EU Life -Environment funded project: Re-creating woodland and heathland on slate waste in Wales

1. 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

2. Context of the Restoration project at Penrhyn Quarry where penrhyn lies in relation to SNPA and SSS1 conditions prog, heath, woodl

3. 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

4. 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

5. Broadleaf Woodland CreationAims - 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

6. Design: 3-way split-plot factorial • Main plots: 3 water-holding treatments (x 3 reps) • None Clay Polyacrylamide gel • Split plots: 5 “tree” species • Alder Birch Gorse • Oak Rowan • (i.e. 2 N-fixers, 4 non-fixers; 2 small-seeded, 3 large) • x 3 nutrient supply treatments • None Biosolids+ Mineral NPK+trace paper sludge slow release 15:10:10 • in 2 randomised complete blocks • Sheltered, 275 m a.s.l. Exposed, 330 m a.s.l.

7. 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)

8. Method used for tree planting 1-year old transplant Slates arranged to Free-draining collect rainfall coarse slate waste Soil amendments in 3 L pocket, depth 15 cm Roots moving towards fines 1m Water-holding fines

9. Results: Fertilizer effects on stem basal area after 18 months † Main effects labeled with same letter were not significantly different (P<0.05)

10. Results: Water-holding effects on stem basal area after 18 months † Main effects labeled with same letter were not significantly different (P<0.05)

11. Results: Fertilizer effects on selected soil quality predictors after 18 months † Main effects labeled with same letter were not significantly different (P<0.05)

12. 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

13. 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

14. 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

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17. Results: planting plugs and heathland turf transfer

18. 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)

19. 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

20. 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

21. 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

22. Experimental set-up NPK fertilizer (15:10:10) added at 175 kg N/ha/y for 2 y

23. Tree response to fertilization

24. Leaf invertebrate abundance and diversity 2000 • 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 2001

25. Bird Survey - Point Sampling • 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 to • redstarts (r +0.47), a • good indicator spp. Redstart (Phoenicurus phoenicurus)

26. 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), a • good indicator group Acarus spp.

27. 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

28. Overall Conclusions • 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