Forest Restoration An Ecophysiological, or Seedlings Perspective - PowerPoint PPT Presentation

Forest Restoration An Ecophysiological, or Seedling’s Perspective Steven C. Grossnickle Nursery To Forest Solutions

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

Silvics & Ecophysiology Silvics 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.

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

Programs across North America Nursery Forestry Reclamation

Information Sources Provide practitioners and researches with a seedling’s view of regeneration silvicultural practices on field performance. Book Available at NRC Press Publications @ https://www.researchgate.net/profile/Steve_ Grossnickle 6

Climate Change “…recent studies document more rapid mortality under hotter drought due to negative tree physiological responses…” (Allen et al. 2015)

Regional Shifts

Environmental Conditions

Energy Exchange

Seedling Environment - Temperature o C) 75 20 cm Maximum Seasonal Temperature ( 1 cm 50 S urface 25 0 0 600 1200 1800 2400 Time of Day Kolb & Robberecht 1996

Seedling Response – Temperature Duration, Timing & Intensity Timing Intensity 100 100 Temperature 90 Stress Resistance (%) 90 80 Drought Percent of Maximum P n 80 70 Duration & 70 60 Intensity 60 50 120 50 40 30 40 Y= (2.114 x 10 11 )10 - 0. 208x) ; r 2 0.99 100 20 30 Minutes of Exposure 10 Shoot G rowth Phase 20 80 0 10 FEB MAR MAY SEP NOV JAN APR JUN JUL AUG OCT DEC 0 60 15 20 25 30 35 40 Air Temperature ( o C) 40 20 0 44 45 47 48 50 52 54 56 58 60 Temperature ( o C) Colombo & Timmer 1992

Hydrologic Cycle

Location of Carbon Uptake & Water Loss

Response to Drought Gas Exchange Response 100 MAX Daytime gwv (% of Maximum) 90 Y= 108.52 + 1.38x exp ; r 2 0.95 80 70 60 50 40 30 6 20 2 + 0.63x 3 ; r 2 0.82 10 Y= 6.09 + 8.00x + 3.83x 5 0 0.00 -0.50 -1.00 -1.50 -2.00 4 P n ( µ mol m -2 s -1 ) Ψ p d (MPa) 3 2 1 0 -1 0.00 -0.50 -1.00 -1.50 -2.00 -2.50 Ψ pd (MPa) 15

Response to Drought Growth 50 Dry to Ψ pd -0.5 MPa 40 Dry to Ψ pd -1.0 MPa New Height Growth (cm) 33% Decline 30 20 10 0 0 1 150 175 200 225 250 275 Julian Day 16

Response to Drought Lethal Level 100 90 Survival (%) 80 70 60 50 40 30 0 -0 -1 -2 -3 Seedling Water Potential (MPa) 17

Atmospheric VPD Drying Power of Air 6 Vapor Pressure Deficit (kPa) 2 0 % RH 5 5 0 % RH 4 8 0 % RH Typical Afternoon 3 Summer Conditions 2 1 0 0 5 10 15 20 25 30 35 40 Air Temperature ( o C)

Response to VPD Water Status 0.00 2 0.46 Y= -1.07 - 0.4(ln[x]); r -0.50 Water Potential (MPa) -1.00 -1.50 -2.00 0 1 2 3 4 5 VPD ( kPa) 19

Response to VPD Gas Exchange Response 60 50 g wv (mmol m -2 s -1 ) 40 30 20 6.0 10 Y= 73.39 - 34.59ln(x); r 2 0.50 5.0 P n ( µ mol m -2 s -1 ) 0 0 1 2 3 4 5 6 4.0 VPD (kPa) 3.0 2.0 1.0 (x); r 2 = 0.56 P n = 4.97 - 1.99 ln 0.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 VPD (kPa) 20

Summer Heat & Drought  Seedlings can be exposed to limiting or ‘killing’ temperatures.  Drought comes in the form of:  Low soil water availability  High atmospheric VPD  Drought exposes seedlings to:  Water stress  Reduce gas exchange  Limited growth  Death

Forest Regeneration Process

Understanding Plantation Failure “An understanding of the causes of plantation failure is necessary if there is to be an improvement in large scale reforestation work…” Rudolf (1939)

Seedlings can grow anywhere!

Seedlings don’t always grow where we plant them! The greatest seedling mortality occurs in the initial years after planting and is due to planting stress (Grossnickle 2005).

