EU Life-Environment funded project:

Re-creating woodland and heathland on slate waste in Wales

J C Williamson, E C Rowe, J R Healey, D L Jones,

P J Holliman, M A Nason

Partners: University of Wales, Bangor; Alfred McAlpine Slate; Slate Ecology Co., Pizarras-Villar del Rey

Output: Science-based guide to Best Practice for achieving the restoration of self-sustaining, semi-natural ecosystems of high conservation value

Context of the Restoration project at Penrhyn Quarry

where penrhyn lies in relation to SNPA and SSS1

conditions prog, heath, woodl

Structure of presentation

1. Broadleaf woodland creation- tree performance- soil performance

2. Heathland creation

3. Fertilizing naturally established vegetation- tree performance- invertebrate abundance and diversity

4. Bird abundance and diversity

5. Detritivore abundance and diversity

Broadleaf Woodland Creation

Aims - Tree performance To examine the effects on tree establishment and growth of improved

• water supply• nutrient supply

To assess requirements of different tree species in relation to their

• ability to fix nitrogen• seed size

Broadleaf Woodland Creation

Aims - Soil performance

• Typically, quarry sites lack topsoil, so need to design substrates for nutrient and water delivery

• Nutrient cycling needs a ‘kick start’, so need organic matter

• Develop soil biochemical predictors of longer-term above-ground success - compare planted and natural systems

Design: 3-way split-plot factorial

Main plots: 3 water-holding treatments (x 3 reps)None Clay Polyacrylamide gel

Split plots: 5 “tree” speciesAlder Birch Gorse

Oak Rowan (i.e. 2 N-fixers, 4 non-fixers; 2 small-seeded, 3 large)

x 3 nutrient supply treatmentsNone Biosolids+ Mineral NPK+trace

paper sludge slow release 15:10:10in 2 randomised complete blocksSheltered, 275 m a.s.l. Exposed, 330 m a.s.l.

Method

• Set up April 2000

• Flat areas of slate waste fenced against sheep

• Tree species planted as nursery-raised 1 year old

seedlings

• Standard 3 L hole dug for all treatments

• 5 plants per plot, in quinqunx arrangement (50 cm

spacing)

Method used for tree planting

Slates arranged tocollect rainfall

1-year oldtransplant

Soil amendments in 3 L pocket, depth 15 cm

Free-drainingcoarse slate waste

1mRoots moving towards fines

Water-holding fines

Species Alder Birch Gorse Oak Rowan

Seed size small small large large large

N2 fixer yes no yes no no

Fertilizertreatment

Basal area (mm2) Mean

No fertilizer44 5 33 6 5 19 a†

NPK 52 26 50 11 28 33 b

Biosolid-

paper mix

70 41 59 10 37 43 c

Mean 55 c 24 b 47 c 9 a 23 b 32

Results: Fertilizer effects on stem basal area after 18 months

† Main effects labeled with same letter were not significantly different (P<0.05)

Species Alder Birch Gorse Oak Rowan

Water-holdingtreatment

Basal area (mm2) Mean

No treatment 42 21 44 8 1827 a†

Boulder clay 74 33 59 11 32 42 b

PAM gel 49 18 38 8 20 27 a

Mean 55 c 24 b 47 c 9 a 23 b 32

† Main effects labeled with same letter were not significantly different (P<0.05)

Results: Water-holding effects on stem basal area after 18 months

Results: Fertilizer effects on selected soil quality predictors after 18 months

Fertilizer treatment P

value

Semi-

natural

woodland

No

fertilizer

Biosolids-

paper mix

NPK

Microbial biomassmg N kg-1

21 a† 135 b 29 a < .001 137 b

Respirationmg C kg-1.h-1

0.40 a 3.29 b 0.44 a < .001 2.63 b

Microbial diversity(Simpson's Index 1/D)

4.3 a 6.8 b 5.3 a 0.036 7.2 b

† Main effects labeled with same letter were not significantly different (P<0.05)

Conclusions - Tree performance

• N-fixers establish rapidly on slate waste even without added fertilizer

• Small-seeded tree species responded more than large-seeded species to fertilization

• Organic amendment resulted in greater tree growth than mineral NPK

• Polyacrylamide gel appears to be of little benefit

• Boulder clay greatly improved tree growth

Conclusions - Soil performance

• Organic matter (OM) addition increased soil microbial biomass, respiration and diversity, and therefore nutrient cycling, relative to other treatments

• NPK did not improve soil quality, compared with unamended slate

• Within 18 months, soil quality predictors in the OM amended treatment were similar to those of nearby semi-natural woodland soil

