Background to the tree and soil study investigations

Soil & Trees

“We know more about the movement of celestial bodies than about the soil underfoot”

Leonardo da Vinci

Lots of tree health issues

Oak decline

Phytophthora sp.

Forest declines – global

Virulent new pathogens – biosecurity Ash die-back

Most appear linked to water and/or soil

Oak decline of particular concern

AOD distribution: 1997-99 episode

AOD distribution: 2006 – 2016 episode

- Acute oak decline (AOD)

Crown morphology & oak decline

Are there clues to a key factor underlying the condition in the pattern of crown break up?

Loss of lateral shoots/bud – first sign of decline

• Indicating a link to water? • Hydraulic limitation or hormonally mediated

• All points towards water Root function and soil

Yoder (1997); Rust & Roloff (2002) [hydraulic limitation]

Royal Parks study – Acute Oak Decline (AOD)

2009 started preparing for Royal Parks study

Investigate link with soil biology, chemistry and structure

Apply novel biological treatments

ACT crown application ACT ground application Woodchip mulch Control

Introduce expert arboricultural observation into study

Other TEPr studies:

Massaria disease of plane

1. Kensington Gardens (Royal Parks), London – since 2013 2. Islington Borough Council, London – since 2011

Oak decline – in conjunction with Natural England and landowners

1. Burghley House, Stamford – since 2013 2. Eastnor Castle Estate SSSI, Herefordshire – since 2017 3. Moccas Park SSSI, Herefordshire – since 2018 4. Brampton Bryan SSSI, Herefordshire – since 2018

Ink stain disease of chestnut (Phytophthora cinnamomi)

1. Greenwich Park (Royal Parks), London – since 2017

Independent study – Oak decline, Guildford Borough Council

Back over to Simon

Oak decline crown condition scoring system

Crown density (Innes system) 20 point scale

Drought stress crown indicators – Dead twigs in canopy

– Small branch mortality

Crown Integrity - Breakup – fragmentation

Leaf health & condition & size: green – chlorotic

Number of previous decline episodes

Notes on crown decline morphotype

Results Royal Parks study

Interpretation of results

Highly significant effect - P<0.01

Foliar ACT (green) Instant effect

Effect on rhizosphere microbiome

Woodchip mulch (purple) Similar microbiome to ACT

Increase organic matter

Needed re-applying

Ground ACT (blue) Similar overall magnitude of effect

Slower acting

Control (red) Episodic nature of oak decline

Timing of study - context

Control of oak mildew Induced resistance

Microbiostasis

Foliar feeding - absorption of micronutrients & humic acids

Re-introduction of longer distance exploration mycorrhizal morphotypes

Micorrhizing bacteria

Ameliorated tree microbiome Improved plant growth processes & vigour

Improved stress resilience

Compost tea application with oak – what might results be showing?

Oak decline – analysing crown decline morphology Drobyshev et al, 2006 - Temporal Mortality Pattern of Pedunculate Oaks in Southern Sweden

Dendrochronological analysis of dead, declining and healthy trees

Identified two different dendrochronological phenotypes

Observations of crown decline morphology during TEPr and GBC oak decline studies

Two broad decline morphotypes that confirm Drobyshev’s phenotypes

Confirmed by tree ring analysis

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‘Episodic’ (boom & bust) decline phenotype

‘Slow & steady’ decline phenotype

Royal Parks Study

Differential response of different decline phenotypes to treatments

ACT use helped gain a better understanding of the nature of decline with different decline phenotypes

‘Episodic’ (boom & bust) Larger leaves

Tendency towards longer shoot extension growth

Sudden ‘slow downs’ in growth and peripheral shoot die-back

Increased incidence leaf chlorosis during decline phase

Noticeable cycles of decline and recovery

‘Slow and Steady’ Small, leathery leaves

Bunched growth

Reduced vigour – slow growth

Drought adaptations?

Characteristics of two different decline morphotypes

Bunched growth – recovering oak treated with woodchip mulch at Burghley house