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Forest harvesting impacts on streams Forum Northland, Whangarei, 7 April 2011

Forest harvesting impacts on streams Forum Northland, Whangarei, 7 April 2011. John Quinn NIWA, Hamilton. Brian Smith, Greg Steward, Josh Smith, Kerry Costley, Aslan Wright-Stow – field and lab assistance

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Forest harvesting impacts on streams Forum Northland, Whangarei, 7 April 2011

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  1. Forest harvesting impacts on streamsForum Northland, Whangarei, 7 April 2011 John Quinn NIWA, Hamilton

  2. Brian Smith, Greg Steward, Josh Smith, Kerry Costley, Aslan Wright-Stow – field and lab assistance Mark Meleason, Kevin Collier, Dave Rowe, David Reid, Ian Boothroyd, Aslan Wright-Stow, Chris Phillips, Lisa Langer, Greg Steward Ernslaw One, Rayonier and CHH Forests – staff and funding support NZ Foundation for Research Science and Technology Acknowledgements

  3. Stream habitat 101 Pasture afforestation effects Impacts of logging What are they? Magnitude and duration? Riparian buffer mitigation benefits & limitations Monitoring tools Outline

  4. Shade Leaf litter food Terrestrial insect foods Wood input Cover for fish Water quality Streambed sediments Cool, moist riparian area Reflects catchment & riparian condition NZ stream habitat components

  5. NZ headwater streams were naturally shaded More open further downstream Pasture homogenises - all unshaded Clearfell logging = temporary disturbance Flow, habitat, water quality & sediment Food types & temperature Magnitude & duration of harvesting influenced by Stream size Forestry practices Catchment characteristics Riparian buffers Weather/luck! Land clearance & clearfell logging

  6. Improved water quality No livestock (but feral animals increase) Fewer disease causing bugs Less streambank riparian damage Less fertiliser & nutrient loss– less algae, clearer lakes Fewer agrichemicals Slopes stabilised – less sedimentation, clearer water Streams shaded – cooler for sensitive species, cover for fish Reduced flows Pasture afforestation effects

  7. Whatawhata# Waitangi Day storm 2007 (110 mm in 8 h, 90 mm in 4 h) 29 slip in 200 ha pasture 2 slips in 180 ha 6 yr pines Manawatu Feb 2004 storm* Forest cover (native or exotic) reduced landslide susceptibility by 90% Via effects on soil moisture, pore water pressure root reinforcement Climate change will heighten these benefits Afforestation benefits – erosion/sediment #Quinn, J.; Basher, L. (2007): Testing times at Whatawhata. Water and Atmosphere 15 (2): 5. *Dymond, J.R.; Ausseil, A.G.; Shepherd, J.D.; Buettner, L. (2006). Geomorphology 74: 70-79.

  8. Mid-late rotation pine forests Native • Resemble native forests • Hydrology • water yield < pasture1 • more ephemeral length • lower flood flows • Nutrient dynamics • May be more retentive2 • Shade3 • Temperature • Periphyton biomass/prodn • Litter input mass4& wood5 • Expect +/- similar faunas Pine 1= Fahey et al 2004, Quinn et al 2009 2= Quinn & Ritter 2003 3 = Davies-Colley & Quinn 1998; 4 = Scarsbrook et al. 2001; 5 = Baillie & Davies 2002

  9. Index of biotic integrity(IBI) - relative to native reference Impairment 100 Nonimpaired 90 80 70 Slight 60 % of reference IBI 50 40 Moderate 30 20 Severe 10 0 Native Pasture Pine Afforestation & streamlife from data in Quinn et al. 1997 NZ J Mar Fw Res 31:579-598.

  10. Main impacts on stream habitat: 1. Sediment erosion & nutrient yield Local and downstream (rivers, lakes, estuaries) 2. Stream habitat What about harvesting?