“ The most important cause of death of transplanted seedlings is desiccation.” Kozlowski and Davies (1975)

Roots & Seedling Survival Initial Root System Size Root Growth Capacity 100 100 First Year Survival (%) 75 Survival (%) 75 50 50 25 Y= 3 6 . 8 + 14 . 4 l n ( x) ; r 2 0 . 7 1 25 2 = 0 . 8 7 Y= 4 6 . 5 + 3 3 . 0 l n ( x) ; r 0 0 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 Number of New Root s (> 1. 0 cm) Root Dr y Wei ght (g) Si mpson 1990 Bl ake et al . 1989

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

Soil Factors Water 1000 Y= - 1. 0 8 - 2 9 4 4 x - 10 0 7 x 2 ; r 2 0 . 9 4 Relative Plant Resistance 750 Temperature Relative Seedling Resistance (%) 500 500 Seedlings- New Roots 400 Seedlings- No New Roots 250 300 0 -1.25 -1.00 -0.75 -0.50 -0.25 0.00 200 Ψ p d (MPa) 100 Relative Viscosity of Water 0 0 5 10 15 20 25 Root Temperature ( o C)

Location of Water Uptake

Root Permeability Root Resistance (MPa µg -1 cm -2 s -1 ) 2.00 1.50 1.00 0.50 0.00 0 25 50 75 100 125 New Root Area (cm 2 )

Root-Soil Contact 150 Planted in Aerated Water Relative Seedling Resistance (%) 140 Planted in Soil 130 120 110 100 1 0 5.0 7.5 10.0 12.5 15.0 Root Temperat ure ( o C)

Root Confinement Limiting Water Movement into a Seedling High 20 Seedling Resistance R SPAC (MPa µ g -1 cm -2 s -1 ) 2 ; r 2 = 0.65 Y= 29.1 - 16.3x + 2.75x 15 10 5 Low 0 0. 1.00 1.50 2.00 2.50 3.00 3.50 Ψ pd (g MPa -1 ) (Root / Shoot) * 1/ Established Newly Planted Seedlings Seedlings

Diurnal Seedling Response 0.00 5 4 -0.50 VPD (kPa) 3 2 1 -1.00 Ψ (MPa) 0 400 800 1030 1230 1530 1830 Time (h) -1.50 Established Seedlings -2.00 Newly Planted Seedling -2.50 0400 800 1030 1230 1530 1830 Time (h)

Moderate Seasonal Planting Stress 0.00 4 Root Dry Wt. (g) 3 -0.50 2 Minimum Ψ (MPa) 1-yr-old Seedlings Planted 1 -1.00 0 1-Yr-Old 5-Yr-Old -1.50 F i v e -Ye a r-Ol d -2.00 On e -Ye a r-Ol d -2.50 Jul 16 Jul 29 Aug 15 Aug 29 Jun 15 Jun 30

Severe Planting Stress 0.00 Ψ 2.00 New Root Dry Weight (g) Minimum -0.50 1.50 Ψ t l p 1.00 -1.00 0.50 Ψ (MPa) -1.50 0.00 Day 28 Day 90 Seedling Planted -2.00 -2.50 -3.00 -3.50 Aug 5 Jul 22 Aug 24 May 4 May 9 Jun 7 May 20 Jun 30

No Planting Stress 0.00 Ψ Minimum -0.50 Ψ t l p -1.00 Ψ (MPa) -1.50 Seedlings Planted 1.00 New Root Dry Weight (g) -2.00 0.75 -2.50 0.50 0.25 -3.00 0.00 Day 28 Day 120 -3.50 Aug 15 Sep 5 Jul 10 Jul 29 Jun 12 Jun 30

Planting Stress- Carry Over Effect 15 100 Annual Height Increment (cm) 75 Annual Growth (cm) Year 5 10 Year 4 50 Year 3 5 25 Year 2 Year 1 0 0 0 1 2 3 4 5 0 50 100 150 200 Year of Growth Height at Beginning of Year (cm) Vyse 1981 South & Zwolinski 1997

Planting Stress- Stocktype Effect Container Bareroot

Planting Stress- Stocktype Effect Seedling Quality N= 27 Trials 100 Survival (%) 90 80 Y= 84 + 18x - 6x 2 ; r 2 0.98 Binder et al. 1990 70 0.0. 2 3 4 Shoot to Root Ratio (g DW) Mexal & Dougherty 1983

Planting Stress- Stocktype Effect Field Site Water Relations Dixon et al. 1983

Planting Stress- Stocktype Effect Field Performance N= 29 Trials N= 122 Trials

Planting Stress

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

Closing Thoughts