• Biosolid-paper mix was a very effective surrogate

Heathland creation

Three approaches were tested:

• Direct transfer of heathland turf

• Planting heather plugs

• Seeding using harvested heather sprigs or seed heads

Transferring heathland turf

pic slide

pic slide

Age (years)

Co

ver

(%)

0

25

50

75

100

125

150

175

200

225

250

275

Ericoids (e.g. heather)Graminoids (e.g. soft rush)

TARGETS TRIALS ----------------------------------->Semi-natural

heath

Old tip heath

14000(?) c.85 1 2 3 1 2 3 1 2 3 1 2 3

Not fenced

Heatherplanted

Not fenced

Heathtopsoilapplied

Sheepexcluded

Heathtopsoilapplied

Sheepand rabbitsexcluded

Heathtopsoilapplied

Ericoid cover required for Phase 1 "Heath"

Results: planting plugs and heathland turf transfer

Seeding heathland species

• Necessary when creating large areas

• Ericoids naturally establish on slate fines and clay

Trials• dried chopped ericoid sprigs applied to clay ± bark peelings as mulch (Nov 2000, Feb 2001)

• fresh seed capsules with tackifier and geotextile mulch (Nov 2001)

• dried and ‘smoked’ seed capsules with tackifier and geotextile mulch (May 2002)

Results: Heather seeding

• Seedling survival low 1-6 m-2

• Bark mulch had no effect

• Application rate had no effect (0.2 vs. 0.6 kg m-2)

• Applying fresh seed capsules with geotextile mulch did not improve survival

• Too early to say if ‘smoking’ has helped

• Good germination in seed trays

Conclusions

• Planting heather gives no advantage over spreading heathland turf

• Excluding sheep speeds the establishment of heather cover and the development of a community similar to NVC H10a (target)

• Excluding rabbits results in excessive growth of graminoids and a floristic trajectory diverging from target heathland

• Grasses may be important to early heather survival

Fertilizer addition to naturally established trees

To test if: • Revegetation can be accelerated

• Leaf invertebrate abundance and diversity can be enhanced

• Other environmental factors influence invertebrate communities

Experimental set-up

10 fert. 10 un fert.

20 birch(10 pairs )

10 fert. 10 un fert.

20 w illow(10 pairs )

40 quarry trees

10 un fert.

10 birch

10 un fert.

10 w illow

20 woodland trees

60 trees

NPK fertilizer (15:10:10) added at 175 kg N/ha/y for 2 y

Tree response to fertilization

Mean shootextension, cm

Birch Willow

Unfertilized 12.9 (1.8) 11.6 (2.4)

Fertilized 21.2 (2.0) 20.0 (2.3)

P (Paired T-test) <0.001 < 0.05

Leaf invertebrate abundance and diversity

0

0.1

0.2

0.3

0.4

May June July

Month

Men

hin

ick'

s In

dex

V

alu

e

Q

QF

W

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

May June July

Month

No.

aphi

ds p

er c

m fo

liage

W

Q

QF

• Aphid abundance responded to fertilization in July 2000 and in May-July 2001

• In 2001, species richness was reduced by fertilization

• Less mobile groups such as Lepidoptera did not respond to fertilization and isolation distance was important

2000

2001

•Total bird species, but notably passerines, were fewer in the quarry compared to adjacent semi-natural habitats

•Total number of detections and species richness significantly increased with age of slate waste tip (25 - 85 y)

• In the quarry, %tree cover was very important toredstarts (r +0.47), agood indicator spp.

Bird Survey - Point Sampling

Redstart (Phoenicurus phoenicurus)

Invertebrates - Litter bag sampling

• Total numbers in the quarry were 50% less than in adjacent semi-natural habitats

• Species richness was positively correlated with quarry tree diversity and % cover of vegetation, ericoids and mosses

• Acarina (mites) numbers were the most sensitive to% tree cover (r +0.47), agood indicator group

Acarus spp.

Overall Conclusions

• Woodland establishment was enhanced by organic fertilizer produced from locally available, free wastes

• In situ boulder clay subsoil was necessary as a water-holding treatment for trees and freely available

• Heathland creation by direct transfer of turf was successful

• Low-cost heathland creation by seeding was problematic. A nurse grass may improve success

• Fertilizing naturally established trees increased tree growth and invertebrate abundance but not diversity

• Tree cover was important to indicator bird and detritivore species

• Strategic intervention by planting and seeding with local provenance materials will XXXXX

Overall Conclusions