1. Virtual Field Trip Heathlands and Roads © Amy Rogers © Carl Corbidge

2. You are going to be learning about a very important habitat – lowland heathland. You will learn about a case study of the A3 Road that passes through the Devil’s Punch Bowl heathland in Surrey. You will be collecting data and conducting analyses to investigate how the road is affecting the ecology of the heathland. What are you going to do? © Amy Rogers

3. You will be finding out: what nitrogen deposition is, and why it is a problem for heathlands; What habitat fragmentation is and why is it a problem for habitats such as heathland; how to identify common heathland plant species; how to collect vegetation data using quadrats; how to analyse data (graphically and statistically) to investigate the effect of nitrogen deposition on heathland vegetation. Objectives

4. Over the past few decades there has been an increase in emissions of man-made nitrogen-containing compounds into the atmosphere, notably nitric oxide (NO), nitrogen dioxide (NO 2 ) and ammonia (NH 3 ). The nitrogen contained in these compounds can leave the atmosphere and enter the biosphere – this process is known as nitrogen deposition. What is nitrogen deposition? Atmosphere Biosphere

5. Nitrogen-containing compounds such as nitrous oxides (NO x ) and ammonia (NH 3 ) can enter the biosphere by both wet (i.e. via precipitation) and dry deposition (i.e. the direct deposition of gases) = nitrogen deposition. N2N2 NH 3 & NO X Naturally occurring nitrogen gas (N 2 ) only enters the biosphere after being fixed by micro-organisms or lightning.

6. Why is nitrogen deposition a problem for heathlands? Healthy heathland soils are nutrient poor – this allows plants like to heather to out-compete faster growing plants (such as grasses and bracken) and dominate the heathland. If soil nutrient levels increase, faster growing species (grasses, bracken, birch trees) may invade and turn the heathland into a different habitat (woodland). Nitrogen deposition can increase soil nutrient levels and so threatens the existence of the heathland habitat.

7. Which of these sources was the greatest emitter of nitrous oxide (NO x ) in England and Wales in 2005? Other Sources Industry Road Transport Domestic & Commercial 10%21%51%18% Source: Data for Neighbourhoods and Regeneration (http://www.data4nr.net/resources/503/) Nitrogen deposition: Nitrous Oxide (NO x )

8. In 2007, 289 thousand tonnes of ammonia were emitted in the UK (excluding natural sources). What percentage of these emissions came from agriculture 51%71%81%91%61% Nitrogen deposition: Ammonia (NH 3 )

9. The main aim of our investigation is to understand the impact roads such as the A3 can have on heathland habitats. We will be investigating both the impact of anthropogenic nitrogen pollution from traffic emissions, and the impact of habitat fragmentation. The aim of our investigation © Lauren Gough

10. Section A Introducing the case study site - Devil’s Punch Bowl SSSI © Amy Rogers © Carl Corbidge

11. This study focuses on the Devil’s Punch Bowl SSSI which is located near Hindhead in Surrey. Guildford Hindhead

12. The Devil’s Punch Bowl is a large (280 ha) SSSI in Surrey. Devils Punch Bowl SSSI also forms part of the following larger sites: Wealden Heaths Phase II Special Protection Area. Surrey Hills Area of Outstanding Natural Beauty. Compare and contrast the different designations held by the Devil’s Punch Bowl (i.e., SSSI, Special Protection Area, Area of Outstanding National Beauty). Answer question 1 on page 2 of your workbook. About the Devil’s Punch Bowl

13. Supports a series of semi-natural habitats. Units 1, 2 and 4 are dominated by lowland heathland. Units 3 and 5 are dominated by mixed deciduous and yew woodland. Other habitats present include scrub and meadows. 1 2 3 4 5 Supports over 60 breeding bird species – heathland species include nightjar, stonechat, tree pipit and whitethroat. Provides habitat for a rich and varied invertebrate fauna. About the Devil’s Punch Bowl

