Effects of liming on the ground vegetation of a Corsican pine stand in Flanders, Belgium

1. Effects of liming on the ground vegetation of a Corsican pine stand in Flanders, Belgium Arne Verstraeten Meeting of the ICP Forests Expert Panel on Biodiversity and Ground Vegetation, 17–19 June 2013, Freising, Germany

2. Background • Initiative of Peter Roskams and Bruno De Vos to do experimental research in addition to Level I and Level II ~ methods to remediate acidification / nutrient deficiency • Evaluate the effect of different liming treatments (products and dose) on: 1) soil chemistry 2) crown condition3) ground vegetation

3. Study area • The study was conducted in ‘Het Pijnven’, a forest complex in the Campine ecoregion of Flanders • In a Corsican pine stand (Pinus nigra subsp. laricio) ±80 years old • Regularly managed (thinning) • On a nutrient poor, acidic sandy podzol • Nearby 1 Level II plot and 4 Level I plots Level II intensive Level II Level I study location

5. Setup of the experiment • 5 products were selected for liming: • dolomite (1) • LD slags (2) • marble grinding powder (3) • paper sludge (4) • ‘foam lime’ (waste product from sugar refineries) (5) • Each applied as a single dose (a) or double dose (b) • A ‘single dose’ ~ acid binding capacity of 3.000 kg dolomite ha-1 • In a random block design with: • 36 blocks (30 x 30 m) from a 180 x 240 m grid • 3 repetitions per treatment + • 6 control blocks (0) • Buffer zone of 2 m at the edge of each block • Applied in 1999

6. Random block design Legend Reserve Affected by wind throw (not selected) Corsican pine stand

7. Ground vegetation survey • 1st ground vegetation survey in 2002 • 2nd ground vegetation survey in 2007 • 3rd ground vegetation survey in 2017 • Survey in each block: species and cover (Londo, 1976) of: • herbaceous species • trees and shrubs

8. Results: species number I. Effect of treatment 1) Herbaceous species • Species number increased for all treatments after 3 years and apparently more after 8 years compared to control plots • Slightly lower species number for treatments 4 (paper sludge) and 5 (‘foam lime’) when applied as a single dose • More species at control plots in 2007: Colonizing from treated blocks or observer effect? 2002 2007

9. Results: species number I. Effect of treatment 2) Trees and shrubs • No increase of species number after 3 years. A clear increase after 8 years, but also at the control plots • No clear differences between individual treatments 2002 2007

10. Results: species number II. Effect of dose • Number of herbaceous species was slightly higher in plots treated with a double dose than in plots with a single dose • No difference for the number of tree and shrub species 2007 2007

11. Results: species composition I. mR-value • Mean R-value of Ellenberg for British plants (Hill, 1999) weighted by the cover of each species • mR-value increased with nearly 1 unit in plots treated with a single dose and nearly 2 units in plots treated with a double dose • Shift towards less acid tolerant species • Quite large differences between treatments, highest mR for 1, 2 and 3 2007 2007

12. Results: species composition II. mN-value • Mean N-value of Ellenberg weighted by the cover of each species • mN-value also increased, indicating a shift towards more nitrogen demanding species • limited differences between treatments, highest mN for 1, 2 and 3 2007

13. Results: species composition III. mL-value • Mean L-value of Ellenberg weighted by the cover of each species • mL-value also increased, indicating a shift towards more light demanding species • Limited differences between treatments • Combined effect of liming and thinning? 2007

14. Results: species composition Original species composition (control blocks) Limited number of acid tolerant species typical for nutrient poor sandy soils: • Deschampsiaflexuosa • Calluna vulgaris • Moliniacaerulea • Vacciniummyrtillus • Vacciniumvitis-idaea • Rumexacetosella • Dryopterisdilatata • Teucriumscorodonia • Pinusnigra subsp. laricio (seedlings)

15. Results: species composition Newly established species Many species that appeared after liming, often in large numbers, are uncommon for nutrient poor sandy soils, e.g.: • Fraxinus excelsior • Circaealutetiana • Rumexobtusifolius • Urticadioica • Populuscanescens • Ribesrubrum • Sambucusnigra • Cirsiumarvense • Eupatorium cannabinum • Galiumaparine • Sonchusoleraceum • Stellaria media

16. Results: species composition Exotic species Also a number of exotic species managed to settle after liming: • Aralia elata (among the first recordings in Flanders in the wild) • Buddlejadavidii • Cotoneaster sp. • Conyzacanadensis • Senecioinaequidens

17. Conclusions • Liming increased the species number of herbaceous plants, trees and shrubs • More species of neutral/alkaline conditions and more nitrogen demanding species • Several exotic species established • Impact of double dose > single dose • Treatments 1, 2 and 3 > treatments 4 and 5, probably indicating a faster turnover

18. Problems • An initial ground vegetation survey should have been made to register the situation before liming • 3 repetitions is not enough to show significant differences. It would have been better to study less treatments and take more repetitions per treatment • Possible observer effect: probably better recognition of species by the 2007 team compared to the 2002 team

19. Any questions / remarks ?