Recreating species rich grasslands

using the hemiparasitic plant

Rhinanthus minor

Name: Harriet Cuthbert

Project supervisors: Tracey Hamston and Dave Ellacott

Whitley Wildlife Conservation Trust

The University of York

2007- 2008

Contents

Abstract i

1 Introduction 1 1.1 Grassland classification and mesotrophic grasslands 1 1.2 Intensification 1 1.3 Grassland management techniques 2 1.4 Grassland restoration techniques 3 1.5 Rhinanthus minor L 4 1.6 The use of seed in meadow restoration 7 1.7 Aims 7 1.8 Hypothesis 8

2 Study area, materials and methods 9 2.1 Study area 9 2.2 Materials 10 2.3 Methods 11

3 Results – site one 15 3.1 Biodiversity 15 3.2 R. minor 16 3.3 Grass productivity 17 3.4 Wildflower establishment 19

4 Results – site two 21

4.1 R. minor 21 4.2 Wildflower establishment 21

5 Discussion 23 5.1 Site one 23 5.2 Site two 25 5.3 Limitations and management 26 5.4 Future management 27

6 References 28

7 Acknowledgements 34

8 Appendix 35

i

Abstract

Since 1930, unimproved lowland grassland has suffered great losses throughout

England and Wales because of farming intensification and high levels of artificial

fertiliser application. The rise in nutrient supply has allowed nutrient-demanding

coarse grass species to thrive and has led to an overall decline in plant species

diversity which, in turn, has directly affected the faunal assemblages supported. It has

been suggested that Rhinanthus minor, a hemiparasitic annual plant, can be used to

restore such grasslands by parasitising and reducing the vigour of the dominant grass

species allowing the less competitive species to colonise.

Primley meadow, South Devon, is a south facing, mesotrophic area of grassland with

low biological diversity. In August 2005, 60 permanent quadrats were established and

various treatments applied in a randomised block design (site one). These included all

combinations of two ground preparation methods (short cut and rotovation) and three

sowing regimes (R. minor only, a wildflower mix only and both). Results from site

one indicate that R. minor significantly reduced grass height and biomass but as yet

has had no overall effect on biodiversity, although sown wildflower species had

increased in abundance. In October 2007, a larger field trial of R. minor was

established (site two). A plot (90 m x 90 m) was created using the most successful

treatment from the previous two years i.e. the vegetation was short cut and both R.

minor and wildflower mix were sown together. Results from site two show some of

the wildflowers sown to have established; however, R. minor appears not to have

germinated.

Keywords: Rhinanthus minor; restoration; mesotrophic; biodiversity

1

Recreating species rich grasslands using the hemiparasitic plant

Rhinanthus minor

1. Introduction

1.1 Grassland classification

Habitat conversion from natural or semi-natural vegetation to intensive agriculture is

at the heart of the present biological diversity crisis (Walker, 2004). In 1992,

environmental targets for 2010 were set up at the convention on biological diversity

for all the countries involved (CEH1, 2007). In the United Kingdom, lowland

grassland was highlighted as a particular habitat in need of assistance (JNCC, 2006).

Action plan objectives for the UK include halting depletion of lowland meadow and

attempting to re-establish 500 ha of lowland meadow of wildlife value (BAP, 2008).

Rodwell (1998) has developed a comprehensive classification system, the National

Vegetation Classification (NVC), to recognise and describe plant communities in

Britain. Thus, grassland in the UK has been categorised into 14 calcareous

communities, 21 acid communities and 13 mesotrophic communities (e.g. MG1-13).

Mesotrophic grasslands consist of sites of neutral soil pH, but due to farming

intensification have experienced insufficient grazing and application of high levels of

fertiliser. This has resulted in great losses of grassland with significant biodiversity

value. Mentioned below in 1.2.

1.2 Intensification

Between 1930 and 1984, unimproved lowland grassland in England and Wales was

reduced by 97 % (Fuller, 1987). This is a result of increasing agricultural efficiency,

where a high proportion of lowland grassland in the UK has been subjected to

artificial fertiliser application (Jefferson, 2005) and farming intensification. Berendse

et al. (1997) has shown a rise in nutrient supply leads to a decline in species diversity.

This is because high nutrient supplies generate a much more limited grassland species

list where a few nutrient demanding species that thrive in productive, human altered

environments (Walker, 2004) dominate the area and out compete softer grasses and

dicots abbr., in particular, because of their high seed production (Bullock et al., 1994).

2

Plant species most vulnerable with the decline of lowland grassland include greater

butterfly orchid Platanthera chlorantha and wood bitter vetch Vicia orobus (BAP,

2008). The decrease in wildflowers and overall species diversity of grassland directly

impacts the faunal assemblages it supports (Pywell et al., 2004; Vickery et al., 2001).

Lowland meadows are important habitats for farmland birds; the curlew Numenius

arquata, in particular, has experienced a major range contraction and was highlighted

by the Biodiversity Action Plan (BAP) as a UK priority species (BAP, 2008). In

Devon there are only 30 breeding pairs remaining as agricultural improvement has

resulted in a loss and fragmentation of breeding sites for this species (Devon BAP,

2008).

Although the majority of land in the UK is grassland, most mesotrophic grasslands are

less than 10 ha in size (Jefferson and Robertson, 1996) and the total extent of

unimproved mesotrophic grassland in England and Wales is between 7500 ha and

15000 ha (Blackstock et al., 1999). This results in these grassland areas being small,

fragmented and highly localised (BAP, 2008). Therefore, it is necessary to protect and

expand existing lowland grassland habitats and reverse recent successional traits

(Blackstock et al., 1999).

