Axiophytes in the landscape

(or – everything you wanted to know about axiophytes but were afraid to ask...)

Sarah Whild1 , Alex Lockton2 , Jeremy Ison3 and Richard Aisbitt3

Division of Biology and Conservation Ecology, Manchester Metropolitan University1, Whild Associates/BSBI2,

School of Biosciences (University of Birmingham)3

Axiophytes – what are they?This innovative approach has allowed for the creation of county indicator lists that can be used for conservation planning for sites and wider landscape use.

Axiophytes (‘worthy’ plants or ecological indicators) have been used by the Botanical Society of the British Isles (BSBI) as a way of creating indicator species lists for vice-counties throughout Britain and Ireland

Axiophytes – what are they?An exception to the 25% rule can be made for species in conservation habitats that are particularly well represented and widespread in the county.

An axiophyte list for a county is derived by taking all species that were restricted to BAP habitats (90% of records) and also found in 25% or fewer tetrads in the vice-county.

These axiophytes can then be allocated to one or more broad habitat types.

Axiophytes have been used for:

Assessing wildlife sites

Site selection and monitoring

Prioritising sites for habitat restoration

Identifying landscape units for broad-leaved tree planting

Using axiophytes for site selection and monitoring in Devon and

Wiltshire:

• How effective are axiophytes as a measure of site condition?

• Are significantly more axiophytes recorded for ‘high quality’ sites than those of ‘low quality’ and can this be used to discriminate between two sets of sites?

• Do grid squares containing designated sites have significantly more axiophytes than those that do not?

• Are individual axiophytes more likely to occur in high quality sites than those of low quality

• Can coincidence maps of axiophytes allow for targeted surveying at a landscape scale?

County Wildlife Sites (CWS) in Devon were previously assessed using the Integrated Habitat System (IHS) which does not require any species identification.

CW sites were assessed without any empirical evidence in the form of validated biological records.

Broad habitat types in Devon

Tetrad axiophyte coincidence map for Devon

1 - 1011 - 2021 - 3031 - 4041 - 5051 - 6061 - 7071 - 8081 - 164

A list of 416 axiophytes were identified for Devon

There are 2078 County Wildlife Sites and data were analysed for 29 that were approved as CW Sites and 23 that had been rejected using the IHS scheme together with a panel of local experts.

Figures suggested a threshold of 20 axiophytes would be needed to qualify as a CW Site and this was used to predict which sites would be accepted at the selection panel meeting.

Two sites that would have been accepted by the axiophyte method were rejected and six sites that would have been rejected were accepted out of a total of 41 sites.

A list of 311 axiophytes were identified for Wiltshire

Counts of axiophytes were compared across sites with different levels of protection

SSSIs had an average of 46 axiophytes

WWT reserves had 45 (very close to SSSIs)

Unprotected CWTs had 24

From these figures it was relatively straight forward to suggest a proposed cut-off point for designation for SSSIs and also for CW Sites

A tetrad coincidence map of axiophytes for Wiltshire suggested that axiophyte coincidence mapping could be used to target ‘new’ sites that had not been previously identified for conservation

Hot spots showed tetrads that stood out as having no designated sites but high levels of axiophytes – thus providing targets for survey

Using axiophytes for conservation planning

Axiophytes of the Meres and Mosses

123 species were chosen including 18 bryophytes

The county recorders for Shropshire, Cheshire and Staffordshire drew up a list of wetland axiophytes typical of the meres and mosses

A coincidence map of these species was then produced in order to highlight hotspots for restoration and conservation

The most important plant species for the Meres and Mosses are wetland species

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Sites were then ranked according to total axiophyte species richness

across time

Rank Total Current Decline Key sites1 76 11 86% The Mere, Ellesmere2 74 10 86% Bomere Pool3 72 42 42% Cole Mere4 70 46 34% Wybunbury Moss5 68 36 47% Whixall Moss6 67 38 43% Bomere, Shomere & Betton Pools7 64 35 45% Hatch Mere & Flaxmere8 62 48 23% Brown Moss9 61 32 48% Sweat Mere & Crose Mere10 55 11 80% White Mere11 55 39 29% Aqualate Mere12 54 26 52% Wem Moss13 53 12 77% Oak Mere14 50 19 62% Rostherne Mere15 49 31 37% Berrington Pool16 48 28 42% Clarepool Moss & Newton Mere17 47 31 34% Danes Moss18 45 7 84% Hencott Pool19 44 16 64% Fenemere20 44 31 30% Balterley Heath

DC0 <1929DC1 1930-1969DC2 1970-1986DC3 1987-1999DC4 2000-2009DC5 2010 plus

Date class 1 DC1 (1930-1969) is noticeably under-recorded in all the sites but the other date classes have comparable recording effort.

Taking the four sites with the largest total decline in number of species, we can give a more detailed breakdown by date class, showing variations in recording effort.

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The Mere, Ellesmere Hencott Pool

Bomere Pool White Mere

But White Mere is noticeably different, with no change in the number of axiophytes between DC0 and DC2, and no change between DC3 and DC4.