  11. Clearcut habitat pressures • Flows, sediment & nutrient flux increase • Organic matter • Initially v. high if slash deposited • Low DO possible for c. 0.5-1 y or until scoured • Initial increase on DOC & POC downstream • Later low until riparian veg regrows • Lighting and temperature • High when slash “cleaned” or input avoided • High periphyton & temperature • Stays low under slash • Complex disturbance • Timing and magnitude of impact & recovery vary • Amongst stream attributes • Between streams of different size • Management practices

  12. Oxygen Invert. IBI Clarity Flow Temp Periphyton biomass Generalised clearcut effects on small (2-6 m) Coromandel streams 40 0 20 30 10 Time (years) Adapted from: Fahey, B.; Duncan, M.; Quinn, J. (2004). Impacts of forestry. In: Freshwaters of New Zealand, pp. 33.31-33.16, New Zealand Hydrological Society and New Zealand Limnological Society, Christchurch.

  13. Stream/catchment size Harvesting less intense/longer duration in large catchments Effects dampened c.f. small streams – lower magnitude but longer duration Shade takes longer to restore in wider streams But change in lighting less in wide streams (>15m) Management esp. riparian buffers Weather (luck) Impact modifiers

  14. Logging & streamflow Glenbervie Forest: Post-logging flow increased: 30-40% in normal years; 70% in a wet year (Rowe 2003) Puruki CNI (34 ha)# 1.4 1.2 1 0.8 Pine/pasture flow ratio 0.6 0.4 0.2 0 y-7 y-6 y-5 y-4 y-3 y-2 y-1 y+1 y+2 y+3 y+4 y+5 y+6 y+7 Years from logging #Quinn, J.M.; Ritter, E. 2003: Proceedings Rotorua Lakes 2003:Practical Management for Good Lake Water Quality, Rotorua, p.149-157.

  15. Causes More flow - streambank erosion Earthworks runoff Soil disturbance & slips at logging Road and clearcut runoff Potential impacts Murky water Stream, lake, estuary accelerated sedimentation Altered vegetation (e.g., mangrove spread, seagrass loss) change in invertebrates (e.g., shellfish to worms in estuaries) Harvesting erosion risks?

  16. Post-harvest sediment yields 10’s to low 100’s t/km2/y Slide: Chris Phillips Landcare Research

  17. Pakuratahi (HB erodable hills)# Pre-harvest: pine (30 t/km2/y) 45% of pasture At harvest: pine (89 t/km2/y) 217% of pasture Mostly from road side-cast, landslides and channel scour Post-harv (1-2 y): Pine (150 t/km2/y) 147% of pasture 3 y post-harvest: Pine (17 t/km2/y) 27% of pasture Infer Pine SS < pasture over rotation Sediment yield c.f. pasture #Fahey, B.D.; Marden, M. (2000). Journal of Hydrology (NZ) 39: 49-63. Fahey, B.D.; Marden, M.; Phillips, C.J. (2003). Journal of Hydrology (NZ) 42(1): 27-38.

  18. Instream ecological effects of sediment • SS effects • Conc.&Time • Native fish www.niwascience.co.nz/ncwr/tools/turbidity • Salmonids • Newcombe, C.P. (2003). J. Am Wat Res Assoc 39: 529-544. • Avoiding conspicuous effects on clarity should protect biota from suspended sed

  19. Sediment loads Ideally need storm monitoring of flow and SS or turbidity Turbidity sensors or auto-samplers for SS sampling Water level recorder Relatively expensive Visual clarity (is change conspicuous? RMA sections 70 & 107) Routine (e.g., fortnightly) black disk measurement Relate to state of flow at a gauged stream Streambed sedimentation Guidelines being developed - Envirolink Pebble count method Size class of 100 stones Visual assessment of bed size class percentages Suspendable fines – Quorer Fauna biomonitoring of sediment and other impacts Stream or estuarine Sediment monitoring tools