1.3 Grassland management techniques

1.3.1 Grazing

Many areas of lowland grassland have been destroyed by not only ploughing and

excessive fertilisation, but also by the lack of management and abandonment such as

hilly areas where agricultural equipment cannot reach (Jongepierová et al., 2007).

Grazing of livestock, which involves defoliation, treading and manuring (Morris,

2000; Gilbert and Anderson, 1998), is an efficient management technique for

maintaining grasslands (Marriott et al., 2003). Livestock remove new sward growth

continually which restricts the dominant coarse grasses by altering the relative

abundance and competitive ability of different plant species (Vickery et al., 2001).

The trampling effect of stock is also beneficial, creating bare ground and damaging

competitive species (Crofts and Jefferson, 1999). The disturbance caused by grazing

opens up the sward and creates germination gaps; forb seed from hay crop or sown

3

seed are consequently able to colonise the area (Walker, 2004). Grazing increases the

abundance of dicots, in particular, because of their high seed production (Bullock et

al., 1994). Grazing is selective, which therefore results in a more diverse range of

invertebrates surviving intensive grazing than other sward management techniques

(Vickery et al., 2001). The advantage of seasonal grazing over continuous grazing is

the promotion of sward heterogeneity and hence increased invertebrate diversity

(Vickery et al., 2001).

1.3.2 Cutting

In contrast to grazing, cutting is a far more aggressive and controlled management

technique (Morris, 2000) where the sward is non-discriminately cut to a uniform

height (Rodwell, 1998). This technique is considered detrimental to invertebrate

populations (Vickery et al., 2001; Morris, 2000). Therefore, timing of the cut is

critical (Morris, 2000; Baines, 1998). Cutting the grassland in autumn, both reduces

the impact on invertebrates, but also on wildflower populations, enabling seed to set

first and persist for longer in the seed bank (Smith and Jones, 1991). Removal of cut

material avoids the development of thick thatch which suppresses and smothers the

weaker, smaller plants (Gilbert and Anderson, 1998); it can also function as a method

to reduce soil fertility (Schaffers et al., 1998; Walker 2004) as well as optimise

conditions for the colonisation and establishment of target species.

Hayes and Sackville (2001) stated cutting favours coarse grasses whereas grazing

alone encourages the establishment of undesirable weed species. However, cutting

with aftermath grazing has generally been more successful than either cutting or

grazing alone (Walker, 2004), suggesting this is the best management technique.

1.4 Grassland restoration techniques

1.4.1 Direct methods

Restoration of grassland to reduce the negative effects of high soil fertility from the

application of fertiliser can be achieved in a number of ways. The two direct methods

commonly used are 1) the removal of top soil and 2) cropping. As cutting and grazing

do not always reach set targets quickly, top soil removal can accelerate the grassland

4

restoration process. This technique eliminates nutrients from the top layers of soil but

also removes both desirable and undesirable species from the seed bank (Westbury

and Dunnett, 2000). Berendse et al. (1992) showed that removing top soil caused a

sharp fall in productivity which had a positive effect on species diversity. However,

the process is costly and is therefore only worth stripping if the nutrient levels in the

lower horizons of the soil are significantly less than those of the surface (Gilbert and

Anderson, 1998; Bullock and Pywell, 2005). To reduce the price of this technique,

top soil may be re-allocated when sold to recover part of the cost (Gilbert and

Anderson, 1998). Reducing soil nutrients can also be achieved by continuous

cropping. This technique involves cutting of the sward at the end of the growing

season and removing arisings.

1.4.2 Indirect methods

Two indirect methods can also be used to resolve the problems associated with

farming intensification. These are 1) rotovation to scarify the land and 2) the use of

parasitic plants. Rotovation essentially mimics the effects of intensive grazing by

turning the top layer of the soil containing the seed bank. Rotovation, however,

disturbs the soil to a greater depth than grazing. This creates germination gaps for less

competitive species and wildflower seeds that are sown. Furthermore, establishment

of seeds can be enhanced through the disturbance as shown by Westbury et al.

(2006). The introduction of hemi parasitic angiosperms of the genus Rhinanthus has

shown to inhibit the growth of dominant grass species (Davies et al., 1997; Joshi et

al., 2000). Subsequently, hemiparasites have been used in grassland restoration

projects to promote growth of desirable wildflower species that would have

previously been out competed.

1.5 Rhinanthus minor L.

Rhinanthus minor minor (herein referred as R. minor) (figure 1) is one of six

subspecies of Rhinanthus minor recognised in the British Isles and is widespread

throughout most of Europe (Westbury, 2004). R. minor, commonly known as yellow

rattle, is a late summer annual capable of facultative root hemiparasitic growth

(Westbury, 2004; Westbury & Davies, 2005). It is defined as a hemiparasite because

of the presence of chlorophyll (Musselman and Press, 1995), enabling both

5

autotrophic and heterotrophic growth (Joshi et al., 2000; Westbury, 2004). Nutrients

and water are obtained via the vascular system using a structure known as the

haustorium; this is a physiological and morphological bridge that forms between the

host and the parasite (Riopel and Timko, 1995). R. minor sets seed between June and

August (Bullock et al.) resulting in an autumn cut being beneficial by both allowing

the seed to set and assist seed dispersal (Bullock et al., 2003). During the winter, the

seed in the soil surface layers are chilled which results in the breaking of dormancy

for the subsequent spring germination (Smith et al., 2000). Unlike most annuals, it

has no persistent seed bank (Gilbert and Anderson, 1998; Westbury and Davies,

2005) so the population size is dependant on the production and dispersal of the seed

each year (Coulson et al., 2001).

