil Disturbance (a Proxy) • Any physical, biological, or chemical disturbance to the soil caused by ground-based equipment (operations) • May be inconsequential, beneficial, or detrimental depending on the net effect on growth limiting factors and hydrologic properties

11. MP talks about area with “significant compaction” Bad air? BUT, what does compaction mean on a given forest site?

12. Soil Disturbance as a proxyfor productivity/hydrologic effects • In many NA ecosystems, we need at least 10 to 20 years data to draw conclusions about the effects of various practices • Therefore, we use soil disturbance as a proxy that we can observe and regulate at the time of harvesting, site preparation, etc. • However, when we discuss or read about “Soil Disturbance” there are inconsistent approaches and methods a common approach is needed.

13. @ 15 YRS @ 10 YRS @ 3 YRS Mean Douglas-fir volume - Gates Creek (Smith & Wass, 1991; Wass & Senyk, 1999) 150 125 100 R / R % of volume on undisturbed soil S / NR 75 T / NS T / R 50 T / NR 25 0

14. Outline • Tutorial case description • “Sustainability” as context for guidelines • Soil information for planning • Soil disturbance processes (hazards) • Soil disturbance standards • Practical Application • Questions/Discussion • Tutorial Assignment

15. Soils information for planning • Soil maps provide general information on the soils and landforms present • Site-specific data collection verifies and (OR) provides information used in determining soil disturbance limits • Harvest planning should use both of these whenever maps are available.

16. “Soil Landscapes” • Soil = f (t) { pmtl + topog + veg + climate } • Soil will vary with above • Soil will be similar with above… • Therefore, repeating units across landscape • We can map these units and interpret them • Maps = framework for communication of experience with soil

17. Primary criteria for mapping • Origin of parent material • Lithology (mineralogy) of coarse fragments • Texture (coarse frag’s; fine fraction) • Above of interest to Forest Engineering

18. Some secondary criteria • Soil development • degree of weathering • depth of horizons • Diagnostic horizons (eg, clay rich) • Organic matter content

19. SIL / Planning level 4 reccie / Regional 3 “baseline” 2 detailed / Local 1 site-specific Field checks / scale 25 %, 1:100,000 50 %, 1:50,000 90 %, 1:20,000 100 %, 1:5,000 Survey Intensity Level (SIL)

20. Typical soil individuals (map) • Soil Associations (typical maps) • “similar parent material and development” • Soil Series (detailed, agricultural maps) • “same parent material, development, texture”

21. Map Reliability • Reliability = how well it reflects a given point on the ground • Function of scale, access, surveyor skill • Will vary with the property of concern • eg, texture versus actual development • general purpose or specific mapping?

22. Outline • Tutorial case description • “Sustainability” as context for guidelines • Soil information for planning • Soil disturbance processes (hazards) • Soil disturbance standards • Practical Application • Questions/Discussion • Tutorial Assignment

23. Soil Disturbance – is it all Degradation?

24. Tree growth limiting factors • Any factors that limit growth • Concept of most limiting factor • May be direct or indirect factors

25. Direct growth limiting factors

26. Direct growth limiting factors • Water • Nutrients • Light • Aeration (CO2, O2) • Temperature (soil, air)

27. Indirect growth limiting factors • Affects direct factors, eg:

28. Indirect growth limiting factors • Affects direct factors, eg: • Competing vegetation • light • water • Rooting substrate (volume) • Root rot

29. Net effect on tree growth • Resulting tree growth is sum of positive and negative effects • Common negative effects: • reduced aeration from compaction • loss of nutrients and organic matter • Common positive effects: • reduced competition • warmer soils

30. Soil disturbance processes • what is soil disturbance • what is soil degradation • what processes lead to degradation • (strategies to manage disturbance)

31. Soil Disturbance • Any physical, biological, or chemical disturbance to the soil • May be beneficial or detrimental, depending on net effect on growth limiting factors

32. Beneficial Disturbance • Foresters often create disturbance on purpose as site preparation to ameliorate seedling growth-limiting factors • Net effect would have to be positive • Growth is limited by most limiting factor • Identify and manage for these • Don’t compromise long-term productivity

33. Soil degradation • Any disturbance that negatively affects soil productivity • In B.C. Forestry, trees are the “bioassay” • FPC/FRPA targets potentially detrimental disturbance • some of concern for drainage as well (FRPA)

34. Processes leading to degradation: • Compaction • Displacement (min. soil; forest floor) • Erosion • Mass Wasting (cut/fill failures) • (Part of management framework)

35. Erosion • Surface soil eroded primarily by water (splash, sheet, rill erosion) • Loss of fertile topsoil layers • Loss of effective rooting volume • Exposure of unfavourable subsoils • Drainage diversion • Sedimentation of watercourses

36. Erosion • Controlling factors: texture, coarse fragments, slope, climate • Manageable factors: machine traffic, degree of scalping, drainage control

37. Mass Wasting • “Minor” cut and fill failures • Often result in drainage diversion • Can lead to larger landslides • Loss of productive growing site • Impacts on downslope values • Safety concerns • Also use slope stability indicators (LMH47)

39. Mass Wasting • Controlling factors: parent material, climate, slope, topography • Manageable factors: amount and extent of excavation, drainage control, machine traffic, seasonal soil conditions (wetness, snow, frost)

40. Compaction • Compaction and Puddling result in the alteration / loss of soil structure (architecture of pores) • Bulk Density increase (penetrability) • Infiltration decreases (more runoff) • Aeration decreases (less biological activity)

41. Compaction • Controlling factors: texture, coarse fragments, forest floor depth/type, (soil depth, mineralogy) • Manageable factors: machine traffic, machine type/dynamic loading, seasonal soil conditions (wetness, snow, frost)

44. Table 3. Bulk density (kg m-3) of 0-10 cm soil depth in 1981 and 1997 among three treatments and two disturbances at Gates Creek. Treatment Disturbance Year Prob>T 1981 1997 Non-stumpedUndisturbed 1231 1246 0.88 Track 1613 1405 0.001 Raked Rake 1469 1373 0.23 Track 1671 1469 0.03 Scalped Scalp 1119 1210 0.20 Track 1724 1420 0.000

46. Aeration Porosity (Nakusp)

49. Dispersed traffic = concern • Aeration porosity definitely affected • Literature suggests is could affect trees • Therefore, need to monitor and check • Institute BMP for now • Adjust guidelines as hard data available • Hard data needs a framework (plasticity)

50. Soil Plasticity (Approx., CSSC) Very Plastic Plastic Slightly Plastic Non-Plastic