  20. Pebble count results Buffered Clearcut Clearcut 100% 90% 80% 70% 60% Bed Composition 50% 40% 30% 20% 10% 0% s94 s95 s96 s97 s98 s99 s00 s01 s02 s03 s04 s05 s95 s96 s97 s98 s99 s00 s01 s02 s03 s04 s05 s95 s96 s97 s98 s99 s00 s01 s02 s03 s04 s05 w93 w94 w95 w96 w97 w98 w99 w00 w01 w02 w03 w04 w94 w95 w96 w97 w98 w99 w00 w01 w02 w03 w04 w94 w95 w96 w97 w98 w99 w00 w01 w02 w03 w04 Season/year Silt/Sand (<2mm) Small gravel (2-8mm) Small-Med Gravel (8-16mm) Med-Large Gravel (16-32mm) Large Gravel (32-64mm) Small Cobble (64-128mm) Bedrock Large Cobble (128-256mm) Boulders (>256mm)

  21. Case example Culvert blocked by slump Downstream scour and batter slumping Sediment input Sediment input example

  22. Sediment measures • percent fines from 6% to 27% (pebble count) • SIS levels 18-fold over background (Quorer) 16000 14000 12000 10000 8000 SIS (g/m2) + SE 6000 4000 2000 0 Upstream Downstream

  23. Downstream Impacts on invertebrates 100 60 80 50 60 40 % Sensitive (EPT) 40 30 Index of biotic integrity (%ref) 20 20 10 0 0 Ref. Ref. Upstream Upstream Downstream Downstream Upstream Ref.

  24. Short-term in steep, frequently flushed streams of NE NZ Expect long-term where slope lower & flows stable Key driver of invertebrate impact in small HB streams (Pakuratahi study¥) Key driver of estuarine impacts Sediment impacts ¥ Death, R. and Death, F. 2006. Forestry effects on stream invertebrate communities. Pakuratahi - Tamingimingi land Use Study. Hawkes Bay Regional Council.

  25. Monitoring clarity • Black disk vis • MFE guideline = change >33-50% is “conspicuous” • Regional plans and consents have various limits on clarity &/or related turbidity and suspended solids (SS) • Use in small streams limited by pool length for sighting • SHMAK clarity tube • dirtier water (vis <1 m) • Simple tool for runoff monitoring • Turbidity • Indirect measure of clarity and SS • OK for all stream sizes 10 10 1 1 Black disk visibility (m) 0.1 0.1 slope = -0.760 slope = -0.686 r = -0.923 r = -0.904 0.01 0.01 0.1 1 10 100 1000 0.1 1 10 100 1000 Turbidity (NTU) Suspended Solids (g/m3)

  26. Tairua clarity – boxplots/yr 5 80 5 80 Site 8, 94% harvested 70 Site 9, 25% harvested 70 4 4 60 60 50 50 3 3 40 40 2 2 30 30 20 20 1 1 10 10 0 0 0 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Clearcut Buffered Outlier Range (Upper) 75 % ile Median Black disk visibility (m) 25 % ile % harvested Range (Lower) Years 1993-2009

  27. 5 80 6 80 Site 9, buffered 29% harv Site 8, 94% harvested 70 70 5 P = 0.08, r2= 0.6 % P = 0.50 r2= -0.1 % 4 60 60 4 50 50 Black disk visibility (m) 3 40 % harvested 3 40 2 30 30 2 20 20 1 1 10 10 0 0 0 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Tairua clarity- trend analysis Years 1993-2009 Decline during harvest then recovery No harvest impact Clearer in winter

  28. Longterm – decadal and longer Bed core analysis using various markers Pine pollen, radio-isotopes Aerial surveys of intertidal vegetation Short-term Bed level surveys Sediment texture monitoring Changes in invertebrate fauna Source tracing of deposits using chemical/isotopes Hydrophobic fatty acids & resin acids Surface and subsoils in different land uses c.f. estuarine deposits Mixing models apportion sources Estuary sedimentation monitoring