Figure 1. R. minor in flower.

R. minor has been proposed as a management tool for use in restorative grassland

practices to increase botanical diversity (Davies et al., 1997; Pywell et al., 2004;

Bargett et al., 2006; Jefferson, 2005; Westbury et al., 2006) and is most abundantly

found in grassland habitats (Keith et al., 2004). Current grassland restoration methods

to reduce soil fertility and vigour of competitive plants are often unsuccessful or

disruptive and expensive (CEH2, 2007), whereas R. minor establishment can be

achieved relatively easily and cheaply (Bullock and Pywell, 2005). It has been shown

that, like most parasites, R. minor has a broad host range and can parasitise

approximately 50 host species from 18 different families within European grasslands

6

(Westbury, 2004). A single R. minor plant has even been found to parasitise up to

seven different host species simultaneously (Westbury, 2004). However, R. minor is

not a true generalist and has shown host preference (Press and Phoenix, 2005) which

will alter the competitive balance within a community, increasing the competitive

status of non-host species (Joshi et al., 2000; Bardgett et al., 2006). R. minor has

demonstrated considerable host selectivity with preferred hosts being from the

legume family (Gibson and Watkinson 1989). It has been suggested that the most

likely reason for this is special nutrient requirements that can only be supplied by

particular hosts (Gibson and Watkinson, 1989). Rumer et al. (2007) showed that roots

of potential hosts respond differently when R. minor attempts to form haustoria with

them. Fabaceae roots showed a weak connection, where a slight lignification

occurred, and no reaction was observed between the endophyte and cortical tissue of

the host root. In contrast, grass roots react with strong lignification of all cells within

the stele, thus resulting in the potential to serve as a good host (Rumer et al., 2007).

However, Davies et al. (1997) indicates that host choice is non-discriminatory and the

most dominant species tends to be suppressed. Species poor grasslands exhibit high

levels of soil nutrients which lead to a few aggressive grass species then dominating

the area by out competing other species. It has been theorised that R. minor will

parasitise these dominant species (Pywell et al., 2004) reducing both sward height

and vigour, allowing the less competitive species to colonise, which in turn will create

a more diverse grassland. Another added benefit of R. minor is the yearly death of the

annual that will leave colonisation gaps, and therefore, open up the sward (Joshi et

al., 2000). Although there are many benefits of using R. minor to increase

biodiversity in grassland, it has been suggested that the parasite is too unpredictable,

mainly due to variability in composition and differences in productivity, to be an

effective restoration tool (Westbury and Davies, 2005). Evidence also suggests that

R. minor could potentially be harmful to livestock; however, prolonged periods of

exclusive consumption are required for toxicity (Westbury and Davies, 2005).

Nevertheless, despite the potential problems, the parasitic nature of R. minor makes it

a suitable agent for restorative grassland management.

To assess how successful the introduction of R. minor into grassland is, a variety of

methods can be undertaken. These include 1) measuring biomass; 2) measuring sward

7

height throughout the growing season; 3) measuring species richness before and after

introducing R. minor. Biomass of an area of grassland gives an indication of

productivity; coarse grasses will have a high biomass in nutrient rich soils.

Introduction of R. minor in North Yorkshire led to a reduction in biomass that ranged

from 8-73 % within sites, with a noticeable decline in grasses coinciding with an

increase in the proportion of dicotledons (Davies et al., 1997). Bardgett et al. (2006)

also showed that total above-ground biomass reduced significantly over three years,

when R. minor was present. A strong, inverse relationship between the frequency of

R. minor and sward height was shown; there was also evidence of a threshold

frequency of the hemiparasite above which there was a significant reduction in

grassland productivity (Pywell et al., 2004).

1.6 The use of seed in meadow restoration

In the UK, the favoured method for re-creating species-rich grasslands on ex-arable

soils has been direct seeding with mixtures of suitable species (Walker, 2004; Coulson

et al., 2001) as not all seeds can arrive naturally, largely because of habitat

fragmentation and a poor seed bank. The origin of seed also needs to be considered

and choice of seed is dependant on individual species requirements such as soil pH

preference, bio-geographical region and tolerance to intended management practices.

Seeds used in meadow restoration must be of British native origin, but locally

collected seed is more desirable as to maintain local genetic adaptation. To ensure

establishment of meadows with a typical regional character and to avoid introduction

of non-native species and genotypes, it is necessary to select seeds of appropriate

provenance (Jongepierová et al., 2007).

1.7 Aims

The aims of this project are to increase biological diversity at Primley meadow from

the introduction of the hemiparasite R. minor by:

• Monitoring plots, in site one, with and without the introduction of R. minor

and sown wildflower mix and comparing the ground preparation techniques:

short cut and rotovation, to find the best treatment.

• Using data collected from previous years to apply correct management and

restoration techniques to a large scale plot in site two.

8

1.8 Hypothesis

R. minor will reduce coarse grass creating a more favourable habitat for other species

to grow, resulting in an increase in biodiversity.

9

2. Study area, materials and methods

2.1 Study area

2.1.1 Site

Primley meadow is a south facing, mesotrophic meadow located in South Devon (OS

grid reference SX 880601). It is an isolated site, surrounded by woodland and

residential areas, resulting in the source of wildflower to be limited to the seed bank.

The meadow was previously used as horse pasture, the outcome being highly

fertilised soil, dominated by a few coarse grasses resulting in low biological diversity.

Primley meadow is owned by the Whitley Wildlife Conservation Trust (WWCT) and

is an important wildlife habitat. The area is open to the public and frequently visited

by dog walkers. In 1995, fertiliser application stopped and since then, an autumn cut

has taken place and arisings removed to reduce soil nutrients and increase

biodiversity. The meadow is split into seven sections and each year a different area,

determined by a set rota, is not cut which acts as a refuge to invertebrates. The

meadow is dominated by a few coarse-leaved tussock grass species such as

Arrhenatherum elatius, Dactylis glomerata and Holcus lanatus. Two areas of the

meadow chosen for this study are named site one and site two (figure 2). Site one is a

sloped area of grassland near the top of the meadow, whilst site two is an area of

coarser grass which is situated in a slightly more shaded part of the meadow.

10

Figure 2. An aerial view of Primley Park including the woodland (pale yellow) and meadow (pale green). Positions of site one and two are shown in dark green.

2.1.2 NVC community

The NVC provides a suitable framework to recognise and describe the plant

community to classify an area of grassland. In 2005, ten randomly placed quadrats

(2 m x 2 m, subdivided into 100 squares) were placed around site one to determine the

community type before treatments were applied. The results show that vegetation

closely matched that of a MG1c community Arrhenatherum elatius (57.14 %

similarity. This type of grassland is common of road side verges and un-improved

lowland meadows (Rodwell, 1998). In September 2007, ten randomly placed 2 m x

2 m quadrats were placed in site two. All plant species within the quadrats were

identified and rooted percentage cover was determined. Data was inputted into

MAVIS Plot Analyser (v1.0) (Smart, 2000) which concluded that site two, like site

one, also matched a MG1c community Arrhenatherum elatius (54.79 % similarity).

2.2. Materials

2.2.1 Seed selection

To increase floristic diversity a wildflower mix was applied to both site one and two

because the area is isolated so seed cannot arrive through natural causes. A selection

11

of five wildflower species were chosen, using the floristic table for a MG1c

community (Rodwell, 1998), which suited the community already present at Primley

meadow. Species were also selected for their aesthetic value and germination rates.

The wildflower mix included Achillea millefolium, Centaurea nigra, Leucanthemum

vulgare, Prunella vulgaris and Knautia arvensis. R. minor was chosen because of its

hemiparastic growth and compatibility with grassland areas, in particular hay

meadows.

2.3 Methods

2.3.1 Experimental design – site one

In 2005, 60 2 m x 2 m permanent quadrats were set up in site one using metal discs to

allow identification of the plots again using a metal detector and arranged according

to figure 3. Each of the quadrats had a 2 m guard row to reduce contamination of

R. minor and wildflower mix between plots. Twelve different treatments, as shown in

the treatment key (figure 3), each with five replicates were arranged in blocks. The

treatments were arranged in a randomised block design. The two ground preparation

techniques include 1) Short cut; 2) Rotovation; which were both applied in October

2005 and 2006. These were chosen because both were feasible management

techniques for Primley meadow and unlike top soil removal, were inexpensive.

Grazing is not possible because the area is open for public access. Six different seed

treatments were applied in October 2005 and 2006. These include 1) Control; 2)

Wildflower seed mix sown 2005; 3) Wildflower seed mix sown 2006; 4) R. minor

sown 2005; 5) R. minor and wildflower mix sown 2005; 6) R. minor sown 2005 and

wildflower mix sown 2006. Both R. minor and wildflower mix were sown at a rate of

1g/1m2 (Landlife, 2007).

2.3.2 Full vegetation survey

A full vegetation survey took place at both site one and site two. Site one was

surveyed in April, June and August 2008. Site two was surveyed every month from

April to August 2008 because it was a newly prepared plot. This included wildflower

identification to enable rooted percentage cover of each species to be calculated

within each 2 m x 2 m quadrat. Each of the grass species had rooted percentage cover

12

estimated by eye. Bare ground cover was calculated for each quadrat to see how fast

colonisation occurred in the vegetation gaps. To measure grass height, the drop disc

technique (disc 60 g, 240 mm x 264 mm) was used. The disc was thrown randomly

onto the quadrat and a measuring pole was pushed through a hole in the centre to give

a reading of grass height. This allowed grass productivity to be assessed as the

growing season of R. minor developed, enabling measurement of the parasite’s

effectiveness.

2.3.3 Preliminary study

In 2003, a pilot study of Primley meadow was carried out by Gillepsie (2004). This

study analysed the seed bank and concluded that it was limited which therefore, could

be a potential restrictive factor for the restoration of this meadow. This project is a

longitudinal study first started in August 2005. Site one had a full vegetation survey

carried out for each of the 60 quadrats which was conducted in August 2005 (before

treatments had been applied to give baseline data) and February through to August

2006 every month by Cunningham (2006). This survey was continued by Chavner

(2007) from March to August 2007.

2.3.4 Experimental design – site two

In 2007, using data collection from the previous two years, a larger plot (90 m2 (15 m

x 6 m)) in another area of grassland at Primley Meadow (site two) was set up. Data

prior to September 2007 from site one concluded that the treatment YW5 SC

(R. minor and wildflower mix sown in the same year with the short cut ground

preparation) was most successful. The larger plot was marked out using metal discs at

each of the four corners, short cut and raked until bare ground was visible. Both

R. minor and wildflower mix (Achillea millefolium, Centaurea nigra, Leucanthemum

vulgare, Prunella vulgaris and Knautia arvensis) were sown at an increased density of

1.5 g/m2 to raise the colonisation rates shown at site one over the previous two years.

