Amy Rogers Carl Corbidge Heathlands and Roads Virtual

• You are going to be learning about a very important habitat – lowland heathland. • You will learn about a case study of the A 3 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. © Amy Rogers What are you going to do?

Objectives 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.

What is nitrogen deposition? Atmosphere • 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. Biosphere

Naturally occurring nitrogen gas (N 2) only enters the biosphere after being fixed by micro-organisms or lightning. Nitrogen-containing compounds such as nitrous oxides (NOx) 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. N 2 NH 3 & NOX

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.

Nitrogen deposition: Nitrous Oxide (NOx) ? Which of these sources was the greatest emitter of nitrous oxide (NOx) in England Wales in 2005? Industry 10% Domestic & Commercial 21% Road Transport 51% Other Sources 18% Source: Data for Neighbourhoods and Regeneration (http: //www. data 4 nr. net/resources/503/)

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

The aim of our investigation • We will be investigating both the impact of anthropogenic nitrogen pollution from traffic emissions, and the impact of habitat fragmentation. © Lauren Gough • The main aim of our investigation is to understand the impact roads such as the A 3 can have on heathland habitats.

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

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

About the Devil’s Punch Bowl 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 5 Supports a series of semi-natural habitats. 4 • 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. Supports over 60 breeding bird species – heathland species include nightjar, stonechat, tree pipit and whitethroat. Provides habitat for a rich and varied invertebrate fauna. 3 1 2

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

Nitrogen deposition, the A 3 and heathland • The A 3 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 A 3 and heathland You have been asked to conduct a survey to help understand how pollution from the traffic using the A 3 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

Identification training: dwarf shrubs Common heather (Calluna vulgaris) Bell Heather (Erica cinerea) © Roger Key © Peter Crittenden Dwarf Shrub 1 - Heather 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. Cross-leaved heath (Erica tetralix)

© David Glynne Fox Identification training: Heather 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: dwarf shrubs © Roger Key Dwarf Shrub 2 - Gorse • Yellow flowers. • Stems have long spines.

© Roger Key Identification training: moss • Small, simple leaves. • Grow close to

© Lauren Gough Identification training: lichen • Occur in range of shapes and colours.

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

Nitrogen deposition, the A 3 and heathland 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 But before we begin…. . ? What kind of things might we need to plan/think about before starting an investigation such as this one? The two main things we need to think about are: • How will we measure percentage cover? What is our sampling unit? • How should our sampling units be arranged?

© Peter Crittenden How will we measure plant percentage cover? We will be using quadrats (0. 5 x 0. 5 m) to measure the percentage cover of heather and bracken: • 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.

© Peter Crittenden Using quadrats to measure % plant cover ? 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?

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

How should we arrange our quadrats? For your investigation you will compare samples (quadrats) of vegetation taken in areas close to the A 3 with samples (quadrats) of vegetation taken in areas far away from the A 3. The samples (quadrats) that are far away from the A 3 need to be separated from the A 3 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 A 3 should no longer affect the heathland vegetation on the Devil’s Punch Bowl SSSI.

How should we arrange our quadrats? The following slide shows two alternative sampling strategies that could be used to investigate whether emissions from the traffic using the A 3 is affecting the heathland vegetation. ? Which of the sampling strategies do you think is better and why?

Distance beyond which emissions have minimal impact on heathland vegetation Sampling strategy A (systematic) A 3 = quadrat Sampling strategy B (random)

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? A 3 = quadrat

How many quadrats of data should we collect? ? 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. In this study you will be collecting 5 quadrats per site.

Open the document ‘quadrats. ppt’ to start collecting your data! Complete questions B 2 to B 4.

Nitrogen deposition, the A 3 and heathland Questioning the experimental methodology Were there any anomalous results? 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.

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

The A 3 road The A 3 currently passes through the Devil’s Punch Bowl SSSI. The A 3 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 A 3. The process of breaking a previously continuous habitat into smaller, un-linked sections is called habitat fragmentation. A 3

The effect of habitat fragmentation Edge habitat Interior habitat Answer question C 1 in your workbook

The effect of habitat fragmentation – Edge Effects • 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. Edge habitat Interior habitat

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. • 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. Arable field Edge habitat Interior habitat

The effect of habitat fragmentation – Edge Effects • Edge effects can dramatically alter the plant and animal communities found on the edge of habitats. • The smaller a habitat is, the greater the proportion of its area which experiences edge effects. Answer questions C 2 – C 3 in your workbook

The A 3 Improvement Scheme The A 3 that currently runs through the Devil’s Punch Bowl is being improved. Following the improvements, traffic will flow underneath the site in a tunnel instead of crossing the site overland. Entrance to the 1. 8 km tunnel underneath the Devil’s Punch Bowl SSSI. Image source: www. nce. co. uk

A 3 Old route of A 3 New route of A 3 Tunnel Image produced at www. magic. gov. uk on 02/03/2011

The A 3 Improvement Scheme ? What benefits might the A 3 Improvement Scheme have on the flora and fauna of the Devil’s Punch Bowl heathland?

© David Glynne Fox • 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. © Roger Key Potential benefits of the A 3 Improvement Scheme 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 Other benefits include: