Woodland regeneration: impacts on biodiversity and below ground - - PowerPoint PPT Presentation

Woodland regeneration: impacts on biodiversity and below ground processes.

Ruth Mitchell (and the work of many others)

The importance of increasing tree cover

Scottish forest strategy: “increase woodland cover from 17.1 to 25% cover.” Cairngorm National Park Plan: “Enhance the condition

• f existing woodland cover and expand to develop

habitat networks that complement the landscape character and other land-uses.” Cairngorms National Park Forest and Woodland Framework: “Encourage full range of forest ecosystems from valley floor to natural altitudinal tree-line in targeted areas and the re-development of woodland types that have declined”

Birch plots Heather plots Plots established in early 1980’s

What are the impacts of woodland colonisation on biodiversity and ecosystem function?

Location of sites

Kerrow Craggan Delnalyne

1 2 3 4 5 6 7 8 9 10 11 12

Control heather plot Planted birch plot 5 permanently marked quadrats in each plot

Example of experimental site

Fence

• Above ground: Vegetation
• Soil chemistry
• Soil physical properties
• Below ground:– Mites, Enchytraeids, Collembolla, soil

microbial community

• Ecosystem processes: decomposition, nitrogen

mineralization

• Ecosystem services: carbon storage

Effects of birch on:

Heather plot Birch plot

• Significant decline in species number
• Significant decline in species richness
• Change in species composition:

loss of Calluna increase in Vaccinium and mosses in birch plots no increase in grass cover

Effect of birch on vegetation

Effect of birch on soil

Significant increases in:

• phosphorus
• nitrogen mineralisation

Chemical properties Significant decrease in

• carbon
• Soil moisture

Physical properties

Effect of birch on soil

Significant increase in:

• bulk density

Significant decreases in:

• depth of organic layer

Big differences in birch growth

Are these changes driven by the trees?

5 10 15 0.1 0.2 0.3 0.4 Depth of O-horizon (cm) Total basal area (m2) 20 40 60 80 0.1 0.2 0.3 0.4 Mineralizable N (mg/100g) Total basal area (m2) Delnalyne Craggan Kerrow

Are these changes driven by the trees?

Enchytraeids

10000 20000 30000 40000 50000 Delnalyne Craggan Kerrow Density m-2

Birch Heather

Mites

5 10 15 20 Delnalyne Craggan Kerrow Number of species .

Birch Heather Oribatid mite species richness

20000 40000 60000 80000 100000 Delnalyne Craggan Kerrow Mites/m2 .

Oribatid mite abundance

Similar results for Mesostigmata and Prostigmata mites

Collembola

Collembola abundance

10000 20000 30000 40000 50000 Delnalyne Craggan Kerrow Collembola/m2 .

Collembola species richness Birch Heather

5 10 Delnalyne Craggan Kerrow Number of species .

Soil Microbial Community - PLFAs

500 1000 1500 2000 2500 3000 Delnalyne Craggan Kerrow Total PLFA nmolg-1 0.0 0.2 0.4 0.6 0.8 1.0 Delnalyne Craggan Kerrow Fungal:bacterial ratio

Soil Microbial Community - PLFAs

2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 Delnalyne Craggan Kerrow Shannon's diversity index

Ecosystem function: Decomposition

Wood

5 10 15 20 Delnalyne Craggan Kerrow Decomposition (%) .

Paper

20 40 60 80 Delnalyne Craggan Kerrow Decomposition (%) .

Birch Heather

Ecosystem function: N mineralization

0.0 0.2 0.4 0.6 0.8 1.0 20 40 60 80 Fungal PLFA: Bacterial PLFA ratio Mineralizable N mg 100 g-1

Change in microbial community related to change in function

Impacts on carbon storage? Decline in carbon storage??

Carbon dynamics

Measurement of dissolved organic carbon (DOC): DOC concentrations highest under planted pine Measurement of root production and disappearance: Maximum root production in summer, related to soil respiration and soil temperature Measurement of CO2 released from the soil: Soil respiration is unaffected by planting Recording the weather: Relate changes to environmental changes

Carbon dynamics

Effect of tree planting on carbon budget?

Understanding the mechanisms

The role of the ground flora in driving changes: Removal of early or late successional ground flora species. The role of litter in driving changes: Addition of extra litter to increase rate

• f change.

Interactions between grazing and tree colonisation?

Possible impacts on:

• Decomposition/nutrient cycling
• Ground flora interactions
• Ticks

Early days – only 8 years!

Conclusion

Birch colonisation drives changes in:

• Communities: above ground & below ground
• Soil: chemistry & physical properties
• Ecosystem processes: decomposition & N mineralisation
• Ecosystem services: carbon storage
• Rate of change very slow
• Mechanisms behind these changes still unclear
• Interactions with grazing?

Thank you

Rob Brooker, Colin Campbell, Clare Cameron, Steve Chapman, Lisa Cole, Lucy Gilbert, Richard Gwatkin, Alison Hester, Richard Hewison, Kenny Hood, Graham Osler, Robin Pakeman, Jasmine Ross, Louise Ross, Adam Vanbergan.

Ruth.Mitchell@hutton.ac.uk