The seed mix was combined with sawdust and scattered manually. This site had

random 2 m x 2 m quadrats throughout the area rather than the permanent quadrats as

to fully assess the whole area.

13

2.3.5 Biomass

Due to time limits, it was impractical to clip all vegetation within the entire quadrat as

would be desired. In September 2007, productivity was assessed by clipping a random

20 cm2 area to soil level using hand shears within each 2 m2 quadrat at site one. Grass

was separated out from all other vegetation, dried at 80 oC and weighed.

2.3.6 Data analyses

Biodiversity was calculated using the Simpson’s Index of Diversity (appendix). This

was chosen as it represented both species richness and evenness. It ranges from zero

to one, with zero being no diversity and one being infinite diversity. Levene’s test for

the homogeneity of variances was used to determine validity of the univariate

ANOVA and independent samples t-test. To analyse data over the years, repeated

measures ANOVA was carried out because each quadrat was surveyed three or more

times. Mauchly’s test of sphericity was used to test the variances of the differences

between conditions was equal. When a significant sphercity result was produced the

Greenhouse-Geisser correction was used. All data analysis was carried out using

SPSS 15.0.

14

Figure 3. Arrangement of plots (2 m2 quadrat with 2 m guard row) within Primley Meadow at site one. Each colour represents a different replicate block

Code Treatment C SC Short cut and control C R Rotovation and control W5 SC Short cut and wildflower seed mix sown in September 2005 W5 R Rotovation and wildflower seed mix sown in September 2005 W6 SC Short cut and wildflower seed mix sown in September 2006 W6 R Rotovation and wildflower seed mix sown in September 2006 Y5 SC Short cut and R. minor sown in September 2005 Y5 R Rotovation and R. minor sown in September 2005 YW5 SC Short cut and R. minor and wildflower seed mix sown in September 2005 YW5 R Rotovation and R. minor and wildflower seed mix sown in September 2005 YW6 SC Short cut and R. minor sown in 2005. Wildflower seed mix sown in September 2006 YW6 R Rotovation and R. minor sown in 2005. Wildflower seed mix sown in September 2006

Q Treatment Q Treatment Q Treatment Q Treatment 1 Y5 SC 16 YW5 R 31 W5 SC 46 Y5 R 2 C SC 17 C R 32 W5 R 47 W5 SC 3 Y5 R 18 YW6 R 33 YW6 R 48 C R 4 YW6 R 19 YW5 SC 34 YW5 R 49 C R 5 W6 R 20 W6 SC 35 C R 50 Y5 R 6 W6 SC 21 Y5 SC 36 W6 SC 51 YW6 SC 7 YW5 SC 22 W6 R 37 YW6 SC 52 W5 R 8 YW6 SC 23 YW6 SC 38 W6 SC 53 W6 SC 9 C R 24 Y5 R 39 Y5 SC 54 YW5 SC 10 YW5 R 25 Y5 R 40 YW5 SC 55 Y5 SC 11 W5 R 26 Y5 SC 41 C SC 56 C SC 12 W5 SC 27 W6 R 42 YW5 R 57 W5 SC 13 W5 R 28 C SC 43 W6 R 58 YW5 R 14 W5 SC 29 YW6 SC 44 YW6 R 59 YW6 R 15 C SC 30 YW5 SC 45 W5 R 60 W6 R

60

59 58

57 56 55

54 53 52

50 49 48

51 47 43

45

42

44

46 40 39

41 36

38 37

35

34

33

24

18

27

32 30

31

23

17

26

22

16

25

29 28

21

15

20

14

19

13

12 11 10

1 6 5 4 3

9 8 7

2

Treatment key

15

3. Results – Site one 3.1 Biodiversity The aim of the project, as a whole, is to increase biodiversity at Primley meadow.

Using Simpson’s Index of Diversity (appendix) biodiversity was calculated using

percentage cover of wildflower species for each quadrat over the three years.

00.10.20.30.40.50.60.70.80.9

1

C SC

C R

W5 S

CW

5 R

W6 S

CW

6 R

Y5 SC

Y5 R

YW5 S

C

YW5 R

YW6 S

C

YW6 R

Treatment

Inde

x of

div

ersi

ty

2005

2006

2007

2008

Figure 4. The mean biodiversity for each treatment across the four years (+S.E). N=5

Figure 4 shows that biodiversity has significantly (F=53.188, p<0.001***) increased

since 2005 (baseline), with the use of ground preparation and seed addition. The

average biodiversity has increased from 0.43 (0.03 S.E) in 2005 to 0.65 (0.02 S.E) in

2008; although biodiversity peaks in 2007 at 0.71 (0.04 S.E). No significant

difference (F=0.537, NS) between treatments was found when analysed using

repeated measures ANOVA. When looking at the values for individual treatments in

August 2008, both controls show the lowest biodiversity (C SC – 0.55 (S.E 0.10); C R

– 0.56 (S.E 0.07)).

16

3.2 R. minor

R. minor has been theorised to reduce grass height and vigour so establishment when

sown was investigated. Data from the June survey each year is presented as this is the

time of year when R. minor is most abundant.

