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

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 condition 3) ground vegetation

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 study location Level II intensive Level II Level I

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 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

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

1 st ground vegetation survey in nd ground vegetation survey in rd ground vegetation survey in 2017 Survey in each block: species and cover (Londo, 1976) of: -herbaceous species -trees and shrubs Ground vegetation survey

Results: species number 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? I. Effect of treatment

Results: species number 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 I. Effect of treatment

Results: species number 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 II. Effect of dose 2007

Results: species composition 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 I. mR-value

Results: species composition 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 II. mN-value

Results: species composition 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 III. mL-value

Results: species composition Original species composition (control blocks) Limited number of acid tolerant species typical for nutrient poor sandy soils: -Deschampsia flexuosa -Calluna vulgaris -Molinia caerulea -Vaccinium myrtillus -Vaccinium vitis-idaea -Rumex acetosella -Dryopteris dilatata -Teucrium scorodonia -Pinus nigra subsp. laricio (seedlings)

Newly established species Many species that appeared after liming, often in large numbers, are uncommon for nutrient poor sandy soils, e.g.: -Fraxinus excelsior -Circaea lutetiana -Rumex obtusifolius -Urtica dioica -Populus canescens -Ribes rubrum -Sambucus nigra -Cirsium arvense -Eupatorium cannabinum -Galium aparine -Sonchus oleraceum -Stellaria media 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) -Buddleja davidii -Cotoneaster sp. -Conyza canadensis -Senecio inaequidens

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 Conclusions

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 Problems

Any questions / remarks ?