  29. Engineering – codes of practice Ridgetop roading Store excavated sediment safely Filter road runoff Adequate “cutoffs” Prevent rill/channel formation Coarse sediment traps Road prep & maintenance Earthworks in dry period Oversow after harvesting Limit machinery near streams Riparian buffers Riparian trees stabilise banks Reduce near stream disturbance Filter sediment in sheet flow Managing forest sediment

  30. Reduce near-stream disturbance Stabilise streambanks  Slow/dam runoff promoting settling & infiltration Declines as slope increases Often bypassed by preferred flow paths (channels) Riparian buffers – do they reduce sediment in steplands? Slide: Chris Phillips Landcare Research

  31. 60+ m from road Gentle Slope < 150 Buffer > 20 m wide Culvert Slide: Chris Phillips Landcare Research

  32. N & P are essential for life Modest amounts support productive ecosystems In excess (too much of a good thing) Weedy streams Algal blooms/eutrophication in lakes Lake bottom deoxygenation Low water clarity Toxic blue-green algae blooms Nutrient effects

  33. 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 P yield at Purukohukohu 9-12 y after pines planted (Cooper & Thomsen 1988) 0-5 years after logging/replanting 1.8 1.6 1.4 c 1.2 kg P ha-1 y--1 1.0 0.8 0.6 0.4 b a 0.2 0 Pine Pasture Native Pine Pasture Native

  34. 14 14 12 12 10 10 TN export (kg /ha/ y) 8 8 6 6 4 4 2 2 0 0 Pine Pasture Native Pine Pasture Native N yield at Purukohukohu 9-12 y after pines planted (Cooper & Thomsen 1988) 0-5 years after logging/replanting

  35. Pine afforestation and logging effects 2000 1500 NO3-N (mg m-3) 1000 500 0 9911 9201 9711 9811 0011 7305 7405 7505 7605 7705 7805 7905 8005 8104 8205 8305 8405 8505 9611 0405 pasture pines planted Logged, replanted Puru longterm NO3 Quinn, J.M.; Ritter, E. 2003: "Effects of land use and pine forest logging on stream nutrients at Purukohukohu, Central North Island." In: Miller, N.C.; Miller, E.M. (eds). Rotorua Lakes 2003:Practical Management for Good Lake Water Quality, Rotorua, p.149-157.

  36. Forests export much less nutrient than pasture Logging may result in pulse losses May contribute to blooms - especially in enclosed bays Forest regrowth quickly reduces losses to low levels Sediment control measures also help control nutrient loss Conclusions on nutrients

  37. Logging impacts and buffers - Coromandel • Whangapoua 1999 • Unlogged • 4 native (N) • 4 pine/pine rip (P) • 4 pine/native rip (PR) • Logged 0-4 yr (av.66%) • 4 continuous buffer (HC) • 4 patch buffers (HP) • 8 clearcut (H) • Recovery followed • + Streams monitored at Whangapoua and Tairua Forests since 1992-3

  38. Measures • Rip. vegetation • Stream habitat • Lighting, bank erosion, stability, DO, Temp, sediment, wood, organic matter • Algae • Benthic inverts • 5 x 0.1m2 Surbers runs • Fish • electro-shocking

  39. Riparian vegetation - 1999 study Post-logging (HR)Buffer width = 18 m (6-30 m)

  40. Buffers moderate light impact Logging & stream lighting 70 p < 0.0001 60 50 40 Stream shade (% open) 30 20 10 0 H HP HC P PR N Boothroyd et al. 2004 FEM paper

  41. 30 26 22 18 14 22 Harvested no buffer (H) 10 18 21/01/99 11/01/99 31/12/98 14 Impact threshold sensitive invertebrates 10 Coromandel Stream Temperature (°C) Harvested with buffer (HC) 21/01/99 31/12/98 11/01/99 22 18 14 Mature pine with buffer (PR) 10 21/01/99 11/01/99 31/12/98 Buffers moderate logging effects on temperature

  42. Slash keeps temp cool 24 Cp 21 “stream cleaned” 22 20 Pine mature 18 Daily Max Temp (˚C) Cp 21 Slash 16 14 12 10 1/01/1996 8/01/1996 18/12/1995 25/12/1995 15/01/1996 22/01/1996 Date

  43. ON=ref Cp 22 Cp22-ON ON=ref OW 9-Dec-91 8-Dec-92 8-Dec-93 8-Dec-94 8-Dec-95 7-Dec-96 7-Dec-97 7-Dec-98 7-Dec-99 6-Dec-01 6-Dec-02 6-Dec-03 5-Dec-04 5-Dec-05 5-Dec-06 5-Dec-07 Stream size alters rate of temp recovery after logging 50ha 100% logged, 6 yr effect 30.0 25.0 20.0 15.0 Temperature (˚C) 10.0 5.0 0.0 6-Dec-00 -5.0 350 ha, 78% logged, >12 yr effect 30.0 25.0 20.0 15.0 Temperature (˚C) & annual harvest (% catchment) 10.0 OW-ON 5.0 0.0 8-Dec-94 8-Dec-95 5-Dec-05 7-Dec-96 5-Dec-06 9-Dec-91 8-Dec-92 8-Dec-93 7-Dec-97 7-Dec-98 7-Dec-99 6-Dec-01 6-Dec-02 6-Dec-03 5-Dec-04 5-Dec-07 6-Dec-00 -5.0

  44. Post-harvest cooling rate decreases with stream size 10 10 B A SummerMax SummerMax Rate of decline in average summer temperature difference from reference (˚C/yr) 1 1 Summer Mean Summer Mean 0.1 1 10 100 10 100 1000 10000 Catchment area (ha) Channel width (m) Source: Quinn & Wright-Stow 2008

  45. 30-m temp. logger 5-m temp. logger Open site temp. logger 30 m 5 m 20 m True left bank Stream channel True right bank Riparian air temperature Monitored 11 months

  46. 6 6 a a 4 4 2 2 b 0 0 Daily max. -2 -2 Air temp. differences Temperature difference (°C ) Open - 5m 5m - 30m Open - 30m Buffer width pairs Meleason & Quinn (2004, FEM 191: 365-371)

  47. Biomonitoring indicates temp is a key driver of invertebrate effects Small (shallow) streams heat rapidly Shaded headwaters protect open areas downstream Slash maintains cool temperatures Riparian forest moderates water and air temperature impact Water temperature summary

  48. 70 p = 0.005 60 50 40 30 20 Algae (mg Chl. a m-2) 10 0 H HP HC P PR N Logging and algae Boothroyd et al. 2004 For Ecol Mgmt 191: 199-213

  49. Clearfelling & algal blooms Blooms common when small streams logged Decline with shade & arrival of grazinginverts Blooms smaller but last longer on larger streams Logging periods 70 3 ) 2 2 60 - 1 50 40 Periphyton (g AFDM m 1 , 48 ha Nuisance guideline 30 2 , 200 ha 3 , 328 ha 2 0 10 0 W04 W97 W01 W93 W94 W96 W98 W99 W00 W02 W03 W92 W95 ) Logging periods 5 -2 80 4 70 Ref 496 ha 60 4, 857 ha 50 5,1657 ha Nuisance guideline Periphyton biomass (gAFDMm 40 30 20 10 0 S93 S94 S95 S96 S97 S98 S99 S00 S01 S02 S03 S04 S05 S06 S07 S08 S09 S10 W92 W93 W94 W95 W96 W97 W98 W99 W00 W01 W02 W03 W04 W05 W06 W07 W08 W09

  50. Invertebrates: Buffers reduce effects Sensitive species Richness 80 60 b b b b b 70 b 50 b b 60 b ab 40 50 a 30 40 %EPT* density Taxa /0.5m2 30 20 a 20 10 10 0 0 H HP HC P PR N H HP HC P PR N 100 nonimpaired b b b b 80 b slightly impaired IBI (% reference) 60 moderately impaired a 40 20 severely impaired 0 H HP HC P PR N Quinn et al. 2004 For Ecol Mgmt 191: 129-146

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