0

10

20

30

40

50

60

2006 2007 2008

Year

Ave

rage

root

ed %

cov

er

Short cut

Rotovation

Figure 5. Mean average rooted percentage cover of R. minor for plots where R. minor was sown and then either short cut or rotovated (+S.E). This data is from the June vegetation survey. N = 15

Figure 5 shows R. minor has successfully established in plots where sown; however,

as shown by the graph, the average rooted percentage cover has significantly

(F=91.108, ***p<0.001 – repeated measures ANOVA) reduced from 2006 to 2008

(42.8 % (3.10 S.E) – 2006 to 17.1 % (4.33 S.E) - 2008). The percentage cover of

R. minor is higher for plots where the ground was short cut rather than rotovated (NS

– Independent samples t-test).

17

0

5

10

15

20

25

30

35

2006 2007 2008Year

Gra

ss h

eig

ht (c

m)

No R.minor

R.minor

Figure 6. The mean grass height (cm) for plots where R. minor was sown and those where no R. minor was sown over the three years in June (+S.E). N = 30

Figure 6 shows grass height was reduced for plots where R. minor had been sown

compared to those where it hadn’t for each of the three years. Using the independent

samples t-test a significant result was found between these treatments for 2006

(T=2.943, *p<0.05) and 2007 (T=3.010, **p<0.005). Repeated measures ANOVA

shows R. minor to significantly reduce grass height (F=27.820, ***p<0.001);

however, ground preparation was non-significant (F=0.019, NS).

3.3 Grass productivity

Grass productivity was measured using the biomass survey in September 2007.

Univariate ANOVA gave a significant result for both R. minor (F=25069.444,

**p<0.005) and ground preparation (F=3640.111, *p<0.05). The average biomass for

plots with R. minor was 12.7 g compared to 14.2 g when R. minor was not applied.

Ground preparation showed rotovation (13.1 g) to reduce biomass by 0.6 g more than

short cut (13.7 g).

** *

18

0

5

10

15

20

25

C SC

C R

W5 S

CW

5 R

W6 S

CW

6 R

Y5 SC

Y5 R

YW5 S

C

YW5 R

YW6 S

C

YW6 R

Treatment

Bio

mas

s (g

)

Figure 7. Mean biomass of grass (+S.E) for each of the different treatments in September 2007. C SC = Control, short cut; C R = Control, rotovation; W5 SC = Wildflower 05, short cut; W5 R = Wildflower 05, rotovation; W6 SC = Wildflower 06, short cut; W6 R = Wildflower 06, rotovation; Y5 SC = R. minor 05, short cut; Y5 R = R. minor 05, rotovation; YW5 SC = R. minor & wildflower 05, short cut; YW5 R = R. minor & wildflower 05, rotovation YW6 SC = R. minor 05, wildflower 06, short cut; YW6 R = R. minor 05, wildflower 05, rotovation. N = 5

The dominance of grasses (table 1) shows how percentage cover and dominance vary

between the five most prevalent species. There is not much change in order

throughout the years, but in 2008, Agrositis stolonifera moves from most abundant to

4th position.

1st 2nd 3rd 4th 5th

2005 A. stolonifera H. lanatus D. glomerata A. elatius A. odoratum

2006 A. stolonifera H. lanatus D. glomerata A. elatius A. odoratum

2007 A. stolonifera H. lanatus A. elatius D. glomerata A. odoratum

2008 H. lanatus D. glomerata A. elatius A. stolonifera A. odoratum

Table 1. The order of dominance of the five most prevalent grasses found at Primley meadow across the years of the study. 1st = most abundant; 5th = least abundant.

19

3.4 Wildflower establishment

August data was used to look at wildflowers as this is when most species were

present. Using all species that were sown in the wildflower mix, total percentage

cover of those which germinated was recorded. Plots were divided into 1) wildflowers

sown in 2005 (same year as R. minor), 2) those sown in 2006 (the following year after

R. minor) and 3) those without wildflower mix applied, and then compared.

Species Total % cover % change from previous year

Achillea millefolium 2005 120

2006 151 26

2007 197 30

2008 187 -5

Centaurea nigra 2005 8 2006 78 875

2007 104 33

2008 271 161

Prunella vulgaris 2005 0

2006 0

2007 6

2008 34 467

Table 2. Total percentage cover of the three most prevalent sown wildflowers Achillea millefolium, Centaurea nigra, Prunella vulgaris for all 60 quadrats across the four years in August.

Table 2 shows the cumulative percentage cover of the three most prevalent sown

wildflower species and the rate they are increasing over the years. Each of the species

has an increasing overall percentage cover from 2005 to 2008, with C. nigra having

increased to the highest density by 2008. Both A. millefolium and C. nigra were

present in the quadrats before the wildflower mix was sown.

20

020406080

100120140160180200

None S

C

None R

2005

SC

2005

R

2006

SC

2006

R

Treatment

Tota

l so

wn

wild

flow

er2005

2006

2007

2008

Figure 8.The total percentage cover of wildflowers (species from wildflower mix) for each different treatment of wildflower application. These include no wildflower sown, wildflower sown in 2005 (same year as R. minor) and wildflower sown in 2006 (the following year after R. minor). SC = Short cut; R = Rotovation. N = 10

Wildflower sown in 2005 with the ground being short cut proved to be the most

successful wildflower application with the highest cumulative percentage cover

(185 % in August 2008). Repeated measures ANOVA showed a significant increase

in wildflowers over the years (F=16.295, p<0.005***). A significant interaction

between year and wildflower application was found (F=3.070, p<0.05*). The post hoc

test (LSD) (table 3) reveals wildflower sown in 2006 is significantly different

(p=0.048*) from that sown in 2005. Wildflower sown in 2005 is almost significantly

different from no wildflower mix application (p=0.077).

