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 of 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”

What are the impacts of woodland colonisation on biodiversity and ecosystem function? Birch plots Heather plots Plots established in early 1980’s

Location of sites Kerrow Craggan Delnalyne

Example of experimental site Fence 1 5 3 2 4 6 7 8 9 10 11 12 Control heather plot Planted birch plot 5 permanently marked quadrats in each plot

Effects of birch on:  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

Effect of birch on vegetation  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 Birch plot Heather plot

Effect of birch on soil Chemical properties Significant increases in: • phosphorus • nitrogen mineralisation Significant decrease in • carbon • Soil moisture

Effect of birch on soil Physical properties Significant increase in: • bulk density Significant decreases in: • depth of organic layer

Are these changes driven by the trees? Big differences in birch growth

Are these changes driven by the trees? 80 Mineralizable N (mg/100g) 60 40 20 0 15 0 0.1 0.2 0.3 0.4 Depth of O-horizon (cm) Total basal area (m 2 ) 10 5 Delnalyne Craggan Kerrow 0 0 0.1 0.2 0.3 0.4 Total basal area (m 2 )

Enchytraeids 50000 40000 Density m -2 30000 20000 10000 0 Delnalyne Craggan Kerrow Birch Heather

Mites Oribatid mite species richness 20 Number of species . 15 10 5 Oribatid mite abundance 100000 0 Delnalyne Craggan Kerrow 80000 Mites/m 2 . Birch Heather 60000 40000 Similar results for 20000 Mesostigmata and 0 Prostigmata mites Delnalyne Craggan Kerrow

Collembola Collembola species richness 10 Number of species . 5 Collembola abundance 0 50000 Delnalyne Craggan Kerrow 40000 Collembola/m 2 . Birch Heather 30000 20000 10000 0 Delnalyne Craggan Kerrow

Soil Microbial Community - PLFAs 1.0 3000 2500 Fungal:bacterial ratio 0.8 2000 Total PLFA nmolg-1 0.6 1500 0.4 1000 0.2 500 0.0 0 Delnalyne Craggan Kerrow Delnalyne Craggan Kerrow

Soil Microbial Community - PLFAs 3.1 Shannon's diversity index 3.0 2.9 2.8 2.7 2.6 2.5 2.4 Delnalyne Craggan Kerrow

Ecosystem function: Decomposition 20 Birch Decomposition (%) . Heather 15 10 5 0 80 Delnalyne Craggan Kerrow Decomposition (%) . Wood 60 40 20 0 Delnalyne Craggan Kerrow Paper

Ecosystem function: N mineralization 1.0 Fungal PLFA: Bacterial PLFA ratio 0.8 Change in microbial 0.6 community related to change in function 0.4 0.2 0.0 0 20 40 60 80 Mineralizable N mg 100 g-1

Impacts on carbon storage? Decline in carbon storage??

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