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Charismatic Churchyard Lichens

Posted: Friday 2nd February 2018 by MonitoringandResearch

Lichens in churchyardsLichens in churchyards

Ryan Clarke explains how the new Northamptonshire Lichen Group was formed and some of the best places to find lichens

Look closely at churches and structures in their churchyards and a hidden world will be revealed before your very eyes. Lichens are fascinating organisms, they are often overlooked but are essential to a whole variety of other species and beautiful in their own right. They also make excellent environmental indicators! Northamptonshire Biodiversity Record Centre’s WILDside Project is all about encouraging recording of wildlife in Northamptonshire, even more obscure groups like lichens.

After an introductory lichen talk at the Northamptonshire Natural History Society from Mark Powell (lichen county recorder for Northamptonshire), the Northamptonshire Lichen Group was formed - a partnership between Mark, NBRC and the Northamptonshire Natural History Society. Churchyards make a great place to start to study lichens and we had a great event at Billing Road Cemetery looking at the lichens that grow there. There will be more events like this in the future - contact us to find out more.

What makes churchyards so good for lichens and how can we conserve them? Mark Powell explains: "Lichens in churchyards, churches and their memorials are often the oldest man-made stone structures in the local landscape. Many churchyards have changed little over decades or centuries and this has provided the ecological continuity that slow-growing species need to become established. This antiquity, along with the diversity of stone types, often results in a remarkable diversity of lichen species.

"In lowland Britain, where there are few natural stone outcrops, churchyards are usually the most important sites for lichens that grow on stone. Generally, the oldest stones (church walls and old memorials) support the most notable lichens. Old weathered wooden structures, particularly those that are untreated with preservatives, are an increasingly rare habitat in the landscape. Old gate posts, lych gates, wooden grave markers and bench seats are sometimes of great importance. Lichens also grow on mosses, pebbles, chippings, trees and on the ground (especially within curbed graves). Some churchyard lichens are rare, and a few are restricted to churchyards. Lichens are links in an ecological chain. Many invertebrates, including moths, depend on lichens for food and shelter. 

"Church buildings are also of importance for the interesting communities associated with metal-contaminated stonework. Copper compounds leaching from roofs and lightning conductors often stain stonework blue and stimulate specialist lichen communities. Old iron window grilles turn limestone windowsills rusty brown and create a different community. Such windowsills are often dominated by Verrucaria obfuscans, a species added to the British list as recently as 2015. There are still many lichens we encounter in lowland churchyards which aren’t properly understood, some of which are almost certainly undescribed species."

Management of churchyards for lichen conservation

The survival of lichen diversity is dependent on how the churchyards are looked after. The main threats are as follows:

• Ivy can rapidly destroy ancient and important lichen communities. Although ivy provides useful habitat, it is common and widespread. Many lichens are restricted to old stonework and memorials. The lichens should take priority on these.

• The shade from expanding tree crowns can kill lichen communities which have taken decades or centuries to develop in well-lit conditions. Most churchyards are, historically, patches of open space. The negative effects of tree planting proposals should be seriously considered.

• Rank vegetation results in heavy browsing by molluscs resulting in a deterioration of lichen communities. The grassland of churchyards requires regular management for lichens on memorials to thrive. Allowing some areas to grow like a hay meadow, for flowering plants and insects, is acceptable. Non-intervention should only be considered in limited areas where there are few or no memorials.

• Insensitive restoration and cleaning of stonework and memorials may cause unnecessary damage. Repair work (such as repointing) should be restricted to areas where such work is essential, leaving other patches untouched to provide ecological continuity. Old dressed stonework (windowsills, buttress slopes and chamfered plinths) should only be replaced when essential. Those that remain should not be aggressively cleaned.

• Removal or repositioning of memorials should be avoided.

The British Lichen Society can provide further information and advice. For example, a free survey could be carried out to see if the lichen communities are of conservation value. A lichenologist could come and meet with parishioners to talk about lichens and explain about their conservation. Advice can be given about how to make repairs in a way that lichens are protected, while disruption of the work is minimised.  

The nationally rare Rinodina Calcarea

Old wooden gate posts and lych gates are an important habitat


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