Wildflower 1 Wildflower 2 p-value None 2005 0.077

2006 0.827 2005 None 0.077

2006 0.048* 2006 None 0.827

2005 0.048*

Table 3. Post hoc test (LSD) for wildflower application. None = no seed applied; 2005 = wildflower mix sown in 2005; 2006 = wildflower mix sown in 2006.

21

0

2

4

6

8

10

12

2005 2006 2007 2008

Year

No.

of s

peci

esC SC

C R

Y5 SC

Y5 R

Figure 9. The mean number of herb species recorded for the four treatments (C SC – control, short cut; C R – control, rotovation; Y5 SC – R. minor sown in 2005, short cut; Y5 R – R. minor sown in 2005, rotovation) which were not sown with wildflowers (+SE). Data taken from the August survey for each year. N = 5

Figure 9 shows the mean number of different herb species recorded, for the treatments

which were not sown in wildflower mix, to see if R. minor is increasing species

richness by creating a more favourable habitat by reducing grass vigour. The graph

shows that the treatments containing R. minor have a higher number of species

present for each year between 2006 and 2008. The baseline data (2005), before

ground preparation and R. minor application, shows no difference between the control

and R. minor plots. Repeated measures ANOVA does not show a significant result for

ground preparation (F=0.312, NS) or R. minor (F=0.010, NS); however, year was

significant (F=59.524, ***p<0.001).

4. Results – Site two

4.1 R. minor

R. minor was not found in any of the random quadrats over the entire sample period

of April until August 2008 (table 3).

4.2 Wildflowers The full vegetation survey concluded that three out of the five (Achillea millefolium,

Centaurea nigra, and Prunella vulgaris) species of the wildflower mix germinated

22

(table 3). None of the wildflower mix species were found in September 2007 so all

species appear to have come from introducing them; however, random quadrats were

used so this cannot account for the whole area.

Month R.minor A.millefolium C.nigra K.arvensis L.vulgare P.vulgaris September 0 0 0 0 0 0 April 0 14 4 0 0 0 May 0 12 22 0 0 0 June 0 10 28 0 0 0 July 0 1 57 0 0 2 August 0 6 4 0 0 0

Table 3. The total number of each wildflower species germinated in the 10 random quadrats each month.

23

5. Discussion

5.1 Site one

After three years of monitoring for this longitudinal study, results appear to provide a

positive outlook for the future. Biodiversity results show that the trend overall seems

to be heading upwards from 2005 to 2008 (figure 4) for each of the treatments.

However, these results should be treated with caution as the sudden increase from

2005 to 2006 for each of the different treatments (including the two controls) is

unlikely to be caused by ground preparation alone. It is more likely to be because of

differences in identification skills with the various surveyors, as each year of the study

was carried out by a different student. With the rise and fall of biodiversity between

2006 and 2008, this illustrates how these initial results do not provide concrete

evidence for biodiversity change. It should be noted that biodiversity change is a slow

process and can take up to ten years to achieve (Walker et al., 2004) so further

monitoring will be required in the future to supply conclusive results. There appears

to be no significant differences in biodiversity between treatments at this early stage

of the restoration of Primley meadow, but changes are likely to become more apparent

in later years.

As a restoration tool, the theory is that R. minor will establish in the area undergoing

restoration and parasitise the coarse grasses residing there; resulting in a reduction in

grass height The results show R. minor has established well in plots where sown

(figure 5). R. minor has a higher rooted percentage cover for plots where the short cut

was used compared to rotovation so it appears R. minor establishes better with this

ground preparation. There is a significant interaction between year and ground

preparation and the difference of R. minor establishment between short cut and

rotovated plots seems to be increasing over the years (figure 5). Over the three years a

decline in R. minor abundance was observed. Westbury (2004) showed a year-to-year

variation in seed production will take place dependant on environmental conditions,

and given that seed doesn’t stay in the seed bank, next years germination is a direct

result of the previous year’s seed production (Gilbert and Anderson, 1998; Westbury

and Davies, 2005). It has been suggested by Pywell et al. (2004) that R. minor takes

three years to establish so a decline over the initial few years is not unexpected. The

24

overall success of R. minor may be because of the abundance of hosts present, as

grasses are the most common components of communities R. minor is associated with

(such as Primley meadow). Therefore, the probability of locating a suitable host is

high (Gibson and Watkinson, 1989). R. minor successfully reduced sward height each

year (figure 6) as shown by previous studies (Pywell et al., 2004). This indicates that

R. minor is parasitising the grasses and reducing their vigour or stunting their growth.

The difference in grass height between plots containing R. minor and those without it

was significant for both 2006 and 2007. The reduction in R. minor (figure 5) over the

years is likely to account for the non-significance shown by data from 2008. Bardgett

et al. (2006) showed how R. minor density affects biomass, species diversity and forb

composition so it is likely grass height is also affected by density, as a reduced

number of R. minor plants will not parasitise so many hosts.

