Have introduced coniferous trees positive or negative effect on biodiversity?

Transcription

1 Have introduced coniferous trees positive or negative effect on biodiversity? Ole Reidar Vetaas, prosjekt leder, Institutt for Geografi Jan Håkon Vikane (PhD, NFR UiB) Heidi I. Saure og (PhD, NLA, UiB)

2 Why introduce alien coniferous trees to Norway Norwegian west-coast during1800-century : poverty, no forest, and lack of fuel wood

3 Climate change Winter Temperature o C Why Enhanced + Land-use Spread? Winter Precipitation 9 18% Properties with the introduced species Bjerknes Centre for Climate Research: Projection for western Norway

4 Introduced Mountain pine and Dwarf pine (Pinus mugo coll) Intra-continental from the Pyrenees and the Alps

5 Iinter-continental: Sitka spruce from Sitka in Alaska to Westren Europe and NORWAY Picea sitchensis

6 2.1 o C Bjerknes Centre for Climate Research: Projection for western Norway Alaska More winter rain higher winter temperature Sitka 6.5 o C Troms 3.0 o C Florø 7.1 o C 11.6 o C Utsira7.4 o C California West coast species that prefer mild winter and high rainfall

7 Research question Where does Sitka manage to establish? Is wet mild winter climate an advantage? Do Sitka and Dwarf / Mountain pine have an effect on the biodiversity of? Vascular plants Mosses Beetles Spiders

8 PCM A2 Leaf Area Index Pinus mugo Picea sitchensis

9 Sitka LAI composition At the end of the HadCM3-A2 scenario percentage of Sitka Spruce leaf coverage relative to all other species. West Norway and the mountains are where Sitka Spruce has a higher coverage relative to other species. HadCM3-A2

10 PhD-stud Jan H. Vikane: Populationdynamic of Picea sitchensis heathland Tagged more than 200 individuals at 8 localities in Western Norway At every individual different performance was measured

11 Patchy establishment in heathland PhD-stud Jan H. Vikane: Populationdynamics of Picea sitchensis in heathland

12 Many small plantations High number of cones Very short juvenile phase < 10years Sitka spruce (Picea sitchensis) Tolerate grazing

13 Results on Sitka establishment moss no effect heather inhibits % cover bryophytes % cover heather present Pre/ab sitka absent 44 Mean Mean±SE present Pre/ab sitka absent Mean Mean±SE

14 Results on Sitka establishment Juniperus (Einer) inhibits % cover Juniperus communis present Pre/ab sitka absent Mean Mean±SE

15 Degenerated Proportion seedling establishment vegetation Control Treatment disturbance removed vegetation Disturbed sites have much higher recruitments than undisturbed in all stages of heather. Mature Pioneer 0.18 Proportion seedling establishment Control vegetation disturbance Treatment removed vegetation Proportion seedling establishment Control vegetation disturbance removed Treatment vegetation

16 Climate experiment: moisture manipulation outdoor Sitka seedlings thrive under many different moisture regimes Extreme cold winter ruined the extended growingseason due to mild winters

17 Effects on biodivesity

18 Effect on biodivesity Sitka plantation Pine plantation

19 Plot richness: plot size =grain or resolution Transect by H. SAURE: The impact of naturalised Sitka spruce on species number in heathland Canopy- Transect 0.25 m x 0.25 m = m m 2 5 VETAAS: pine forest mainland and islets 1, 25, 100m 2, and islands >1000m 2 Spider and beetles traps

20 Reduced species richness of vascular plants 4 Species number in natural plots MINUS species in plots with Sitka spruce 1m m 2 25m 2 0 (-1) No effect = no difference 100m ln (plot size +1)

21 Spiders, Beetles, and mosses at 1-square metre resolution. Spider under Sitaka-canopy vs open in forest with Sitka spruce spread: no difference (8.4 vs 8.8) Beetles under Sitka-canopy vs open in forest with Sitka spruce spread: no difference (5.16 vs 5.54) Mosses under Sitka-canopy vs open in forest with Sitka spruce spread: no difference (8.5 vs 7.24)

22 HEATH LAND: COMPARING OPEN HEATHER WITH SITKA AND PINE Heidi I. Saure (PhD, NLA, UiB)

23 Transect reminder.. Sitka/Pinus North 2m Sitka/Pinus South 2m Comparing Sitka/Pinus Open 2m

24 13 Box & Whisker Plot plants sinoall and vs. mosses siopall sinoall siopall Canopy vs outside Mean Mean±SE Mean±1.96*SE

25 Mosses and Vascular plants along transect from trunk Sitka Pinus, furu Canopy Canopy number of species number of species distance from Sitka stem distance from Sitka stem meters GAM smoother GLM: p< % Deviance explained

26 Moss no./ transect plot MOSS Vasc no./tr.plot VASCULAR PLANTS sitka N&S pinus N&S si pi SITKA PINUS, furu

27 On which islets are there most plant species? Native pine forest Sitka spruce Dwarf and Mountain pine (+ a few sitka

28 Difference in total number of species on islets corrected for difference in size of the islests (area in 1000 m 2 ) Native pine Introduced pine t = , df = 50, p-value <

29 Dwarf and Mountain pine (+ a few Sitka spruce) Native pine forest >> Null hypothesis rejeted more species on islets with introduced forest (geographical factors such as area and spatialautcorreleation were adjusted for)

30 CONCLUSION and RISK ASSESSMENT Species richness is VERY scale dependent Sitka spruce has impact on diversity at fine scale, but currently not at landscape scale. Candidate for the black list because of: High spread, fast growth, and big impact when it dominates, as it may do in the future. Dwarf pine- and Mountain pine positive effect on plant diversity on islands. not candidate for the black list.

31 Fairly good Not good for future

32 GOOD Thank you for your attention Spøsmål, takk