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Physiological ecology of understorey Physiological ecology of understorey trees in alternative managementtrees in alternative management

systemssystems

Sophie BertinSophie Bertin Maurizio Mencuccini1, John Grace1, Mike Perks2, Nigel Straw2 & Bill Mason2

1 University of Edinburgh & 2 Forest Research

PhD project Co-Sponsored from the Forest Research Innovation Fund & the Torrance Bequest for Plant Ecology

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CCF : increasingly common alternative management system for British forests

Sitka spruce : dominant commercial tree species in the UK

Limited knowledge of desirable conditions for seedling regeneration and growth under CCF

Continuous Cover Forestry & Sitka SpruceContinuous Cover Forestry & Sitka Spruce

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Main defoliator of Sitka spruce

Sap feeding insect

Prediction: climate change is likely to enhance aphid population growth and therefore declines in Sitka spruce productivity (Straw, 1995).

Green Spruce Aphid & Climate Change (I)Green Spruce Aphid & Climate Change (I)

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Green Spruce Aphid & Climate Change (II)Green Spruce Aphid & Climate Change (II)

Life cycle of the green spruce aphid

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Research QuestionResearch Question

Low light conditions

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Aphid attack

&

??

How are Sitka spruce seedling growth and survival affected by the interactions between

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General Aim and HypothesisGeneral Aim and Hypothesis

General aim

Understanding seedling tree ecophysiology within CCF systems

Hypothesis

Low light level & aphid attack = poorer Sitka spruce seedling growth and survival

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Methods (I)Methods (I)

2006: Exploratory experiments

Short-term pot-plant shade/aphid experiment, NRS nursery, Roslin

Transect investigations of natural regeneration and treated trees in CCF sites, Borders

2007-08: Detailed experiments

Full field shade/aphid experiment, Roslin

Large scale field manipulation experiment, Wales

NRSBorders

Wales

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Methods (II)Methods (II)

Block 1 Aphid A+ A- A- A+ A+ A- A- A+ A- A+ A+ A-Shade % 92 70 0 83 50 76 Key

A+ : aphid infestationBlock 2 Aphid A- A+ A- A+ A+ A- A- A+ A+ A- A- A+ A- : no aphid infestation

Shade % 76 92 83 70 0 50

Block 3 Aphid A- A+ A+ A- A+ A- A- A+ A- A+ A- A+Shade % 0 92 50 70 76 83

Block 4 Aphid A- A+ A+ A- A- A+ A- A+ A+ A- A- A+Shade % 50 70 83 76 92 0

Layout of short-term pot-plant experiment 2006

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Assessment Protocols (I)Assessment Protocols (I) Aphid population size

(Straw and Green, 2001)

Plant allometry (architecture) and needle densities

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Assessment Protocols (II)Assessment Protocols (II)

Plant Physiological measurements

Photosynthesis

Chlorophyll fluorescence kinetics

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Research OutcomesResearch Outcomes

Guidelines for natural regeneration under CCF management systems

Implications for the impact of green spruce aphids on Sitka spruce

Development of chlorophyll fluorometer techniques to assist CCF stand manipulation

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Mike Perks (NRS) Maurizio Mencuccini (UoE) Forest Research staff University of Edinburgh

AcknowledgmentsAcknowledgments