1. Extinction debt and colonization credit in highly fragmented forest landscapes Nitra, 27.05.15 Jens Kolk & Tobias Naaf

2. Question: Do historical land cover changes influence present-day plant species richness of temperate deciduous forests? Dramatic changes: Extinction debt and colonization credit Introduction 2000 – 2012 Brazil 1780 – 1880 Germany, Prignitz Data according to Hansen et al. 2013 Kolk & Naaf 2015, Biol. Cons. 182

3. Extinction debt Time-delayed extinctions, debt to be paid in future Habitat loss / fragmentation New equilibrium Extinction debt Relaxation time Time Species richness Where are we right now? ED not paid at all? ED paid half? ED paid completely? [adapted from Kuussaari et al. 2009, TREE 24]

4. Colonization credit Time-delayed colonization, credit depleted in the future Where are we right now? CC still there? CC depleted half? CC depleted completely? Colonizatio n credit Relaxation time Time Species richness Habitat creation New equilibrium [adapted from Kuussaari et al. 2009, TREE 24]

5. Landscape level scheme Richness in equilibrium habitat Colonization credit Time Species richness Ancient forest Post-agricultural forest Habitat creation Extinction debt Habitat fragmentation Raw difference Ancient forest: Continuously forest since at least 1780 Post-agricultural forest: Recently established on agricultural land

6. Study area Flat terrain Intensive agriculture 5% deciduous forest cover Main deciduous tree species –Oak (Quercus robur) –Beech (Fagus sylvatica) –Alder (Alnus glutinosa) ©Neuenhausen-prics.de ©Groundhopping-Merseburg

7. Land use history Georeferencing ~ 350 ticks Rectification Overlay with 2008 Aerials + TK25 map Schmettau Map 1767-1787 Digitize and classify forests Prussian Gov. Map ca. 1880

8. 1780 Large areas covered with deciduous forests Approx. 1000 Patches 32% cover

9. 2008 92% Loss 6000 Patches = Fragmentation 5% cover –36% ancient –64% post- agricultural

10. Extinction debt of forest specialists in ancient forests

11. Extinction debt Land use history data Specialists occurrence in 104 patches Hypothesis: Strong relationship with historical patch configuration Species richness Patch area Patch connectivity Weak relationship with present- day patch configuration [adapted from Kuussaari et al. 2009, TREE 24] Convallaria majalis Sanicula europaea Paris quadrifolia

12. ED: Results Present day configuration always explains SR better However, historical connectivity significant β = 0.12, P = 0.023 P < 0.001 n.s. Forest specialists richness dependent on present-day area and connectivity Kolk & Naaf 2015, Biol. Cons. 182 Method: Negative binomial GLM

13. ED: Discussion Extinction debt almost paid Historical connectivity last glimpse of ED Massive area loss in short time Fragmentation after 1880 1780 1880 2008 1780 1880 2008 Deciduous forest area Number of Patches

14. ED: Conclusions Rapid payment of extinction debt Habitat loss / fragmentation New equilibrium Extinction debt Relaxation time Time Species richness Where are we right now? ED not paid at all? ED paid half? ED paid completely? [adapted from Kuussaari et al. 2009, TREE 24] ED paid completely! (almost)

15. Colonization credit of forest specialists in post-agricultural forests

16. Colonization credit Specialists in 110 post-agricultural patches We now know: Extinction debt largely paid Predict SR using the ancient patches Hypothesis: Species richness Time, Patch connectivity Observed richness in post-agricultural forest patches Predicted richness from ancient equilibrium patches Colonization credit

17. CC: Results Mean colonization credit 4.7 species Up to 9 in highly isolated patches Credit for specialists was not smaller in older patches P = 0.341 P < 0.001

18. CC: Conclusions Recovery may take several centuries (if ever) Where are we right now? CC still there? CC depleted half? CC depleted completely? Colonizatio n credit Time Species richness Habitat creation New equilibrium [adapted from Kuussaari et al. 2009, TREE 24] CC still there! CC remains

19. Summary Question: Do historical land cover changes influence present-day plant species richness of temperate deciduous forests? Yes, mainly due to colonization credit Extinction debt may be paid rapidly Colonization may take a long time Land use history is important

20. Thank you for your attention!