Three of the sites have broadly similar profiles, with the number of axiophytes decreasing by a factor of 2 between DC0 and DC2, and again halving in number by DC4.

This suggests that White Mere retained its axiophytes until relatively recently, and it has not deteriorated noticeably in the recent past. This could be justification for prioritising resources on White Mere, as recent changes are more likely to be reversible.

Taking the four sites with the largest total decline in number of species, we can give a more detailed breakdown by date class, showing variations in recording effort.

Sweat Mere – a site that has remained in favourable condition

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What to do about White Mere?

How do the axiophytes break down into habitats?

Ancient Recent Present total

Bog 2 2

Carr 1 1 3 5

Grassland 4 1 5

Marginal 7 6 9 22

Open water 1 2 3

Woodland 1 2 12 15

Total 16 11 26 53

Bog species have disappeared completely (Andromeda polifolia)

Carr is in reasonable condition

Grassland disappeared long ago with a mixture of species including calcicoles

Clinopodium acinos and marshier species such as Triglochin palustris

Marginal species have been hit hard with Schoenoplectus

tabernaemontani, Oenanthe aquatica and Phragmites australis

Dry woodland is in favourable condition

Most of these species are light loving species of

open, wetter conditions so shade

has increased.

Remove trees from the water’s edge in appropriate places

and restore marginal grazing

Target speciesBaldellia ranunculoidesBidens cernuaCarex rostrataCicuta virosaElatine hexandraLittorella unifloraLuronium natansOenanthe aquaticaOenanthe fistulosaPhragmites australisRanunculus linguaRumex hydrolapathumSchoenoplectus lacustrisSchoenoplectus tabernaemontaniTriglochin palustris

Conservation resources should be focused on the sites with the greatest number of these axiophytes, and the greatest urgency is for sites where there is a demonstrable decline

This can only be detected retrospectively, so ‘evidence of a recent loss of axiophytes’ is the appropriate trigger for intervention.

White Mere is the site with the highest and most recent decline

Axiophyte data tables can be used for monitoring further changes in the conservation status of the meres and mosses.

The more frequently that the sites are thoroughly surveyed, the more powerful this technique becomes.

To maximise the potential of this sort of analysis, all SSSIs should be surveyed thoroughly at least once a decade.

Axiophytes and Opportunities – a case study in working with local partners with biological recording data

In 2006 the Forestry Commission asked Shropshire County Council (now Shropshire Council) if they could provide a Woodland Opportunity map which highlighted areas that were more, or less, sensitive to new woodland planting.

The use of axiophytes to produce such a map would provide an evidence-based approach to mapping.

Axiophytes and Opportunities – a case study in working with local partners with biological recording data

MethodsAn axiophyte list for Shropshire was derived by taking all species that were restricted to BAP habitats (90% of records) and also found in 25% or fewer tetrads in the vice-county. These axiophytes were then allocated to one or more broad habitat types.

The woodland and grassland axiophytes were then coincidence-mapped to identify the areas of greatest value for woodland and grassland. The coincidence data were transferred to GIS and mapped onto Landscape Description Units so axiophyte species densities could be allocated to each landscape ‘patch’.

Axiophytes and Opportunities – a case study in working with local partners with biological recording data

Axiophytes and Opportunities – a case study in working with

local partners with biological recording

data

Axiophytes and Opportunities – a case study in working with local partners with biological recording data

ResultsThe resulting map then showed where woodland planting schemes could take place without compromising species-rich grassland and where woodland planting schemes could work effectively to link existing blocks of ancient woodland.

Conclusions and applicationsThis demonstrates how existing empirical, repeatable, presence-absence data is used to produce habitat maps which would otherwise have been expensive to collect and subject to a high degree of subjectivity. The resulting map is quantifiable and evidence-based.

Woodland planting schemes in Shropshire can now be targeted more effectively. This system has been adopted by the West Midlands Biodiversity Group.

What can we learn from case studies on axiophyte use?

Axiophytes can provide useful insights into how to assess sites empirically, using an evidence-based approach

Axiophytes indicate favourable conditions – the more axiophytes the better quality the habitat

Axiophytes can include bryophytes, not just vascular plants

They can be used to answer specific questions on site conservation, conservation prioritization and landscape scale issues

They should be used with a small degree of caution, bearing in mind issues of scope of recording especially when using time-sliced data

References

Aisbitt, R. 2012. Can axiophyte counts be used to assess wildife sites? University of Birmingham MSc Thesis

Belton, L. 2011. An algorithm to enumerate axiophyte richness in SSSIs. BSBI Recorder 15.

Ison J. 2011. Axiophyte diversity versus total species diversity in Devon. BSBI Recorder 15.

Lockton, A., Wrench, D., Whild, S. Diack, I. & McCullagh, F. 2007. Identifying conservation priorities in the Meres & Mosses Natural Area by using axiophytes. Unpublished report to Natural England.