MAVIS (Modular Analysis of Vegetation Information System) The computer program MAVIS (Smart, 2000) was used in this study as a

further method to aid comparison between the data collected from each site and the National Vegetation Classification communities (e.g. Rodwell, 1992).

The program compares the collected data with the NVC constancy tables and produces a list of possible matches for the collected data. It also calculates a co-efficient of similarity as a measure of how similar the program finds the data to the chosen NVC community¹¹. Its value is between 0 and 100. As previously mentioned, the NVC system used 2 m x 2 m quadrats when collecting the data, therefore, any discussion of results from MAVIS needs to take this into account.

side of the split or the other (Hill and Smilauer, 2005)). Differential species are qualitative; therefore, TWINSPAN instead identifies a quantitative alternative, termed a pseudospecies (Hill and Smilauer, 2005). These are species found at a particular level of abundance (Hill and Smilauer, 2005), e.g. the split could be made on the basis of samples with Centaurea nigra at an abundance of between 26 and 50% abundance (level 3 in the default settings) and samples without Centaurea nigra at this particular level of abundance. These pseudospecies can be strongly associated with one side of the division or the other, in which case they are identified by the program as indicator species for these groups. In other cases, they may only be weakly associated with a group and so are identified as preferential species. These indicator and preferential species help to characterize the different groups. On dendrograms, indicator species are shown as the abbreviated species name with the level of abundance after it. Preferential species are shown in the same way but the name and level are in square brackets.

11 Matching follows the same application of the Czekanowski coefficient as MATCH (Smart, 2000);

MATCH is a program written for pre-Windows systems by Malloch (1990).

50

Chapter 3

Species-rich meadow creation using the introduction of green hay in two consecutive years

3.1 Introduction

Strewing species-rich green hay is an effective grassland creation technique that creates a plant community similar to that of the source site (Trueman and Millett, 2003; Donath et al., 2007; Edwards et al., 2007; Rydgren et al., 2010; Starr-Keddle and Barrett, 2012) (Section 1.2). However, a number of characteristic grassland species fail to establish, or establish but persist poorly in re-created communities (Pywell et al., 2003; Hewins et al., 2012).

Pywell et al. (2003) analysed the results of 25 grassland creation and

restoration experiments. They found that generalist species performed well, whereas other species, particularly those that are specialists of this habitat type, perform poorly. Hewins et al. (2012) in a review of 36 sites where species-rich grassland creation had been carried out under option HK8¹² of the Higher Level Stewardship Scheme¹³ found that, although 17% of the sites could be described as good quality BAP habitat and 47% met lower definitions of BAP grassland, positive indicator species, particularly high value ones, were still lacking. It is crucial to find ways to improve the success of poorly performing species for a number of reasons, including to increase the similarity of created species-rich grasslands to ‘target’

12 HK8 is the option under which species-rich grassland creation is funded.

13 After five years of the scheme.

51 natural communities (Pakeman et al., 2002; Smith et al., 2003) and because these species may be key to food and pollinator webs in grasslands, for example, being food plants of invertebrates that are important for

conservation (Pywell et al., 2003). Therefore, although green hay strewing is successful in creating new species-rich grasslands, there are potential

modifications to this technique.

When creating species-rich grassland on sites that are species-poor, it is essential to create opportunities for establishment in the sward, either

through the creation of gaps or through the complete removal of the existing vegetation (Wells et al., 1981; Bullock et al., 2001; Trueman and Millett, 2003; Hofmann and Isselstein, 2004; Rayner, 2005; Edwards et al., 2007).

The herbicide glyphosate is often recommended as the method to achieve the removal of the existing vegetation (e.g. Wells et al., 1981; Besenyei, 2000; Trueman and Millett, 2003; Flora Locale, 2005; RHS, 2017; University of Bristol, 2017; British Flora, no date; Bumblebee Conservation Trust, no date; Newcastle City Council, no date; SNH, no date), although there is also evidence that glyphosate has detrimental effects, for example, on soil micro-organisms such as arbuscular mycorrhizal fungi (AMF) (Druille et al., 2015) and also on earthworms (Gaupp-Berhausen et al., 2015).

This experiment investigates whether strewing species-rich hay in two consecutive years onto a species-poor grassland that has been glyphosated, introduces more species into the receiver meadow than strewing species-rich hay in just one year onto a glyphosated species-poor grassland. The hay was

52

from the same source meadow on both occasions. Given the length of the time available for completion of this thesis and also that no published article was found with results for multiple strewing, two strews (rather than three or more strews) was chosen for this experiment. The experiment also investigates which species are difficult to transfer, in order to consider why they are more difficult and what their specific requirements might be.

Aim:

To investigate the effect on community transfer and species-richness, of strewing green hay from a species-rich source meadow, twice in consecutive years; i.e. creation of a new meadow.

Objectives:

To treat an existing grassland area of low species diversity with herbicide to remove the existing vegetation.

To create a meadow on the area by strewing green hay.

To add further hay to the created vegetation in the subsequent year from the same source site.

To compare the vegetation in the receiver meadow (before treatment, once-strewed and twice-once-strewed treatment areas), with the source meadow.

53 3.2 Methods

3.2.1 Site Descriptions