Comparison of moss cover in Different Sections 1999.

Changes in Moss Abundance
1998 - 1999.
Eurhynchium praelongum

Changes in the abundance of the moss Eurhynchium praelongum. 1998 - 1999

Eurhynchium praelongum increased dramatically in extent over the year in all sections, with the exception of section 4. In section 4, the dominant grasses had formed such thick tussocky bases that few mosses were able to colonize the ground layer.

This species is normally abundant in woods and hedgerows, but occurs across a wide range of habitats, including fields and marshes. It is a particularly shade tolerant species. This is an important feature which has allowed this moss to become dominant in the ground layer of the project site, despite being shaded by much taller vegetation for much of the year.

Thuidium tamarascinum

Changes in the abundance of the moss Thuidium tamarascinum 1998 - 1999

The amount of Thuidium tamarascinum increased substantially in all sections except sections 4 and 9. It has already been noted that grass growth restricted the establishment of moss in section 4.

This moss is more often found in woods and on hedgebanks, but it will also grow with other mosses amongst grass in open situations, as on the Heathland Restoration Project site. This moss and Eurhynchium praelongum, were the commonest moss species in section 5, the control strip. This completely unmanaged section is beginning to resemble a young woodland. These two shade tolerant moss species thrived on the trunks and bases of the tall gorse bushes and young saplings in this section.

Polytrichum formosum

Changes in the abundance of the moss Polytrichum formosum 1998 - 1999

Polytrichum formosum is primarily a woodland moss, although it also occurs on well drained heaths. On the Heathland Restoration Project site, this moss usually grows as thick carpets, often up to 10cm in height, in the more open areas. It is much less likely than the other mosses to be found intertwining among the grasses.

Other Polytrichum species such as P. piliferum and P. juniperum are more characteristic of heaths, being especially common as colonists on newly burnt sites. Distinguishing between individual species of Polytrichum in the field can often be difficult. Individual plants of the same species can vary widely in appearance and size depending on environmental conditions. Separating the species often requires microscopic examination and slide preparations to make certain of identification.

Polytrichum piliferum and P. juniperum have not been recorded in the survey quadrats, but it is entirely possible that species of Polytrichum other than P.formosum are present on the project site. Time has simply not been available to individually examine every clump and stand of this widespread moss on the project site.

Hypnum jutlandicum

Changes in the abundance of the moss Hypnum jutlandicum 1998 - 1999

This characteristic heathland moss, formerly classified as a variety of Hypnum cupressiforme (H.cupressiforme var.ericetorum) is now considered sufficiently different to warrant specific status in its own right. It occurs on acid soils, especially on heaths and among Heather (Calluna). This species decreased in several of the grassier sections of the project site, but increased where Calluna was common (below)

Comparison of Hypnum jutlandicum distribution with Heather (Calluna) 1999

Comparison of Hypnum jutlandicum distribution with Calluna.

The comparisons between sections have been made using % frequency (with data taken from all the quadrats sampled, both belt and random) as a measure of abundance.

Percentage frequency = the percentage of the total number of quadrats sampled which contained the species. For example, a percentage frequency of 100%, means that the species was found in all quadrats sampled.

Percentage frequency has been used as a measure of abundance rather than mean % cover, because in many cases, changes in moss mean % cover were relatively small from one year to the next. This disguised the fact that many of the mosses had greatly increased in extent across the site over the year. This is demonstrated by the fact that they were found in a much higher percentage of the quadrats sampled.

The % frequencies shown above are based on an average of 22 quadrats sampled per section. Differences of 10% frequency (which equates to a difference of approximately 2 quadrats) or less should not be regarded as significant.