Genetic improvement of ash in British forestry:

Floral Diversity of Ash-Fraxinus excelsior

Jo Clark

National School of Forestry

University of Central Lancashire

joruthclark@hotmail.com

Introduction

UK lowest forestry cover in Europe except Ireland (11%)Shift away from coniferous plantations to broadleaves, higher grant ratesInflux on non native, non adapted materialAsh is second most commonly planted hardwood Prone to forking and poor form without proper silvicultureNeed for tree improvement on hardwood speciesReduction in rotation time and better form

Problems With Growing Quality Ash

Ash bud moth Prays

fraxinella

Ash canker Nectria

galligena

Frost damage

Set up in 1991 to improve the quality of planting stock available to the forester

Comprised of landowners, academics and interested parties

Preferred improvement technique that of the Breeding Seedling Orchard – BSO (Barnes 1995)

BIHIP – The British and Irish

Hardwood Improvement Programme

Stages in a Traditional Tree Improvement

Programme

1. Identification of phenotypically superior (plus) trees

2. Collection of reproductive material – either seed or scion

3. Establishment of progeny trials4. Selection of best performing

individuals for seed orchard establishment

5. Orchard of ‘improved’ seed bearing trees

Traditional Vs BSO Approach

Plus Tree Selection

BSOProgeny Trial

and Seed Orchard

20 Years

Improved Seed in 20

Years

Plus Tree Selection

Progeny Trial

Seed Orchard of Proven

Individuals20

Years

20 Years

Improved Seed in 40

Years

Plus Tree

Selection

Ash BSO Design and Layout

36 families of half sibs

4 orchards of replicated units varying from

720 to 1296 trees

Randomised block design with double buffer

row

Not all families are present in each orchard

4264 trees in total

BSO Assessment:Form

Major Kink

Classic Fork

Severe Sweeps

Perfect Tree

Mean Height of Families Recorded at Four BSOs in

2001

100.00

150.00

200.00

250.00

300.00

350.00

400.00

450.00

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Family

Hei

ght (

cm)

Little Hidden Farm

Mulgrave

Little Wittenham

Scarr

1 2 4 5 9 10 12 13 14 16 18 20 21 22 25 26 33 34 35 36

1

4 5

9 20 22 34 36

33

Family Performance for Height

0

50

100

150

200

250

300

350

400

450

30 19 34 23 17 1 36 10 15 13 9 14 7 20 21 26 22 6 18 11 2 12 25 33 35 8 24 31 16 29 4 28 5 3 32 27

Family

Hei

ght

(cm

)

Ht 1996 96-98 98-2001

What to Rogue?

How many trees should be left?

Should we select individual trees, ie,

the top 150 individuals?

Or should we select the top families?

What about gender?

Genetic Gain Calculations for Height

Top 150 trees

Top 150 trees of 20 common families

Top 30 families

Top 10 families

Top trees of top 30 families

Scarr 44.8 33.5 1.4 10.85 40.12Mulgrave Estate 7.25 7.25 0 0.95 7.2Little Wittenham 28.89 9.9 1.62 6.75 26.19Little Hidden Farm 24.3 9.36 0 5.94 21.6

Scarr = 32 familiesMulgrave Estate = 21 familiesLittle Wittenham = 36 familiesLittle Hidden Farm = 27 families

Floral Biology of Ash

Wind pollinationA polymorphous species exhibiting a continuum of gender

Staminate flowers

Pistillate flowers

True Hermaphrodite

Hermaphrodite Flowers

Anther

Filament

Stigma

Style

Predominantly hermaphrodite flowers with some pure male inflorescences

Predominantly Male Flowers

Predominantly Female Flowers

Male Inflorescence With the Terminal Flower

Female

Seed Development

Questions Pertaining to Gender

1. What proportion are male and female?

2. Do they change sex as they age?

3. Are male trees bigger than female trees?

4. On a hermaphrodite, do male flowers appear earlier than female to prevent self pollination?

5. Do female trees show a higher degree of forking?

6. How much seed does a true hermaphrodite produce?

Flower Ratios Recorded at the

Scarr BSO in 2002 and 2003

0%

4%

32%

57%

7% 9%

8%

31%39%

8%5%

Female

Female (h)

Hermaphrodite

Male

Male + h

Male (t)

2003

589 trees

2002

170 trees

Gender Answers

Average height of all females = 414cmAverage height of all males = 410cmMale flowers appear up to one month earlier than female flowers preventing self fertilisationAverage forks per female tree = 0.97Average forks per male tree = 0.80Huge variation in seed production by hermaphrodites