14. Section B The effect of anthropogenic nitrogen deposition on heathland © Amy Rogers © Carl Corbidge

15. The A3 is a very busy road, with an annual daily average traffic flow of over 20,000 vehicles. These vehicles will be emitting fumes containing nitrous oxide. Nitrous oxide could be deposited on the heathland at the Devil’s Punch Bowl, adding nutrients to the soil. Nitrogen deposition, the A3 and heathland

16. You have been asked to conduct a survey to help understand how pollution from the traffic using the A3 is affecting the heathland vegetation. We would like to know whether nitrogen deposition from the exhaust fumes is affecting the heathland vegetation composition (i.e. which species are growing and how dominant they are). You will collect data on the percentage cover of the following species groups: Dwarf Shrubs (heather and gorse) Bracken Grasses Mosses Lichens Nitrogen deposition, the A3 and heathland

17. Identification training: dwarf shrubs Dwarf Shrub 1 - Heather Cross-leaved heath (Erica tetralix) Common heather (Calluna vulgaris) Bell Heather (Erica cinerea) © Roger Key © Peter Crittenden There are three species of heather that may be found on our field sites. You do not need to be able to distinguish between these species.

18. For the purposes of this study, we do not need to distinguish between the different species of heather. All three species have the following characteristics: Small purple or pink flowers Small, narrow, linear green leaves. Cross-leaved heath (Erica tetralix) Identification training: Heather © David Glynne Fox

19. Identification training: dwarf shrubs Dwarf Shrub 2 - Gorse © Roger Key Yellow flowers. Stems have long spines.

20. Identification training: moss Small, simple leaves. Grow close to ground. No flowers. May appear brown in colour if conditions have been dry. © Roger Key

21. Identification training: lichen Occur in range of shapes and colours. Made of a fungus and an alga. © Lauren Gough

22. Practice time! Warning: Not all plants will have flowers! Can you identify the different types of plant in this quadrat? Dwarf Shrub (gorse) Dwarf Shrub (heather) Moss Lichen

23. The two main things we need to think about are: What kind of things might we need to plan/think about before starting an investigation such as this one? Nitrogen deposition, the A3 and heathland But before we begin….. How will we measure percentage cover? What is our sampling unit? How should our sampling units be arranged? You will be collecting data on the percentage cover of different plant species to assess the impact of anthropogenic nitrogen pollution on heathland plant communities

24. Place the quadrat over the area of vegetation to be surveyed. Look at the quadrat from directly above. The total area of ground within the quadrat is 100%. For each plant species, estimate the % area of the quadrat that it covers. How will we measure plant percentage cover? © Peter Crittenden We will be using quadrats (0.5 x 0.5 m) to measure the percentage cover of heather and bracken:

25. Estimate the percentage cover of heather in this quadrat. Did everyone in your class give the same answer? How varied were the estimates of percentage cover? Using quadrats to measure % plant cover © Peter Crittenden

26. Should we include plants which are rooted outside the quadrat, but whose leaves fall over the quadrat? Using quadrats to measure percentage plant cover © Peter Crittenden Should we count grass or plants that appear to be dead?

27. How should we arrange our quadrats? For your investigation you will compare samples (quadrats) of vegetation taken in areas close to the A3 with samples (quadrats) of vegetation taken in areas far away from the A3. The samples (quadrats) that are far away from the A3 need to be separated from the A3 by a large enough distance to not be affected by the traffic emissions. Using the graph provided on page 4 of your workbook, calculate the distance at which emissions from the A3 should no longer affect the heathland vegetation on the Devil’s Punch Bowl SSSI.

28. The following slide shows two alternative sampling strategies that could be used to investigate whether emissions from the traffic using the A3 is affecting the heathland vegetation. Which of the sampling strategies do you think is better and why? How should we arrange our quadrats?

29. A3 Distance beyond which emissions have minimal impact on heathland vegetation Sampling strategy A (systematic)Sampling strategy B (random) = quadrat

30. A3 Alternative sampling strategy (systematic) Can you think of any alternative sampling strategies that would be appropriate? In the sampling strategy shown on the right, why is it important to have more than one transect?