R. minor is speculated to reduce grass biomass and results from this study coincide

with this hypothesis. The average grass biomass was lower for plots treated with

R. minor (figure 7) which indicates that R. minor successfully parasitises the grass

species reducing their vigour. Rotovation also reduced grass biomass when compared

to plots that were short cut; this was only by 0.6 g, however. The order of dominance

of grasses is almost the same from 2005 to 2008. This may be because R. minor

densities are not large enough for the high density of grasses present. With such

excessive grass densities, small differences in host selectivity could be diluted to such

an extent that they are unseen. R. minor could also have no host preference between

these grass species and be parasitising all species equally. R. minor could potentially

be using a different non-grass host or growing autotrophically; although autotrophic

growth within the field is less common (Gibson and Watkinson, 1989). The order of

dominance of each of the grass species shows A. stolonifera, unlike the other species,

has moved from most dominant to fourth position (table 1). This species was

highlighted by Smith et al. (2000) as showing the greatest reduction from originally

high frequencies (35-40 %). Therefore, A. stolonifera may be a target host for

R. minor at Primley meadow.

It has been suggested that sowing wildflower after R. minor application is beneficial

because of gap creation when R. minor dies allowing seedling colonisation the

subsequent year (Pywell et al., 2004). However, the wildflower mix being sown in the

25

same year as R. minor (2005) proved to be the most successful sowing technique with

the highest total percentage cover recorded for species sown in the wildflower mix

(figure 8). Results also show wildflower sown in 2006 had a significantly lower

percentage cover when compared to both plots without wildflower mix sown and

those when sown in 2005. This suggests that sowing wildflower mix the following

year is not beneficial for wildflower germination. On the other hand, low germination

rates of wildflower when sown in 2006 could be attributed to poor environmental

conditions or a less viable seed mix that year. It must also been taken into account that

seeds sown in 2005 have had longer to establish and are likely to have seeded twice

by 2008, compared to seeds sown in 2006 which will have only seeded once. Nearly

all treatments show an increase in wildflower percentage cover across the years

(figure 8) with particularly large increases in later years, as the wildflowers become

more established and start seeding, for treatments where wildflower mix was sown.

The mean number of species recorded was higher for the treatments with only

R. minor sown: Y5 SC (R. minor application and short cut) and Y5 R (R. minor

application and rotovation) than either of the controls: C SC (control and short cut)

and C R (control and rotovation) (figure 9). This suggests that R. minor is reducing

grass vigour and other dominant species allowing a wider range of species to survive

because the habitat has become more favourable. This shows species richness can

potentially increase with changes in habitat conditions. The results are non-significant

but it is not to be expected that species composition would change dramatically in a

matter of a few years. It also emphasises the need for sowing supplementary

wildflowers because the limited seed bank could potentially delay restoration (Bakker

and Berendse, 1999).

5.2 Site two The results indicate that R. minor appears not to have germinated at site two (table 3).

This may be because of non-viable seeds purchased. Environmental conditions are

unpredictable and as Westbury (2004) states R. minor yield is directly affected by

this. Wet summers are becoming the norm of recent years so as R. minor sets seed

from June onwards this would result in seed quality being reduced. R. minor doesn’t

stay in the seed bank each year (Gilbert and Anderson, 1998; Westbury and Davies,

2005) so more seed will need to be sown the following year. R. minor requires a

26

chilling period to break dormancy over the winter (Smith et al., 2000); Ter Bong

(2005) states Rhinanthus species germination can be effected by both the temperature

and the duration of chilling. The winter of 2007 may have not provided the essential

chilling needed for the lifecycle of R. minor. It is not surprising that the numbers of

wildflower mix that germinated are relatively low (table 3) as this is the first year of

the study and many perennials require at least two years before plants are mature

enough to flower and several growing seasons to properly establish (landlife online).

5.3 Limitations and improvements

One of the problems of a longitudinal study, conducted by different people, is the

inconsistency of identification skills. Identification skills also improved dramatically

over the year with practice. This cannot be quantified but should be taken into

account.

The drop disc technique was a reasonably reliable method to measure grass height.

However, reliability decreased when the grass was longer and folded over in August.

Grass height also varied among the quadrat so the random throwing of the disc onto

the quadrat didn’t always represent the entire area.

The 20 cm2 quadrat used for the biomass sampling was effective at giving a reading

of grass productivity. Even so, only 1 % of the total area was sampled which reduced

accuracy, in particular if large forb species were present within the 20 cm2 quadrat.

Primley Park provides a vital habitat for many invertebrate species, such as the great

green bush cricket Tettigonia viridissima which features in the Devon Biodiversity

Action Plan. To further this project, a logical step to take is to look at the next level in

the food chain i.e. invertebrates. This would provide data on the impact of increasing

species richness on invertebrates. However, this aspect, is clearly long term and not

possible with the size of the small quadrats used for this project at site one.

Additional study into soil temperature and pH could provide answers to why R. minor

did not germinate at site two. Berendse et al. (1992) has also suggested that

restoration of species rich grasslands is affected by various environmental factors

which have not been touched on in this study.

27

5.4 Future management

Restoration of grassland takes many years to achieve so changes in biodiversity are

not expected at these early stages of the project. Primley meadow will continue to be

monitored in the following years to gather data on the long-term changes in

biodiversity. Site one has provided evidence regarding the best treatment (YW5 SC)

so further plots of this treatment will be set up around different parts of the meadow.

Site two will require additional R. minor seed to be sown after the ground is short cut

again in autumn. It is hoped that seed dispersal will occur across the meadow, with

the aid of the continuation of the annual hay cut each autumn, and Primley meadow

will become much more species rich in both flora and fauna in the future.

28

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33

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Word count: 6288

34

7. Acknowledgments Special thanks to Dr Amy Plowman, Dave Ellacott, Tracey Hamston and Andrea

Stacey for all their help, support and advice. Thanks also to the rest of the Field

Conservation and Research team and everyone else at Paignton Zoo for making my

year here such a useful and enjoyable one.

35

8. Appendix Simpson’s Index of Diversity = 1- ((�n (n-1)) / (N (N-1)))