Forest Restoration An Ecophysiological, or Seedling s Perspective

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1 Forest Restoration An Ecophysiological, or Seedling s Perspective Steven C. Grossnickle NurseryToForest Solutions 1

2 Foresters know how to grow trees! Do foresters know how trees grow? 2

3 Silvics Silvics & Ecophysiology Principles underlying the growth and development of single trees and of the forest as a biological unit. Ecophysiology Physiological and morphological processes of plants in response to the surrounding environment. 3

4 Ecophysiological Approach remedies are usually found at the whole plant level in terms of silvicultural treatments. (Kramer 1986) 4

5 Programs across North America Nursery Forestry Reclamation 5

6 Information Sources Provide practitioners and researches with a seedling s view of regeneration silvicultural practices on field performance. Book Available at NRC Press Grossnickle 6

7 Forest Regeneration Process 7

8 Seedlings can grow anywhere! 8

9 Seedlings don t always grow where we plant them! Seedling mortality primarily occurs in the initial years after planting and is due to planting stress. (Grossnickle 25) 9

10 Planting Stress The most important cause of death of transplanted seedlings is desiccation. (Kozlowski and Davies 1975) 1

11 Roots & Seedling Survival Initial Root System Size Root Growth Capacity 1 1 Survival (%) Y= ln(x); =.87 r First Year Survival (%) Y= ln(x);.71 r Root Dr y Wei ght (g) Number of New Root s ( > 1. cm) Simpson 199 Blake et al

12 Water Movement & the SPAC Water Flow = Difference in Ψ / resistance to water & vapor flow 12

13 Soil Factors Water Relative Plant Resistance Y= x-17x 2 2 ; r Ψ pd ( M Pa) Relative Seedling Resistance (%) Temperature Seedlings- New Roots Seedlings- No New Roots Relative Viscosity of Water Root Temperature ( o C) 13

14 Location of Water Uptake 14

15 Root Permeability Root Resistance (MPa µg -1 cm -2 s -1 ) New Root Area (cm 2 ) 15

16 Root-Soil Contact Relative Seedling Resistance (%) Root T emper at ur e ( o C) Planted in Aerated Water Planted in Soil 16

17 Root Confinement High 2 Seedling Resistance Low R SPAC (MPa µg -1 cm -2 s -1 ) Y= x x 2 ; r 2 = Newly Planted Seedlings (Root / Shoot) * 1/Ψ pd (g MPa -1 ) Established Seedlings 17

18 Diurnal Seedling Response. Ψ (MPa) Established Seedlings Newly Planted Seedling VPD (kpa) Time (h) Stress Low Medium High Time (h) 18

19 Severe Planting Stress Ψ (M Pa) S eedlings P lanted New Root Dry Weight (g) Day 28 Day 9 M in imum Ψ Ψ tlp Stress Low Medium High -3.5 May 4 May 9 May 2 Jun 7 Jun 3 Jul 22 Aug 5 Aug 24 19

20 No Planting Stress Ψ (MPa) New Root Dry Weight (g) Day 28 Day 12 Ψ Minimum Stress Low Medium High Jun 12 Jun 3 Jul 1 Jul 29 Aug 15 Sep 5 Ψ t lp 2

21 Planting Stress - Carry Over Effect 15 1 Annual Height Increment (cm) 1 5 Annual Growth (cm) Year 5 Year 4 Year 3 Year 2 Year Year of Growth Height at Beginning of Year (cm) Vyse 1981 South & Zwolinski

22 Planting Stress 22

23 Overcome Planting Stress by Stocktype selection in relation to site conditions. Plant hardened seedlings with high root growth capability. Prepare favorable planting sites. Plant seedlings properly. Proper timing of planting (i.e., avoiding stressful conditions). Root Growth = Coupling to Site 23

24 Forest Regeneration Process 24

25 Seedling Establishment Seedling performance depends on: Inherent growth potential (i.e. Seedling Quality - morphological and physiological attributes). Ecophysiological response to site environmental conditions, which limit or enhance that potential. 25

26 Seedling Environment 26

27 Energy Exchange 27

28 Seedling Environment Solar Radiation P n (% of Maximum) Y = (ln)x; r PAR (µmol m -2 s -1 ) 28

29 Seedling Environment Temperature Extremes Summer Temperature Hours o C 51-6 o C >6 o C Accumulated Heat Stress Kolb & Robberecht 1996 Frost Events (Days) May June July August September

30 Seedling Temperature Response 3

31 Hydrologic Cycle 31

32 Carbon Uptake & Water Loss 32

33 Seedling Environment Seasonal Rainfall Rainfall (mm) YR AVG APR MAY JUN JUL Month AUG SEP OCT Levinsson et al. 214 Rainfall (mm) MAR APR MAY JUN JUL AUG SEP OCT NOV Month 33

34 Response to Drought Gas Exchange MAX Daytime gwv (% of Maximum) Y = x exp ; r Ψ pd (MPa) -2. P n (µmol m -2 s -1 ) Y= x x x 3 ; r Ψ pd (MPa) 34

35 5 Response to Drought Growth Dry to Ψ pd -.5 MPa New Height Growth (cm) Dry to Ψ pd -1. MPa 33% Decline Julian Day 35

36 Response to Drought Lethal Level 6 5 Western Redcedar Y= x x x 3 ; r 2.82 P n (µmol m -2 s -1 ) Ψ pd (MPa) McDowell et al. 28 Survival (%) Seedling Water Potential (MPa) 36

37 Seedling Environment VPD - Drying Power of Air 7 heat is like a steroid, amplifying the atmosphere s power to suck moisture from plants, soil, rivers and human skin. Carswell 218 Vapour Pressure Deficit (kpa) % RH 5 % RH 8 % RH Average Summer Conditions Air Temperature ( o C) 37

38 . Response to VPD Water Status Y= (ln[x]); r Water Potential (MPa) VPD (kpa) 38

39 Response to VPD Gas Exchange 6 5 g wv (mmol m -2 s -1 ) Y = ln(x); r VPD (kpa) P n (µmol m -2 s -1 ) P n = ln (x); r 2 = VPD (kpa) 39

40 Response to Multiple Factors Atmospheric Response Atmospheric & Edaphic Response P n (µmol m -2 s -1 ) PAR (µmol m -2 s -1 ) VPD (kpa). P n (µmol m -2 s -1 ) PAR (µmol m -2 s -1 ) VPD (kpa). 4

41 Seedling Environment Nutrient Cycle Coastal Douglas-Fir Ecosystems N Distribution (%) Foliage Branches Stem Ro o ts Vegetation Forest Floor Soil 36 YR Old 45 YR Old Johnsen et al

42 Nutrient Cycle Are limitations an issue? 2 Natural 15 Planted (Fox et al. 26) N (g kg -1 ) 1 5 YR1 YR2 Munson and Bernier

43 Seedling Establishment Nursery Cultural Practices Quality Attributes Stocktype BR or CON Site Preparation Handling Practices Site Cultural Practices Planting Practices Vegetation Management Eco Technologies Silvicultural Systems 43

44 Seedling Establishment 1 Survival / Establishment Rate (%) Silvicultural Practices Low Medium Harsh Site Environmental Conditions High Low Medium Seedling Quality Value 44

45 Closing Thoughts Planting Stress It is real, so be aware of the issue. Establishment Phase Understand site effects on tree species ecophysiological response. Silvicultural Practices Intent to create desirable field site conditions. Seedling Quality A critical decision controlled by Foresters. 45