31. Within each site, how many quadrats of data should we collect? Should we collect, 1, 5, 10 or more? The more the better! More quadrats mean more information about the effect of nitrogen deposition on the percentage cover of heather and bracken. In practice, the number of quadrats you collect will depend on factors such as the size of the study site and the amount of time you have for data collection. How many quadrats of data should we collect? In this study you will be collecting 5 quadrats per site.

32. Complete questions B2 to B4. Open the document ‘quadrats.ppt’ to start collecting your data!

33. Were there any anomalous results? Questioning the experimental methodology Nitrogen deposition, the A3 and heathland What were the potential sources of error in your investigation, and how may they have affected the validity and reliability of your data? What were the limitations of your methodology and the site selection? How may these limitations have affected your ability to assess whether nitrogen deposition affects the heathland plant species community.

34. Potential sources of error could include: Percentage cover is a subjective measure – could affect reliability of heather and bracken abundance measures. ‘Boundary decisions’ – when individuals overlap the edge of the quadrat do you include them or not? How might the time of year affect the percentage cover of different species? Return to project evaluation slide Questioning the experimental methodology Nitrogen deposition, the A3 and heathland

35. Limitations of the study include: Five quadrats per site is a relatively small sample size. We have not collected our own data on nitrogen deposition – are working on the assumption that the A3 does cause nitrogen pollution. Could anything else explain the effect we observed? Using photographs of quadrats we cannot seen beneath the leaves of tall plants (e.g., bracken) Return to project evaluation slide Questioning the experimental methodology Nitrogen deposition, the A3 and heathland

36. Section C The effect of habitat fragmentation on heathland © Amy Rogers © Carl Corbidge

37. The A3 currently passes through the Devil’s Punch Bowl SSSI. A3 The A3 road The A3 prevents the Devil’s Punch Bowl heathland from being a continuous habitat. Instead it forms two discrete habitat blocks, one north and one south of the A3. The process of breaking a previously continuous habitat into smaller, un-linked sections is called habitat fragmentation.

38. The effect of habitat fragmentation Interior habitat Edge habitat Answer question C1 in your workbook

39. Fragmentation increases the amount of edge habitat. This can cause what is known as the ‘edge effect’ – when the edge of a habitat experiences different conditions (abiotic or biotic) to the interior of the habitat. The effect of habitat fragmentation – Edge Effects Interior habitat Edge habitat

40. Edge Effects For example, imagine a forest surrounded by arable fields. The areas around the edge of the forest will experience higher light levels than the areas in the interior of the forest. Interior habitat Edge habitat Arable field If a road is built through the middle of the forest, the areas of forest bordering the road will also experience higher light levels. The amount of edge habitat, and the edge effect, has increased.

41. The effect of habitat fragmentation – Edge Effects Answer questions C2 – C3 in your workbook The smaller a habitat is, the greater the proportion of its area which experiences edge effects. Edge effects can dramatically alter the plant and animal communities found on the edge of habitats.

42. Entrance to the1.8 km tunnel underneath the Devil’s Punch Bowl SSSI. Image source: www.nce.co.uk The A3 that currently runs through the Devil’s Punch Bowl is being improved. The A3 Improvement Scheme Following the improvements, traffic will flow underneath the site in a tunnel instead of crossing the site overland.

43. Image produced at www.magic.gov.uk on 02/03/2011www.magic.gov.uk Old route of A3 New route of A3 A3 Tunnel

44. What benefits might the A3 Improvement Scheme have on the flora and fauna of the Devil’s Punch Bowl heathland? The A3 Improvement Scheme

45. Potential benefits of the A3 Improvement Scheme include: Reduced nutrient enrichment of the soil from emissions of nitrous oxides (NOx). This will reduce the likelihood of nitrogen-loving species (e.g., scrub, bracken, trees) invading and outcompeting typical heathland plant species. Other benefits include: Reduced loss of individuals due to road kill; Reducing effects of habitat fragmentation allowing species (particularly reptiles) to migrate between the northern and southern portions of the reserve. © Tracey Farrer © Roger Key © David Glynne Fox